The aim of the study was to evaluate the activity of glutathione peroxidase (GSH-Px) and the concentration of selenium in Holstein-Friesian cows at different stages of lactation. Selenium was determined spectrofluorimetrically and GSH-Px activity using a Sigma CGP1 Glutathione Peroxidase Cellular Activity Assay kit. Mean serum selenium concentration was highest in early-lactation multiparous cows (0.18 μg/ml) and the lowest in dry cows (0.111 μg/ml). In early lactation, serum selenium concentration was significantly (P ≤ 0.01) higher in multiparous cows than in cows from the other groups. Mean GSH-Px activity in the serum of dry cows was over twice lower than in late-lactation cows (P ≤ 0.01) and over four times lower than in first-calving heifers and multiparous cows in early lactation (P ≤ 0.01). The coefficients of Spearman's rank correlation between GSH-Px activity and selenium concentration in the cows at different stages of lactation were not significant. A significant (P ≤ 0.01) mean positive correlation (0.46) was found between GSH-Px activity and serum selenium concentration for all the cows analysed together. The highest Se concentration and GSH-Px activity found in the serum of cows during the first stage of lactation may suggest that the generation of reactive oxygen species and their derivatives was higher during this period compared to the other stages, thus placing the cows at a greater risk of oxidative stress. It is therefore essential to give particular attention during this period to meeting the cows' requirement for selenium and other feed components that increase, directly or indirectly, the capacity of the body's antioxidant system.

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In this work, we present novel ex situ modification of bacterial cellulose (BC) polymer, that significantly improves its ability to absorb water after drying. The method involves a single inexpensive and easy-to-perform process of BC crosslinking, using citric acid along with catalysts, such as disodium phosphate, sodium bicarbonate, ammonium bicarbonate or their mixtures. In particular, the mixture of disodium phosphate and sodium bicarbonate was the most promising, yielding significantly greater water capacity (over 5 times higher as compared to the unmodified BC) and slower water release (over 6 times as compared to the unmodified BC). Further, our optimized crosslinked BC had over 1.5x higher water capacity than modern commercial dressings dedicated to highly exuding wounds, while exhibiting no cytotoxic effects against fibroblast cell line L929 in vitro. Therefore, our novel BC biomaterial may find application in super-absorbent dressings, designed for chronic wounds with imbalanced moisture level.

Introduction: According to a review of the literature, there is a lack of data on the mechanisms that participate in the suppression of inflammation that accompanies polycystic ovary syndrome (PCOS). Additionally, the changes in oxidative status resulting from a low-calorie diet have not been studied in a group of women with PCOS, and the oxidation and reduction processes associated with PCOS have not been explained. Material and methods: The study involved 49 women who were diagnosed with PCOS according to Rotterdam’s criteria, and 24 women voluntarily agreed to a three-month dietary intervention. The dietary intervention was carried out for 3 months. Glutathione peroxidase (GPx3) activity, the Ferric reducing ability of plasma, and uric acid concentration were measured spectrophotometrically both before and after the intervention. Statistical analysis was performed with the Statistica 10.0 software package, and a Pearson’s correlation matrix was generated. Results: A lower concentration of GPx3 was observed in women with PCOS (before the dietetic intervention began) compared with the GPx3 levels in healthy women. A relationship was shown between GPx3 levels and the concentration of prolactin, insulin on fasting, and triglycerides. After the dietary intervention, increases in uric acid and GPx3 activity were noted, as well as numerous relationships between anthropometric and biochemical parameters. The ferric reducing/antioxidant power did not change significantly. Conclusions: Inhibiting the effect of prolactin (by the level of reactive oxygen species) on the activity of GPx3 could be a starting point for the increase in antioxidative stress and the development of the inflammatory state associated with PCOS pathophysiology. Following a low-calorie diet with a lower glycemic index is proposed to silence inflammation by increasing the concentration of uric acid. During GPx3 mobilization, women with PCOS have a higher demand for selenium, and its deficiencies may contribute to disordered thyroid hormone synthesis. The three-month dietary intervention did not silence redox processes in the examined group of women.

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The aim of this study was to analyse the effect of rotating magnetic field (RMF) exposition on the fungal laccase catalytic properties. The results obtained in the study revealed that RMF may positively alter the laccase activity. A significant increase in activities of 11%, 11%, and 9% were observed at 10 Hz, 40 Hz and 50 Hz, respectively. Exposure of laccase to the rotating magnetic field resulted in its increased activity at broader pH range and a slight shift in optimum pH from 4.0 to 4.5 at RMF with frequency 20 Hz. The results show that the enzyme activity, stability, and optimum pH can be significantly altered depending on the characteristic of the applied RMF. Application of rotating magnetic field opens a new way for controlling and directions of enzyme-based bioprocessing.