Salivary biomarkers in cardiovascular disease: An insight into the current evidence

All-in-one microfluidic immunosensing device for rapid and end-to-end determination of salivary biomarkers of cardiovascular diseases

Routine screening for cardiovascular diseases (CVDs) through point-of-care assays for at-home or community-based testing of salivary biomarkers can significantly improve patient outcomes. However, its translatability has been hindered by a dearth of biosensing devices that streamline assay procedures for rapid biomarker quantitation. To address this challenge through end-to-end engineering, we developed an in-house, all-in-one microfluidic immunosensing device that integrates on-chip vibration-enhanced incubation, magnetic-assisted separation using immune magnetic bead probes, and colorimetric readout via absorbance measurements. This device enables probe preparation and one-pot immunoassay procedures on a reusable microfluidic chip. By engaging the vibrator with the reaction chamber, the vibration-enhanced incubation module significantly accelerates immune complex formation, drastically reducing the sample-to-answer timeline of approximately 1 h required for room temperature enzyme-linked immunosorbent assay (ELISA) to just under 15 min. We showcase the utility of the device with an on-demand assay for a biomarker panel comprising C-reactive protein (CRP), interleukin 6 (IL-6), and procalcitonin (PCT). The device achieved a linear detection range of 1.75-28 ng mL-1 for CRP and 1.56-100 ng mL-1 for IL-6 and PCT with an R2 > 0.98 for all three biomarkers. The limits of detection were 0.295, 0.400, and 0.947 ng mL-1, respectively. Results from real saliva samples were consistent with standard ELISA (R2 = 0.952). This fully integrated, modular immunosensing device opens up opportunities for household CVD screening and could be adapted for rapid, affordable multiplexed biosensing for other major chronic diseases at the point of care.

Assessing the feasibility of using salivary microRNAs as biomarkers to distinguish between chronic stress and childhood trauma in African American young women in an exploratory pilot study

Introduction

The current study assessed the impact of self-reported stress measures on microRNA (miRNA) profiles in saliva exosomes. Saliva is one of the most accessible and non-invasive bodily fluids and exosomal miRNAs in saliva could be useful in (1) measuring stress states and (2) distinguishing between individuals suffering from high levels of chronic stress vs. adverse childhood experiences (ACEs). miRNAs are small, noncoding RNAs that act as gene regulators. Several studies have shown differential expressions of certain miRNA in neurological diseases and in stress, post-traumatic stress syndrome (PTSD) and anxiety. Detailed analyses of miRNA expressions and profiling of miRNAs among populations with various exposures to traumatic and life stressors have not been carried out. The goal of our study was to discover miRNAs associated with high chronic stress or childhood trauma.

Method

This study sought to explore miRNA expression in African American young women from a small, southern Historically Black College and University (HBCU). Twelve participants completed the social readjustment rating scale (SRRS), ACEs scale, and saliva collection and were divided into three groups based on ACE and chronic stress score: Low Chronic Stress (LCS; n = 4); High Chronic Stress (HCS; n = 4); High Chronic Stress + High ACEs (HCS+HA; n=4). A custom-made miRNA Taqman-Array tested for fold change in four miRNAs (i.e., miR-19b, miR-187, miR-34a and miR-135-3p).

Results

There was a significant downregulation of miR-19b (χ 2(2, N=12) = 7.42, p < 0.01, η²= 0.915), miR-187 (χ 2 (2, N = 12) = 7.36, p < 0.05, η²= 0.598), and miR-34a (χ 2(2, N = 12) = 7.42, p < 0.05, η²= 0.60). in both the HCS and the HCS+HA groups vs. LCS. Interestingly, miR-135-3p (χ 2(2, N = 12) = 8.00, p < 0.05, η²= 0.67. was upregulated in the HCS group vs. LCS and HCS+LA. Expression for miR-135-3p was not significantly different between LCS + HCS+HA.

Conclusion

Our analyses shows that miRNA extracted from salivary exosomes can be a reliable biomarker for stress and miR-135a-3p appears to be the most upregulated between LCS and HCS individuals and a potential candidate to corroborate self-reports on self-assessments and predict negative health outcomes. Given that HCS+HA did not show an upregulation of miR-135-3p but had similar expression in the other three miRs compared to HCS group may indicate an adaptive stress response following early life adversity. Further, downregulation in miR-135-3p in individuals with high levels of chronic stress could point to unknown childhood trauma exposure (e.g. closed adoptions, dissociative amnesia, abuse). A major limitation in this study is the small sample size and future directions include determining the predictive validity of these miRNAs in predicting onset of physical and mental health outcomes for early interventions in larger studies.

Distinctive blood and salivary proteomics signatures in Qatari individuals at high risk for cardiovascular disease

Cardiovascular disease (CVD) remains a leading cause of global morbidity and mortality. Timely diagnosis is important in reducing both short and long-term health complications. Saliva has emerged as a potential source for biomarker discovery, offering a non-invasive tool for early detection of individuals at elevated risk for CVD, yet large-scale extensive proteomic analysis using saliva for a comprehensive biomarker discovery remains limited. In an effort to develop a diagnostic tool using saliva samples, our study aims to assess the salivary and plasma proteomes in subjects with high risk of developing CVD using a large-scale proteomic approach. Leveraging on the SOMAscan platform, we analyzed 1,317 proteins in saliva and plasma collected from subjects at a high risk of CVD (HR-CVD) and compared the profiles to subjects with low risk of CVD (LR-CVD). Our analysis revealed significant differences in the plasma and salivary proteins between the two groups. Pathway enrichment analysis of the differentially detected proteins revealed that the immune system activation and extracellular matrix remodeling are the most enriched pathways in the CVD-HR group. Comparing proteomic signatures between plasma and saliva, we found approximately 42 and 17 differentially expressed proteins associated with CVD-HR uniquely expressed in plasma and saliva respectively. Additionally, we identified eight common CVD-risk biomarkers shared between both plasma and saliva, demonstrating promising diagnostic tools for identifying individuals at high risk of developing CVD. In conclusion, saliva proteomics holds a significant promise to identify subjects with a high risk to develop CVD. Further studies are needed to validate our findings.

Salivary Nitrate Level and Lipid Profile in Patients with Hypertension: A Cross-Sectional Study in a Saudi Sub-Population

Background: The use of salivary biomarkers offers a non-invasive approach to understanding the metabolic and inflammatory status of hypertensive patients. This study aimed to quantify the salivary nitric oxide (NO), total cholesterol, triglycerides, high-density lipoproteins (HDL), and low-density lipoproteins (LDL) levels in hypertensive individuals and healthy controls in a sub-population in Saudi Arabia. Methods: This cross-sectional study comprised 40 hypertensive patients (test group, 40-50 years old) and 40 age-matched healthy controls who visited the dental hospital in the College of Dentistry, King Khalid University, for dental treatment. Nitric oxide, total cholesterol, triglycerides, HDL, and LDL levels in saliva were assessed. An independent sample t-test was used to compare the results between the hypertensive and control groups. Results: The mean triglyceride and cholesterol levels in the test group were significantly higher (p < 0.05) than those in the control group. Alternatively, the NO level in the test group was significantly (p = 0.014) lower than that in the controls. The triglyceride level was significantly correlated with age in the test group (p = 0.04). Conclusions: This study demonstrated significant differences in the nitrate levels and lipid profiles between hypertensive patients and healthy individuals in a sub-population in Saudi Arabia. The findings indicate that saliva can be used as a non-invasive diagnostic tool for assessing nitrate levels and the lipid profile. However, additional studies with larger sample sizes and more precise testing parameters are required to validate the findings.

Exercise and brain health in patients with coronary artery disease: study protocol for the HEART-BRAIN randomized controlled trial

Introduction

Patients with coronary artery disease (CAD) have a higher risk of developing cognitive impairment and mental health disorders compared to the general population. Physical exercise might improve their brain health. The overall goal of the HEART-BRAIN randomized controlled trial (RCT) is to investigate the effects of different types of exercise on brain health outcomes in patients with CAD, and the underlying mechanisms.

Methods

This three-arm, single-blinded RCT will include 90 patients with CAD (50-75 years). Participants will be randomized into: (1) control group-usual care (n = 30), (2) aerobic high-intensity interval training (HIIT) (n = 30), or (3) HIIT combined with resistance exercise training (n = 30). The 12-week intervention includes 3 supervised sessions (45-min each) per week for the exercise groups. Outcomes will be assessed at baseline and post-intervention. The primary outcome is to determine changes in cerebral blood flow assessed by magnetic resonance imaging. Secondary outcomes include changes in brain vascularization, cognitive measures (i.e., general cognition, executive function and episodic memory), and cardiorespiratory fitness. Additional health-related outcomes, and several potential mediators and moderators will be investigated (i.e., brain structure and function, cardiovascular and brain-based biomarkers, hemodynamics, physical function, body composition, mental health, and lifestyle behavior).

Conclusion

The HEART-BRAIN RCT will provide novel insights on how exercise can impact brain health in patients with CAD and the potential mechanisms explaining the heart-brain connection, such as changes in cerebral blood flow. The results may have important clinical implications by increasing the evidence on the effectiveness of exercise-based strategies to delay cognitive decline in this high-risk population.

Clinical trial registration

ClinicalTrials.gov, identifier [NCT06214624].

Identification of diagnostic biomarkers used in the diagnosis of cardiovascular diseases and diabetes mellitus: A systematic review of quantitative studies

AIMS

To perform a systematic review of studies that sought to identify diagnostic biomarkers for the diagnosis of cardiovascular diseases (CVDs) and diabetes mellitus (DM), which could be used in low- and middle-income countries (LMICs) where there is a lack of diagnostic equipment, treatments and training.

MATERIALS AND METHODS

Papers were sourced from six databases: the British Nursing Index, Google Scholar, PubMed, Sage, Science Direct and Scopus. Articles published between January 2002 and January 2023 were systematically reviewed by three reviewers and appropriate search terms and inclusion/exclusion criteria were applied.

RESULTS

A total of 18 studies were yielded, as well as 234 diagnostic biomarkers (74 for CVD and 160 for DM). Primary biomarkers for the diagnosis of CVDs included growth differentiation factor 15 and neurogenic locus notch homologue protein 1 (Notch1). For the diagnosis of DM, alpha-2-macroglobulin, C-peptides, isoleucine, glucose, tyrosine, linoleic acid and valine were frequently reported across the included studies. Advanced analytical techniques, such as liquid chromatography mass spectrometry, enzyme-linked immunosorbent assays and vibrational spectroscopy, were also repeatedly reported in the included studies and were utilized in combination with traditional and alternative matrices such as fingernails, hair and saliva.

CONCLUSIONS

While advanced analytical techniques are expensive, laboratories in LMICs should carry out a cost-benefit analysis of their use. Alternatively, laboratories may want to explore emerging techniques such as infrared, Fourier transform-infrared and near-infrared spectroscopy, which allow sensitive noninvasive analysis.

Label-Free Classification of L-Histidine Vs Artificial Human Sweat Using Laser Scribed Electrodes and a Multi-Layer Perceptron Neural Network

A challenge in wearable technology lies in the realtime monitoring of molecular biomarkers associated with human health. Electrochemical sensors are one of the most useful tools for this purpose and are commonly used in health monitoring devices. Electrochemical biosensing is particularly convenient when used in user-friendly, low-cost devices for testing noninvasive body fluids such as sweat and saliva. However, achieving high selectivity and specificity in measurements depends on the complexity of the biomarker and the stability of the biomarker capture molecule. In this study, laser-scribed electrodes (LSEs) were manufactured using a CO2 laser cutter on Polyimide for the label-free classification of sweat components. Cyclic voltammetry experiments were performed on artificial human sweat and the sweat component L-Histidine. The resulting voltammogram data served as input to train a Multi-Layer Perceptron Neural Network (MLP-NN) algorithm capable of classifying L-Histidine and artificial sweat.

Oral Fluid Biomarkers for Peri-Implantitis: A Scoping Review

Peri-implantitis, a prevalent complication in dental implant therapy, poses a significant threat to long-term implant success. The identification of reliable biomarkers for the early detection and monitoring of peri-implantitis is crucial for timely intervention and improved treatment outcomes. Salivary and peri-implant sulcular fluid (PISF) biomarkers have become promising diagnostic tools in the field of implant dentistry. This scoping review aims to explore current studies in the literature on salivary and PISF biomarkers for peri-implantitis. A systematic search was conducted on 2 databases (PubMed and Scopus) to identify relevant studies published up to January 2023. A total of 86 articles were included, which underwent data extraction and analysis. Several biomarkers have been investigated in salivary and PISF samples for association with peri-implantitis. Investigations included a wide range of biomarkers, including inflammatory markers, matrix metalloproteinases and bone loss markers. The findings suggested that certain salivary and PISF biomarkers demonstrated potential in distinguishing healthy peri-implant conditions from peri-implantitis. Elevated levels of proinflammatory cytokines, such as interleukin-1β (IL-1β) and interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), and matrix metalloproteinases, have been consistently associated with peri-implantitis. Additionally, alterations in bone loss markers have shown potential as indicators of disease progression and treatment response. In conclusion, this scoping review provides an overview of current knowledge on salivary and PISF biomarkers for peri-implantitis. The identified biomarkers are promising as noninvasive diagnostic tools for early detection, monitoring, and personalised management of peri-implantitis. Future studies should focus on establishing standardised protocols and conducting well-designed clinical trials to validate the diagnostic accuracy and clinical relevance of these biomarkers.

The Potential Role of Salivary NT-proBNP in Heart Failure

BACKGROUND

Serum natriuretic peptides (NPs) have an established role in heart failure (HF) diagnosis. Saliva NT-proBNP that may be easily acquired has been studied little.

METHODS

Ninety-nine subjects were enrolled; thirty-six obese or hypertensive with dyspnoea but no echocardiographic HF findings or raised NPs served as controls, thirteen chronic HF (CHF) patients and fifty patients with acute decompensated HF (ADHF) requiring hospital admission. Electrocardiogram, echocardiogram, 6 min walking distance (6MWD), blood and saliva samples, were acquired in all participants.

RESULTS

Serum NT-proBNP ranged from 60-9000 pg/mL and saliva NT-proBNP from 0.64-93.32 pg/mL. Serum NT-proBNP was significantly higher in ADHF compared to CHF (p = 0.007) and in CHF compared to controls (p < 0.05). There was no significant difference in saliva values between ADHF and CHF, or between CHF and controls. Saliva and serum levels were positively associated only in ADHF patients (R = 0.352, p = 0.012). Serum NT-proBNP was positively associated with NYHA class (R = 0.506, p < 0.001) and inversely with 6MWD (R = -0.401, p = 0.004) in ADHF. Saliva NT-proBNP only correlated with age in ADHF patients.

CONCLUSIONS

In the current study, saliva NT-proBNP correlated with serum values in ADHF patients, but could not discriminate between HF and other causes of dyspnoea. Further research is needed to explore the value of saliva NT-proBNP.

Development of saliva-based cardiac troponin I point-of-care test using alpha-amylase depletion: a feasibility study

INTRODUCTION

Cardiac troponin (cTn) is the biomarker of choice for detection of myocardial injury. There is a great need for simple point-of-care (POC) troponin testing among patients with chest pain, mainly in the prehospital setting. The purpose of this study was to evaluate the presence of cardiac troponin I (cTnI) in saliva of patients with myocardial injury using alpha-amylase depletion technique.

METHODS

Saliva samples were collected from 40 patients with myocardial injury who were tested positive for conventional high-sensitivity cardiac troponin T (cTnT) blood tests, and from 66 healthy volunteers. Saliva samples were treated for the removal of salivary alpha-amylase. Treated and untreated samples were tested with blood cTnI Rapid Diagnostic Test. Salivary cTnI levels were compared to blood cTnT levels.

RESULTS

Thirty-six of 40 patients with positive blood cTnT had positive salivary samples for cTnI following alpha-amylase depletion treatment (90.00% sensitivity). Moreover, three of the four negative saliva samples were obtained from patients with relatively low blood cTnT levels of 100 ng/L or less (96.88% sensitivity for 100 ng/L and above). The negative predictive value was 93.65% and rose up to 98.33% considering the 100 ng/L cutoff. Positive predictive values were 83.72% and 81.58%, respectively. Among 66 healthy volunteers and 7 samples yielded positive results (89.39% specificity).

CONCLUSION

In this preliminary work, the presence of cTnI in saliva was demonstrated for the first time to be feasibly identified by a POC oriented assay. The specific salivary alpha-amylase depletion technique was shown to be crucial for the suggested assay.

Modern View on the Role of Sex-Specific Levels of High-Sensitive Cardiospecific Troponins T and I in the Diagnosis of Myocardial Infarction

It is well known that the molecules of cardiospecific troponins T and I are localized in the troponin-tropomyosin complex of the cytoplasm of cardiac myocytes and, due to the specific localization, these cardiospecific troponins are widely used as diagnostic biomarkers of myocardial infarction. Cardiospecific troponins are released from the cytoplasm of cardiac myocytes as a result of irreversible cell damage (for example, ischemic necrosis of cardiomyocytes in myocardial infarction or apoptosis of cardiac myocytes in cardiomyopathies and heart failure) or reversible damage (for example, intense physical exertion, hypertension, the influence of stress factors, etc.). Current immunochemical methods for determining cardiospecific troponins T and I have extremely high sensitivity to subclinical (minor) damage to myocardial cells and, thanks to modern high-sensitive methods, it is possible to detect damage to cardiac myocytes in the early (subclinical) stages of a number of cardiovascular pathologies, including myocardial infarction. So, recently, leading cardiological communities (the European Society of Cardiology, the American Heart Association, the American College of Cardiology, etc.) have approved algorithms for early diagnosis of myocardial infarction based on the assessment of serum levels of cardiospecific troponins in the first 1 - 3 h after the onset of pain syndrome. An important factor that may affect early diagnostic algorithms of myocardial infarction are sex-specific features of serum levels of cardiospecific troponins T and I. This manuscript presents a modern view on the role of sex-specific serum levels of cardiospecific troponins T and I in the diagnosis of myocardial infarction and the mechanisms of formation of sex-specific serum levels of troponins.

Updates and Original Case Studies Focused on the NMR-Linked Metabolomics Analysis of Human Oral Fluids Part III: Implementations for the Diagnosis of Non-Cancerous Disorders, Both Oral and Systemic

This communication represents Part III of our series of reports based on the applications of human saliva as a useful and conveniently collectable medium for the discovery, identification and monitoring of biomarkers, which are of some merit for the diagnosis of human diseases. Such biomarkers, or others reflecting the dysfunction of specific disease-associated metabolic pathways, may also be employed for the prognostic pathological tracking of these diseases. Part I of this series set the experimental and logistical groundwork for this report, and the preceding paper, Part II, featured the applications of newly developed metabolomics technologies to the diagnosis and severity grading of human cancer conditions, both oral and systemic. Clearly, there are many benefits, both scientific and economic, associated with the donation of human saliva samples (usually as whole mouth saliva) from humans consenting to and participating in investigations focused on the discovery of biomolecular markers of diseases. These include usually non-invasive collection protocols, relatively low cost when compared against blood sample collection, and no requirement for clinical supervision during collection episodes. This paper is centred on the employment and value of 'state-of-the-art' metabolomics technologies to the diagnosis and prognosis of a wide range of non-cancerous human diseases. Firstly, these include common oral diseases such as periodontal diseases (from type 1 (gingivitis) to type 4 (advanced periodontitis)), and dental caries. Secondly, a wide range of extra-oral (systemic) conditions are covered, most notably diabetes types 1 and 2, cardiovascular and neurological diseases, and Sjögren's syndrome, along with a series of viral infections, e.g., pharyngitis, influenza, HIV and COVID-19. Since the authors' major research interests lie in the area of the principles and applications of NMR-linked metabolomics techniques, many, but not all, of the studies reviewed were conducted using these technologies, with special attention being given to recommended protocols for their operation and management, for example, satisfactory experimental model designs; sample collection and laboratory processing techniques; the selection of sample-specific NMR pulse sequences for saliva analysis; and strategies available for the confirmation of resonance assignments for both endogenous and exogenous molecules in this biofluid. This article also features an original case study, which is focussed on the use of NMR-based salivary metabolomics techniques to provide some key biomarkers for the diagnosis of pharyngitis, and an example of how to 'police' such studies and to recognise participants who perceive that they actually have this disorder but do not from their metabolic profiles and multivariate analysis pattern-based clusterings. The biochemical and clinical significance of these multidimensional metabolomics investigations are discussed in detail.

Associations of siesta and total sleep duration with hypertension or cardiovascular diseases in middle-aged and older adults

BACKGROUND

Whether the ratio of siesta duration in the total sleep duration was associated with the occurrence of hypertension or cardiovascular diseases (CVDs) was unclear.

HYPOTHESIS

To explore the associations of siesta, and siesta ratio with hypertension or CVDs in middle-aged and older adults.

METHODS

This cohort study collected the data of 9247 middle-aged and older adults. The associations of siesta, and siesta ratio with hypertension were analyzed in 7619 participants while the associations of siesta, and siesta ratio with CVDs were analyzed in 8685 participants via univariate and multivariate logistic regression analysis.

RESULTS

Total sleep duration < 6 h (odd ratio [OR] = 1.168, 95% confidence interval [CI]: 1.023-1.335) and siesta ratios ≥ 0.4 (OR = 1.712, 95% CI: 1.129-2.594) were associated with increased risk of hypertension in middle-aged and older adults. Siesta ratio ≥ 0.4 was linked with higher risk of hypertension in males aged ≥ 60 years and total sleep duration < 6 h was correlated with elevated risk of hypertension in males < 60 years. The risk of CVDs was elevated in people with siesta duration < 0.5 h (OR = 2.053, 95% CI: 1.323-3.185). In females ≥60 years, the sleep duration at night < 6 h was associated with increased risk of CVDs. In females < 60 years, increased risk was observed in those with siesta duration < 0.5 h and sleep duration at night < 6 h.

CONCLUSION

Short sleep duration or high siesta ratio were associated with higher risk of hypertension. Short siesta duration, sleep duration at night or total sleep duration were correlated with an elevated risk of CVDs.

Detection of Autoantibodies in Saliva as New Avenue for the Diagnosis and Management of Autoimmune Patients

(1) Background: Autoimmune diseases are characterized by autoantibodies directed to a large number of antigenic targets and are measured using serum as sample matrix. Although serum is a very common specimen type, it comes with certain drawbacks. Most importantly, it depends on venous puncture and requires medical personnel for sampling. This is of particular importance in light of the limited healthcare access of patients with autoimmune diseases during the COVID-19 pandemic. Consequently, alternative sample matrices are being explored for the measurement of autoantibodies. Our study aimed to establish the feasibility of measuring autoantibodies in saliva samples using a novel and highly sensitive method for the detection of autoantibodies. (2) Methods: A total of 48 serum/saliva pairs were collected and tested using a novel particle-based multi-analyte technology (PMAT) system for the presence of a wide range of autoantibodies. (3) Results: A high level of correlation was observed between the results obtained with serum and saliva (Spearman’s rho = 0.725). Study participants clearly preferred saliva over serum sampling as part of the usability assessment. (4) Conclusions: Saliva represents a promising alternative sample matrix for the detection of autoantibodies. The usability study showed a clear preference of saliva over serum as a sample matrix.

End-to-end design of wearable sensors

Wearable devices provide an alternative pathway to clinical diagnostics by exploiting various physical, chemical and biological sensors to mine physiological (biophysical and/or biochemical) information in real time (preferably, continuously) and in a non-invasive or minimally invasive manner. These sensors can be worn in the form of glasses, jewellery, face masks, wristwatches, fitness bands, tattoo-like devices, bandages or other patches, and textiles. Wearables such as smartwatches have already proved their capability for the early detection and monitoring of the progression and treatment of various diseases, such as COVID-19 and Parkinson disease, through biophysical signals. Next-generation wearable sensors that enable the multimodal and/or multiplexed measurement of physical parameters and biochemical markers in real time and continuously could be a transformative technology for diagnostics, allowing for high-resolution and time-resolved historical recording of the health status of an individual. In this Review, we examine the building blocks of such wearable sensors, including the substrate materials, sensing mechanisms, power modules and decision-making units, by reflecting on the recent developments in the materials, engineering and data science of these components. Finally, we synthesize current trends in the field to provide predictions for the future trajectory of wearable sensors.

Metabolic Pathway of Cardiospecific Troponins: From Fundamental Aspects to Diagnostic Role (Comprehensive Review)

Many molecules of the human body perform key regulatory functions and are widely used as targets for the development of therapeutic drugs or as specific diagnostic markers. These molecules undergo a significant metabolic pathway, during which they are influenced by a number of factors (biological characteristics, hormones, enzymes, etc.) that can affect molecular metabolism and, as a consequence, the serum concentration or activity of these molecules. Among the most important molecules in the field of cardiology are the molecules of cardiospecific troponins (Tns), which regulate the processes of myocardial contraction/relaxation and are used as markers for the early diagnosis of ischemic necrosis of cardiomyocytes (CMC) in myocardial infarction (MI). The diagnostic value and diagnostic capabilities of cardiospecific Tns have changed significantly after the advent of new (highly sensitive (HS)) detection methods. Thus, early diagnostic algorithms of MI were approved for clinical practice, thanks to which the possibility of rapid diagnosis and determination of optimal tactics for managing patients with MI was opened. Relatively recently, promising directions have also been opened for the use of cardiospecific Tns as prognostic markers both at the early stages of the development of cardiovascular diseases (CVD) (arterial hypertension (AH), heart failure (HF), coronary heart disease (CHD), etc.), and in non-ischemic extra-cardiac pathologies that can negatively affect CMC (for example, sepsis, chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), etc.). Recent studies have also shown that cardiospecific Tns are present not only in blood serum, but also in other biological fluids (urine, oral fluid, pericardial fluid, amniotic fluid). Thus, cardiospecific Tns have additional diagnostic capabilities. However, the fundamental aspects of the metabolic pathway of cardiospecific Tns are definitively unknown, in particular, specific mechanisms of release of Tns from CMC in non-ischemic extra-cardiac pathologies, mechanisms of circulation and elimination of Tns from the human body, mechanisms of transport of Tns to other biological fluids and factors that may affect these processes have not been established. In this comprehensive manuscript, all stages of the metabolic pathway are consistently and in detail considered, starting from release from CMC and ending with excretion (removal) from the human body. In addition, the possible diagnostic role of individual stages and mechanisms, influencing factors is analyzed and directions for further research in this area are noted.

The Importance of Cardiac Troponin Metabolism in the Laboratory Diagnosis of Myocardial Infarction (Comprehensive Review)

The study of the metabolism of endogenous molecules is not only of great fundamental significance but also of high practical importance, since many molecules serve as drug targets and/or biomarkers for laboratory diagnostics of diseases. Thus, cardiac troponin molecules have long been used as the main biomarkers for confirmation of diagnosis of myocardial infarction, and with the introduction of high-sensitivity test methods, many of our ideas about metabolism of these cardiac markers have changed significantly. In clinical practice, there are opening new promising diagnostic capabilities of cardiac troponins, the understanding and justification of which are closely connected with the fundamental principles of the metabolism of these molecules. Our current knowledge about the metabolism of cardiac troponins is insufficient and extremely disconnected from various literary sources. Thus, many researchers do not sufficiently understand the potential importance of cardiac troponin metabolism in the laboratory diagnosis of myocardial infarction. The purpose of this comprehensive review is to systematize information about the metabolism of cardiac troponins and during the discussion to focus on the potential impact of cTns metabolism on the laboratory diagnosis of myocardial infarction. The format of this comprehensive review includes a sequential consideration and analysis of the stages of the metabolic pathway, starting from possible release mechanisms and ending with elimination mechanisms. This will allow doctors and researchers to understand the significant importance of cTns metabolism and its impact on the laboratory diagnosis of myocardial infarction.

Biology of Cardiac Troponins: Emphasis on Metabolism

Understanding of the biology of endo- and exogenous molecules, in particular their metabolism, is not only of great theoretical importance, but also of high practical significance, since many molecules serve as drug targets or markers for the laboratory diagnostics of many human diseases. Thus, cardiac troponin (cTns) molecules have long been used as key markers for the confirmation of diagnosis of myocardial infarction (MI), and with the introduction of contemporary (high sensitivity) test methods, many of our concepts related to the biology of these cardiac markers have changed significantly. In current clinical practice, there are opening new promising diagnostic capabilities of cTns, the understanding and justification of which is closely connected with the theoretical principles of the metabolism of these molecules. However, today, the biology and metabolism of cTns have not been properly investigated; in particular, we do not know the precise mechanisms of release of these molecules from the myocardial cells (MCs) of healthy people and the mechanisms of circulation, and the elimination of cTns from the bloodstream. The main purpose of this manuscript is to systematize information about the biology of cTns, with an emphasis on the metabolism of cTns. The format of this paper, starting with the release of cTns in the blood and concluding with the metabolism/filtration of troponins, provides a comprehensive yet logically easy way for the readers to approach our current knowledge in the framework of understanding the basic mechanisms by which cTns are produced and processed. Conclusions. Based on the analysis of the current literature, the important role of biology and all stages of metabolism (release, circulation, removal) of cTns in laboratory diagnostics should be noted. It is necessary to continue studying the biology and metabolism of cTns, because this will improve the differential diagnosis of MI and i a new application of cTns immunoassays in current clinical practice.

Oxidative Stress in the Pathogenesis of Aorta Diseases as a Source of Potential Biomarkers and Therapeutic Targets, with a Particular Focus on Ascending Aorta Aneurysms

Aorta diseases, such as ascending aorta aneurysm (AsAA), are complex pathologies, currently defined as inflammatory diseases with a strong genetic susceptibility. They are difficult to manage, being insidious and silent pathologies whose diagnosis is based only on imaging data. No diagnostic and prognostic biomarkers or markers of outcome have been known until now. Thus, their identification is imperative. Certainly, a deep understanding of the mechanisms and pathways involved in their pathogenesis might help in such research. Recently, the key role of oxidative stress (OS) on the pathophysiology of aorta disease has emerged. Here, we describe and discuss these aspects by revealing some OS pathways as potential biomarkers, their underlying limitations, and potential solutions and approaches, as well as some potential treatments.