257 research outputs found

    Genome maintenance functions of a putative Trypanosoma brucei translesion DNA polymerase include telomere association and a role in antigenic variation

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    Maintenance of genome integrity is critical to guarantee transfer of an intact genome from parent to off-spring during cell division. DNA polymerases (Pols) provide roles in both replication of the genome and the repair of a wide range of lesions. Amongst replicative DNA Pols, translesion DNA Pols play a particular role: replication to bypass DNA damage. All cells express a range of translesion Pols, but little work has examined their function in parasites, including whether the enzymes might contribute to host-parasite interactions. Here, we describe a dual function of one putative translesion Pol in African trypanosomes, which we now name TbPolIE. Previously, we demonstrated that TbPolIE is associated with telomeric sequences and here we show that RNAi-mediated depletion of TbPolIE transcripts results in slowed growth, altered DNA content, changes in cell morphology, and increased sensitivity to DNA damaging agents. We also show that TbPolIE displays pronounced localization at the nuclear periphery, and that its depletion leads to chromosome segregation defects and increased levels of endogenous DNA damage. Finally, we demonstrate that TbPolIE depletion leads to deregulation of telomeric variant surface glycoprotein genes, linking the function of this putative translesion DNA polymerase to host immune evasion by antigenic variation

    Imaging Predictors of Left Ventricular Functional Recovery after Reperfusion Therapy of ST-Elevation Myocardial Infarction Assessed by Cardiac Magnetic Resonance

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    Background: Left ventricular global longitudinal strain (LV GLS) is a superior predictor of adverse cardiac events in patients with myocardial infarction and heart failure. We investigated the ability of morphological features of infarcted myocardium to detect acute left ventricular (LV) dysfunction and predict LV functional recovery after three months in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods: Sixty-six STEMI patients were included in the C-reactive protein (CRP) apheresis in Acute Myocardial Infarction Study (CAMI-1). LV ejection fraction (LVEF), LV GLS, LV global circumferential strain (LV GCS), infarct size (IS), area-at-risk (AAR), and myocardial salvage index (MSI) were assessed by CMR 5 ± 3 days (baseline) and 12 ± 2 weeks after (follow-up) the diagnosis of first acute STEMI. Results: Significant changes in myocardial injury parameters were identified after 12 weeks of STEMI diagnosis. IS decreased from 23.59 ± 11.69% at baseline to 18.29 ± 8.32% at follow-up (p < 0.001). AAR and MVO also significantly reduced after 12 weeks. At baseline, there were reasonably moderate correlations between IS and LVEF (r = −0.479, p < 0.001), LV GLS (r = 0.441, p < 0.001) and LV GCS (r = 0.396, p = 0.001) as well as between AAR and LVEF (r = −0.430, p = 0.003), LV GLS (r = 0.501, p < 0.001) and weak with LV GCS (r = 0.342, p = 0.020). At follow-up, only MSI and change in LV GCS over time showed a weak but significant correlation (r = −0.347, p = 0.021). Patients with larger AAR at baseline improved more in LVEF (p = 0.019) and LV GLS (p = 0.020) but not in LV GCS. Conclusion: The CMR tissue characteristics of myocardial injury correlate with the magnitude of LV dysfunction during the acute stage of STEMI. AAR predicts improvement in LVEF and LV GLS, while MSI is a sensitive marker of LV GCS recovery at three months follow-up after STEMI

    Direct Flow Medical vs. Edwards Sapien 3 Prosthesis: A Propensity Matched Comparison on Intermediate Safety and Mortality

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    Aims: To compare intermediate performance and mortality rates in patients, who underwent transcatheter aortic valve implantation (TAVI) with two different types of prostheses: Edwards Sapien 3 (ES3) and Direct Flow Medical (DFM).Methods and Results: 42 consecutive patients implanted with a DFM prosthesis for severe aortic stenosis were matched 1:1 with an equal number of patients, who received an ES3 during the same period. Primary endpoint was mortality. MACE, as a composite of all-cause death, stroke, and re-do-procedure (valve-in-valve), was defined as secondary endpoint. Moreover, we compared NYHA class, NT-proBNP-levels and the extent of restenosis. Patients were followed for 2 years. DFM patients showed echocardiographic elevated mean pressure gradients compared to ES3 patients before discharge (11.2 mmHg ± 5.3 vs. 3.5 mmHg ± 2.7; p &lt; 0.001) and upon 6-months follow-up (20.3 mmHg ± 8.8 vs. 12.3 mmHg ± 4.4; p &lt; 0.001). ES3 candidates showed superior NYHA class at follow-up (p = 0.001). Kaplan-Meier analysis revealed significantly worse survival in patients receiving a DFM prosthesis compared to ES3 (Breslow p = 0.020). MACE occurred more often in DFM patients compared to ES3 (Breslow p = 0.006).Conclusions: Patients receiving DFM valve prostheses showed worse survival and higher rates in MACE compared to ES3. Prosthesis performance regarding mean pressure gradients and patients' NYHA class also favored ES3

    PU.1 controls fibroblast polarization and tissue fibrosis

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    Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix, which induces scarring and organ failure. By contrast, a hallmark feature of fibroblasts in arthritis is degradation of the extracellular matrix because of the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms that drive these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts remain unknown. Here we identify the transcription factor PU.1 as an essential regulator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms that normally control the expression of PU.1 expression is perturbed in various fibrotic diseases, resulting in the upregulation of PU.1, induction of fibrosis-associated gene sets and a phenotypic switch in extracellular matrix-producing pro-fibrotic fibroblasts. By contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables reprogramming of fibrotic fibroblasts into resting fibroblasts, leading to regression of fibrosis in several organs

    Baroreflex Activation Therapy for the Treatment of Heart Failure With a Reduced Ejection Fraction

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    AbstractObjectivesThe objective of this clinical trial was to assess the safety and efficacy of carotid BAT in advanced HF.BackgroundIncreased sympathetic and decreased parasympathetic activity contribute to heart failure (HF) symptoms and disease progression. Baroreflex activation therapy (BAT) results in centrally mediated reduction of sympathetic outflow and increased parasympathetic activity.MethodsPatients with New York Heart Association (NYHA) functional class III HF and ejection fractions ≤35% on chronic stable guideline-directed medical therapy (GDMT) were enrolled at 45 centers in the United States, Canada, and Europe. They were randomly assigned to receive ongoing GDMT alone (control group) or ongoing GDMT plus BAT (treatment group) for 6 months. The primary safety end point was system- and procedure-related major adverse neurological and cardiovascular events. The primary efficacy end points were changes in NYHA functional class, quality-of-life score, and 6-minute hall walk distance.ResultsOne hundred forty-six patients were randomized, 70 to control and 76 to treatment. The major adverse neurological and cardiovascular event–free rate was 97.2% (lower 95% confidence bound 91.4%). Patients assigned to BAT, compared with control group patients, experienced improvements in the distance walked in 6 min (59.6 ± 14 m vs. 1.5 ± 13.2 m; p = 0.004), quality-of-life score (–17.4 ± 2.8 points vs. 2.1 ± 3.1 points; p < 0.001), and NYHA functional class ranking (p = 0.002 for change in distribution). BAT significantly reduced N-terminal pro–brain natriuretic peptide (p = 0.02) and was associated with a trend toward fewer days hospitalized for HF (p = 0.08).ConclusionsBAT is safe and improves functional status, quality of life, exercise capacity, N-terminal pro–brain natriuretic peptide, and possibly the burden of heart failure hospitalizations in patients with GDMT-treated NYHA functional class III HF. (Barostim Neo System in the Treatment of Heart Failure; NCT01471860; Barostim HOPE4HF [Hope for Heart Failure] Study; NCT01720160
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