Concentration of Plasmodium falciparum gametocytes in whole blood samples by magnetic cell sorting enhances parasite infection rates in mosquito feeding assays.

BACKGROUND: Mosquito-feeding assays are important tools to guide the development and support the evaluation of transmission-blocking interventions. These functional bioassays measure the sporogonic development of gametocytes in blood-fed mosquitoes. Measuring the infectivity of low gametocyte densities has become increasingly important in malaria elimination scenarios. This will pose challenges to the sensitivity and throughput of existing mosquito-feeding assay protocols. Here, different gametocyte concentration methods of blood samples were explored to optimize conditions for detection of positive mosquito infections. METHODS: Mature gametocytes of Plasmodium falciparum were diluted into whole blood samples of malaria-naïve volunteers. Standard centrifugation, Percoll gradient, magnetic cell sorting (MACS) enrichment were compared using starting blood volumes larger than the control (direct) feed. RESULTS: MACS gametocyte enrichment resulted in the highest infection intensity with statistically significant increases in mean oocyst density in 2 of 3 experiments (p = 0.0003; p ≤ 0.0001; p = 0.2348). The Percoll gradient and standard centrifugation procedures resulted in variable infectivity. A significant increase in the proportion of infected mosquitoes and oocyst density was found when larger volumes of gametocyte-infected blood were used with the MACS procedure. CONCLUSIONS: The current study demonstrates that concentration methods of P. falciparum gametocyte-infected whole blood samples can enhance transmission in mosquito-feeding assays. Gametocyte purification by MACS was the most efficient method, allowing the assessment of gametocyte infectivity in low-density gametocyte infections, as can be expected in natural or experimental conditions

Predictors of functional outcome following femoral neck fractures treated with an arthroplasty: limitations of the Harris hip score

Introduction To study the association between potential prognostic factors and functional outcome at 1 and 5 year follow-up in patients with femoral neck fractures treated with an arthroplasty. To analyze the reliability of the Harris hip score (HHS). Materials and methods A multicenter analysis which included 252 patients who sustained a femoral neck fracture treated with an arthroplasty. Functional outcome after surgery was assessed using a modified HHS and was evaluated after 1 (HHS1) and 5 (HHS5) years. Several prognostic factors were analyzed and reliability of the HHS was assessed. Results After 1 year the presence of co-morbidities was a significant (p = 0.002) predictor for a poor functional outcome (mean HHS1 71.8 with co-morbidities, and 80.6 without co-morbidities). After 5 years none of the potential prognostic factors had significant influence on functional outcome. Internal consistency testing of the HHS showed that when pain and function of the HHS were analyzed together, the internal consistency was poor (HHS1 0.38 and HHS5 0.20). The internal consistency of the HHS solely in function (without pain) improved to 0.68 (HHS1) and 0.46 (HHS5). Analyzing the functional aspect exclusively, age and the existence of co-morbidities could be defined as predictors for functional outcome of femoral neck fractures after 1 and 5 years. Conclusion After using the HHS in a modification, age and the existence of pre-operative co-morbidities appeared to be predictors of the functional outcome after 1 and 5 years. The HHS, omitting pain, is a more reliable score to estimate the functional outcome, than HHS analyzing pain and function in one scoring syste

Neurological Adverse Effects Attributable to β-Lactam Antibiotics: A Literature Review

International audienc