Vericiguat in heart failure: From scientific evidence to clinical practice.

Despite currently available treatments, risk of death and hospitalizations in patients with heart failure with reduced ejection fraction (HFrEF) remains high. The pathophysiology of HFrEF includes neurohormonal activation characterized by stimulation of deleterious pathways (i.e., sympathetic nervous and renin-angiotensin-aldosterone systems) and suppression of protective pathways such as nitric oxide-dependent pathways. Inhibition or stimulation of some, but not all, of these pathways is insufficient. In HFrEF, there is reduced nitric oxide, soluble guanylate cyclase, and cGMP activity, leading to deleterious effects in the myocardial, vascular, and renal systems. Vericiguat is able to stimulate the activity of this protective pathway. The VICTORIA study demonstrated that the addition of vericiguat to optimal medical treatment in patients with HFrEF and recent decompensation significantly reduced the incidence of the primary endpoint, a composite of cardiovascular death or HF hospitalization, with a number needed to treat of 24 patients and excellent tolerability.

Particle size and cholesterol content of circulating HDL correlate with cardiovascular death in chronic heart failure.

Evidence regarding any association of HDL-particle (HDL-P) derangements and HDL-cholesterol content with cardiovascular (CV) death in chronic heart failure (HF) is lacking. To investigate the prognostic value of HDL-P size (HDL-Sz) and the number of cholesterol molecules per HDL-P for CV death in HF patients. Outpatient chronic HF patients were enrolled. Baseline HDL-P number, subfractions and HDL-Sz were measured using 1H-NMR spectroscopy. The HDL-C/P ratio was calculated as HDL-cholesterol over HDL-P. Endpoint was CV death, with non-CV death as the competing event. 422 patients were included and followed-up during a median of 4.1 (0-8) years. CV death occurred in 120 (30.5%) patients. Mean HDL-Sz was higher in CV dead as compared with survivors (8.39 nm vs. 8.31 nm, p < 0.001). This change in size was due to a reduction in the percentage of small HDL-P (54.6% vs. 60% for CV-death vs. alive; p < 0.001). HDL-C/P ratio was higher in the CV-death group (51.0 vs. 48.3, p < 0.001). HDL-Sz and HDL-C/P ratio were significantly associated with CV death after multivariable regression analysis (HR 1.22 [95% CI 1.01-1.47], p = 0.041 and HR 1.04 [95% CI 1.01-1.07], p = 0.008 respectively). HDL-Sz and HDL-C/P ratio are independent predictors of CV death in chronic HF patients.

Differences in the Interleukin-1ß/Soluble ST2 Interplay Between Acute and Chronic Heart Failure.

Recently, novel findings about the interleukin 1ß (IL-1 ß) axis in acute decompensated heart failure (ADHF) have been published. There is a positive correlation between IL-1 ß and interleukin-1 receptor like 1 (sST2) in ADHF patients. Is there also a correlation between the values of IL-1 ß and sST2 in chronic heart failure patients?

Growth differentiation factor-15 is a predictive biomarker in primary ventricular fibrillation: The RUTI-STEMI-PVF study.

BACKGROUND: Primary ventricular fibrillation is an ominous complication of ST-segment elevation myocardial infarction, and proper biomarkers for risk prediction are lacking. Growth differentiation factor-15 is a marker of inflammation, oxidative stress and hypoxia with well-established prognostic value in ST-segment elevation myocardial infarction patients. We explored the predictive value of growth differentiation factor-15 in a subgroup of ST-segment elevation myocardial infarction patients with primary ventricular fibrillation. METHODS: Prospective registry of ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention from February 2011-August 2015. Growth differentiation factor-15 concentrations were measured on admission. Logistic regression and Cox proportional regression analyses were used. RESULTS: A total of 1165 ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention (men 78.5%, age 62.3±13.1 years) and 72 patients with primary ventricular fibrillation (6.2%) were included. Compared to patients without primary ventricular fibrillation, median growth differentiation factor-15 concentration was two-fold higher in ST-segment elevation myocardial infarction patients with primary ventricular fibrillation (2655 vs 1367 pg/ml, p<0.001). At 30 days, mortality was 13.9% and 3.6% in patients with and without primary ventricular fibrillation, respectively (p<0.001), and median growth differentiation factor-15 concentration in patients with primary ventricular fibrillation was five-fold higher among those who died vs survivors (13,098 vs 2415 pg/ml, p<0.001). In a comprehensive multivariable analysis including age, sex, clinical variables, reperfusion time, left ventricular ejection fraction, N-terminal pro-B-type natriuretic peptide and high-sensitivity troponin T, growth differentiation factor-15 remained an independent predictor of 30-day mortality, with odds ratios of 3.92 (95% confidence interval 1.35-11.39) in patients with primary ventricular fibrillation (p=0.012) and 1.72 (95% confidence interval 1.23-2.40) in patients without primary ventricular fibrillation (p=0.001). CONCLUSIONS: Growth differentiation factor-15 is a robust independent predictor of 30-day mortality in ST-segment elevation myocardial infarction patients with primary ventricular fibrillation.

Yin-Yang 1 transcription factor modulates ST2 expression during adverse cardiac remodeling post-myocardial infarction.

BACKGROUND: The cardioprotective effects of metformin remain poorly defined. Interleukin (IL)-33/ST2L signaling is a novel cardioprotective pathway, which is antagonized by the soluble isoform sST2. No data exist about the regulation of ST2 expression. This study aimed to evaluate the pathophysiological implication of Yin-Yang 1 (Yy1) transcription factor in cardiac remodeling and the expression of the soluble ST2 isoform. METHODS AND RESULTS: Myocardial infarction (MI) was induced in Wistar rats randomly receiving metformin or saline solution by permanent ligation of the left anterior coronary artery. In addition, a model of cardiomyocyte "biochemical strain" was used. Metformin administration improved post-MI cardiac remodeling, an effect that was associated with increased IL-33 and reduced sST2 levels in the myocardium. The anti-remodeling effects of metformin were also associated with a decrease in the transcription factor Yy1 intranuclear level and lower levels of phosphorylated HDAC4 within the cytoplasmic space. These effects were also observed in a cardiomyocyte biochemical strain model, where Yy1 silencing or HDAC4 inhibition blocked sST2 production in cardiomyocytes. Metformin blocked the HDAC4 phosphorylation induced by MI, preventing its export from the nucleus to the cytosol. The presence of dephosphorylated HDAC4 in the nucleus acted as a co-repressor of Yy1, repressing sST2 expression. CONCLUSION: The transcription factor Yy1 regulates sST2 expression, and repression of Yy1 by metformin results in lower levels of sST2 that are associated with favorable myocardial remodeling. The manipulation of YY1 or its co-repressor HDAC4 emerge as new targets to modulate ST2/IL33 signaling and prevent adverse cardiac remodeling.

Variable endothelial cell function restoration after initiation of two antiretroviral regimens in HIV-infected individuals.

Background: The effect of ART on endothelial cell function is incompletely characterized. Methods: We performed a 24 week prospective, case-control and comparative pilot study of ART-naive HIV-infected patients who started a darunavir- or rilpivirine-based regimen, matched with non-HIV-infected volunteers, to compare changes at week 24 from baseline in levels of circulating endothelial cells (CECs), endothelial progenitor cells (EPCs) and circulating angiogenic cells, as well as changes in immune-activation markers. Results: The study population comprised 24 HIV-infected patients and 24 non-infected volunteers. Both HIV groups completely suppressed viraemia. HIV-infected patients had higher levels of activation markers than the control group in CD8 T cells at baseline; these decreased after 24 weeks of treatment, but without reaching the levels of the control group. No statistical differences in immune activation were seen between the darunavir and rilpivirine groups. Levels of CECs were higher and levels of EPCs and circulating angiogenic cells were lower in HIV-infected patients than in the control group, although these parameters were similar between the darunavir group and the control group, but not the rilpivirine group, at week 24. An unfavourable association was observed between rilpivirine, age and increased number of CECs. Conclusions: Restoration of circulating levels of EPCs and CECs in darunavir-treated patients was greater than in those treated with rilpivirine, suggesting ongoing endothelial repair mechanisms.

Conformational and thermal characterization of left ventricle remodeling post-myocardial infarction.

Adverse cardiac remodeling after myocardial infarction (MI) causes impaired ventricular function and heart failure. Histopathological characterization is commonly used to detect the location, size and shape of MI sites. However, the information about chemical composition, physical structure and molecular mobility of peri- and infarct zones post-MI is rather limited. The main objective of this work was to explore the spatiotemporal biochemical and biophysical alterations of key cardiac components post-MI. The FTIR spectra of healthy and remote myocardial tissue shows amides A, I, II and III associated with proteins in freeze-died tissue as major absorptions bands. In infarcted myocardium, the spectrum of these main absorptions was deeply altered. FITR evidenced an increase of the amide A band and the distinct feature of the collagen specific absorption band at 1338cm-1 in the infarct area at 21days post-MI. At 21days post-MI, it also appears an important shift of amide I from 1646cm-1 to 1637cm-1 that suggests the predominance of the triple helical conformation in the proteins. The new spectra bands also indicate an increase in proteoglycans, residues of carbohydrates in proteins and polysaccharides in ischemic areas. Thermal analysis indicates a deep increase of unfreezable water/freezable water in peri- and infarcted tissues. In infarcted tissue is evidenced the impairment of myofibrillar proteins thermal profile and the emergence of a new structure. In conclusion, our results indicate a profound evolution of protein secondary structures in association with collagen deposition and reorganization of water involved in the scar maturation of peri- and infarct zones post-MI.

Consensus document and recommendations on the use of natriuretic peptides in clinical practice. / Documento de consenso y recomendaciones sobre el uso de los péptidos natriuréticos en la práctica clínica.

Natriuretic peptides are a useful laboratory tool for the diagnosis, prognosis and treatment of patients with heart failure. Natriuretic peptides are used in various healthcare settings (consultations, emergency department, hospitalization, laboratory) and by various primary care and specialised professionals. However, their use in clinical practice is still scare and uneven. Properly using and interpreting natriuretic peptides in clinical practice requires a minimum of prelaboratory (pathophysiology), laboratory (methods) and postlaboratory (interpretation and integration of clinical data) expertise. The objective of this consensus document, developed by several scientific societies, is to update the necessary concepts and expertise on natriuretic peptides that enable its application in the diagnosis, prognosis and treatment of heart failure, in various healthcare environments.

Circulating soluble low-density lipoprotein receptor-related protein 1 (sLRP1) concentration is associated with hypercholesterolemia: A new potential biomarker for atherosclerosis.

BACKGROUND: There is clinical interest in identifying novel lipid biomarkers for evaluating cardiovascular risk and targeting lipid-lowering treatment. Low-density lipoprotein receptor-related protein 1 (LRP1) plays a crucial role in the dysregulated cholesterol transfer from modified lipoproteins to human coronary vascular smooth muscle cells (hVSMCs), promoting hVSMC-derived foam cell formation. LRP1 has a soluble and circulating form (sLRP1) generated from LRP1. Cholesterol modulates the release of the soluble form of LRP1. Using in vitro, ex vivo and patient-based approaches, we tested the association between circulating sLRP1 concentrations and hypercholesterolemia and the potential of sLRP1 as a biomarker of atherosclerosis. METHODS AND RESULTS: Circulating sLRP1 concentrations were higher in severe hypercholesterolemia compared to moderate hypercholesterolemia or normocholesterolemia (Study 1). Circulating sLRP1 was significantly associated with established pro-atherogenic lipid parameters in two different hypercholesterolemic populations (Studies 2 and 3). sLRP1 concentrations decreased after statin treatment and increased after statin withdrawal (Study 3). In vitro experiments showed that native LDL, aggregated LDL and VLDL+IDL lipoproteins induced the release of sLRP1 from hVSMC. sLRP1 levels were increased in the conditioned medium of coronary atherosclerotic plaque areas extracted from patients compared to non-atherosclerotic areas of the same coronary artery and patient. Circulating sLRP1 concentrations were independently associated with the occurrence of carotid atherosclerosis in a hypercholesterolemic population (Study 2). The later association was higher than that observed for other classical or novel lipid parameters. CONCLUSIONS: Circulating sLRP1 is a new lipid-related parameter potentially useful as a biomarker for atherosclerosis.

Electrical stimulation of cardiac adipose tissue-derived progenitor cells modulates cell phenotype and genetic machinery.

A major challenge of cardiac tissue engineering is directing cells to establish the physiological structure and function of the myocardium being replaced. Our aim was to examine the effect of electrical stimulation on the cardiodifferentiation potential of cardiac adipose tissue-derived progenitor cells (cardiac ATDPCs). Three different electrical stimulation protocols were tested; the selected protocol consisted of 2 ms monophasic square-wave pulses of 50 mV/cm at 1 Hz over 14 days. Cardiac and subcutaneous ATDPCs were grown on biocompatible patterned surfaces. Cardiomyogenic differentiation was examined by real-time PCR and immunocytofluorescence. In cardiac ATDPCs, MEF2A and GATA-4 were significantly upregulated at day 14 after stimulation, while subcutaneous ATDPCs only exhibited increased Cx43 expression. In response to electrical stimulation, cardiac ATDPCs elongated, and both cardiac and subcutaneous ATDPCs became aligned following the linear surface pattern of the construct. Cardiac ATDPC length increased by 11.3%, while subcutaneous ATDPC length diminished by 11.2% (p = 0.013 and p = 0.030 vs unstimulated controls, respectively). Compared to controls, electrostimulated cells became aligned better to the patterned surfaces when the pattern was perpendicular to the electric field (89.71 ± 28.47º for cardiac ATDPCs and 92.15 ± 15.21º for subcutaneous ATDPCs). Electrical stimulation of cardiac ATDPCs caused changes in cell phenotype and genetic machinery, making them more suitable for cardiac regeneration approaches. Thus, it seems advisable to use electrical cell training before delivery as a cell suspension or within engineered tissue.

The obesity paradox in heart failure patients with preserved versus reduced ejection fraction: a meta-analysis of individual patient data.

BACKGROUND: In heart failure (HF), obesity, defined as body mass index (BMI) ≥30 kg m(-2), is paradoxically associated with higher survival rates compared with normal-weight patients (the 'obesity paradox'). We sought to determine if the obesity paradox differed by HF subtype (reduced ejection fraction (HF-REF) versus preserved ejection fraction (HF-PEF)). PATIENTS AND METHODS: A sub-analysis of the MAGGIC meta-analysis of patient-level data from 14 HF studies was performed. Subjects were divided into five BMI groups: <22.5, 22.5-24.9 (referent), 25-29.9, 30-34.9 and ≥35 kg m(-2). Cox proportional hazards models adjusted for age, sex, aetiology (ischaemic or non-ischaemic), hypertension, diabetes and baseline blood pressure, stratified by study, were used to examine the independent association between BMI and 3-year total mortality. Analyses were conducted for the overall group and within HF-REF and HF-PEF groups. RESULTS: BMI data were available for 23 967 subjects (mean age, 66.8 years; 32% women; 46% NYHA Class II; 50% Class III) and 5609 (23%) died by 3 years. Obese patients were younger, more likely to receive cardiovascular (CV) drug treatment, and had higher comorbidity burdens. Compared with BMI levels between 22.5 and 24.9 kg m(-2), the adjusted relative hazards for 3-year mortality in subjects with HF-REF were: hazard ratios (HR)=1.31 (95% confidence interval=1.15-1.50) for BMI <22.5, 0.85 (0.76-0.96) for BMI 25.0-29.9, 0.64 (0.55-0.74) for BMI 30.0-34.9 and 0.95 (0.78-1.15) for BMI ≥35. Corresponding adjusted HRs for those with HF-PEF were: 1.12 (95% confidence interval=0.80-1.57) for BMI <22.5, 0.74 (0.56-0.97) for BMI 25.0-29.9, 0.64 (0.46-0.88) for BMI 30.0-34.9 and 0.71 (0.49-1.05) for BMI ≥35. CONCLUSIONS: In patients with chronic HF, the obesity paradox was present in both those with reduced and preserved ventricular systolic function. Mortality in both HF subtypes was U-shaped, with a nadir at 30.0-34.9 kg m(-2).

Low density lipoprotein receptor-related protein 1 is upregulated in epicardial fat from type 2 diabetes mellitus patients and correlates with glucose and triglyceride plasma levels.

Lipoprotein receptor expression plays a crucial role in the pathophysiology of adipose tissue in in vivo models of diabetes. However, there are no studies in diabetic patients. The aims of this study were to analyze (a) low-density lipoprotein receptor-related protein 1 (LRP1) and very low-density lipoprotein receptor (VLDLR) expression in epicardial and subcutaneous fat from type 2 diabetes mellitus compared with nondiabetic patients and (b) the possible correlation between the expression of these receptors and plasmatic parameters. Adipose tissue biopsy samples were obtained from diabetic (n = 54) and nondiabetic patients (n = 22) undergoing cardiac surgery before the initiation of cardiopulmonary bypass. Adipose LRP1 and VLDLR expression was analyzed at mRNA level by real-time PCR and at protein level by Western blot analysis. Adipose samples were also subjected to lipid extraction, and fat cholesterol ester, triglyceride, and free cholesterol contents were analyzed by thin-layer chromatography. LRP1 expression was higher in epicardial fat from diabetic compared with nondiabetic patients (mRNA 17.63 ± 11.37 versus 7.01 ± 4.86; P = 0.02; protein 11.23 ± 7.23 versus 6.75 ± 5.02, P = 0.04). VLDLR expression was also higher in epicardial fat from diabetic patients but only at mRNA level (231.25 ± 207.57 versus 56.64 ± 45.64, P = 0.02). No differences were found in the expression of LRP1 or VLDLR in the subcutaneous fat from diabetic compared with nondiabetic patients. Epicardial LRP1 and VLDLR mRNA overexpression positively correlated with plasma triglyceride levels (R(2) = 0.50, P = 0.01 and R(2) = 0.44, P = 0.03, respectively) and epicardial LRP1 also correlated with plasma glucose levels (R(2) = 0.33, P = 0.03). These results suggest that epicardial overexpression of certain lipoprotein receptors such as LRP1 and VLDLR expression may play a key role in the alterations of lipid metabolism associated with type 2 diabetes mellitus.

Common health problems management uncertainties in heart failure: a qualitative study.

BACKGROUND: Medicine review with follow up quantitative studies conducted on heart failure (HF) outpatients detected health problems that were frequently treated insufficiently: hyperuricemia, gastric injury prevention, anemia, and diabetes mellitus. OBJECTIVE: The aim of this qualitative study was to explore experiences in the pharmacological management of these health problems, and to contribute with strategies to overcome the identified obstacles. METHODS: The internal medicine specialists and cardiologists of a tertiary hospital HF clinic underwent in-depth semi-structured interviews and a constant comparative approach was used. RESULTS: Interviewees highlighted there is a lack of guidelines concerning the treatment of asymptomatic hyperuricemia in HF, thus in routine practice it is often not treated. Interviewees said that preventive strategies to avoid gastric injury in at-risk patients taking prophylactic low-dose aspirin are needed, but the most appropriate strategy is not well defined. Interviewees thought that structural support is needed for the management of HF patients with anemia, and proper clinic pathways should be created to identify which service patients should be referred to. The same lack of communication with other services appeared with diabetes mellitus. CONCLUSION: HF specialists demand a closer interaction with other specialists for a comprehensive approach to these polymedicated patients with multiple co-morbidities. And suggest that specific recommendations in HF guidelines to manage these co-morbidities specifically in HF would be helpful to shed light upon the existing confusing evidence.

Towards on line monitoring the evolution of the myocardium infarction scar with an implantable electrical impedance spectrum monitoring system.

The human heart tissue has a limited capacity for regeneration. Tissue and cellular therapies based on the use of stem cells may be useful alternatives to limit the size of myocardial infarction. In this paper, the preliminary results from an experimental campaign for on-line monitoring of myocardium scar infarction are presented. This study has been carried out under a research project that has as main objective the development and application of a bioactive patch implant for regeneration of myocardial infarction. Electrical Impedance Spectroscopy (EIS) has been chosen as a tissue state monitoring technique. What is presented in this communication is the first results of an implantable EIS measurement system which has been implanted in a subset of the animals corresponding to the control group, along one month. In all the animals, the myocardial infarction was induced by the ligation of the first circumflex marginal artery. In the animal group presented, the bioactive patch scaffold and the electrodes were implanted without the stem cells load. The scaffold is a piece of decellularized human pericardium, lyophilized and rehydrated with hydrogel RAD16-I. Nanogold particles were also placed near the electrodes to improve the electrode area conductivity. The results presented correspond to the subset of animals (n = 5), which had implanted the bioimpedance system monitoring the electrical impedance spectrum in vivo during 1 month. Two electrodes were connected to the bioactive patch implant. A total of 14 logarithmically spaced frequencies were measured every 5 minutes, from 100 Hz to 200 kHz. Results show a convergence of low-frequency and high frequency impedance magnitudes along the measurement period, which is coherent with the scar formation.

Correlation between myocardial fibrosis and the occurrence of atrial fibrillation in hypertrophic cardiomyopathy: a cardiac magnetic resonance imaging study.

Cardiac magnetic resonance imaging (CMR) in hypertrophic cardiomyopathy (HCM) often shows delayed contrast enhancement (DE) representing regions of focal myocardial fibrosis. Atrial fibrillation (AF) is a commonly reported complication of HCM. We determined the relationship between the presence of left ventricular myocardial fibrosis (LVMF) detected by DE-CMR and the occurrence AF in a series of patients with HCM. 67 patients with HCM (47 males; mean age 50.1+/-18.5 years) were studied by CMR measuring mass of LVMF, left ventricular mass, volume and function, and left atrial (LA) area. AF was present in 17 (25%) patients. LVMF was observed in 57% of patients. AF was significantly more frequent in patients who also showed LVMF, compared with the group without LVMF (42.1% vs. 3.4%, respectively; p<0.0001). LA size was larger in patients showing DE (LA area: 37.4+/-11.1 vs. 25.9+/-6.8 cm(2); respectively, p=0.0001). AF in HCM is related with myocardial fibrosis detected by DE-CMR and dilatation of the LA. This fact adds to the proven adverse prognostic value of myocardial fibrosis in HCM, thus, reinforcing the usefulness of this technique in the assessment of these patients.

Cardiomyogenic differentiation of human bone marrow mesenchymal cells: Role of cardiac extract from neonatal rat cardiomyocytes.

Bone marrow mesenchymal stromal cells (BM-MSCs) with regenerative potential have been identified in heart. Whether these cells become new cardiac lineage cells by phenomena of transdifferentiation or fusion is also being investigated. Although, these mechanisms give cardiomyocytes, it has to be considered that MSCs transplantation could carry out ossification and calcification processes. An alternative might be the use of myocytes; however, the problem is the arrythmia. For those reasons, is that we investigated how to obtain cardiomyocyte-like cells from human MSCs (hMSCs). The aim of the present work was to evaluate a nuclear reprogramming of the hMSCs by a neonatal rat cardiomyocytes extract (EX) using Streptolysin O (SLO) treatment. hMSCs treated with 57.5ng/ml SLO presented ball-like, stick-like and myotube-like morphology. In the absence of cardiomyogenic stimuli, hMSCs expressed markers of cardiac phenotype-like sarcomeric alpha-actinin, connexin-43 and GATA-4. However, when hMSCs were treated with SLO+EX or 10 microM of 5-azacytidine (5-AZA), the expression of these markers were significantly increased and furthermore, expressed SERCA-2, cardiac Troponin I, beta-MyHC, desmin, MLC-2a and MLC-2v thus showing the phenotype of mature cardiomyocytes. PCR analysis showed that cardiomyocyte-related genes, such as beta1-adrenergic receptor (beta1-AR), MLC-2a and cardiac Troponin T, were expressed after SLO+EX treatment like with 5-AZA. We concluded that the extract of neonatal rat cardiomyocytes could promote a nuclear modification of hMSCs to cardiomyogenic-like cells differentiation. Since the 5-AZA treatment appears to be genotoxic and taking into account the obtained results, the nuclear reprogramming by cell extract may be an approach leading to the identification of soluble factors that drives the reprogramming.

Implantable bioimpedance monitor using ZigBee.

In this paper, a novel implantable bioimpedance monitor using a free ZigBee protocol for the transmission of the measured data is described. The application field is the tissue and organ monitoring through electrical impedance spectroscopy in the 100 Hz - 200 kHz range. The specific application is the study of the viability and evolution of engineered tissue in cardiac regeneration. Additionally to the telemetric feature, the measured data are stored in a memory for backup purposes and can be downloaded at any time after an RF link break. In the debugging prototype, the system autonomy exceeds 1 month when a 14 frequencies impedance spectrum is acquired every 5 minutes. In the current implementation, the effective range of the RF link is reduced and needs for a range extender placed near the animal. Current work deals with improving this range.

Hemosiderin deposits confounds tracking of iron-oxide-labeled stem cells: an experimental study.

BACKGROUND: The aim of the present research was to study the possible interference of hemosiderin deposits with the histological detection of dextran-coated, iron-labeled, mesenchymal stem cells after intracoronary administration in a porcine model of myocardial infarction. MATERIALS AND METHODS: A myocardial infarction was induced in six animals that received intracoronary iron-labeled autologous mesenchymal stem cells (group 1; n = 2) or placebo (group 2; n = 4). Six control animals without myocardial infarction underwent direct intramyocardial injections of iron-labeled autologous mesenchymal stem cells (group 3; n = 2) or placebo (group 4; n = 4). Histological sections from explanted hearts were stained with Prussian blue to identify dextran-coated, iron-labeled, mesenchymal stem cells. RESULTS: After Prussian blue staining, granular blue labeling in the tissue was observed in both groups of animals with infarcts. Similar granular blue labeling was detected in hearts from control animals without infarction that had received iron-labeled mesenchymal stem cells. However, hearts from control animals without infarction that received placebo did not have any granular blue labeling in the tissue. CONCLUSIONS: Hemosiderin from infarction hemorrhage interferes with detection of dextran-coated iron-labeled mesenchymal stem cells after intracoronary administration, suggesting that this marker is not useful to detect mesenchymal stem cells in a porcine model of myocardial infarction.

Analysis of respiratory flow signals in chronic heart failure patients with periodic breathing.

In patients with chronic heart failure (CHF), oscillatory breathing pattern predicts poor prognosis. This work proposes a method to identify the respiratory pattern to determine periodic breathing (PB), Cheyne-Stokes respiration (CSR) and non-periodic respiratory patterns (nPB) through the respiratory flow signal. 26 patients are studied, classified in G(1) (PB), G(2) (CSR) and G(3) (nPB). The flow signal is filtered and normalized, to obtain the positive envelope that describes the respiratory pattern. With this new signal some features are extracted through its power spectral density (PSD). An adaptive feature selection algorithm is applied before the linear and non linear classification applying Leave-one-out cross-validation technique. The result obtained with linear classification was 93% using the relation between total energy and frequency interval (I(1)), peak amplitude (ampp), peak frequency (fp), and the highest slope of the positive envelope's PSD (Slope(max)). And the best result was obtained with non linear technique, with 100% correctly classified patients, using only two parameters, fp and Slope(max).