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Human memory is prone to errors in many everyday activities but also when cultivating hobbies such as traveling and/or learning a new language. For instance, while visiting foreign countries, people erroneously recall foreign language words that are meaningless to them. Our research simulated such errors in a modified Deese-Roediger-McDermott paradigm for short-term memory with phonologically related stimuli aimed at uncovering behavioral and neuronal indices of false memory formation with regard to time-of-day, a variable known to influence memory. Fifty-eight participants were tested in a magnetic resonance (MR) scanner twice. The results of an Independent Component Analysis revealed encoding-related activity of the medial visual network preceding correct recognition of positive probes and correct rejection of lure probes. The engagement of this network preceding false alarms was not observed. We also explored if diurnal rhythmicity influences working memory processes. Diurnal differences were seen in the default mode network and the medial visual network with lower deactivation in the evening hours. The GLM results showed greater activation of the right lingual gyrus, part of the visual cortex and the left cerebellum in the evening. The study offers new insight into the mechanisms associated with false memories, suggesting that deficient engagement of the medial visual network during the memorization phase of a task results in short-term memory distortions. The results shed new light on the dynamics of working memory processes by taking into account the effect of time-of-day on memory performance., (© 2023. The Author(s).)

We applied detrended fluctuation analysis, power spectral density, and eigenanalysis of detrended cross-correlations to investigate fMRI data representing a diurnal variation of working memory in four visual tasks: two verbal and two nonverbal. We show that the degree of fractal scaling is regionally dependent on the engagement in cognitive tasks. A particularly apparent difference was found between memorisation in verbal and nonverbal tasks. Furthermore, the detrended cross-correlations between brain areas were predominantly indicative of differences between resting state and other tasks, between memorisation and retrieval, and between verbal and nonverbal tasks. The fractal and spectral analyses presented in our study are consistent with previous research related to visuospatial and verbal information processing, working memory (encoding and retrieval), and executive functions, but they were found to be more sensitive than Pearson correlations and showed the potential to obtain other subtler results. We conclude that regionally dependent cognitive task engagement can be distinguished based on the fractal characteristics of BOLD signals and their detrended cross-correlation structure., (© 2022. The Author(s).)

This study applies a neutrosophic-entropy-based clustering algorithm (NEBCA) to analyze the fMRI signals. We consider the data obtained from four different working memory tasks and the brain's resting state for the experimental purpose. Three non-overlapping clusters of data related to temporal brain activity are determined and statistically analyzed. Moreover, we used the Uniform Manifold Approximation and Projection (UMAP) method to reduce system dimensionality and present the effectiveness of NEBCA. The results show that using NEBCA, we are able to distinguish between different working memory tasks and resting-state and identify subtle differences in the related activity of brain regions. By analyzing the statistical properties of the entropy inside the clusters, the various regions of interest (ROIs), according to Automated Anatomical Labeling (AAL) atlas crucial for clustering procedure, are determined. The inferior occipital gyrus is established as an important brain region in distinguishing the resting state from the tasks. Moreover, the inferior occipital gyrus and superior parietal lobule are identified as necessary to correct the data discrimination related to the different memory tasks. We verified the statistical significance of the results through the two-sample t -test and analysis of surrogates performed by randomization of the cluster elements. The presented methodology is also appropriate to determine the influence of time of day on brain activity patterns. The differences between working memory tasks and resting-state in the morning are related to a lower index of small-worldness and sleep inertia in the first hours after waking. We also compared the performance of NEBCA to two existing algorithms, KMCA and FKMCA. We showed the advantage of the NEBCA over these algorithms that could not effectively accumulate fMRI signals with higher variability.

Using a visual short-term memory task and employing a new methodological approach, we analyzed neural responses from the perspective of the conflict level and correctness/erroneous over a longer time window. Sixty-five participants performed the short-term memory task in the fMRI scanner. We explore neural spatio-temporal patterns of information processing in the context of correct or erroneous response and high or low level of cognitive conflict using classical fMRI analysis, surface-based cortical data, temporal analysis of interpolated mean activations, and machine learning classifiers. Our results provide evidence that information processing dynamics during the retrieval process vary depending on the correct or false recognition-for stimuli inducing a high level of cognitive conflict and erroneous response, information processing is prolonged. The observed phenomenon may be interpreted as the manifestation of the brain's preparation for future goal-directed action., (© 2022. The Author(s).)

The dataset contains structural T1-weighted magnetic resonance brain imaging data from 136 young individuals (87 females; age range from 18 to 35 years old) along with questionnaire-assessed measurements of trait-like chronotype, sleep quality and daytime sleepiness. The recruitment criteria excluded individuals with self-reported history of psychiatric or neurological conditions and current medication use. All the brain imaging sessions were performed between 5:20 PM and 8:55 PM in order to control the effect of time of day on acquired images. The data is mostly useful to scientists interested in circadian rhythmicity. It can be deployed in large-scale multicenter meta-analyzes investigating the structural brain correlates of chronotypes in humans. Additionally, the data could be of use in investigations into the effects of sleeping habits and latitude on brain anatomy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s). Published by Elsevier Inc.)

Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 ± 3.56 y.o.) performed in MR scanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects' responses were modeled with a general linear model, which includes as a predictor the non-linear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ceglarek, Ochab, Cifre, Fafrowicz, Sikora-Wachowicz, Lewandowska, Bohaterewicz, Marek and Chialvo.)

The time-of-day along with the synchrony effect (better performance at optimal times of the day according to the chronotype) on the cognitive performance has been well established in previous research. This influence is mediated by both circadian and homeostatic processes consistent with the Borbély two-process model. This experiment focused on the objective and subjective performance of the visual short-term memory task requiring holistic processing. Sixty-five young, healthy participants including 40 females were divided into morning and evening types and performed a given task in two sessions - in the morning and in the evening. Type division was made according to the chronotype questionnaire and polymorphism of the PER3 clock gene. The task was a modified version of Deese-Roediger-McDermott paradigm adjusted to study short-term memory, in which visual, abstract stimuli were used. The analysis was based on an exploratory approach investigating the influence of circadian and individual (sex) factors on execution of memory task. Evening types were more accurate in the task compared to morning types, regardless of the part of the day. The time-of-day effect was revealed on objective measures (reaction times for hits and false alarms) and subjective effort put into the performance. The reaction times were slower in the morning unlike the effort that was greater in the evening. The time-of-day × sex interaction was observed in the case of subjective effort: men described the task as more demanding in the evening. The results could be explained by differences in hemispheric dominance depending on the time-of-day. The report provides new patterns of behavioral data analysis, investigating sex aspects and use of self-assessment scales of performance.

Significant differences exist in human brain functions affected by time of day and by people's diurnal preferences (chronotypes) that are rarely considered in brain studies. In the current study, using network neuroscience and resting-state functional MRI (rs-fMRI) data, we examined the effect of both time of day and the individual's chronotype on whole-brain network organization. In this regard, 62 participants (39 women; mean age: 23.97 ± 3.26 years; half morning- versus half evening-type) were scanned about 1 and 10 h after wake-up time for morning and evening sessions, respectively. We found evidence for a time-of-day effect on connectivity profiles but not for the effect of chronotype. Compared with the morning session, we found relatively higher small-worldness (an index that represents more efficient network organization) in the evening session, which suggests the dominance of sleep inertia over the circadian and homeostatic processes in the first hours after waking. Furthermore, local graph measures were changed, predominantly across the left hemisphere, in areas such as the precentral gyrus, putamen, inferior frontal gyrus (orbital part), inferior temporal gyrus, as well as the bilateral cerebellum. These findings show the variability of the functional neural network architecture during the day and improve our understanding of the role of time of day in resting-state functional networks., Competing Interests: The authors declare no conflict of interest.

Compared to young adults, older adults are more susceptible to endorse false memories as genuine and exhibit higher confidence in their decisions to do so. While most studies to date have addressed this phenomenon in the context of episodic memory, the literature on age-differences in false recognition during short-term memory (STM) is scarce. Hence, the present study investigated age-related differences in the rate of false alarms (FA) and subsequent confidence judgments in STM. Thirty-three young and thirty-three older adults performed a visual short-term recognition memory task. In each trial, participants encoded a single abstract object, then made a "same" or "different" decision on a subsequent test, followed by a confidence judgment. We found significant age-related differences in performance as measured by the sensitivity index ( d '), but not in the rate of FAs. Older adults were more confident in their erroneous recognition decisions than younger adults. The results are discussed in the context of age-differences in monitoring and associative processes., (Copyright © 2019 Sikora-Wachowicz, Lewandowska, Keresztes, Werkle-Bergner, Marek and Fafrowicz.)

Human performance, alertness, and most biological functions express rhythmic fluctuations across a 24-h-period. This phenomenon is believed to originate from differences in both circadian and homeostatic sleep-wake regulatory processes. Interactions between these processes result in time-of-day modulations of behavioral performance as well as brain activity patterns. Although the basic mechanism of the 24-h clock is conserved across evolution, there are interindividual differences in the timing of sleep-wake cycles, subjective alertness and functioning throughout the day. The study of circadian typology differences has increased during the last few years, especially research on extreme chronotypes, which provide a unique way to investigate the effects of sleep-wake regulation on cerebral mechanisms. Using functional magnetic resonance imaging (fMRI), we assessed the influence of chronotype and time-of-day on resting-state functional connectivity. Twenty-nine extreme morning- and 34 evening-type participants underwent two fMRI sessions: about 1 h after wake-up time (morning) and about 10 h after wake-up time (evening), scheduled according to their declared habitual sleep-wake pattern on a regular working day. Analysis of obtained neuroimaging data disclosed only an effect of time of day on resting-state functional connectivity; there were different patterns of functional connectivity between morning (MS) and evening (ES) sessions. The results of our study showed no differences between extreme morning-type and evening-type individuals. We demonstrate that circadian and homeostatic influences on the resting-state functional connectivity have a universal character, unaffected by circadian typology.

A number of studies have shown that the pupil dilates during stimuli recognition and decision-making. Yet, little is known about the interaction between recognition memory and decision processes. Here, we investigated the possible link between pupil response and decision-related factors during a visual recognition task. Forty-eight volunteers took part in the study. The experimental task was based on the Deese-Roediger-McDermott paradigm designed to study false recognitions. Participants were shown different sets of two meaningless objects. After seeing each set, they were asked to determine whether the subsequent probe (positive, lure or negative) was already presented. We had found that the pupil dilated more and slower, and the reaction time was extended, when the upcoming choice was against individual response bias. Such a result indicates that recognition and rejection in memory tasks could be seen as two behavioral alternatives supported by evidence accumulation, in line with decision-making models. This interpretation was upheld with the drift-diffusion modelling based on pupil data. A similar pattern was observed for errors - larger pupil sizes before incorrect responses were accompanied by longer reaction times. Furthermore, before correct reactions, especially in participants differentiating more accurately between the old and new stimuli, pupil dilation was increasing faster, indicating swifter evidence accumulation. Taking into account the link between cognitive pupillary reflex and norepinephrine release, we conclude that similarly to decision making, reactions in memory tasks may partly depend on the locus coeruleus activity, which is the principal site for norepinephrine synthesis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Across a wide range of tasks, cognitive functioning is affected by circadian fluctuations. In this study, we investigated diurnal variations of working memory performance, taking into account not only hits and errors rates, but also sensitivity (d') and response bias (c) indexes (established by signal detection theory). Fifty-two healthy volunteers performed four experimental tasks twice - in the morning and in the evening (approximately 1 and 10 h after awakening). All tasks were based on Deese-Roediger-McDermott paradigm version dedicated to study working/short-term memory distortions. Participants were to memorize sets of stimuli characterized by either conceptual or perceptual similarity, and to answer if they recognized subsequent stimulus (probe) as an "old" one (i.e. presented in the preceding memory set). The probe was of three types: positive, negative or related lure. In two verbal tasks, memory sets were characterized by semantic or phonological similarity. In two visual tasks, abstract objects were characterized by a number of overlapping similarities or differed in only one detail. The type of experimental material and the participants' diurnal preference were taken into account. The analysis showed significant effect of time of day on false alarms rate (F (1,50)  = 5.29, p = 0.03, η p 2  = 0.1) and response bias (F (1,50)  = 11.16, p = 0.002, η p 2  = 0.18). In other words, in the evening participants responded in more liberal way than in the morning (answering "yes" more often). As the link between variations in false alarms rate, response bias and locus coeruleus activity was indicated in literature before, we believe that our data may be interpreted as supporting the hypothesis that diurnal fluctuations in norepinephrine release have effect on cognitive functioning in terms of decision threshold.

Objectives Platelets, the smallest anucleated blood cells, play an essential role in the first step of complex haemostatic process. This review presents the haemostatic function of blood platelets related to their activation in psychiatric disorders (schizophrenia, depression), the role of antipsychotic and antidepressant medication, and introduces the mechanisms by which activated platelets may be involved in the pathophysiology of these disorders. Methods Platelets are interesting and easily accessible blood cells to study biochemical pathways related to schizophrenia and other psychiatric disorders, and their complex activation process might be useful as a diagnostic peripheral marker for studying psychiatric disorders and haemostatic complications. Results The excessive activation of platelets observed in patients with depression and schizophrenia is involved in cardiovascular diseases, stroke and increased risk of thrombotic complications that may be major causes of morbidity and mortality of patients. The use of antidepressants or antipsychotic drugs in depression and schizophrenia treatment is often associated with haematological side effects such as bleeding, venous thromboembolism and impaired platelet function. Conclusions Understanding the role of platelet activation in psychiatric disorders such as schizophrenia or depression and medication may improve therapies in the future.

Context: The main source of bufadienolides is toad venom; however, plants such as members of Kalanchoe Adans. (Crassulaceae) genus may also synthesize these bioactive substances., Objective: This is the first study on antioxidant effects and cytotoxicity of bufadienolide-rich fraction isolated from Kalanchoe daigremontiana Raym.-Hamet & H. Perrier., Materials and Methods: The methanolic fraction was extracted from the plant roots and contained 0.48 mg bufadienolides/mg of dry mass (11α,19-dihydroksytelocinobufagin, bersaldegenin-1-acetate, bersaldegenin-1,3,5-orthoacetate, 19-(acetyloxy)-3β,5β,11α,14-tetrahydroxyl-12-oxo-bufa-20,22-dienolide and 19-(acetyloxy)-1β,3β,5β,14-tetrahydroxyl-bufa-20,22-dienolide, mainly). The cytotoxicity of K. daigremontiana fraction was evaluated in an in vitro experimental model of blood platelets. The viability of blood platelets was determined on the basis of a release of lactate dehydrogenase., Results: The fraction scavenged DPPH • radicals, with EC 50 of 21.80 μg/mL. Studies on an experimental model of blood plasma under peroxynitrite-induced oxidative stress revealed that the plant preparation had moderate antioxidant properties. Levels of 3-nitrotyrosine and thiol groups indicated that the protective effect of K. daigremontiana was significant mainly for its concentration of 50 μg/mL. No effect was found in prevention of oxidation of low-molecular plasma thiols (glutathione, cysteine and cysteinylglycine). Simultaneously, measurements of lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) indicated that the examined fraction might be effective antioxidant at broader concentration range, that is 1-5 and 25-50 μg/mL for hydroperoxides and TBARS generation, respectively. No cytotoxicity was observed at the concentration range of 1-50 μg/mL., Conclusions: Based on the obtained results, we suggest that antioxidant activity may additionally contribute to beneficial properties of K. daigremontiana-derived extracts.

Increasing evidence indicates that blood platelets contribute to diverse processes that extend beyond hemostasis. Many of the same mechanisms that play a role in hemostasis and thrombosis facilitate platelets the participation in other physiological and pathological processes, particularly in the inflammation, the immune response and central nervous system disorders. Platelets are involved in pathophysiology of central nervous system diseases, especially in the pathogenesis of multiple sclerosis, but their role appears to be neglected. Platelets contribute to the inflammation and cooperate with immune cells in inflammatory and immune responses. These blood cells were identified in inflamed spinal cord and in the brain in chronic active lesions of multiple sclerosis and in the related animal models referred as Experimental Autoimmune Encephalomyelitis. This review summarizes recent insights in the platelet activation accompanied by the exocytosis of bioactive compounds stored in granules, formation of platelet microparticles, expression of specific membrane receptors, synthesis of numerous biomediators, generation of free radicals, and introduces the mechanisms by which activated platelets may be involved in the pathophysiology of multiple sclerosis. Understanding the role of platelets in multiple sclerosis may be essential for improved therapies.

The present in vitro study includes a comparative evaluation of anti-platelet (anti-thrombotic) properties of plant phenolics, isolated from nine different clover (Trifolium) species. The analysis covered phenolic fractions isolated from T. alexandrinum L., T. fragiferum L., T. hybridum L., T. incarnatum L., T. pallidum Waldst et Kit., T. resupinatum L. var. majus Boiss, T. resupinatum L. var. resupinatum, T. scabrum L., and T. pratense L. (red clover). The inhibitory effects of plant preparations (1-50 µg/ml) on hemostatic functions of blood platelets were assessed by measurements of thrombin- or ADP-induced platelet adhesion to fibrinogen, platelet aggregation in platelet-rich plasma (activated with ADP or collagen), and by the determination of PF-4 secretion from platelet α-granules. The influence of T. phenolics on arachidonic cascade in blood platelets was also determined. T. resupinatum var. majus, T. resupinatum var. resupinatum, and T. scabrum had the strongest anti-platelet effects. These preparations displayed the most evident anti-adhesive and anti-aggregatory effects in response to all of the used agonists: thrombin (0.2 U/ml), ADP (10 µM), and collagen (2 µg/ml), and their inhibitory properties were also confirmed by an analysis of PF-4 secretion. T. scabrum and some of other examined clover species possess significantly higher concentrations of both isoflavones and other bioactive phenolics, when compared to red clover. The obtained results suggest that these clovers contain substances with potent anti-platelet properties.

Circadian rhythms and restricted sleep length affect cognitive functions and, consequently, the performance of day to day activities. To date, no more than a few studies have explored the consequences of these factors on oculomotor behaviour. We have implemented a spatial cuing paradigm in an eye tracking experiment conducted four times of the day after one week of rested wakefulness and after one week of chronic partial sleep restriction. Our aim was to verify whether these conditions affect the number of a variety of saccadic task errors. Interestingly, we found that failures in response selection, i.e. premature responses and direction errors, were prone to time of day variations, whereas failures in response execution, i.e. omissions and commissions, were considerably affected by sleep deprivation. The former can be linked to the cue facilitation mechanism, while the latter to wake state instability and the diminished ability of top-down inhibition. Together, these results may be interpreted in terms of distinctive sensitivity of orienting and alerting systems to fatigue. Saccadic eye movements proved to be a novel and effective measure with which to study the susceptibility of attentional systems to time factors, thus, this approach is recommended for future research.

Platelets are the smallest, depleted of nucleus blood cells which contain a typical cellular organelles including the mitochondria, so that have active metabolism. Platelets possess the highly organized cytoskeleton, specific secretory granules and unique membrane receptors system responsible for their high reactivity. The key role of blood platelets is to maintain normal hemostasis, but they also play important roles in inflammation, immune processes and the cancer progression. The anucleated, small platelets occur in representatives of all clusters of mammals, so it seems to be an adaptation feature. In other vertebrates similar hemostatic functions are played by large nucleated platelets, which are much more weakly reactive. Small, reactive platelets, appearing in the evolution of mammals, allowed the formation of clots faster and slower blood loss in case of injury, but also increased the risk of thromboembolic and cardiovascular diseases. Daily the human body forms about 1x10¹¹ platelets, which are produced by a process of differentiation, maturation and fragmentation of the cytoplasm of mature megakaryocytes. The emergence of platelets is the final stage of megakaryocyte differentiation and is followed by formation of the direct precursors called proplatelets. The anucleated platelets are regarded as terminally differentiated cells, which are not capable of further cell division. However, despite the absence of a nucleus, in blood platelets the synthesis and transcription of mitochondrial DNA and protein synthesis occurring on the basis of mRNA from megakaryocytes has been confirmed. However, recent studies published in 2012 show that the platelets are capable not only of the process of protein synthesis, but also of generation of new cells, which are functionally and structurally similar to the parent platelets.

Clovers (Trifolium) may possess a significant therapeutic potential, but the effects of compounds from these plants on blood platelets and haemostasis have been poorly recognized. The present study was designed to evaluate the antioxidative action of extracts from three species of clovers: Trifolium pratense, Trifolium pallidum and Trifolium scabrum in the protection of human blood platelets in vitro. Platelet suspensions were pre-incubated with crude extract and phenolic fraction of T. pratense or phenolic fractions of T. scabrum and T. pallidum, at the final concentrations of 0.5-50 μg/ml. Then, for the induction of oxidative stress, 100 μM peroxynitrite was added. The antioxidative activity of plant extracts was assessed by measurements of the level of 3-nitrotyrosine, thiol groups and lipid peroxidation products (hydroperoxides and thiobarbituric acid-reactive substances). Despite the significant differences in the composition of the investigated extracts, we observed antioxidative effects of all used mixtures. The presence of Trifolium extracts considerably reduced the peroxynitrite-mediated modifications of proteins and diminished peroxidation of lipids in platelets. Our results indicate on a strong antioxidative activity of the tested extracts-statistically significant effects were found even for the lowest concentrations (0.5 μg/ml) of all extracts. This action may be useful in the protection of blood components, very susceptible to oxidative modifications. The obtained results suggest that the examined clovers are a promising source of compounds, valuable for the protection against oxidative stress-induced damage to blood platelets.

Background: Uric acid (UA) has been suggested to be a marker of multiple sclerosis (MS) activity. Whole body cryostimulation (WBCT) is a new form of additional treatment and becoming popular in medicine., Objectives: The aims of this study were to determine the long-term effects of WBCT on the level of plasma UA in selected group of MS patients only with secondary progressive (SPMS) clinical form and verify results with functional state of patients assessed by expanded disability status scale (EDSS)., Materials and Methods: SPMS patients (n = 22) and healthy controls (n = 22) participated in 10 3-min-long exposures of WBCT (one exposure per day). Results were collected before the WBCT treatment and after completion the WBCT series as well as one and three months later., Results: WBCT increased UA concentration in plasma of SPMS patients not only directly after 10 exposures (p < 0.0001) but also one (p < 0.0001) and three (p < 0.005) months later. Furthermore, WBCT causes positive changes in EDSS scale both directly after WBCT (7% lower) and maintain this level 1 month later as well as 3 month later (5% lower)., Conclusions: WBCT may be used as adjuvant therapy via increase UA blood level; it improves functional status of SPMS patients.

This study was designed to determine and compare the antioxidant effects of synthetic organoselenium compounds. In experimental trials three different diselenides were used: bis(2-hydroxyphenyl) diselenide, bis{[2-(4-hydroxybenzyl)imino]phenyl} diselenide and bis[2-(4-methylphenylsulfonylamino)phenyl] diselenide. The compounds were screened for antioxidant activities in human blood under oxidation stress conditions. Oxidative stress was induced in vitro in human blood platelet samples and in plasma by 0.1 mM peroxynitrite (ONOO(-)) or by Fe(2+). In experimental trials the levels of chosen oxidative stress markers (TBARS, O2(-), and protein carbonyl groups) were significantly decreased by the action of the tested compounds. The antioxidative properties and the changes in proteins and lipids in the presence of new synthesized selenoorganic compounds were studied in vitro and compared with activity of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one)--a classical antioxidant, well known as the most important glutathione peroxidase mimetic agent. Our results indicate that the tested diselenides have distinctly protective effects against oxidative alterations of biomolecules caused by ONOO(-) and Fe(2+) in blood platelets and in plasma. Therefore it seems that not only ebselen with a wide spectrum of therapeutic actions but also other organoselenium compounds can be considered in the future as active pharmacological agents., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Cardiovascular diseases (CVD) remain the principal cause of death in both advanced and developing countries of the world. Blood platelets are involved in the pathogenesis of atherosclerosis and thrombosis. Platelet adhesion and aggregation are critical events that occur in unstable coronary syndromes. The current research is focused on the role of polysaccharide-polyphenolic conjugates isolated from chamomile (Matricaria chamomilla L.) at concentrations of 10, 25, 50 and 100 μg/mL on blood platelets (obtained from healthy donors and from patients received combined anti-platelet therapy complex with clopidogrel and acetylsalicylic acid) aggregation and experimentally induced cell toxicity. The treatment of PRP obtained from healthy donors with polyphenolic-polysaccharide conjugates from M. chamomilla (L.) (MC) resulted in a dose-dependent, decrease of platelet aggregation induced by multiple agonists (ADP, collagen and arachidonic acid). In this study we also observed that the MC reduced platelet aggregation in PRP obtained from patients with cardiovascular disorders. The result of testing the MC on human blood platelets, mouse fibroblast cultures L929 and human lung cells A549 did not show any cytotoxicity effects. Compounds obtained from M. chamomilla L. are potential composite to the development of a new anti-platelet agent, which could be an alternative to the currently used anti-platelet drugs., (Copyright © 2013 Elsevier B.V. All rights reserved.)

LPS (lipopolysaccharide) induces platelet activation and is a well-known fundamental agent of septic shock and disseminated intravascular coagulation (DIC). Biological activity of (1→3)-β-D-glucan is related due to its anti-inflammatory, antioxidant, and antitumor properties. We focus our attention on the (1→3)-β-D-glucan (antiplatelet) properties. The main purpose of our study was to evaluate the influence of (1→3)-β-D-glucan from Saccharomyces cerevisiae on destructive activity of LPS (from Escherichia coli and Pseudomonas aeruginosa) on human blood platelets. We assess biochemically in vitro if (1→3)-β-D-glucan might combat the oxidative stress caused by LPS stroke associated with nitrative and oxidative damages of human platelet biomolecules. We also make an attempt by in silico molecular docking to determine the interactions between the molecules of (1→3)-β-D-glucan and LPS. Our conclusion is that protective mechanism of (1→3)-β-D-glucan against LPS action on blood platelets is due to as well: its antioxidant properties, as to its interaction with LPS-binding region of TLR4-MD-2 complex., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Platelets are the smallest, unnucleated blood cells that play a key role in maintaining normal hemostasis. In the human body about 1x1011 platelets are formed every day, as a the result of complex processes of differentiation, maturation and fragmentation of megakaryocytes. Studies done over 4 decades ago demonstrated that circulating in blood mature platelets can synthesize proteins. Recent discoveries confirm protein synthesis by unnucleated platelets in response to activation. Moreover, protein synthesis alters the phenotype and function of platelets. Platelets synthesize several proteins involved in hemostasis (COX, αIIbβ3, TF PAI-1, Factor XI, protein C inhibitor) and in inflammatory process (IL-1β, CCL5/RANTES). In spite of lack of transcription platelets have a stable mRNA transcripts with a long life correlated with platelet life span. Platelets also show expression of two important key regulators of translation eIF4E and EIF-2α and have a variety of miRNA molecules responsible for translational regulation. This article describes the historical overview of research on protein synthesis by platelets and presents the molecular mechanisms of protein synthesis in activated platelets (and synthesis of the most important platelet proteins).

Clovers (genus: Trifolium) have been used in traditional medicine by many cultures, but the biological activity of the most of these plants still remains unknown. The aim of our in vitro study was to assess the antioxidative action of phenolic extracts from aerial parts of Trifolium scabrum and Trifolium pallidum in human blood plasma, exposed to oxidative stress. In the present study we also demonstrate, for the first time the effects of the tested extracts on coagulative properties and fibrinolytic activity of blood plasma. The protective properties of the examined extracts (0.5-50 μg/ml) against peroxynitrite-induced oxidative stress were estimated by the measurements of 3-nitrotyrosine, thiol groups and the thiobarbituric acid-reactive substances levels. The extracts considerably prevented the oxidative and nitrative damage to plasma proteins. Even the lowest doses of the Trifolium extracts (0.5 μg/ml) were able to markedly reduce 3-nitrotyrosine formation (by about 50%) and to increase the level of -SH groups (by about 30%), in comparison to the plasma exposed to ONOO(-) in the absence of the extracts. The protective action of all the used concentrations of the Trifolium extracts in the prevention of lipid peroxidation was also found. The tested extracts influenced neither the coagulative properties nor fibrinolytic activity of plasma. Moreover, the extracts were able to significantly reduce the inhibitory effect of ONOO(-) on fibrinolytic activity of plasma (assessed with the use of a chromogenic substrate for plasmin).

The diseases of blood circulation system--cardiovascular diseases are the main causes of mortality in developing, low and middle-income countries all over the world. The specialists recommend the prophylaxis to avoid the dangerous complications connected with these diseases, what can reduce the final treatment costs. All over the world there is continuous research of novel, therapeutically better, more effective anticoagulant or anti-platelet agents, with multiple targets, without so many side effects. Plant material is a good source to do this kind of research. The authors show the results of their few years research on polyphenolic-polysaccharide plant conjugates, isolated from medicinal plants, popular in Poland, which is continuing in the framework of the project WROVASC--Integrated Center of Cardiovascular Medicine. This research group has been working on isolation, structure characterization and biological activity of these macromolecular compounds. Because of anticoagulant, antioxidant as well as anti-platelet properties of these plant structures they are promising to be a new source of the innovative therapeutic agent.

A growing number of reports indicate that some species of clover (Trifolium) may have remarkable medical importance; however, the effects of these plants on blood platelets and hemostasis are inadequately recognized. This work was designed to study the effects of Trifolium pallidum and Trifolium scabrum extracts on the functions of human blood platelets in vitro. Platelet suspensions were preincubated with extracts from aerial parts of T. pallidum (phenolic fraction and clovamide fraction) and T. scabrum (phenolic fraction) at the final concentrations of 12.5, 25, and 50 µg/ml. Then, for platelet activation thrombin (0.1 U/ml), thrombin receptor activating peptide (TRAP; 20 µM), or adenosine diphosphate (ADP; 1 µM) were used. The effects of Trifolium extracts on adhesion of blood platelets to fibrinogen and collagen were determined by enzyme-linked immunosorbent assay (ELISA) method. Platelet aggregation was monitored on a dual-channel Chronolog aggregometer. In these studies, we also compared the action of tested plant extracts with the effects of another antiplatelet plant-derived compound - resveratrol (3,4',5-trihydroxystilbene). The performed assays demonstrated that the tested extracts might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of all tested extracts on adhesion of thrombin-stimulated platelets to collagen was found. Both extracts from T. pallidum and from T. scabrum reduced the thrombin-induced platelet adhesion to fibrinogen. Furthermore, in the presence of all three extracts, the platelet aggregation induced by thrombin was slightly inhibited. Our results also indicate that the tested plant extracts (at the highest concentrations used of 50 µg/ml), similar to purified resveratrol, inhibit selected steps of platelet activation stimulated by both proteolytic (thrombin) and nonproteolytic agonists (TRAP or ADP). In the comparative studies, T. pallidum and T. scabrum extracts was not found to be more effective antiaggregatory factor, than resveratrol. Extracts from T. pallidum and T. scabrum aerial parts reveal antiplatelet properties: the antiadhesive effect was similar to that of the reference compound resveratrol, whereas the antiaggregant effect was less marked. The results obtained suggest that these plants may be a promising source of natural compounds, valuable in the prevention of the enhanced activity of blood platelets in numerous cardiovascular diseases, observed in menopausal or postmenopausal women.

Fibrinogen appears to be particularly sensitive to toxic action of peroxynitrite; a potent oxidizing and nitrating species. An increased nitration of fibrinogen has been reported in cardiovascular diseases. The defense mechanisms against PN are crucial for complex hemostasis process. Flavonoids have antioxidative properties and could protect biomolecules against action of peroxynitrite. The aim of our studies was to establish, if (-)-epicatechin may in vitro protect fibrinogen molecule against peroxynitrite-induced nitration of tyrosines and change its thrombin-catalyzed polymerization. The exposure of purified fibrinogen (6 μM) to peroxynitrite (1-100 μM) resulted in both structural modifications and clotting ability of this glycoprotein. Peroxynitrite at the concentration of 1 μM increased maximum velocity of Fg polymerization, whereas exposure to 100 μM PN resulted in a significant decrease of Vmax. (-)-Epicatechin (1-100 μM) caused a dose-dependent inhibition of 3-nitrotyrosine formation in fibrinogen treated with peroxynitrite (100 μM) in both Western blot assays and C-ELISA assays. At the highest concentration of (-)-epicatechin (100 μM) the level of 3-NT in fibrinogen reached the control values. At lower doses (-)-epicatechin reduced tyrosine nitration by approx. 23% and 40% at the concentration of 1 μM and 10 μM, respectively. (-)-Epicatechin also abolished the pro-thrombotic effect of peroxynitrite on fibrinogen clotting. The presented in vitro results demonstrated for the first time that (-)-epicatechin might have protective effects against the impairment of structure and properties of Fg, caused by action of the strong biologic oxidant/nitration and inflammatory mediators., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The mechanisms of oxidative stress in schizophrenic patients are not fully understood. In the present study, we investigated the effect of elevated level of homocysteine (Hcys) on some parameters of oxidative stress, namely thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation in plasma, the level of carbonyl groups in plasma proteins, as well as the amount of 3-nitrotyrosine in plasma proteins isolated from schizophrenic patients. Patients hospitalised in I and II Psychiatric Department of Medical University in Lodz, Poland were interviewed with special questionnaire (treatment, course of diseases, dyskinesis and other EPS). According to DSM-IV criteria all patients had diagnosis of paranoid type. They were treated with antipsychotic drugs (clozapine, risperidone, olanzapine). Mean time of schizophrenia duration was about 5 years. High-performance liquid chromatography was used to analyse the total level of homocysteine in plasma. Levels of carbonyl groups and 3-nitrotyrosine residues in plasma proteins were measured by ELISA and a competition ELISA, respectively. The lipid peroxidation in plasma was measured by the level of TBARS. Our results showed that in schizophrenic patients the amount of homocysteine in plasma was higher in comparison with the control group. We also observed a statistically increased level of biomarkers of oxidative/nitrative stress such as carbonyl groups or 3-nitrotyrosine in plasma proteins from schizophrenic patients. Moreover, our experiments indicate that the correlation between the increased amount of homocysteine and the oxidative stress exists. Considering the data presented in this study, we suggest that the elevated Hcys in schizophrenic patients may stimulate the oxidative stress.

Mechanisms of homocysteine (Hcy) contribution to thrombosis are complex and only partly recognized. The available data suggest that the prothrombotic activity of homocysteine may be not only a result of the changes in coagulation process and endothelial dysfunction, but also the dysfunction of fibrinolysis. The aim of the present work was to assess the effects of homocysteine (10-100 μM mM) and its thiolactone (HTL, 0.1-1 μM) on plasminogen and plasmin functions in vitro. The amidolytic activity of generated plasmin in Hcy or HTL-treated plasminogen and plasma samples was measured by the hydrolysis of chromogenic substrate. Effects of Hcy and HTL on proteolytic activity of plasmin were monitored electrophoretically, by using of fibrinogen as a substrate. The exposure of human plasma and purified plasminogen to Hcy or HTL resulted in the decrease of urokinase-induced plasmin activity. In plasminogen samples treated with the highest concentration of homocysteine (100 μM) or thiolactone (1 μM), the activity of plasmin was inhibited by about 50%. In plasma samples, a reduction of amidolytic activity by about 30% (for 100 μM Hcy) and 40% (for 1 μM HTL), was observed. Both Hcy and HTL were also able to diminish the streptokinase-induced proteolytic activity of plasmin. In conclusion, the results obtained in this study demonstrate that Hcy and HTL may affect fibrinolytic properties of plasminogen and plasma, leading to the decrease of plasmin activity., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Since the extract from berries of Aronia melanocarpa presents antioxidative properties in plasma and in blood platelets, not only from healthy group, but also from patients with benign breast diseases and in patients with invasive breast cancer before surgery, the aim of our present study was to evaluate the oxidative stress by measuring the level of various biomarkers of this process such as the generation of superoxide anion radicals (O(2)(-·)), the amount of carbonyl groups and 3-nitrotyrosine in proteins or the amount of glutathione in blood platelets isolated from breast cancer patients after the surgery and after various phases of the chemotherapy in the presence of A. melanocarpa extract (Aronox) in vitro. We demonstrated in platelet proteins from patients with invasive breast cancer (after the surgery and after various phases of the chemotherapy) higher level of carbonyl groups than in control healthy group. The level of 3-nitrotyrosine in platelet proteins from patients with invasive breast cancer was also significantly higher than in healthy subject group. We observed an increase of other biomarkers of oxidative stress such as O(2)(-·) and a decrease of GSH in platelets from patients with breast cancer (after the surgery and after various phases of the chemotherapy) compared to the healthy group. In model system in vitro our results showed that the commercial extract from berries of A. melanocarpa due to antioxidant action, significantly reduced the oxidative/nitrative stress in platelets from patients with invasive breast cancer caused by the surgery and various phases of the chemotherapy., (Published by Elsevier B.V.)

Objectives: In breast cancer patients dysregulation of reactive oxygen species metabolism, as detected by various indicators in plasma or various blood cells, including red blood cells and blood platelets, is observed., Design and Methods: The aim of our study was to explain the effect of oxidative/nitrative stress on hemostatic activity of plasma from breast cancer patients. Different methods were used to analyze oxidative/nitrative stress (carbonyl groups and 3-nitrotyrosine levels - ELISA and C-ELISA method, respectively and free thiol groups was estimated with 5,5'-dithio-bis(2-nitro-benzoic acid)). We also measured total antioxidant status (TAS) in plasma., Results: Our results showed the correlation between the oxidative stress and changes of hemostasis in breast cancer patients; the correlation between the increased amount of carbonylated or nitrated plasma proteins and fibrin polymerization or lysis in plasma isolated from invasive breast cancer patients. We also observed that the relationship between TAS and fibrin polymerization or lysis in plasma from invasive breast cancer exists., Conclusion: Considering the data presented in this study, we suggest that the oxidative/nitrative stress in breast cancer patients may induce the changes of hemostasis in these patients., (Published by Elsevier Inc.)

Mechanisms involved in the reduction of blood platelet functions by various plant extract, including the grape seeds extract (rich in phenolic compounds, a mixture of about 95% oligomeric phenols; GSE) are still unclear. In the literature there are few papers describing studies on the effects of GSE on selected element of hemostasis. The aim of our study was to establish and compare the influence of GSE (at final dose of 0.625-50 µg/ml) and resveratrol (3,4',5 - trihydroxystilben), a phenolic compound synthesized in grapes and vegetables and presents in wine, which has been supposed to be beneficial for the prevention of cardiovascular events, on different steps of platelet activation. We measured the effects of GSE and resveratrol on platelet aggregation, the surface expression of P-selectin, platelet microparticle formation (PMP), and superoxide anion radicals ([Formula: see text]) production in blood platelets stimulated by TRAP and thrombin. P-selectin expression and PMP formation were measured by a flow cytometer. In gel-filtered platelets activated by thrombin or TRAP and treated with different concentrations of GSE (1.25-50 µg/ml) a significant decrease of P-selectin expression, PMP formation and platelet aggregation was observed. GSE caused also a dose-dependent reduction of [Formula: see text] produced in platelets activated by TRAP or thrombin. Our present results indicate that GSE inhibits platelet signaling pathways trigged by both proteolytic (thrombin) and non-proteolytic agonist (TRAP). In the comparative studies, GSE was found to be more effective antiplatelet factor, than the solution of pure resveratrol. Thus, the polyphenol-rich extract from grape seeds can be useful as the protecting factor against cardiovascular diseases.

Numerous plants (including clovers) have been widely used in folk medicine for the treatment of different disorders. This in vitro study was designed to examine the antioxidative effects of the clovamide-rich fraction, obtained from aerial parts of Trifolium pallidum, in the protection of blood platelets and plasma against the nitrative and oxidative damage, caused by peroxynitrite (ONOO(-)). Carbonyl groups and 3-nitrotyrosine in blood platelet and plasma proteins were determined by ELISA tests. Thiol groups level was estimated by using 5,5'-dithio-bis(2-nitro-benzoic acid, DTNB). Plasma lipid peroxidation was measured spectrophotometrically as the production of thiobarbituric acid reactive substances. The results from our work indicate that clovamide-rich T. pallidum extract may reveal the protective properties in the prevention against oxidative stress. The presence of clovamide-rich T. pallidum extract (12.5-100 μg/ml) partly inhibited ONOO(-)-mediated protein carbonylation and nitration. All the used concentrations of T. pallidum extract reduced lipid peroxidation in plasma. The antioxidative action of the tested extract in the protection of blood platelet lipids was less effective; the extract at the lowest final concentration (12.5 μg/ml) had no protective effect against lipid peroxidation. The present results indicate that the extract from T. pallidum is likely to be a source of compounds with the antioxidative properties, useful in the prevention against the oxidative stress-related diseases.

Oxidative stress has been implicated in the pathogenesis of variety of diseases. Since the endogenous antioxidant defense may be not adequate to counteract the enhanced generation of oxidants, a growing interest in research for exogenous nutrients has been observed. The present study was designed to assess in vitro the antioxidative properties of the glucose derivatives: calcium D-glucarate, D-gluconic acid lactone, and sodium D-gluconate (0.5-3 mM) in the protection of plasma proteins and lipids, against the damage caused by 0.1 mM peroxynitrite (ONOO⁻). Exposure of plasma to ONOO⁻ resulted in carbonyl groups increase, 3-nitrotyrosine (3-NT) formation, reduction in thiol groups, and enhanced lipid peroxidation. D-gluconic acid lactone and sodium D-gluconate effectively decreased 3-NT formation; the antinitrative action of calcium D-glucarate was less effective. In plasma samples incubated with ONOO⁻ and tested compounds, the level of carbonyl groups was decreased in comparison to plasma samples treated only with ONOO⁻. The level of protein -SH groups and glutathione was significantly higher in the presence of glucose derivatives than in plasma samples treated with ONOO⁻ only. All the tested compounds had the inhibitory effect on the peroxynitrite-induced plasma lipids peroxidation. The results obtained from our work indicate that calcium D-glucarate, D-gluconic acid lactone, and sodium D-gluconate may partly protect plasma proteins and lipids against peroxynitrite-induced damages.

Objective: L-Carnitine as a dietary supplement has been reported to have a beneficial effect on several cardiovascular risk parameters and exercise capacity, but the biological relevance of its activity is poorly understood. Dietary supplements (including L-carnitine) are often used to foster exercise performance; however, these may affect some pathways of human body metabolism. The aim of this study in vitro was to determine antioxidative properties of L-carnitine (0.1-100 μM) added to plasma and to assess if L-carnitine might protect plasma proteins and lipids against oxidative/nitrative damage (determined by levels of protein carbonyl groups, thiols, 3-nitrotyrosine formation and thiobarbituric-acid reactive substances generation) caused by 100 μM peroxynitrite (ONOO(-)), a strong physiologic oxidative/nitrative agent., Methods: The level of carbonyl group generation was measured by a colorimetric method. For the estimation of 3-nitrotyrosine formation, a competition enzyme-linked immunosorbent assay was performed. Plasma lipid peroxidation was measured spectrophotometrically as the production of thiobarbituric-acid reactive substances. High-performance liquid chromatography was used to analyze total free thiol groups of plasma proteins and low-molecular-weight thiols (glutathione, cysteine, and homocysteine) in plasma., Results: The L-carnitine added to plasma inhibited in vitro ONOO(-)-induced oxidation and nitration of blood plasma proteins. Incubation of plasma with peroxynitrite resulted in the decrease of protein thiols. L-Carnitine had a protective effect on peroxynitrite-induced decreased -SH level in plasma proteins. The presence of L-carnitine also prevented the decrease of low-molecular-weight thiols (glutathione, cysteine, and homocysteine) in plasma caused by peroxynitrite and protected plasma lipids against peroxidation induced by peroxynitrite., Conclusions: These results demonstrated that L-carnitine possesses antioxidative activity., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Aim: The antioxidative and antinitrative activities of (1→3)-β-D-glucan (1-4μg/ml) from the yeast cell walls of Saccharomyces cerevisiae in human plasma treated with strong oxidants - peroxynitrite (ONOO(-)) (0.1mM) and hydrogen peroxide (H(2)O(2)) (2mM) were studied in vitro. The main purpose of this study was to assess if (1→3)-β-D-glucan, a well known strong immunostimulatory agent, possesses a protective function against dual mechanism of ONOO(-) stroke associated with nitrative and oxidative damages to human plasma biomolecules., Scope: The protein changes were determined in vitro by estimating the level of oxidative stress markers - carbonyl groups, and nitrative products - 3-nitrotyrosine residues. The plasma lipid peroxidation was also investigated. The obtained results show that (1→3)-β-D-glucan inhibits in vitro ONOO(-)-induced oxidation and nitration of plasma proteins, even by 50% and 30%, respectively. The antioxidative activity of (1→3)-β-D-glucan was confirmed by its inhibitory effect on plasma lipids peroxidation induced by ONOO(-) or by H(2)O(2)., Conclusions: The obtained results demonstrate that (1→3)-β-D-glucan from S. cerevisiae protects plasma components against toxic effects of ONOO(-) and H(2)O(2) due to its antioxidative and antinitrative activities. Therefore (1→3)-β-D-glucan supplementation during inflammatory may be beneficial not only regard for its ability to stimulate the immune system but also by antioxidative properties., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Aronia melanocarpa fruits (Rosaceae) and grape seeds (seeds of Vitis vinifera, Vitaceae) are two of the richest plant sources of phenolic substances, and they have been shown to have various biological activities. The aim of the present study was to investigate and compare the action of phenolic extracts (at concentrations 5-100 µg/mL) of two different plants, berries of A. melanocarpa (chokebbery) and grape seeds, on the activities of various antioxidative enzymes, the amount of glutathione (as an important component of redox status) in control the platelets and platelets treated with H(2)O(2) (the strong physiological oxidant) in vitro. The properties of these two tested extracts were also compared with the action of a well characterized antioxidative and antiplatelet commercial monomeric polyphenol - resveratrol. The extract from berries of A. melanocarpa, like the extract from grape seeds, reduced the changes in activities of different antioxidative enzymes (glutathione peroxidase, superoxide dismutase, and catalase) in platelets treated with H(2)O(2). The action of the two tested plant extracts and H(2)O(2) evoked a significant increase of reduced glutathione in platelets compared with platelets treated with H(2)O(2) only. Comparative studies indicate that the two tested plant extracts had similar antioxidative properties, and were found to be more reactive in blood platelets than the solution of resveratrol.

The plant Humulus lupulus is known as the raw material of the brewing industry. Hop cones, rich in polyphenolic compounds and acyl phloroglucides, are widely used to preserve beer and to give it a characteristic aroma and flavor. Hop cones have long been used for medicinal purposes. In particular, hop preparations were mainly recommended for the treatment of sleeping disorders. The antioxidative action of hop cones, however, is poorly understood. The aim of our present study was to investigate in vitro changes in human blood platelets induced by peroxynitrite (ONOO(-), the compound of particular importance for vascular thrombosis and inflammatory process) in the presence of hop cone extract (Humulus lupulus). The antioxidative action of the extract was also compared with the properties of a well-characterized antioxidative commercial monomeric polyphenol, resveratrol (3,4',5-trihydroxystilbene) in a model system in vitro. Various biomarkers of oxidative/nitrative stress, such as carbonyl groups, 3-nitrotyrosine and thiobarbituric acid reactive substances (TBARS) were estimated. The 3-nitrotyrosine formation and carbonyl group generation was assessed by the use of a competition ELISA test and ELISA test, respectively. Tested plant extract (12.5-50 µg/ml), like resveratrol, significantly inhibited protein carbonylation and nitration in the blood platelets treated with ONOO(-) (0.1 mM). The extract from hop cones, like resveratrol, also caused a distinct reduction of platelet lipid peroxidation induced by ONOO(-). The present results indicate that the hope cone extract has in vitro protective effects against ONOO(-), such as induced oxidative/nitrative damage to the human platelet proteins and lipids. However, in comparative studies the extract was not found to be a more effective antioxidant than the solution of pure resveratrol.

The present in vitro study was designed to estimate the antioxidative activity of curcumin in the protection of human blood platelets and plasma against peroxynitrite (ONOO(-))-induced oxidative stress. The effects of curcumin (12.5-50 µg/ml) on ONOO(-)-induced damage of proteins and lipids were determined by the estimation of protein carbonyl groups, 3-nitrotyrosine formation, and thiobarbituric acid reactive substance (TBARS) generation. Exposure of blood platelets and plasma to 100 µM ONOO(-) resulted in an increased level of carbonyl groups, nitration of protein tyrosine residues, and enhanced lipid peroxidation. Curcumin inhibited carbonyl group formation in plasma and in platelet proteins. The highest dose of curcumin (50 µg/ml) reduced blood platelet protein carbonylation by approximately 40%. In the protection of blood plasma protein, the lower doses of curcumin (12.5 and 25 µg/ml) were more effective. Curcumin partially prevented 3-nitrotyrosine formation in plasma proteins; the effect of curcumin was only statistically significant in blood platelets at the highest dose (50 µg/ml). The antioxidative action of curcumin in the protection against lipid peroxidation caused by ONOO(-) was also observed. Curcumin suppressed the formation of TBARS both in blood platelets and in plasma samples. The highest concentration of curcumin (50 µg/ml) decreased the TBARS level by approximately 35% in both blood platelets and plasma samples. In conclusion, the present study demonstrates the antioxidative properties of curcumin and its protective effects against oxidative/nitrative changes of blood platelets and plasma components, especially proteins and lipids.

Lots of plants belonging to Asteraceae family are very popular in folk medicine in Poland. These plants are also known as being rich in acidic polysaccharides, due to the presence of hexuronic acids or its derivatives. Our preliminary experiments have shown that the extract from Conyza canadensis L. possesses various biological activity, including antiplatelet, antiocoagulant and antioxidant properties. The aim of our study was to assess if macromolecular glycoconjugates from selected herbal plants of Asteraceae family: Achillea millefolium L., Arnica montana L., Echinacea purpurea L., Solidago virgaurea L., Chamomilla recutita (L.) Rauschert., and Conyza canadensis L. protect platelet proteins against nitrative and oxidative damage induced by peroxynitrite, which is responsible for oxidative/nitrative modifications of platelet proteins: the formation of 3-nitrotyrosine and carbonyl groups. These modifications may lead to changes of blood platelet functions and can have pathological consequences. The role of these different medicinal plants in the defence against oxidative/nitrative stress in human platelets is still unknown, therefore the oxidative damage to platelet proteins induced by peroxynitrite and protectory effects of tested conjugates by the estimation of carbonyl group level and nitrotyrosine formation (a marker of protein nitration) were studied in vitro. The antioxidative properties of the polyphenolic-polysaccharide conjugates from selected tested medicinal plants were also compared with the action of a well characterized antioxidative commercial polyphenol - resveratrol (3,4',5-trihydroxystilbene). The obtained results demonstrate that the compounds from herbal plants: A. millefolium, A. montana, E. purpurea, C. recutita, S. virgaurea, possess antioxidative properties and protect platelet proteins against peroxynitrite toxicity in vitro, similar to the glycoconjugates from C. canadensis. However, in the comparative studies, the polyphenolic-polysaccharide conjugates from selected tested medicinal plants were not found to be more effective antioxidant, than the solution of pure resveratrol., (Published by Elsevier B.V.)

The oxidative stress induced by acute exertion may interfere with blood platelet activation. The beneficial effect of L-carnitine (gamma-trimethylamino-beta-hydroxybutyric acid) on oxidative stress in blood platelets has not been fully investigated; however, different studies indicate that this compound modulates platelet functions. The aim of our study was to assess the effects of L-carnitine on platelet activation and oxidative/nitrative protein damage (determined by the levels of protein carbonyl groups, thiol groups, and 3-nitrotyrosine residues) in resting blood platelets or platelets treated with peroxynitrite (ONOO(-), a strong physiological oxidant) in vitro. We also investigated the effects of L-carnitine on the level of platelet glutathione and on the formation of superoxide anion radicals O2(-*), lipid peroxidation measured by thiobarbituric acid reactive substances (TBARS) in blood platelets stimulated by thrombin (a strong physiological agonist), and platelet aggregation induced by adenosine diphosphate (a strong physiological stimulator). We have observed that carnitine decreases platelet activation (measured by platelet aggregation, the generation of O2(-*), and TBARS production). Moreover, our results in vitro demonstrate that carnitine may protect against oxidation of thiol groups induced by ONOO(-). Thus, carnitine may have some protectory effects against oxidative changes induced in blood platelets.

The aim of our study was to estimate oxidative stress (by using different biomarkers of lipid peroxidation--isoprostanes and thiobarbituric acid reactive substances (TBARS)) in patients with invasive breast cancer, patients with benign breast diseases and in a control group. We observed a statistically increased level of TBARS in plasma and isoprostanes in urine of patients with invasive breast cancer in comparison with a control group. The concentration of tested biomarkers in plasma or urine from patients with invasive breast cancer was also higher than in patients with benign breast diseases. Moreover, the levels of tested markers in patients with benign breast diseases and in a control group did not differ. Considering the data presented in this study, we suggest that free radicals induce peroxidation of unsaturated fatty acid in patients with breast cancer.

Blood platelets in addition to their haemostatic role can function as inflammatory cells. The aim of our study was to assess if beta-D-glucan, the natural, very strong biological response modifier, may protect platelet proteins and lipids against oxidative/nitrative damages. The antioxidative activity of the beta-D-glucan, a known immunomodulator derived from the yeast cell walls of species such as Saccharomyces cerevisiae, on blood platelets treated with oxidants-peroxynitrite and hydroperoxide-was studied in vitro. The levels of different specific markers of oxidative stress, thiobarbituric acid reactive substances (TBARS), carbonyl groups and 3-nitrotyrosine (3-NT) were measured. Our studies showed that beta-glucan possesses significant defence properties against peroxynitrite or hydroperoxide induced lipid peroxidation. The level of TBARS was decreased by 80% at the highest dose of beta-glucan. In the presence of beta-glucan the distinct reduction of platelet protein oxidation was observed; the level of carbonyl groups was decreased by 50%. The results indicate that beta-glucan may also be effective in the protection against the nitrative action of peroxynitrite on platelet proteins, as in the presence of beta-glucan the level of 3-nitrotyrosine, measured by a competition-ELISA method, was diminished. The obtained in vitro results demonstrate that antiplatelet activity of beta-glucan from Saccharomyces cerevisiae is dependent on its antioxidative properties, and therefore beta-glucan supplementation may be beneficial in the prevention of excessive blood platelet activation-related diseases, such as cardiovascular or inflammatory diseases.

The normal hemostatic mechanisms consist of a balance between hemorrhage and thrombosis that is achieved through the interaction of the blood vessels, blood platelets, the coagulation and fibrinolytic factors. The vascular endothelium sustains the balance between prevention and stimulation of platelet activation, thrombogenesis and fibrinolysis and between vasoconstriction and vasodilatation. Endothelial dysfunction associated with different cardiovascular diseases is related to the local formation of reactive oxygen/nitrogen species, mainly peroxynitrite that is produced in a rapid reaction between nitric oxide and superoxide anion. Reactive oxygen/nitrogen species induce changes in the structure and function in hemostatic elements. Proteins and lipids are major initial targets in endothelial cells, blood platelets and plasma. Reaction of reactive oxygen species and nitrogen species, including peroxynitrite, with cellular proteins can lead to nitration of aromatic amino acid residues, oxidation of thiol groups and conversion of some amino acid residues into carbonyl derivative. Oxidative/nitrative modifications of platelet proteins may induce changes of their signaling and haemostatic function (activation). Peroxynitrite also causes oxidation and nitration of fibrinogen--a key protein in coagulation cascade and plasminogen (the main protein of fibrinolysisprocess) changing their hemostatic functions. Oxidative/nitrative modifications of different components of haemostasis system have been observed in several cardiovascular diseases.

Since mechanisms involved in the relationship between oxidative stress and breast cancer are still unclear, the aim of our present study was to evaluate oxidative/nitrative modifications of blood platelet proteins by measuring the level of biomarkers of oxidative/nitrative stress such as carbonyl groups, thiol groups and 3-nitrotyrosine in proteins in patients with benign breast diseases and in patients with invasive breast cancer, and compare with the control group. Levels of carbonyl groups and 3-nitrotyrosine residues in platelet proteins were measured by ELISA and a competition ELISA, respectively. The method with 5,5′-dithio-bis(2-nitro-benzoic acid) has been used to analyse free thiol groups in platelet proteins. Patients were hospitalized in the Department of Oncological Surgery, Medical University of Lodz, Poland. Exogenous antioxidants reduce oxidative stress, therefore we also investigated in a model system in vitro the effects of a polyphenol rich extract of Aronia melanocarpa (Rosaceae, final concentration of 50 µg/ml, 5 min, 37°C) on modified blood platelet proteins as well from patients with breast cancer and from the healthy group. We demonstrated in platelet proteins from patients with invasive breast cancer a higher level of carbonyl groups than in the control healthy group (p < 0.02). The level of 3-nitrotyrosine in platelet proteins from patients with invasive breast cancer was also significantly higher than in the healthy subject group (p < 0.001). In contrast, the amount of thiol groups in platelet proteins from patients was significantly lower (about < 50%) than in control blood platelets. In a model system in vitro we also observed that the extract from berries of A. melanocarpa (50 µg/ml, 5 min, 37°C) due to antioxidant action, significantly reduced the oxidative/nitrative stress (measured by thiol groups and 3-nitrotyrosine) in platelets, not only from the healthy group, but also from patients with benign breast diseases and in patients with invasive breast cancer.

The effects of the beta-D-glucan, a polysaccharide derived from the yeast cell walls of species such as Saccharomyces cerevisiae, on blood platelets activation induced by physiological agonists (thrombin, ADP, collagen) in vitro were studied. The aim of our study was to assess in vitro if beta-glucan, a naturally strong biological response modifier, may modify platelet activation, i.e. platelet aggregation and degranulation (release of proteins and adenine nucleotides) induced by thrombin, ADP and collagen. Cytochrome c reduction method was used to test the ability of beta-glucan to change superoxide anion generation in platelets. Moreover, we determined also its effect on enzymatic arachidonic acid cascade. The obtained results indicate that beta-glucan has the inhibitory effects on platelet aggregation and secretion. beta-glucan distinctly reduced the arachidonic acid pathway and superoxide anion radical generation in platelets stimulated by biological agonists. The results of the present study suggest that beta-glucan from Saccharomyces cerevisiae has antiplatelet and antioxidative activities, and therefore may be beneficial in the prevention of the excessive blood platelet activation-related diseases, such as cardiovascular or inflammatory diseases.

Bioactive substances found in numerous foods can be successfully and safely used to modify various cellular functions and affect the oxidative stress. Aronia melanocarpa fruits (Rosaceae) are one of the richest plant sources of phenolic substances shown to have anti-inflammatory, antitumor, antioxidative and antiplatelet activities. We investigated antioxidant properties of the extract from berries of A. melanocarpa by the estimation of the selected and other biomarkers of oxidative stress, i.e. the level of 8-epi-prostaglandin F(2) (8-EPI) (by immunoassay kit) and the amount of glutathione (by HPLC method) in control platelets and platelets treated with H(2)O(2). The expression of alpha(IIb)beta(3) (a marker of platelet activation) was measured by flow cytometer. The antioxidative and antiplatelet properties of the tested extract were also compared with the action of a well characterized antioxidative and antiplatelet commercial monomeric polyphenol-resveratrol. The extract from berries of A. melanocarpa (at the highest tested concentration -100 microg/ml) decreased the production of 8-EPI (a marker of lipid peroxidation) in control blood platelets and platelets treated with H(2)O(2) (2 mM). A combined action of the tested plant extract and H(2)O(2) evoked a significant increase of reduced form of glutathione in platelets compared with cells treated with H(2)O(2) only. Moreover, the tested plant extract (at the highest used concentration -100 microg/ml) reduced the expression of alpha(IIb)beta(3) on blood platelets. Comparative studies indicate that the tested plant extract was found to be more reactive in blood platelets than the solution of pure resveratrol.