Publications by authors named "Iva Simic"

In this paper, the authors investigated changes in mass concentrations of particulate matter (PM) during the Coronavirus Disease of 2019 (COVID-19) lockdown. Daily samples of PM, PM and PM fractions were measured at an urban background sampling site in Zagreb, Croatia from 2009 to late 2020. For the purpose of meteorological normalization, the mass concentrations were fed alongside meteorological and temporal data to Random Forest (RF) and LightGBM (LGB) models tuned by Bayesian optimization.

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First data on polycyclic aromatic hydrocarbons (PAHs) and nitro-aromatic compounds (NACs) in aerosols as well as of PAHs, polychlorinated biphenyls (PCBs) and NACs in bulk and wet atmospheric deposition samples were simultaneously obtained during 6-month-long field campaign at the costal central Adriatic area. Special attention was given to open-fire biomass burning episodes as extreme events common for the overall Mediterranean coastal area in order to gain a better understanding of the atmospheric variabilities and potential sources of trace organic pollutants in coastal environments. Diesel and gasoline combustion related to land and maritime traffic as well as occasional open-fire episodes (forest fires) were found to be the dominant pollution sources of PAHs in PM particles.

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A method based on solid phase extraction (SPE), gas chromatography tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron capture detector (GC-ECD) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in atmospheric deposition samples. Six indicator PCB congeners were analysed by GC-ECD equipped with two micro electron-capture detectors and two gas chromatographic columns, while 12 PAH compounds were analysed by GC-MS/MS. Solid phase extraction on silica sorbent proved suitable for accumulation of PAHs and PCBs from deposited matters.

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In this study, equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The K parameter from linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin-Radushkevich (D-R) sorption models were applied to describe the equilibrium isotherms by linear and nonlinear methods.

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The mechanism of maladaptive chronic stress response involves altered phosphorylation of the glucocorticoid receptor (GR). In this study, we investigated if important depressogenic vulnerability factors, such as neuroticism and self-reports of negative affective states, may be associated with alterations in levels of the GR and GR phosphoisoforms in peripheral blood mononuclear cells (PBMC) of healthy adults. In 21 women and 16 men we evaluated PMBC levels of total GR (tGR), GR phosphorylated at serine 211 (pGR-S211) and serine 226 (pGR-S226) and correlated these data with personality traits and current reports of stress, anxiety and depression.

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Chronic psychosocial isolation stress (CPSI) modulates glucocorticoid receptor (GR) functioning in Wistar male rat hippocampus (HIPPO) through alteration of nuclear GR phosphorylation and its upstream kinases signaling, which parallels animal depressive-like behavior. The current study investigated potential gender specificities regarding the effect of chronic therapy by an antidepressant fluoxetine (FLU) on GR signaling in HIPPO and depressive-like behavior in CPSI animals. FLU was administrated to female and male naïve or CPSI rats for 21 days and GR protein, its phosphorylation status and upstream kinases, as well as GR and BDNF mRNA were followed in HIPPO together with animal serum corticosterone (CORT) and depressive-like behavior.

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The impaired glucocorticoid receptor (GR) signaling has long been considered one of the cornerstones in understanding the pathophysiology of depression. Since the phosphorylation of GR is very important for GR function, in this study we investigated whether GR phosphorylation at serine 211 (pGR-S211) and serine 226 (pGR-S226) is altered in patients with current episode of major depressive disorder (MDD). Particularly, in 30 MDD patients and 35 controls we assessed the levels of nuclear total GR (tGR), pGR-S211 and pGR-S226 in peripheral blood mononuclear cells (PBMC) using Western blot technique, along with plasma cortisol concentrations from the same blood samples.

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Article Synopsis
  • * The study investigated how CPSI affects glucocorticoid receptor (GR) levels and heat shock proteins (HSPs), which are important for stress response, in the hypothalamus during acute stress.
  • * Findings revealed that while normal rats showed increased GR and HSP levels during stress, CPSI rats had altered GR and HSP responses, suggesting CPSI may negatively impact stress regulation in the brain.
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Alterations in the antioxidative defense parameters upon chronic stress are considered critical for pathophysiology of stress related psychiatric disorders, and their status in blood serves as biomarker for effects of pharmacological treatments. The present study was designed to investigate the modulation of erythrocyte antioxidant enzymes (AOEs): CuZn superoxide dismutase (CuZnSOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GLR) activities and their protein expression in Wistar male rats subjected to chronic psychosocial isolation and/or to pharmacological treatment with fluoxetine. Chronically isolated animals exhibited decreased levels of serum corticosterone, as opposed to other chronic stress paradigms.

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