National Repository of Grey Literature 101 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Vliv selenu a vitamínu E na kvalitu masa vykrmovaných býků
Navrátilová, Eliška
A control and an experimental group of bulls were set up for the experiment. The bulls were fed the same total mixed ration. The experimental group had this total mixed ration by the addition of vitamin E and selenium. The whole experiment lasted for 90 days. The bulls were weighed at monthly intervals. At the end of the experiment, the bulls were slaughtered at the slaughterhouse. Samples were taken from the muscle, which were wrapped and stored in a refrigerator. Individual analyses were conducted for a total of 4 weeks, from week 0 to week 4 of maturation. Analysis for selenium content and sensory properties of the meat was carried out at the beginning and at the end of maturation. The result showed that the addition of selenium and vitamin E to the total mixed ration did not affect weight and gain. The selenium content in the meat of the experimental group was higher and increased during maturation, while that of the control group was lower and gradually decreased. As the selenium content of the meat increased, the sensory parameters evaluated also improved, whereas the results of the control group were similar at weeks 1 and 4 of maturation.
Reduction of polyatomic interferences in As and Se determination by ICP-MS
Vajnahij, Volodymyr ; Nováková, Eliška (advisor) ; Hraníček, Jakub (referee)
This bachelor thesis was focused on the eliminationof polyatomic interferences in the determination of As and Se using inductively coupled plasma mass spectrometry. For this purpose, the collision-reaction cell technique was employed. The collision-reaction cell was filled with either collision gas or collision-reaction gas, namely pure He and H2, at different flow rates.In the case of the determinationof arsenic,which is monoisotopic and therefore no isotope other than 75 As can be selected, one of the main polyatomic interferences is 40 Ar35 Cl+ , which has the same mass-to-charge ratio m/z = 75 as 75 As. In the case of selenium determination, there are isobaric interferences due to 40 Ar38 Ar+ , 40 Ar40 Ar+ and 38 Ar40 Ca+ affecting the measurement of 78 Se and 80 Se. When 78 Se was determined in the He mode with 5 ml ∙ min-1 , a 300-fold decrease in BEC was observed. At the same time, this collision gas flow rate is higher than the routinely used one and thus able to remove more polyatomic interferences caused by 40 Ar38 Ar+ and 38 Ar40 Ca+ , respectively.Aslight improvement in some parameters was also achieved by using the H2 mode, which is more effective in reducing polyatomic interferences in the determination of Se than the He mode. With the removal of argide interference, H2 reaction...
Photocatalysed Se Volatile Species Generation
Remperová, Natália ; Nováková, Eliška (advisor) ; Musil, Stanislav (referee)
Vapour generation techniques introduce the sample in the gas phase into the atomic absorption spectrometry detector. These generation techniques help to overcome the limitations of liquid sample introduction and allow to determine trace elements in different matrices. UV-photochemical generation is one of the techniques used for the generation of volatile species. Less harmful chemicals, minimisation of waste, more affordable analysis, or improved limits of detection are only a few benefits that this technique brings to the sample introduction techniques for spectrometric detectors in analytical chemistry. Selenium is one of the most studied elements by vapour generation techniques. However, a study of catalysed UV-photochemical generation of Se volatile species coupled with atomic absorption spectrometry detection and reliable determination of generation efficiency has not been published so far. The aim of this master project is to develop a method for the photochemical generation of Se volatile species from Se(IV) and Se(VI). Different photocatalysts are tested for the generation and their elemental composition, structure and size are investigated. First, the apparatus was assembled based on the information in the published literature and previous experiences of the researchers from our group....
Toxicita selenových nanočástic v živočišném organismu
Hledíková, Jana
The aim of this study was to verify the toxicity of selenium nanoparticles in an animal organism. Wistar albino rats were divided into five groups. Four groups of rats were fed a monodiet with added SeNP at doses of 0,5; 1,5; 3,0 and 5,0 mg Se/kg per feed dose. The experiment lasted 28 days. During this, the weight of the animals was measured every 7 days (0, 7, 14, 21, 28). After putting to death the animals at the end of the experiment, some blood parameters and histopathology of selected tissues were determined. Total antioxidant capacity (TAC), glutathione peroxidase (GPx), superoxide dismutase (SOD), alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glucose, total protein and albumin were diagnosed in the blood. Blood and liver selenium levels were analyzed and liver function tests were performed. Histopathological evaluation of liver and intestinal tissue was performed. The weight gain of the rats did not show differences between the tested groups. Compared to the control group, the selenium content in the blood and liver increased in the tested groups. However, selenium content in the liver did not increase in the test groups in a dose-dependend manner. No differences in TAC and ALP and AST aktivity were found. A significant reduction in ALT aktivity was observed in the test groups compared to the control group. SOD aktivity was reduced in the SeNP test group with 5 mg Se/kg compared to all other groups. GPx aktivity had a slightly increasing trend depending on the dose of SeNP, but without a significant (p <0,05) effect. Histopathological examination revealed damage to the hepatic parenchyma and intestinal epithelium that was dose-dependend on SeNP. From this study, it can be concluded that short-term supplementation of SeNP may be safe and beneficial, for example in selenium deficiency or for therapeutic purposes.
Efekt selenu na antioxidační status organismu po porodu
Wronková, Sabina
The aim of this thesis was to develop a literature search and experimentally determine the effect of organic forms of selenium levels (0.3 and 0.6 mg/kg FM) of selenium on the antioxidant status in postpartum sows. Experiment included 18 sows in the postpartum period, which were divided into three groups according to age. The model animals were divided into three groups. The first group (Se1) sows (n = 6) served as a control, wherein the addition of selenium has not been increased. The second group (Se2) sows (n = 6) were fed 0.3 mg Se/kg FM. Third group (Se3) sows (n = 6) were fed 0.6 mg Se/kg FM. Premix was dosed in the morning feeding. To supplement selenium were used selenium enriched yeast (Sel-Plex - Alltech's). The results show that the dose of selenium in an amount of 0.30 and 0.60 mg/kg FM, increase the activity of antioxidant enzymes, glutathione peroxidase and superoxide dismutase. Glutathione peroxidase (GPx) after supplementation with 0.3 mg/kg selenium increased from the second sampling, but the third sampling was statistically significant (P <0.05). Doses of 0.6 mg/kg selenium also visibly increased level of glutathione, but these results can not be statistically demonstrated. Superoxide dismutase (SOD) at both doses (0.3 and 0.6 mg/kg) appeared selenium statistically not detectable visible growth. We also found an increase of antioxidant activity measured by the methods ABTS, FRAP and FR, although the methods ABTS and FR showed slight fluctuations. The amount of reduced and oxidized glutathione were also significantly (P <0.05) higher in both experimental groups. The selenium content of selenium supplementation significantly affected when the results of both experimental groups were statistically significant (P <0.05) higher. Level malonyldialdehydu (MDA) after supplementation with 0.3 mg/kg selenium statistically proven (P <0.05) increased in the third collection at 0.6 mg/kg selenium, we observed statistically demonstrable (P <0.05) increase from the second collection. We can therefore conclude that selenium supplementation in organic form, can reduce oxidative stress in confinement of sows and overcome this stressful period for the organism.
Mikroelementy a imunitní systém
HODAN, Lukáš
The immune system is an example of the body's ability to maintain its homeostasis and adaptability to external and internal environments. Microelements are an essential part of the proper functioning of the immune system. Quarantine can be as harmful as an excess of individual elements. The presented bachelor thesis deals with the immune system, especially the influence of microelements on its proper function. The individual chapters describe cells, molecules, organs and abnormalities of improper development. A significant part is devoted to microelements, occurrence, absorption, transport, influence on the immune system, deficiency and toxicity and their consequences.
Impact of various selenium supplements offered sheep on lambs´vitality
HUPKOVÁ, Petra
The aim of my thesis was to compare the effects of selenium in organic form (bound to Chlorella algae and to yeast) and of selenium in inorganic form (Na2SeO3) on the growth and some chosen hematological and biochemical parameters. Two experiments were conducted. During the first one, the effect of selenium in organic form bound to Chlorella algae and selenium in inorganic form was observed when offered gravid sheep against a control group without selenium. During the second one, the effects of selenium in inorganic form and in various organic forms were monitored when offered the sheep after their delivery. The experiments proved positive impact of selenium offered the sheep already during the period of their gravidity (whether in organic or inorganic form) on the growth of the lambs and some chosen biochemical blood parameters of theirs. Selenium in organic form bound to Chlorella, the fluvial algae, had more positive effects on the lambs´ growth parameters than organic form bound to yeast and than inorganic form (Na2SeO3). The effect of selenium in organic form bound to yeast offered the sheep after their delivery was not better than offering inorganic sodium selenite. Lambs´ growth parameters seem to be better when the sheep are offered selenium already during their gravidity in comparison with the sheep having already delivered. The pure Chlorella added into the feeding ration for gravid sheep has a positive impact on lambs´ birth weight and growth parameters. The need appears to reconsider alcaline phosphatase values which the literature states as objective.
Determination of selenium and manganese in cerebrospinal fluid by atomic absorption spectrometry
Jiráková, Lucie ; Kotaška, Karel (advisor) ; Klapková, Eva (referee)
The aim of this study was to confirm the use of electrothermal atomic absorption spectrometry for the determination of selenium and manganese in the cerebrospinal fluid and to investigate concentrations of selenium and manganese in selected group of patients. For selenium was determined the detection limit 2,9 μg/l, for manganese 0,26 μg/l. 73 patients were examined (31 women, 42 men) whose average age was 14,1 years. The patients were divided into two groups according to age (56 children, 17 adults) and into two subgroups according to diagnoses (oncological, neurological). The control group consists of 18 subjects (5 women, 13 men, average age 21,7 years) with non-oncological and non-neurological diagnoses. We found significantly increased selenium concentrations in cerebrospinal fluid in the control group, compared with the group with neurological diagnoses (median = 14,4 μg/l vs. 12,4 μg/l, p < 0.05). Elevated levels of manganese in cerebrospinal fluid was observed in a group of children with oncological diseases compared with control group (1,2 μg/l vs. 0,5 μg/l, p < 0.05). Determination of selenium and manganese in the cerebrospinal fluid may have diagnostic importance in selected groups of patients. Powered by TCPDF (www.tcpdf.org)
Comparison of selenium extraction efficiency from food supplements
Molnárová, Lucia ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The aim of this bachelor thesis was comparison of selenium extraction efficiency from food supplements which contain various declared forms of selenium. The method of atomic absorption spectrometry with flame atomization was used to determine the efficiency of the extraction. The first step for the determination of selenium in four real samples was the experimental finding of optimal conditions for selenium determination by flame AAS technique. Optimized parameters included the flame composition, the fuel flow rate, the angle of burner rotation, the horizontal burner position and the spectral range. During the testing the flame composition, higher responses were measured by using air as an oxidant, and therefore acetylene-air flame was used to other optimize and measure real samples. After optimization of the conditions, the calibration dependence was determined and the basic characteristics of the measurements were calculated. The detection limit and determination repeatability, sensitivity and operating range were determined for selenium determination. The detection limit was 0.12 mg dm-3 . The real samples of the food supplement tablets were mechanically homogenized and transferred to aqueous solutions, which were subsequently analyzed by the optimal conditions. The highest extraction efficiency...
The selenium effect on secondary metabolites production in in vitro cultures of medicinal plants - II
Ošťádalová, Tereza ; Tůmová, Lenka (advisor) ; Kašparová, Marie (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy Candidate: Tereza Ošťádalová Supervisor: Doc. PharmDr. Lenka Tůmová, CSc. Title of diploma thesis: The selenium effect on secondary metabolites production in in vitro cultures of medicinal plants - II. Key words: callus, suspension culture, abiotic elicitor, selenium, Fagopyrum In vitro plant cultures usually produce only a small amount of secondary metabolites. The method of elicitation is one of the options how to increase the production of these substances. The effect of selenium as abiotic elicitor on rutin production in callus and suspension culture of Fagopyrum esculentum Moench., variety Pyra was observed in this study. The release of rutin into the nutrient medium was studied as well. The cultivation was performed in Murashige and Skoog (MS) nutrient medium which was enriched with 1 mg/l of 2,4-dichlorophenoxyacetic acid. The solution of selenium in three different concentrations (c1 = 9.012.10-3 mol/l, c2 = 9.012.10-4 mol/l, c3 = 9.012.10-5 mol/l) was used. The samples were taken after 6, 12, 24, 48, 72 and 168 hours of elicitor treatment. The rutin content was determined by high-performance liquid chromatography (HPLC). The elicitation led to increasing of rutin amount in callus and also in suspension...

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