Polymorphisms of the gene encoding apolipoprotein E have been implicated in the pathogenesis of peripheral and coronary artery disease and neurodegenerative disorders such as sporadic and late-onset familial forms of Alzheimer's disease. We have developed TaqMan assay systems for the single nucleotide polymorphisms -219G/T, located in the promoter of the apolipoprotein E gene, 113G/C, present in the transcriptional enhancer element of intron 1, 334T/C, determining Cys or Arg as amino acid residue 112 of mature apolipoprotein E, and 472C/T, determining Arg or Cys as residue 158. The accuracy of genotype determination with the TaqMan systems was demonstrated by analyses with restriction endonucleases. We determined the genotypes of the apolipoprotein E polymorphisms in 2349 study subjects. The genotypes were distributed as: -219GG = 27.3%, -219GT = 49.1%, and -219TT = 23.6% (p = 0.435); 113GG = 41.3%, 113GC = 45.2%, and 113CC = 13.5% (p = 0.343); 334TT = 73.4%, 334TC = 24.7%, and 334CC = 1.9% (p = 0.539); 472CC = 86.3%, 472CT=12.8%, and 472TT= 0.9% ( p = 0.004) (Hardy-Weinberg equilibrium estimates are given in parentheses). The allele combinations which define the three major isoforms of apolipoprotein E, namely apoE2, apoE3, and apoE4, had the following allele frequencies: 334T/472T (epsilon2; 112Cys/158Cys) = 7.3%, 334T/472C (epsilon3; 112Cys/158Arg) = 78.4%, and 334C/472C (epsilon4; 112Arg/158Arg) = 14.2%, respectively. ApoE genotypes were distributed as: epsilon2epsilon2 = 0.9%, epsilon2epsilon3 = 11.2%, epsilon2epsilon4 = 1.6%, epsilon3epsilon3 = 61.3%, epsilon3epsilon4 = 23.1%, and epsilon4epsilon4 = 1.9% (p = 0.014). The TaqMan assays allow for fast and sensitive genotyping and are especially suitable for studies including large numbers of participants.

The mechanisms underlying cardiac automaticity are still incompletely understood and controversial. Here we report the complete conditional and time-controlled silencing of the "funny" current (If) by expression of a dominant-negative, non-conductive HCN4-channel subunit (hHCN4-AYA). Heart-specific If silencing caused altered [Ca2+]i release and Ca2+ handling in the sinoatrial node, impaired pacemaker activity, and symptoms reminiscent of severe human disease of pacemaking. The effects of If silencing critically depended on the activity of the autonomic nervous system. We were able to rescue the failure of impulse generation and conduction by additional genetic deletion of cardiac muscarinic G-protein-activated (GIRK4) channels in If-deficient mice without impairing heartbeat regulation. Our study establishes the role of f-channels in cardiac automaticity and indicates that arrhythmia related to HCN loss-of-function may be managed by pharmacological or genetic inhibition of GIRK4 channels, thus offering a new therapeutic strategy for the treatment of heart rhythm diseases.

Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein–activated K+ current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4−/− mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4−/− mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4−/− animals. Although the relative extent of heart rate regulation of Girk4−/− mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological β-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4−/− animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct β-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation.

Rationale The transcription factor Islet-1 is a marker of cardiovascular progenitors during embryogenesis. The isolation of Islet-1-positive (Islet-1+) cells from early postnatal hearts suggested that Islet-1 also marks cardiac progenitors in adult life. Objective We investigated the distribution and identity of Islet-1+ cells in adult murine heart and evaluated whether their number or distribution change with age or after myocardial infarction. Methods and Results Distribution of Islet-1+ cells in adult heart was investigated using gene targeted mice with nuclear β-galactosidase inserted into the Islet-1 locus. nLacZ-positive cells were only present in 3 regions of the adult heart: clusters in the interatrial septum and around the pulmonary veins, scattered within the wall of the great vessels, and a strictly delimited cluster between the right atrium and superior vena cava. Islet-1+ cells in the first type of clusters coexpressed markers for parasympathetic neurons. Positive cells in the great arteries coexpressed smooth muscle actin and myosin heavy chain, indicating a smooth muscle cell identity. Very few Islet-1+ cells within the outflow tract expressed the cardiomyocyte marker α-actinin. Islet-1+ cells in the right atrium coexpressed the sinoatrial node pacemaker cell marker HCN4. Cell number and localization remained unchanged between 1 to 18 months of age. Consistently Islet-1 mRNA was detected in human sinoatrial node. Islet-1+ cells could not be detected in the infarct zone 2 to 28 days after myocardial infarction, aside from 10 questionable cells in 1/13 hearts. Conclusions Our results identify Islet-1 as a novel marker of the adult sinoatrial node and do not provide evidence for Islet-1+ cells to serve as cardiac progenitors.

Background Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), an emerging virus, has caused a global pandemic. Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has led to high hospitalization rates worldwide. Little is known about the occurrence of in-hospital cardiac arrest (IHCA) and high mortality rates have been proposed. The aim of this study was to investigate the incidence, characteristics and outcome of IHCA during the pandemic in comparison to an earlier period. Methods This was a retrospective analysis of data prospectively recorded during 3-month-periods 2019 and 2020 at the University Medical Centre Hamburg-Eppendorf (Germany). All consecutive adult patients with IHCA were included. Clinical parameters, neurological outcomes and organ failure/support were assessed. Results During the study period hospital admissions declined from 18,262 (2019) to 13,994 (2020) (− 23%). The IHCA incidence increased from 4.6 (2019: 84 IHCA cases) to 6.6 (2020: 93 IHCA cases)/1000 hospital admissions. Median stay before IHCA was 4 (1–9) days. Demographic characteristics were comparable in both periods. IHCA location shifted towards the ICU (56% vs 37%, p < 0.01); shockable rhythm (VT/VF) (18% vs 29%, p = 0.05) and defibrillation were more frequent in the pandemic period (20% vs 35%, p < 0.05). Resuscitation times, rates of ROSC and post-CA characteristics were comparable in both periods. The severity of illness (SAPS II/SOFA), frequency of mechanical ventilation and frequency of vasopressor therapy after IHCA were higher during the 2020 period. Overall, 43 patients (12 with & 31 without COVID-19), presented with respiratory failure at the time of IHCA. The Horowitz index and resuscitation time were significantly lower in patients with COVID-19 (each p < 0.01). Favourable outcomes were observed in 42 and 10% of patients with and without COVID-19-related respiratory failure, respectively. Conclusion Hospital admissions declined during the pandemic, but a higher incidence of IHCA was observed. IHCA in patients with COVID-19 was a common finding. Compared to patients with non-COVID-19-related respiratory failure, the outcome was improved.

In addition to senile plaques, neurofibrillary tangles are characteristic of Alzheimer's disease (AD) pathology, suggesting a clear involvement of the microtubule-associated protein tau (MAPT) in AD. Recent findings, suggesting that the H1c haplotype is associated with increased risk, now also implicate MAPT genetically. In this study, we aim to clarify this association by a fine mapping approach using both a traditional phenotypic association analysis and a quantitative trait (QT) analysis using cerebrospinal fluid (CSF) tau protein levels in the German population. Here, we report that both methodologies identify that the H1c haplotype may play important role in AD (AD risk, P = 0.007, uncorrected; CSF tau levels, P = 0.027, uncorrected). Further, the use of a sliding window approach in the QT analysis allowed for the narrowing down of the region where a probable causal variant may be located. The data suggest that this may lie at or within close proximity to the rs242557 single nucleotide polymorphism as association with CSF tau levels seems to be primarily driven by rs242557 in a gene dosagedependent manner (trend model: P = 0.002, uncorrected). These findings provide functional evidence to support the genetic association of MAPT with AD.

BackgroundSince the overall prognosis of very elderly patients is generally limited, admissions to intensive care in these patients are often restricted. Therefore, only very few information is available on the prognosis of nonagenarians after intensive care treatment. The aim of this study was to analyze the clinical characteristics and outcomes of very elderly patients (≥90 years) admitted to an intensive care unit (ICU).MethodsMonocentric, retrospective observational study of all patients aged ≥90 years admitted to the Department of Intensive Care Medicine with a total capacity of 132 ICU beds at the University Medical Center Hamburg in Germany between January 2008 and June 2013. A multivariate Cox regression analysis was used to identify risk factors for 28-day outcome.ResultsA total of 372 patients ≥90 years of age were admitted to one of the departments ICUs. The majority of patients (66.7 %) were admitted as an emergency admission, of which half underwent unscheduled surgery. 39.8 % of patients required support by mechanical ventilation and vasoactive drugs, and 1.9 % of patients received renal replacement. ICU and hospital mortality rates were 18.3 and 30.9 %, respectively. Overall survival at 1 year after hospital discharge was 34.9 %. Multivariate Cox regression analysis revealed creatinine, bilirubin, age, and necessity of catecholamines as independent risk factors and scheduled surgery as protective factor for 28-day outcome.ConclusionNearly 70 % of patients aged ≥90 years were discharged alive from hospital following treatment at the ICU, and more than half of them were still alive 1 year after their discharge. The results suggest that 1-year survival prognosis of very old ICU patients is not as poor as often perceived and that age per se should not be an exclusion criterion for ICU admission.Trial registration: WF-0561/13

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