LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 85

Search options

  1. Article ; Online: Evaluation of a multiphasic parasite clearance profile after treatment of experimental human infection with the investigational anti-malarial M5717 using segmented mixed effect models.

    Yin, Xiaoyan / Li, Ying / Bagchus, Wilhelmina / Yalkinoglu, Özkan / Bezuidenhout, Deon / Tappert, Aliona / McCarthy, James / Marquart, Louise / Oeuvray, Claude

    Malaria journal

    2023  Volume 22, Issue 1, Page(s) 199

    Abstract: Background: Evaluation of parasite clearance patterns in experimental human infection trials helps increase understanding of drug action. In a previously reported phase Ib trial of a new investigational anti-malarial drug M5717, parasite clearance ... ...

    Abstract Background: Evaluation of parasite clearance patterns in experimental human infection trials helps increase understanding of drug action. In a previously reported phase Ib trial of a new investigational anti-malarial drug M5717, parasite clearance showed a biphasic linear pattern: slow removal phase with a near flat clearance rate followed by a fast clearance phase with a steep slope. In this study three statistical approaches were implemented and compared to estimate the parasite clearance rate for each phase and the time point corresponding to the change of clearance rates (changepoint between the two phases).
    Methods: Data using three M5717 doses 150 mg (n = 6), 400 mg (n = 8), 800 mg (n = 8) were used to estimate biphasic clearance rates. Three models were investigated: firstly, segmented mixed models with estimated changepoint-models with/without random effects in various parameters were compared. Secondly, a segmented mixed model using grid search-this method is similar to the first except that changepoints were not estimated, instead they were selected based on model fit from given candidate values. Thirdly, a two-stage approach whereby a segmented regression model fit to each participant followed by a meta-analysis method. Hourly rate of parasite clearance (HRPC) interpreted as the percentage of parasites removed each hour was calculated.
    Results: The three models generated similar results. Using segmented mixed models, the estimated changepoints after treatment in hours (95% CI) were: 150 mg: 33.9 (28.7, 39.1); 400 mg: 57.4 (52.5, 62.4); and 800 mg: 52.8 (47.4, 58.1). For all three treatment groups, there was nearly no clearance before the changepoints, but rapid clearance in the second phase (HRPC [95% CI]): 150 mg: 16.8% (14.3, 19.1%); 400 mg: 18.6% (16.0, 21.1%); and 800 mg: 11.7% (9.3, 14.1%).
    Conclusions: All three statistical approaches are effective tools to characterize the bi-phasic clearance of M5717 in the phase 1b experimental Plasmodium falciparum malaria human infection study. The statistical approaches produced similar results to estimate the two-phase clearance rates and the changepoint for each treatment dose of M5717. However, the segmented mixed model with random changepoints has several advantages: it is computationally efficient, provides precision for changepoint estimates and is robust concerning outlying datapoints or individuals.
    MeSH term(s) Humans ; Animals ; Parasites ; Antimalarials/therapeutic use ; Malaria, Falciparum/drug therapy ; Kinetics
    Chemical Substances Antimalarials
    Language English
    Publishing date 2023-06-28
    Publishing country England
    Document type Meta-Analysis ; Journal Article
    ZDB-ID 2091229-8
    ISSN 1475-2875 ; 1475-2875
    ISSN (online) 1475-2875
    ISSN 1475-2875
    DOI 10.1186/s12936-023-04627-x
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: Perforated intravenous catheter design is acceptable for the administration of contrast-enhanced computed tomography administration in cancer patients: Results of a pilot randomised controlled trial.

    Gavin, Nicole C / Wignall, Elizabeth / Marsh, Nicole / Marquart, Louise / Dobeli, Karen L / O'Brien, Catherine / Verderosa, Anthony D / Totsika, Makrina / Keogh, Samantha

    The journal of vascular access

    2023  , Page(s) 11297298231171422

    Abstract: Background: Optimising first time success of peripheral intravenous catheter (PIVC) insertion and reducing intravenous (IV) complications in cancer patients undergoing contrast-enhanced computed tomography (CT) is vital to ensure vascular access ... ...

    Abstract Background: Optimising first time success of peripheral intravenous catheter (PIVC) insertion and reducing intravenous (IV) complications in cancer patients undergoing contrast-enhanced computed tomography (CT) is vital to ensure vascular access preservation and diagnostic accuracy. The aim of this study was to test the feasibility of a randomised controlled trial (RCT) evaluating a novel perforated PIVC compared to a standard PIVC.
    Methods: A single centre, parallel-group, pilot RCT was conducted between March and May 2020. Adult participants diagnosed with cancer were randomised to a non-perforated PIVC (standard care) or a PIVC with a novel perforated design (intervention) for the administration of IV contrast. There were two primary outcomes: (1) feasibility of an adequately powered RCT with pre-established criteria; and (2) all-cause PIVC failure. Secondary outcomes included: first insertion success, modes of PIVC failure, dwell time, contrast injection parameters (volume and injection rate), contrast enhancement, radiographer satisfaction and adverse events.
    Results: Feasibility outcomes were met, except for eligibility (⩾90%) and recruitment (⩾90%). In total, 166 participants were screened, 128 (77%) were eligible and of these 101/128 (79%) were randomised; 50 to standard care and 51 to intervention. First time insertion rate was 94% (47/50) in standard care and 90% (46/50) in intervention. The median dwell time was 37 minutes (interquartile range (IQR): 25-55) in standard care and 35 minutes (IQR: 25-60) in the intervention group. There was one PIVC failure, a contrast media extravasation, in the intervention group (1/51; 2%). The desired contrast injection rate was not achieved in 4/101 (4%) of participants; two from each group. Radiographers were satisfied with the contrast flow rate.
    Conclusions: This pilot RCT suggests perforated PIVCs provide expected flow rate, with no evidence of differences in contrast enhancement to non-perforated PIVCs. The feasibility of conducting a larger powered RCT was demonstrated.
    Language English
    Publishing date 2023-06-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2252820-9
    ISSN 1724-6032 ; 1129-7298
    ISSN (online) 1724-6032
    ISSN 1129-7298
    DOI 10.1177/11297298231171422
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  3. Article ; Online: Haematological response in experimental human Plasmodium falciparum and Plasmodium vivax malaria.

    Woolley, Stephen D / Marquart, Louise / Woodford, John / Chalon, Stephan / Moehrle, Joerg J / McCarthy, James S / Barber, Bridget E

    Malaria journal

    2021  Volume 20, Issue 1, Page(s) 470

    Abstract: Background: Malaria-associated anaemia, arising from symptomatic, asymptomatic and submicroscopic infections, is a significant cause of morbidity worldwide. Induced blood stage malaria volunteer infection studies (IBSM-VIS) provide a unique opportunity ... ...

    Abstract Background: Malaria-associated anaemia, arising from symptomatic, asymptomatic and submicroscopic infections, is a significant cause of morbidity worldwide. Induced blood stage malaria volunteer infection studies (IBSM-VIS) provide a unique opportunity to evaluate the haematological response to early Plasmodium falciparum and Plasmodium vivax infection.
    Methods: This study was an analysis of the haemoglobin, red cell counts, and parasitaemia data from 315 participants enrolled in IBSM-VIS between 2012 and 2019, including 269 participants inoculated with the 3D7 strain of P. falciparum (Pf3D7), 15 with an artemisinin-resistant P. falciparum strain (PfK13) and 46 with P. vivax. Factors associated with the fractional fall in haemoglobin (Hb-FF) were evaluated, and the malaria-attributable erythrocyte loss after accounting for phlebotomy-related losses was estimated. The relative contribution of parasitized erythrocytes to the malaria-attributable erythrocyte loss was also estimated.
    Results: The median peak parasitaemia prior to treatment was 10,277 parasites/ml (IQR 3566-27,815), 71,427 parasites/ml [IQR 33,236-180,213], and 34,840 parasites/ml (IQR 13,302-77,064) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. The median Hb-FF was 10.3% (IQR 7.8-13.3), 14.8% (IQR 11.8-15.9) and 11.7% (IQR 8.9-14.5) in those inoculated with Pf3D7, PfK13 and P. vivax, respectively, with the haemoglobin nadir occurring a median 12 (IQR 5-21), 15 (IQR 7-22), and 8 (IQR 7-15) days following inoculation. In participants inoculated with P. falciparum, recrudescence was associated with a greater Hb-FF, while in those with P. vivax, the Hb-FF was associated with a higher pre-treatment parasitaemia and later day of anti-malarial treatment. After accounting for phlebotomy-related blood losses, the estimated Hb-FF was 4.1% (IQR 3.1-5.3), 7.2% (IQR 5.8-7.8), and 4.9% (IQR 3.7-6.1) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. Parasitized erythrocytes were estimated to account for 0.015% (IQR 0.006-0.06), 0.128% (IQR 0.068-0.616) and 0.022% (IQR 0.008-0.082) of the malaria-attributable erythrocyte loss in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively.
    Conclusion: Early experimental P. falciparum and P. vivax infection resulted in a small but significant fall in haemoglobin despite parasitaemia only just at the level of microscopic detection. Loss of parasitized erythrocytes accounted for < 0.2% of the total malaria-attributable haemoglobin loss.
    MeSH term(s) Adult ; Anemia/drug therapy ; Anemia/parasitology ; Antimalarials/therapeutic use ; Erythrocytes/parasitology ; Female ; Humans ; Malaria, Falciparum/complications ; Malaria, Falciparum/drug therapy ; Malaria, Falciparum/parasitology ; Malaria, Vivax/complications ; Malaria, Vivax/drug therapy ; Malaria, Vivax/parasitology ; Male ; Middle Aged ; Parasitemia/drug therapy ; Parasitemia/parasitology ; Plasmodium falciparum/drug effects ; Plasmodium vivax/drug effects ; Young Adult
    Chemical Substances Antimalarials
    Language English
    Publishing date 2021-12-20
    Publishing country England
    Document type Journal Article
    ISSN 1475-2875
    ISSN (online) 1475-2875
    DOI 10.1186/s12936-021-04003-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article ; Online: Serum MicroRNAs as Biomarkers in Hepatitis C: Preliminary Evidence of a MicroRNA Panel for the Diagnosis of Hepatocellular Carcinoma.

    Weis, Anna / Marquart, Louise / Calvopina, Diego A / Genz, Berit / Ramm, Grant A / Skoien, Richard

    International journal of molecular sciences

    2019  Volume 20, Issue 4

    Abstract: Early diagnosis of cirrhosis and hepatocellular carcinoma (HCC) due to chronic Hepatitis C (CHC) remain clinical priorities. In this pilot study, we assessed serum microRNA (miRNA) expression to distinguish cirrhosis and HCC, alone and in combination ... ...

    Abstract Early diagnosis of cirrhosis and hepatocellular carcinoma (HCC) due to chronic Hepatitis C (CHC) remain clinical priorities. In this pilot study, we assessed serum microRNA (miRNA) expression to distinguish cirrhosis and HCC, alone and in combination with the aminotransferase-to-platelet ratio (APRI), Fibrosis 4 (FIB-4), and alpha-fetoprotein (AFP). Sixty CHC patients were subdivided into 3 cohorts: Mild disease (fibrosis stage F0-2;
    MeSH term(s) Biomarkers, Tumor/blood ; Carcinoma, Hepatocellular/blood ; Carcinoma, Hepatocellular/genetics ; Carcinoma, Hepatocellular/virology ; Early Detection of Cancer ; Female ; Gene Expression Regulation, Neoplastic ; Hepacivirus/genetics ; Hepacivirus/pathogenicity ; Hepatitis C/blood ; Hepatitis C/genetics ; Hepatitis C/virology ; Humans ; Liver Cirrhosis/blood ; Liver Cirrhosis/virology ; Liver Neoplasms/blood ; Liver Neoplasms/genetics ; Liver Neoplasms/virology ; Male ; MicroRNAs/blood ; MicroRNAs/genetics ; Middle Aged
    Chemical Substances Biomarkers, Tumor ; MicroRNAs
    Language English
    Publishing date 2019-02-17
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms20040864
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Article: Longitudinal changes in iron homeostasis in human experimental and clinical malaria.

    Woolley, Stephen D / Grigg, Matthew J / Marquart, Louise / Gower, Jeremy / Piera, Kim / Nair, Arya Sheela / Amante, Fiona M / Rajahram, Giri S / William, Timothy / Frazer, David M / Chalon, Stephan / McCarthy, James S / Anstey, Nicholas M / Barber, Bridget E

    medRxiv : the preprint server for health sciences

    2023  

    Abstract: Background: The interaction between iron deficiency and malaria is incompletely understood. We evaluated longitudinal changes in iron homeostasis in volunteers enrolled in malaria volunteer infection studies (VIS) and in Malaysian patients with ... ...

    Abstract Background: The interaction between iron deficiency and malaria is incompletely understood. We evaluated longitudinal changes in iron homeostasis in volunteers enrolled in malaria volunteer infection studies (VIS) and in Malaysian patients with falciparum and vivax malaria.
    Methods: We retrieved samples and associated data from 55 participants enrolled in malaria VIS, and 171 malaria patients and 30 healthy controls enrolled in clinical studies in Malaysia. Ferritin, hepcidin, erythropoietin, and soluble transferrin receptor (sTfR) were measured by ELISA.
    Results: In the VIS, participants' parasitaemia was correlated with baseline mean corpuscular volume (MCV), but not iron status (ferritin, hepcidin or sTfR). Ferritin, hepcidin and sTfR all increased during the VIS. Ferritin and hepcidin normalised by day 28, while sTfR remained elevated. In VIS participants, baseline iron status (ferritin) was associated with post-treatment increases in liver transaminase levels. In Malaysian malaria patients, hepcidin and ferritin were elevated on admission compared to healthy controls, while sTfR increased following admission. Hepcidin normalised by day 28; however, ferritin and sTfR both remained elevated 4 weeks following admission.
    Conclusion: Our findings demonstrate that parasitaemia is associated with an individual's MCV rather than iron status. The persistent elevation in sTfR 4 weeks post-infection in both malaria VIS and clinical malaria may reflect a causal link between malaria and iron deficiency.
    Language English
    Publishing date 2023-12-21
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.12.19.23300265
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  6. Article ; Online: Incidence and Regression of Actinic Keratoses in Organ Transplant Recipients.

    Jiyad, Zainab / Marquart, Louise / O'Rourke, Peter / Green, Adèle C

    Acta dermato-venereologica

    2017  Volume 98, Issue 1, Page(s) 77–81

    Abstract: Actinic keratoses (AKs) are highly dynamic lesions and AK activity has been shown to be associated with squamous cell carcinoma (SCC). We sought to explore risk factors which may affect the 12-month turnover of AKs in organ transplant recipients (OTRs). ... ...

    Abstract Actinic keratoses (AKs) are highly dynamic lesions and AK activity has been shown to be associated with squamous cell carcinoma (SCC). We sought to explore risk factors which may affect the 12-month turnover of AKs in organ transplant recipients (OTRs). The number of incident AKs, regressed AKs and net change in AK counts were calculated. Negative binomial regression and Poisson regression models were used to estimate rate ratios (RR) for these 3 outcomes. Among 150 renal and 89 liver OTRs, those who spent > 50% of a typical weekday in the sun had a lower rate of AK regression than those who spent minimal time in the sun during a typical weekday. Age, parents' country of origin, hair colour, skin cancer history and recent AK treatment were all significantly associated with AK turnover. Clinically, these risk factors may be used to monitor OTRs at increased risk of SCC.
    MeSH term(s) Adult ; Aged ; Female ; Hair Color ; Humans ; Immunosuppression Therapy/adverse effects ; Incidence ; Keratosis, Actinic/epidemiology ; Keratosis, Actinic/therapy ; Kidney Transplantation/statistics & numerical data ; Liver Transplantation/statistics & numerical data ; Male ; Middle Aged ; Phenotype ; Remission, Spontaneous ; Risk Factors ; Sunlight/adverse effects ; Time Factors
    Language English
    Publishing date 2017-08-30
    Publishing country Sweden
    Document type Journal Article
    ZDB-ID 80007-7
    ISSN 1651-2057 ; 0001-5555
    ISSN (online) 1651-2057
    ISSN 0001-5555
    DOI 10.2340/00015555-2783
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  7. Article ; Online: Characterizing the Blood-Stage Antimalarial Activity of Tafenoquine in Healthy Volunteers Experimentally Infected With Plasmodium falciparum.

    Barber, Bridget E / Abd-Rahman, Azrin N / Webster, Rebecca / Potter, Adam J / Llewellyn, Stacey / Marquart, Louise / Sahai, Nischal / Leelasena, Indika / Birrell, Geoffrey W / Edstein, Michael D / Shanks, G Dennis / Wesche, David / Moehrle, Joerg J / McCarthy, James S

    Clinical infectious diseases : an official publication of the Infectious Diseases Society of America

    2023  Volume 76, Issue 11, Page(s) 1919–1927

    Abstract: Background: The long-acting 8-aminoquinoline tafenoquine may be a good candidate for mass drug administration if it exhibits sufficient blood-stage antimalarial activity at doses low enough to be tolerated by glucose 6-phosphate dehydrogenase (G6PD)- ... ...

    Abstract Background: The long-acting 8-aminoquinoline tafenoquine may be a good candidate for mass drug administration if it exhibits sufficient blood-stage antimalarial activity at doses low enough to be tolerated by glucose 6-phosphate dehydrogenase (G6PD)-deficient individuals.
    Methods: Healthy adults with normal levels of G6PD were inoculated with Plasmodium falciparum 3D7-infected erythrocytes on day 0. Different single oral doses of tafenoquine were administered on day 8. Parasitemia and concentrations of tafenoquine and the 5,6-orthoquinone metabolite in plasma/whole blood/urine were measured and standard safety assessments performed. Curative artemether-lumefantrine therapy was administered if parasite regrowth occurred, or on day 48 ± 2. Outcomes were parasite clearance kinetics, pharmacokinetic and pharmacokinetic/pharmacodynamic (PK/PD) parameters from modelling, and dose simulations in a theoretical endemic population.
    Results: Twelve participants were inoculated and administered 200 mg (n = 3), 300 mg (n = 4), 400 mg (n = 2), or 600 mg (n = 3) tafenoquine. The parasite clearance half-life with 400 mg or 600 mg (5.4 hours and 4.2 hours, respectively) was faster than with 200 mg or 300 mg (11.8 hours and 9.6 hours, respectively). Parasite regrowth occurred after dosing with 200 mg (3/3 participants) and 300 mg (3/4 participants) but not after 400 mg or 600 mg. Simulations using the PK/PD model predicted that 460 mg and 540 mg would clear parasitaemia by a factor of 106 and 109, respectively, in a 60-kg adult.
    Conclusions: Although a single dose of tafenoquine exhibits potent P. falciparum blood-stage antimalarial activity, the estimated doses to effectively clear asexual parasitemia will require prior screening to exclude G6PD deficiency. Clinical Trials Registration. Australian and New Zealand Clinical Trials Registry (ACTRN12620000995976).
    MeSH term(s) Adult ; Humans ; Antimalarials/adverse effects ; Plasmodium falciparum ; Healthy Volunteers ; Parasitemia/drug therapy ; Artemether/pharmacology ; Artemether/therapeutic use ; Artemether, Lumefantrine Drug Combination/therapeutic use ; Australia ; Malaria, Falciparum/drug therapy ; Malaria, Falciparum/parasitology
    Chemical Substances Antimalarials ; tafenoquine (262P8GS9L9) ; Artemether (C7D6T3H22J) ; Artemether, Lumefantrine Drug Combination
    Language English
    Publishing date 2023-02-06
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1099781-7
    ISSN 1537-6591 ; 1058-4838
    ISSN (online) 1537-6591
    ISSN 1058-4838
    DOI 10.1093/cid/ciad075
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  8. Article ; Online: The in-vivo dynamics of Plasmodium falciparum HRP2: implications for the use of rapid diagnostic tests in malaria elimination.

    Marquart, Louise / Webb, Lachlan / O'Rourke, Peter / Gatton, Michelle L / Hsiang, Michelle S / Kalnoky, Michael / Jang, Ihn Kyung / Ntuku, Henry / Mumbengegwi, Davis R / Domingo, Gonzalo J / McCarthy, James S / Britton, Sumudu

    Malaria journal

    2022  Volume 21, Issue 1, Page(s) 233

    Abstract: Background: Rapid diagnostic tests (RDTs) that rely on the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) have become key tools for diagnosing P. falciparum infection. The utility of RDTs can be limited by PfHRP2 persistence, ... ...

    Abstract Background: Rapid diagnostic tests (RDTs) that rely on the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) have become key tools for diagnosing P. falciparum infection. The utility of RDTs can be limited by PfHRP2 persistence, however it can be a potential benefit in low transmission settings where detection of persistent PfHRP2 using newer ultra-sensitive PfHRP2 based RDTs can serve as a surveillance tool to identify recent exposure. Better understanding of the dynamics of PfHRP2 over the course of a malaria infection can inform optimal use of RDTs.
    Methods: A previously published mathematical model was refined to mimic the production and decay of PfHRP2 during a malaria infection. Data from 15 individuals from volunteer infection studies were used to update the original model and estimate key model parameters. The refined model was applied to a cohort of patients from Namibia who received treatment for clinical malaria infection for whom longitudinal PfHRP2 concentrations were measured.
    Results: The refinement of the PfHRP2 dynamic model indicated that in malaria naïve hosts, P. falciparum parasites of the 3D7 strain produce 33.6 × 10
    Conclusions: The updated mathematical model can predict the growth and clearance of PfHRP2 during the production and decay of a mono-infection with P. falciparum, increasing the understanding of PfHRP2 antigen dynamics. This model can guide the optimal use of PfHRP2-based RDTs for reliable diagnosis of P. falciparum infection and re-infection in endemic settings, but also for malaria surveillance and elimination programmes in low transmission areas.
    MeSH term(s) Adult ; Antigens, Protozoan ; Diagnostic Tests, Routine ; Humans ; Malaria, Falciparum/epidemiology ; Models, Theoretical ; Namibia ; Plasmodium falciparum ; Protozoan Proteins
    Chemical Substances Antigens, Protozoan ; Protozoan Proteins
    Language English
    Publishing date 2022-08-03
    Publishing country England
    Document type Journal Article
    ZDB-ID 2091229-8
    ISSN 1475-2875 ; 1475-2875
    ISSN (online) 1475-2875
    ISSN 1475-2875
    DOI 10.1186/s12936-022-04245-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  9. Article ; Online: Assays for quantification of male and female gametocytes in human blood by qRT-PCR in the absence of pure sex-specific gametocyte standards.

    Wang, Claire Y T / Ballard, Emma / Llewellyn, Stacey / Marquart, Louise / Bousema, Teun / McCarthy, James S / Collins, Katharine A

    Malaria journal

    2020  Volume 19, Issue 1, Page(s) 218

    Abstract: Background: Malaria transmission from humans to Anopheles mosquitoes requires the presence of gametocytes in human peripheral circulation, and the dynamics of transmission are determined largely by the density and sex ratio of the gametocytes. Molecular ...

    Abstract Background: Malaria transmission from humans to Anopheles mosquitoes requires the presence of gametocytes in human peripheral circulation, and the dynamics of transmission are determined largely by the density and sex ratio of the gametocytes. Molecular methods are thus employed to measure gametocyte densities, particularly when assessing transmission epidemiology and the efficacy of transmission-blocking interventions. However, accurate quantification of male and female gametocytes with molecular methods requires pure male and female gametocytes as reference standards, which are not widely available.
    Methods: qRT-PCR assays were used to quantify levels of sex-specific mRNA transcripts in Plasmodium falciparum female and male gametocytes (pfs25 and pfMGET, respectively) using synthetic complimentary RNA standards and in vitro cultured gametocytes. Assays were validated and assay performance was investigated in blood samples of clinical trial participants using these standards and compared to absolute quantification by droplet digital PCR (ddPCR).
    Results: The number of transcript copies per gametocyte were determined to be 279.3 (95% CI 253.5-307.6) for the female-specific transcript pfs25, and 12.5 (95% CI 10.6-14.9) for the male-specific transcript pfMGET. These numbers can be used to convert from transcript copies/mL to gametocyte/mL. The reportable range was determined to be 5.71 × 10
    Conclusions: This study reports the validation of qRT-PCR assays that are able to accurately quantify female and male P. falciparum gametocytes at sub-microscopic densities. The assays showed excellent reproducibility, sensitivity, precision, specificity, and accuracy. The methodology will enable the estimation of gametocyte density in the absence of pure female and male gametocyte standards, and will facilitate clinical trials and epidemiological studies.
    MeSH term(s) Adult ; Blood/parasitology ; Humans ; Middle Aged ; Plasmodium falciparum/isolation & purification ; Real-Time Polymerase Chain Reaction/methods ; Reproducibility of Results ; Reverse Transcriptase Polymerase Chain Reaction ; Young Adult
    Language English
    Publishing date 2020-06-23
    Publishing country England
    Document type Journal Article
    ISSN 1475-2875
    ISSN (online) 1475-2875
    DOI 10.1186/s12936-020-03291-9
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  10. Article: Effect of Serotype and Strain Diversity on Dengue Virus Replication in Australian Mosquito Vectors.

    Ekwudu, O'mezie / Marquart, Louise / Webb, Lachlan / Lowry, Kym S / Devine, Gregor J / Hugo, Leon E / Frentiu, Francesca D

    Pathogens (Basel, Switzerland)

    2020  Volume 9, Issue 8

    Abstract: Dengue virus (DENV) is the most important mosquito-borne viral pathogen of humans, comprising four serotypes (DENV-1 to -4) with a myriad of genotypes and strains. The kinetics of DENV replication within the mosquito following ingestion of a blood meal ... ...

    Abstract Dengue virus (DENV) is the most important mosquito-borne viral pathogen of humans, comprising four serotypes (DENV-1 to -4) with a myriad of genotypes and strains. The kinetics of DENV replication within the mosquito following ingestion of a blood meal influence the pathogen's ability to reach the salivary glands and thus the transmission potential. The influence of DENV serotype and strain diversity on virus kinetics in the two main vector species,
    Language English
    Publishing date 2020-08-18
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2695572-6
    ISSN 2076-0817
    ISSN 2076-0817
    DOI 10.3390/pathogens9080668
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

To top