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[en] A sensitive radioimmunoassay for the measurement of tonin is described. It is based on the use of antibodies produced in rabbits against highly purified tonin obtained from rat submaxillary gland. A radioiodinated enzyme with high specific activity was obtained by the chloramine-T method. Optimal conditions for radioimmunoprecipitation were established and the double-antibody method was used to separate bound and free tonin. The radioimmunoassay may be used to measure tonin in amounts as low as 150 pg. This radioimmunoassay was applied to the measurement of tonin in rat saliva and in homogenates of submaxillary glands. Excellent correlation was found between tonin activity measured fluorometrically and tonin concentration obtained by the radioimmunoassay. (author)
[en] Experiments were conducted to investigate the antifungal activities of polyhexamethyleneguanidine (PHMG) derivatives introduced into polylactide (PLA), polyhydroxybutyrate (PHB) and polycaprolactone (PCL) against Aspergillus niger, Penicillium chrysogenum and Candida albicans. All of the PHMG derivatives inhibited the germination of A. niger and P. chrysogenum. All of the derivatives exerted a much stronger inhibitory effect on the cells of C. albicans. PHMG granular polyethylene wax (at the concentration of 1.0%) has a fungicidal effect. The reduction in the number of yeast cells capable of growing on the surface composites PLA, PHB and PCL with PHMG granular polyethylene wax for 24 h was R > 2. PHMG derivatives introduced into PLA decreased hydrolases activity in A. niger and P. chrysogenum. All of the PHMG derivatives introduced into all investigated polymers inhibited the hydrolases activity in C. albicans proportionately to concentration. PHMG granular polyethylene wax at a concentration of 1.0% most strongly inhibited hydrolases activity in yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packaging materials.
Graphical AbstractPHMG derivates introduced into polymer have slightly biocidal properties against molds and strong against yeast. The composites produced from PLA, PHB, PCL and this PHMG derivatives can be used in the many areas to reduce the growth of yeast. The studied composites can potentially be used for the production of biomedical or packing materials. .
[en] Cannabis use has become a hot topic in several countries due to the debate about its legalization for medical purposes. However, data are limited regarding adverse events, safety and potential impact on reproductive health. Cannabis consumption during pregnancy has been associated with gestational disorders such as preterm birth, intrauterine growth restriction, low birth weight and increased risk of miscarriage, though the underlying biochemical mechanisms are still unknown. Given that the endocannabinoid system (ECS) is involved in several reproductive processes, we tested the hypothesis that the negative outcomes may result from the impact on the ECS homeostasis caused by the main psychoactive compound of cannabis, Δ9-tetrahydrocannabinol (THC). We demonstrate that THC (10–40 µM) impairs placental endocannabinoid system by disrupting the endocannabinoid anandamide (AEA) levels and the expression of AEA synthetic and degrading enzymes N-arachidonoylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH), respectively. Although, no alterations in cannabinoid receptors CB1 and CB2 expression were observed. Thus, long-term local AEA levels are associated with a shift in the enzymatic profile to re-establish ECS homeostasis. In chronic cannabis users, high AEA levels in placenta may disturb the delicate balance of trophoblast cells turnover leading to alterations in normal placental development and foetal growth.
[en] The identification of potential damage due to chemical exposure in the workplace is a major health and regulatory concern. Traditional tests that measure both sensitization and elicitation responses require the use of animals. An alternative to this widespread use of experimental animals could have a crucial impact on risk assessment, especially for the preliminary screening of new molecules. We developed an in vitro model for the screening of potential toxic compounds. Human keratinocytes (HaCat) were used as target cells while matrix metalloproteinases (MMP) were selected as responders because they are key enzymes involved in extracellular matrix (ECM) degradation in physiological and pathological conditions. Chemical exposure was performed using nickel sulphate as a positive tester. Nickel contact induced upregulation of MMP-2 and IL-8 mRNA production. Molecular activation occurred even at very low nickel concentrations even though no phenotypic changes were observed. MMP-9 accumulation was found in the medium of treated cells with respect to controls. These observations led to the hypothesis that even minimal exposure can accumulate transcriptional activity resulting in long-term clinical signs after contact. Our simple in vitro model can be applied as a useful preliminary complement to the animal studies to screen the effects of new potential toxic compounds
[en] The modifications in brush border enzyme activity of the epithelial cell of the small intestine were studied after multiple daily fractionation (MDF) of 3 Gy X and 3 Gy X 2 X 2 (12 h split). Disaccharase and dipeptidase activities changed in the same way after irradiation. The results show that both total doses caused the three known phases of increase, decrease, and a return to normal. With MDF, activity at the end of irradiation was similar to or greater than that of controls and remained higher longer than a single dose of 8 Gy. However, the return to normal occurred sooner than after a single dose of 8 Gy. After 11 days, circadian oscillations of brush border enzyme activity appeared similar to those of controls in many segments of the intestine, reaching the highest activity during the night and the lowest in the afternoon
[en] The accessibility of the asparagine-linked carbohydrate chains of human thyrotropin (hTSH) and free α and β subunits was investigated by their susceptibility to endoglycosidases H and F as well as to peptide:N-glycosidase F. Iodinated hTSH or subunits were incubated with a commercial enzyme preparation containing both endoglycosidase F and N-glycosidase F activities and further analyzed by sodium dodecyl sulfate gel electrophoresis followed by quantitative autoradiography. The authors show that, working at the optimum of the N-glycosidase activity, the relative amount of endoglycosidase required for half-deglycosylation was 20-fold higher for native hTSH than for the reduced and dissociated subunits. Under nondenaturing conditions, the 18K β subunit of hTSH could be readily deglycosylated to a 14K species while the 22K α subunit was largely resistant. However, both subunits were converted to an apoprotein of similar apparent molecular weight of 14K following reduction of disulfide bonds. In contrast, the free α subunit of human choriogonadotropin appeared fully sensitive to carbohydrate removal under nonreducing conditions despite the presence of a partially deglycosylated 18K intermediate at low concentration of endoglycosidase. Similarly, both hTSH-α and hTSH-β could be completely deglycosylated after acid dissociation of the native hormone. While all three carbohydrate chains of hTSH are sensitive to pure peptide:N-glycosidase F, only one on α and the single oligosaccharide present on β in hTSH appeared to be cleaved by pure endoglycosidase F. These findings indicate that while the carbohydrate chain on β is not involved in αΒ association, the oligosaccharides on α are hindered when hTSH subunits are combined