SUMMARYTamoxifen-inducible Cre-mediated manipulation of animal genomes has achieved wide acceptance over the last decade, with numerous important studies heavily relying on this technique. Recently, a number of groups have reported transient complications of using this protocol in the heart. In the present study we observed a previously unreported focal fibrosis and depressed left-ventricular function in tamoxifen-treated αMHC-MerCreMer-positive animals in a Tβ4shRNAflox × αMHC-MerCreMer cross at 6–7 weeks following standard tamoxifen treatment, regardless of the presence of the floxed transgene. The phenotype was reproduced by treating mice from the original αMHC-MerCreMer strain with tamoxifen. In the acute phase after tamoxifen treatment, cell infiltration into the myocardium was accompanied by increased expression of pro-inflammatory cytokines (IL-1β, IL-6, TNFα, IFNγ, Ccl2) and markers of hypertrophy (ANF, BNP, Col3a1). These observations highlight the requirement for including tamoxifen-treated MerCreMer littermate controls to avert misinterpretation of conditional mutant phenotypes. A survey of the field as well as the protocols presented here suggests that controlling the parameters of tamoxifen delivery is important in avoiding the chronic MerCreMer-mediated cardiac phenotype reported here.

Serum and glucocorticoid inducible kinase 1 (SGK1) plays a pivotal role in early angiogenesis during embryonic development. In this study, we sought to define the SGK1 downstream signalling pathways in the adult heart and to elucidate their role in cardiac neo-angiogenesis and wound healing after myocardial ischemia. To this end, we employed a viable SGK1 knockout mouse model generated in a 129/SvJ background. Ablation of SGK1 in these mice caused a significant decrease in phosphorylation of SGK1 target protein NDRG1, which correlated with alterations in NF-κB signalling and expression of its downstream target protein, VEGF-A. Disruption of these signalling pathways was accompanied by smaller heart and body size. Moreover, the lack of SGK1 led to defective endothelial cell (ECs) migration and tube formation in vitro, and increased scarring with decreased angiogenesis in vivo after myocardial infarct. This study underscores the importance of SGK1 signalling in cardiac neo-angiogenesis and wound healing after an ischemic insult in vivo.

We established rapid local viral sequencing to document the genomic diversity of severe acute respiratory syndrome coronavirus 2 entering Uganda. Virus lineages closely followed the travel origins of infected persons. Our sequence data provide an important baseline for tracking any further transmission of the virus throughout the country and region.

The aim of this study was to investigate whether supplemental IGF-1Ea transgene expression induces activation of local cardiac and bone marrow stem cell population to mediate mammalian heart repair. In physiologic conditions, cardiac overexpression of the IGF-1Ea propeptide is associated with an enrichment of c-Kit/Sca-1 positive side population cells in the bone marrow and the occurrence of an endothelial-primed CD34 positive side population in the heart. This cellular profile is shown here to correlate with the expression of cytokines involved in stem cell mobilization and vessel formation. This molecular and cellular interplay favored IGF-1Ea-mediated vessel formation in injured hearts. The physiologic and pathologic connection between cytokines and stem cells in response to IGF-1Ea may represent an important model to understand how to elicit endogenous reparative signaling.

BackgroundIn septic shock, cardiovascular resuscitation using catecholamine vasopressors and inotropes is standard therapy, but catecholamines have important side effects. Levosimendan (Simdax®; Orion Pharma, Newbury, UK) is a calcium-sensitising drug with inotropic and other properties that may have a role in sepsis.ObjectivesTo determine, in adult septic shock, whether or not levosimendan reduces the incidence and severity of acute organ dysfunction, the effect of levosimendan on individual organ function and the safety profile of levosimendan.DesignMulticentre, randomised, double-blind, parallel-group, placebo-controlled study.SettingUK intensive care units.ParticipantsAdult patients with sepsis and cardiovascular failure requiring vasopressors to maintain blood pressure despite adequate fluid resuscitation.InterventionLevosimendan, at a dosage of 0.05–0.2 µg/kg/minute, compared with placebo for 24 hours, in addition to standard care, within 24 hours of meeting inclusion criteria.Main outcome measureThe primary outcome was mean Sequential Organ Failure Assessment (SOFA) score on the intensive care unit after randomisation to a maximum of 28 days. Secondary outcomes were time to extubation, survival up to 6 months and serious adverse events.ResultsIn total, 2382 patients were screened at 34 centres, of whom 516 were randomised to treatment, 259 to levosimendan and 257 to placebo. Baseline characteristics were well balanced across treatment arms. There was no significant difference in mean ± standard deviation (SD) SOFA score between the levosimendan group (6.7, SD 4.0) and the placebo group (6.1, SD 3.9) [mean difference 0.61, 95% confidence interval (CI) –0.07 to 1.29]. The 28-day mortality rate was 34.5% and 30.9% in the levosimendan and placebo groups, respectively (absolute difference 3.6%, 95% CI –4.5% to 11.7%). Patients in the levosimendan group were less likely to be successfully extubated over 28 days than patients in the placebo group (hazard ratio 0.77, 95% CI 0.60 to 0.97). More patients in the levosimendan group had supraventricular tachyarrhythmias (3.1% vs. 0.4%; absolute difference 2.7%, 95% CI 0.1% to 5.3%), but there was no overall difference in serious adverse events.ConclusionsIn the population of septic shock patients randomised to treatment in this study, the addition of levosimendan to standard medical care did not reduce organ dysfunction or mortality. Levosimendan was associated with a reduced likelihood of successful extubation and an increased risk of supraventricular tachyarrhythmias.LimitationsThis was a trial of levosimendan added to standard care rather than a comparison against an alternative inotrope such as dobutamine. No echocardiographic analyses were performed to provide detailed information about changes in myocardial function; therefore, this trial cannot provide guidance as to which inotrope (if any) is best to use in the management of sepsis if a very low cardiac index is present.Future workLevosimendan could be compared against dobutamine and placebo in patients with a very low cardiac output in sepsis to test which, if any, inotrope should be used in this select group.Trial registrationCurrent Controlled Trials ISRCTN12776039.FundingThis project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council and National Institute for Health Research (NIHR) partnership. Study drugs were provided by Orion Pharma and additional research funds were provided by Tenax Therapeutics. The study was supported by the NIHR Biomedical Research Centre based at Imperial College, London, and the UK Intensive Care Foundation.