Dichotomous Impact of Myc on rRNA Gene Activation and Silencing in B Cell Lymphomagenesis

A major transcriptional output of cells is ribosomal RNA (rRNA), synthesized by RNA polymerase I (Pol I) from multicopy rRNA genes (rDNA). Constitutive silencing of an rDNA fraction by promoter CpG methylation contributes to the stabilization of these otherwise highly active loci. In cancers driven by the oncoprotein Myc, excessive Myc directly stimulates rDNA transcription. However, it is not clear when during carcinogenesis this mechanism emerges, and how Myc-driven rDNA activation affects epigenetic silencing. Here, we have used the Eµ-Myc mouse model to investigate rDNA transcription and epigenetic regulation in Myc-driven B cell lymphomagenesis. We have developed a refined cytometric strategy to isolate B cells from the tumor initiation, promotion, and progression phases, and found a substantial increase of both Myc and rRNA gene expression only in established lymphoma. Surprisingly, promoter CpG methylation and the machinery for rDNA silencing were also strongly up-regulated in the tumor progression state. The data indicate a dichotomous role of oncogenic Myc in rDNA regulation, boosting transcription as well as reinforcing repression of silent repeats, which may provide a novel angle on perturbing Myc function in cancer cells

Effect of Caffeine and Other Methylxanthines on Aβ-Homeostasis in SH-SY5Y Cells

Methylxanthines (MTX) are alkaloids derived from the purine-base xanthine. Whereas especially caffeine, the most prominent known MTX, has been formerly assessed to be detrimental, this point of view has changed substantially. MTXs are discussed to have beneficial properties in neurodegenerative diseases, however, the mechanisms of action are not completely understood. Here we investigate the effect of the naturally occurring caffeine, theobromine and theophylline and the synthetic propentofylline and pentoxifylline on processes involved in Alzheimer’s disease (AD). All MTXs decreased amyloid-β (Aβ) level by shifting the amyloid precursor protein (APP) processing from the Aβ-producing amyloidogenic to the non-amyloidogenic pathway. The α-secretase activity was elevated whereas β-secretase activity was decreased. Breaking down the molecular mechanism, caffeine increased protein stability of the major α-secretase ADAM10, downregulated BACE1 expression and directly decreased β-secretase activity. Additionally, APP expression was reduced. In line with literature, MTXs reduced oxidative stress, decreased cholesterol and a decreased in Aβ1-42 aggregation. In conclusion, all MTXs act via the pleiotropic mechanism resulting in decreased Aβ and show beneficial properties with respect to AD in neuroblastoma cells. However, the observed effect strength was moderate, suggesting that MTXs should be integrated in a healthy diet rather than be used exclusively to treat or prevent AD

The impact of tricuspid annular geometry on outcome after percutaneous edge-to-edge repair for severe tricuspid regurgitation

Background: Percutaneous tricuspid repair using the edge-to-edge technique is a novel treatment option. More data are needed to better understand which aspects predict a favorable outcome. Methods: Twenty high-risk patients (78.6 ± 8.3 years, EuroScore II 9.1 ± 7.7%, STS score 8.8 ± 4.3) with severe symptomatic tricuspid regurgitation (TR) were treated with the MitraClip® system. All patients underwent standardized pre-, peri-, and post-procedural evaluation. Acute success was defined as successful edge-to-edge repair with TR reduction of ≥ 1 grade and survival until hospital discharge.Results: Fifteen (75%) patients showed acute success until discharge and 12 (60%) at 30-day followup. In 5 (25%) patients repair failed due to either unsuccessful clip implantation (n = 2), single leaflet device attachment (n = 1), TR reduction < 1 grade (n = 1), or in-hospital death (n = 1). Comparing patients with successful procedure versus those with failed repair revealed similar comorbidities but more severe right heart failure, lower left ventricular ejection fraction, worse renal function, and higher diuretic equivalent doses in the failed repair group. No differences in conventional echocardiographic parameters for TR severity but more dilated tricuspid annulus geometry (tricuspid valve annulus, coaptation depth, tenting area) in the failed repair group were observed. The success rate of non-central/non-anteroseptal jet location was only 25%.Conclusions: Tricuspid annulus geometry assessment may be of crucial importance and seems to impact procedural outcomes in patients undergoing edge-to-edge tricuspid valve repair. Further investigations including advanced imaging are needed to better understand and treat this complex valve disease

Methylxanthines Induce a Change in the AD/Neurodegeneration-Linked Lipid Profile in Neuroblastoma Cells

Alzheimer’s disease (AD) is characterized by an increased plaque burden and tangle accumulation in the brain accompanied by extensive lipid alterations. Methylxanthines (MTXs) are alkaloids frequently consumed by dietary intake known to interfere with the molecular mechanisms leading to AD. Besides the fact that MTX consumption is associated with changes in triglycerides and cholesterol in serum and liver, little is known about the effect of MTXs on other lipid classes, which raises the question of whether MTX can alter lipids in a way that may be relevant in AD. Here we have analyzed naturally occurring MTXs caffeine, theobromine, theophylline, and the synthetic MTXs pentoxifylline and propentofylline also used as drugs in different neuroblastoma cell lines. Our results show that lipid alterations are not limited to triglycerides and cholesterol in the liver and serum, but also include changes in sphingomyelins, ceramides, phosphatidylcholine, and plasmalogens in neuroblastoma cells. These changes comprise alterations known to be beneficial, but also adverse effects regarding AD were observed. Our results give an additional perspective of the complex link between MTX and AD, and suggest combining MTX with a lipid-altering diet compensating the adverse effects of MTX rather than using MTX alone to prevent or treat AD

Targeted Lipidomics of Mitochondria in a Cellular Alzheimer’s Disease Model

Alzheimer’s disease (AD) is neuropathologically characterized by the accumulation of Amyloid-β (Aβ) in senile plaques derived from amyloidogenic processing of a precursor protein (APP). Recently, changes in mitochondrial function have become in the focus of the disease. Whereas a link between AD and lipid-homeostasis exists, little is known about potential alterations in the lipid composition of mitochondria. Here, we investigate potential changes in the main mitochondrial phospholipid classes phosphatidylcholine, phosphatidylethanolamine and the corresponding plasmalogens and lyso-phospholipids of a cellular AD-model (SH-SY5Y APPswedish transfected cells), comparing these results with changes in cell-homogenates. Targeted shotgun-lipidomics revealed lipid alterations to be specific for mitochondria and cannot be predicted from total cell analysis. In particular, lipids containing three and four times unsaturated fatty acids (FA X:4), such as arachidonic-acid, are increased, whereas FA X:6 or X:5, such as eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), are decreased. Additionally, PE plasmalogens are increased in contrast to homogenates. Results were confirmed in another cellular AD model, having a lower affinity to amyloidogenic APP processing. Besides several similarities, differences in particular in PE species exist, demonstrating that differences in APP processing might lead to specific changes in lipid homeostasis in mitochondria. Importantly, the observed lipid alterations are accompanied by changes in the carnitine carrier system, also suggesting an altered mitochondrial functionalit

Rationale and Design of JenaMACS—Acute Hemodynamic Impact of Ventricular Unloading Using the Impella CP Assist Device in Patients with Cardiogenic Shock

Introduction: Cardiogenic shock due to myocardial infarction or heart failure entails a reduction in end organ perfusion. Patients who cannot be stabilized with inotropes and who experience increasing circulatory failure are in need of an extracorporeal mechanical support system. Today, small, percutaneously implantable cardiac assist devices are available and might be a solution to reduce mortality and complications. A temporary, ventricular, continuous flow propeller pump using magnetic levitation (Impella ® ) has been approved for that purpose. Methods and Study Design: JenaMACS (Jena Mechanical Assist Circulatory Support) is a monocenter, proof-of-concept study to determine whether treatment with an Impella CP ® leads to improvement of hemodynamic parameters in patients with cardiogenic shock requiring extracorporeal, hemodynamic support. The primary outcomes of JenaMACS are changes in hemodynamic parameters measured by pulmonary artery catheterization and changes in echocardiographic parameters of left and right heart function before and after Impella ® implantation at different support levels after 24 h of support. Secondary outcome measures are hemodynamic and echocardiographic changes over time as well as clinical endpoints such as mortality or time to hemodynamic stabilization. Further, laboratory and clinical safety endpoints including severe bleeding, stroke, neurological outcome, peripheral ischemic complications and occurrence of sepsis will be assessed. JenaMACS addresses essential questions of extracorporeal, mechanical, cardiac support with an Impella CP ® device in patients with cardiogenic shock. Knowledge of the acute and subacute hemodynamic and echocardiographic effects may help to optimize therapy and improve the outcome in those patients. Conclusion: The JenaMACS study will address essential questions of extracorporeal, mechanical, cardiac support with an Impella CP ® assist device in patients with cardiogenic shock. Knowledge of the acute and subacute hemodynamic and echocardiographic effects may help to optimize therapy and may improve outcome in those patients. Ethics and Dissemination: The protocol was approved by the institutional review board and ethics committee of the University Hospital of Jena. Written informed consent will be obtained from all participants of the study. The results of this study will be published in a renowned international medical journal, irrespective of the outcomes of the study. Strengths and Limitations: JenaMACS is an innovative approach to characterize the effect of additional left ventricular mechanical unloading during cardiogenic shock via a minimally invasive cardiac assist system (Impella CP ® ) 24 h after onset and will provide valuable data for acute interventional strategies or future prospective trials. However, JenaMACS, due to its proof-of-concept design, is limited by its single center protocol, with a small sample size and without a comparison group

Peripheral T Cell Cytokine Responses for Diagnosis of Active Tuberculosis

BACKGROUND: A test for diagnosis of active Tuberculosis (TB) from peripheral blood could tremendously improve clinical management of patients. METHODS: Of 178 prospectively enrolled patients with possible TB, 60 patients were diagnosed with pulmonary and 27 patients with extrapulmonary TB. The frequencies of Mycobacterium tuberculosis (MTB) specific CD4(+) T cells and CD8(+) T cells producing cytokines were assessed using overnight stimulation with purified protein derivate (PPD) or early secretory antigenic target (ESAT)-6, respectively. RESULTS: Among patients with active TB, an increased type 1 cytokine profile consisting of mainly CD4(+) T cell derived interferon (IFN)-γ was detectable. Despite contributing to the cytokine profile as a whole, the independent diagnostic performance of one cytokine producing T cells as well as polyfunctional T cells was poor. IFN-γ/Interleukin(IL)-2 cytokine ratios discriminated best between active TB and other diseases. CONCLUSION: T cells producing one cytokine and polyfunctional T cells have a limited role in diagnosis of active TB. The significant shift from a "memory type" to an "effector type" cytokine profile may be useful for further development of a rapid immune-diagnostic tool for active TB

Towards a concentration closure of sub-6 nm aerosol particles and sub-3 nm atmospheric clusters

Atmospheric clusters play a key role in atmospheric new particle formation and they are a sensitive indicator for atmospheric chemistry. Both the formation and loss of atmospheric clusters include a complex set of interlinked physical and chemical processes, and therefore their dynamics is highly non-linear. Here we derive a set of simple equations to estimate the atmospheric cluster concentrations in size ranges of 1.5–2 nm and 2–3 nm as well as 3–6 nm aerosol particles. We compared the estimated concentrations with measured ones both in a boreal forest site (the SMEAR II station in Hyytiälä, Finland) and in an urban site (the AHL/BUCT station in Beijing, China). We made this comparison first for 3–6 nm particles, since in this size range observations are more reliable than at smaller sizes, and then repeated it for the 2–3 nm size range. Finally, we estimated cluster concentrations in the 1.5–2 nm size range. Our main finding is that the present observations are able to detect a major fraction of existing atmospheric clusters.Atmospheric clusters play a key role in atmospheric new particle formation and they are a sensitive indicator for atmospheric chemistry. Both the formation and loss of atmospheric clusters include a complex set of interlinked physical and chemical processes, and therefore their dynamics is highly non-linear. Here we derive a set of simple equations to estimate the atmospheric cluster concentrations in size ranges of 1.5–2 nm and 2–3 nm as well as 3–6 nm aerosol particles. We compared the estimated concentrations with measured ones both in a boreal forest site (the SMEAR II station in Hyytiälä, Finland) and in an urban site (the AHL/BUCT station in Beijing, China). We made this comparison first for 3–6 nm particles, since in this size range observations are more reliable than at smaller sizes, and then repeated it for the 2–3 nm size range. Finally, we estimated cluster concentrations in the 1.5–2 nm size range. Our main finding is that the present observations are able to detect a major fraction of existing atmospheric clusters.Peer reviewe