Displaying publications 121 - 140 of 308 in total

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  1. Studies on the resistance of malaria to chloroquine and to a combination of chloroquine and pyrimethamine in Peninsular Malaysia
    Dondero TJ, Parsons RE, Ponnampalam JT
    Trans R Soc Trop Med Hyg, 1976;70(2):145-8.
    PMID: 785725
    In vivo chloroquine resistance surveys, which allowed for detection of late recrudescing RI resistance, were conducted in three regions of Peninsular Malaysia, which were previously not recognized as having appreciable drug resistance. Among the 485 Plasmodium falciparum infections tested resistance rates ranged locally from 20% to 67% in those with parasitaemias over 1,000 per mm3, and 5% to 59% in all parasitaemias. The region found to have the most serious resistance was western Pahang. In one study a combination of chloroquine and pyrimethamine proved no more efficacious than chloroquine alone. Most of the resistance encountered was the late recrudescing RI type. There was no apparent correlation between drug resistance and Anopheles balabacensis as this species was not found despite intensive collections in two of the three main regions. There was no evidence of resistance among the 222 P. vivax and 35 P. malariae infections also tested.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  2. Simian malarias in man: facts, implications, and predictions
    Coatney GR
    Am J Trop Med Hyg, 1968 Mar;17(2):147-55.
    PMID: 4869108
    Matched MeSH terms: Plasmodium falciparum/pathogenicity
  3. Susceptibility studies of Plasmodium falciparum isolates and clones against cycloguanil and pyrimethamine using the modified in vitro microtechnique
    Ang HH, Chan KL, Mak JW
    J Parasitol, 1996 Dec;82(6):1029-31.
    PMID: 8973418
    Six clones were derived from each Malaysian Plasmodium falciparum isolate and characterized for their susceptibilities against type II antifolate drugs, cycloguanil and pyrimethamine. Results showed that these isolates were of a heterogeneous population, with average IC50 values of Gombak C clones at 0.012-0.084 microM and 0.027-0.066 microM, ST 9 clones at 0.019-0.258 microM and 0.027-0.241 microM, ST 12 clones at 0.015-0.342 microM and 0.012-0.107 microM, ST 85 clones at 0.022-0.087 microM and 0.024-0.426 microM, and ST 148 clones at 0.027-0312 microM and 0.029-0.690 microM against cycloguanil and pyrimethamine, respectively. Generally, most of these clones displayed susceptibility patterns similar to their parent isolates except ST 9/A4, ST 9/A7, ST 9/B5, ST 9/D9, ST 9/D10, ST 148/A4, ST 148/A5, ST 148/A7, ST 148/F7, ST 148/F8 clones, which were sensitive at 0.027 microM, 0.019 microM, 0.022 microM, 0.063 microM, 0.037 microM, 0.031 microM, 0.042, microM, 0.042 microM, 0.062 microM, and 0.027 microM, whereas, ST 12/D7 clone was resistant at 0.342 microM, against cycloguanil respectively. However, ST 9/A4, ST 9/D8, ST 12/D5, ST 85/A5, ST 85/B3, ST 85/B4, ST 85/D3, ST 85/D7, ST 148/A6, and ST 148/A7 clones were resistant to pyrimethamine at 0.158 microM, 0.241 microM, 0.107 microM, 0.223 microM, 0.393 microM, 0.402 microM, 0.426 microM, 0.115 microM, 0.690 microM, and 0.520 microM, respectively.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  4. Efficacy and resistance of different artemisinin-based combination therapies: a systematic review and network meta-analysis
    Mathenge PG, Low SK, Vuong NL, Mohamed MYF, Faraj HA, Alieldin GI, et al.
    Parasitol Int, 2020 Feb;74:101919.
    PMID: 31015034 DOI: 10.1016/j.parint.2019.04.016
    BACKGROUND: Malaria parasites have developed resistance to most of the known antimalarial drugs in clinical practice, with reports of artemisinin resistance emerging in South East Asia (SEA). We sort to find the status of artemisinin resistance and efficacy of different modalities of the current artemisinin-based combination therapies (ACTs).

    METHODS: We carried out a systematic search in 11 electronic databases to identify in vivo studies published between 2001 and 2017 that reported artemisinin resistance. This was then followed by A network meta-analysis to compare the efficacy of different ACTs. Quality assessment was performed using the Cochrane Risk of Bias (ROB) tool for randomized controlled trials and National Institute of Health (NIH) tool for cross-sectional studies. The study protocol was registered in PROSPERO under number CRD42018087574.

    RESULTS: With 8400 studies initially identified, 82 were eligible for qualitative and quantitative analysis. Artemisinin resistance was only reported in South East Asia. K13 mutation C580Y was the most abundant mutation associated with resistance having an abundance of 63.1% among all K13 mutations reported. Although the overall network meta-analysis had shown good performance of dihydroartemisinin piperaquine in the early years, a subgroup analysis of the recent years revealed a poor performance of the drug in relation to recrudescence, clinical failure and parasitological failure especially in the artemisinin resistant regions.

    CONCLUSION: With report of high resistance and treatment failure against the leading artemisinin combination therapy in South East Asia, it is imperative that a new drug or a formulation is developed before further spread of resistance.

    Matched MeSH terms: Plasmodium falciparum/drug effects*
  5. A new antiplasmodial sterol from Indonesian marine sponge, Xestospongia sp
    Murtihapsari M, Salam S, Kurnia D, Darwati D, Kadarusman K, Abdullah FF, et al.
    Nat Prod Res, 2021 Mar;35(6):937-944.
    PMID: 31210054 DOI: 10.1080/14786419.2019.1611815
    A new antimalarial sterol, kaimanol (1), along with a known sterol, saringosterol (2) was isolated from the Indonesian Marine sponge, Xestospongia sp. The chemical structure of the new compound was determined on the basis of spectroscopic evidences and by comparison to those related compounds previously reported. Isolated compounds, 1 and 2 were evaluated for their antiplasmodial effect against Plasmodium falciparum 3D7 strains. Compounds 1 and 2 exhibited antiplasmodial activity with IC50 values of 359 and 0.250 nM, respectively.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  6. Quantitative assessment of antimalarial activities from Malaysian Plasmodium falciparum isolates by modified in vitro microtechnique
    Hoon AH, Lam CK, Wah MJ
    Antimicrob Agents Chemother, 1995 Mar;39(3):626-8.
    PMID: 7793863
    Malaysian, TGR (Thailand), and Gambian (West African) Plasmodium falciparum isolates were cultured in vitro by the candle jar method and were characterized for their susceptibilities to present antimalarial drugs by the modified in vitro microtechnique. Results showed that 93 and 47% of the Malaysian isolates were resistant at 50% inhibitory concentrations of 0.1415 to 0.7737 and 0.1025 to 0.1975 microM, respectively, while the rest were susceptible to choloroquine and cycloguanil at 0.0376 and 0.0306 to 0.0954 microM, respectively. All isolates were susceptible to mefloquine, quinine, and pyrimethamine at 0.0026 to 0.0172, 0.0062 to 0.0854, and 0.0149 to 0.0663 microM, respectively. In contrast, the Gambian isolate was susceptible to multiple drugs at 0.0024 to 0.0282 microM; TGR was resistant to chloroquine at 0.8147 microM but was susceptible to mefloquine, quinine, cycloguanil, and pyrimethamine at 0.0024, 0.0096, 0.0143, and 0.0495 microM, respectively.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  7. Fulltext Measuring pH of the Plasmodium falciparum digestive vacuole by flow cytometry
    Abu Bakar N
    Trop Biomed, 2015 Sep;32(3):485-93.
    PMID: 26695209 MyJurnal
    Studies show that the pH of the malaria parasite's digestive vacuole (DV) plays a key role in the physiological functions of this organelle and antimalarial drug accumulation, and yet is technically difficult to measure. In this study, a flow cytometry-based technique was developed to measure the DV pH using a ratiometric pH indicator, FITC-dextran loaded into the DV of saponin-permeabilized parasites. To calculate the DV pH, a standard pH calibration curve was generated by incubating the saponin-permeabilized cells in buffers with different pH in the presence of an ionophore, CCCP. The measured average pH of the DV was 5.27 ± 0.03 that is approximately the same in the parasites observed microscopically by Hayward et al. (2006) (5.50 ± 0.14) using the same probe. The removal of glucose from the medium, causing a rapid depletion of parasite ATP, resulted in an alkalization of the DV. The DV was reacidified upon restoration of glucose to the medium. This technique provides a rapid, simple and quantitative measurement of the DV pH on a large number of cells. It will also be useful in future attempts to evaluate the effect of antimalarial drugs (i.e. chloroquine and artemisinin-based drugs) in pH changes of the DV.
    Matched MeSH terms: Plasmodium falciparum/chemistry*
  8. Fulltext Antiplasmodial properties of some Malaysian medicinal plants
    Noor Rain A, Khozirah S, Mohd Ridzuan MA, Ong BK, Rohaya C, Rosilawati M, et al.
    Trop Biomed, 2007 Jun;24(1):29-35.
    PMID: 17568375 MyJurnal
    Seven Malaysian medicinal plants were screened for their antiplasmodial activities in vitro. These plants were selected based on their traditional claims for treatment or to relieve fever. The plant extracts were obtained from Forest Research Institute Malaysia (FRIM). The antiplasmodial activities were carried out using the pLDH assay to Plasmodium falciparum D10 strain (sensitive strain) while the cytotoxic activities were carried out towards Madin- Darby bovine kidney (MDBK) cells using MTT assay. The concentration of extracts used for both screening assays were from the highest concentration 64 microg/ml, two fold dilution to the lowest concentration 0.03 microg/ml. Goniothalamus macrophyllus (stem extract) showed more than 60% growth inhibition while Goniothalamus scortechinii root and stem extract showed a 90% and more than 80% growth inhibition at the last concentration tested, 0.03 microg/ml. The G. scortechini (leaves extract) showed an IC50 (50% growth inhibition) at 8.53 microg/ml, Ardisia crispa (leaves extract) demonstrated an IC50 at 5.90 +/- 0.14 microg/ml while Croton argyratus (leaves extract) showed a percentage inhibition of more than 60% at the tested concentration. Blumea balsamifera root and stem showed an IC50 at 26.25 +/- 2.47 microg/ml and 7.75 +/- 0.35 microg/ ml respectively. Agathis borneensis (leaves extract) demonstrated a 50% growth inhibition at 11.00 +/- 1.41 microg/ml. The study gives preliminary scientific evidence of these plant extracts in line with their traditional claims.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  9. Efficacy and safety of dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum malaria in endemic countries: meta-analysis of randomised controlled studies
    Naing C, Mak JW, Aung K, Wong JY
    Trans R Soc Trop Med Hyg, 2013 Feb;107(2):65-73.
    PMID: 23222952 DOI: 10.1093/trstmh/trs019
    The present review aimed to synthesise available evidence on the efficacy of dihydroartemisinin-piperaquine (DP) in treating uncomplicated Plasmodium falciparum malaria in people living in malaria-endemic countries by performing a meta-analysis of relevant studies. We searched relevant studies in electronic data bases up to December 2011. Published results from randomised controlled trials (RCTs) comparing efficacy of DP with other artemisinin-based combination therapies (ACTs), or non-ACTs, or placebo were selected. The primary endpoint was 28-day and 42-day treatment failure. We identified 26 RCTs. Many of the studies included in the present review were of high quality. Overall, DP, artesunate-mefloquine (MAS3) and artemether-lumefentrine (AL) were equally effective for reducing the risk of recurrent parasitaemia. The PCR confirmed efficacy of DP (99.5%) and MAS3 (97.7%) at day 28 exceeded 90%; both are efficacious. Comparable efficacy was also found for DP (95.6%) and AL (94.3%). The present review has documented that DP is comparable to other currently used ACTs such as MAS3 and AL in treating uncomplicated falciparum malaria. The better safety profile of DP and once-daily dosage improves adherence and its fixed co-formulation ensures that both drugs are taken together. Our conclusion is that DP has the potential to become a first-line antimalarial drug.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  10. Seroepidemiology of malaria in Peninsular Malaysia: Plasmodium falciparum antibody profile of adults in four states
    Thomas V, Bin HK, Leng YP
    Trans R Soc Trop Med Hyg, 1980;74(3):375-80.
    PMID: 7001690
    In 1973, 2610 sera were collected from adults living in 22 localities in four states in Peninsular Malaysia and tested by IFAT for Plasmodium falciparum antibodies. A larger number of thin films were examined. The attack phase of the Malaria Eradication Programme (MEP) in these areas was started between 1968 and 1973. The results showed that the highest prevalence rates and geometrical mean reciprocal titres (CMRT) were among adults from Kelantan where the antibody prevalence varied greatly among the adults and there was active transmission in at least three areas. The values were lowest for Kedah. The P. falciparum antibody prevalence rates were higher than the parasite rates as revealed in single thin film examinations but a number of the positive sera were reactive only at low titres. The low concentration probably indicated the residual antibody from cured cases or past infections and cross reactions to P. vivax and P. malariae infections. The strong reactions probably indicated current P. falciparum transmission as shown by positive thin films. The present study showed that the antibody profile of adults, as shown by IFAT, is of considerable value in assessing the malaria situation in a given area and that it would be useful as a malariometric tool in epidemiological studies to evaluate the progress of malaria eradication/control programmes.
    Matched MeSH terms: Plasmodium falciparum/immunology
  11. Letter: Falciparum malaria resistant to chloroquine suppression but sensitive to chloroquine treatment in West Malaysia
    Lewis AN, Dondero TJ, Ponnampalam JT
    Trans R Soc Trop Med Hyg, 1973;67(2):310-2.
    PMID: 4593652
    Matched MeSH terms: Plasmodium falciparum*
  12. Hospital and field traials of sulformethoxine with pyrimethamine against Malaysian strains of Plasmodium falciparum and P. vivax
    Laing AB
    Med J Malaya, 1968 Sep;23(1):5-19.
    PMID: 4237560
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  13. DRUG-RESISTANT FALCIPARUM MALARIA FROM CAMBODIA AND MALAYA
    CONTACOS PG, LUNN JS, COATNEY GR
    Trans R Soc Trop Med Hyg, 1963 Nov;57:417-24.
    PMID: 14081296
    Matched MeSH terms: Plasmodium falciparum*
  14. Increased frequency of chloroquine resistant P. falciparum on a rubber estate in Peninsular Malaysia during two years of systematic chloroquine treatment
    Dondero TJ, Parsons RE, O'Holohan DR
    Southeast Asian J. Trop. Med. Public Health, 1975 Dec;6(4):488-94.
    PMID: 775652
    Chloroquine pressure was applied over a 22 month period on a somewhat isolated, malarious rubber estate by examination of residents at 4-week intervals and treatment of parasitaemias with chloroquine. During this time the monthly attack rate for P. falciparum rose four-fold to an average of nearly 18% per month, while that of P. vivax remained relatively constant at about 8%. Eight in vivo chloroquine resistance studies, which allowed both detection of late recrudescing R-I resistance and estimation of the risk of reinfection, showed an apparent rise in the drug resistance rate, from 12% to 20% prior to the study to the range of 40-50%. Virtually all resistance encountered was R-I in nature. There was no convincing evidence of chloroquine resistance among 148 tested P. vivax infections.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  15. The indirect fluorescent antibody test for malaria
    Collins WE, Skinner JC
    Am J Trop Med Hyg, 1972 Sep;21(5):690-5.
    PMID: 4627546
    Matched MeSH terms: Plasmodium falciparum/immunology
  16. DRUG-RESISTANCE IN FALCIPARUM MALARIA IN SOUTH-EAST ASIA
    SANDOSHAM AA, EYLES DE, MONTGOMERY R
    Med J Malaysia, 1964 Mar;18:172-83.
    PMID: 14157183
    Matched MeSH terms: Plasmodium falciparum*
  17. STUDIES ON THE DISTRIBUTION AND TRANSMISSION OF MALARIA AND FILARIASIS AMONG ABORIGINES IN MALAYA
    WHARTON RH, LAING AB, CHEONG WH
    Ann Trop Med Parasitol, 1963 Jun;57:235-54.
    PMID: 14042655
    Matched MeSH terms: Plasmodium falciparum*
  18. The effects of diaphenylsulfone (DDS) against chloroquine-resistant Plasmodium falciparum
    Degowin RL, Eppes RB, Carson PE, Powell RD
    Bull World Health Organ, 1966;34(5):671-81.
    PMID: 5328901
    In view of the problems caused by the chloroquine-resistance of some strains of Plasmodium falciparum, the authors have investigated the effectiveness of diaphenylsulfone against two such resistant strains, from Malaya and Viet-Nam. They found that diaphenylsulfone given during acute attacks of malaria had a blood schizontocidal activity against the Malayan resistant strain but was not rapidly effective in terminating acute attacks in non-immune persons, and that, when the drug was given prophylactically in relatively small doses, it was substantially effective in preventing patency of mosquito-induced infection with the same strain. The protective effect of diaphenylsulfone is that of a clinical prophylactic or suppressive drug; it does not appear to be a true causal prophylactic. It was also found that the protective effect is vitiated by the concurrent administration of paraaminobenzoic acid.These studies indicate a need for further assessment of the antimalarial value of sulfones and sulfonamides, both alone and in combination with other drugs, for prevention and cure.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  19. Leucophyllinines A and B, bisindole alkaloids from Leuconotis eugeniifolia
    Tang Y, Nugroho AE, Hirasawa Y, Tougan T, Horii T, Hadi AHA, et al.
    J Nat Med, 2019 Jun;73(3):533-540.
    PMID: 30911994 DOI: 10.1007/s11418-019-01297-5
    Two new bisindole alkaloids, leucophyllinines A (1) and B (2) consisting of eburnane and quebrachamine-type skeletons were isolated from the bark of Leuconotis eugeniifolia, and their structures were elucidated on the basis of spectroscopic data. Leucophyllinines A and B showed antiplasmodial activities against Plasmodium falciparum 3D7.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  20. Sub-lethal concentrations of artemisinin alter pH of the digestive vacuole of the malaria parasite, Plasmodium falciparum
    Ibrahim N, Roslee A, Azlan M, Abu-Bakar N
    Trop Biomed, 2020 Mar 01;37(1):1-14.
    PMID: 33612713
    An appropriate pH maintenance within a membrane-enclosed organelle is vital for the occurrence of biological processes. Artemisinin (ART), a potent antimalarial drug has been reported to target the digestive vacuole (DV) of Plasmodium falciparum, which might alter the pH of the organelle, thereby impairing the hemoglobin degradation and subsequent heme detoxification. Hence, a flow cytometry-based technique using fluorescein isothiocyanate-dextran (FITC-dextran) as a ratiometric pH probe was employed to measure the pH of the DV of the malaria parasite treated with ART. Based on the pH calibration curve generated, the steady-state pH of the acidic DV of the non-treated parasites was 5.42 ± 0.11, indicating that FITC-dextran is suitable for detection of physiological pH of the organelle. The alteration of the DV pH occurred when the parasites were treated with ART even at the sub-lethal concentrations (15 and 30 nM) used. The similar effect was shown by the parasites treated with a standard proton pump inhibitor, concanamycin A. This suggests that ART might have altered the DV pH at lower levels than the level needed to kill the parasite. This study has important implications in designing new ART treatment strategies and in generating new endoperoxide-based antimalarial drugs pertaining to the interruption of the pH regulation of the malaria parasite's DV.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
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