Reduced Plasmodium vivax Erythrocyte Infection in PNG Duffy-Negative Heterozygotes

BACKGROUND: Erythrocyte Duffy blood group negativity reaches fixation in African populations where Plasmodium vivax (Pv) is uncommon. While it is known that Duffy-negative individuals are highly resistant to Pv erythrocyte infection, little is known regarding Pv susceptibility among heterozygous carriers of a Duffy-negative allele (+/−). Our limited knowledge of the selective advantages or disadvantages associated with this genotype constrains our understanding of the effect that interventions against Pv may have on the health of people living in malaria-endemic regions. METHODS AND FINDINGS: We conducted cross-sectional malaria prevalence surveys in Papua New Guinea (PNG), where we have previously identified a new Duffy-negative allele among individuals living in a region endemic for all four human malaria parasite species. We evaluated infection status by conventional blood smear light microscopy and semi-quantitative PCR-based strategies. Analysis of a longitudinal cohort constructed from our surveys showed that Duffy heterozygous (+/−) individuals were protected from Pv erythrocyte infection compared to those homozygous for wild-type alleles (+/+) (log-rank tests: LM, p = 0.049; PCR, p = 0.065). Evaluation of Pv parasitemia, determined by semi-quantitative PCR-based methods, was significantly lower in Duffy +/− vs. +/+ individuals (Mann-Whitney U: p = 0.023). Overall, we observed no association between susceptibility to P. falciparum erythrocyte infection and Duffy genotype. CONCLUSIONS: Our findings provide the first evidence that Duffy-negative heterozygosity reduces erythrocyte susceptibility to Pv infection. As this reduction was not associated with greater susceptibility to Pf malaria, our in vivo observations provide evidence that Pv-targeted control measures can be developed safely

High sensitivity detection of Plasmodium species reveals positive correlations between infections of different species, shifts in age distribution and reduced local variation in Papua New Guinea

BACKGROUND: When diagnosed by standard light microscopy (LM), malaria prevalence can vary significantly between sites, even at local scale, and mixed species infections are consistently less common than expect in areas co-endemic for Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae. The development of a high-throughput molecular species diagnostic assay now enables routine PCR-based surveillance of malaria infections in large field and intervention studies, and improves resolution of species distribution within and between communities. METHODS: This study reports differences in the prevalence of infections with all four human malarial species and of mixed infections as diagnosed by LM and post-PCR ligase detection reaction-fluorescent microsphere (LDR-FMA) assay in 15 villages in the central Sepik area of Papua New Guinea. RESULTS: Significantly higher rates of infection by P. falciparum, P. vivax, P. malariae and Plasmodium ovale were observed in LDR-FMA compared to LM diagnosis (p > 0.001). Increases were particularly pronounced for P. malariae (3.9% vs 13.4%) and P. ovale (0.0% vs 4.8%). In contrast to LM diagnosis, which suggested a significant deficit of mixed species infections, a significant excess of mixed infections over expectation was detected by LDR-FMA (p > 0.001). Age of peak prevalence shifted to older age groups in LDR-FMA diagnosed infections for P. falciparum (LM: 7-9 yrs 47.5%, LDR-FMA: 10-19 yrs 74.2%) and P. vivax (LM: 4-6 yrs 24.2%, LDR-FMA: 7-9 yrs 50.9%) but not P. malariae infections (10-19 yrs, LM: 7.7% LDR-FMA: 21.6%). Significant geographical variation in prevalence was found for all species (except for LM-diagnosed P. falciparum), with the extent of this variation greater in LDR-FMA than LM diagnosed infections (overall, 84.4% vs. 37.6%). Insecticide-treated bednet (ITN) coverage was also the dominant factor linked to geographical differences in Plasmodium species infection prevalence explaining between 60.6% - 74.5% of this variation for LDR-FMA and 81.8% - 90.0% for LM (except P. falciparum), respectively. CONCLUSION: The present study demonstrates that application of molecular diagnosis reveals patterns of malaria risk that are significantly different from those obtained by standard LM. Results provide insight relevant to design of malaria control and eradication strategie

DNA Suspension Arrays: Silencing Discrete Artifacts for High-Sensitivity Applications

Detection of low frequency single nucleotide polymorphisms (SNPs) has important implications in early screening for tumorgenesis, genetic disorders and pathogen drug resistance. Nucleic acid arrays are a powerful tool for genome-scale SNP analysis, but detection of low-frequency SNPs in a mixed population on an array is problematic. We demonstrate a model assay for HIV-1 drug resistance mutations, wherein ligase discrimination products are collected on a suspension array. In developing this system, we discovered that signal from multiple polymorphisms was obscured by two discrete hybridization artifacts. Specifically: 1) tethering of unligated probes on the template DNA elicited false signal and 2) unpredictable probe secondary structures impaired probe capture and suppressed legitimate signal from the array. Two sets of oligonucleotides were used to disrupt these structures; one to displace unligated reporter labels from the bead-bound species and another to occupy sequences which interfered with array hybridization. This artifact silencing system resulted in a mean 21-fold increased sensitivity for 29 minority variants of 17 codons in our model assay for mutations most commonly associated with HIV-1 drug resistance. Furthermore, since the artifacts we characterized are not unique to our system, their specific inhibition might improve the quality of data from solid-state microarrays as well as from the growing number of multiple analyte suspension arrays relying on sequence-specific nucleic acid target capture

Daily egg consumption in hyperlipidemic adults - Effects on endothelial function and cardiovascular risk

<p>Abstract</p> <p>Background</p> <p>Limiting consumption of eggs, which are high in cholesterol, is generally recommended to reduce risk of cardiovascular disease. However, recent evidence suggests that dietary cholesterol has limited influence on serum cholesterol or cardiac risk.</p> <p>Objective</p> <p>To assess the effects of egg consumption on endothelial function and serum lipids in hyperlipidemic adults.</p> <p>Methods</p> <p>Randomized, placebo-controlled crossover trial of 40 hyperlipidemic adults (24 women, 16 men; average age = 59.9 ± 9.6 years; weight = 76.3 ± 21.8 kilograms; total cholesterol = 244 ± 24 mg/dL). In the acute phase, participants were randomly assigned to one of the two sequences of a single dose of three medium hardboiled eggs and a sausage/cheese breakfast sandwich. In the sustained phase, participants were then randomly assigned to one of the two sequences of two medium hardboiled eggs and 1/2 cup of egg substitute daily for six weeks. Each treatment assignment was separated by a four-week washout period. Outcome measures of interest were endothelial function measured as flow mediated dilatation (FMD) and lipid panel.</p> <p>Results</p> <p>Single dose egg consumption had no effects on endothelial function as compared to sausage/cheese (0.4 ± 1.9 vs. 0.4 ± 2.4%; <it>p </it>= 0.99). Daily consumption of egg substitute for 6 weeks significantly improved endothelial function as compared to egg (1.0 ± 1.2% vs. -0.1 ± 1.5%; <it>p </it>< 0.01) and lowered serum total cholesterol (-18 ± 18 vs. -5 ± 21 mg/dL; <it>p </it>< 0.01) and LDL (-14 ± 20 vs. -2 ± 19 mg/dL; <it>p </it>= 0.01). Study results (positive or negative) are expressed in terms of change relative to baseline.</p> <p>Conclusions</p> <p>Egg consumption was found to be non-detrimental to endothelial function and serum lipids in hyperlipidemic adults, while egg substitute consumption was beneficial.</p

Comparison of diagnostic methods for the detection and quantification of the four sympatric Plasmodium species in field samples from Papua New Guinea

Accurate diagnosis of Plasmodium infections is essential for malaria morbidity and mortality reduction in tropical areas. Despite great advantages of light microscopy (LM) for malaria diagnosis, its limited sensitivity is a critical shortfall for epidemiological studies. Robust molecular diagnostics tools are thus needed.; The present study describes the development of a duplex quantitative real time PCR (qPCR) assay, which specifically detects and quantifies the four human Plasmodium species. Performance of this method was compared to PCR-ligase detection reaction-fluorescent microsphere assay (PCR_LDR_FMA), nested PCR (nPCR) and LM, using field samples collected from 452 children one to five years of age from the Sepik area in Papua New Guinea. Agreement between diagnostic methods was calcualted using kappa statistics.; The agreement of qPCR with other molecular diagnostic methods was substantial for the detection of P. falciparum, but was moderate for the detection of P. vivax, P. malariae and P. ovale. P. falciparum and P. vivax prevalence by qPCR was 40.9% and 65.7% respectively. This compares to 43.8% and 73.2% by nPCR and 47.1% and 67.5% by PCR_LDR_FMA. P. malariae and P. ovale prevalence was 4.7% and 7.3% by qPCR, 3.3% and 3.8% by nPCR, and 7.7% and 4.4% by PCR_LDR_FMA. Prevalence by LM was lower for all four species, being 25.4% for P. falciparum, 54.9% for P. vivax, 2.4% for P. malariae and 0.0% for P. ovale. The quantification by qPCR closely correlated with microscopic quantification for P. falciparum and P. vivax samples (R2 = 0.825 and R2 = 0.505, respectively). The low prevalence of P. malariae and P. ovale did not permit a solid comparative analysis of quantification for these species.; The qPCR assay developed proved optimal for detection of all four Plasmodium species. Densities by LM were well reflected in quantification results by qPCR, whereby congruence was better for P. falciparum than for P. vivax. This likely is a consequence of the generally lower P. vivax densities. Easy performance of the qPCR assay, a less laborious workflow and reduced risk of contamination, together with reduced costs per sample through reduced reaction volume, opens the possibility to implement qPCR in endemic settings as a suitable diagnostic tool for large epidemiological studies

How Much Remains Undetected? Probability of Molecular Detection of Human Plasmodia in the Field

BACKGROUND: In malaria endemic areas, most people are simultaneously infected with different parasite clones. Detection of individual clones is hampered when their densities fluctuate around the detection limit and, in case of P. falciparum, by sequestration during part of their life cycle. This has important implications for measures of levels of infection or for the outcome of clinical trials. This study aimed at measuring the detectability of individual P. falciparum and P. vivax parasite clones in consecutive samples of the same patient and at investigating the impact of sampling strategies on basic epidemiological measures such as multiplicity of infection (MOI). METHODS: Samples were obtained in a repeated cross-sectional field survey in 1 to 4.5 years old children from Papua New Guinea, who were followed up in 2-monthly intervals over 16 months. At each follow-up visit, two consecutive blood samples were collected from each child at intervals of 24 hours. Samples were genotyped for the polymorphic markers msp2 for P. falciparum and msp1F3 and MS16 for P. vivax. Observed prevalence and mean MOI estimated from single samples per host were compared to combined data from sampling twice within 24 h. FINDINGS AND CONCLUSION: Estimated detectability was high in our data set (0.79 [95% CI 0.76-0.82] for P. falciparum and, depending on the marker, 0.61 [0.58-0.63] or 0.73 [0.71-0.75] for P. vivax). When genotyping data from sequential samples, collected 24 hours apart, were combined, the increase in measured prevalence was moderate, 6 to 9% of all infections were missed on a single day. The effect on observed MOI was more pronounced, 18 to 31% of all individual clones were not detected in a single bleed. Repeated sampling revealed little difference between detectability of P. falciparum and P. vivax

International Consortium for Health Outcome Measurement Set of Outcomes That Matter to People Living With Inflammatory Arthritis: Consensus From an International Working Group

© 2018, The Authors. Arthritis Care & Research published by Wiley Periodicals, Inc. on behalf of American College of Rheumatology. Objective: The implementation of value-based health care in inflammatory arthritis requires a standardized set of modifiable outcomes and risk-adjustment variables that is feasible to implement worldwide. Methods: The International Consortium for Health Outcomes Measurement (ICHOM) assembled a multidisciplinary working group that consisted of 24 experts from 6 continents, including 6 patient representatives, to develop a standard set of outcomes for inflammatory arthritis. The process followed a structured approach, using a modified Delphi process to reach consensus on the following decision areas: conditions covered by the set, outcome domains, outcome measures, and risk-adjustment variables. Consensus in areas 2 to 4 were supported by systematic literature reviews and consultation of experts. Results: The ICHOM Inflammatory Arthritis Standard Set covers patients with rheumatoid arthritis (RA), axial spondyloarthritis, psoriatic arthritis, and juvenile idiopathic arthritis (JIA). We recommend that outcomes regarding pain, fatigue, activity limitations, overall physical and mental health impact, work/school/housework ability and productivity, disease activity, and serious adverse events be collected at least annually. Validated measures for patient-reported outcomes were endorsed and linked to common reporting metrics. Age, sex at birth, education level, smoking status, comorbidities, time since diagnosis, and rheumatoid factor and anti-citrullinated protein antibody lab testing for RA and JIA should be collected as risk-adjustment variables. Conclusion: We present the ICHOM inflammatory arthritis Standard Set of outcomes, which enables health care providers to implement the value-based health care framework and compare outcomes that are important to patients with inflammatory arthritis

Multiplicity and Diversity of Plasmodium vivax Infections in a Highly Endemic Region in Papua New Guinea

Plasmodium vivax is highly endemic in the lowlands of Papua New Guinea and accounts for a large proportion of the malaria cases in children less than 5 years of age. We collected 2117 blood samples at 2-monthly intervals from a cohort of 268 children aged 1 to 4.5 years and estimated the diversity and multiplicity of P. vivax infection. All P. vivax clones were genotyped using the merozoite surface protein 1 F3 fragment (msp1F3) and the microsatellite MS16 as molecular markers. High diversity was observed with msp1F3 (HE = 88.1%) and MS16 (HE = 97.8%). Of the 1162 P. vivax positive samples, 74% harbored multi-clone infections with a mean multiplicity of 2.7 (IQR = 1–3). The multiplicity of P. vivax infection increased slightly with age (P = 0.02), with the strongest increase in very young children. Intensified efforts to control malaria can benefit from knowledge of the diversity and MOI both for assessing the endemic situation and monitoring the effects of interventions

Is consuming yoghurt associated with weight management outcomes? Results from a systematic review.

BACKGROUND: Yoghurt is part of the diet of many people worldwide and is commonly recognised as a 'health food'. Epidemiological studies suggest that yoghurt may be useful as part of weight management programs. In the absence of comprehensive systematic reviews, this systematic review investigated the effect of yoghurt consumption by apparently healthy adults on weight-related outcomes. METHODS: An extensive literature search was undertaken, as part of a wider scoping review, to identify yoghurt studies. A total of 13 631 records were assessed for their relevance to weight-related outcomes. RESULTS: Twenty-two publications were eligible according to the review protocol. Cohort studies (n=6) and cross-sectional studies (n=7) all showed a correlation between yoghurt and lower or improved body weight/composition. Six randomised controlled trials (RCTs) and one controlled trial had various limitations, including small size and short duration. One RCT showed significant effects of yoghurt on weight loss, but was confounded by differences in calcium intake. One trial showed nonsignificant weight gain and the remaining five trials showed nonsignificant weight losses that were greater in yoghurt consumers. CONCLUSIONS: Yoghurt consumption is associated with lower body mass index, lower body weight/weight gain, smaller waist circumference and lower body fat in epidemiological studies. RCTs suggest weight reduction effects, but do not permit determination of a cause-effect relationship. Well-controlled, adequately powered trials in research and community settings appear likely to identify a modest but beneficial effect of yoghurt consumption for prevention of weight gain and management of obesity. The ready availability of yoghurt (a nutrient-dense food) and its ease of introduction to most diets suggests that educating the public to eat yoghurt as part of a balanced and healthy diet may potentially contribute to improved public health. Future carefully designed RCTs could provide proof of principle and large community-based studies could determine the practical impact of yoghurt on body weight/composition