Aging bone marrow mesenchymal stromal cells have altered membrane glycerophospholipid composition and functionality

Human mesenchymal stem/stromal cells (hMSC) are increasingly used in advanced cellular therapies. The clinical use of hMSCs demands sequential cell expansions. As it is well established that membrane glycerophospholipids (GPL) provide precursors for signaling lipids that modulate cellular functions, we studied the effect of the donor''s age and cell doublings on the GPL profile of human bone marrow MSC (hBMSC). The hBMSCs, which were harvested from five young and five old adults, showed clear compositional changes during expansion seen at the level of lipid classes, lipid species, and acyl chains. The ratio of phosphatidylinositol to phosphatidylserine increased toward the late-passage samples. Furthermore, 20:4n-6-containing species of phosphatidylcholine and phosphatidylethanolamine accumulated while the species containing monounsaturated fatty acids (FA) decreased during passaging. Additionally, in the total FA pool of the cells, 20:4n-6 increased, which happened at the expense of n-3 polyunsaturated FAs, especially 22:6n-3. The GPL and FA correlated with the decreased immunosuppressive capacity of hBMSCs during expansion. Our observations were further supported by alterations in the gene expression levels of several enzymes involved in lipid metabolism and immunomodulation. The results show that extensive expansion of hBMSCs harmfully modulates membrane GPLs, affecting lipid signaling and eventually impairing functionality.     

The Prevalence of and Factors Associated with Current Smoking among College of Health Sciences Students,Mekelle University in Northern Ethiopia

Background

Tobacco smoking is one of the greatest causes of preventable morbidity and mortality globally, and is responsible for many causes of untimely deaths. This survey was aimed to determine prevalence and factors associated with current smoking among the students of College of Health Sciences, Mekelle University, Ethiopia.

Methods

A cross-sectional study was employed using a structured self-administered questionnaire among College of Health Sciences students in March 2013. A stratified random sampling method was employed to select study participants. Data were entered and analysed using of Statistical Package for Social Sciences (SPSS) version 20.0.

Results

Of the 193 students, 57 (29.5%) of the students were current smokers. Most of the current smokers (89.4%) smoked between 1–10 sticks of cigarette per day. The two main reasons cited for smoking cigarettes were peer pressure (43.9%) and to relieve stress (36.8%). Being female (adjusted OR [AOR] = 0.49; 95% CI: 0.25, 0.95) and Tigre by ethnicity (AOR = 0.32; 95% CI: 0.14, 0.74) were significantly less associated with current smoking. On the other hand, being second year students (AOR = 3.84; 95% CI: 1.41, 10.46), khat chewing (AOR = 8.36; 95% CI: 2.60, 26.85) and taking illicit drugs (AOR = 10.59; 95% CI: 2.77, 40.51) were positively associated with current smoking cigarettes.

Conclusions

The current smoking prevalence among students in College of Health Sciences, Mekelle University is high and therefore, effective smoking prevention and cessation intervention programs are required to reduce smoking among university students.     

Zds2p regulates Swe1p-dependent polarized cell growth in Saccharomyces cerevisiae via a novel Cdc55p interaction domain

Deletion of the paralogs ZDS1 and ZDS2 in the budding yeast Saccharomyces cerevisiae causes a mis-regulation of polarized cell growth. Here we show a function for these genes as regulators of the Swe1p (Wee1p) kinase-dependent G2/M checkpoint. We identified a conserved domain in the C-terminus of Zds2p consisting of amino acids 813-912 (hereafter referred to as ZH4 for Zds homology 4) that is required for regulation of Swe1p-dependent polarized bud growth. ZH4 is shown by protein affinity assays to be necessary and sufficient for interaction with Cdc55p, a regulatory subunit of protein phosphatase 2A (PP2A). We hypothesized that the Zds proteins are in a pathway that negatively regulates the Swe1p-dependent G2/M checkpoint via Cdc55p. Supporting this model, deletion of CDC55 rescues the aberrant bud morphology of a zds1Δzds2Δ strain. We also show that expression of ZDS1 or ZDS2 from a strong galactose-inducible promoter can induce mitosis even when the Swe1p-dependent G2/M checkpoint is activated by mis-organization of the actin cytoskeleton. This negative regulation requires the CDC55 gene. Together these data indicate that the Cdc55p/Zds2p module has a function in the regulation of the Swe1p-dependent G2/M checkpoint.     

Phospholipid composition of packed red blood cells and that of extracellular vesicles show a high resemblance and stability during storage

Red blood cells (RBCs) are stored up to 35–42 days at 2–6 °C in blood banks. During storage, the RBC membrane is challenged by energy depletion, decreasing pH, altered cation homeostasis, and oxidative stress, leading to several biochemical and morphological changes in RBCs and to shedding of extracellular vesicles (EVs) into the storage medium. These changes are collectively known as RBC storage lesions. EVs accumulate in stored RBC concentrates and are, thus, transfused into patients. The potency of EVs as bioactive effectors is largely acknowledged, and EVs in RBC concentrates are suspected to mediate some adverse effects of transfusion. Several studies have shown accumulation of lipid raft–associated proteins in RBC EVs during storage, whereas a comprehensive phospholipidomic study on RBCs and corresponding EVs during the clinical storage period is lacking. Our mass spectrometric and chromatographic study shows that RBCs maintain their major phospholipid (PL) content well during storage despite abundant vesiculation. The phospholipidomes were largely similar between RBCs and EVs. No accumulation of raft lipids in EVs was seen, suggesting that the primary mechanism of RBC vesiculation during storage might not be raft -based. Nonetheless, a slight tendency of EV PLs for shorter acyl chains was observed.