Jelena Marinić

Hysteretic Behavior of Imidacloprid Sorption-Desorption in Soils of Croatian Coastal Regions

Sorption and desorption are important processes that influence the transport, transformation, and bioavailability of imidacloprid in the soils. Equilibrium batch experiments were carried out using six coastal Croatian soils. The equilibrium sorption and desorption experimental data showed the best fit to the Freundlich equation. Sorption parameters predicted with the Freundlich model, KF sor and 1/n ranged from 2.92 to 5.74 (mg/kg)/(mg/L)1/n, and 0.888 to 0.919, respectively. The sorption of imidacloprid was found to be sensitive to organic carbon (OC) content. The highest sorption was observed in Krk soil (OC 4.74%) and the lowest in Zadar soil (OC 1.06%). Fitted desorption parameter values, KF des , were consistently higher than those associated with sorption. The opposite trend was observed for the exponential parameter 1/n. Results also suggested that imidacloprid sorption-desorption by soil is concentration-dependent, i.e. at lower imidacloprid concentrations a greater sorption percentage and lower desorption percentage occurred. Desorption studies revealed that there was a hysteresis effect in all the tested soils. Hysteresis coefficient values (H) varied from 0.656 to 0.859. The study results emphasize that the controlled application of imidacloprid is obligatory, especially in soils with a low organic carbon content, in order to minimize a risk of environmental and groundwater pollution.

Urinary metabolomic fingerprinting after consumption of a probiotic strain in women with mastitis

Infectious mastitis is a common condition among lactating women, with staphylococci and streptococci being the main aetiological agents. In this context, some lactobacilli strains isolated from breast milk appear to be particularly effective for treating mastitis and, therefore, constitute an attractive alternative to antibiotherapy. A (1)H NMR-based metabolomic approach was applied to detect metabolomic differences after consuming a probiotic strain (Lactobacillus salivarius PS2) in women with mastitis. 24h urine of women with lactational mastitis was collected at baseline and after 21 days of probiotic (PB) administration. Multivariate analysis (OSC-PLS-DA and hierarchical clustering) showed metabolome differences after PB treatment. The discriminant metabolites detected at baseline were lactose, and ibuprofen and acetaminophen (two pharmacological drugs commonly used for mastitis pain), while, after PB intake, creatine and the gut microbial co-metabolites hippurate and TMAO were detected. In addition, a voluntary desertion of the pharmacological drugs ibuprofen and acetaminophen was observed after probiotic administration. The application of NMR-based metabolomics enabled the identification of the overall effects of probiotic consumption among women suffering from mastitis and highlighted the potential of this approach in evaluating the outcomes of probiotics consumption. To our knowledge, this is the first time that this approach has been applied in women with mastitis during lactation.

Metallothionein expression and tissue metal kinetics after partial hepatectomy in mice

To better elucidate previous results showing that partial hepatectomy noticeably changes the tissue content of zinc, calcium, magnesium, and iron(II) ions in regenerating the liver, thymus, and spleen, we report on the correlation of these metal tissue kinetics in these organs with the expression of metallothionein-I+II (MT-I+II) proteins and MT-I mRNA in early postoperative period (1, 2, 6, 12, and 24 h) after one-third hepatectomy (pHx). The results showed that 2 h after pHx the regenerating liver accumulated Zn2+, Ca2+, Mg2+, and Fe2+ ions while decreasing the concentration of all these metals in the spleen and of Zn2+ in the thymus. On the 24th h, a new high accumulation of Zn2+ and Ca2+ was seen in the regenerating liver and of Zn2+, Ca2+, and Fe2+ in the spleen. Simultaneously, MT-I mRNA increased in the liver and spleen. In hepatocytes and on several spleen and thymus mononuclear lymphatic cells, the increased expression of MT proteins was found mainly in the cytoplasm and nuclei. The areas expressing MTs in regenerating liver inversely correlated with those containing apoptotic cells, suggesting that these proteins participate in tissue restoration through reduction or increase of metal ions after injury to the liver.

Preexposure to Olive Oil Polyphenols Extract Increases Oxidative Load and Improves Liver Mass Restoration after Hepatectomy in Mice via Stress-Sensitive Genes

Polyphenols can act as oxidants in some conditions, inducing redox-sensitive genes. We investigated the effect of preexposure to the olive oil polyphenols extract (PFE) on time-dependent changes in the hepatic oxidative state in a model of liver regeneration—a process in which oxidative stress associated with the metabolic overload accounts for the early events that contribute to the onset of liver self-repair. Liver regeneration was induced by one-third hepatectomy in mice. Prior to hepatectomy, mice were intraperitoneally given either PFE (50 mg/kg body weight) or saline for seven consecutive days, while respective controls received vehicle alone. Redox state-regulating enzymes and thiol proteins along with the mRNA levels of Nrf2 gene and its targets γ-glutamylcysteine synthetase and heme oxygenase-1 were determined at different time intervals after hepatectomy. The liver mass restoration was calculated to assess hepatic regeneration. The resulting data demonstrate the effectiveness of preexposure to PFE in stimulating liver regeneration in a model of a small tissue loss which may be ascribed to the transient increase in oxidant load during the first hours after hepatectomy and associated induction of stress response gene-profiles under the control of Nrf2.

Behavior and Fate of Imidacloprid in Croatian Olive Orchard Soils Under Laboratory Conditions

The sorption-desorption and degradation of IMI was examined to understand the influence of concentration and soil properties on its behavior and fate in soils of Croatian coastal regions. The experimental data revealed that the sorption and desorption isotherms of IMI in the tested soils were nonlinear over the concentration range used, which can be best described by the Freundlich equation. Soil sorption capacity of IMI depended significantly on the soil properties. Especially, the sorption behavior of IMI was largely dependent on the soil OC content, where the soils with higher OC content (Istria soils) showed higher sorption capacity and less potential mobility of IMI. Given the spatial difference between tested soils, statistically significant differences in soil sorption capacity were found among and within soils of Istrian and Krk region. According to calculated KOC values, IMI can be categorized as a medium mobility pesticide indicating that rational use of IMI entails little danger of the ground-water contamination. In all soils, a higher sorption capacity was observed at lower IMI concentrations, indicating that the percentage of desorbed amount of pesticide increased with increasing initial solution concentration. Desorption experimental data deviated significantly from the sorption data, indicating that these processes were distinctly different in tested soils. It can be assumed, that the desorption process appeared to be the result of a complex, time dependent interplay of several chemical and physical processes and irreversible binding of IMI to soil surfaces, leading to hysteresis. The negative and low values of the Gibbs free energy of the IMI sorption indicated exotermic characteristics of sorption reaction and corresponded to the physical process, suggesting that partitioning into soil organic matter was the main mechanism of IMI sorption in the soils used. IMI kinetic behavior in all tested soils at the high concentration level can be described by the first-order kinetic degradation model, except for Istria II soil, where biphasic kinetics was observed. In contrast, at the low concentration level, the two-compartment kinetic model took place, characterized by the fast initial phase in the first 15 days of degradation followed by a slow degradation phase up to 180 days. According to the pesticide persistence classification, IMI can be categorized as moderately persistent pesticide (DT50 from 50 – 165 days), showing that the slow degradation of IMI in the tested soils further enlarges the danger of environmental damage. Concentration level significantly affected IMIs degradation, where higher persistence of IMI at higher initial concentration level was observed. In all tested soils, organic matter provided an accelerating effect on the degradation rate. The study results emphasize the need for controlled IMI usage, especially in soils with low humus content (Krk soils), thus avoiding a risk of IMI leeching. Considering the abundant current use of IMI in the Croatian olive growing areas, regular monitoring is needed to evolve a strategy to manage the environmental hazards due to the IMI and its degradation products. Further research, aided also with the actual field data, will be directed to investigate the IMIs metabolism and binding mechanisms in order to better understand degradation pathway and the causes for hysteresis phenomena.

Chronic iron overload induces gender-dependent changes in iron homeostasis, lipid peroxidation and clinical course of experimental autoimmune encephalomyelitis

To analyze iron- and gender-dependent mechanisms possibly involved in pathogenesis of multiple sclerosis (MS) in this study we evaluated the effects of iron overload (IO) on iron status and lipid peroxidation processes (LPO) in tissues of female and male DA rats during chronic relapsing experimental autoimmune encephalomyelitis, a well-established MS animal model. Rats were treated by iron sucrose (75mg/kg bw/day) or with saline solution during two weeks before the sensitization with bovine brain homogenate in complete Freunds adjuvant. Clinical signs of EAE were monitored during 29 days. Serum and tissues of CNS and liver were sampled before immunization and at day 13th post immunization (during acute phase of EAE). The determination of ferritin, iron, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) and evaluation of histopathology were performed by ELISA, ICP spectrometry and immunohistochemistry. Results showed that IO in female EAE rats accelerated the onset of disease. In contrast, in male rats it accelerated the progression of disease and increased the mortality rate. During acute phase of EAE female IO rats sequestered more Fe in the liver, spinal cord and in the brain and produced more ferritin than male EAE rats. Male rats, however, reacted on IO by higher production of MDA or 4-HNE in the neural tissues and showed greater signs of plaque formation and gliosis in spinal cord. The data point to sexual dimorphism in mechanisms that regulate peripheral and brain iron homeostasis and imply that men and women during MS might be differentially vulnerable to exogenous iron overload.

Kinetics of Tissue Iron in Experimental Autoimmune Encephalomyelitis in Rats

To elucidate the role of iron in the pathomechanisms of autoimmune CNS disorders, we estimated the tissue concentrations of Fe2+ in the brain, spinal cord, and liver in the chronic relapsing form of experimental autoimmune encephalomyelitis (EAE). The disease was induced in Dark Agouti (DA) strain of rats, by subcutaneous injection of bovine brain homogenate in complete Freunds adjuvant (CFA). Control rats consisted of unsensitized rats and of rats treated with CFA or saline. The data obtained by clinical assessment and by inductively coupled plasma spectrometry have shown that the attacks of disease (on the 12th and 22nd post-immunization day) were followed by high accumulation of iron in the liver. Additionally, during the second attack of disease, the decreased concentration of Fe2+ was found in cervical spinal cord. The data point to regulatory effects of iron and hepatic trace elements regulating mechanisms in the pathogenesis of EAE.

Metallothioneins and trace elements dyshomeostasis induced by exposure to gasoline vapor in mice

To investigate the effects of air pollution related with the gasoline/petrochemical industry the expression of metallothionein I (MT-I) mRNA and tissue metals were analyzed in organs of mice, exposed to gasoline (G) vapor in laboratory conditions. Control groups consisted of intact mice and of those exposed in the metabolic chamber to fresh air. The data obtained by RT-PCR and inductively coupled plasma spectrometry have shown that exposure to G vapor leads to upregulation of MT-I mRNA in organs that receive a strong respiratory and olfactory input or participate in gasoline degradation and elimination (lungs, brain, kidney and liver). Besides, in the brain and in the lungs, kidney and liver a decreased tissue content of Zn²⁺ or Cu²⁺ and Mg²⁺ was found (p<0.001). Some of these changes were obtained also in mice closed in the metabolic chamber, pointing to the involvement of stress-induced mechanisms in the transcriptional regulation of MTs.

Soil sorption characteristics of imidacloprid in different Croatian regions

In Croatia, imidacloprid is increasingly used in olive growing areas against the olive fruit fly. Experiments were conducted to examine the relationship between soil properties, imidacloprid concentration and soil sorption capacity. The linear and the Freundlich model adequately described the imidacloprid sorption. Better sorption was observed at lower imidacloprid concentrations and in soils with higher organic carbon and clay content, but organic carbon content was predominant factor influencing sorption. Thus, for soils with lower sorption capacity a greater potential mobility of imidacloprid in the soil profile is expected, indicating a need for regular monitoring and strategy development against groundwater pollution.