Adiponectin secretion from cardiomyocytes produces canonical multimers and partial co-localization with calsequestrin in junctional SR

Molecular and Cellular Biochemistry - Adiponectin (ADN) is an abundant protein in serum, secreted by adipocytes, that acts as a signal for fat metabolism. It is marked by a complex molecular...     

Malignant gliomas display altered pH regulation by NHE1 compared with nontransformed astrocytes

Malignantgliomas exhibit alkaline intracellular pH (pH_i) and acidicextracellular pH (pH_e) compared with nontransformedastrocytes, despite increased metabolic H⁺ production. Theacidic pH_e limits the availability ofHCO₃, thereby reducing both passiveand dynamic HCO₃-dependent buffering.This implies that gliomas are dependent upon dynamic HCO₃-independent H⁺buffering pathways such as the type 1 Na⁺/H⁺exchanger (NHE1). In this study, four rapidly proliferating gliomas exhibited significantly more alkaline steady-state pH_i(pH_i = 7.31-7.48) than normal astrocytes(pH_i = 6.98), and increased rates of recovery fromacidification, under nominallyCO₂/HCO₃-free conditions.Inhibition of NHE1 in the absence ofCO₂/HCO₃ resulted inpronounced acidification of gliomas, whereas normal astrocytes wereunaffected. When suspended inCO₂/HCO₃ medium astrocytepH_i increased, yet glioma pH_i unexpectedlyacidified, suggesting the presence of anHCO₃-dependent acid loadingpathway. Nucleotide sequencing of NHE1 cDNA from the gliomasdemonstrated that genetic alterations were not responsible for thisaltered NHE1 function. The data suggest that NHE1 activity issignificantly elevated in gliomas and may provide a useful target forthe development of tumor-selective therapies.

     

Comparative biology of the ubiquitous Na+/H+ exchanger, NHE1: lessons from erythrocytes

By virtue of their electroneutral exchange of intracellular H+ for extracellular Na+, the Na+/H+ exchangers (NHE1-NHE8) play a pivotal role in many physiological processes. This review focuses on the ubiquitous plasma membrane isoform, NHE1. Particular attention is given to the roles and regulation of NHE1 in erythrocytes, in their own right and as model systems, but pertinent findings from non-erythroid cells are also discussed. NHE1 plays a key role in the regulation of cell volume and pH, and consequently in the control of such diverse processes as blood O2/CO2 transport, and cell proliferation, motility, and survival. Disturbances in NHE1 function are involved in important pathological states such as hypoxic cell damage and cancer development. NHE1 has a predicted topology of 12 transmembrane domains, and a hydrophilic C-terminus thought to be the major site for NHE1 regulation. NHE1 is highly conserved throughout the vertebrate phylum, particularly in the transmembrane region and the proximal part of the C-terminus. In non-erythroid, and probably also in erythroid cells, this part of the hydrophilic C-terminus interacts with multiple binding partners important for NHE1 function. Erythrocyte NHE1s from mammalian, amphibian, and teleost species are activated by cell shrinkage, decreased pH(i), inhibition of Ser/Thr protein phosphatases, and activation of Ser/Thr protein kinases, i.e., many of the stimuli activating NHE1 in non-erythroid cells. In erythrocytes of many lower vertebrates, NHE1 is activated during hypoxia and is an important modulator of hemoglobin oxygen affinity. Sensitivity of NHE1 to oxygenation status has recently been described also in non-erythroid mammalian cells.     

Barriers and facilitators to implement shared decision making in multidisciplinary sciatica care: a qualitative study

Background

Venous thromboembolism (VTE) is a common preventable cause of mortality in hospitalized medical patients. Despite rigorous randomized trials generating strong recommendations for anticoagulant use to prevent VTE, nearly 40% of medical patients receive inappropriate thromboprophylaxis. Knowledge-translation strategies are needed to bridge this gap.

Methods

We conducted a 16-week pilot cluster randomized controlled trial (RCT) to determine the proportion of medical patients that were appropriately managed for thromboprophylaxis (according to the American College of Chest Physician guidelines) within 24 hours of admission, through the use of a multicomponent knowledge-translation intervention. Our primary goal was to determine the feasibility of conducting this study on a larger scale. The intervention comprised clinician education, a paper-based VTE risk assessment algorithm, printed physicians’ orders, and audit and feedback sessions. Medical wards at six hospitals (representing clusters) in Ontario, Canada were included; three were randomized to the multicomponent intervention and three to usual care (i.e., no active strategies for thromboprophylaxis in place). Blinding was not used.

Results

A total of 2,611 patients (1,154 in the intervention and 1,457 in the control group) were eligible and included in the analysis. This multicomponent intervention did not lead to a significant difference in appropriate VTE prophylaxis rates between intervention and control hospitals (appropriate management rate odds ratio = 0.80; 95% confidence interval: 0.50, 1.28; p = 0.36; intra-class correlation coefficient: 0.022), and thus was not considered feasible. Major barriers to effective knowledge translation were poor attendance by clinical staff at education and feedback sessions, difficulty locating preprinted orders, and lack of involvement by clinical and administrative leaders. We identified several factors that may increase uptake of a VTE prophylaxis strategy, including local champions, support from clinical and administrative leaders, mandatory use, and a simple, clinically relevant risk assessment tool.

Conclusions

Hospitals allocated to our multicomponent intervention did not have a higher rate of medical inpatients appropriately managed for thromboprophylaxis than did hospitals that were not allocated to this strategy.     

The cytosolic protein kinase CK2 phosphorylates cardiac calsequestrin in intact cells

The luminal SR protein CSQ2 contains phosphate on roughly half of the serines found in its C-terminus. The sequence around phosphorylation sites in CSQ2 suggest that the in vivo kinase is protein kinase CK2, even though this enzyme is thought to be present only in the cytoplasm and nucleus. To test whether CSQ2 kinase is CK2, we combined approaches that reduced CK2 activity and CSQ2 phosphorylation in intact cells. Tetrabromocinnamic acid, a specific inhibitor of CK2, inhibited both the CSQ2 kinase and CK2 in parallel across a range of concentrations. In intact primary adult rat cardiomyocytes and COS cells, 24 h of drug treatment reduced phosphorylation of overexpressed CSQ2 by 75%. Down-regulation of CK2α subunits in COS cells using siRNA, produced a 90% decrease in CK2α protein levels, and CK2-silenced COS cells exhibited a twofold reduction in CSQ2 kinase activity. Phosphorylation of CSQ2 overexpressed in CK2-silenced cells was also reduced by a factor of two. These data suggested that CSQ2 in intact cells is phosphorylated by CK2, a cytosolic kinase. When phosphorylation site mutants were analyzed in COS cells, the characteristic rough endoplasmic reticulum form of the CSQ2 glycan (GlcNAc2Man9,8) underwent phosphorylation site dependent processing such that CSQ2-nonPP (Ser to Ala mutant) and CSQ2-mimPP (Ser to Glu mutant) produced apparent lower and greater levels of ER retention, respectively. Taken together, these data suggest CK2 can phosphorylate CSQ2 co-translationally at biosynthetic sites in rough ER, a process that may result in changes in its subsequent trafficking through the secretory pathway.     

Congenital tuberculosis associated with maternal disseminated miliary tuberculosis

Untreated tuberculosis during pregnancy presents a serious risk for transmission of disease to the newborn and can result in adverse perinatal and obstetrical outcomes. Tuberculosis during pregnancy and congenital tuberculosis are infrequent conditions and are difficult to diagnose due the non-specificity of the symptoms. A case report is presented of a woman who had no children previously with disseminated miliary tuberculosis. Tuberculosis symptoms appeared immediately after birth of the first child, with a clinical diagnosis on the second month after childbirth, whereupon the patient died. The son, a premature infant, showed disease symptoms from the first day, with primary pulmonary complex and persistent atelectasis due to bronchial obstruction. The obstruction was due to thoracic lymphadenitis and coinfection with cytomegalovirus. The infant received standard treatment and his condition improved.     

Congruence between floristic patterns of trees and lianas in a southwest Amazonian rain forest

The congruence in floristic patterns between different life-forms of woody plants remains poorly understood in tropical rain forests. We explored whether the floristic patterns of woody plants, divided into small trees 2.5–10 cm dbh, large trees ≥10 cm dbh, and lianas ≥2.5 cm dbh were associated with each other or with patterns in soil properties, elevation, and geographical distances between sample plots. We also tested whether ecological amplitudes in relation to environmental variables differed among the plant groups. Trees and lianas were inventoried in 44 0.1-ha plots, distributed among three lowland and two submontane sites in the Madidi National Park, Bolivia. Soil samples were analysed for physico-chemical properties. Floristic differences between sites (as measured with each plant group separately) yielded significant Mantel correlations with each other, and with pH, Ca, Mg, elevation and geographical distance. Mantel correlations with edaphic distances were higher for large trees than small trees, but for Mantel correlations with geographical distance the situation was reversed. Environmental and geographical distances explained 31% of the variation in floristic differences for large trees, 22% for small trees, and 10% for lianas. The ecological amplitudes of lianas were wider than those of all trees for pH, Mg and elevation. The amplitudes of the two size classes of trees did not differ. In principal coordinates ordination, the three plant groups produced similar overall floristic patterns that were explainable by environmental factors.     

Aging effects on DNA methylation modules in human brain and blood tissue

Background

Several recent studies reported aging effects on DNA methylation levels of individual CpG dinucleotides. But it is not yet known whether aging-related consensus modules, in the form of clusters of correlated CpG markers, can be found that are present in multiple human tissues. Such a module could facilitate the understanding of aging effects on multiple tissues.

Results

We therefore employed weighted correlation network analysis of 2,442 Illumina DNA methylation arrays from brain and blood tissues, which enabled the identification of an age-related co-methylation module. Module preservation analysis confirmed that this module can also be found in diverse independent data sets. Biological evaluation showed that module membership is associated with Polycomb group target occupancy counts, CpG island status and autosomal chromosome location. Functional enrichment analysis revealed that the aging-related consensus module comprises genes that are involved in nervous system development, neuron differentiation and neurogenesis, and that it contains promoter CpGs of genes known to be down-regulated in early Alzheimer's disease. A comparison with a standard, non-module based meta-analysis revealed that selecting CpGs based on module membership leads to significantly increased gene ontology enrichment, thus demonstrating that studying aging effects via consensus network analysis enhances the biological insights gained.

Conclusions

Overall, our analysis revealed a robustly defined age-related co-methylation module that is present in multiple human tissues, including blood and brain. We conclude that blood is a promising surrogate for brain tissue when studying the effects of age on DNA methylation profiles.