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Platelet aggregation is a complicated process mediated by different signaling pathways. As the process is highly complex and apparently redundant, the relationships between these pathways are not yet fully known. The aim of this project was to study the interconnections among seven different aggregation pathways in a group of 53 generally healthy volunteers aged 20 to 66 years. Platelet aggregation was induced with thrombin receptor activating peptide 6 (TRAP), arachidonic acid (AA), platelet activating factor 16 (PAF), ADP, collagen, thromboxane A 2 analogue U46619 or ristocetin (platelet agglutination) ex vivo in fasting blood samples according to standardized timetable protocol. Additionally, some samples were pre-treated with known clinically used antiplatelet drugs (vorapaxar, ticagrelor or acetylsalicylic acid (ASA)). Significant correlations among all used inducers were detected (Pearson correlation coefficients (r P ): 0.3 to 0.85). Of all the triggers, AA showed to be the best predictor of the response to other inducers with r P ranging from 0.66 to 0.85. Interestingly, the antiplatelet response to ticagrelor strongly predicted the response to unrelated drug vorapaxar (r P  = 0.71). Our results indicate that a response to one inducer can predict the response for other triggers or even to an antiplatelet drug. These data are useful for future testing but should be also confirmed in patients.

Vitamin B 12 , cobalamin, is indispensable for humans owing to its participation in two biochemical reactions: the conversion of l-methylmalonyl coenzyme A to succinyl coenzyme A, and the formation of methionine by methylation of homocysteine. Eukaryotes, encompassing plants, fungi, animals and humans, do not synthesise vitamin B 12 , in contrast to prokaryotes. Humans must consume it in their diet. The most important sources include meat, milk and dairy products, fish, shellfish and eggs. Due to this, vegetarians are at risk to develop a vitamin B 12 deficiency and it is recommended that they consume fortified food. Vitamin B 12 behaves differently to most vitamins of the B complex in several aspects, e.g. it is more stable, has a very specific mechanism of absorption and is stored in large amounts in the organism. This review summarises all its biological aspects (including its structure and natural sources as well as its stability in food, pharmacokinetics and physiological function) as well as causes, symptoms, diagnosis (with a summary of analytical methods for its measurement), prevention and treatment of its deficiency, and its pharmacological use and potential toxicity.

Background and Aims: It is well known that elevated cholesterol is associated with enhanced platelet aggregation and patients suffering from familial hypercholesterolemia (FH) have a high risk of thrombotic cardiovascular events. Although decreasing cholesterol level is associated with attenuation of platelet hyperactivity, there are currently no data on the effect of convertase subtilisin/kexin type 9 monoclonal antibodies (PCSK9ab) on platelet reactivity in FH. The aim of the study was to analyse the impact of different therapies including PCSK9ab on platelet aggregation in FH., Methods: This study enrolled all 15 patients treated in the University Hospital Hradec Králové for FH. PCSK9ab have been administered in 12 of 15 patients while 8 patients were also undergoing lipid apheresis. Blood samples from all patients including pre- and post-apheresis period were tested for platelet aggregation triggered by 7 inducers, and the effect of 3 clinically used drugs (acetylsalicylic acid, ticagrelor and vorapaxar) was compared as well., Results: Although apheresis decreased the reactivity of platelets in general, platelet responses were not different between non-apheresis patients treated with PCSK9ab and apheresis patients (post-apheresis values) with the exception of ristocetin. However, when compared to age-matched healthy population, FH patients had significantly lower platelet aggregation responses to 4 out of 7 used inducers and higher profit from 2 out of 3 used antiplatelet drugs even after exclusion of FH patients regularly receiving conventional antiplatelet treatment., Conclusion: This study showed for the first time the suitability of PCSK9ab treatment for reduction of platelet reactivity in FH patients., (© 2023. The Author(s).)

An imbalance in coagulation is associated with cardiovascular events. For prevention and treatment, anticoagulants, currently mainly xabans and gatrans, are used. The purpose of the present study was to provide a head-to-head comparison since there are no studies directly evaluating these novel anticoagulants. An additional aim was to find whether selected anthropological and biochemical factors can affect their anticoagulant properties as they are used in fixed doses. In this cross-sectional study, blood from 50 generally healthy donors was collected, and coagulation responses to dabigatran, argatroban, rivaroxaban, and apixaban, at a concentration of 1 μM, were analyzed. Heparin was used as a positive control. Prothrombin time (PT) expressed as international normalized ratio (INR) and activated partial thromboplastin time (aPTT) were measured and compared. Rivaroxaban was the most active according to PT/INR while argatroban according to aPTT. The ex vivo anticoagulant effect measured by INR correlated inversely with body mass index (BMI) in all four anticoagulants tested. Shortening of aPTT was associated with higher cholesterol and triglyceride levels. No sex-related differences were observed in response to the anticoagulant treatments. As this was an ex vivo study and pharmacokinetic factors were not included, the influence of BMI is of high therapeutic importance., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Concentrations of neopterin, kynurenine and kynurenine/tryptophan ratios predict prognosis and the need for oxygen therapy in patients hospitalized for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The aims of the present study were to evaluate the changes of these biomarkers early in the course of infection, the association with the prior coronavirus disease (COVID-19) vaccination and therapeutic administration of Anti-SARS-CoV-2 monoclonal antibodies, investigation of other potential biomarkers including neuropilin, 8-hydroxy-2-deoxyguanosine and 8-hydroxyguanosine in patients hospitalized with SARS-CoV-2 infection and an assessment of these biomarkers and vitamins A, E and D in patients with post-COVID syndrome., Methods: Urine and blood samples were obtained on the 1st to the 4th day and 4th to 7th day from 108 patients hospitalized with COVID-19. Chromatography tandem mass spectrometry methods were used to analyse neopterin, kynurenine, tryptophan, liposoluble vitamins, and DNA damage biomarkers., Results: A statistically significant decrease of neopterin, kynurenine and kynurenine/tryptophan ratios was observed on after 4th to 7th day of hospitalization, and concentrations of these biomarkers were increased in patients with poor prognosis and subsequent post-COVID syndrome. The concentrations of remaining biomarker and vitamins were not associated with outcomes, although markedly decreased concentrations of vitamin A, E and D were noted., Conclusions: The concentrations of neopterin, kynurenine and kynurenine/tryptophan ratios decrease during the course of infection SARS-CoV-2 and are associated with the post-COVID syndrome. No other prognostic biomarkers were identified., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Determination of the various forms of vitamin K, which are involved in coagulation and other physiological processes in humans, is challenging and no standardized method is yet available. Therefore, a reliable and practical method was developed to quantify vitamin K levels in serum and additionally in lipoprotein fractions to clarify its distribution. The LC-MS/MS method for the determination of vitamin K 1 and the three main isoforms of vitamin K 2 (MK-4, MK-7, MK-9) was combined with a gradient ultracentrifugation technique to allow the separation of lipoprotein fractions. The chromatographic separation was carried out on a Kinetex™ C18 column using a mobile phase consisting mainly of methanol. The target analytes were detected by electrospray ionization mass spectrometry. The separation of all four substances was achieved after a simple sample preparation technique based on miniaturized liquid-liquid extraction. Our method of only 8.5 min revealed the levels of the major forms of vitamin K in 59 human and 12 rat sera and confirmed our hypothesis that vitamin K is primarily (about 50 %) found in the high-density lipoprotein fraction. The median concentrations of vitamin K 1 , MK-4, MK-7, and MK-9 were found to be 1.19, 2.98, 0.43, and < 0.71 nmol/L in human serum and 1.74, 6.75, less than 0.2, and less than 0.5 nmol/L in rat serum, respectively., Competing Interests: Declaration of Competing Interest 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., (Copyright © 2023 Elsevier B.V. All rights reserved.)

At the turn of the millennium, the monolithic columns invoked new chances in HPLC. Even more than their organic polymer-based siblings, the inorganic silica-based monoliths targeted the territory of classical fully porous particle-packed columns, promising many benefits. Based on the number of published articles, the monoliths attracted academics just in the first few years after their introduction to the market. Lately, as superficially porous particles and sub-2-micron fully porous particles dominated the market, they stayed in the focus of routine laboratories and those who really appreciated the high porosity of the monolithic bed. The monoliths' practical benefits cannot be easily traced in the literature when they gradually lose academics' interest. Nevertheless, after more than 20 years of our experience, we still favor silica monoliths for their low back pressure and longevity when analyzing samples of clinical, pharmaceutical, and environmental origin. At the same time, the high permeability of monoliths enabled the birth of sequential injection chromatography, the medium-pressure separation technique based on the flexible flow manifold. This minireview aims to check, discuss, and summarize the practical aspects of monolithic silica columns in HPLC and medium-pressure sequential injection chromatography (SIC) that may not be visible at first sight but are evident retrospectively., (© 2023 The Authors. Journal of Separation Science published by Wiley-VCH GmbH.)

The process of platelet aggregation is often influenced by several factors including sex and age. A literature review confirmed the existence of sex-related differences in platelet aggregation. Although 68 out of 78 papers found such differences, there are still some controversies regarding these differences, which can be due to multiple factors (age, trigger, concomitant disease, sample handling, etc.). These outcomes are discussed in line with novel results obtained from a local study, in which blood samples from a total of 53 overall healthy women and men with ages ranging from 20 to 66 years were collected. Aggregation was induced with seven different triggers (ristocetin, thrombin receptor activating peptide 6 [TRAP-6], arachidonic acid [AA], platelet-activating factor 16 [PAF-16], ADP, collagen, or thromboxane A 2 analog U-46619) ex vivo. In addition, three FDA-approved antiplatelet drugs (vorapaxar, ticagrelor, or acetylsalicylic acid [ASA]) were also tested. In general, women had higher aggregation responses to some agonists (ADP, TRAP), as well as lower benefit from inhibitors (ASA, vorapaxar). The aggregatory responses to AA and TRAP decreased with age in both sexes, while responses to ADP, U-46619, and PAF were affected by age only in women. In conclusion, more studies are needed to decipher the biological importance of sex-related differences in platelet aggregation in part to enable personalized antiplatelet treatment., Competing Interests: None declared., (Thieme. All rights reserved.)

A novel ultra-high performance chromatography method with multichannel detection that allows fast, sensitive, and robust analysis of an antifungal drug terbinafine and its three main impurities β-terbinafine, ( Z )-terbinafine, and 4-methylterbinafine in just 5.0 min has been developed. Analysis of terbinafine is important in pharmaceutical analysis since it enables the detection of its impurities at very low concentrations. In this study, we focused on the development, optimization, and validation of the UHPLC method as well as its subsequent application in the evaluation of terbinafine and its three main impurities in the dissolution medium to reveal the incorporation of terbinafine in two poly(lactic- co -glycolic acid) (PLGA) carriers and testing of the drug release at pH 5.5. PLGA based drug delivery systems such as solid dispersions, thin films, microparticles, and nanoparticles are new favorable ways of terbinafine administration. PLGA features excellent tissue compatibility, biodegradation, and adjustable drug release profile. Our pre-formulation study indicates that poly(acrylic acid) branched PLGA polyester has more suitable properties than tripentaerythritol branched PLGA polyester. Therefore, the former is likely to enable design of a new drug delivery system for topically applied terbinafine that could facilitate its administration and increase patient compliance.

Objectives: Currently, no biomarker or scoring system could clearly identify patients at risk of progression to a severe coronavirus disease (COVID)-19. Even in patients with known risk factors, the fulminant course cannot be predicted with certainty. Analysis of commonly determined clinical parameters (frailty score, age, or body mass index) together with routine biomarkers of host response (C-reactive protein and viral nucleocapsid protein) in combination with new biomarkers neopterin, kynurenine, and tryptophan, could aid in predicting the patient outcome., Methods: In 2021 and 2022, urine and serum samples were prospectively collected on 1st to 4th day after hospital admission in 108 consecutive COVID-19 patients hospitalized at the University Hospital Hradec Králové, Czech Republic. Delta and omicron virus variants were studied. Neopterin, kynurenine and tryptophan were determined by liquid chromatography., Results: A significant correlation was observed between urinary and serum biomarker concentrations. Urinary and serum neopterin, kynurenine and kynurenine/tryptophan ratio were significantly (p≤0.05) higher in patients who subsequently needed oxygen therapy vs. patients without oxygen therapy. These parameters were also significantly increased in patients who died during the hospitalization compared to survivors. Complex equations have been derived using the investigated biomarkers and other clinical or laboratory parameters to predict the risk of subsequent oxygen therapy or death during hospitalization., Conclusions: Present data demonstrate that neopterin, kynurenine and kynurenine/tryptophan ratio in the serum or in the urine represent promising biomarkers in the management of COVID-19 that may help to guide important therapeutic decisions., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Elevated low-density lipoprotein (LDL) cholesterol levels lead to atherosclerosis and platelet hyperaggregability, both of which are known culprits of arterial thrombosis. Normalization of LDL cholesterol in familial hypercholesterolemia (FH) is not an easy task and frequently requires specific treatment, such as regularly performed lipid apheresis and/or novel drugs such as proprotein convertase subtilisin kexin 9 monoclonal antibodies (PCSK9Ab). Moreover, a high resistance rate to the first-line antiplatelet drug acetylsalicylic acid (ASA) stimulated research of novel antiplatelet drugs. 4-methylcatechol (4-MC), a known metabolite of several dietary flavonoids, may be a suitable candidate. The aim of this study was to analyse the antiplatelet effect of 4-MC in FH patients and to compare its impact on two FH treatment modalities via whole-blood impedance aggregometry. When compared to age-matched, generally healthy controls, the antiplatelet effect of 4-MC against collagen-induced aggregation was higher in FH patients. Apheresis itself improved the effect of 4-MC on platelet aggregation and blood from patients treated with this procedure and pretreated with 4-MC had lower platelet aggregability when compared to those solely treated with PCKS9Ab. Although this study had some inherent limitations, e.g., a low number of patients and possible impact of administered drugs, it confirmed the suitability of 4-MC as a promising antiplatelet agent and also demonstrated the effect of 4-MC in patients with a genetic metabolic disease for the first time.

A polyphenol-rich diet has beneficial effects on cardiovascular health. However, dietary polyphenols generally have low bioavailability and reach low plasma concentrations. Small phenolic metabolites of these compounds formed by human microbiota are much more easily absorbable and could be responsible for this effect. One of these metabolites, 4-methylcatechol (4-MC), was suggested to be a potent anti-platelet compound. The effect of 4-MC was tested ex vivo in a group of 53 generally healthy donors using impedance blood aggregometry. The mechanism of action of this compound was also investigated by employing various aggregation inducers/inhibitors and a combination of aggregometry and enzyme linked immunosorbent assay (ELISA) methods. 4-MC was confirmed to be more potent than acetylsalicylic acid on both arachidonic acid and collagen-triggered platelet aggregation. Its clinically relevant effect was found even at a concentration of 10 μM. Mechanistic studies showed that 4-MC is able to block platelet aggregation caused by the stimulation of different pathways (receptors for the von Willebrand factor and platelet-activating factor, glycoprotein IIb/IIIa, protein kinase C, intracellular calcium elevation). The major mechanism was defined as interference with cyclooxygenase-thromboxane synthase coupling. This study confirmed the strong antiplatelet potential of 4-MC in a group of healthy donors and defined its mechanism of action.

This review summarizes the current knowledge on essential vitamins B 1 , B 2 , B 3 , and B 5 . These B-complex vitamins must be taken from diet, with the exception of vitamin B 3 , that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B 3 , is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

Background and Aims: Enhanced recovery after surgery (ERAS) is currently the modern perioperative method of care for improvement of post-surgery patient condition and for minimising various postoperative complications. A question of some negative impact of early postoperative parenteral nutrition on postoperative inflammatory response intensity has not clear-cut answer yet. This pilot project was focused on the possible influence of early parenteral nutrition on the intensity of inflammatory postoperative response to operating trauma in surgical patients. Elected as a model of these conditions were patients with colorectal cancer undergoing major surgery., Patients and Methods: 45 patients (of whom 39 were analysed finally) operated for cancer of the large bowel were enrolled into the clinical, prospective, randomized, blinded, and monocentric trial - reference number 201811 S09P of the Ethics committee, University Hospital Hradec Kralove, Czech Republic. Patients were divided into two subgroups according to the type of nutrition: subgroup A - supplemented only with 10% glucose for supported mineral carrier; and subgroup B - supplemented with total parenteral nutrition. Samples of blood and urine were examined immediately after surgery, and on the first, second, and fourth days postoperatively. The inflammatory reaction was monitored by the serum or/and urine concentration of neopterin, tryptophan, and kynurenine, and their urinary ratios with creatinine. The results were analysed by multivariate analysis, and p-values ≤ 0.05 were considered statistically significant., Results: The final total of 39 patients comprised 20 from subgroup A and 19 from subgroup B. The intensity of the inflammatory response detected by the selected inflammatory markers (serum and urine concentrations of neopterin, kynurenine, tryptophan, their serum ratios, and their urinary ratios to creatinine) did not demonstrate statistically significant differences after early administration of the two alternative types of parenteral nutrition., Conclusions: The results of the study demonstrated the same or a very similar impact on the intensity of postoperative inflammatory response, regardless of whether the patient received intravenous administration of a small simple sugar infusion or total parenteral nutrition during early postoperative care., Competing Interests: Declaration of competing interest The authors state that they are no conflicts of interest regarding the publication of this article., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Vitamin A is a group of vital micronutrients widely present in the human diet. Animal-based products are a rich source of the retinyl ester form of the vitamin, while vegetables and fruits contain carotenoids, most of which are provitamin A. Vitamin A plays a key role in the correct functioning of multiple physiological functions. The human organism can metabolize natural forms of vitamin A and provitamin A into biologically active forms (retinol, retinal, retinoic acid), which interact with multiple molecular targets, including nuclear receptors, opsin in the retina and, according to the latest research, also some enzymes. In this review, we aim to provide a complex view on the present knowledge about vitamin A ranging from its sources through its physiological functions to consequences of its deficiency and metabolic fate up to possible pharmacological administration and potential toxicity. Current analytical methods used for its detection in real samples are included as well.