structural and mechanical parameters
Dotaz
Zobrazit nápovědu
BACKGROUND: Several raw materials and additives are used in meat production. In terms of origin, proteins which are the closest related to meat are derived from slaughtered carcasses. The aim of the work was to assess the effect of their addition on the microstructure, texture and colour of frankfurter-type meat products. RESULTS: Calleja staining, instrumental textural analysis and colour analysis were applied. The microscopic results were evaluated qualitatively. Canonical component and Tukey's HSD were used for textural and RGB evaluation. Microscopically, protein matrix formation in products containing pork haemoglobin (155_16) and pork plasma P (158_16) was found to be different from that in other samples. Texture analysis revealed differences (P < 0.05) in shear force between pork haemoglobin 155_16 and all tested samples, in the hardness between the control (154_16) and pork collagen protein (157_16) and between 157_16 and 160_16. Chewiness showed differences between control 154_16 and collagen proteins 157_16. Colour analysis showed a difference between pork haemoglobin (155_16) and other products (P < 0.05) by component analysis. CONCLUSION: All tested additives were incorporated into the protein matrix. Therefore, they may be used as additives even for unrecommended meat products. Addition of pork haemoglobin has a significant impact on the colour of the final product. © 2018 Society of Chemical Industry.
- MeSH
- barva MeSH
- chuť MeSH
- heterocyklické sloučeniny tetra- a více cyklické analýza MeSH
- kolagen analýza MeSH
- lidé MeSH
- manipulace s potravinami MeSH
- masné výrobky analýza MeSH
- mechanické jevy MeSH
- potravinářské přísady analýza MeSH
- prasata MeSH
- skot MeSH
- tvrdost MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Neuroplastické děje mohou být založeny na modulaci přenosu signálu na synapsích (např. výdeje transmiteru, aktivity receptorů na postsynaptické membráně, změn účinnosti přenosu v postsynaptickém oddílu) nebo mohou být podmíněny změnami vztahů mezi neurony (např. změnami počtu a druhu synapsí, smyslu zapojení jednotlivých prvků neuronálních okruhů). Výsledné změny se pak mohou nacházet v komunikaci mezi jednotlivými neurony (synaptická úroveň), v činnosti místních neuronálních okruhů (úroveň lokálních okruhů), nebo ve vztazích jednotlivých funkčních mozkových celků (multimodulární úroveň). Podstatou neuroplasticity mohou být změny stavby, prokazatelné morfologickými metodami, což se uplatňuje zejména za vývoje a v reakci na poškození (vznik a zánik neuronů, růst jejich výběžků a trnů, přebudování, případně vytváření nových synapsí). Jemnější metody však prokazují, že změny mohou být i na úrovni molekulární (aktivita enzymů, zejména aktivace proteosyntézy a změny ve tvorbě a výdeji mediátorů a modulátorů, aktivace receptorů, úprava aktivity iontových kanálů). Obě úrovně neuroplastických dějů se promítají do změn funkčních parametrů synaptického přenosu. Projevy plasticity mají proto obdobný základ, bez ohledu na příčinu, která je vyvolala, a na oddíl CNS, ve které probíhají.
Neuroplastic mechanisms are based on a modulation of the signal transmission over synapses (e.g., the transmitter release, activity of postsynaptic receptors, efficiency changes in the transmission in the postsynaptic segment). They can be related to the interneuronal relations changes (e.g., number of certain types of synapses, significance of the wiring of different elements of the neuronal circuits). Resulting changes may occur in the communication between neurons (synaptic level), in the activity of the local neuronal circuits (level of local circuits) or in the relations between individual functional brain systems (multimodular level). Neuroplasticity might be based on structural changes, which can be revealed by morphological methods. Such forms of plasticity are more frequent during the development or as a reaction to injury (proliferation and decease of neurons, formation of their processes and spines, remodeling or formation of synapses). More specific methods have determined that these changes are located at the molecular level (enzyme activity, production and release of transmitters or modulators, receptor activation, modulation of ion channels). Both levels of neuroplastic mechanisms bring about changes of functional parameters of the synaptic transmission. Manifestations of plasticity have probably the same basis, irrespectively of a cause, which triggered them, or the brain region where they were accomplished.
Aims: This work focuses on the morphological and mechanical changes in the wall of the subrenal aorta in ratssuff ering from arterial hypertension and chronic renal failure induced by subtotal nephrectomy (NX).Methods: The quantitative structural parameters were assessed using stereological methods. The mechanicalproperties were determined using uniaxial tensile tests.Results: Morphological results showed no signifi cant diff erences in the wall structure of NX rats ten days followingthe subtotal nephrectomy in comparison with the control animals. Pronounced structural changes appeared tenweeks after the nephrectomy. The area of the profi le of the arterial lumen, the volume fraction of elastin, and theelastin lamellar number in the tunica media were signifi cantly higher in the NX rats than in the control animals. Thevalues of the volume fraction of the smooth muscle cells in the tunica media and the lamellar unit thickness weresignifi cantly lower for the NX animals. Mechanical results showed that both kinds of tissues were characterized by anon-linear response when subjected to the tensile test. The moduli of elasticity of subrenal aortas in control and NXanimals were diff erent only for large deformations: NX samples had higher stiff ness. The cyclic loading resulted in atime-dependent response for both tissue types.Conclusions: The results obtained from the NX rats ten days as well as ten weeks after operation suggested anoutward hypertrophy of the aorta. The subrenal aortas of the NX animals had less strength and were less extensiblethan those of the control animals.
- MeSH
- aorta abdominalis fyziologie patofyziologie patologie MeSH
- biomechanika MeSH
- cévní endotel anatomie a histologie patofyziologie MeSH
- chronické selhání ledvin MeSH
- experimenty na zvířatech MeSH
- financování organizované MeSH
- histologie MeSH
- hypertrofie patofyziologie MeSH
- mechanické jevy MeSH
- mikroskopie metody využití MeSH
- nefrektomie metody využití MeSH
- potkani Wistar anatomie a histologie chirurgie MeSH
- renovaskulární hypertenze komplikace patofyziologie MeSH
- statistika jako téma MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
Horns are permanent structures projecting from the head of bovids, consisting of a bony horncore covered with a layer of skin and then a sheath of keratinous material showing variability of growth intensity based on nutrition. From the point of view of the horn's mechanical properties, the keratin sheath has been widely studied, but only a few studies have considered the complete structure of the horn and fewer studies have focused on the bony horncore and its characteristics. The latter showed the important role of the bony core, when cranial appendages are subject to mechanical stress (as happens during fighting). The mechanical properties of bone material, along with its mineral profile, are also important, because they can show effects of different factors, such as nutrition and mineral deficiencies in diet. For this reason, eight horncores of captive common eland male were sampled at four positions along the vertical axis of the horn. The main aim was to study variation in mechanical properties and the mineral content along the vertical axis of the horncores. We further analysed whether the spiral bony ridge present on eland horncores differs in any of the studied properties from adjacent parts of the horncore. In other antelopes, spiral ridges on the horns have been proposed to increase grip during wrestling between males. Cross-sections of the horncores were performed at four positions along the longitudinal axis and, for each position, two bone bars were extracted to be tested in impact and bending. Moreover, in the first sampling position (the closest position to the base) two bars were extracted from the spiralled bony area. The resulting fragments were used to measure ash content, bone density and mineral content. Results showed that horn bone decreased along the vertical axis, in ash (-36%), density (-32%), and in impact work 'U' (marginally significant but large effect: -48%). The concentration of several minerals decreased significantly (Mg, Cr, Mn and Tl by -33%, -25%, -31%, -43%, respectively) between the basal and the uppermost sampling site. The bone tissue of the horncore spiral compared with non-spiral bone of the same position showed a lower ash content (53% vs. 57%), Mg and Mn; in addition to showing approximately half values in work to peak force 'W', bending strength 'BS' and 'U', but not in Young's modulus of elasticity 'E'. In conclusion, similarly to the results in a totally different fighting bony structure, the antlers, the horncore of eland shows advantageous parameters in bone tissue of the base in respect to the tip, with higher values for mechanical properties, density and mineral profile. Moreover, the spiral bone tissue showed lower material mechanical properties. Probably the spiral tissue of the horn may have a role in deflecting potential cross-sectional fractures during wrestling. In addition, it may serve to improve the grip during wrestling, and we propose that it may also prevent risk of rotation of sheath with respect to internal bone not only in this, but also in other straight bovid horns.
- MeSH
- mechanický stres MeSH
- parohy anatomie a histologie chemie fyziologie MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Non-invasive optical diagnostic methods allow important information about studied systems to be obtained in a non-destructive way. Complete diagnosis requires information about the chemical composition as well as the morphological structure of a sample. We report on the development of an opto-mechanical probe that combines Raman spectroscopy (RS) and optical coherence tomography (OCT), two methods that provide all the crucial information needed for a non-invasive diagnosis. The aim of this paper is to introduce the technical design, construction and optimization of a dual opto-mechanical probe combining two in-house developed devices for confocal RS and OCT. The unique benefit of the probe is a gradual acquisition of OCT and RS data, which allows to use the acquired OCT images to pinpoint locations of interest for RS measurements. The parameters and the correct functioning of the probe were verified by RS scanning of various samples (silicon wafer and ex vivo tissue) based on their OCT images - lateral as well as depth scanning was performed. Both the OCT and RS systems were developed, optimized and tested with the ultimate aim of verifying the functionality of the probe. Picture: Schematic illustration and visualization of the developed RS-OCT probe.
Guanine quadruplex (GQ) is a noncanonical nucleic acid structure formed by guanine-rich DNA and RNA sequences. Folding of GQs is a complex process, where several aspects remain elusive, despite being important for understanding structure formation and biological functions of GQs. Pulling experiments are a common tool for acquiring insights into the folding landscape of GQs. Herein, we applied a computational pulling strategy─steered molecular dynamics (SMD) simulations─in combination with standard molecular dynamics (MD) simulations to explore the unfolding landscapes of tetrameric parallel GQs. We identified anisotropic properties of elastic conformational changes, unfolding transitions, and GQ mechanical stabilities. Using a special set of structural parameters, we found that the vertical component of pulling force (perpendicular to the average G-quartet plane) plays a significant role in disrupting GQ structures and weakening their mechanical stabilities. We demonstrated that the magnitude of the vertical force component depends on the pulling anchor positions and the number of G-quartets. Typical unfolding transitions for tetrameric parallel GQs involve base unzipping, opening of the G-stem, strand slippage, and rotation to cross-like structures. The unzipping was detected as the first and dominant unfolding event, and it usually started at the 3'-end. Furthermore, results from both SMD and standard MD simulations indicate that partial spiral conformations serve as a transient ensemble during the (un)folding of GQs.
There is a long history of mathematical and computational modelling with the objective of understanding the mechanisms governing cartilage׳s remarkable mechanical performance. Nonetheless, despite sophisticated modelling development, simulations of cartilage have consistently lagged behind structural knowledge and thus the relationship between structure and function in cartilage is not fully understood. However, in the most recent generation of studies, there is an emerging confluence between our structural knowledge and the structure represented in cartilage modelling. This raises the prospect of further refinement in our understanding of cartilage function and also the initiation of an engineering-level understanding for how structural degradation and ageing relates to cartilage dysfunction and pathology, as well as informing the potential design of prospective interventions. Aimed at researchers entering the field of cartilage modelling, we thus review the basic principles of cartilage models, discussing the underlying physics and assumptions in relatively simple settings, whilst presenting the derivation of relatively parsimonious multiphase cartilage models consistent with our discussions. We proceed to consider modern developments that start aligning the structure captured in the models with observed complexities. This emphasises the challenges associated with constitutive relations, boundary conditions, parameter estimation and validation in cartilage modelling programmes. Consequently, we further detail how both experimental interrogations and modelling developments can be utilised to investigate and reduce such difficulties before summarising how cartilage modelling initiatives may improve our understanding of cartilage ageing, pathology and intervention.
- MeSH
- biologické modely * MeSH
- biomechanika MeSH
- chrupavka patologie fyziologie MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
The acid dissociation (ionization) constant pK(a) is one of the fundamental properties of organic molecules. We have evaluated different computational strategies and models to predict the pK(a) values of substituted phenols using partial atomic charges. Partial atomic charges for 124 phenol molecules were calculated using 83 approaches containing seven theory levels (MP2, HF, B3LYP, BLYP, BP86, AM1, and PM3), three basis sets (6-31G*, 6-311G, STO-3G), and five population analyses (MPA, NPA, Hirshfeld, MK, and Löwdin). The correlations between pK(a) and various atomic charge descriptors were examined, and the best descriptors were selected for preparing the quantitative structure-property relationship (QSPR) models. One QSPR model was created for each of the 83 approaches to charge calculation, and then the accuracy of all these models was analyzed and compared. The pK(a)s predicted by most of the models correlate strongly with experimental pK(a) values. For example, more than 25% of the models have correlation coefficients (R²) greater than 0.95 and root-mean-square errors smaller than 0.49. All seven examined theory levels are applicable for pK(a) prediction from charges. The best results were obtained for the MP2 and HF level of theory. The most suitable basis set was found to be 6-31G*. The 6-311G basis set provided slightly weaker correlations, and unexpectedly also, the STO-3G basis set is applicable for the QSPR modeling of pK(a). The Mulliken, natural, and Löwdin population analyses provide accurate models for all tested theory levels and basis sets. The results provided by the Hirshfeld population analysis were also acceptable, but the QSPR models based on MK charges show only weak correlations.
- MeSH
- chemické modely MeSH
- farmaceutická chemie metody statistika a číselné údaje MeSH
- fenoly analýza chemie MeSH
- kinetika MeSH
- kvantitativní vztahy mezi strukturou a aktivitou MeSH
- kvantová teorie MeSH
- léčivé přípravky analýza chemie MeSH
- molekulární konformace MeSH
- počítačová simulace MeSH
- statická elektřina MeSH
- statistické modely MeSH
- Publikační typ
- časopisecké články MeSH
A set of new substituted dienes were synthesized from betulinic acid by its oxidation to 30-oxobetulinic acid followed by the Wittig reaction. Cytotoxicity of all compounds was tested in vitro in eight cancer cell lines and two noncancer fibroblasts. Almost all dienes were more cytotoxic than betulinic acid. Compounds 4.22, 4.30, 4.33, 4.39 had IC50 below 5 μmol/L; 4.22 and 4.39 were selected for studies of the mechanism of action. Cell cycle analysis revealed an increase in the number of apoptotic cells at 5 × IC50 concentration, where activation of irreversible changes leading to cell death can be expected. Both 4.22 and 4.39 led to the accumulation of cells in the G0/G1 phase with partial inhibition of DNA/RNA synthesis at 1 × IC50 and almost complete inhibition at 5 × IC50. Interestingly, compound 4.39 at 5 × IC50 caused the accumulation of cells in the S phase. Higher concentrations of tested drugs probably inhibit more off-targets than lower concentrations. Mechanisms disrupting cellular metabolism can induce the accumulation of cells in the S phase. Both compounds 4.22 and 4.39 trigger selective apoptosis in cancer cells via intrinsic pathway, which we have demonstrated by changes in the expression of the crucial apoptosis-related protein. Pharmacological parameters of derivative 4.22 were superior to 4.39, therefore 4.22 was the finally selected candidate for the development of anticancer drug.
- MeSH
- alkadieny chemická syntéza chemie farmakologie MeSH
- apoptóza účinky léků MeSH
- buněčný cyklus účinky léků MeSH
- kultivované buňky MeSH
- lidé MeSH
- molekulární struktura MeSH
- pentacyklické triterpeny chemie farmakologie MeSH
- proliferace buněk účinky léků MeSH
- protinádorové látky chemická syntéza chemie farmakologie MeSH
- psi MeSH
- screeningové testy protinádorových léčiv MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- psi MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVE: The mechanical properties and microstructure of the perineal body are important for the improvement of numerical models of pelvic organs. We determined the mechanical parameters and volume fractions of the ewe perineal body as an animal model. METHODS: The 39 specimens of 13 pregnant swifter ewes delivering by cesarean section (aged 2 years, weight 61.2 ± 6.2 kg (mean ± standard deviation) and 24 specimens of 8 postmenopausal swifter ewes 150 days after surgical ovariectomy (aged 7 years, 58.6 ± 4.6 kg)) were loaded uniaxially to determine Young's moduli of elasticity in the small (E0) and large (E1) deformation regions, and ultimate stresses and strains. The 63 adjacent tissue samples were processed histologically to assess volume fractions of smooth and skeletal muscle, adipose cells, elastin, and type I collagen using a stereological point testing grid. We compared the structural and mechanical differences along the ewe perineal body, and between pregnant and postmenopausal groups. RESULTS: The pregnant/postmenopausal perineal body was composed of smooth muscle (12/14%; median), skeletal muscle (12/16%), collagen (10/23%), elastin (8/7%), and adipose cells (6/6%). The E0 was 37/11 kPa (median), E1 was 0.97/1.04 MPa, ultimate stress was 0.55/0.59 MPa, and ultimate strain was 0.90/0.87 for pregnant/postmenopausal perineal body. The perineal body showed a structural and mechanical stability across the sites. The pregnant ewes had a higher amount of skeletal muscle, higher E0, and a less amount of collagen when compared with postmenopausal ewes. CONCLUSIONS: The data can be used as input for models simulating vaginal delivery, pelvic floor prolapsed, or dysfunction.
- MeSH
- biomechanika MeSH
- elastin analýza MeSH
- hladké svalstvo anatomie a histologie fyziologie MeSH
- kolagen analýza MeSH
- kosterní svaly anatomie a histologie fyziologie MeSH
- modely u zvířat MeSH
- ovce MeSH
- perineum anatomie a histologie fyziologie MeSH
- postmenopauza MeSH
- těhotenství MeSH
- tukové buňky MeSH
- zvířata MeSH
- Check Tag
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
