Synchronizing neural processes, mental activities, and social interactions is considered to be fundamental for the creation of temporal order on the personal and interpersonal level. Several different types of synchronization are distinguished, and for each of them examples are given: self-organized synchronizations on the neural level giving rise to pre-semantically defined time windows of some tens of milliseconds and of approximately 3 s; time windows that are created by synchronizing different neural representations, as for instance in aesthetic appreciations or moral judgments; and synchronization of biological rhythms with geophysical cycles, like the circadian clock with the 24-hr rhythm of day and night. For the latter type of synchronization, an experiment is described that shows the importance of social interactions for sharing or avoiding common time. In a group study with four subjects being completely isolated together for 3 weeks from the external world, social interactions resulted both in intra- and interindividual circadian synchronization and desynchronization. A unique phenomenon in circadian regulation is described, the "beat phenomenon," which has been made visible by the interaction of two circadian rhythms with different frequencies in one body. The separation of the two physiological rhythms was the consequence of social interactions, that is, by the desire of a subject to share and to escape common time during different phases of the long-term experiment. The theoretical arguments on synchronization are summarized with the general statement: "Nothing in cognitive science makes sense except in the light of time windows." The hypothesis is forwarded that time windows that express discrete timing mechanisms in behavioral control and on the level of conscious experiences are the necessary bases to create cognitive order, and it is suggested that time windows are implemented by neural oscillations in different frequency domains.

• Klíčová slova
• beat phenomenon, circadian rhythm, desynchronization, discrete time, social interaction, synchronization, time window,
• MeSH
• biologické modely MeSH
• časové faktory MeSH
• cirkadiánní rytmus fyziologie   MeSH
• interpersonální vztahy * MeSH
• lidé MeSH
• longitudinální studie MeSH
• vnímání času * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH

BACKGROUND: The mechanisms that initiate and sustain persistent atrial fibrillation are not well characterized. Ablation results remain significantly worse than in paroxysmal atrial fibrillation in which the mechanism is better understood and subsequent targeted therapy has been developed. The aim of this study was to characterize and quantify patterns of activation during atrial fibrillation using contact mapping. METHODS: Patients with persistent atrial fibrillation (n=14; mean age, 61±8 years; ejection fraction, 59±10%) underwent simultaneous biatrial contact mapping with 64 electrode catheters. The atrial electrograms were transformed into phase, and subsequent spatiotemporal mapping was performed to identify phase singularities (PSs). RESULTS: PSs were located in both atria, but we observed more PSs in the left atrium compared with the right atrium (779±302, 552±235; P=0.015). Although some PSs of duration sufficient to complete >1 rotation were detected, the maximum PS duration was only 1150 ms, and the vast majority (97%) of PSs persisted for too short a period to complete a full rotation. Although in selected patients there was evidence of PS local clustering, overall, PSs were distributed globally throughout both chambers with no clear anatomic predisposition. In a subset of patients (n=7), analysis was repeated using an alternative established atrial PS mapping technique, which confirmed our initial findings. CONCLUSIONS: No sustained rotors or localized drivers were detected, and instead, the mechanism of arrhythmia maintenance was consistent with the multiple wavelet hypothesis, with passive activation of short-lived rotational activity. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01765075.

• Klíčová slova
• arrhythmias, cardiac, atrial fibrillation, electrodes, heart atria, humans,
• MeSH
• akční potenciály * MeSH
• časové faktory MeSH
• elektrofyziologické techniky kardiologické * MeSH
• fibrilace síní diagnóza   patofyziologie   MeSH
• kardiostimulace umělá MeSH
• lidé středního věku MeSH
• lidé MeSH
• prediktivní hodnota testů MeSH
• senioři MeSH
• srdeční frekvence MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• práce podpořená grantem MeSH

BACKGROUND: Despite all the gains that have been achieved with endovascular mechanical thrombectomy revascularization and intravenous thrombolysis logistics since 2015, there is still a subgroup of patients with salvageable brain tissue for whom persistent emergent large vessel occlusion portends a catastrophic outcome. OBJECTIVE: To test the safety and efficacy of emergent microsurgical intervention in patients with acute ischemic stroke and symptomatic middle cerebral artery occlusion after failure of mechanical thrombectomy. METHODS: A prospective two-center cohort study was conducted. Patients with acute ischemic stroke and middle cerebral artery occlusion for whom recanalization failed at center 1 were randomly allocated to the microsurgical intervention group (MSIG) or control group 1 (CG1). All similar patients at center 2 were included in the control group 2 (CG2) with no surgical intervention. Microsurgical embolectomy and/or extracranial-intracranial bypass was performed in all MSIG patients at center 1. RESULTS: A total of 47 patients were enrolled in the study: 22 at center 1 (12 allocated to the MSIG and 10 to the CG1) and 25 patients at center 2 (CG2). MSIG group patients showed a better clinical outcome on day 90 after the stroke, where a modified Rankin Scale score of 0-2 was reached in 7 (58.3%) of 12 patients compared with 1/10 (10.0%) patients in the CG1 and 3/12 (12.0%) in the CG2. CONCLUSIONS: This study demonstrated the potential for existing microsurgical techniques to provide good outcomes in 58% of microsurgically treated patients as a third-tier option.

• Klíčová slova
• Stroke, Thrombectomy, Thrombolysis,
• MeSH
• arteria carotis interna chirurgie   MeSH
• cévní mozková příhoda * diagnostické zobrazování   chirurgie   MeSH
• endovaskulární výkony * metody   MeSH
• infarkt arteria cerebri media MeSH
• ischemická cévní mozková příhoda * MeSH
• ischemie mozku * diagnostické zobrazování   chirurgie   MeSH
• kohortové studie MeSH
• lidé MeSH
• prospektivní studie MeSH
• retrospektivní studie MeSH
• trombektomie škodlivé účinky   metody   MeSH
• výsledek terapie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• randomizované kontrolované studie MeSH

The athlete's inrun position affects the outcome for take-off in ski jumping. The purpose of this study was to examine the kinematic parameters between skiers' adjacent body segments during their first straight path of the inrun. Elite ski jumpers participated in the study at the World Cup events in Innsbruck, Austria, during the years 1992 through 2001. A video image was taken at a right angle to the tracks of the K-110 (meter) jumping hill. Kinematic data were collected from the lower extremities and trunk of the athletes. Findings indicated that jumpers had diminished ankle and knee joint angles and increased trunk and hip angles over the 10 years. In recent years, the best athletes achieved a further length of their jumps, while they experienced slower inrun average velocity. These results are perhaps explained by several possible contributing factors, such as new technique of the jumper's body kinematics, advancements in equipment technology, and somatotype of the jumpers.

• MeSH
• biologické modely * MeSH
• dospělí MeSH
• klouby fyziologie   MeSH
• lidé MeSH
• longitudinální studie MeSH
• lyžování fyziologie   MeSH
• mechanický stres MeSH
• mladý dospělý MeSH
• plnění a analýza úkolů * MeSH
• počítačová simulace MeSH
• pohyb fyziologie   MeSH
• tření MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Multiwall WS2 nanotubes have been synthesized from W18O49 nanowhiskers in substantial amounts for more than a decade. The established growth model is based on the "surface-inward" mechanism, whereby the high-temperature reaction with H2S starts on the nanowhisker surface, and the oxide-to-sulfide conversion progresses inward until hollow-core multiwall WS2 nanotubes are obtained. In the present work, an upgraded in situ SEM μReactor with H2 and H2S sources has been conceived to study the growth mechanism in detail. A hitherto undescribed growth mechanism, named "receding oxide core", which complements the "surface-inward" model, is observed and kinetically evaluated. Initially, the nanowhisker is passivated by several WS2 layers via the surface-inward reaction. At this point, the diffusion of H2S through the already existing outer layers becomes exceedingly sluggish, and the surface-inward reaction is slowed down appreciably. Subsequently, the tungsten suboxide core is anisotropically volatilized within the core close to its tips. The oxide vapors within the core lead to its partial out-diffusion, partially forming a cavity that expands with reaction time. Additionally, the oxide vapors react with the internalized H2S gas, forming fresh WS2 layers in the cavity of the nascent nanotube. The rate of the receding oxide core mode increases with temperatures above 900 °C. The growth of nanotubes in the atmospheric pressure flow reactor is carried out as well, showing that the proposed growth model (receding oxide core) is also relevant under regular reaction parameters. The current study comprehensively explains the WS2 nanotube growth mechanism, combining the known model with contemporary insight.

• Klíčová slova
• WS2 nanotube, electron microscopy, ex situ, in situ, reaction mechanism, sulfidation,
• Publikační typ
• časopisecké články MeSH

A mechanistic study into the carcinogenic action of N-nitrosoureas (NU) was carried out with the aid of the semiempirical MINDO/3 method. The proposed reaction pathways of NU biodegradation mechanisms were examined and the most probable one was identified on the ground of theoretical considerations. The calculations of reaction enthalpies confirmed NU as SN1 reagents. The reactivity of a series of NU molecules (both isolated and under the solvent influence) were studied with respect to the detection of possible determinants of the relative carcinogenic potency. The correlations revealed a key function of the nitrosogroup and of the N3-C7 fragment in the decomposition process. The role of the transport properties and lipophilicity of parent NU molecules in the initial steps of the mechanism of carcinogenic effects was demonstrated as well.

• MeSH
• alkylace MeSH
• biotransformace MeSH
• chemické modely MeSH
• experimentální nádory chemicky indukované   MeSH
• krysa rodu Rattus MeSH
• nitrosomočovinové sloučeniny toxicita   MeSH
• termodynamika MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• nitrosomočovinové sloučeniny MeSH

A series of experiments on 78 albino mice demonstrated that cultivation in the presence of tuberculin of spleen cells of animals sensitized by BCG vaccine results in an increase of the number of cells producing antibodies to autologous, isologous and heterologous erythrocytes. This also applies to the cultivation of bone marrow cells. Thymus cells neutralize the stimulation of bone marrow cells. The conclusion has been drawn that autoantibodies are synthesized by B-lymphocytes stimulated during the specific immune reaction to microbial antigens. This process is controlled by the thymus whose cells have a suppressive effect on the synthesis of autoantibodies.

• MeSH
• aktivace lymfocytů MeSH
• autoprotilátky biosyntéza   MeSH
• B-lymfocyty imunologie   MeSH
• BCG vakcína MeSH
• erytrocyty imunologie   MeSH
• myši MeSH
• ovce krev   MeSH
• T-lymfocyty imunologie   MeSH
• tuberkulin imunologie   MeSH
• vakcinace MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• autoprotilátky MeSH
• BCG vakcína MeSH
• tuberkulin MeSH

17α-Estradiol (αE2) is a natural diastereoisomer of 17β-estradiol (E2). It is well known that αE2 can bind to estrogen receptors. However, its biological activity is less than that of E2 and is species and tissue specific. The goal of our study was to propose the mechanism of αE2 hormonal response in rat sperm during their capacitation in vitro and compare it with a previously studied mouse model. Concentration changes in externally added αE2 during capacitation of rat sperm were monitored by the high-performance liquid chromatographic method with tandem mass spectrometric detection (HPLC-MS/MS). The calculated values of relative concentrations Bt were subjected to kinetic analysis. The findings indicated that αE2 in rat sperm did not trigger autocatalytic reaction, in contrast to the mouse sperm, and that the initiation of the hormone penetration through the sperm plasma membrane was substantially faster in rats.

• Klíčová slova
• 17α-estradiol, HPLC MS/MS, capacitation, estrogen receptors, kinetics, rat, sperm,
• MeSH
• estradiol * chemie   MeSH
• kapacitace spermií * fyziologie   MeSH
• kinetika MeSH
• krysa rodu Rattus MeSH
• myši MeSH
• sperma metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• estradiol * MeSH

Lactic acid bacteria (LABs) have emerged as a significant area of study within the field of probiotics due to their diverse health benefits and wide application. This review examines the various methods used to evaluate the antioxidant activity of LABs, including in vitro chemical evaluation methods, cell model evaluation methods, and in vivo evaluation methods. Comprehensive overview of the various assessment techniques employed to elucidate the multifaceted roles of LABs in enhancing the body's natural defenses against oxidative damage. Moreover, this review emphasizes several pivotal aspects of the antioxidant effects of LABs, including the activation of the antioxidant signal pathway, the induction of antioxidative enzymes, the formation of a ROS-binding system, the production of metabolites, the enhancement of intestinal barrier integrity, the activation of the oxidative damage repair system, and the assurance of mitochondrial function. These represent the key antioxidant effects of LABs. The synthesis of this information advances our understanding of the dynamic and diverse antioxidant effects of LABs, providing a foundation for further research into their therapeutic applications in combating oxidative stress-related disorders. Future research should employ multi-omics technologies, genetic engineering, studies on synergistic effects, and large-scale clinical trials to further elucidate the molecular mechanisms underlying the antioxidant effects of LABs. This will promote their application in functional foods, pharmaceuticals, and cosmetics, providing a scientific basis for the development of more efficient antioxidant products.

• Klíčová slova
• Antioxidant activity, Evaluation system, Lactic acid bacteria, Regulation mechanism,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

OBJECTIVE: To elucidate the mechanism of hypotension following intravenous administration of paracetamol (acetaminophen) to patients on the Intensive Care Unit. DESIGN: Prospective observational cross-over study. SETTING: Intensive Care Unit, University Hospital Královské Vinohrady, Prague, Czech Republic. METHODS: Ventilated critically ill patients monitored by PiCCO and administered intravenous paracetamol at the same time were eligible for the study. We recorded haemodynamic indices, as well as core and peripheral temperatures, continuously for 3 h after the dose of paracetamol. Ranitidine was then used as a control drug known not to influence haemodynamics. RESULTS: We included 6 subjects, and recorded 48 cycles of observations after administration of paracetamol, and 35 cycles after administration of the control drug. Haemodynamic parameters were not different at the baseline and administration of control drug did not result in any change in haemodynamics. After intravenous paracetamol, mean arterial pressure (MAP) dropped by 7% (p<0.001) with a nadir at the 19th minute. In 22 measurement cycles (45%) we noted >15% reduction in MAP with paracetamol. Analysis of these cycles suggests that hypotension with paracetamol can be caused by reduction of both cardiac index and systemic vascular resistance. In febrile cycles paracetamol caused narrowing of the gradient between central and peripheral temperatures suggesting skin vasodilation. These changes were not correlated to a change of systemic vascular resistance at any time point. CONCLUSION: Hypotension with intravenous paracetamol in critically ill patients is caused by a reduction of both cardiac output and systemic vascular resistance. We did not demonstrate any relation between haemodynamic changes and antipyretic action of paracetamol. A possibility that cardiac output is reduced with paracetamol might be clinically important.

• Klíčová slova
• Acetaminophen, Cardiac output, Haemodynamics, Hypotension, Paracetamol,
• MeSH
• antipyretika škodlivé účinky   MeSH
• hemodynamika účinky léků   MeSH
• hypotenze chemicky indukované   patofyziologie   MeSH
• intravenózní infuze MeSH
• klinické křížové studie MeSH
• kritický stav MeSH
• lidé středního věku MeSH
• lidé MeSH
• paracetamol aplikace a dávkování   škodlivé účinky   MeSH
• prospektivní studie MeSH
• senioři MeSH
• tělesná teplota účinky léků   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• pozorovací studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antipyretika MeSH
• paracetamol MeSH