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G-protein coupled receptors (GPCRs) are encoded by nonabundant mRNAs, and it is difficult to detect them reliably with the highly parallel methods that are in general use. Because of this, we developed and validated a sensitive, specific, semi-quantitative method for detecting these transcripts. We have used the method to profile GPCR transcripts in white blood cells (WBCs)–B, CD4, CD8, NK, and dendritic cells; monocytes, and macrophage-like monocytes treated with granulocyte-macrophage colony-stimulating factor–as well as platelets. On average, the white cells studied expressed 160 receptor mRNAs (range, 123–206). Platelets made 69. Some, but far from all, of the receptors we found have been detected earlier. We believe our data should stimulate studies of receptor function and contribute to drug development. [ABSTRACT FROM AUTHOR]

The Bundesbank's balance sheet and those of other central banks in the eurozone are currently showing high "operating" losses due to the discrepancy between the low interest bearing securities holdings from bond purchases and the now higher interest bearing commercial bank deposits. However, the current accounting practice does not reflect the associated losses in value anywhere near the market level – even though, according to the PSPP ruling of the German Federal Constitutional Court, the sale of securities before final maturity should be the rule. Even under the current valuation practice, an equity gap cannot be ruled out in the future, which is generally seen as unproblematic for central banks. However, there are risks in the context of recapitalisation by the state. Within the eurozone, national and European requirements could make such capital injections necessary. [ABSTRACT FROM AUTHOR]

Aims Human induced pluripotent stem cell–derived atrial cardiomyocytes (hiPSC-aCM) could be a helpful tool to study the physiology and diseases of the human atrium. To fulfil this expectation, the electrophysiology of hiPSC-aCM should closely resemble the situation in the human atrium. Data on the contribution of the slowly activating delayed rectifier currents (I Ks) to repolarization are lacking for both human atrium and hiPSC-aCM. Methods and results Human atrial tissues were obtained from patients with sinus rhythm (SR) or atrial fibrillation (AF). Currents were measured in human atrial cardiomyocytes (aCM) and compared with hiPSC-aCM and used to model I Ks contribution to action potential (AP) shape. Action potential was recorded by sharp microelectrodes. HMR-1556 (1 µM) was used to identify I Ks and to estimate I Ks contribution to repolarization. Less than 50% of hiPSC-aCM and aCM possessed I Ks. Frequency of occurrence, current densities, activation/deactivation kinetics, and voltage dependency of I Ks did not differ significantly between hiPSC-aCM and aCM, neither in SR nor AF. β-Adrenoceptor stimulation with isoprenaline did not increase I Ks neither in aCM nor in hiPSC-aCM. In tissue from SR, block of I Ks with HMR-1556 did not lengthen the action potential duration, even when repolarization reserve was reduced by block of the ultra-rapid repolarizing current with 4-aminopyridine or the rapidly activating delayed rectifier potassium outward current with E-4031. Conclusion I Ks exists in hiPSC-aCM with biophysics not different from aCM. As in adult human atrium (SR and AF), I Ks does not appear to relevantly contribute to repolarization in hiPSC-aCM. [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cells (hiPSCs) are an invaluable tool to study molecular mechanisms on a human background. Culturing stem cells at an oxygen level different from their microenvironmental niche impacts their viability. To understand this mechanistically, dermal skin fibroblasts of 52 probands were reprogrammed into hiPSCs, followed by either hyperoxic (20 % O 2 ) or physioxic (5 % O 2 ) culture and proteomic profiling. Analysis of chromosomal stability by Giemsa-banding revealed that physioxic -cultured hiPSC clones exhibited less pathological karyotypes than hyperoxic (e.g. 6 % vs. 32 % mosaicism), higher pluripotency as evidenced by higher Stage-Specific Embryonic Antigen 3 positivity, higher glucose consumption and lactate production. Global proteomic analysis demonstrated lower abundance of several subunits of NADH:ubiquinone oxidoreductase (complex I) and an underrepresentation of pathways linked to oxidative phosphorylation and cellular senescence. Accordingly, release of the pro-senescent factor IGFBP3 and β-galactosidase staining were lower in physioxic hiPSCs. RNA- and ATAC-seq profiling revealed a distinct hypoxic transcription factor-binding footprint, amongst others higher expression of the HIF1α-regulated target NDUFA4L2 along with increased chromatin accessibility of the NDUFA4L2 gene locus. While mitochondrial DNA content did not differ between groups, physioxic hiPSCs revealed lower polarized mitochondrial membrane potential, altered mitochondrial network appearance and reduced basal respiration and electron transfer capacity. Blue-native polyacrylamide gel electrophoresis coupled to mass spectrometry of the mitochondrial complexes detected higher abundance of NDUFA4L2 and ATP5IF1 and loss of incorporation into complex IV or V, respectively. Taken together, physioxic culture of hiPSCs improved chromosomal stability, which was associated with downregulation of oxidative phosphorylation and senescence and extensive re-wiring of mitochondrial complex composition., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: TE is a shareholder and a member of the scientific advisory board of DiNAQOR, which is not relating to this manuscript. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Aims: Human induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCM) could be a helpful tool to study the physiology and diseases of the human atrium. To fulfil this expectation, the electrophysiology of hiPSC-aCM should closely resemble the situation in the human atrium. Data on the contribution of the slowly activating delayed rectifier currents (IKs) to repolarization are lacking for both human atrium and hiPSC-aCM., Methods and Results: Human atrial tissues were obtained from patients with sinus rhythm (SR) or atrial fibrillation (AF). Currents were measured in human atrial cardiomyocytes (aCM) and compared with hiPSC-aCM and used to model IKs contribution to action potential (AP) shape. Action potential was recorded by sharp microelectrodes. HMR-1556 (1 µM) was used to identify IKs and to estimate IKs contribution to repolarization. Less than 50% of hiPSC-aCM and aCM possessed IKs. Frequency of occurrence, current densities, activation/deactivation kinetics, and voltage dependency of IKs did not differ significantly between hiPSC-aCM and aCM, neither in SR nor AF. β-Adrenoceptor stimulation with isoprenaline did not increase IKs neither in aCM nor in hiPSC-aCM. In tissue from SR, block of IKs with HMR-1556 did not lengthen the action potential duration, even when repolarization reserve was reduced by block of the ultra-rapid repolarizing current with 4-aminopyridine or the rapidly activating delayed rectifier potassium outward current with E-4031., Conclusion: I Ks exists in hiPSC-aCM with biophysics not different from aCM. As in adult human atrium (SR and AF), IKs does not appear to relevantly contribute to repolarization in hiPSC-aCM., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)