Biomarkers of oxidative stress and its association with the urinary reducing capacity in bus maintenance workers.

BACKGROUND: Exposure to particles (PM) induces adverse health effects (cancer, cardiovascular and pulmonary diseases). A key-role in these adverse effects seems to be played by oxidative stress, which is an excess of reactive oxygen species relative to the amount of reducing species (including antioxidants), the first line of defense against reactive oxygen species. The aim of this study was to document the oxidative stress caused by exposure to respirable particles in vivo, and to test whether exposed workers presented changes in their urinary levels for reducing species.METHODS: Bus depot workers (n = 32) exposed to particles and pollutants (respirable PM4, organic and elemental carbon, particulate metal content, polycyclic aromatic hydrocarbons, NOx, O3) were surveyed over two consecutive days. We collected urine samples before and after each shift, and quantified an oxidative stress biomarker (8-hydroxy-2'-deoxyguanosine), the reducing capacity and a biomarker of PAH exposure (1-hydroxypyrene). We used a linear mixed model to test for associations between the oxidative stress status of the workers and their particle exposure as well as with their urinary level of reducing species.RESULTS: Workers were exposed to low levels of respirable PM4 (range 25-71 μg/m3). However, urinary levels of 8-hydroxy-2'-deoxyguanosine increased significantly within each shift and between both days for non-smokers. The between-day increase was significantly correlated (p < 0.001) with the concentrations of organic carbon, NOx, and the particulate copper content. The within-shift increase in 8OHdG was highly correlated to an increase of the urinary reducing capacity (Spearman ρ = 0.59, p < 0.0001).CONCLUSIONS: These findings confirm that exposure to components associated to respirable particulate matter causes a systemic oxidative stress, as measured with the urinary 8OHdG. The strong association observed between urinary 8OHdG with the reducing capacity is suggestive of protective or other mechanisms, including circadian effects. Additional investigations should be performed to understand these observations.

A new measurement of energy expenditure and physical activity in patients treated by maintenance hemodialysis

Purpose: The accurate estimation of total energy expenditure (TEE) is essential to allow the provision of nutritional requirements in patients treated by maintenance hemodialysis (MHD). The measurement of TEE and resting energy expenditure (REE) by direct or indirect calorimetry and doubly labeled water are complicated, timeconsuming and cumbersome in this population. Recently, a new system called SenseWear® armband (SWA) was developed to assess TEE, physical activity and REE. This device works by measurements of body acceleration in two axes, heat production and steps counts. REE measured by indirect calorimetry and SWA are well correlated. The aim of this study was to determine TEE, physical activity and REE on patients on MHD using this new device. Methods and materials: Daily TEE, REE, step count, activity time, intensity of activity and lying time were determined for 7 consecutive days in unselected stable patients on MHD and sex, age and weightmatched healthy controls (HC). Patients with malnutrition, cancer, use of immunosuppressive drugs, hypoalbumemia <35 g/L and those hospitalized in the last 3 months, were excluded. For MHD patients, separate analyses were conducted in dialysis and non-dialysis days. Relevant parameters known to affect REE, such as BMI, albumin, pre-albumin, hemoglobin, Kt/V, CRP, bicarbonate, PTH, TSH, were recorded. Results: Thirty patients on MHD and 30 HC were included. In MHD patients, there were 20 men and 10 women. Age was 60,13 years ± 14.97 (mean ± SD), BMI was 25.77 kg/m² ± 4.73 and body weight was 74.65 kg ± 16.16. There were no significant differences between the two groups. TEE was lower in MHD patients compared to HC (28.79 ± 5.51 SD versus 32.91 ± 5.75 SD kcal/kg/day; p <0.01). Activity time was significantly lower in patients on MHD (101.3 ± 12.6SD versus 50.7 ± 9.4 SD min; p = 0.0021). Energy expenditure during the time of activity was significantly lower in MHD patients. MHD patients walked 4543 ± 643 SD vs 8537 ± 744 SD steps per day (p <0.0001). Age was negatively correlated with TEE (r = -0.70) and intensity of activity (r = -0.61) in HC, but not in patients on MHD. TEE showed no difference between dialysis and non-dialysis days (29.92 ± 2.03 SD versus 28.44 ± 1.90 SD kcal/kg/day; p = NS), reflecting a lack of difference in activity (number of steps, time of physical activity) and REE. This finding was observed in MHD patients both older and younger than 60 years. However, age stratification appeared to have an influence on TEE, regardless of dialysis day, (29.92 ± 2.07 SD kcal/kg/day for <60 years-old versus 27.41 ± 1.04 SD kcal/kg/day for ≥60 years old), although failing to reach statistical significance. Conclusion: Using SWA, we have shown that stable patients on MHD have a lower TEE than matched HC. On average, a TEE of 28.79 kcal/kg/day, partially affected by age, was measured. This finding gives support to the clinical impression that it is difficult and probably unnecessary to provide an energy amount of 30-35 kcal/kg/day, as proposed by international guidelines for this population. In addition, we documented for the first time that MHD patients exert a reduced physical activity as compared to HC. There were surprisingly no differences in TEE, REE and physical activity parameters between dialysis and non-dialysis days. This observation might be due to the fact that patients on MHD produce a physical effort to reach the dialysis centre. Age per se did not influence physical activity in MHD patients, contrary to HC, reflecting the impact of co-morbidities on physical activity in this group of patients.

Social network architecture and the maintenance of deleterious cultural traits.

How have changes in communications technology affected the way that misinformation spreads through a population and persists? To what extent do differences in the architecture of social networks affect the spread of misinformation, relative to the rates and rules by which individuals transmit or eliminate different pieces of information (cultural traits)? Here, we use analytical models and individual-based simulations to study how a 'cultural load' of misinformation can be maintained in a population under a balance between social transmission and selective elimination of cultural traits with low intrinsic value. While considerable research has explored how network architecture affects percolation processes, we find that the relative rates at which individuals transmit or eliminate traits can have much more profound impacts on the cultural load than differences in network architecture. In particular, the cultural load is insensitive to correlations between an individual's network degree and rate of elimination when these quantities vary among individuals. Taken together, these results suggest that changes in communications technology may have influenced cultural evolution more strongly through changes in the amount of information flow, rather than the details of who is connected to whom.

Incidence, complications and risk factors for severe falls in patients on maintenance haemodialysis.

BACKGROUND: Falls have been insufficiently studied in patients on maintenance haemodialysis (MHD). This study assessed the incidence and complications of severe falls and the ability of risk factors, including the Performance-Oriented Mobility Assessment (POMA) test, to predict them in this population. METHODS: All patients on MHD from our centre were asked to participate in this survey. POMA test and a record of risk factors for falls were obtained at baseline. Severe falls, as defined by an admission in an emergency ward, were documented prospectively. RESULTS: Eighty-four patients (median age 69.5 years, minimum 26 years, maximum 85 years) were enrolled. Predialytic POMA scores were low (median 20, minimum 5, maximum 26). After a mean follow-up of 20.6 months (142.2 patient-years), 31 severe falls were recorded in 24 patients (28.6%; incidence 0.22 per patient-year) and complicated by fractures in 54.8% of severe falls. In univariate analysis, age, a past history of falls, malnutrition, depression, but not POMA score, were associated with severe falls. A POMA score of >21 had a negative predictive value of 82%. CONCLUSIONS: Severe falls were common in MHD patients in this study and resulted in fractures in >50% of the cases. They were associated with ageing, a past history of falls, malnutrition and depression. Although there was a trend towards a lower POMA score in fallers as compared to non-fallers, the POMA score was not an independent predictor of severe falls in this study. These data may help to stratify the patient's risk of falling in order to target programmes to prevent falls in this population.

Strategies for preventing late-onset cytomegalovirus disease in organ transplant recipients.

Objective: The incidence of late-onset cytomegalovirus disease (i.e. disease appearing after discontinuation of antiviral prophylaxis) in solid-organ transplant recipients remains excessively high. This review will focus on describing the several strategies that could potentially reduce the incidence of late-onset cytomegalovirus disease. Methods: We reviewed the literature and presented our own clinical experience in the field. Results: The incidence of late-onset cytomegalovirus disease in recent trials can be as high as 36% in high-risk patients (donor positive/recipient negative for cytomegalovirus). The extension of antiviral prophylaxis to six months has recently proven in a prospective randomized controlled trial to be effective for reducing late-onset cytomegalovirus disease. The monitoring of cytomegalovirus viral load by PCR after the discontinuation of prophylaxis seems to be of moderate usefulness in low/intermediate-risk patients. The use of low-dose valganciclovir could reduce drug toxicity and costs while maintaining similar efficacy, but further studies are needed. A potentially interesting approach to predict the individual risk for development of cytomegalovirus disease appears to be the assessment of specific cell-mediated immune response. If cell-mediated immunity assays become widely available in transplant centers in the future, these assays may possibly be used to tailor the cytomegalovirus preventive strategy on an individual basis. Finally, recent prospective trials have evaluated novel cytomegalovirus vaccines that merit further evaluation in the transplant setting, although currently there is no cytomegalovirus vaccine that has been approved for routine clinical use. Conclusions: Several studies have recently evaluated novel strategies to reduce the incidence of late-onset cytomegalovirus disease. It is therefore expected that this improvement in preventive strategies will allow to further reduce the negative effects of cytomegalovirus disease after transplantation.

Calpain 3, the "gatekeeper" of proper sarcomere assembly, turnover and maintenance.

Calpain 3 is a member of the calpain family of calcium-dependent intracellular proteases. Thirteen years ago it was discovered that mutations in calpain 3 (CAPN3) result in an autosomal recessive and progressive form of limb girdle muscular dystrophy called limb girdle muscular dystrophy type 2A. While calpain 3 mRNA is expressed at high levels in muscle and appears to have some role in developmental processes, muscles of patients and mice lacking calpain 3 still form apparently normal muscle during prenatal development; thus, a functional calpain 3 protease is not mandatory for muscle to form in vivo but it is a pre-requisite for muscle to remain healthy. Despite intensive research in this field, the physiological substrates of the calpain 3 protein (hereafter referred to as CAPN3) and its alternatively spliced isoforms remain elusive. The existence of these multiple isoforms complicates the search for the physiological functions of CAPN3 and its pathophysiological role. In this review, we summarize the genetic and biochemical evidence that point to loss of function of the full-length isoform of CAPN3, also known as p94, as the pathogenic isoform. We also argue that its natural substrates must reside in its proximity within the sarcomere where it is stored in an inactive state anchored to titin. We further propose that CAPN3 has many attributes that make it ideally suited as a sensor of sarcomeric integrity and function, involved in its repair and maintenance. Loss of these CAPN3-mediated activities can explain the "progressive" development of muscular dystrophy.

Analysis of the Cytoprotective Role of α-Crystallins in Cell Survival and Implication of the αA-Crystallin C-Terminal Extension Domain in Preventing Bax-Induced Apoptosis.

α-Crystallins, initially described as the major structural proteins of the lens, belong to the small heat shock protein family. Apart from their function as chaperones, α-crystallins are involved in the regulation of intracellular apoptotic signals. αA- and αB-crystallins have been shown to interfere with the mitochondrial apoptotic pathway triggering Bax pro-apoptotic activity and downstream activation of effector caspases. Differential regulation of α-crystallins has been observed in several eye diseases such as age-related macular degeneration and stress-induced and inherited retinal degenerations. Although the function of α-crystallins in healthy and diseased retina remains poorly understood, their altered expression in pathological conditions argue in favor of a role in cellular defensive response. In the Rpe65(-/-) mouse model of Leber's congenital amaurosis, we previously observed decreased expression of αA- and αB-crystallins during disease progression, which was correlated with Bax pro-death activity and photoreceptor apoptosis. In the present study, we demonstrated that α-crystallins interacted with pro-apoptotic Bax and displayed cytoprotective action against Bax-triggered apoptosis, as assessed by TUNEL and caspase assays. We further observed in staurosporine-treated photoreceptor-like 661W cells stably overexpressing αA- or αB-crystallin that Bax-dependent apoptosis and caspase activation were inhibited. Finally, we reported that the C-terminal extension domain of αA-crystallin was sufficient to provide protection against Bax-triggered apoptosis. Altogether, these data suggest that α-crystallins interfere with Bax-induced apoptosis in several cell types, including the cone-derived 661W cells. They further suggest that αA-crystallin-derived peptides might be sufficient to promote cytoprotective action in response to apoptotic cell death.

Calpain 3, the "gatekeeper" of proper sarcomere assembly, turnover and maintenance.

Calpain 3 is a member of the calpain family of calcium-dependent intracellular proteases. Thirteen years ago it was discovered that mutations in calpain 3 (CAPN3) result in an autosomal recessive and progressive form of limb girdle muscular dystrophy called limb girdle muscular dystrophy type 2A. While calpain 3 mRNA is expressed at high levels in muscle and appears to have some role in developmental processes, muscles of patients and mice lacking calpain 3 still form apparently normal muscle during prenatal development; thus, a functional calpain 3 protease is not mandatory for muscle to form in vivo but it is a pre-requisite for muscle to remain healthy. Despite intensive research in this field, the physiological substrates of the calpain 3 protein (hereafter referred to as CAPN3) and its alternatively spliced isoforms remain elusive. The existence of these multiple isoforms complicates the search for the physiological functions of CAPN3 and its pathophysiological role. In this review, we summarize the genetic and biochemical evidence that point to loss of function of the full-length isoform of CAPN3, also known as p94, as the pathogenic isoform. We also argue that its natural substrates must reside in its proximity within the sarcomere where it is stored in an inactive state anchored to titin. We further propose that CAPN3 has many attributes that make it ideally suited as a sensor of sarcomeric integrity and function, involved in its repair and maintenance. Loss of these CAPN3-mediated activities can explain the "progressive" development of muscular dystrophy.

Motility tests for drugs preventing PolyQ aggregation in recombinant Caenorhabditis elegans.

The pathological formation of proteinaceous aggregates that accumulate into the brain cells of patients are hallmarks of neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis and the heterogeneous group of polyglutamine (polyQ) diseases. In the polyQ diseases, the most upstream events of the pathogenic cascade are the misfolding and aggregation of proteins, such as huntingtin in Huntington's disease, that contain expanded stretch of glutamine residues above 35--‐40 repeats. This expanded polyQ stretch triggers the misfolding and aggregation of cytotoxic polyQ proteins in the neurons that cause cell death through different processes, like apoptosis, excessive inflammation, formation of free radicals, eventually leading to neuronal loss and neurodegeneration. This study focuses on the cellular network of chaperone proteins that can prevent protein aggregation by binding misfolding intermediates and may, as in the case of HSP70, actively unfold misfolded proteins into refoldable non--‐toxic ones (Hinault et al., 2010; Sharma et al., 2011). The chaperones can also collaborate with the proteasome to convert stable harmful proteins into harmless amino acids. Thus, the chaperone proteins that are the most important cellular factors of prevention and curing of protein misfolding, are negatively affected by aging (Morley et al., 2002) and fail to act properly in the neurons of aged persons, which eventually may lead to neurodegenerative pathologies. The general aim of this research was to identify least toxic drugs that can upregulate the expression of chaperone genes in cells suffering from polyQ--‐ mediated protein aggregation and degeneration. The specific aim of this study was to observe the effect of ten drugs on polyQ aggregation in a recombinant nematode Caenorhabditis elegans expressing a chimeric protein containing a sequence of 35 glutamines (Q35) fused to the green fluorescent protein in muscle cells, which causes an age--‐ and temperature--‐ dependent phenotype of accelerated paralysis. The drugs were selected after having proven their causing the overexpression of chaperone proteins in a previous wide screening of 2000 drugs on the moss plant Physcomitrella patens. The screening that we performed in this study was on these ten drugs. It suggested that piroxicam and anisindione were good reducers of polyglutamine disease mediated paralysis. A hypothesis can be made that they may act as good enhancers of the heat shock response, which causes the overexpression of many HSP chaperones and thus reduce motility impairment of polyQ disease expressing nematodes. Piroxicam was found to have the greatest effect on reducing polyQ35 proteins aggregates mediated paralysis in a dose--‐dependent manner but was also found to either have a toxic effect on wild type C.elegans, either to change its natural motility behavior, eventually reducing its motility in both cases. Chloroform should be preferred over DMSO as a drug solvent as it appears to be less toxic to C.elegans.

Interactions between cancer stem cells and their niche govern metastatic colonization.

Metastatic growth in distant organs is the major cause of cancer mortality. The development of metastasis is a multistage process with several rate-limiting steps. Although dissemination of tumour cells seems to be an early and frequent event, the successful initiation of metastatic growth, a process termed 'metastatic colonization', is inefficient for many cancer types and is accomplished only by a minority of cancer cells that reach distant sites. Prevalent target sites are characteristic of many tumour entities, suggesting that inadequate support by distant tissues contributes to the inefficiency of the metastatic process. Here we show that a small population of cancer stem cells is critical for metastatic colonization, that is, the initial expansion of cancer cells at the secondary site, and that stromal niche signals are crucial to this expansion process. We find that periostin (POSTN), a component of the extracellular matrix, is expressed by fibroblasts in the normal tissue and in the stroma of the primary tumour. Infiltrating tumour cells need to induce stromal POSTN expression in the secondary target organ (in this case lung) to initiate colonization. POSTN is required to allow cancer stem cell maintenance, and blocking its function prevents metastasis. POSTN recruits Wnt ligands and thereby increases Wnt signalling in cancer stem cells. We suggest that the education of stromal cells by infiltrating tumour cells is an important step in metastatic colonization and that preventing de novo niche formation may be a novel strategy for the treatment of metastatic disease.

The evolution, maintenance and adaptive function of genetic colour polymorphism in birds.

The hypothesis that ornaments can honestly signal quality only if their expression is condition-dependent has dominated the study of the evolution and function of colour traits. Much less interest has been devoted to the adaptive function of colour traits for which the expression is not, or is to a low extent, sensitive to body condition and the environment in which individuals live. The aim of the present paper is to review the current theoretical and empirical knowledge of the evolution, maintenance and adaptive function of colour plumage traits for which the expression is mainly under genetic control. The finding that in many bird species the inheritance of colour morphs follows the laws of Mendel indicates that genetic colour polymorphism is frequent. Polymorphism may have evolved or be maintained because each colour morph facilitates the exploitation of alternative ecological niches as suggested by the observation that individuals are not randomly distributed among habitats with respect to coloration. Consistent with the hypothesis that different colour morphs are linked to alternative strategies is the finding that in a majority of species polymorphism is associated with reproductive parameters, and behavioural, life-history and physiological traits. Experimental studies showed that such covariations can have a genetic basis. These observations suggest that colour polymorphism has an adaptive function. Aviary and field experiments demonstrated that colour polymorphism is used as a criterion in mate-choice decisions and dominance interactions confirming the claim that conspecifics assess each other's colour morphs. The factors favouring the evolution and maintenance of genetic variation in coloration are reviewed, but empirical data are virtually lacking to assess their importance. Although current theory predicts that only condition-dependent traits can signal quality, the present review shows that genetically inherited morphs can reveal the same qualities. The study of genetic colour polymorphism will provide important and original insights on the adaptive function of conspicuous traits.