Sorption-desorption behavior of imidacloprid in six soils collected from five coastal regions in Croatia at 20, 30 and 40°C was investigated using batch equilibrium technique. Isothermal data were ...applied to Freundlich, Langmuir and Temkin equations, and the thermodynamic parameters ΔH°, ΔG°, ΔS° were calculated. The sorption isotherm curves were non-linear and may be classified as L-type, suggesting a relatively high sorption capacity for imidacloprid. Our results showed that the K
sor
F
values decreased for all the tested soils as the temperature increased, indicating that the temperature strongly influences the sorption. Values of ΔG° were negative (−4.65 to −2.00 kJ/mol) indicating that at all experimental temperatures the interactions of imidacloprid with soils were spontaneous processes. The negative and small ΔH° values (−19.79 to −8.89 kJ/mol) were in the range of weak forces, such as H-bonds, consistent with interactions and partitioning of the imidacloprid molecules into soil organic matter. The ΔS° values followed the range of −57.12 to −14.51 J/molK, suggesting that imidacloprid molecules lose entropy during transition from the solution phase to soil surface. It was found that imidacloprid desorption from soil was concentration and temperature-dependent, i.e. at lower imidacloprid concentrations and temperature, lower desorption percentage occurred. Desorption studies revealed that hysteretic behavior under different temperature treatments existed, and it was more pronounced at 20°C in the soils with higher OC content. The study results emphasize the importance of thermodynamic parameters in controlling soil pesticide mobility in different geographical locations, seasons and greenhouse conditions.
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.
Carbon tetrachloride (CCl
4) is a well-known model compound for producing chemical hepatic injury. This study investigated the protective effects of the flavonoid luteolin on the CCl
4-induced ...hepatotoxicity in mice. Luteolin dissolved in dimethyl sulfoxide (DMSO) was administered intraperitoneally (i.p.) at 5 or 50
mg/kg as a single dose, and once daily for 2 consecutive days. Two hours after the final treatment, the mice were treated with CCl
4 (20
mg/kg, i.p.). CCl
4-induced hepatotoxicity was reduced in a dose- and time-dependent manner, as determined by decreased serum aminotransferase activities and liver histopathology. CCl
4 intoxication resulted in an overexpression of heat shock protein gp96 in the mice liver, which was strongly attenuated by luteolin pretreatment. Luteolin has also decreased oxidative stress produced by CCl
4, as suggested by improvement in the Cu/Zn superoxide dismutase activity. The effect of luteolin on myeloperoxidase, an indicator of inflammatory cell infiltration, was also investigated. Treatment of the mice with luteolin resulted in a significant decrease in the myeloperoxidase activity. The hepatoprotective effect of luteolin against CCl
4 hepatotoxicity was higher in animals pretreated with luteolin for 2 consecutive days. This suggests that the protection might be due to induction of some adaptive mechanisms. The data indicate that luteolin could be effective in protecting mice from the hepatotoxicity produced by CCl
4.
•Female and male DA rats were exposed to iron overload (IO) before immunization with BBH+CFA.•IO accelerated appearance of clinical signs of EAE in female rats.•IO accelerated the progression of EAE ...and increased mortality in male rats.•IO increased sequestration of Fe (liver, brain and spinal cord) and elevated serum ferritin in female rats.•IO induced a higher lipid peroxidation in the brain and spinal cord of male rats.
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 Freund's 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.
Environmental impact of natural gas facility near Molve (Podravina, Croatia) was assessed using hares (Lepus europaeus Pallas) as biomonitors. Elevated levels of heavy metals in the environment lead ...to their accumulation in different tissues of hares. The authors have tested accumulation and distribution of several metals in hare liver, kidney, and muscle tissues. The accumulation of copper in hare liver and kidneys with concomitant decrease of zinc was observed in animals from Podravina region as opposed to the control group of animals (Island Krk, Croatia). Secondly, the expression of metallothioneins was assessed because of their crucial role in metal homeostasis. Observed elevation of metallothionein expression in tested organs emphasizes the possible prolonged negative effects of heavy metals in the surroundings as well as a state of oxidative stress in animals. Further monitoring of the area is necessary for better control of hydrocarbon processing to diminish the possible negative environmental effects.
In the present laboratory study, persistence of imidacloprid (IMI) as a function of initial insecticide concentration and soil properties in two Croatian soils (Krk sandy clay and Istria clay soils) ...was studied and described mathematically. Upon fitting the obtained experimental data for the higher concentration level (5 mg/kg) to mathematical models, statistical parameters (R², scaled root mean squared error and χ² error) indicated that the single first-order kinetics model provided the best prediction of IMI degradation in the Krk sandy clay soil, while in the Istria clay soil biphasic degradation was observed. At the lower concentration level (0.5 mg/kg), the biphasic models Gustafson and Holden models as well as the first-order double exponential model fitted the best experimental data in both soils. The disappearance time (DT₅₀) values estimated by the single first-order double exponential model (from 50 to 132 days) proved that IMI can be categorized as a moderately persistent pesticide. In the Krk sandy clay soil, resulting DT₅₀ values tended to increase with an increase of initial IMI concentration, while in the Istria clay soil, IMI persistence did not depend on the concentration. Organic matter of both experimental soils provided an accelerating effect on the degradation rate. The logistic model demonstrated that the effect of microbial activity was not the most important parameter for the biodegradation of IMI in the Istria clay soil, where IMI degradation could be dominated by chemical processes, such as chemical hydrolysis. The results pointed that mathematical modeling could be considered as the most convenient tool for predicting IMI persistence and contributes to the establishment of adequate monitoring of IMI residues in contaminated soil. Furthermore, IMI usage should be strictly controlled, especially in soils with low organic matter content where the risk of soil and groundwater contamination is much higher due to its longer persistence and consequent leaching and/or moving from soil surface prior to its degradation.
A quick and successful procedure is presented for the separation of polar lipids, monoacylglycerols (MAGs), diacylglycerols and triacylglycerols (TAGs) and for fatty acid determination in the ...above-mentioned lipid fractions by gas chromatographic analysis, which was acceptable for physiological and nutrition studies. In the analysis of edible oils and biological tissue samples, lipid classes were separated and purified by solid-phase extraction (SPE) using an aminopropylsilica column. Fatty acids in the
sn-2 position in edible oil TAGs were determined after previous 1,3-specific lipase hydrolysis and separation of 2-MAGs by SPE using an aminopropylsilica column. A preliminary study of the solid-phase extraction separation of lipid classes with stock standard solutions using styrene–divinylbenzene–methacrylate copolymer (Nexus), octadecylsilica (C
18) and aminopropylsilica (NH
2) was carried out and it was shown that NH
2 was the best sorbent for the above-mentioned purpose.
The aim of this study was to analyze and evaluate risks of long-term exposure to mercury in hares (Lepus europaeus Pallas), with a chemical-analytical approach evaluating median mass fraction of ...toxic mercury in the hares organs (liver, kidney, muscle and brain). To obtain better insight into possible effects of mercury, the study included screening of the oxidative status after long term exposure to low concentrations of mercury. Hares organs were analyzed for total mercury concentration by AAS. Glutathione and glutathione-dependent enzymes status was also investigated. The median mercury concentrations (wet weight) in the liver, kidney, muscle and brain of the hares ranged from 0.058–0.189, 0.138–0.406, 0.013–0.046 and 0.022–0.102 μg/g respectively. Concentration of the glutathione (GSH), glutathione-peroxidase (GPx), and glutathione-reductase (GR) activity increased with the mercury concentration. However, glutathione S-transferase (GST) and superoxide-dismutase (SOD) activity decreased with the mercury concentration. The results of this study show the impact of environmentally absorbed mercury on the antioxidant status of the examined hares. Further research on long-term exposure to low concentrations of mercury is needed.
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, KFˢᵒʳ 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, KFᵈᵉˢ, 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.
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