Effect of exogenous circulating anti-bPL antibodies on bovine placental lactogen measurements in foetal samples

Background  

The involvement of placental lactogen (PL) in the regulation of foetal growth has been investigated in different species by in vivo immunomodulation techniques. However, when circulating antibodies are present together with the hormone, the procedure for hormonal measurement becomes considerably complex. The aim of this study was the immunoneutralization of bovine placental lactogen (bPL) concentrations in bovine foetal circulation by direct infusion of rabbit anti-bPL purified immunoglobulins (IgG) via a foetal catheter (in vivo study). The ability of a RIA based on guinea pig anti-bPL antiserum, for the measurement of bPL concentrations in samples containing exogenous rabbit anti-bPL immunoglobulins, was also analyzed in in vitro and in vivo conditions.     

Relationship of aerobic and anaerobic parameters with 400 m front crawl swimming performance

The aims of the present study were to investigate the relationship of aerobic and anaerobic parameters with 400 m performance, and establish which variable better explains long distance performance in swimming. Twenty-two swimmers (19.1±1.5 years, height 173.9±10.0 cm, body mass 71.2±10.2 kg; 76.6±5.3% of 400 m world record) underwent a lactate minimum test to determine lactate minimum speed (LMS) (i.e., aerobic capacity index). Moreover, the swimmers performed a 400 m maximal effort to determine mean speed (S400m), peak oxygen uptake (V.O2PEAK) and total anaerobic contribution (C_ANA). The C_ANA was assumed as the sum of alactic and lactic contributions. Physiological parameters of 400 m were determined using the backward extrapolation technique (V.O2PEAK and alactic contributions of C_ANA) and blood lactate concentration analysis (lactic anaerobic contributions of C_ANA). The Pearson correlation test and backward multiple regression analysis were used to verify the possible correlations between the physiological indices (predictor factors) and S400m (independent variable) (p < 0.05). Values are presented as mean ± standard deviation. Significant correlations were observed between S400m (1.4±0.1 m·s^-1) and LMS (1.3±0.1 m·s^-1; r = 0.80), V.O2PEAK (4.5±3.9 L·min^-1; r = 0.72) and C_ANA (4.7±1.5 L·O₂; r= 0.44). The best model constructed using multiple regression analysis demonstrated that LMS and V.O2PEAK explained 85% of the 400 m performance variance. When backward multiple regression analysis was performed, C_ANA lost significance. Thus, the results demonstrated that both aerobic parameters (capacity and power) can be used to predict 400 m swimming performance.     

Dual strategy for immune defense in the land snail Cornu aspersum (Gastropoda, Pulmonata)

Immune defenses have been shown to be heavily involved in the evolution of physiological trade-offs. In this study, we compared the internal defense systems in two subspecies of the land snail Cornu aspersum that exhibit contrasting life-history strategies. The "fast-living" Cornu aspersum subsp. aspersa is widespread throughout the world, especially in ecosystems disturbed by man, whereas natural populations of the giant Cornu aspersum subsp. maxima, characterized by a longer life span, are present only in north Africa. Snails were experimentally challenged with Escherichia coli; the measurements used to assess their internal defense for cell- and humoral-mediated immune responses were bacterial clearance, hemocyte density, reactive oxygen species (ROS) production, and plasma antibacterial activity. Both subspecies showed a similar ability to clear bacteria from their hemolymph; however, they varied in the robustness of different individual immune components. Cornu aspersum aspersa had higher ROS activity than did C. a. maxima and lower plasma bactericidal activity. These results suggest that ecological factors can sculpt the immune response. One interpretation is that shorter life span selects for immune defenses such as ROS that, although effective, can cause long-term damage. Such different immune patterns obviously entail various costs involved in the strong intraspecific variation of life-history trade-offs we previously observed. We also have to consider that such variation might be related to intraspecific differences in the relative strength of resistance and tolerance mechanisms.     

HIV prevalence and impact on renutrition in children hospitalised for severe malnutrition in Niger: an argument for more systematic screening

Background

In developing countries, malnutrition is a contributing factor in over 50% of child deaths. Mortality rates are higher in underweight children, and HIV-infection is known to increase underweight. Our goals were to evaluate the prevalence of HIV among children hospitalised for severe malnutrition (SM) at the Niamey national hospital (Niger), and to compare renutrition and mortality by HIV-status.

Methods

Retrospective study based on all children <5 years hospitalised for SM between January 1^st 2008 and July 1^st 2009. HIV-prevalence was the ratio of HIV+ children on the number of children tested. Duration of renutrition and mortality were described using survival curves.

Results

During the study period, 477 children were hospitalised for SM. HIV testing was accepted in 470 (98.5%), of which 40 were HIV+ (HIV prevalence (95% confidence interval) of 8.6% (6.2–11.5)). Duration of renutrition was longer in HIV+ than HIV− children (mean: 22 vs. 15 days; p = 0.003). During renutrition, 8 (20%) and 61 (14%) HIV+ and HIV− children died, respectively (p = 0.81).

Conclusion

Around 9% of children hospitalised for severe malnutrition were HIV infected, while in Niger HIV prevalence in adults is estimated at 0.8%. This pleads for wider access to HIV testing in this population.     

A computational investigation of kinetoplastid trans-splicing

Trans-splicing is an unusual process in which two separate RNA strands are spliced together to yield a mature mRNA. We present a novel computational approach which has an overall accuracy of 82% and can predict 92% of known trans-splicing sites. We have applied our method to chromosomes 1 and 3 of Leishmania major, with high-confidence predictions for 85% and 88% of annotated genes respectively. We suggest some extensions of our method to other systems.     

Using co-occurrence network structure to extract synonymous gene and protein names from MEDLINE abstracts

Background  

Text-mining can assist biomedical researchers in reducing information overload by extracting useful knowledge from large collections of text. We developed a novel text-mining method based on analyzing the network structure created by symbol co-occurrences as a way to extend the capabilities of knowledge extraction. The method was applied to the task of automatic gene and protein name synonym extraction.     

The GTPase, CpgA(YloQ), a putative translation factor, is implicated in morphogenesis in Bacillus subtilis

YloQ, from Bacillus subtilis, was identified previously as an essential nucleotide-binding protein of unknown function. YloQ was successfully over-expressed in Escherichia coli in soluble form. The purified protein displayed a low GTPase activity similar to that of other small bacterial GTPases such as Bex/Era. Based on the demonstrated GTPase activity and the unusual order of the yloQ G motifs, we now designate this protein as CpgA (circularly permuted GTPase). An unexpected property of this low abundance GTPase was the demonstration, using gel filtration and ultracentrifugation analysis, that the protein formed stable dimers, dependent upon the concentration of YloQ(CpgA), but independent of GTP. In order to investigate function, cpgA was placed under the control of the pspac promotor in the B. subtilis chromosome. When grown in E or Spizizen medium in the absence of IPTG, the rate of growth was significantly reduced. A large proportion of the cells exhibited a markedly perturbed morphology, with the formation of swollen, bent or ‘curly’ shapes. To confirm that this was specifically due to depleted CpgA a plasmid-borne cpgA under pxyl control was introduced. This restored normal cell shape and growth rate, even in the absence of IPTG, provided xylose was present. The crystal structure of CpgA(YloQ) suggests a role as a translation initiation factor and we discuss the possibility that CpgA is involved in the translation of a subset of proteins, including some required for shape maintenance. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Ubiquitin crosstalk connecting cellular processes

Cullin 4 (Cul4), a member of the evolutionally conserved cullin protein family, serves as a scaffold to assemble multisubunit ubiquitin E3 ligase complexes. Cul4 interacts with the Ring finger-containing protein ROC1 through its C-terminal cullin domain and with substrate recruiting subunit(s) through its N-terminus. Previous studies have demonstrated that Cul4 E3 ligase ubiquitylates key regulators in cell cycle control and mediates their degradation through the proteasomal pathway, thus contributing to genome stability. Recent studies from several groups have revealed that Cul4 E3 ligase can target histones for ubiquitylation, and importantly, ubiquitylation of histones may facilitate the cellular response to DNA damage. Therefore, histone ubiquitylation by Cul4 E3 ligase constitutes a novel mechanism through which Cul4 regulates chromatin function and maintains genomic integrity. We outline these studies and suggest that histone ubiquitylation might play important roles in Cul4-regualted chromatin function including the cellular response to DNA damage and heterochromatin gene silencing.     

Tyrosine-specific MAPK phosphatases and the control of ERK signaling in PC12 cells

Background

Spatio-temporal control of extracellular signal-regulated kinase (ERK) activity, a critical determinant of the cell's response to growth factors, requires timely dephosphorylation of its regulatory tyrosine and/or threonine residue by MAPK phosphatases. We studied the physiological role of kinase interaction motif (KIM)-containing protein tyrosine phosphatases (PTPs) in the control of EGF- and NGF-induced ERK activity in neuroendocrine PC12 cells.

Results

We found a single KIM-containing PTP to be endogenously expressed in rat PC12 cells: the transmembrane PTPRR isoform termed PCPTP1. Protein knock-down of PCPTP1, or fourfold overexpression of its mouse orthologue, PTPBR7, left EGF- and NGF-induced ERK1/2 activity in PC12 cells unaltered. Ectopic expression of cytosolic PTPRR isoforms, however, resulted in reduced EGF-induced ERK1/2 activity, an effect that was dependent on the phosphatase activity and the KIM-domain of these PTPs.

Conclusion

The finding that robust changes in tyrosine-specific MAPK phosphatase expression levels have minor effects on temporal ERK1/2 activity control in PC12 cells suggests that dual-specificity MAPK phosphatases may act as major regulators of growth factor-induced ERK1/2 signaling in these cells.     

Sensitivity of methods for estimating breeding values using genetic markers to the number of QTL and distribution of QTL variance

The objective of this simulation study was to compare the effect of the number of QTL and distribution of QTL variance on the accuracy of breeding values estimated with genomewide markers (MEBV). Three distinct methods were used to calculate MEBV: a Bayesian Method (BM), Least Angle Regression (LARS) and Partial Least Square Regression (PLSR). The accuracy of MEBV calculated with BM and LARS decreased when the number of simulated QTL increased. The accuracy decreased more when QTL had different variance values than when all QTL had an equal variance. The accuracy of MEBV calculated with PLSR was affected neither by the number of QTL nor by the distribution of QTL variance. Additional simulations and analyses showed that these conclusions were not affected by the number of individuals in the training population, by the number of markers and by the heritability of the trait. Results of this study show that the effect of the number of QTL and distribution of QTL variance on the accuracy of MEBV depends on the method that is used to calculate MEBV.