Selenium Vacancies and Synergistic Effect of Near- and Far-Field-Enabled Ultrasensitive Surface-Enhanced Raman-Scattering-Active Substrates for Malaria Detection.

Defect engineering with the active control of defect states brings remarkable enhancement on surface-enhanced Raman scattering (SERS) by magnifying semiconductor-molecule interaction. Such light-trapping architectures can increase the light path length, which promotes photon-analytes interactions and further improves the SERS sensitivity. However, by far the reported semiconductor SERS-active substrates based on these strategies are often nonuniform and commonly in the form of isolated laminates or random clusters, which limit their reliability and stability for practical applications. Herein, we develop self-grown single-crystalline "V-shape" SnSe2-x (SnSe1.5, SnSe1.75, SnSe2) nanoflake arrays (SnSe2-x NFAs) with controlled selenium vacancies over large-area (10 cm × 10 cm) for ultrahigh-sensitivity SERS. First-principles density functional theory (DFT) is used to calculate the band gap and the electronic density of states (DOS). Based on the Herzberg-Teller theory regarding the vibronic coupling, the results of theoretical calculation reveal that the downshift of band edge and high DOS of SnSe1.75 can effectively enhance the vibronic coupling within the SnSe1.75-R6G system, which in turn enhances the photoinduced charge transfer resonance and contributes to the SERS activity with a remarkable enhancement factor of 1.68 × 107. Furthermore, we propose and demonstrate ultrasensitive (10-15 M for R6G), uniform, and reliable SERS substrates by forming SnSe1.75 NFAs/Au heterostructures via a facile Au evaporation process. We attribute the superior performance of our SnSe1.75 NFAs/Au heterostructures to the following reasons: (1) selenium vacancies and (2) synergistic effect of the near and far fields. In addition, we successfully build a detection platform to achieve rapid (∼15 min for the whole process), antibody-free, in situ, and reliable early malaria detection (100% detection rate for 10 samples with 160 points) in whole blood, and molecular hemozoin (<100/mL) can be detected. Our approach not only provides an efficient technique to obtain large-area, uniform, and reliable SERS-active substrates but also offers a substantial impact on addressing practical issues in many application scenarios such as the detection of insect-borne infectious diseases.

Prevalence and association of malaria with ABO blood group and hemoglobin level in individuals visiting Mekaneeyesus Primary Hospital, Estie District, northwest Ethiopia: a cross-sectional study.

Malaria is a serious and sometimes fatal mosquito-borne disease caused by protozoan parasite of the genus Plasmodium. ABO blood group antigens represent polymorphic traits inherited among individuals and populations. Differences in blood group antigen expression can increase or decrease host susceptibility to many infections. This study was undertaken to determine the prevalence of malaria and its possible association with ABO blood group and hemoglobin level among individuals attending Mekaneeyesus Primary Hospital, Estie District, northwestern Ethiopia. Sociodemographic variables and relevant data were collected from 390 randomly selected individuals through structured questionnaire. Then, thick and thin smears were prepared from finger pricked blood samples, stained, and examined microscopically for detection and identification of malaria parasites. ABO blood group and hemoglobin levels of the same subjects were also determined. The data generated were analyzed for descriptive and logistic regression models. Variables with p value < 0.05 in multivariable logistic regression were considered explanatory variables. The overall prevalence of malaria was 8.5%; Plasmodium vivax (5.6%) was the most predominant, followed by P. falciparum (2.3%), and mixed infection of the two species (0.5%). In our study, being male (AOR = 3.48), under-five years of age (AOR = 72.84), rural residence (AOR = 2.64), and failing to use bed net (AOR =4.65) were significantly associated with the risk of malaria. Most (14.6%) of malaria-positive cases were among individuals with blood group "A," while the least numbers of cases were among subjects with blood group "O." Individuals with blood group "A" were about four times at risk of malaria as compared to individuals with blood group "O" (AOR= 3.74). The prevalence of anemia was 23.1% and significantly associated with malaria (p<0.05). Prevalence of malaria in this study is still higher compared to some of previous reports from Ethiopia. Thus, there is a need to intensify effort in malaria prevention among potentially at risk segments of population, including males, rural residents, and under-five children, and promotion of ITNs use in the community. Supplementation of iron-rich diet for iron-deficient anemia people is needed. Further in-depth investigation is also necessary to clearly establish the role that ABO blood group plays in malaria.

Chemoprotective antimalarials identified through quantitative high-throughput screening of Plasmodium blood and liver stage parasites.

The spread of Plasmodium falciparum parasites resistant to most first-line antimalarials creates an imperative to enrich the drug discovery pipeline, preferably with curative compounds that can also act prophylactically. We report a phenotypic quantitative high-throughput screen (qHTS), based on concentration-response curves, which was designed to identify compounds active against Plasmodium liver and asexual blood stage parasites. Our qHTS screened over 450,000 compounds, tested across a range of 5 to 11 concentrations, for activity against Plasmodium falciparum asexual blood stages. Active compounds were then filtered for unique structures and drug-like properties and subsequently screened in a P. berghei liver stage assay to identify novel dual-active antiplasmodial chemotypes. Hits from thiadiazine and pyrimidine azepine chemotypes were subsequently prioritized for resistance selection studies, yielding distinct mutations in P. falciparum cytochrome b, a validated antimalarial drug target. The thiadiazine chemotype was subjected to an initial medicinal chemistry campaign, yielding a metabolically stable analog with sub-micromolar potency. Our qHTS methodology and resulting dataset provides a large-scale resource to investigate Plasmodium liver and asexual blood stage parasite biology and inform further research to develop novel chemotypes as causal prophylactic antimalarials.

Quantification of malaria antigens PfHRP2 and pLDH by quantitative suspension array technology in whole blood, dried blood spot and plasma.

BACKGROUND: Malaria diagnostics by rapid diagnostic test (RDT) relies primarily on the qualitative detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) and Plasmodium spp lactate dehydrogenase (pLDH). As novel RDTs with increased sensitivity are being developed and implemented as point of care diagnostics, highly sensitive laboratory-based assays are needed for evaluating RDT performance. Here, a quantitative suspension array technology (qSAT) was developed, validated and applied for the simultaneous detection of PfHRP2 and pLDH in a variety of biological samples (whole blood, plasma and dried blood spots) from individuals living in different endemic countries. RESULTS: The qSAT was specific for the target antigens, with analytical ranges of 6.8 to 762.8 pg/ml for PfHRP2 and 78.1 to 17076.6 pg/ml for P. falciparum LDH (Pf-LDH). The assay detected Plasmodium vivax LDH (Pv-LDH) at a lower sensitivity than Pf-LDH (analytical range of 1093.20 to 187288.5 pg/ml). Both PfHRP2 and pLDH levels determined using the qSAT showed to positively correlate with parasite densities determined by quantitative PCR (Spearman r = 0.59 and 0.75, respectively) as well as microscopy (Spearman r = 0.40 and 0.75, respectively), suggesting the assay to be a good predictor of parasite density. CONCLUSION: This immunoassay can be used as a reference test for the detection and quantification of PfHRP2 and pLDH, and could serve for external validation of RDT performance, to determine antigen persistence after parasite clearance, as well as a complementary tool to assess malaria burden in endemic settings.

Quantitative imaging of intraerythrocytic hemozoin by transient absorption microscopy.

Hemozoin, the heme detoxification end product in malaria parasites during their growth in the red blood cells (RBCs), serves as an important marker for diagnosis and treatment target of malaria disease. However, the current method for hemozoin-targeted drug screening mainly relies on in vitro ß-hematin inhibition assays, which may lead to false-positive events due to under-representation of the real hemozoin crystal. Quantitative in situ imaging of hemozoin is highly desired for high-throughput screening of antimalarial drugs and for elucidating the mechanisms of antimalarial drugs. We present transient absorption (TA) imaging as a high-speed single-cell analysis platform with chemical selectivity to hemozoin. We first demonstrated that TA microscopy is able to identify ß-hematin, the artificial form of hemozoin, from the RBCs. We further utilized time-resolved TA imaging to in situ discern hemozoin from malaria-infected RBCs with optimized imaging conditions. Finally, we quantitatively analyzed the hemozoin amount in RBCs at different infection stages by single-shot TA imaging. These results highlight the potential of TA imaging for efficient antimalarial drug screening and drug mechanism investigation.

Determining the Mode of Action of Antimalarial Drugs Using Time-Resolved LC-MS-Based Metabolite Profiling.

Methods for assessing the mode of action of new antimalarial compounds identified in high throughput phenotypic screens are needed to triage and facilitate lead compound development and to anticipate potential resistance mechanisms that might emerge. Here we describe a mass spectrometry-based approach for detecting metabolic changes in asexual erythrocytic stages of Plasmodium falciparum induced by antimalarial compounds. Time-resolved or concentration-resolved measurements are used to discriminate between putative targets of the compound and nonspecific and/or downstream secondary metabolic effects. These protocols can also be coupled with 13C-stable-isotope tracing experiments under nonequilibrative (or nonstationary) conditions to measure metabolic dynamics following drug exposure. Time-resolved 13C-labeling studies greatly increase confidence in target assignment and provide a more comprehensive understanding of the metabolic perturbations induced by small molecule inhibitors. The protocol provides details on the experimental design, Plasmodium falciparum culture, sample preparation, analytical approaches, and data analysis used in either targeted (pathway focused) or untargeted (all detected metabolites) analysis of drug-induced metabolic perturbations.

Malaria causes long-term effects on markers of iron status in children: a critical assessment of existing clinical and epidemiological tools.

BACKGROUND: Most epidemiological studies on the interplay between iron deficiency and malaria risk classify individuals as iron-deficient or iron-replete based on inflammation-dependent iron markers and adjustment for inflammation by using C-reactive protein (CRP) or α-1-acid glycoprotein (AGP). The validity of this approach and the usefulness of fibroblast growth factor 23 (FGF23) as a proposed inflammation-independent iron marker were tested. METHODS: Conventional iron markers and FGF23 were measured in children with acute falciparum malaria and after 1, 2, 4, and 6 weeks. Children, who were transfused or received iron supplementation in the follow-up period, were excluded, and iron stores were considered to be stable throughout. Ferritin levels 6 weeks after admission were used as a reference for admission iron status and compared with iron markers at different time points. RESULTS: There were long-term perturbations in iron markers during convalescence from acute malaria. None of the tested iron parameters, including FGF23, were independent of inflammation. CRP and AGP normalized faster than ferritin after malaria episodes. CONCLUSION: Malaria may bias epidemiological studies based on inflammation-dependent iron markers. Better markers of iron status during and after inflammation are needed in order to test strategies for iron supplementation in populations at risk of malaria.

In vitro effects of co-incubation of blood with artemether/lumefantrine & vitamin C on the viscosity & elasticity of blood.

BACKGROUND & OBJECTIVES: The antimalarial combination drug artemether/lumefantrine has been shown to be effective against malaria parasite through its haemolytic action. This drug is sometimes co-administered with vitamin C in patients with malaria. Vitamin C is associated with antioxidant properties which would be expected to protect against haemolytic effects of this antimalarial drug. This study was designed to investigate in vitro effects of co-incubation of artemether/lumefantrine with vitamin C on the viscosity and elasticity of blood. METHODS: Blood was collected from 12 healthy female volunteers with normal haemoglobin genotype (HbAA). A Bioprofiler was used to measure the viscosity and elasticity of untreated blood samples (control) and samples exposed to artemether/lumefantrine (0.06/0.36 mg/ml) alone and with low or high dose vitamin C (equivalent to adult doses of 100 or 500 mg). RESULTS: artemether/lumefantrine significantly (p<0.05) reduced viscosity of blood from 4.72 ± 0.38 to 3.78 ± 0.17 mPa.s. Addition of vitamin C (500 mg) further reduced blood viscosity to 2.67 ± 0.05 mPa.s. The elasticity of blood was significantly (p<0.05) reduced from 0.33 ± 0.04 mPa.s to 0.24 ± 0.03 mPa.s by the antimalarial drug, and further reduced to 0.13 ± 0.02 mPa.s in the presence of vitamin C (500 mg). INTERPRETATION & CONCLUSIONS: Co-incubation of blood with vitamin C and antimalarial combination drug potentiates the haemolytic effects of the latter on reducing blood viscosity and elasticity in vitro. This may possibly have implications in relation to haemolysis in patients receiving vitamin C supplementation with artemether/lumefantrine during malaria therapy.

Evaluation of the Antiplasmodial Activity and Lethality of the Leaf Extract of Cassia alata L. (Fabaceae).

OBJECTIVE: Cassia alata L. (Fabaceae), one of the three plants contained in Saye, a polyherbal antimalarial remedy was assessed for its antimalarial potential and safety in mice. METHODOLOGY: Organic extracts were prepared from the leaves and tested on the D 10 chloroquine-sensitive strain of Plasmodium falciparum using the parasite lactate dehydrogenase assay. The 4 days suppressive test using Plasmodium berghei in mice was used to evaluate the in vivo antiplasmodial activity of the extracts. Animals were treated by oral route, once a day with 50, 100, 250 and 400 mg kg -1 b.wt., of the extracts. The acute toxicity of the extracts was assessed in mice according to Thompson and Weil method. The lethal effects of the extracts on animal's body weight, tissues, biochemical and haematological parameters were determined at 823.5, 1235.5, 1853 and 2779.5 mg kg -1 b.wt., respectively. RESULTS: The dichloromethane/methane (1:1, v/v) extract of Cassia alata was the most active against Plasmodium falciparum. The mean percent suppression of parasitemia in mice was equal to 22.5, 41.8 and 45.2% at 50, 250 and 400 mg kg -1 b.wt., respectively. No death and no clinically significant changes were recorded in mice. The maximum non-lethal dose was more than 16875 mg kg -1 in animals. No significant changes were observed in body weight, tissues morphology, biochemical and hematological parameters at doses above or equal to 2779.5 mg kg -1 b.wt. CONCLUSION: The dichloromethane/methanol leaf extract of Cassia alata had a good to moderate in vitro and in vivo antiplasmodial activity and was found to have low toxicity at high doses in tested animals.

Malaria and Age Variably but Critically Control Hepcidin Throughout Childhood in Kenya.

Both iron deficiency (ID) and malaria are common among African children. Studies show that the iron-regulatory hormone hepcidin is induced by malaria, but few studies have investigated this relationship longitudinally. We measured hepcidin concentrations, markers of iron status, and antibodies to malaria antigens during two cross-sectional surveys within a cohort of 324 Kenyan children ≤ 8 years old who were under intensive surveillance for malaria and other febrile illnesses. Hepcidin concentrations were the highest in the youngest, and female infants, declined rapidly in infancy and more gradually thereafter. Asymptomatic malaria and malaria antibody titres were positively associated with hepcidin concentrations. Recent episodes of febrile malaria were associated with high hepcidin concentrations that fell over time. Hepcidin concentrations were not associated with the subsequent risk of either malaria or other febrile illnesses. Given that iron absorption is impaired by hepcidin, our data suggest that asymptomatic and febrile malaria contribute to the high burden of ID seen in African children. Further, the effectiveness of iron supplementation may be sub-optimal in the presence of asymptomatic malaria. Thus, strategies to prevent and eliminate malaria may have the added benefit of addressing an important cause of ID for African children.

The cytoplasmic prolyl-tRNA synthetase of the malaria parasite is a dual-stage target of febrifugine and its analogs.

The emergence of drug resistance is a major limitation of current antimalarials. The discovery of new druggable targets and pathways including those that are critical for multiple life cycle stages of the malaria parasite is a major goal for developing next-generation antimalarial drugs. Using an integrated chemogenomics approach that combined drug resistance selection, whole-genome sequencing, and an orthogonal yeast model, we demonstrate that the cytoplasmic prolyl-tRNA (transfer RNA) synthetase (PfcPRS) of the malaria parasite Plasmodium falciparum is a biochemical and functional target of febrifugine and its synthetic derivative halofuginone. Febrifugine is the active principle of a traditional Chinese herbal remedy for malaria. We show that treatment with febrifugine derivatives activated the amino acid starvation response in both P. falciparum and a transgenic yeast strain expressing PfcPRS. We further demonstrate in the Plasmodium berghei mouse model of malaria that halofuginol, a new halofuginone analog that we developed, is active against both liver and asexual blood stages of the malaria parasite. Halofuginol, unlike halofuginone and febrifugine, is well tolerated at efficacious doses and represents a promising lead for the development of dual-stage next-generation antimalarials.

The association between malaria and iron status or supplementation in pregnancy: a systematic review and meta-analysis.

INTRODUCTION: Malaria prevention and iron supplementation are associated with improved maternal and infant outcomes. However, evidence from studies in children suggests iron may adversely modify the risk of malaria. We reviewed the evidence in pregnancy of the association between malaria and markers of iron status, iron supplementation or parenteral treatment. METHODS AND FINDINGS: We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, the Global Health Library, and the Malaria in Pregnancy library to identify studies that investigated the association between iron status, iron treatment or supplementation during pregnancy and malaria. Thirty one studies contributed to the analysis; 3 experimental and 28 observational studies. Iron supplementation was not associated with an increased risk of P. falciparum malaria during pregnancy or delivery in Africa (summary Relative Risk = 0.89, 95% Confidence Interval (CI) 0.66-1.20, I(2) = 78.8%, 5 studies). One study in Asia reported an increased risk of P. vivax within 30 days of iron supplementation (e.g. adjusted Hazard Ratio = 1.75, 95% CI 1.14-2.70 for 1-15 days), but not after 60 days. Iron deficiency (based on ferritin and C-reactive protein) was associated with lower odds for malaria infection (summary Odds Ratio = 0.35, 0.24-0.51, I(2) = 59.2%, 5 studies). With the exception of the acute phase protein ferritin, biomarkers of iron deficiency were generally not associated with malaria infection. CONCLUSIONS: Iron supplementation was associated with a temporal increase in P vivax, but not with an increased risk of P. falciparum; however, data are insufficient to rule out the potential for an increased risk of P. falciparum. Iron deficiency was associated with a decreased malaria risk in pregnancy only when measured with ferritin. Until there is more evidence, it is prudent to provide iron in combination with malaria prevention during pregnancy.

Iron supplementation in HIV-infected Malawian children with anemia: a double-blind, randomized, controlled trial.

BACKGROUND: It is unknown whether iron supplementation in human immunodeficiency virus (HIV)-infected children living in regions with high infection pressure is safe or beneficial. A 2-arm, double-blind, randomized, controlled trial was conducted to examine the effects of iron supplementation on hemoglobin, HIV disease progression, and morbidity. METHODS: HIV-infected Malawian children aged 6-59 months with moderate anemia (hemoglobin level, 7.0-9.9 g/dL) were randomly assigned to receive 3 mg/kg/day of elemental iron and multivitamins (vitamins A, C, and D) or multivitamins alone for 3 months. Participants were followed for 6 months. RESULTS: A total of 209 children were randomly assigned to treatment, and 196 (93.8%) completed 6 months of follow-up. Iron supplementation was associated with greater increases in hemoglobin concentrations (adjusted mean difference [aMD], 0.60; 95% confidence interval [CI], .06-1.13; P = .03) and reduced the risk of anemia persisting for up to 6 months follow-up (adjusted prevalence ratio, 0.59; 95% CI, .38-.92; P = .02). Children who received iron had a better CD4 percentage response at 3 months (aMD, 6.00; 95% CI, 1.84-10.16; P = .005) but an increased incidence of malaria at 6 months (incidence rate, 120.2 vs 71.7; adjusted incidence rate ratio [aIRR], 1.81 [95% CI, 1.04-3.16]; P = .04), especially during the first 3 months (incidence rate, 78.1 vs 36.0; aIRR, 2.68 [95% CI, 1.08-6.63]; P = .03). CONCLUSIONS: Iron supplementation in anemic HIV-infected children has beneficial effects on hemoglobin, anemia, and immunity but increases the risk of malaria. Thus, iron supplementation in HIV-infected children living in malaria-endemic areas should only be provided in combination with adequate protection from malaria. CLINICAL TRIALS REGISTRATION: ISRCTN-62947977.

Hepcidin demonstrates a biphasic association with anemia in acute Plasmodium falciparum malaria.

Hepcidin levels are high and iron absorption is limited in acute malaria. The mechanism(s) that regulate hepcidin secretion remain undefined. We have measured hepcidin concentration and cytokines in 100 Kenyan children with acute falciparum malaria and different degrees of anemia. Hepcidin was increased on admission and fell significantly one week and one month after treatment. The association of hepcidin with hemoglobin was not linear and hepcidin was very low in severe malarial anemia. Parasite density, IL-10 and IL-6 were significantly associated with hepcidin concentration. Hepcidin response to acute malaria supports the notion of iron sequestration during acute malaria infection and suggests that iron administration during acute malaria is futile. These data suggest iron supplementation policies should take into account the high hepcidin levels and probable poor utilization of iron for up to one week after treatment for the majority of patients with acute malaria.

In vivo and in vitro antimalarial activity of 4-nerolidylcatechol.

4-Nerolidylcatechol (4-NC) isolated from Piper peltatum L. (Piperaceae) was evaluated for in vitro antiplasmodial activity against Plasmodium falciparum (cultures of both standard CQR (K1) and CQS (3D7) strains and two Amazonian field isolates) and for in vivo antimalarial activity using the Plasmodium berghei-murine model. 4-NC exhibits significant in vitro and moderate in vivo antiplasmodial activity. 4-NC administered orally and subcutaneously at doses of 200, 400 and 600 mg/kg/day suppressed the growth of P. berghei by up to 63% after four daily treatments (days 1-4). Also, 4-NC exhibited important in vitro antiplasmodial activity against both standard and field P. falciparum strains in which 50% inhibition of parasite growth (IC(50) ) was produced at concentrations of 0.05-2.11 µg/mL and depended upon the parasite strain. Interestingly, healthy (non-infected) mice that received 4-NC orally presented (denatured) blood plasma which exhibited significant in vitro activity against P. falciparum. This is evidence that mouse metabolism allows 4-NC or active metabolites to enter the blood. Further chemical and pharmacological studies are necessary to confirm the potential of 4-NC as a new antimalarial prototype.

Increased serum hepcidin and alterations in blood iron parameters associated with asymptomatic P. falciparum and P. vivax malaria.

BACKGROUND: Asymptomatic Plasmodium spp. infections and anemia are highly prevalent conditions in tropical regions. We studied whether asymptomatic parasitemia induces hepcidin- and/or cytokine-mediated iron maldistribution and anemia. DESIGN AND METHODS: A group of 1197 Indonesian schoolchildren, aged 5-15 years, were screened by microscopy for the presence of parasitemia. Concentrations of hemoglobin, serum hepcidin and parameters of iron status and inflammation were determined at baseline and 4 weeks after antimalarial treatment. RESULTS: Asymptomatic P. falciparum and P. vivax parasitemia were detected in 73 (6.1%) and 18 (1.5%) children, respectively, of whom 84% and 83% had a C-reactive protein concentration below 5 mg/L. Children with P. falciparum or P. vivax parasitemia had significantly lower hemoglobin concentrations than 17 aparasitemic controls (12.6 and 12.2 g/dL versus 14.4 g/dL; P<0.01), together with significantly higher serum hepcidin concentrations (5.2 and 5.6 nM versus 3.1 nM; P<0.05). The latter was associated with signs of iron maldistribution with higher ferritin concentrations and lower values of serum iron concentration, transferrin saturation and erythrocyte mean cell volume. Concentrations of growth differentiation factor 15 were similar across groups. Antimalarial treatment partly reversed these abnormalities and led to a significant increase in hemoglobin concentration. CONCLUSIONS: Asymptomatic malarial parasitemia is associated with increased hepcidin concentrations and anemia, in the absence of a manifest acute phase response. Prolonged iron maldistribution may be an underestimated cause of anemia. Screening for parasitemia should be performed before starting iron supplementation, as iron therapy may be less effective and even hazardous in these circumstances.

Mild increases in serum hepcidin and interleukin-6 concentrations impair iron incorporation in haemoglobin during an experimental human malaria infection.

The correct selection of individuals who will benefit from iron supplements in malaria-endemic regions requires improved insight in the effects of malaria on host iron homeostasis and innovative biomarkers. We assessed sequential changes in serum hepcidin and in traditional biochemical iron status indicators during an experimental Plasmodium falciparum malaria infection with five adult volunteers. The haemoglobin content of reticulocytes (Ret-H(e)) and of mature red blood cells (RBC-H(e)) represented iron incorporation into haemoglobin. Low-density parasitaemia and its treatment induced a mild increase in interleukin (IL)-6 and serum hepcidin concentrations. Despite this only mild increase, a marked hypoferraemia with a strong increase in serum ferritin concentrations developed, which was associated with a sharp fall in Ret-H(e), while RBC-H(e) remained unchanged. The ratio of soluble transferrin receptor (sTfR) to log ferritin concentrations decreased to an average nadir of 63% of the baseline value. We concluded that even mild increases in serum hepcidin and IL-6 concentrations result in a disturbed host iron homeostasis. Serum hepcidin, Ret-H(e) and Delta-H(e) (Ret-H(e) minus RBC-H(e)) are promising biomarkers to select those individuals who will benefit from iron supplements in malaria endemic regions, while the sTfR/log ferritin ratio should be used with caution to assess iron status during malaria.

[Changes in retinol, hemoglobin and ferritin concentrations in Colombian children with malaria]. / Cambios en las concentraciones de retinol, hemoglobina y ferritina en niños palúdicos colombianos.

INTRODUCTION: Malaria, anemia and intestinal parasitism can co-exist in certain populations of Colombian children. The effects of retinol supplementation and anti-intestinal parasite treatment in children with malaria is unknown. Changes after this treatment of with respect to hemoglobin, retinol, ferritin and C reactive protein levels have not been previously monitored. OBJECTIVE: The effect of simultaneous intervention with antimalarial, retinol supplementation and anti-intestinal parasites treatment will be monitored by examining levels of hemoglobin, ferritin, retinol and C reactive protein in children with malaria. MATERIALS AND METHODS: A non-blind experimental study was conducted in 93 children with malaria, aged 4-10 years. Each was randomly allocated to one of the following groups: (1) treatment with antimalarial and retinol supplement (Group MA); (2) treatment with antimalarialretinol supplement and anti-parasitic drug (Group MAP); (3) treatment with antimalarial and antiparasitic drug (Group MP), and (4) treatment only with antimalarials (Group M). The groups were observed for 30 days, with haemoglobin, ferritin, retinol and C reactive protein evaluated on days 0, 8 and 30 after treatment. RESULTS: Mean values for the children at day 0 were as follows: hemoglobin 10.3 +/- 1.6 g/dL, retinol 19.1 +/- 6.0 microg/dL, C reactive protein 75 +/- 63 mg/L and ferritin 213 +/- 203 microg/L. On day 30 after treatment, hemoglobin and plasma retinol concentrations increased in 1.4 +/- 1.4 g/dL and 11.5 +/- 8.1 microg/dL, whereas the C reactive protein and ferritin concentrations decreased to 66 +/- 60 mg/L, and 184 +/- 203 microg/L, respectively. No statistically significant differences appeared among the groups. On day 8, significant differences between the groups were observed in hemoglobin concentrations Group MAP was higher when compared to other groups. CONCLUSION: On day 30, hemoglobin and retinol were high, whereas C reactive protein was low. Simultaneous administration of a retinol supplement and anti-parasite treatment prevented hemoglobin reduction observed on day 8 without changes in other variables.

Miniaturization of a high-throughput pLDH-based Plasmodium falciparum growth inhibition assay for small volume samples from preclinical and clinical vaccine trials.

To date, no immune correlates for blood stage-specific immunity against Plasmodium falciparum malaria parasites have been identified. Growth and/or invasion inhibition assays using sera from Phase 2a/b trials will aid in determining whether correlations with protective immunity can be established for these assays. A major constraint in the ability to evaluate functional antibody activities from populations in endemic areas is the relatively limited availability of sufficient sample quantity. For this reason, we developed a miniaturized and high-throughput method to measure growth inhibitory activity by quantification of parasite lactate dehydrogenase (pLDH) in a 384-microtiter plate format. This culture method can be extended beyond the pLDH-based readout to other techniques commonly used to determine growth/invasion inhibition.