Oxidative stress implication in a new ex-vivo cardiac concordant xenotransplantation model

Xenotransplantation (XT) reveals a growing interest for the treatment of cardiomyopathy. The major barrier is an acute vascular rejection due to an acute humoral rejection. This pathogenesis is a difficult issue and in order to elaborate means for its prevention, we analysed the implication of oxidative stress (OS) on hearts from mini-pigs followed by reperfusion with either autologous or human blood in an attempt to simulate xenotransplantation. About 14 hearts were studied after a Langendorff blood reperfusion: allografts with autologous blood (n = 7) or xenografts with human blood (n = 7). Blood samples were drawn from the coronary sinus to assess ischemia and OS. In xenografts, arrhythmias occurred more frequently (p < 0.01, left ventricular systolic pressure decreased more significantly (p < 0.05), thiobarbituric acid-reactive substances concentrations increased at 30 min (0.7 +/- 0.1 vs. 2.4 +/- 0.3 mmol/l; p < 0.05) while vitamin A levels decreased (p < 0.05). XT was associated with a significant increase in ischemic injury and OS production. OS might play an eminent role in hyperacute humoral rejection.     

Introducing Acacia mangium trees in Eucalyptus grandis plantations: consequences for soil organic matter stocks and nitrogen mineralization

Background and aims

Eucalyptus plantations cover 20 million hectares on highly weathered soils. Large amounts of nitrogen (N) exported during harvesting lead to concerns about their sustainability. Our goal was to assess the potential of introducing A. mangium trees in highly productive Eucalyptus plantations to enhance soil organic matter stocks and N availability.

Methods

A randomized block design was set up in a Brazilian Ferralsol soil to assess the effects of mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and mixed plantations (50A:50E) on soil organic matter stocks and net N mineralization.

Results

A 6-year rotation of mono-specific A. mangium plantations led to carbon (C) and N stocks in the forest floor that were 44% lower and 86% higher than in pure E. grandis stands, respectively. Carbon and N stocks were not significantly different between the three treatments in the 0–15?cm soil layer. Field incubations conducted every 4?weeks for the two last years of the rotation estimated net soil N mineralization in 100A and 100E at 124 and 64?kg?ha^?1?yr^?1, respectively. Nitrogen inputs to soil with litterfall were of the same order as net N mineralization.

Conclusions

Acacia mangium trees largely increased the turnover rate of N in the topsoil. Introducing A. mangium trees might improve mineral N availability in soils where commercial Eucalyptus plantations have been managed for a long time.     

Insight into planar cell polarity

Planar cell polarity or PCP refers to a uniform cellular organization within the plan, typically orthogonal to the apico-basal polarity axis. As such, PCP provides directional cues that control and coordinate the integration of cells in tissues to build a living organism. Although dysfunctions of this fundamental cellular process have been convincingly linked to the etiology of various pathologies such as cancer and developmental defects, the molecular mechanisms governing its establishment and maintenance remain poorly understood. Here, we review some aspects of invertebrate and vertebrate PCPs, highlighting similarities and differences, and discuss the prevalence of the non-canonical Wnt signaling as a central PCP pathway, as well as recent findings on the importance of cell contractility and cilia as promising avenues of investigation.     

X-ray structures of ferritins and related proteins

Ferritins are members of a much larger superfamily of proteins, which are characterised by a structural motif consisting of a bundle of four parallel and anti-parallel α helices. The ferritin superfamily itself is widely distributed across all three living kingdoms, in both aerobic and anaerobic organisms, and a considerable number of X-ray structures are available, some at extremely high resolution. We describe first of all the subunit structure of mammalian H and L chain ferritins and then discuss intersubunit interactions in the 24-subunit quaternary structure of these ferritins. Bacteria contain two types of ferritins, FTNs, which like mammalian ferritins do not contain haem, and the haem-containing BFRs. The characteristic carboxylate-bridged di-iron ferroxidase sites of H chain ferritins, FTNs and BFRs are compared, as are the potential entry sites for iron and the ‘nucleation’ site of L chain ferritins. Finally we discuss the three-dimensional structures of the 12-subunit bacterial Dps (DNA-binding protein from starved cells) proteins as well as their intersubunit di-iron ferroxidase site.     

Endoglin (CD105) expression is regulated by the liver X receptor alpha (NR1H3) in human trophoblast cell line JAR

Human implantation involves invasion of the uterine wall and remodeling of uterine arteries by extravillous cytotrophoblasts. Defects in these early steps of placental development lead to poor placentation and are often associated with preeclampsia, a frequent complication of human pregnancy. One of the complex mechanisms controlling trophoblast invasion involves the activation of the liver X receptor beta (or NR1H2, more commonly known as LXRbeta) by oxysterols known as potent LXR activators. This activation of LXRbeta leads to a decrease of trophoblast invasion. The identification of new target genes of LXR in the placenta could aid in the understanding of their physiological roles in trophoblast invasion. In the present study, we show that the endoglin (ENG) gene is a direct target of the liver X receptor alpha (NR1H3, also known as LXRalpha). ENG, whose gene is highly expressed in syncytiotrophoblasts, is part of the transforming growth factor (TGF) receptor complex that binds several members of the TGFbeta superfamily. In the human placenta, ENG has been shown to be involved in the inhibition of trophoblast invasion. Treatment of human choriocarcinoma JAR cells with T0901317, a synthetic LXR-selective agonist, leads to a significant increase in ENG mRNA and protein levels. Using transfection and electrophoretic mobility shift assays, we demonstrate that LXR (as a heterodimer with the retinoid X receptor) is able to bind the ENG promoter on an LXR response element and mediates the activation of ENG gene expression by LXRalpha in JAR cells. This study suggests a novel mechanism by which LXR may regulate trophoblast invasion in pathological pregnancy such as preeclampsia.     

Is Clinical Practice Concordant with the Changes in Guidelines for Antiretroviral Therapy Initiation during Primary and Chronic HIV-1 Infection? The ANRS PRIMO and COPANA Cohorts

Objective

Guidelines for initiating HIV treatment are regularly revised. We explored how physicians in France have applied these evolving guidelines for ART initiation over the last decade in two different situations: chronic (CHI) and primary HIV-1 infection (PHI), since specific recommendations for PHI are also provided in France.

Methods

Data came from the ANRS PRIMO (1267 patients enrolled during PHI in 1996–2010) and COPANA (800 subjects enrolled at HIV diagnosis in 2004–2008) cohorts. We defined as guidelines-inconsistent during PHI and CHI, patients meeting criteria for ART initiation and not treated in the following month and during the next 6 months, respectively.

Results

ART initiation during PHI dramatically decreased from 91% of patients in 1996–99 to 22% in 2007 and increased to 60% in 2010, following changes in recommendations. In 2007, however, after the CD4 count threshold was raised to 350 cells/mm³ in 2006, only 55% of the patients with CD4≤350 were treated and 66% in 2008. During CHI, ART was more frequently initiated in patients who met the criteria at entry (96%) than during follow-up: 83% when recommendation to treat was 200 and 73% when it was 350 cells/mm³. Independent risk factors for not being treated during CHI despite meeting the criteria were lower viral load, lower educational level, and poorer living conditions.

Conclusion

HIV ART initiation guidelines are largely followed by practitioners in France. What can still be improved, however, is time to treat when CD4 cell counts reach the threshold to treat. Risk factors for lack of timely treatment highlight the need to understand better how patients’ living conditions and physicians’ perceptions influence the decision to initiate treatment.     

Effect of a supplement rich in linolenic acid added to the diet of post partum dairy cows on ovarian follicle growth, and milk and plasma fatty acid compositions

The objective of this study was to determine the effect of a linseed supplement on follicle growth, progesterone concentrations and milk and plasma fatty acids in dairy cows post partum. Sixteen Holstein cows were given a basal total mixed diet plus one of two supplements: control (C; extruded soybeans; n = 8) or linseed (L; extruded linseeds; n = 8). One month after calving oestrous cycles were synchronised (PRID). Follicle growth and milk progesterone concentrations were measured every 2 d over the induced oestrous cycle. Milk production characteristics were unaffected by treatment. The L cows lost significantly more BCS than the C cows (P < 0.01). Plasma insulin, glucose and urea were unaffected by the treatment. Plasma NEFA tended to be affected by the treatment (L > C, P = 0.08). The proportions of 18:3n-3 in milk and plasma were increased by L compared to C (P < 0.001 and P < 0.01, respectively). There was an effect of dietary supplement on the numbers of small follicles (L < C, P < 0.05). Milk progesterone was unaffected by treatment. In conclusion, the increased supply of 18:3n-3 to the cows had only a modest effect on follicle populations and corpus luteum activity was unchanged.     

Galactokinase Mutants of Chinese Hamster Somatic Cells Resistant to 2-Deoxygalactose

The growth of Chinese hamster somatic cells was inhibited by 0.2 mg/cc of 2-deoxygalactose. Mutants partially or fully resistant to 2-deoxygalactose were isolated in a single-step or two-step selection. Some of them did not grow as well as the wild type; one of them which lacked galactokinase(EC.2.7.1.6) activity did not grow at all in galactose medium. The galactokinase kinetic properties (Vmax & kmax of the other mutants and of the wild type were different. Therefore resistance resulted either from the possible absence of galactokinase synthesis or from a structural mutation, possible a missence mutation, in the galactokinase gene.- A simple diagnostic test for juvenile cataract is proposed.     

ERK 1/2- and JNKs-dependent synthesis of interleukins 6 and 8 by fibroblast-like synoviocytes stimulated with protein I/II,a modulin from oral streptococci,requires focal adhesion kinase

Protein I/II, a pathogen-associated molecular pattern from oral streptococci, is a potent inducer of interleukin-6 (IL-6) and IL-8 synthesis and release from fibroblast-like synoviocytes (FLSs), cells that are critically involved in joint inflammation. This synthesis implicates ERK 1/2 and JNKs as well as AP-1-binding activity and nuclear translocation of NF-kappaB. The mechanisms by which protein I/II activates MAPKs remain, however, elusive. Because focal adhesion kinase (FAK) was proposed to play a role in signaling to MAPKs, we examined its ability to contribute to the MAPKs-dependent synthesis of IL-6 and IL-8 in response to protein I/II. We used FAK-/- fibroblasts as well as FAK+/+ fibroblasts and FLSs transfected with FRNK, a dominant negative form of FAK. The results demonstrate that IL-6 and IL-8 release in response to protein I/II was strongly inhibited in both protein I/II-stimulated FAK-/- and FRNK-transfected cells. Cytochalasin D, which inhibits protein I/II-induced phosphorylation of FAK (Tyr-397), had no effect either on activation of ERK 1/2 and JNKs or on IL-6 and IL-8 release. Taken together, these results indicate that IL-6 and IL-8 release by protein I/II-activated FLSs is regulated by FAK independently of Tyr-397 phosphorylation.