Serum microRNA in patients undergoing atrial fibrillation ablation

MicroRNAs mediate posttranscriptional gene regulation. The aim of the study was to find a microRNA predictor of successful atrial fibrillation (AF) ablation. A total of 109 patients undergoing first-time AF ablation were included. Nineteen patients were selected to undergo serum microRNA sequencing (study group). The sequencing data were used to select several microRNAs that correlated with 12-month recurrences after AF ablation. Those microRNAs were validated by digital droplet PCR in samples from remaining 90 patients. All patients underwent pulmonary vein isolation (RF ablation, contact force catheter, electroanatomical system). The endpoint of the study was the 12-month AF recurrence rate; the overall recurrence rate was 42.5%. In total, levels of 34 miRNAs were significantly different in sera from patients with AF recurrence compared to patients without AF recurrence. Six microRNAs (miR-183-5p, miR-182-5p, miR-32-5p, miR-107, miR-574-3p, and miR-144-3p) were validated in the whole group. Data from the validation group did not confirm the observations from the study group, as no significant differences were found between miRNAs serum levels in patients with and without recurrences 12 months after AF ablation.

Circulating miR-30a-5p as a prognostic biomarker of left ventricular dysfunction after acute myocardial infarction

Left ventricular (LV) dysfunction after acute myocardial infarction (AMI) is associated with an increased risk of heart failure (HF) development. Diverse microRNAs (miRNAs) have been shown to appear in the bloodstream following various cardiovascular events. The aim of this study was to identify prognostic miRNAs associated with LV dysfunction following AMI. Patients were divided into subgroups comprising patients who developed or not LV dysfunction within six months of the infarction. miRNA profiles were determined in plasma and serum samples of the patients on the first day of AMI. Levels of 14 plasma miRNAs and 16 serum miRNAs were significantly different in samples from AMI patients who later developed LV dysfunction compared to those who did not. Two miRNAs were up-regulated in both types of material. Validation in an independent group of patients, using droplet digital PCR (ddPCR) confirmed that miR-30a-5p was significantly elevated on admission in those patients who developed LV dysfunction and HF symptoms six months after AMI. A bioinformatics analysis indicated that miR-30a-5p may regulate genes involved in cardiovascular pathogenesis. This study demonstrates, for the first time, a prognostic value of circulating miR-30a-5p and its association with LV dysfunction and symptoms of HF after AMI.

miR-22-5p revealed as a potential biomarker involved in the acute phase of myocardial infarction via profiling of circulating microRNAs

Acute myocardial infarction (AMI) is a life-threatening episode of coronary artery disease. Recently, circulating myocardial-derived microRNAs (miRNAs) have been reported as potential biomarkers of infarction. The present study aimed to identify differentially expressed miRNAs in patients with ST-segment elevation myocardial infarction that could be potentially dysregulated in response to early myocardial damage. miRNA expression profile analysis was performed using the Serum/Plasma Focus miRNA Polymerase Chain Reaction (PCR) panel of Exiqon A/S (Vedbaek, Denmark) on plasma samples of patients on the first day of AMI (admission) and on samples from the identical patients collected six months following AMI. Selected miRNAs were validated by reverse transcription‑quantitative PCR (RT‑qPCR) using independent patients with AMI and a control group of patients with a stable coronary artery disease. Thirty‑two species of plasma miRNA were differentially expressed (P<0.05) on admission compared with six months following AMI. Subsequent validation in an independent patient group confirmed that miR‑133b and miR‑22‑5p were significantly up‑regulated in the serum of patients with AMI. The receiver operating characteristic (ROC) curve analysis demonstrated a diagnostic utility for miR-22-5p, which has not previously been reported to be associated with AMI. Among the selected miRNAs, miR‑22‑5p represents a novel promising biomarker for the diagnosis of AMI.

Genetic engineering and molecular characterization of yeast strain expressing hybrid human-yeast squalene synthase as a tool for anti-cholesterol drug assessment

AIMS

The main objective of the study is molecular and biological characterization of the human-yeast hybrid squalene synthase (SQS), as a promising target for treatment of hypercholesterolaemia.

METHODS AND RESULTS

The human-yeast hybrid SQS, with 67% amino acids, including the catalytic site derived from human enzyme, was expressed in Saccharomyces cerevisiae strain deleted of its own SQS gene. The constructed strain has a decreased level of sterols compared to the control strain. The mevalonate pathway and sterol biosynthesis genes are induced and the level of triacylglycerols is increased. Treatment of the strain with rosuvastatin or zaragozic acid, two mevalonate pathway inhibitors, decreased the amounts of squalene, lanosterol and ergosterol, and up-regulated expression of several genes encoding enzymes responsible for biosynthesis of ergosterol precursors. Conversely, expression of the majority genes implicated in the biosynthesis of other mevalonate pathway end products, ubiquinone and dolichol, was down-regulated.

CONCLUSIONS

The S. cerevisiae strain constructed in this study enables to investigate the physiological and molecular effects of inhibitors on cell functioning.

SIGNIFICANCE AND IMPACT OF THE STUDY

The yeast strain expressing hybrid SQS with the catalytic core of human enzyme is a convenient tool for efficient screening for novel inhibitors of cholesterol-lowering properties.

Interindividual variability of atorvastatin treatment influence on the MPO gene expression in patients after acute myocardial infarction

Myeloperoxidase (MPO) and C-reactive protein (CRP) may play critical roles in generation of oxidative stress and the development of the systemic inflammatory response. The aim of the study was to determine the effect of atorvastatin therapy on the MPO gene expression and its plasma level in relation to lipids level lowering and an anti-inflammatory response in patients after acute myocardial infarction. The research material was represented by 112 samples. Thirty-eight patients with first AMI receiving atorvastatin therapy (40 mg/day) and followed up for one month were involved in the study. The relative MPO gene expression in peripheral blood mononuclear cells (PBMCs) was examined using RT-qPCR in 38 patients before-, 38 patients after-therapy and in 36 patients as the control group. The plasma concentrations of MPO and serum concentrations of biochemical parameters were determined using commercially available diagnostic tests. After one month of atorvastatin therapy, in 60.5% patients a decrease of MPO gene expression, whereas in 39.5% patients an increase, was observed. The plasma MPO levels behaved in the same way as the MPO gene expression. However, the serum lipids and CRP concentrations were significantly lower after one month of atorvastatin therapy in both groups of patients - with decreased and increased MPO gene expression. Atorvastatin exhibited a different effect on MPO gene expression and its plasma level. Short-term atorvastatin therapy resulted in lipid lowering and anti-inflammatory activity in patients after AMI, independently of its effect on MPO gene expression. The molecular mechanisms of this phenomenon are not yet defined and require further research.

The rs12526453 Polymorphism in an Intron of the PHACTR1 Gene and Its Association with 5-Year Mortality of Patients with Myocardial Infarction

Objective

The rs12526453 (C/G) is a single nucleotide polymorphism in an intron of the PHACTR1 gene (phosphatase and actin regulator 1). The C allele is associated with increased risk of coronary artery disease in an unknown mechanism. We investigated its association with long-term overall mortality in patients with ST-elevation myocardial infarction (STEMI) treated invasively.

Methods

Two independent groups of patients with STEMI were analyzed: a derivation group (n= 638) and a validation one (n=348). Genotyping was performed with the TaqMan method. The analyzed end-point was total long term mortality. Additionally, transcriptomic analysis was performed in mononuclear blood leukocytes from rs12526453 CC monozygotes or G allele carriers.

Results

In the study group (mean age 62.3 ± 11.9 years; 24.9% of females, n=159), percentages of CC, CG, and GG genotypes were 45.3% (n=289), 44.7% (n=285), and 10% (n=64), respectively. In the 5-year follow-up 105 patients died (16.46%). CC homozygotes had significantly lower mortality compared to other genotypes: 13.1% (n=38) vs. 18.3% in G-allele carriers (n=67), (p=0.017, Cox`s F test). In the validation group 47 patients died within 3 years (13.5%). We confirmed lower mortality of CC homozygotes: 10.1 % (n=18) vs. 16.95% in G-allele carriers (n=29), (p=0.031, Cox`s F test). Transcriptomic analysis revealed a markedly higher expression of NLRP-2 in CC homozygotes.

Conclusions

The rs12526453 CC homozygotes (previously associated with increased risk of myocardial infarction) showed, in 2 independent samples, better long-term survival. The finding of such high effect size, after appropriate validation, could potentially be translated into clinical practice.

Gene expression profiling reveals potential prognostic biomarkers associated with the progression of heart failure

Background

Heart failure (HF) is the most common cause of morbidity and mortality in developed countries. Here, we identify biologically relevant transcripts that are significantly altered in the early phase of myocardial infarction and are associated with the development of post-myocardial infarction HF.

Methods

We collected peripheral blood samples from patients with ST-segment elevation myocardial infarction (STEMI): n = 111 and n = 41 patients from the study and validation groups, respectively. Control groups comprised patients with a stable coronary artery disease and without a history of myocardial infarction. Based on plasma NT-proBNP level and left ventricular ejection fraction parameters the STEMI patients were divided into HF and non-HF groups. Microarrays were used to analyze mRNA levels in peripheral blood mononuclear cells (PBMCs) isolated from the study group at four time points and control group. Microarray results were validated by RT-qPCR using whole blood RNA from the validation group.

Results

Samples from the first three time points (admission, discharge, and 1 month after AMI) were compared with the samples from the same patients collected 6 months after AMI (stable phase) and with the control group. The greatest differences in transcriptional profiles were observed on admission and they gradually stabilized during the follow-up. We have also identified a set of genes the expression of which on the first day of STEMI differed significantly between patients who developed HF after 6 months of observation and those who did not. RNASE1, FMN1, and JDP2 were selected for further analysis and their early up-regulation was confirmed in HF patients from both the study and validation groups. Significant correlations were found between expression levels of these biomarkers and clinical parameters. The receiver operating characteristic (ROC) curves indicated a good prognostic value of the genes chosen.

Conclusions

This study demonstrates an altered gene expression profile in PBMCs during acute myocardial infarction and through the follow-up. The identified gene expression changes at the early phase of STEMI that differentiated the patients who developed HF from those who did not could serve as a convenient tool contributing to the prognosis of heart failure.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-015-0149-z) contains supplementary material, which is available to authorized users.

The effects of statins on the mevalonic acid pathway in recombinant yeast strains expressing human HMG-CoA reductase

Background

The yeast Saccharomyces cerevisiae can be a useful model for studying cellular mechanisms related to sterol synthesis in humans due to the high similarity of the mevalonate pathway between these organisms. This metabolic pathway plays a key role in multiple cellular processes by synthesizing sterol and nonsterol isoprenoids. Statins are well-known inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the key enzyme of the cholesterol synthesis pathway. However, the effects of statins extend beyond their cholesterol-lowering action, since inhibition of HMGR decreases the synthesis of all products downstream in the mevalonate pathway. Using transgenic yeast expressing human HMGR or either yeast HMGR isoenzyme we studied the effects of simvastatin, atorvastatin, fluvastatin and rosuvastatin on the cell metabolism.

Results

Statins decreased sterol pools, prominently reducing sterol precursors content while only moderately lowering ergosterol level. Expression of genes encoding enzymes involved in sterol biosynthesis was induced, while genes from nonsterol isoprenoid pathways, such as coenzyme Q and dolichol biosynthesis or protein prenylation, were diversely affected by statin treatment. Statins increased the level of human HMGR protein substantially and only slightly affected the levels of Rer2 and Coq3 proteins involved in non-sterol isoprenoid biosynthesis.

Conclusion

Statins influence the sterol pool, gene expression and protein levels of enzymes from the sterol and nonsterol isoprenoid biosynthesis branches and this effect depends on the type of statin administered. Our model system is a cheap and convenient tool for characterizing individual statins or screening for novel ones, and could also be helpful in individualized selection of the most efficient HMGR inhibitors leading to the best response and minimizing serious side effects.

[Evaluation of the usefulness of vitamin/mineral preparations as dietary supplements]

The purpose of this work was to evaluate the vitamin/mineral preparations available on Polish market in 1995 in relation to their usefulness as dietary supplements. On the basic of the information in compendia, scientific papers, booklets, leaflets etc. the catalog of products containing vitamins and/or minerals was prepared. Complete data on composition, designation and other descriptors of 274 products were included. For further 28 preparations no full data were available. More than 53% of preparations were produced in Poland. Out of 274 preparations, 50% contained a single nutrient, while 20.1% contained 2-5 nutrients, 14.6%--from 6 to 10 nutrients, 13.1%--from 11 to 20 and only 2%--from 21 to 30 nutrients. Most of the products were intended for adults (165 preparations), adolescents (154 preparations) and children (132 preparations). Only 16 products were designed for pregnant and lactating women. Some of the preparations were intended for more than one population group with different dosage recommended by the producer. The amounts of nutrients in a single unit (pill, tablet etc.) of each product as well as percentage of recommended daily intake were estimated. Generally, these amounts were higher in products containing single nutrient than in multivitamin/mineral preparations. Out of 274 products included into the catalog, 132 met criteria established for dietary supplements in Poland (i.e. the amount of nutrients in supplements should not exceed 150% RDA). Among them in 25 preparations the amounts of nutrients in a unit of product were in agreement with a definition of supplements but daily doses recommended by the producers were much higher than 150% of RDA. For 33 products the amounts of nutrients in single units were very low, therefore to obtain a dose significant for dietary supplementation, one should take several units per day, usually the maximal dose recommended by producer. For 74 preparations the amounts of nutrients in single units as well as in daily doses recommended by the producer met criteria for supplements. Lack of complete and clear information on the label of vitamin/mineral preparations as well as lack of data on percentage of RDA covered by nutrients in the unit of product are the most important difficulties in choosing for dietary supplementation. The knowledge of composition of preparations containing various nutrients is necessary for nutritionist who want to assess the intake and nutritional status of some individuals as well as for their counselling work.

[Cyst of cisterna ambiens: case report]

The authors describe a rare case of congenital cyst of cisterna ambiens treated surgically. Histological examination of cyst wall suggested that the cyst belonged to the group of developmental anomalies of the type of dysraphic intracranial cerebral herniae.