Regulation of K-Cl cotransport during reticulocyte maturation and erythrocyte aging in normal and sickle erythrocytes

The age/density-dependent decrease in K-Cl cotransport (KCC), PP1 and PP2A activities in normal and sickle human erythrocytes, and the effect of urea, a known KCC activator, were studied using discontinuous, isotonic gradients. In normal erythrocytes, the densest fraction (d 33.4 g/dl) has only about 5% of the KCC and 4% of the membrane (mb)-PP1 activities of the least-dense fraction (d 24.7 g/dl). In sickle and normal erythrocytes, density-dependent decreases for mb-PP1 activity were similar (d_50% 28.1 ± 0.4 vs. 27.2 ± 0.2 g/dl, respectively), whereas those for KCC activity were not (d_50% 31.4 ± 0.9 vs. 26.8 ± 0.3 g/dl, respectively, P = 0.004). Excluding the 10% least-dense cells, a very tight correlation exists between KCC and mb-PP1 activities in normal (r² = 0.995) and sickle erythrocytes (r² = 0.93), but at comparable mb-PP1 activities, KCC activity is higher in sickle erythrocytes, suggesting a defective, mb-PP1-independent KCC regulation. In normal, least-dense but not in densest cells, urea stimulates KCC (two- to fourfold) and moderately increases mb-PP1 (20–40%). Thus mb-PP1 appears to mediate part of urea-stimulated KCC activity. phosphorylation; protein phosphatase; urea; cell size; density     

A proposed sequence of events for cadmium-induced mitochondrial impairment

Cadmium is a very important environmental toxicant, the cytotoxicity mechanism of which is likely to involve mitochondria as a target. In the present study we addressed the cause/effect relationship between the multiple cadmium-induced responses involving the mitochondrial energetic and oxidative status. Assays were performed with succinate-energized rat liver mitochondria incubated with 5 microM CdCl(2) for 0-25 min, in the absence or presence, respectively, of N-ethylmaleimide (NEM), butylhydroxytoluene (BHT), ruthenium red (RR), and cyclosporine A+ADP. A sequence of events accounting for cadmium-induced mitochondrial impairment is proposed, beginning with an apparent interaction of Cd(2+) with specific protein thiols in the mitochondrial membrane, which stimulates the cation's uptake via the Ca(2+) uniporter, and is followed by the onset of mitochondrial permeability transition (MPT); both effects dissipate the transmembrane electrical potential (Deltapsi), causing uncoupling, followed by an early depression of mitochondrial ATP levels. The respiratory chain subsequently undergoes inhibition, generating reactive oxygen species which together with iron mobilized by the cation, cause late, gradual mitochondrial membrane lipid peroxidation.     

The Role of School Environment in Physical Activity among Brazilian Adolescents

Objective

To analyze the association of physical activity facilities and extracurricular sports activities in schools with physical activity among adolescents.

Methodology/Principal Findings

We used data collected for the National Survey of School Health in 2012. The national representative sample comprised 109,104 Brazilian students from 2,842 schools. We calculated the prevalence of participation in physical education classes, leisure-time physical activity, and total physical activity level. We also evaluated the following physical activity facilities: sports courts, running/athletics tracks, schoolyard with teacher-directed physical activities, swimming pools, locker rooms; and the offer of extracurricular sports activities. Schools with at least one physical activity facility had increased odds of participation in physical education (OR 1.59; 95% CI 1.20 to 2.10). However, in order to increase leisure-time physical activity (OR1.14; 95% CI 1.03 to 1.26) and total physical activity level (OR 1.15; 95% CI 1.06 to 1.24) at least four and two facilities, respectively, were necessary. Extracurricular sports activities in schools were positively associated with leisure-time physical activity and physical activity level. The number of sports courts and swimming pool in a school were associated with participation in physical education classes. Availability of sports courts, running/athletics tracks, and swimming pool in schools were associated with leisure-time physical activity. Total physical activity was associated with schools with sports courts, schoolyard with teacher-directed physical activities, and swimming pool.

Conclusions

School-level characteristics have important potential to increase the possibility of engagement in physical activity in and out of school, and therefore have a fundamental role in promoting these practices.     

Presence of a Physician Safety Champion Is Associated with a Reduction in Urinary Catheter Utilization in the Pediatric Intensive Care Unit

Background

Safety champions are effective in a variety of safety initiatives; however, there are no reports of their role in hospital-acquired infections prevention.

Objective

We aimed to describe the association of the presence of a physician safety champion with our urinary catheter device utilization ratios (DUR) in the Pediatric Intensive Care Unit (PICU).

Methods

Our PICU has incidence rates of catheter-associated urinary tract infections (CAUTI) and urinary catheter DUR above the 90^th percentile. Using a quasi-experimental design, we compared our DUR when the PICU team was exposed and unexposed (champion’s maternity leaves) to a physician safety champion. Hospital acquired infection (HAI) surveillance of all PICU admissions between April 1^st 2009 and June 29^th 2013 was done prospectively. To ensure stable acuity of the patient population over time, we used the central venous catheter (CVC) DUR as a control.

Results

The urinary catheter DUR was 0.44 (95% confidence interval [CI] 0.42–0.45) during the unexposed period versus 0.39 (95%CI 0.38–0.40) during the exposed period, for an absolute difference of 0.05 (95%CI 0.03–0.06; p<0.0001). The overall CVC DUR increased from 0.57 (95%CI 0.55–0.58) during the unexposed period to 0.63 (95%CI 0.61–0.64) during the exposed period, an absolute increase of 0.06 (95%CI 0.04–0.08; p<0.0001). Comparing the exposed and unexposed periods, adjusting for time trend, we observed a 17% decrease in the urinary catheter DUR when the safety champion was present (odds ratio [OR] 0.83; 95%CI 0.77–0.90). The rate of catheter-associated urinary tract infections did not change.

Conclusions

The presence of a unit-based safety champion can have a positive impact on urinary catheter DUR in a PICU.     

Teaming up: from motors to people

When I reflect on how I became a cell biologist and why I love being one today, one thing that comes to mind is the many terrific collaborations I have had. The science I am most proud of from my graduate and postdoctoral training would not have been possible without working in teams with other scientists. Now, in my own group, much of our best work is being done collaboratively, both within the lab and with other labs. In this essay, I will highlight my experiences working in teams as a trainee, the role teamwork has played in my own research group, and how important I think collaborative science is for the future of biological research.     

Serum TNF-α, sTNFR1, IL-6, IL-8 and IL-10 levels in Weil's syndrome

Studies on cytokine levels in Weil's syndrome are lacking. In this study, TNF-α, sTNFR1, IL-6, IL-8 and IL-10 levels were measured in 44 serum samples of patients diagnosed with Leptospira interrogans serovar icterohaemorrhagiae infection. TNF-α levels linked with pulmonary hemorrhagic implications, while elevated sTNFR1 and IL-10 levels linked with fatal cases. IL-6 and IL-8 did not seem to affect the outcome of the disease. Immune response pattern in Weil's syndrome bears resemblance to other patterns described for hemorrhagic fevers. IL-10/TNF-α ratio is proposed as a marker for prognosis.     

SLIT/ROBO1 signaling suppresses mammary branching morphogenesis by limiting basal cell number

In the field of breast biology, there is a growing appreciation for the "gatekeeping function" of basal cells during development and disease processes yet mechanisms regulating the generation of these cells are poorly understood. Here, we report that the proliferation of basal cells is controlled by SLIT/ROBO1 signaling and that production of these cells regulates outgrowth of mammary branches. We identify the negative regulator TGF-β1 upstream of Robo1 and show that it induces Robo1 expression specifically in the basal layer, functioning together with SLIT2 to restrict branch formation. Loss of SLIT/ROBO1 signaling in this layer alone results in precocious branching due to a surplus of basal cells. SLIT2 limits basal cell proliferation by inhibiting canonical WNT signaling, increasing the cytoplasmic and membrane pools of β-catenin at the expense of its nuclear pool. Together, our studies provide mechanistic insight into how specification of basal cell number influences branching morphogenesis.     

Mechanism of HCV's resistance to IFN-α in cell culture involves expression of functional IFN-α receptor 1

The mechanisms underlying the Hepatitis C virus (HCV) resistance to interferon alpha (IFN-α) are not fully understood. We used IFN-α resistant HCV replicon cell lines and an infectious HCV cell culture system to elucidate the mechanisms of IFN-α resistance in cell culture. The IFN-α resistance mechanism of the replicon cells were addressed by a complementation study that utilized the full-length plasmid clones of IFN-α receptor 1 (IFNAR1), IFN-α receptor 2 (IFNAR2), Jak1, Tyk2, Stat1, Stat2 and the ISRE- luciferase reporter plasmid. We demonstrated that the expression of the full-length IFNAR1 clone alone restored the defective Jak-Stat signaling as well as Stat1, Stat2 and Stat3 phosphorylation, nuclear translocation and antiviral response against HCV in all IFN-α resistant cell lines (R-15, R-17 and R-24) used in this study. Moreover RT-PCR, Southern blotting and DNA sequence analysis revealed that the cells from both R-15 and R-24 series of IFN-α resistant cells have 58 amino acid deletions in the extracellular sub domain 1 (SD1) of IFNAR1. In addition, cells from the R-17 series have 50 amino acids deletion in the sub domain 4 (SD4) of IFNAR1 protein leading to impaired activation of Tyk2 kinase. Using an infectious HCV cell culture model we show here that viral replication in the infected Huh-7 cells is relatively resistant to exogenous IFN-α. HCV infection itself induces defective Jak-Stat signaling and impairs Stat1 and Stat2 phosphorylation by down regulation of the cell surface expression of IFNAR1 through the endoplasmic reticulum (ER) stress mechanisms. The results of this study suggest that expression of cell surface IFNAR1 is critical for the response of HCV to exogenous IFN-α.     

The microbiota influences the Drosophila melanogaster life history strategy

Organisms are locally adapted when members of a population have a fitness advantage in one location relative to conspecifics in other geographies. For example, across latitudinal gradients, some organisms may trade off between traits that maximize fitness components in one, but not both, of somatic maintenance or reproductive output. Latitudinal gradients in life history strategies are traditionally attributed to environmental selection on an animal's genotype, without any consideration of the possible impact of associated microorganisms (“microbiota”) on life history traits. Here, we show in Drosophila melanogaster, a key model for studying local adaptation and life history strategy, that excluding the microbiota from definitions of local adaptation is a major shortfall. First, we reveal that an isogenic fly line reared with different bacteria varies the investment in early reproduction versus somatic maintenance. Next, we show that in wild fruit flies, the abundance of these same bacteria was correlated with the latitude and life history strategy of the flies, suggesting geographic specificity of the microbiota composition. Variation in microbiota composition of locally adapted D. melanogaster could be attributed to both the wild environment and host genetic selection. Finally, by eliminating or manipulating the microbiota of fly lines collected across a latitudinal gradient, we reveal that host genotype contributes to latitude‐specific life history traits independent of the microbiota and that variation in the microbiota can suppress or reverse the differences between locally adapted fly lines. Together, these findings establish the microbiota composition of a model animal as an essential consideration in local adaptation.