Membrane Cholesterol and the Formation of Cholesterol Domains in the Pathogenesis of Cardiovascular Disease

At least three types of cholesterol-rich membrane domains have been described in biological membranes including cholesterol rafts, membrane caveolae and crystalline cholesterol domains,. While clear biological functions have been ascribed to both rafts and caveolae, little attention has been directed to the biological consequences of cholesterol enrichment of cell membranes and the formation of cholesterol domains. Elevated blood cholesterol levels have been shown to result in the enrichment of the cell plasma membrane with cholesterol in arterial smooth muscle cells (SMC), endothelial cells (EC) and cardiac myocytes. In the early period of cholesterol feeding (within days), the cell membrane enriches with cholesterol and membrane viscosity and membrane bilayer width increase. This latter effect severely alters membrane protein function, and recent data indicates that this induces the modulation of vascular cells (SMC and EC) to the atherosclerotic phenotype. In cardiac myocytes these membrane modifications appear to induce alterations in gene expression patterns that lead to the development of a heart failure phenotype. In addition, as the cholesterol content increases, phase separation of cholesterol occurs resulting in the formation of immiscible cholesterol domains within the membrane. These domains likely initiate nucleation of cholesterol crystals which would explain the origin of “cholesterol clefts” in atherosclerotic lesions. Taken together, these membrane alterations secondary to cholesterol enrichment constitute a “membrane lesion” which contribute to the very early pathogenic events underlying major human diseases including coronary artery disease, stroke and heart failure.     

Label‐Free Detection of Transferrin Receptor by a Designed Ligand‐Protein Sensor

Advanced detection of biomarkers in biofluids plays an important role in disease diagnosis and prognosis. Current techniques with pre‐labelling suffer from high cost and complicated operation, etc. Herein, we designed a label‐free electrochemical biosensor for rapid detection of transferrin receptor with desirable linear range, sensitivity, specificity, reproducibility, and stability for practical applications.     

Rational molecular targeting of the inter-subunit interaction between human cardiac troponin hcTnC and hcTnI using switch peptide-competitive biogenic medicines

The human cardiac troponin (hcTn) has been implicated in diverse cardiovascular diseases (CDs). The protein function is regulated by the inter-subunit interaction between the N-terminal domain of hcTnC and the C-terminal switch peptide of hcTnI; disruption of the interaction has been recognized as a potential therapeutic strategy for CDs. Here, we report use of biogenic medicines as small-molecule competitors to directly disrupt the protein–protein interaction by competitively targeting the core binding site (CBS) of hcTnC NTD domain. A multistep virtual screening protocol is performed against a biogenic compound library to identify competitor candidates and competition assay is employed to verify the screening results. Consequently, two compounds Collismycin and Compound e are identified as strong competitors (CC₅₀ < 10 μM) with hcTnI for hcTnC CBS site, while other tested compounds are found to have moderate (CC₅₀ = 10–100 μM), low (CC₅₀ > 100 μM) or no (CC₅₀ = N.D.) potency. The competitor ligands are anchored at the core groove of hcTnC CBS site through aromatic and hydrophobic interactions, while few peripheral hydrogen bonds are formed to further confer specificity for domain–compound recognition. These molecular-level findings would benefit from further in vitro and in vivo studies at cellular and animal levels, which can help to practice the ultimate therapeutic purpose.     

Injectable Polyzwitterionic Lubricant for Complete Prevention of Cardiac Adhesion

After cardiac surgery, tissue damage to the heart may cause adhesion between heart and its surrounding tissues. Post-operative cardiac adhesion may lead to limited normal cardiac function, decreased quality of cardiac surgery, and increased risk of major bleeding during reoperation. Therefore, it is necessary to develop an effective anti-adhesion therapy to overcome cardiac adhesion. An injectable polyzwitterionic lubricant is developed to prevent adhesion between the heart and surrounding tissues and to maintain normal pumping function of the heart. This lubricant is evaluated in a rat heart adhesion model. Poly (2-methacryloyloxyethyl phosphorylcholine) (i.e., PMPC) polymers are successfully prepared via free radical polymerization of monomer MPC, and the optimal lubricating performance, biocompatibility both in vitro and in vivo is demonstrated. Besides, a rat heart adhesion model is conducted to evaluate the bio-functionality of lubricated PMPC. The results prove that PMPC is a promising lubricant for complete adhesion-prevention. The injectable polyzwitterionic lubricant shows excellent lubricating properties and biocompatibility and can effectively prevent cardiac adhesion.     

Flexible Conductive Decellularized Fish Skin Matrix as a Functional Scaffold for Myocardial Infarction Repair

Engineering cardiac patches are proven to be effective in myocardial infarction (MI) repair, but it is still a tricky problem in tissue engineering to construct a scaffold with good biocompatibility, suitable mechanical properties, and solid structure. Herein, decellularized fish skin matrix is utilized with good biocompatibility to prepare a flexible conductive cardiac patch through polymerization of polydopamine (PDA) and polypyrrole (PPy). Compared with single modification, the double modification strategy facilitated the efficiency of pyrrole polymerization, so that the patch conductivity is improved. According to the results of experiments in vivo and in vitro, the scaffold can promote the maturation and functionalization of cardiomyocytes (CMs). It can also reduce the inflammatory response, increase local microcirculation, and reconstruct the conductive microenvironment in infarcted myocardia, thus improving the cardiac function of MI rats. In addition, the excellent flexibility of the scaffold, which enables it to be implanted in vivo through “folding-delivering-re-stretehing” pathway, provides the possibility of microoperation under endoscope, which avoids the secondary damage to myocardium by traditional thoracotomy for implantation surgery.     

Shrunken centroids regularized discriminant analysis as a promising strategy for metabolomics data exploration

Metabolomics datasets generated by modern analytical instruments tend to be increasingly complex. In this study, a recent method named shrunken centroids regularized discriminant analysis (SCRDA) has been introduced and applied in the exploration of metabolomics dataset. It is a supervised method for variable selection, discriminant analysis and biomarker screening. By regularizing the estimate of the within‐class covariance matrix, SCRDA can deal with the singularity issue of linear discriminant analysis. Then a shrinkage estimator is applied to perform variable selection. The method presented is illustrated through the simulated datasets and three complex metabolomics datasets. Commonly used orthogonal partial least squares discriminant analysis and two other similar statistical methods, penalized linear discriminant analysis and nearest shrunken centroids, are used for comparisons. The results illustrate that SCRDA has some desirable abilities in variable selection, classification and prediction. Moreover, the biomarkers identified by SCRDA are further demonstrated to be in accordance with the biochemical research. It has been proved that SCRDA can be applied as a promising strategy in metabolomics. Copyright © 2014 John Wiley & Sons, Ltd.     

Plasma metabolomic profile and potential biomarkers for missed abortion

A missed abortion (MA) is an in utero death of the embryo or fetus before the 20th week of gestation with retained products of conception, and this condition is currently common in China. In order to discover novel biomarkers for MA, ultrahigh performance liquid chromatography was applied to study plasma metabolite profiles for 33 patients with MA and 29 control subjects. Thirty‐seven differential plasma metabolites were found to discriminate between the two groups in the initial cohort (15 subjects with MA and 15 healthy controls). The feasibility of using these potential biomarkers to predict MA was further evaluated in the validation cohort (18 subjects with MA and 14 healthy controls) and 15 had an area under the receiver operating characteristic curve of >0.80, making them satisfactory. Tryptophan metabolism and sphingolipid metabolism were identified as important potential target pathways for MA using metabolic pathway impact analysis. Furthermore, three of the 15 satisfactory metabolites (glyceric acid, indole and sphingosine) were combined to establish a predictive model with 100% sensitivity and 100% specificity in the validation cohort. Taken together, these results suggest that MA results in significant disturbance of metabolism and those various novel biomarkers have satisfactory diagnostic and predictive power for MA.     

1H NMR‐based metabolomics exploring urinary biomarkers correlated with proteinuria in focal segmental glomerulosclerosis: a pilot study

Focal segmental glomerulosclerosis (FSGS) is a common glomerulonephritis, and its rates of occurrence are increasing worldwide. Proteinuria is a clinical defining feature of FSGS which correlates with the severity of podocyte injury in patients with nephrotic‐range protein excretion. Metabolite biomarkers corresponding with the level of proteinuria could be considered as non‐invasive complementary prognostic factors to proteinuria. The urine samples of 15 patients (n = 6 women and n = 9 men) with biopsy‐proven FSGS were collected and subjected to nuclear magnetic resonance (NMR) analysis for metabolite profiling. Multivariate statistical analyses, including principal component analysis and orthogonal projection to latent structure discriminant analysis, were applied to construct a predictive model based on patients with proteinuria >3000 mg/day and <3000 mg/day. In addition, random forest was performed to predict differential metabolites, and pathway analysis was performed to find the defective pathways responsible for proteinuria. Ten metabolites, significant in both statistical methods (orthogonal projection to latent structure discriminant analysis and random forest), were considered as prognostic biomarkers for FSGS: citrulline, dimethylamine, proline, acetoacetate, alpha‐ketoisovaleric acid, valine, isobutyrate, D‐Palmitylcarnitine, histidine, and N‐methylnicotinamide. Pathway analysis revealed impairment of the branched‐chain amino acid degradation pathways in patients with massive proteinuria. This study shows that metabolomics can reveal the molecular changes corresponding with disease progression in patients with FSGS and provide a new insight for pathogenic pathways. Copyright © 2016 John Wiley & Sons, Ltd.     

Human emotions detection based on a smart-thermal system of thermographic images

This work presents a noninvasive methodology to obtain biomedical thermal imaging which provide relevant information that may assist in the diagnosis of emotions. Biomedical thermal images of the facial expressions of 44 subjects were captured experiencing joy, disgust, anger, fear and sadness. The analysis of these thermograms was carried out through its thermal value not with its intensity value. Regions of interest were obtained through image processing techniques that allow to differentiate between the subject and the background, having only the subject, the centers of each region of interest were obtained in order to get the same region of the face for each subject. Through the thermal analysis a biomarker for each region of interest was obtained, these biomarkers can diagnose when an emotion takes place. Because each subject tends to react differently to the same stimuli, a self-calibration phase is proposed, its function is to have the same thermal trend for each subject in order to make a decision so that the five emotions can be correctly diagnosed through a top-down hierarchical classifier. As a final result, a smart-thermal system that diagnose emotions was obtained and it was tested on twenty-five subjects (625 thermograms). The results of this test were 89.9% successful.     

Label‐free Electrochemical Immunosensor for Cardiac Troponin T Based on Exfoliated Graphite Nanoplatelets Decorated with Gold Nanoparticles

This paper describes the application of exfoliated graphite nanoplatelets (xGnP) decorated with gold nanoparticles (AuNP) for the development of a label‐free electrochemical immunosensor for the determination of human cardiac troponin T (TnT), an important cardiac biomarker in the diagnosis of acute myocardial infarction (AMI). Heparin‐stabilized AuNP (AuNP‐Hep) were synthesized, characterized and supported on xGnP. The material obtained (AuNP‐Hep‐xGnP) was used as a platform to immobilize the anti‐TnT by adsorption and this was then applied in the construction of an immunosensor. Under optimized conditions, using differential pulse voltammetry (DPV) and an incubation time of 20 min, the proposed immunosensor showed linearity in the range of 0.050 to 0.35 ng mL⁻¹ TnT, with a calculated limit of detection of 0.016 ng mL⁻¹. The interday precision (n=7) showed a coefficient of variation of 6.5 %. Some potential interferents commonly present in blood plasma samples were investigated and the degree of interference was found to be low (less than 10 %), demonstrating adequate selectivity for analytical applications. The biosensor was successfully applied in the determination of TnT in fortified samples of human blood plasma.