Monitoring of plasma circulating donor DNA reflects cardiac graft injury: Report of two cases

The current standard for graft rejection surveillance is endomyocardial biopsy (EMB), an invasive procedure with rare but potentially serious complications. Detection of circulating donor-derived cell-free DNA (ddcfDNA) is an option for noninvasive monitoring of graft injury and rejection. A 63-year-old man and a 65-year-old woman were monitored by EMB for allograft rejection. A total of 48 single-nucleotide polymorphisms with a minor allele frequency range of 0.4-0.5 were screened to distinguish donor and recipient DNA based on homozygosity, and digital droplet PCR was used to analyze ddcfDNA concentrations. Both subjects suffered rejection within the first 6 months after transplantation. The maximal ddcfDNA level of 270 copies (cp)/ml during EMB-confirmed acute cellular rejection (ACR; mild grade 1R/2, patient 1), and the maximal concentration of 1,846 cp/ml in the case of EMB-confirmed antibody-mediated rejection (AMR; grade 1+; patient 2), was detected. Individual monitoring of ddcfDNA dynamics from the 1st to the 6th month posttransplant reflected cardiac graft injury in patients suffering ACR or AMR, meaning that ddcfDNA may serve as a noninvasive biomarker.

The effect of long-term left ventricular assist device support on flow-sensitive plasma microRNA levels

BACKGROUND

Implantation of current generation left ventricular assist devices (LVADs) in the treatment of end-stage heart failure (HF), not only improves HF symptoms and end-organ perfusion, but also leads to cellular and molecular responses, presumably in response to the continuous flow generated by these devices. MicroRNAs (miRNAs) are important post-transcriptional regulators of gene expression in multiple biological processes, including the pathogenesis of HF. In our study, we examined the influence of long-term LVAD support on changes in flow-sensitive miRNAs in plasma.

MATERIALS AND METHODS

Blood samples from patients with end-stage heart failure (N = 33; age = 55.7 ± 11.6 years) were collected before LVAD implantation and 3, 6, 9, and 12 months after implantation. Plasma levels of the flow-sensitive miRNAs; miR-10a, miR-10b, miR-146a, miR-146b, miR-663a, miR-663b, miR-21, miR-155, and miR-126 were measured using quantitative PCR.

RESULTS

Increasing quantities of miR-126 (P < 0.03) and miR-146a (P < 0.02) was observed at each follow-up visit after LVAD implantation. A positive association between miR-155 and Belcaro score (P < 0.04) and an inverse correlation between miR-126 and endothelial function, measured as the reactive hyperemia index (P < 0.05), was observed.

CONCLUSIONS

Our observations suggest that after LVAD implantation, low pulsatile flow up-regulates plasma levels of circulating flow-sensitive miRNAs, contributing to endothelial dysfunction and vascular remodeling.

The Effect of Artificial Pulsatility on the Peripheral Vasculature in Patients with A Continuous-Flow Ventricular Assist Device

BACKGROUND

Implantation of left ventricular assist systems (LVASs) has become the standard of care for advanced heart failure (HF). The absence of pulsatility in previous devices contributes to vascular and endothelial dysfunction, related to atherosclerotic or vascular complications. We hypothesized that the artificial pulsatility provided by the HeartMate 3 (HM3) LVAS would exert a favorable effect on the vasculature.

METHODS

In 32 patients implanted with HM3 (5 females; mean age 55±13.6 years), the reactive hyperemia index (RHI) and peripheral augmentation index (AI), markers of endothelial function and arterial stiffness, were measured with an Endo-PAT2000 prior to and in the 3^rd and 6^th months after implantation. RHI and AI data from 30 HeartMate II (HM II) recipients in the 3^rd and 6^th months after implantation, from 15 advanced HF patients without LVASs, and from 13 healthy volunteers were also analyzed.

RESULTS

In HM3 recipients, the mean RHI significantly decreased at 3^rd and 6^th months after implantation. The RHI was substantially lower at baseline than that of healthy or HF reference group. Increasing AI values, indicating worsening arterial stiffness, were also observed. Similar trends were observed in HM II recipients between the 3^rd and 6^th months, but with higher absolute values of RHI and AI.

CONCLUSIONS

We detected impaired vascular function in HM3 patients and provided additional evidence on the negative effect of low pulsatility on vascular function after LVAS implantation. The results suggest that the artificial pulsatility of the HM3 does not avert the progression of endothelial dysfunction.

Hypertension-related intermyocyte junction remodelling is associated with a higher incidence of low-K(+)-induced lethal arrhythmias in isolated rat heart

The aim of this study was to characterise the arrhythmogenic mechanisms involved in hypokalaemia-induced sustained ventricular fibrillation (SVF), in hypertensive rats. The hearts from rats with hypertension induced by the nitric oxide synthase inhibitor L-NAME, and age-matched normotensive controls, were perfused in Langendorff mode with oxygenated Krebs-Henseleit solution followed by a K(+)-deficient solution. In additional experiments, free intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2 in conjunction with an epicardial optical probe. The epicardial electrocardiogram was continuously monitored during all experiments. The gap junction protein connexin-43 and the ultrastructure of the cardiomyocytes were examined, and selected enzyme activities were measured in situ. There was a higher incidence of low-K(+)-induced SVF in the hearts of hypertensive compared to normotensive rats (83 % vs. 33 %, P < 0.05). Perfusion with a low-K(+)-containing solution lead to elevation of diastolic [Ca(2+)](i) that was accompanied by premature beats, bigeminy, ventricular tachycardia and transient ventricular fibrillation. These events occurred earlier with increased incidence and duration in the hearts of hypertensive rats (arrhythmia scores: hypertensive, 4.9 +/- 0.7; normotensive, 3.1 +/- 0.1; P < 0.05), which exhibited apparent remodelling accompanied by a significant decrease in the density of connexin-43-positive gap junctions. Moreover, low-K(+)-related myocardial changes, including local impairment of intermyocyte junctions, ultrastructural alterations due to Ca(2+) overload and intercellular uncoupling, and decreased enzyme activities were more pronounced and more dispersed in hypertensive than normotensive rats. In conclusion, nitric oxide-deficient hypertension is associated with decreased myocardial coupling at gap junctions. The further localised deterioration of junctional coupling, due to low-K(+)-induced Ca(2+) disturbances, as well as spatial heterogeneity of myocardial alterations including interstitial fibrosis, probably provide the mechanisms for re-entry and sustaining ventricular fibrillation.

[Experimental studies for the hygienic standardization of Lasso in water]

Experimental hygienic-toxical study was carried out on amide herbicide lasso, aiming at its hygienic standardization in water. The studies were carried out in three aspects for the determination of its effect upon the organoleptic qualities of water, on the sanitary regime of water-reservoirs and toxic effect on organism. Threshold and subthershold concentrations of the deleterious effect on colour, small and taste of water were determined as well as on B0N5, on sanitary-indication microflora and on cold blooded organisms. The toxicological parameters for acute, subacute and chronic oral toxicity on albino rats were established. On the base of the experimental studies, differentiated hygienic norms (MAC) of lasso were elaborated in the three categories water-reservoirs - I mg/1 for I category and 5 mg/1 for II and II category.