Performance characteristics of combinations of host biomarkers to identify women with occult placental malaria: a case-control study from Malawi

Background

Because of its propensity to sequester in the placental intervillous space, Plasmodium falciparum can evade detection by peripheral smear in women with placental malaria (PM). We evaluated host biomarkers as potential indicators of occult PM infections.

Methods and Findings

Using a case-control design, we evaluated the ability of biomarkers to identify PM in the absence of circulating peripheral parasites (n = 24) compared to placental smear-negative controls (n = 326). We measured levels of biomarkers (C3a, C5a, CRP, angiopoietin-1, angiopoietin-2, sTie-2, sEndoglin, VEGF, sFlt-1, tissue factor, and leptin) in maternal peripheral plasma at delivery. Using ROC curve analysis, we assessed the ability of clinical parameters and biomarkers to accurately detect PM infections identified by placental smear. We show that decreases in sFlt-1 and leptin and increases in CRP were associated with occult PM infections (p<0.01) and correlated with placental parasitaemia (p<0.01). Individually, all markers had moderate ability to diagnose occult PM infections with areas under the ROC between 0.62 and 0.72. In order to improve diagnostic performance, we generated simple scoring systems to identify PM infections using either a clinical score (0–2), a biomarker score (0–3) or a clinical plus biomarker score (0–5). The combinatorial model that incorporated both clinical parameters and biomarkers had an area under curve (AUC) of 0.85 (95% CI, 0.81-0.89), which was significantly better at identifying occult PM infections than the clinical score alone (p = 0.001).

Conclusion

These data suggest that host biomarkers in the maternal peripheral blood may improve the detection of PM in the absence of peripheral parasitaemia.     

Estimation of the number and demographics of companion dogs in the UK

Background

The grey partridge is an important game bird in Europe that has declined considerably over the last decades. The production and release of farm-bred birds can be threatened by infectious agents. The objective of this study was to describe the outbreak, pathology, and blood and tissue biochemical responses in a flock of grey partridges naturally infected with Mycoplasma gallisepticum.

Results

Morbidity and mortality rates were 100% and 60%, respectively. Necropsy revealed an accumulation of caseous exudate within the infraorbital sinuses, tracheitis, pneumonia and airsacculitis. There were significant increases in activities of lactate dehydrogenase, creatine kinase and amylase, and levels of total protein and glucose in Mycoplasma-infected birds when compared to control. Catalase showed significantly lower activity in the heart, lungs, liver and gonads of Mycoplasma-infected birds. Glutathione-S-transferase activity was elevated in the eye and the associated infraorbital sinus and kidneys, and decreased in the liver. Decreased levels of reduced glutathione were found in the heart, kidneys, liver and gonads. The activity of glutathione reductase was lower only in the lungs. Compared to healthy birds, mycoplasmosis in the grey partridge caused significant differences in the level of lipid peroxidation in lungs and plasma (p < 0.05), while the ferric reducing antioxidant power was lower in the heart and kidneys (p < 0.01). Significant correlations among responses of the antioxidant parameters were found namely in the heart, lungs, spleen, liver and plasma. There were also numerous significant inter-tissue correlations of all the studied antioxidant parameters.

Conclusions

The present study demonstrates the high susceptibility of grey partridges to natural infection by M. gallisepticum, the severity of the disease based on histopathology, and the modulation of blood chemical profiles and oxidative stress-associated parameters in the avian hosts, thus enhancing the understanding of the pathogenesis of mycoplasmosis in birds. Moreover, the reported reference values can be useful for the evaluation of the state of health in grey partridges.     

8-OxoA inhibits the incision of an AP site by the DNA glycosylases Fpg, Nth and the AP endonuclease HAP1

Ionizing radiation induces clustered DNA damage sites, whereby two or more individual DNA lesions are formed within one or two helical turns of DNA by a single radiation track. A subset of DNA clustered damage sites exist in which the lesions are located in tandem on the same DNA strand. Recent studies have established that two closely opposed lesions impair the repair machinery of the cell, but few studies have investigated the processing of tandem lesions. In this study, synthetic double-stranded oligonucleotides were synthesized to contain 8-oxoA and an AP site in tandem, separated by up to four bases in either a 5' or 3' orientation. The influence 8-oxoA has on the incision of the AP site by the E. coli glycosylases Fpg and Nth protein and the human AP endonuclease HAP1 was assessed. 8-OxoA has little or no effect on the efficiency of incision of the AP site by Nth protein; however, the efficiency of incision of the AP site by Fpg protein is reduced in the presence of 8-oxoA even up to a four-base separation in both the 5' and 3' orientations. 8-OxoA influences the efficiency of HAP1 incision of the AP site only when it is 3' to the AP site and separated by up to two bases. This study demonstrates that the initial stages of base excision repair can be impaired by the presence of a second base lesion in proximity to an AP site on the same DNA strand. This impairment could have biological consequences, such as mutation induction, if the AP site is present at replication.     

Faster Rubisco is the key to superior nitrogen-use efficiency in NADP-malic enzyme relative to NAD-malic enzyme C4 grasses

In 27 C4 grasses grown under adequate or deficient nitrogen (N) supplies, N-use efficiency at the photosynthetic (assimilation rate per unit leaf N) and whole-plant (dry mass per total leaf N) level was greater in NADP-malic enzyme (ME) than NAD-ME species. This was due to lower N content in NADP-ME than NAD-ME leaves because neither assimilation rates nor plant dry mass differed significantly between the two C4 subtypes. Relative to NAD-ME, NADP-ME leaves had greater in vivo (assimilation rate per Rubisco catalytic sites) and in vitro Rubisco turnover rates (k(cat); 3.8 versus 5.7 s(-1) at 25 degrees C). The two parameters were linearly related. In 2 NAD-ME (Panicum miliaceum and Panicum coloratum) and 2 NADP-ME (Sorghum bicolor and Cenchrus ciliaris) grasses, 30% of leaf N was allocated to thylakoids and 5% to 9% to amino acids and nitrate. Soluble protein represented a smaller fraction of leaf N in NADP-ME (41%) than in NAD-ME (53%) leaves, of which Rubisco accounted for one-seventh. Soluble protein averaged 7 and 10 g (mmol chlorophyll)(-1) in NADP-ME and NAD-ME leaves, respectively. The majority (65%) of leaf N and chlorophyll was found in the mesophyll of NADP-ME and bundle sheath of NAD-ME leaves. The mesophyll-bundle sheath distribution of functional thylakoid complexes (photosystems I and II and cytochrome f) varied among species, with a tendency to be mostly located in the mesophyll. In conclusion, superior N-use efficiency of NADP-ME relative to NAD-ME grasses was achieved with less leaf N, soluble protein, and Rubisco having a faster k(cat).     

Development of a microplate-based, electrophoretic fluorescent protein kinase a assay: comparison with filter-binding and fluorescence polarization assay formats

A microplate-based electrophoretic assay has been developed for the serine/threonine kinase protein kinase A (PKA). The ElectroCapture PKA assay developed uses a positively charged, lissamine-rhodamine-labeled kemptide peptide substrate for the kinase reaction and Nanogen's ElectroCapture HTS Workstation and 384-well laminated membrane plates to electrophoretically separate the negatively charged phosphorylated peptide product from the kinase reaction mix. After the electrophoretic separation, the amount of rhodamine-labeled phosphopeptide product was quantified using a Tecan Ultra384 fluorescence reader. The ElectroCapture PKA assay was validated with both known PKA inhibitors and library compounds. The pK(iapp) results obtained in the ElectroCapture PKA assay were comparable to those generated with current radioactive filter-binding assay and antibody-based competitive fluorescence polarization PKA assay formats.     

Mutations that cause osteoglophonic dysplasia define novel roles for FGFR1 in bone elongation

Activating mutations in the genes for fibroblast growth factor receptors 1-3 (FGFR1-3) are responsible for a diverse group of skeletal disorders. In general, mutations in FGFR1 and FGFR2 cause the majority of syndromes involving craniosynostosis, whereas the dwarfing syndromes are largely associated with FGFR3 mutations. Osteoglophonic dysplasia (OD) is a "crossover" disorder that has skeletal phenotypes associated with FGFR1, FGFR2, and FGFR3 mutations. Indeed, patients with OD present with craniosynostosis, prominent supraorbital ridge, and depressed nasal bridge, as well as the rhizomelic dwarfism and nonossifying bone lesions that are characteristic of the disorder. We demonstrate here that OD is caused by missense mutations in highly conserved residues comprising the ligand-binding and transmembrane domains of FGFR1, thus defining novel roles for this receptor as a negative regulator of long-bone growth.     

Preferential transmission of paternal alleles at risk genes in attention-deficit/hyperactivity disorder

Family, twin, and adoption studies have demonstrated a significant genetic contribution to the etiology of attention-deficit/hyperactivity disorder (ADHD). Pharmacological, neuroimaging, and animal-model findings suggest imbalances in monoaminergic (dopaminergic, serotonergic, and noradrenergic) neurotransmission in ADHD. We have examined monoaminergic candidate genes for possible genetic association with ADHD in the Irish population, focusing particularly on genes of the dopaminergic and serotonergic systems. We have observed that several of these genes are associated with ADHD, including DAT1, DBH, DRD4, DRD5, and 5HT1B. Here, we present what appears to be a systematic overtransmission of paternal alleles at candidate genes associated with ADHD. For the nine genes included in the analysis, the overall odds ratio for paternal transmission was 2, compared with 1.3 for maternal transmission (paternal vs. maternal chi 2=9.6; P=.0019). Transmission to females, from either parent, was significantly stronger than to males. Possible reasons for this preferential transmission include imprinting and ascertainment bias, although results of further analyses show that the latter is unlikely.     

TLR-induced inflammation in cystic fibrosis and non-cystic fibrosis airway epithelial cells

Cystic fibrosis (CF) is a genetic disease characterized by severe neutrophil-dominated airway inflammation. An important cause of inflammation in CF is Pseudomonas aeruginosa infection. We have evaluated the importance of a number of P. aeruginosa components, namely lipopeptides, LPS, and unmethylated CpG DNA, as proinflammatory stimuli in CF by characterizing the expression and functional activity of their cognate receptors, TLR2/6 or TLR2/1, TLR4, and TLR9, respectively, in a human tracheal epithelial line, CFTE29o(-), which is homozygous for the DeltaF508 CF transmembrane conductance regulator mutation. We also characterized TLR expression and function in a non-CF airway epithelial cell line 16HBE14o(-). Using RT-PCR, we demonstrated TLR mRNA expression. TLR cell surface expression was assessed by fluorescence microscopy. Lipopeptides, LPS, and unmethylated CpG DNA induced IL-8 and IL-6 protein production in a time- and dose-dependent manner. The CF and non-CF cell lines were largely similar in their TLR expression and relative TLR responses. ICAM-1 expression was also up-regulated in CFTE29o(-) cells following stimulation with each agonist. CF bronchoalveolar lavage fluid, which contains LPS, bacterial DNA, and neutrophil elastase (a neutrophil-derived protease that can activate TLR4), up-regulated an NF-kappaB-linked reporter gene and increased IL-8 protein production in CFTE29o(-) cells. This effect was abrogated by expression of dominant-negative versions of MyD88 or Mal, key signal transducers for TLRs, thereby implicating them as potential anti-inflammatory agents for CF.     

Effects of leaf and branch removal on carbon assimilation and stem wood density of Eucalyptus grandis seedlings

The rate of leaf CO₂ assimilation (A _l) and leaf area determine the rate of canopy CO₂ assimilation (A _c) can be thought proportional to assimilate supply for growth and structural requirements of plants. Partitioning of biomass within plants and anatomy of cells within stems can determine how assimilate supply affects both stem growth and wood density. We examined the response of stem growth and wood density to reduced assimilate supply by pruning leaf area. Removing 42% of the leaf area of Eucalyptus grandis Hill ex Maiden seedlings did not stimulate leaf-level photosynthesis (A _l) or stomatal conductance, contrary to some previous studies. Canopy-level photosynthesis (A _c) was reduced by 41% immediately after pruning but due almost solely to continued production of leaves, and was only 21% lower 3 weeks later. Pruning consequently reduced seedling biomass by 24% and stem biomass by 18%. These reductions in biomass were correlated with reduced A _c. Pruning had no effect on stem height or diameter and reduced wood density to 338 kg m⁻³ compared to 366 kg m⁻³ in control seedlings. The lower wood density in pruned seedlings was associated with a 10% reduction in the thickness of fibre cell walls, and as fibre cell diameter was invariant to pruning, this resulted in smaller lumen diameters. These anatomical changes increased the ratio of cross-sectional area of lumen to area cell wall material within the wood. The results suggest changes to wood density following pruning of young eucalypt trees may be independent of tree volume and of longer duration.