Interactions between hyaluronan and the antimicrobial peptide cecropin B were studied in water and PBS using high-resolution ultrasonic spectroscopy and isothermal titration calorimetry. Although each technique is fundamentally different, they both gave identical results. It was found that the molecular weight of hyaluronan plays an important role in the interactions - in particular, the transition between the rod conformation and the random coil conformation. In water, interactions were saturated in a molar charge ratio of 1.5 and not 1.0 as expected. The later saturation of the interaction probably occurred either for steric reasons or due to the interaction between functional groups in the cecropin structure, which allowed complete dissociation of the antimicrobial peptide. In PBS, in contrast to water, no interactions were observed, irrespective of the molecular weight of hyaluronan. Thus, at a sufficiently high ionic strength, the interactions were suppressed.

• Klíčová slova
• Cecropin B, High-resolution ultrasonic spectroscopy, Hyaluronan, Interaction, Isothermal titration calorimetry,
• MeSH
• cekropiny * MeSH
• kalorimetrie metody   MeSH
• kyselina hyaluronová * MeSH
• reologie MeSH
• termodynamika MeSH
• voda chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cekropiny * MeSH
• kyselina hyaluronová * MeSH
• voda MeSH

Studies of protein unfolding mechanisms are critical for understanding protein functions inside cells, de novo protein design as well as defining the role of protein misfolding in neurodegenerative disorders. Calorimetry has proven indispensable in this regard for recording full energetic profiles of protein unfolding and permitting data fitting based on unfolding pathway models. While both kinetic and thermodynamic protein stability are analysed by varying scan rates and reheating, the latter is rarely used in curve-fitting, leading to a significant loss of information from experiments. To extract this information, we propose fitting both first and second scans simultaneously. Four most common single-peak transition models are considered: (i) fully reversible, (ii) fully irreversible, (iii) partially reversible transitions, and (iv) general three-state models. The method is validated using calorimetry data for chicken egg lysozyme, mutated Protein A, three wild-types of haloalkane dehalogenases, and a mutant stabilized by protein engineering. We show that modelling of reheating increases the precision of determination of unfolding mechanisms, free energies, temperatures, and heat capacity differences. Moreover, this modelling indicates whether alternative refolding pathways might occur upon cooling. The Matlab-based data fitting software tool and its user guide are provided as a supplement.

• MeSH
• kalorimetrie metody   MeSH
• kinetika MeSH
• kuřecí embryo MeSH
• muramidasa chemie   metabolismus   MeSH
• proteinové inženýrství MeSH
• rozbalení proteinů MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• muramidasa MeSH

This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO3)2, ZnCl2, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).

• Klíčová slova
• Portland cement, ground blast furnace slag, isoperibolic calorimetry, isothermal calorimetry, zinc,
• Publikační typ
• časopisecké články MeSH

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. Zinc is one of these elements. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO3)2 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05%, 0.1%, 0.5% and 1% of cement weight. The effect of zinc on hydration was monitored by isothermal and isoperibolic calorimetry. A 15% addition of fly ash to cement mainly causes further retardation of hydration reactions due to the reactions of fly ash particles with Ca2+ ions from cement. The strongest effect on the hydration retardation from all investigated compounds showed in ZnO as it dissolves very slowly. On the contrary, for the dosage of 1% of zinc in the form of ZnCl2 significant acceleration of hydration occurred. In this work, a synergistic effect on the prolongation of hydration with a combination of cement, zinc and fly ash was demonstrated. The lengths of induction periods were assessed from detected calorimetric curves and from these lengths the curves were gained by fitting with the exponential function. Final products were next analyzed using X-ray diffraction.

• Klíčová slova
• fly ash, isoperibolic calorimetry, isothermal calorimetry, portland cement, zinc,
• Publikační typ
• časopisecké články MeSH

• Klíčová slova
• EXERTION *, METABOLISM *,
• MeSH
• kalorimetrie * MeSH
• lidé MeSH
• metabolismus * MeSH
• potřeby pro domácnost * MeSH
• práce * MeSH
• tělesná námaha * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

To assess BAT activity in humans at a population level, infrared thermography (IRT) represents a safe, readily repeatable and affordable alternative to 18F-FDG-PET. Building upon a previously proposed method by our laboratory, we further refined the image computational algorithm to quantify BAT activation in the cervical-supraclavicular (C-SCV) region of healthy young men under thermo-neutral and cold exposure conditions. Additionally, we validated the whole-body calorimeter (WBC) in reliably measuring cold-induced thermogenesis. The temperature gradient between C-SCV-deltoid regions, and the corresponding difference in heat power output, increased upon cold air exposure relative to thermo-neutral conditions (by 74.88 %, p<0.0001; and by 71.34 %, p<0.0001 respectively). Resting and cumulative energy expenditure (EE) rose significantly (by 13.14 % and 9.12 % respectively, p=0.0001) while positive correlations between IRT measures and EE were found with cold air exposure (percentage change in heat power gradient between ROI and deltoid, cold air: r(2)=0.29, p=0.026, Pearson's correlation). IRT and WBC can be used to study BAT activation. The refined algorithm allows for more automation and objectivity in IRT data analysis, especially under cold air exposures.

• MeSH
• dospělí MeSH
• hnědá tuková tkáň metabolismus   MeSH
• lidé MeSH
• mladý dospělý MeSH
• nepřímá kalorimetrie MeSH
• termogeneze * MeSH
• termografie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

OGTT prolonged to 4 hours was performed in untreated 50 obese outpatients (mean age 37.9 years and BMI 37.2). Parallel to glucose, insulin, growth hormone (GH), cortisol, beta-hydroxybutyrate (BOHB), nonesterified fatty acids (NEFA) and indirect calorimetry (RQ) were estimated at hourly intervals. Basal values of thyroxine (T4), triiodothyronine (T3), total cholesterol and triacylglycerols were also obtained. Mean glycemia after overnight fasting as well as after 75 g glucose reached upper limits of the normal range. The subsequent decrease was slower. Insulinemia followed a similar trend. The initial drop of GH after the glucose load reverted to an increase above the basal value. A similar pattern was observed with cortisolemia, but the decrease and increase were less important. The basal value of RQ was rather low and glucose ingestion produced only a small increase, followed by a greater decrease. Serum levels of NEFA and BOHB sharply decreased one hour after glucose intake and afterwards regained the initial values. The mean basal values of T4 and T3 were within the normal range--the low T3 syndrome was not involved in the large majority of cases. Cholesterol and triacylglycerols approached the upper normal limit. The correlations brought additional information. Insulinemia increased parallel with the amount of body fat. The basal level was decisive for most hormones and substrates--the high or low set level could be followed in the course of the whole test. Increased insulinemia and increased glycemia suggested the presence of a mild insulin resistance with the participation of GH and cortisol. Increased levels of fasting insulinemia and glycemia were present also in obese subjects with a normal OGTT. The correlations permitted to disclose insulin-like effects of GH on basal conditions. Increased BOHB was responsible for a high cholesterol. It is suggested that even small fluctuations of glycemia related to food intake may produce a substantial modification of the hormonal status in obese subjects and initiate or support the metabolic disorders in obesity. In this respect a greater role is ascribed to the phase of decreasing glycemia in comparison to the increasing phase. Lipids are the prevailing source of energy in insulin resistant subjects. The rather stable values of indirect calorimetry indicate that energy metabolism of obese subject works on a low, pre-set level-independently on the supply of some relevant hormones and substrates.

• MeSH
• dospělí MeSH
• glukózový toleranční test MeSH
• hormony krev   MeSH
• hydroxybutyráty krev   MeSH
• krevní glukóza metabolismus   MeSH
• kyselina 3-hydroxymáselná MeSH
• kyseliny mastné neesterifikované krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nepřímá kalorimetrie MeSH
• obezita patofyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hormony MeSH
• hydroxybutyráty MeSH
• krevní glukóza MeSH
• kyselina 3-hydroxymáselná MeSH
• kyseliny mastné neesterifikované MeSH

• MeSH
• energetický metabolismus * MeSH
• kalorimetrie * MeSH
• lidé MeSH
• nepřímá kalorimetrie * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH

The process of thermal denaturation of a covalently modified form of barley grain nonspecific lipid transfer protein 1b (ns-LTP1b) was investigated by nuclear magnetic resonance (NMR) and differential scanning calorimetry up to 115 degrees C. The denaturation was found to be irreversible and highly cooperative. A method of numerical quantitative analysis allowing us to fit the NMR data to a transition state model without further simplification was developed. On the basis of the obtained values of transition state enthalpy and entropy, the rate of denaturation was calculated as a simple measure of protein stability at various temperatures. The effect of disulfide bond reduction on thermal denaturation of ns-LTP1b was studied and discussed in the context of quality control of barley products during storage and processing.

• MeSH
• denaturace proteinů * MeSH
• diferenciální skenovací kalorimetrie MeSH
• ječmen (rod) chemie   MeSH
• magnetická rezonanční spektroskopie MeSH
• rostlinné proteiny chemie   MeSH
• semena rostlinná chemie   MeSH
• transportní proteiny chemie   MeSH
• vysoká teplota * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• rostlinné proteiny MeSH
• transportní proteiny MeSH

Data derived from indirect calorimetry in patients with stable chronic pneumopathies were evaluated together with their pulmonary function data (spirometry, diffusing capacity, blood gases). Their basal metabolic rate was significantly higher (116.1% of the predicted value), this increase being more expressed in the patients with hypoxemia and with more severe obstructive disorder. In chronic obstructive pulmonary disease, the increased energy expenditure in hypoxemia was accompanied with increased lipid oxidation. There also was a correlation between the patients' nutritional status (evaluated by their body mass index) and their pulmonary function. These results confirm the impairment of pulmonary function in malnourished patients.

• MeSH
• bazální metabolismus MeSH
• chronická nemoc MeSH
• lidé středního věku MeSH
• lidé MeSH
• nepřímá kalorimetrie * MeSH
• obstrukční plicní nemoci patofyziologie   MeSH
• respirační funkční testy * MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH