peak strain Dotaz Zobrazit nápovědu
- MeSH
- biologické modely MeSH
- inbrední kmeny myší genetika metabolismus MeSH
- kostní denzita genetika MeSH
- myši MeSH
- osteoporóza genetika MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
Biomechanics-based assessment of Abdominal Aortic Aneurysm (AAA) rupture risk has gained considerable scientific and clinical momentum. However, computation of peak wall stress (PWS) using state-of-the-art finite element models is time demanding. This study investigates which features of the constitutive description of AAA wall are decisive for achieving acceptable stress predictions in it. Influence of five different isotropic constitutive descriptions of AAA wall is tested; models reflect realistic non-linear, artificially stiff non-linear, or artificially stiff pseudo-linear constitutive descriptions of AAA wall. Influence of the AAA wall model is tested on idealized (n=4) and patient-specific (n=16) AAA geometries. Wall stress computations consider a (hypothetical) load-free configuration and include residual stresses homogenizing the stresses across the wall. Wall stress differences amongst the different descriptions were statistically analyzed. When the qualitatively similar non-linear response of the AAA wall with low initial stiffness and subsequent strain stiffening was taken into consideration, wall stress (and PWS) predictions did not change significantly. Keeping this non-linear feature when using an artificially stiff wall can save up to 30% of the computational time, without significant change in PWS. In contrast, a stiff pseudo-linear elastic model may underestimate the PWS and is not reliable for AAA wall stress computations.
INTRODUCTION: We aimed to compare the acute differences in left ventricular (LV) function and mechanical synchrony during nonselective His bundle pacing (ns-HBP) versus selective His bundle pacing (s-HBP) using strain echocardiography. METHODS AND RESULTS: Consecutive patients with permanent His bundle pacing, in whom it was possible to obtain both s-HBP and ns-HBP, were studied in two centers. In each patient, echocardiography was performed sequentially during s-HBP and ns-HBP. Speckle-tracking echocardiography parameters were analyzed: Global longitudinal strain (GLS), the time delay between peak systolic strain in the basal septal and basal lateral segments (BS-BL delay), peak strain dispersion (PSD) and strain delay index. Right ventricle function was assessed using tricuspid annular plane systolic excursion (TAPSE) and tissue Doppler velocity of the lateral tricuspid annulus (S'). A total of 69 patients (age: 75.6 ± 10.5 years; males: 75%) were enrolled. There were no differences in LV ejection fraction and GLS between s-HBP and ns-HBP modes: 59% versus 60%, and -15.6% versus -15.7%, respectively; as well as no difference in BS-BL delay and strain delay index. The PSD value was higher in the ns-HBP group than in the s-HBP group with the most pronounced difference in the basal LV segments. No differences in right ventricular function parameters (TAPSE and S') were found. CONCLUSION: The ns-HBP and s-HBP modes seem comparable regarding ventricular function. The dyssynchrony parameters were significantly higher during ns-HBP, however, the difference seems modest and clarification of its impact on LV function requires a larger long-term study.
We investigated the utility of strain, strain rate, and tissue Doppler imaging (TDI) for the evaluation of the right ventricle (RV) impairment in patients with a hypertrophic obstructive cardiomyopathy (HOCM) who underwent a successful alcohol septal ablation (ASA) and were without RV hypertrophy. A group of 19 patients suffering from HOCM with 22 controls was compared. The parameters of TDI were evaluated in mitral and tricuspid annulus. Strain and strain rate derived from TDI were assessed in an apical free wall of RV, as well as in basal segments of the left ventricle. Between both groups, there were significant differences only in isovolumic pre-ejection time (79.2±17.3 ms vs. 58.5±8.1 ms, p<0.01), isovolumic relaxation time (104.7±26.2 ms vs. 77.3±24.5 ms, p<0.01), myocardial performance (Tei) index measured from TDI (0.61±0.14 vs. 0.49±0.09, p<0.01), and early peak diastolic velocity of TDI (10.6±1.67 cm/s vs. 12.6±2.21 cm/s; p<0.05). Our results suggest the impairment of both systolic and diastolic RV function in patients suffering from HOCM. TDI-related parameters appear to be more sensitive than strain and strain rate for evaluation.
- MeSH
- diastola fyziologie MeSH
- dopplerovská echokardiografie MeSH
- financování organizované MeSH
- funkce pravé komory srdeční fyziologie MeSH
- hypertrofická kardiomyopatie patofyziologie ultrasonografie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mitrální chlopeň fyziologie MeSH
- senioři MeSH
- systola fyziologie MeSH
- tepový objem fyziologie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
Halophilic archaea are one of the microorganism groups that have adapted to living in high saline environments and are important in terms of their potential use in biotechnology industry. One of the most important compounds they have, carotenoid, is used in food, cosmetics, and medical industries. The selected strain was identified as an extremely halophilic and thermophilic archaeon, Haloterrigena thermotolerans K15, based on morphological, biochemical, and physiological evidence as well as 16S rRNA analysis and screened by a scanning electron microscope and an atomic force microscope for the first time. The carotenoid contents of H. thermotolerans K15 isolated from Salt Lake (Tuz Gölü, Turkey) were determined by RP-HPLC-DAD and their isomers were characterized according to UV-Vis spectra by cis peak intensity and spectral fine structure. In addition to all-trans bacterioruberin as a major carotenoid, many isomers of the bacterioruberin such as monoanhydrobacterioruberin and bisanhydrobacterioruberin were also found. The antioxidant activity of carotenoid extract from H. thermotolerans was analyzed by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging method. The carotenoid extract showed antioxidant activity statistically significantly higher than ascorbic acid and butylated hydroxytoluene as reference compounds (p < 0.05). This is the first study about carotenoid characterization and antioxidant activity of H. thermotolerans K15. The obtained results suggest the potential use of H. thermotolerans K15 products as a substitute for synthesized chemical carotenoids and antioxidants.
- MeSH
- antioxidancia * MeSH
- Halobacteriaceae * genetika MeSH
- karotenoidy MeSH
- RNA ribozomální 16S genetika MeSH
- Publikační typ
- časopisecké články MeSH
AIM OF THE STUDY: To assess the diagnostic utility of a simplified approach to relative apical sparing of longitudinal strain (RAS LS) using only an apical four-chamber view (A4C) in patients with AL amyloid cardiomyopathy (ALAC). METHODS: We retrospectively evaluated echocardiographic recordings of 20 patients with ALAC, 20 patients with Fabry disease-related cardiomyopathy (FD), and 20 patients with concentric hypertensive left ventricular hypertrophy (HLVH) matched for mean LV mean thickness. Peak segmental LS values of the interventricular septum and lateral LV wall were measured in the A4C using two-dimensional speckle-tracking echocardiography. RAS LS was calculated as average apical LS/(average basal LS + average midventricular LS). RESULTS: Relative apical sparing of longitudinal strain values in patients with ALAC (1.23 ± 0.64) were significantly higher than those in FD patients (0.75 ± 0.19, P < 0.05) as well as in individuals with HLVH (0.75 ± 0.23, P < 0.05), but with a significant overlap. The optimal RAS LS value differentiating ALAC from FD and HLVH with 70% sensitivity and 75% specificity was 0.88 (AUC 0.79). In multivariate modeling, RAS LS was significantly additive to traditional predictors of ALAC (low QRS voltage and pseudoinfarct ECG patterns, pericardial effusion, E/e' ratio, E-wave deceleration time; P < 0.05 for all models). CONCLUSIONS: Simplified RAS LS evaluation represents an attractive approach for diagnostics of ALAC. However, because of considerable overlap with other disorders with hypertrophic phenotype, the analysis of RAS LS in the A4C should be combined with other traditional echocardiographic and ECG predictors in differentiating ALAC from other forms of concentric LV wall thickening.
- MeSH
- amyloidóza diagnostické zobrazování patofyziologie MeSH
- echokardiografie metody MeSH
- kardiomyopatie diagnostické zobrazování patofyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- reprodukovatelnost výsledků MeSH
- retrospektivní studie MeSH
- senzitivita a specificita MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Membrane diafiltration was used for separation of the extracellular complex of chitinolytic enzymes of C. paraputrificum J4 free from contaminants with molar mass higher than 100 kDa and lower than 30 kDa. The enzyme complex containing beta-N-acetylglucosaminidase (NAGase) and six endochitinases was concentrated on a membrane with cut-off 30 kDa. In this retentate, the NAGase/endochitinase specific activity was 13.5/6.5-times higher than in the initial culture filtrate. The proportion (in%) of endochitinases: 23 (90 kDa), 42 (86 kDa), 8 (72 kDa), 16 (68 kDa) and 8 (60 kDa) was calculated from their peak areas (determined by densitometry) in images of zymograms. NAGase (38 kDa) was less active and stable at pH lower than 4 and higher than 8 but it was more temperature-stable than endochitinases, especially at 40-60 degrees C. In contrast to endochitinases, the pH optimum of NAGase activity was shifted by ca. 0.7 pH units to the alkaline region. Extracellular NAGase together with six endochitinases secreted by C. paraputrificum J4 were separated by membrane diafiltration and characterized by molar mass, stability and activity in dependence on pH and temperature. The knowledge of composition of chitinolytic enzymes, their pH and temperature stability is useful for optimization of the separation process.
- MeSH
- acetylglukosaminidasa chemie izolace a purifikace metabolismus MeSH
- bakteriální proteiny chemie izolace a purifikace metabolismus MeSH
- chitin metabolismus MeSH
- chitinasy chemie izolace a purifikace metabolismus MeSH
- Clostridium enzymologie MeSH
- financování organizované MeSH
- koncentrace vodíkových iontů MeSH
- lidé MeSH
- molekulová hmotnost MeSH
- stabilita enzymů MeSH
- teplota MeSH
- ultrafiltrace metody MeSH
- Check Tag
- lidé MeSH
RATIONALE: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling of bacteria is often used to distinguish isolates beyond the species level, even to the level of individual strains. However, the influence of bacterial growth conditions on the discriminatory power of the method to the strain level has not yet been properly evaluated. METHODS: For the purpose of this study, we used an extraction protocol recommended for clinical laboratories for MALDI-TOF MS profiling of bacteria. Seventeen closely related strains of the Lactobacillus acidophilus group were cultivated under various growth conditions (growth medium, time, and temperature) and analyzed. RESULTS: Out of a total of 327 samples, 80 % were correctly assigned to the species level and 13 % only to the genus level. When using data obtained from strains cultured for lengthy periods (7 days), the identification success rate was reduced due to poor signal quality, whereas with shorter cultivation times there was no influence of growth conditions on the assignment of particular strains to their corresponding species. However, variations in certain cultivation parameters were found to influence identification and differentiation of most of the examined strains. Strain discrimination was frequently found to be dependent on the selection of culture conditions. MALDI-TOF MS data treatment (strain-specific peak detection, BioTyper scoring, subtyping, or cluster analysis) also contributed to the discriminatory power of the method. CONCLUSIONS: When MALDI-TOF MS profiling of bacteria is used for strain discrimination, the cultivation conditions should be properly optimized and controlled as they significantly contribute to the discriminatory power of the method.
- MeSH
- čas MeSH
- fylogeneze MeSH
- kultivační média MeSH
- Lactobacillus acidophilus klasifikace genetika růst a vývoj izolace a purifikace MeSH
- reprodukovatelnost výsledků MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- techniky typizace bakterií * metody normy MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
RATIONALE: Distinguishing between individual bacterial strains below the species level is a challenge to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial profiling. We propose a quick method for improving strain differentiation of two Staphylococcus and one Bacillus species. METHODS: An alternative procedure to the extraction protocol recommended by Bruker Daltonics was developed. Ethanol-sterilized cells of six S. aureus and six S. haemolyticus strains were digested by trypsin using 2-min microwave irradiation and were then analyzed. Twenty-eight strains belonging to two ecotypes of B. subtilis were subjected to the same procedure to extend the scope of the method. RESULTS: S. aureus and S. haemolyticus strains, only partially distinguishable by the standard sample preparation procedure, were subjected to microwave-assisted tryptic digestion. The repeatability of the procedure was checked in three experiments accomplished at weekly intervals. Clear distinction of the strains was achieved by cluster analysis. The differentiation of B. subtilis ecotypes was also improved significantly by the digestion method. The discriminatory power of the novel method was supported by an increase in the number of strain-specific peaks, as compared to the standard method. CONCLUSIONS: The method modulates the discriminatory power of MALDI-TOF MS profiling. The differentiation of a set of S. aureus, S. haemolyticus and B. subtilis strains was improved significantly after microwave-accelerated tryptic digestion of the cellular material.
- MeSH
- Bacillus chemie klasifikace MeSH
- mikrovlny MeSH
- molekulární typizace metody MeSH
- shluková analýza MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice metody MeSH
- Staphylococcus chemie klasifikace MeSH
- trypsin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
