Variations in lethal toxin and cholesterol-dependent cytolysin production correspond to differences in cytotoxicity among strains of Clostridium sordellii

Clostridium sordellii is an emerging human pathogen and frequent contaminant of cadaver-derived tissue transplant material. Herein, we provide data suggesting the potential for severe C. sordellii-associated disease may be dictated by whether the specific strain produces lethal toxin (TcsL) or sordellilysin (SDL), a cholesterol-dependent cytolysin. The virulence factor profiles of 14 C. sordellii isolates were determined, and culture supernatant from six of the isolates was found to be cytotoxic to mammalian cells; yet, only one of these strains conferred cytotoxicity via production of TcsL. Cytotoxicity of TcsL- strains correlated with the production of sordellilysin, which was also recognized by an antiperfringolysin O antibody. However, supernatant from TcsL+, SDL- strains demonstrated a lower LD50 relative to TcsL-, SDL+ strains, suggesting the potential for severe C. sordellii-associated disease may be determined by the particular strain colonizing the host.     

Diagnostic Accuracy and Cost-Effectiveness of Alternative Methods for Detection of Soil-Transmitted Helminths in a Post-Treatment Setting in Western Kenya

Objectives

This study evaluates the diagnostic accuracy and cost-effectiveness of the Kato-Katz and Mini-FLOTAC methods for detection of soil-transmitted helminths (STH) in a post-treatment setting in western Kenya. A cost analysis also explores the cost implications of collecting samples during school surveys when compared to household surveys.

Methods

Stool samples were collected from children (n = 652) attending 18 schools in Bungoma County and diagnosed by the Kato-Katz and Mini-FLOTAC coprological methods. Sensitivity and additional diagnostic performance measures were analyzed using Bayesian latent class modeling. Financial and economic costs were calculated for all survey and diagnostic activities, and cost per child tested, cost per case detected and cost per STH infection correctly classified were estimated. A sensitivity analysis was conducted to assess the impact of various survey parameters on cost estimates.

Results

Both diagnostic methods exhibited comparable sensitivity for detection of any STH species over single and consecutive day sampling: 52.0% for single day Kato-Katz; 49.1% for single-day Mini-FLOTAC; 76.9% for consecutive day Kato-Katz; and 74.1% for consecutive day Mini-FLOTAC. Diagnostic performance did not differ significantly between methods for the different STH species. Use of Kato-Katz with school-based sampling was the lowest cost scenario for cost per child tested ($10.14) and cost per case correctly classified ($12.84). Cost per case detected was lowest for Kato-Katz used in community-based sampling ($128.24). Sensitivity analysis revealed the cost of case detection for any STH decreased non-linearly as prevalence rates increased and was influenced by the number of samples collected.

Conclusions

The Kato-Katz method was comparable in diagnostic sensitivity to the Mini-FLOTAC method, but afforded greater cost-effectiveness. Future work is required to evaluate the cost-effectiveness of STH surveillance in different settings.     

Developmental perspectives on personality: implications for ecological and evolutionary studies of individual differences

Developmental processes can have major impacts on the correlations in behaviour across contexts (contextual generality) and across time (temporal consistency) that are the hallmarks of animal personality. Personality can and does change: at any given age or life stage it is contingent upon a wide range of experiential factors that occurred earlier in life, from prior to conception through adulthood. We show how developmental reaction norms that describe the effects of prior experience on a given behaviour can be used to determine whether the effects of a given experience at a given age will affect contextual generality at a later age, and to illustrate how variation within individuals in developmental plasticity leads to variation in contextual generality across individuals as a function of experience. We also show why niche-picking and niche-construction, behavioural processes which allow individuals to affect their own developmental environment, can affect the contextual generality and the temporal consistency of personality. We conclude by discussing how an appreciation of developmental processes can alert behavioural ecologists studying animal personality to critical, untested assumptions that underlie their own research programmes, and outline situations in which a developmental perspective can improve studies of the functional significance and evolution of animal personality.     

Systematic characterization of nuclear proteome during apoptosis: a quantitative proteomic study by differential extraction and stable isotope labeling

Identification and characterization of the nuclear proteome is important for detailed understanding of multiple signaling events in eukaryotic cells. Toward this goal, we extensively characterized the nuclear proteome of human T leukemia cells by sequential extraction of nuclear proteins with different physicochemical properties using three buffer conditions. This large scale proteomic study also tested the feasibility and technical challenges associated with stable isotope labeling by amino acids in cell culture (SILAC) to uncover quantitative changes during apoptosis. Analyzing proteins from three nuclear fractions extracted from naive and apoptotic cells generated 780,530 MS/MS spectra that were used for database searching using the SEQUEST algorithm. This analysis resulted in the identification and quantification of 1,174 putative nuclear proteins. A number of known nuclear proteins involved in apoptosis as well as novel proteins not known to be part of the nuclear apoptotic machinery were identified and quantified. Consistent with SILAC-based quantifications, immunofluorescence staining of nucleus, mitochondria, and some associated proteins from both organelles revealed a dynamic recruitment of mitochondria into nuclear invaginations during apoptosis.     

Moderate folate depletion modulates the expression of selected genes involved in cell cycle, intracellular signaling and folate uptake in human colonic epithelial cell lines

Folate deficiency may affect gene expression by disrupting DNA methylation patterns or by inducing base substitution, DNA breaks, gene deletions and gene amplification. Changes in expression may explain the inverse relationship observed between folate status and risk of colorectal cancer. Three cell lines derived from the normal human colon, HCEC, NCM356 and NCM460, were grown for 32–34 days in media containing 25, 50, 75 or 150 nM folic acid, and the expression of genes involved in cell-cycle checkpoints, intracellular signaling, folate uptake and cell adhesion and migration was determined. Expression of Folate Receptor 1 was increased with decreasing media folate in all cell lines, as was p53, p21, p16 and β-catenin. With decreasing folate, the expression of both E-cadherin and SMAD-4 was decreased in NCM356. APC was elevated in NCM356 but unchanged in the other lines. No changes in global methylation were detected. A significant increase in p53 exon 7–8 strand breaks was observed with decreasing folate in NCM460 cells. The changes observed are consistent with DNA damage-induced activation of cell-cycle checkpoints and cellular adaptation to folate depletion. Folate-depletion-induced changes in the Wnt/APC pathway as well as in genes involved in cell adhesion, migration and invasion may underlie observed relationships between folate status and cancer risk.     

Identification of Free Nitric Oxide Radicals in Rat Bone Marrow: Implications for Progenitor Cell Mobilization in Hypertension

Nitric oxide (NO) has been implicated in matrix metallopeptidase 9 (MMP9)-dependent mobilization of hematopoietic stem and progenitor cells from bone marrow (BM). However, direct measurement of NO in the BM remained elusive due to its low in situ concentration and short lifetime. Using NO spin trapping and electron paramagnetic resonance (EPR) spectroscopy we give the first experimental confirmation of free NO radicals in rodent BM. NO production was quantified and attributed to enzymatic activity of NO synthases (NOS). Although endothelial NOS (eNOS) accounts for most (66%) of basal NO, we identified a significant contribution (23%) from inducible NOS (iNOS). Basal NO levels closely correlate with MMP9 bioavailability in BM of both hypertensive and control rats. Our observations support the hypothesis that inadequate mobilization of BM-derived stem and progenitor cells in hypertension results from impaired NOS/NO/MMP9 signalling in BM, a condition that may be corrected with pharmacological intervention.     

Lipid response patterns in acute phase paediatric <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> malaria

Introduction

Several studies have observed serum lipid changes during malaria infection in humans. All of them were focused at analysis of lipoproteins, not specific lipid molecules. The aim of our study was to identify novel patterns of lipid species in malaria infected patients using lipidomics profiling, to enhance diagnosis of malaria and to evaluate biochemical pathways activated during parasite infection.

Methods

Using a multivariate characterization approach, 60 samples were representatively selected, 20 from each category (mild, severe and controls) of the 690 study participants between age of 0.5–6 years. Lipids from patient’s plasma were extracted with chloroform/methanol mixture and subjected to lipid profiling with application of the LCMS-QTOF method.

Results

We observed a structured plasma lipid response among the malaria-infected patients as compared to healthy controls, demonstrated by higher levels of a majority of plasma lipids with the exception of even-chain length lysophosphatidylcholines and triglycerides with lower mass and higher saturation of the fatty acid chains. An inverse lipid profile relationship was observed when plasma lipids were correlated to parasitaemia.

Conclusions

This study demonstrates how mapping the full physiological lipid response in plasma from malaria-infected individuals can be used to understand biochemical processes during infection. It also gives insights to how the levels of these molecules relate to acute immune responses.