Hepcidin-mediated Iron Regulation in P19 Cells is Detectable by Magnetic Resonance Imaging.

Magnetic resonance imaging can be used to track cellular activities in the body using iron-based contrast agents. However, multiple intrinsic cellular iron handling mechanisms may also influence the detection of magnetic resonance (MR) contrast: a need to differentiate among those mechanisms exists. In hepcidin-mediated inflammation, for example, downregulation of iron export in monocytes and macrophages involves post-translational degradation of ferroportin. We examined the influence of hepcidin endocrine activity on iron regulation and MR transverse relaxation rates in multi-potent P19 cells, which display high iron import and export activities, similar to alternatively-activated macrophages. Iron import and export were examined in cultured P19 cells in the presence and absence of iron-supplemented medium, respectively. Western blots indicated the levels of transferrin receptor, ferroportin and ubiquitin in the presence and absence of extracellular hepcidin. Total cellular iron was measured by inductively-coupled plasma mass spectrometry and correlated to transverse relaxation rates at 3 Tesla using a gelatin phantom. Under varying conditions of iron supplementation, the level of ferroportin in P19 cells responds to hepcidin regulation, consistent with degradation through a ubiquitin-mediated pathway. This response of P19 cells to hepcidin is similar to that of classically-activated macrophages. The correlation between total cellular iron content and MR transverse relaxation rates was different in hepcidin-treated and untreated P19 cells: slope, Pearson correlation coefficient and relaxation rate were all affected. These findings may provide a tool to non-invasively distinguish changes in endogenous iron contrast arising from hepcidin-ferroportin interactions, with potential utility in monitoring of different macrophage phenotypes involved in pro- and anti-inflammatory signaling. In addition, this work demonstrates that transverse relaxivity is not only influenced by the amount of cellular iron but also by its metabolism.

MagA expression attenuates iron export activity in undifferentiated multipotent P19 cells.

Magnetic resonance imaging (MRI) is a non-invasive imaging modality used in longitudinal cell tracking. Previous studies suggest that MagA, a putative iron transport protein from magnetotactic bacteria, is a useful gene-based magnetic resonance contrast agent. Hemagglutinin-tagged MagA was stably expressed in undifferentiated embryonic mouse teratocarcinoma, multipotent P19 cells to provide a suitable model for tracking these cells during differentiation. Western blot and immunocytochemistry confirmed the expression and membrane localization of MagA in P19 cells. Surprisingly, elemental iron analysis using inductively-coupled plasma mass spectrometry revealed significant iron uptake in both parental and MagA-expressing P19 cells, cultured in the presence of iron-supplemented medium. Withdrawal of this extracellular iron supplement revealed unexpected iron export activity in P19 cells, which MagA expression attenuated. The influence of iron supplementation on parental and MagA-expressing cells was not reflected by longitudinal relaxation rates. Measurement of transverse relaxation rates (R2* and R2) reflected changes in total cellular iron content but did not clearly distinguish MagA-expressing cells from the parental cell type, despite significant differences in the uptake and retention of total cellular iron. Unlike other cell types, the reversible component R2' (R2* ‒ R2) provided only a moderately strong correlation to amount of cellular iron, normalized to amount of protein. This is the first report to characterize MagA expression in a previously unrecognized iron exporting cell type. The interplay between contrast gene expression and systemic iron metabolism substantiates the potential for diverting cellular iron toward the formation of a novel iron compartment, however rudimentary when using a single magnetotactic bacterial gene expression system like magA. Since relatively few mammalian cells export iron, the P19 cell line provides a tractable model of ferroportin activity, suitable for magnetic resonance analysis of key iron-handling activities and their influence on gene-based MRI contrast.

Prevalence and Genotype Characterization of Blastocystis hominis Among the Baghmalek People in Southwestern Iran in 2013 - 2014.

BACKGROUND: Blastocystis hominis is a common globally distributed parasite. The prevalence of this parasite has been shown to vary among different countries. Molecular studies have also shown that there is a high level of genetic diversity among Blastocystis spp. isolated from humans and animals. Extensive information on parasitic genotypes will aid in devising more effective strategies for the identification and potential control of these pathogenic parasites. OBJECTIVES: This study aimed to gain information on the prevalence and abundance of Blastocystis subtypes in Iran. MATERIALS AND METHODS: Over a period of 3 months, 1,410 stool samples were collected and examined by microscopy. Samples found to be positive for B. hominis were concentrated and phylogenetic analysis was subsequently performed. A questionnaire was completed by all study participants. RESULTS: Blastocystis hominis was found to have a prevalence of 3.33% in the study population. There was no significant association of Blastocystis infection with age (P = 0.3) or gender (P = 0.57). The Blastocystis subtypes (ST) identified in this study were ST3, ST4, ST5, and ST7 with the most prevalent being ST4 (40.9%). CONCLUSIONS: The prevalence of B. hominis in the study area was lower than that reported for most developed countries, and unlike in other countries in the Middle East, ST4 was the most prevalent subtype.

The Relationship between Sleep Quality and Social Intimacy, and Academic Burn-Out in Students of Medical Sciences.

INTRODUCTION: Academic burnout leads to creation of a series of negative and scattered thoughts, loss of hope and emotional and physical exhaustion in carrying out activities. Two factors that affect academic burnout are sleep quality and social intimacy. This study was conducted in order to investigate the relationship between sleep quality and social intimacy, and academic burn-out in the students of Tabriz University of Medical Sciences. MATERIALS & METHODS: This study was descriptive and correlational. The population of this study consisted of the students in Tabriz University of Medical Sciences and 196 medical students were selected. They completed Berso et al. Academic Burnout Questionnaire, Pittsburgh Sleep Quality Index (PSQI) and Miller Social Intimacy Scale (MSIS). The validity of the questionnaires confirmed by experts' views. Their reliability were obtained as 77%, 64% and 85% for academic burnout, sleep quality and social intimacy questionnaires respectively by calculating the internal consistency (Cronbach's alpha). For data analysis, descriptive statistics and Pearson correlation test, Regression, cluster analysis and t-test were used. RESULTS: The results showed that there was a positive and significant relationship between sleep quality and academic burnout at the level p<0.05 (r=0.38). There was a negative and significant relationship between social intimacy and academic burnout at the level p<0.05 (r= -0.40). Also, the regression results showed that sleep quality and social intimacy were able to predict 37% and 39% of academic burnout respectively. Moreover, the students were divided into two clusters of individuals with high social intimacy and individuals with low social intimacy. No significant difference was found between the two types in terms of the variable of academic burn-out. CONCLUSION: Based on the research results, it can be stated that the variables of sleep quality and social intimacy are the predictor factors of academic burn-out.