Sensitive and label-free SPR biosensing platforms for high-throughput screening of plasma membrane receptors interactions with insulin-like targets of hypoglycaemic activity

Progress in medical sciences aims for tailored therapy of civilization diseases like diabetes. Preclinical screening of new medicines superior to insulin should include the verification of their affinity to the membrane receptors naturally stimulated by this hormone: insulin receptor isoforms A and B and insulin-like growth factor receptor. Considering that the affinity constants obtained using different experimental conditions are incomparable, it is essential to develop a robust and reliable method to analyze these interactions. The versatile SPR platform developed in this study enables the evaluation of the bioactivity of hypoglycaemic molecules. Thanks to the comprehensive characterization of miscellaneous aspects of the analytical platform, including the design of the SPR biosensor receptor layer, ensuring interaction specificity, as well as the quality control of the standards used (human insulin, HI; long-acting insulin analog: glargine, Gla), the feasibility of the method of equilibrium and kinetic constants determination for insulin-like targets was confirmed. SPR assays constructed in the direct format using IR-A, IR-B, and IGF1-R receptor proteins show high sensitivities and low detection limits towards insulin and glargine detection in the range of 18.3-53.3 nM with no signs of mass transport limitations. The improved analytical performance and stability of SPR biosensors favor the acquisition of good-quality kinetic data, while preservation of receptors activity after binding to long-chain carboxymethyldextran, combined with spontaneous regeneration, results in stability and long shelf life of the biosensor, which makes it useful for label-free insulin analogs biosensing and thus extensive screening in diabetic drugs discovery.

A Careful Insight into DDI-Type Receptor Layers on the Way to Improvement of Click-Biology-Based Immunosensors

Protein-based microarrays are important tools for high-throughput medical diagnostics, offering versatile platforms for multiplex immunodetection. However, challenges arise in protein microarrays due to the heterogeneous nature of proteins and, thus, differences in their immobilization conditions. This article advocates DNA-directed immobilization (DDI) as a solution, emphasizing its rapid and cost-effective fabrication of biosensing platforms. Thiolated single-stranded DNA and its analogues, such as ZNA® and PNA probes, were used to immobilize model proteins (anti-CRP antibodies and SARS-CoV nucleoprotein). The study explores factors influencing DDI-based immunosensor performance, including the purity of protein-DNA conjugates and the stability of their duplexes with DNA and analogues. It also provides insight into backfilling agent type and probe surface density. The research reveals that single-component monolayers lack protection against protein adsorption, while mixing the probes with long-chain ligands may hinder DNA-protein conjugate anchoring. Conventional DNA probes offer slightly higher surface density, while ZNA® probes exhibit better binding efficiency. Despite no enhanced stability in different ionic strength media, the cost-effectiveness of DNA probes led to their preference. The findings contribute to advancing microarray technology, paving the way for new generations of DDI-based multiplex platforms for rapid and robust diagnostics.

Quantum dots-based "chemical tongue" for the discrimination of short-length Aβ peptides

A "chemical tongue" is proposed based on thiomalic acid-capped quantum dots (QDs) with signal enrichment provided by excitation-emission matrix (EEM) fluorescence spectroscopy for the determination of close structural analogs-short-length amyloid β (Aβ) peptides related to Alzheimer's disease. Excellent discrimination is obtained by principal component analysis (PCA) for seven derivatives: Aβ1-16, Aβ4-16, Aβ4-9, Aβ5-16, Aβ5-12, Aβ5-9, Aβ12-16. Detection of Aβ4-16, Aβ4-16, and Aβ5-9 in binary and ternary mixtures performed by QDs-based chemical tongue using partial least squares-discriminant analysis (PLS-DA) provided perfect 100% accuracy for the two studied peptides (Aβ4-16 and Aβ4-16), while for the third one (Aβ5-9) it was slightly lower (97.9%). Successful detection of Aβ4-16 at 1 pmol/mL (1.6 ng/mL) suggests that the detection limit of the proposed method for short-length Aβ peptides can span nanomolar concentrations. This result is highly promising for the development of simple and efficient methods for sequence recognition in short-length peptides and better understanding of mechanisms at the QD-analyte interface.

Study on Saccharide-Glucose Receptor Interactions with the Use of Surface Plasmon Resonance

The aim of this study was to investigate the process of attachment of saccharide particles differing in degree of complexity to cell receptors responsible for transport of glucose across the cell membrane (GLUT proteins). This phenomenon is currently considered when designing modern medicines, e.g., peptide drugs to which glucose residues are attached, enabling drugs to cross the barrier of cell membranes and act inside cells. This study aims to help us understand the process of assimilation of polysaccharide nanoparticles by tumour cells. In this study, the interactions between simple saccharides (glucose and sucrose) and dextran nanoparticles with two species of GLUT proteins (GLUT1 and GLUT4) were measured using the surface plasmon resonance technique. We managed to observe the interactions of glucose and sucrose with both applied proteins. The lowest concentration that resulted in the detection of interaction was 4 mM of glucose on GLUT1. Nanoparticles were measured using the same proteins with a detection limit of 40 mM. These results indicate that polysaccharide nanoparticles interact with GLUT proteins. The measured strengths of interactions differ between proteins; thus, this study can suggest which protein is preferable when considering it as a mean of nanoparticle carrier transport.

Au-X (X=Pt/Ru)-decorated magnetic nanocubes as bifunctional nanozyme labels in colorimetric, magnetically-enhanced, one-step sandwich CRP immunoassay

Scientific interest in the investigation and application of multifunctional nanomaterials in medical diagnostics has been increasing. The employment of magnetocatalytic immunoconjugates as both analyte-capturing agents and enzyme-like catalytic labels may enable rapid preconcentration and determination of relevant antigens. In this work, we synthesized and comprehensively characterized two types of noble metal-decorated magnetic nanocubes (MDMCs) which were subsequently applied in the one-step, sandwich nanozyme-linked immunosorbent assay (NLISA). Magnetic cores allow for rapid separation from complex samples of biological origin. The catalytically active shell composed of Au-decorated Pt or Ru can effectively mimic the activity of horseradish peroxididase, retaining at the same time the ability to form stable bioconstructs through self-assembly of thiolated ligands. As a result, hybrid multifunctional nanoparticles were synthesized and used to detect C-reactive protein (CRP) in serum samples. We have also paid considerable attention to the mechanistic studies of the formation of sandwich immunocomplexes with nanoparticle labels by means of immunoenzymatic methods and surface plasmon resonance. Analytical parameters of the Pt-MDMCs-labeled NLISA (detection limit LOD = 0.336 ng mL-1, recovery = 98.0%, linear response window covering two logarithmic units) turned out to be superior to the classical, one-step ELISA based on a horseradish peroxidase. In addition, our method offers further possibility of sensitivity adjustment by changing the parameters of magnetic preconcentration, together with good long-term stability of MDMCs conjugates and their good resistance to common interferences. We believe that the proposed simple synthetic protocol will guide a new approach to applying metal-decorated magnetic nanozymes as versatile and multifunctional labels for application in subsequent pre-analytical analyte concentration and immunoassays towards clinical applications.

Portable Surface Plasmon Resonance Detector for COVID-19 Infection

Methods based on nucleic acid detection are currently the most commonly used technique in COVID-19 diagnostics. Although generally considered adequate, these methods are characterised by quite a long time-to-result and the necessity to prepare the material taken from the examined person-RNA isolation. For this reason, new detection methods are being sought, especially those characterised by the high speed of the analysis process from the moment of sampling to the result. Currently, serological methods of detecting antibodies against the virus in the patient's blood plasma have attracted much attention. Although they are less precise in determining the current infection, such methods shorten the analysis time to several minutes, making it possible to consider them a promising method for screening tests in people with suspected infection. The described study investigated the feasibility of a surface plasmon resonance (SPR)-based detection system for on-site COVID-19 diagnostics. A simple-to-use portable device was proposed for the fast detection of anti-SARS-CoV-2 antibodies in human plasma. SARS-CoV-2-positive and -negative patient blood plasma samples were investigated and compared with the ELISA test. The receptor-binding domain (RBD) of spike protein from SARS-CoV-2 was selected as a binding molecule for the study. Then, the process of antibody detection using this peptide was examined under laboratory conditions on a commercially available SPR device. The portable device was prepared and tested on plasma samples from humans. The results were compared with those obtained in the same patients using the reference diagnostic method. The detection system is effective in the detection of anti-SARS-CoV-2 with the detection limit of 40 ng/mL. It was shown that it is a portable device that can correctly examine human plasma samples within a 10 min timeframe.

Red Flags and Adversities on the Way to the Robust CE-ICP-MS/MS Quantitative Monitoring of Self-Synthesized Magnetic Iron Oxide(II, III)-Based Nanoparticle Interactions with Human Serum Proteins

The growing interest in superparamagnetic iron oxide nanoparticles (SPIONs) as potential theranostic agents is related to their unique properties and the broad range of possibilities for their surface functionalization. However, despite the rapidly expanding list of novel SPIONs with potential biomedical applications, there is still a lack of methodologies that would allow in-depth investigation of the interactions of those nanoparticles with biological compounds in human serum. Herein, we present attempts to employ capillary electrophoresis-inductively coupled plasma tandem mass spectrometry (CE-ICP-MS/MS) for this purpose and various obstacles and limitations noticed during the research. The CE and ICP-MS/MS parameters were optimized, and the developed method was used to study the interactions of two different proteins (albumin and transferrin) with various synthesized SPIONs. While the satisfactory resolution between proteins was obtained and the method was applied to examine individual reagents, it was revealed that the conjugates formed during the incubation of the proteins with SPIONs were not stable under the conditions of electrophoretic separation.

Comparative Evaluation of Different Surface Coatings of Fe3O4-Based Magnetic Nano Sorbent for Applications in the Nucleic Acids Extraction

Nucleic acid extraction and purification are crucial steps in sample preparation for multiple diagnostic procedures. Routine methodologies of DNA isolation require benchtop equipment (e.g., centrifuges) and labor-intensive steps. Magnetic nanoparticles (MNPs) as solid-phase sorbents could simplify this procedure. A wide range of surface coatings employs various molecular interactions between dsDNA and magnetic nano-sorbents. However, a reliable, comparative evaluation of their performance is complex. In this work, selected Fe3O4 modifications, i.e., polyethyleneimine, gold, silica, and graphene derivatives, were comprehensively evaluated for applications in dsDNA extraction. A family of single batch nanoparticles was compared in terms of morphology (STEM), composition (ICP-MS/MS and elemental analysis), surface coating (UV-Vis, TGA, FTIR), and MNP charge (ζ-potential). ICP-MS/MS was also used to unify MNPs concentration allowing a reliable assessment of individual coatings on DNA extraction. Moreover, studies on adsorption medium (monovalent vs. divalent ions) and extraction buffer composition were carried out. As a result, essential relationships between nanoparticle coatings and DNA adsorption efficiencies have been noticed. Fe3O4@PEI MNPs turned out to be the most efficient nano sorbents. The optimized composition of the extraction buffer (medium containing 0.1 mM EDTA) helped avoid problems with Fe3+ stripping, which improved the validity of the spectroscopic determination of DNA recovery.

Interactions of proteins with metal-based nanoparticles from a point of view of analytical chemistry - Challenges and opportunities

Interactions of proteins with nanomaterials draw attention of many research groups interested in fundamental phenomena. However, alongside with valuable information regarding physicochemical aspects of such processes and their mechanisms, they more and more often prove to be useful from a point of view of bioanalytics. Deliberate use of processes based on adsorption of proteins on nanoparticles (or vice versa) allows for a development of new analytical methods and improvement of the existing ones. It also leads to obtaining of nanoparticles of desired properties and functionalities, which can be used as elements of analytical tools for various applications. Due to interactions with nanoparticles, proteins can also gain new functionalities or lose their interfering potential, which from perspective of bioanalytics seems to be very inviting and attractive. In the framework of this article we will discuss the bioanalytical potential of interactions of proteins with a chosen group of nanoparticles, and implementation of so driven processes for biosensing. Moreover, we will show both positive and negative (opportunities and challenges) aspects resulting from the presence of proteins in media/samples containing metal-based nanoparticles or their precursors.

Excitation-emission fluorescence matrix acquired from glutathione capped CdSeS/ZnS quantum dots in combination with chemometric tools for pattern-based sensing of neurotransmitters

The presented work concerns pattern-based sensing with quantum dots for the identification and quantification of neurotransmitters by means of excitation-emission fluorescence spectroscopy (2D fluorescence). In the framework of this study, glutathione capped CdSeS/ZnS nanocrystals were used as non-specific nanoreceptors capable of differentiated interaction with neurotransmitters. The pattern-based sensing with QDs was realized by using excitation-emission fluorescence spectroscopy to provide analyte-specific multidimensional optical information. These characteristic fluorescent response patterns were processed by unfolded partial least squares-discriminant analysis, showing that satisfactory identification of all investigated neurotransmitters: dopamine, norepinephrine, epinephrine, serotonin, GABA, and acetylcholine, can be achieved through the proposed sensing strategy. The impact of the considered fluorescence signal (datum, i.e. zeroth-order data acquired per sample; spectrum, i.e. first-order data acquired per sample; excitation-emission matrix, i.e. second-order data acquired per sample) on the sensing capability of glutathione capped QDs was also verified. The best performance parameters such as accuracy, precision, sensitivity, and specificity were obtained using excitation-emission matrices (88.9-93.3%, 0.93-0.95, 0.89-0.93, and 0.99-1.00, respectively). Thus, it was revealed that excitation-emission fluorescence spectroscopy may improve the recognition of neurotransmitters while using only one type of nanoreceptor. Furthermore, is was demonstrated that the proposed excitation-emission fluorescence spectroscopy assisted QD assay coupled with unfolded partial least squares regression can be successfully utilized for quantitative determination of catecholamine neurotransmitters at the micromolar concentration range with R2 in the range 0.916-0.987. Consequently, the proposed sensing strategy has the potential to significantly simplify the sensing element and to expand the pool of bioanalytes so far detectable with the use of QDs.

Recent Advancements in Receptor Layer Engineering for Applications in SPR-Based Immunodiagnostics

The rapid progress in the development of surface plasmon resonance-based immunosensing platforms offers wide application possibilities in medical diagnostics as a label-free alternative to enzyme immunoassays. The early diagnosis of diseases or metabolic changes through the detection of biomarkers in body fluids requires methods characterized by a very good sensitivity and selectivity. In the case of the SPR technique, as well as other surface-sensitive detection strategies, the quality of the transducer-immunoreceptor interphase is crucial for maintaining the analytical reliability of an assay. In this work, an overview of general approaches to the design of functional SPR-immunoassays is presented. It covers both immunosensors, the design of which utilizes well-known and often commercially available substrates, as well as the latest solutions developed in-house. Various approaches employing chemical and passive binding, affinity-based antibody immobilization, and the introduction of nanomaterial-based surfaces are discussed. The essence of their influence on the improvement of the main analytical parameters of a given immunosensor is explained. Particular attention is paid to solutions compatible with the latest trends in the development of label-free immunosensors, such as platforms dedicated to real-time monitoring in a quasi-continuous mode, the use of in situ-generated receptor layers (elimination of the regeneration step), and biosensors using recombinant and labelled protein receptors.

Iron deficiency contributes to resistance to endogenous erythropoietin in anaemic heart failure patients

AIMS

Abnormal endogenous erythropoietin (EPO) constitutes an important cause of anaemia in chronic diseases. We analysed the relationships between iron deficiency (ID) and the adequacy of endogenous EPO in anaemic heart failure (HF) patients, and the impact of abnormal EPO on 12-month mortality.

METHODS AND RESULTS

We investigated 435 anaemic HF patients (age: 74 ± 10 years; males: 60%; New York Heart Association class I or II: 39%; left ventricular ejection fraction: 43 ± 17%). Patients with EPO higher than expected for a given haemoglobin were considered EPO-resistant whereas those with EPO lower than expected - EPO-deficient. ID was defined as serum ferritin <100 µg/L or 100-299 µg/L with transferrin saturation <20%. EPO-resistant patients (22%) had more advanced HF whereas those with EPO deficiency (57%) were more frequently females and had worse renal function. Lower serum ferritin (indicating depleted body iron stores) was related to higher EPO observed/predicted ratio when adjusted for significant clinical confounders, including C-reactive protein. One year all-cause mortality was 28% in patients with EPO resistance compared to 17% in patients with EPO deficiency and 10% in patients with adequate EPO (log-rank test for the comparison EPO resistance vs. adequate EPO: P = 0.02). When adjusted for other prognosticators, there was still a trend towards increased 12-month mortality in patients with higher EPO level.

CONCLUSION

Anaemic HF patients with endogenous EPO deficiency vs. resistance have different clinical and laboratory characteristics. In such patients, ID contributes to EPO resistance independently of inflammation.

Primary Human Cardiomyocytes and Cardiofibroblasts Treated with Sera from Myocarditis Patients Exhibit an Increased Iron Demand and Complex Changes in the Gene Expression

Cardiac fibroblasts and cardiomyocytes are the main cells involved in the pathophysiology of myocarditis (MCD). These cells are especially sensitive to changes in iron homeostasis, which is extremely important for the optimal maintenance of crucial cellular processes. However, the exact role of iron status in the pathophysiology of MCD remains unknown. We cultured primary human cardiomyocytes (hCM) and cardiofibroblasts (hCF) with sera from acute MCD patients and healthy controls to mimic the effects of systemic inflammation on these cells. Next, we performed an initial small-scale (n = 3 per group) RNA sequencing experiment to investigate the global cellular response to the exposure on sera. In both cell lines, transcriptomic data analysis revealed many alterations in gene expression, which are related to disturbed canonical pathways and the progression of cardiac diseases. Moreover, hCM exhibited changes in the iron homeostasis pathway. To further investigate these alterations in sera-treated cells, we performed a larger-scale (n = 10 for controls, n = 18 for MCD) follow-up study and evaluated the expression of genes involved in iron metabolism. In both cell lines, we demonstrated an increased expression of transferrin receptor 1 (TFR1) and ferritin in MCD serum-treated cells as compared to controls, suggesting increased iron demand. Furthermore, we related TFR1 expression with the clinical profile of patients and showed that greater iron demand in sera-treated cells was associated with higher inflammation score (interleukin 6 (IL-6), C-reactive protein (CRP)) and advanced neurohormonal activation (NT-proBNP) in patients. Collectively, our data suggest that the malfunctioning of cardiomyocytes and cardiofibroblasts in the course of MCD might be related to alterations in the iron homeostasis.

Nanoparticles of chosen noble metals as reactive oxygen species scavengers

Reactive oxygen species (ROS) play an important role in various physiological processes of living organisms. However, their increased concentration is usually considered as a threat for our health. Plants, invertebrates, and vertebrates including humans have various enzymatic and non-enzymatic defence systems against ROS. Unfortunately, both bad condition of surrounding environment and unhealthy lifestyle can interfere with an activity of enzymes responsible for a regulation of ROS levels. Therefore, it is important to look for alternative ROS scavengers, which could be administrated to chosen tissues to prevent pathological processes such as distortion of DNA or RNA structures and oxidation of proteins and lipids. One of the most recently proposed solutions is the application of nanozymes, which could mimic the activity of essential enzymes and prevent excessive activity of ROS. In this work, nanoparticles of Au, Pt, Pd, Ru and Rh were synthesized and studied in this regard. Peroxidase-, catalase (CAT)- and superoxide dismutase (SOD)-like activity of obtained nanoparticles were tested and compared using different methods. The influence of bovine and human albumins on CAT- and peroxidase-like activity was examined. Moreover, in the case of CAT-like activity, an influence of pH and temperature was examined and compared. Determination of SOD-like activity using the methods described for the examination of the activity of native enzyme was not fully successful. Moreover, cytotoxicity of chosen nanoparticles was studied on both regular and tumor cells.

Frailty and the risk of all-cause mortality and hospitalization in chronic heart failure: a meta-analysis

To estimate the risk of all-cause mortality and hospitalization in frail patients with chronic heart failure (HF), a systematic search and meta-analysis was carried out to identify all prospective cohort studies conducted among adults with HF where frailty was quantified and related to the primary endpoints of all-cause mortality and/or hospitalization. Twenty-nine studies reporting the link between frailty and all-cause mortality in 18 757 patients were available for the meta-analysis, along with 11 studies, with 13 525 patients, reporting the association between frailty and hospitalization. Frailty was a predictor of all-cause mortality and hospitalization with summary hazard ratios (HRs) of 1.48 [95% confidence interval (CI): 1.31-1.65, P < 0.001] and 1.40 (95% CI: 1.27-1.54, P < 0.001), respectively. Summary HRs for all-cause mortality among frail inpatients undergoing ventricular assist device implantation, inpatients hospitalized for HF, and outpatients were 1.46 (95% CI: 1.18-1.73, P < 0.001), 1.58 (95% CI: 0.94-2.22, P = not significant), and 1.53 (95% CI: 1.28-1.78, P < 0.001), respectively. Summary HRs for all-cause mortality and frailty based on Fried's phenotype were 1.48 (95% CI: 1.03-1.93, P < 0.001) and 1.42 (95% CI: 1.05-1.79, P < 0.001) for inpatients and outpatients, respectively, and based on other frailty measures were 1.42 (95% CI: 1.12-1.72, P < 0.001) and 1.60 (95% CI: 1.43-1.77, P < 0.001) for inpatients and outpatients, respectively. Across clinical contexts, frailty in chronic HF is associated with an average of 48% and 40% increase in the hazard of all-cause mortality and hospitalization, respectively. The relationship between frailty and all-cause mortality is similar across clinical settings and comparing measurement using Fried's phenotype or other measures.

Iron status, catabolic/anabolic balance, and skeletal muscle performance in men with heart failure with reduced ejection fraction

BACKGROUND

Metabolic derangements related to tissue energetics constitute an important pathophysiological feature of heart failure. We investigated whether iron deficiency and catabolic/anabolic imbalance contribute to decreased skeletal muscle performance in men with heart failure with reduced ejection fraction (HFrEF), and whether these pathologies are related to each other.

METHODS

We comprehensively examined 23 men with stable HFrEF (median age [interquartile range]: 63 [59-66] years; left ventricular ejection fraction: 28 [25-35]%; New York Heart Association class I/II/III: 17/43/39%). We analyzed clinical characteristics, iron status, hormones, strength and fatigability of forearm flexors and quadriceps (surface electromyography), and exercise capacity (6-minute walking test).

RESULTS

None of the patients had anemia whereas 8 were iron-deficient. Flexor carpi radialis fatigability correlated with lower reticulocyte hemoglobin content (CHR, p < 0.05), and there was a trend towards greater fatigability in patients with higher body mass index and lower serum ferritin (both p < 0.1). Flexor carpi ulnaris fatigability correlated with lower serum iron and CHR (both p < 0.05). Vastus medialis fatigability was related to lower free and bioavailable testosterone (FT and BT, respectively, both p < 0.05), and 6-minute walking test distance was shorter in patients with higher cortisol/FT and cortisol/BT ratio (both p < 0.05). Lower ferritin and transferrin saturation correlated with lower percentage of FT and BT. Men with HFrEF and iron deficiency had higher total testosterone, but lower percentage of FT and BT.

CONCLUSIONS

Iron deficiency correlates with lower bioactive testosterone in men with HFrEF. These two pathologies can both contribute to decreased skeletal muscle performance in such patients.

Intravenous iron therapy and circulating biomarkers of inflammation in men with heart failure with reduced ejection fraction

Background

Large randomized clinical trials have demonstrated that intravenous (IV) iron therapy in iron-deficient patients with heart failure with reduced ejection fraction (HFrEF) brings clinical benefits related to symptoms of the disease and exercise capacity. Mechanisms underlying beneficial effects of such repletion are still the subject of interest as this is not solely related to improved haematopoiesis (IV iron works also in non-anaemic subjects). In patients with chronic heart failure iron deficiency (ID) is linked with inflammatory processess but data regarding the impact of IV iron on inflammation is scarce.

Purposes

We evaluated whether IV iron therapy affects circulating biomarkers of pro-inflammatory state in men with HFrEF and concomitant ID.

Methods

This is the sub-analysis of the study to investigate the effects of IV ferric carboxymaltose (FCM) on the functioning of skeletal muscles in men with HFrEF. For the purposes of current research we analyzed data of 20 men with HFrEF (median age 68 (62, 75 – in brackets interquartile ranges, respectively) years, LVEF: 30 (25, 35) %, ischaemic HF aetiology: 85%, NYHA class I/II/III: 30%/50%/20%) and ID (definition according to ESC guidelines - ferritin &lt;100 ng/mL, or ferritin 100–299 ng/mL with transferrin saturation [TSAT] &lt;20%) who were randomized in a 1:1 ratio to receive either the 24-week therapy with IV FCM (dosing scheme as in the CONFIRM-HF trial) or saline (controls). The study was double-blinded. We used ELISA to evaluate different circulating pro-inflammatory biomarkers (high-sensitivity C-reactive protein [hs-CRP], tumor necrosis factor alpha [TNF-α], interleukin 6 [IL-6], interleukin 1 beta [IL-1β], interleukin 22 [IL-22]) at baseline and week 24.

Results

IV FCM therapy repleted iron stores in men with HFrEF as reflected by an increase in serum ferritin and TSAT, which was not seen in a control group. IV FCM therapy (as well as the saline administration) affected neither haemoglobin concentration nor parameters reflecting iron stores in red cells.

Baseline serum ferritin was not related to hs-CRP, TNF-α, IL-6, IL-1β, and IL-22 (all p&gt;0.23). Baseline TSAT was related to hs-CRP (r=−0.47, p=0.02) but not other inflammatory biomarkers.

Levels of hs-CRP, TNF-α, IL-6, IL-1β, and IL-22 at week 0 were similar in subjects who received IV iron and controls (all p&gt;0.22).

Change from week 0 to week 24 adjusted for baseline value (delta W24-W0 as the percentage of W0) regarding IL-22 was lower in an active treatment arm as compared with saline (p=0.049) and there was a trend towards lower delta TNF-α in FCM group compared to saline (p=0.067). These findings were not valid for other measured pro-inflammatory biomarkers.

Conclusions

In men with HFrEF and concomitant ID intravenous iron therapy with FCM affects biomarkers of pro-inflammatory state. Clinical relevance of this finding requires further translational research.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): This research was funded by the National Science Centre (Poland) grant allocated on the basis of the decision number DEC-2012/05/E/NZ5/00590

The role of cardiopulmonary exercise testing and echocardiography prior to elective endovascular aneurysm repair

INTRODUCTION

Cardiopulmonary exercise testing (CPET) and transthoracic echocardiography (TTE) are common preparative investigations prior to elective endovascular aneurysm repair (EVAR). Whether these investigations can predict survival following EVAR and contribute to shared decision making is unknown.

METHODS

Patients who underwent EVAR at a tertiary centre between June 2007 and December 2014 were identified from the National Vascular Registry. Variables obtained from preoperative investigations were assessed for their association with survival at three years. Regression analysis was used to determine variables that independently predicted survival at three years.

RESULTS

A total of 199 patients underwent EVAR during the study period. Of these, 120 had preoperative CPET and 123 had TTE. Lower forced expiratory ventilation (FEV₁), ratio of FEV₁ to forced vital capacity, work at peak oxygen consumption and higher ventilatory equivalent for carbon dioxide were associated with increased mortality. Variables obtained from TTE were not associated with survival at three years although there was a low incidence of left ventricular systolic dysfunction and significant valvular disease in this cohort.

CONCLUSIONS

CPET might be a useful adjunct to assist in shared decision making in patients undergoing elective EVAR and may influence anaesthetic technique. TTE does not appear to be able to discriminate between high and low risk individuals. However, a low rate of significant ventricular dysfunction and valvular disease in patients undergoing elective EVAR may account for these findings.

Multidimensional Approach to Frailty

The concept of frailty syndrome (FS) was first described in the scientific literature three decades ago. For a very long time, we understood it as a geriatric problem, recently becoming one of the dominant concepts in cardiology. It identifies symptoms of FS in one in 10 elderly people. It is estimated that in Europe, 17% of elderly people have FS. The changes in FS resemble and often overlap with changes associated with the physiological aging process of the body. Although there are numerous scientific reports confirming that FS is age correlated, it is not an unavoidable part of the aging process and does not apply only to the elderly. FS is a reversible clinical condition. To maximize benefits of frailty-reversing activities for patient with frailty, identification of its determinants appears to be fundamental. Many of the determinants of the FS have already been known: reduction in physical activity, malnutrition, sarcopenia, polypharmacy, depressive symptom, cognitive disorders, and lack of social support. This review shows that insight into FS determinants is the starting point for building both the comprehensive definition of FS and the adoption of the assessment method of FS, and then successful clinical management.

P1392 Association of iron deficiency with left ventricular longitudinal function abnormalities in patients with acute myocarditis

Background

Recent evidence suggests that iron depletion may be involved in the pathophysiology of acute myocarditis (MCD), however no data on the contribution of this mechanism to the MCD-associated cardiac performance abnormalities are available. The decrease in longitudinal deformation is an early manifestation of left ventricular (LV) dysfunction. Nonetheless, global longitudinal strain (GLS) is afterload-dependent, and the estimation of myocardial work correcting GLS for changes in systolic blood pressure may permit a more adequate assessment of LV contractility.

Aim

We sought to investigate the association between iron status and LV function in patients with MCD.

Methods

We prospectively included 30 patients (age 32 ± 8 years; 97% male) hospitalized for acute MCD in a tertiary cardiology center. MCD was diagnosed based on the following criteria: 1) new onset symptoms suggestive of myocarditis (exercise intolerance, dyspnea, palpitations or chest pain), 2) elevated high sensitivity cardiac troponin I (hscTnI), 3) exclusion of obstructive coronary artery disease, 4) confirmation of myocardial oedema based on T2 mapping in cardiac magnetic resonance. On admission, each participant underwent echocardiography with LV strain and myocardial work (global work index [GWI], global constructive work [GCW], global wasted work [GWW], global work efficiency [GWE]) analysis, and laboratory assessment including the iron status markers: ferritin and transferrin saturation (TSAT). Iron deficiency (ID) was defined as transferrin saturation (TSAT) &lt;20%; we did not use serum transferrin to categorize iron status because of the strong association of this marker with acute inflammation, which might affect the interpretation of its values.

Results

ID was found in 16 (53%) enrollees. Patients with reduced TSAT demonstrated lower GCW and GWI than their peers with normal TSAT (Table). No significant between-group differences were found for GLS, LV ejection fraction, early diastolic tissue velocity (e’) and E/e’ ratio. Both subsets did not significantly differ with respect to hemoglobin, creatinine, NT-proBNP, hscTnI and CRP. Both GWI and GCW significantly correlated with TSAT (r = 0.39, p = 0.03, and r = 0.37, p = 0.04, respectively). In multivariable analysis, after adjustment for patient age, body mass index, creatinine, hscTnI and CRP, TSAT was an independent predictor of GWI (beta = 0.40; p = 0.02) and GCW (beta = 0.38; p = 0.02).

Conclusion

In patients with MCD, ID defined as low TSAT is associated with a worse LV longitudinal performance as assessed by GCW and GWI, which might suggest a role of this pathophysiological pathway in the development of cardiac dysfunction. Myocardial work parameters seem to outperform GLS in diagnosing LV functional impairment in this clinical setting.

Abstract P1392 Figure.

Drug therapy in elderly heart failure patients

Although heart failure (HF) is considered as a cardiogeriatric syndrome, elderly and very elderly patients are under-represented in the vast majority of clinical trials investigating novel drugs and therapies in this population. The homoeostatic systems of elderly subjects are very fragile, and the management of HF accompanied by numerous comorbidities requires a holistic approach towards the patient, with special emphasis not only on psychosomatic problems but also on the individual (including social) needs of each particular patient, along with the support for the family and/or caregivers. In this article, we summarize current evidence regarding pharmacotherapy of elderly patients with HF and summarize the clinical problems occurring in this population.

Monitoring of iron status in patients with heart failure

The 2016 ESC/HFA heart failure (HF) guidelines emphasize the importance of identifying and treating iron deficiency (ID) in patients with HF. Iron deficiency can occur in half or more of HF sufferers, depending on age and the phase of the disease. Iron deficiency can be a cause of anaemia, but it is also common even without anaemia, meaning that ID is a separate entity, which should be screened for within the HF population. Although assessment of iron stores in bone marrow samples is the most accurate method to investigate iron status, it is not practical in most HF patients. Levels of circulating iron biomarkers are an easily available alternative; especially, ferritin and transferrin saturation (Tsat). In patients with HF serum ferritin level <100 µg/L (regardless of Tsat value) or between 100 and 299 µg/L with Tsat <20% are considered as recommended criteria for the diagnosis of ID, criteria which have been used in the clinical trials in HF that have led to a recommendation to treat ID with intravenous iron. We discuss the optimal measures of iron biomarkers in patients with HF in order to screen and monitor iron status and introduce some novel ways to assess iron status.

Iron Therapy

No abstract

P754Iron status indices (transferrin saturation, serum ferritin) in the course of acute myocarditis: relations with neurohormonal activation, cardiac dysfunction and clinical recovery

Introduction

Acute myocarditis (MCD) can progress to post-myocarditis cardiomyopathy. Immune response is the major pathophysiological trigger leading to MCD. Optimal iron status is essential for the functioning of immune cells, cardiomyocytes and cardiofibroblasts. Therefore, there are premises to consider iron metabolism as a significant modulator of complex pathophysiology of MCD.

Purpose

We aimed to assess iron status in the course of MCD and relate it with clinical and laboratory measures.

Methods

We prospectively enrolled consecutive patients hospitalized for acute MCD in 2 tertiary referral cardiology centers during 2015–2018 and followed them up for 30 weeks. MCD was diagnosed based on the following criteria: 1) new onset symptoms suggestive of myocarditis (effort intolerance, dyspnea, palpitations or chest pain), 2) elevated high sensitivity cardiac troponin I (hs-cTnI), 3) exclusion of obstructive coronary artery disease.

Results

Study group comprised 41 patients with confirmed MCD [age: 31 (26–34) years, men: 95%] and 15 healthy age- and gender-matched subjects [age: 30 (28–33) years, men: 87%]. All patients survived hospitalization and follow-up, no subject needed ventricular assist device.

Patients with MCD had lower LVEF (56±10% vs. 69±14%) and higher CRP [32 (14–8754) vs. 3 (3–3) mg/l], NT-proBNP [452 (240–877) vs. 33 (18–46) pg/ml], hs-cTnI [7.3 (3.3–12.8) vs. 0,01 (0.01–0.01) μg/l] than the control group (all p<0.001). Regarding iron status, MCD group presented higher serum ferritin [213 (121–386) vs. 135 (84–210) μg/l] and lower transferrin saturation (TSAT) [21±10 vs. 28±15%] (all p<0.05). In patients with MCD ferritin correlated with CRP (r=0.46, p<0.01), TSAT correlated neither with CRP nor with ferritin (all p>0.02).

Patients with MCD and NT-proBNP >1000 pg/ml had lower TSAT (16±8 vs. 23±9%; p<0.05) and LVEF (47±13 vs. 59±7%; p<0.001) than the remaining subjects. No difference in ferritin was observed (p>0.2). 46% of patients during acute phase of MCD had LVEF≤55% – these patients presented lower TSAT (17±8% vs. 24±10%) and higher NT-proBNP – [577 (436–1657) vs. 358 (167–499) pg/ml] (all p<0.05). After 30 weeks only in 13% patients LVEF≤55% persisted and related to lower baseline TSAT (9±1% vs. 21±9%) and higher CRP (147±113 vs. 52±40 mg/l) (all p<0.05). LVEF≤55% was not related to ferritin (both p>0.2).

After 6 weeks of follow-up patients with MCD already presented higher LVEF (61±8%; p<0.05) and haemoglobin [14.7 (14.0–15.7) g/dl], lower CRP [3 (3–3) mg/l], NT-proBNP [34 (25–67) pg/ml], hs-cTnI [0.01 (0.01–0.01)], ferritin [124 (78–168) μg/l] and higher TSAT (26±7%) (all p<0.01). There was no further change in these parameters within the next 24 weeks (all p>0.2).

Conclusions

Iron status is deranged in acute MCD. Serum ferritin is an indicator of inflammatory response, whereas TSAT relates to neurohormonal activation and cardiac dysfunction. Iron status normalizes within 6 weeks after acute phase of MCD.

Acknowledgement/Funding

This research was financially supported by the National Science Centre (Poland) grant number 2014/13/B/NZ5/03146.

P6353Iron depletion in human cardiomyocytes cultured with sera from myocarditis patients

Background

Cardiac myocytes, which are particularly sensitive to disordered iron homeostasis, are the main cells affected in the course of myocarditis. Iron is essential for the proper maintenance of energy metabolism but also plays key role in inflammation and ROS production. We hypothesize that iron homeostasis might be involved in the pathophysiology of myocarditis.

Purpose

The aim of the study was to assess differences in the expression of key genes and proteins involved in iron homeostasis, cardiac malfunctioning, and protection against ROS in human cardiomyocytes (HCMs) cultured in the indirect model of myocarditis.

Methods

HCMs were cultured for 48 hours with 10% of sera from patients with acute myocarditis (n=11) and after 6 weeks of recovery, and also with sera from healthy controls (n=7). We analyzed expression of light and heavy ferritin chains [FTL, FTH], transferrin receptor 1 [TfR1], galectin 3 [LGALs3], TGFβ signaling [TGFβ1, TGFβ2, TGFβ3], glutathione peroxidase [GPX] and superoxide dismutase [SOD1] at the mRNA level using RTqPCR and at the protein level using Western bloting. We compared obtained data with the clinical characteristics of patients.

Results

In HCMs exposed to sera from myocarditis patients, in comparison to those treated with sera from healthy controls, we found a significant increase in an expression of TfR1 both at mRNA and protein level (p<0,01). We also observed that elevated expression of TfR1 in cells correlated with serum levels of total iron (R=-0,52; p<0,05), CRP (R=0,67; p<0,05), and NT-proBNP (R=0,55; p<0,05), suggesting increased iron demand in HCMs and its possible relation to inflammation and hemodynamic dysfunction in patients.

Moreover, we observed elevated expression of FTH and FTL at the mRNA level (both p<0,01) and its strong correlation with expression of TfR1 as well as with increased levels of CRP in sera. It could be explained by the double role of ferritin in iron storage and in inflammation.

Interestingly, we noticed detrimental effects of myocarditis sera on HCMs reflected by augmented expression of galectin 3 (p<0,01) and disturbances in TGFβ genes, in comparison to those treated with sera from healthy controls. Augmented expression of galectin 3 was strongly related to disturbed iron homeostasis, manifesting itself by correlations with TfR1 (R=0,77; p<0,05), FTH (R=0,92; p<0,05) and FTL (R=0,76; p<0,05).

In addition, HCMs treated with sera from myocarditis patients showed an increase in expression of ROS protective genes such as SOD1 and GPX (both p<0,01), indicating higher oxidative stress in these cells.

We noticed that gene expression profile was similar in HCMs treated with sera collected after 6 weeks of clinical recovery, suggesting that the negative impact of sera was preserved.

Conclusions

Malfunctioning of cardiomyocytes in course of myocarditis might be related to disturbances in the iron homeostasis.

Acknowledgement/Funding

The present study was financially supported by the National Science Centre (Krakow, Poland; grant no. 2014/13/B/NZ5/03146)

Influence of psoas muscle area on mortality following elective abdominal aortic aneurysm repair

BACKGROUND

The effect of sarcopenia based on the total psoas muscle area (TPMA) on CT is inconclusive in patients undergoing abdominal aortic aneurysm (AAA) intervention. The aim of this prospective cohort study was to evaluate morphometric sarcopenia as a method of risk stratification in patients undergoing elective AAA intervention.

METHODS

TPMA was measured on preintervention CT images of patients undergoing elective endovascular aneurysm repair (EVAR) or open aneurysm repair. Mortality was assessed in relation to preintervention TPMA using Cox regression analysis, with calculation of hazard ratios at 30 days, 1 year and 4 years. Postintervention morbidity was evaluated in terms of postintervention care, duration of hospital stay and 30-day readmission. Changes in TPMA on surveillance EVAR imaging were also evaluated.

RESULTS

In total, 382 patient images acquired between March 2008 and December 2016 were analysed. There were no significant intraobserver and interobserver differences in measurements of TPMA. Preintervention TPMA failed to predict morbidity and mortality at all time points. The mean(s.d.) interval between preintervention and surveillance imaging was 361·3(111·2) days. A significant reduction in TPMA was observed in men on surveillance imaging after EVAR (mean reduction 0·63(1·43) cm2 per m2 ; P < 0·001). However, this was not associated with mortality (adjusted hazard ratio 1·00, 95 per cent c.i. 0·99 to 1·01; P = 0·935).

CONCLUSION

TPMA is not a suitable risk stratification tool for patients undergoing effective intervention for AAA.

Coronary subclavian steal syndrome-is there a need for routine assessment for subclavian artery stenosis following coronary bypass surgery?

Subclavian artery stenosis (SAS) resulting in coronary subclavian steal syndrome (CSSS) is a common but under recognized pathology following coronary artery bypass surgery (CABG). Patients with SAS may be asymptomatic due to the sub-clinical diversion of blood flow from the myocardium and retrograde blood flow during catheter angiography in the left internal mammary artery (LIMA) may be the first suggestion of CSSS. The management of SAS, causing CSSS, may rarely require acute assessment and intervention. However, full anatomical assessment of the stenosis morphology may be limited on fluoroscopy. Correction of SAS may be essential to achieve effective reperfusion therapy.

The theoretical and experimental vibrational studies of thiourea and silver nitrate (2:1) complex

The theoretical and experimental vibrational studies for poly thiourea silver nitrate (2:1) complex using DFT method are performed on the basis of experimental data. During the geometry optimization process one equilibrium structure was found. The Mulliken charges, harmonic vibrational frequencies, Infrared and Raman intensities were calculated on the basis of quantum chemical density functional calculations using firefly (PC GAMESS) Version 7.1G. The clear - cut assignments of observed bands are performed on the basis of potential energy distribution (PED) analysis. Highest Occupied Molecular Orbital (HOMO) and the Lowest Occupied Molecular Orbital (LUMO) are obtained and graphically illustrated with minimum energy. The energy difference between HOMO and LUMO is analyzed. The other molecular properties like molecular electrostatic potential, Mulliken charges and thermodynamic properties of the title compound have also been calculated.

Depleted iron stores are associated with inspiratory muscle weakness independently of skeletal muscle mass in men with systolic chronic heart failure

BACKGROUND

Skeletal and respiratory muscle dysfunction constitutes an important pathophysiological feature of heart failure (HF). We assessed the relationships between respiratory muscle function, skeletal muscle mass, and physical fitness in men with HF with reduced left ventricular ejection fraction (HFrEF), and investigated the hypothesis of whether iron deficiency (ID) contributes to respiratory muscle dysfunction in these patients.

METHODS

We examined 53 male outpatients with stable HFrEF without asthma or chronic obstructive pulmonary disease (age: 64 ± 10 years; New York Heart Association [NYHA] class I/II/III: 36/51/13%; ischaemic aetiology: 83%; all with left ventricular ejection fraction ≤40%) and 10 middle-aged healthy men (control group). We analysed respiratory muscle function (maximal inspiratory and expiratory pressure at the mouth [MIP and MEP, respectively]), appendicular lean mass/body mass index (ALM/BMI; ALM was measured using dual-energy X-ray absorptiometry), physical fitness (components of Functional Fitness Test for Older Adults), and iron status.

RESULTS

MIP, MEP, and ALM/BMI (but not MIP adjusted for ALM/BMI) were lower in men with HFrEF vs. healthy men. MIP, MEP, and MIP adjusted for ALM/BMI (but not ALM/BMI) were lower in men with HFrEF with vs. without ID. In a multivariable linear regression model lower serum ferritin (but not transferrin saturation) was associated with lower MIP independently of ALM/BMI, left ventricular ejection fraction, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and haemoglobin concentration. In multivariable linear regression models, lower MIP was associated with worse results in Functional Fitness Test when adjusted for ALM/BMI or relevant clinical variables (NYHA class, estimated glomerular filtration rate, NT-proBNP, and haemoglobin concentration).

CONCLUSIONS

In men with HFrEF, low ferritin reflecting depleted iron stores is associated with inspiratory muscle weakness independently of skeletal muscle mass. Inspiratory muscle dysfunction correlates with worse physical fitness independently of either skeletal muscle mass or disease severity.

SPRi-Based Biosensing Platforms for Detection of Specific DNA Sequences Using Thiolate and Dithiocarbamate Assemblies

The framework of presented study covers the development and examination of the analytical performance of surface plasmon resonance-based (SPR) DNA biosensors dedicated for a detection of model target oligonucleotide sequence. For this aim, various strategies of immobilization of DNA probes on gold transducers were tested. Besides the typical approaches: chemisorption of thiolated ssDNA (DNA-thiol) and physisorption of non-functionalized oligonucleotides, relatively new method based on chemisorption of dithiocarbamate-functionalized ssDNA (DNA-DTC) was applied for the first time for preparation of DNA-based SPR biosensor. The special emphasis was put on the correlation between the method of DNA immobilization and the composition of obtained receptor layer. The carried out studies focused on the examination of the capability of developed receptors layers to interact with both target DNA and DNA-functionalized AuNPs. It was found, that the detection limit of target DNA sequence (27 nb length) depends on the strategy of probe immobilization and backfilling method, and in the best case it amounted to 0.66 nM. Moreover, the application of ssDNA-functionalized gold nanoparticles (AuNPs) as plasmonic labels for secondary enhancement of SPR response is presented. The influence of spatial organization and surface density of a receptor layer on the ability to interact with DNA-functionalized AuNPs is discussed. Due to the best compatibility of receptors immobilized via DTC chemisorption: 1.47 ± 0.4 · 10¹² molecules · cm^-2 (with the calculated area occupied by single nanoparticle label of ~132.7 nm²), DNA chemisorption based on DTCs is pointed as especially promising for DNA biosensors utilizing indirect detection in competitive assays.

Cytotoxicity studies of selected cadmium-based quantum dots on 2D vs. 3D cell cultures

In our work, the cytotoxicity of selected, cadmium-based quantum dots with various surface architectures was studied on 3D spheroids.

Iron Therapy in Patients with Heart Failure and Iron Deficiency: Review of Iron Preparations for Practitioners

In patients with heart failure (HF), iron deficiency (ID) correlates with decreased exercise capacity and poor health-related quality of life, and predicts worse outcomes. Both absolute (depleted iron stores) and functional (where iron is unavailable for dedicated tissues) ID can be easily evaluated in patients with HF using standard laboratory tests (assessment of serum ferritin and transferrin saturation). Intravenous iron therapy in iron-deficient patients with HF and reduced ejection fraction has been shown to alleviate HF symptoms and improve exercise capacity and quality of life. In this paper, we provide information on how to diagnose ID in HF. Further we discuss pros and cons of different iron preparations and discuss the results of major trials implementing iron supplementation in HF patients, in order to provide practical guidance for clinicians on how to manage ID in patients with HF.

Iron Deficiency Treatment in Patients with Heart Failure

Iron deficiency (ID) is one of the major risk factors for disability and mortality worldwide, and it was identified as a common and ominous comorbidity in patients with heart failure (HF), both with and without anaemia. Based on two clinical trials (FAIR-HF and CONFIRM-HF) and other epidemiological evidence, ID has been recognized as an important therapeutic target in symptomatic patients with HF and LVEF ≤45%.Intravenous iron supplementation has been demonstrated to be safe and effective for iron repletion and related with an improvement in clinical status, exercise capacity, and quality of life. Ongoing trials are testing the hypothesis that such a therapy may also reduce the risk of HF hospitalizations and cardiovascular death.