960-86 Implications of Alternative Classifications of Sudden Cardiac Death: A Prospective Analysis of 109 Deaths in Defibrillator Trials

In order to explore the implications of using varied definitions of sudden cardiac death (SCD), a classification (CL) committee (3 cardiologists) prospectively evaluated 109 deaths over a period of 19 months in patients with an implantable cardioverter defibriliator (ICD). The basis for CL was the CAST approach with additional assessments of the consequences of considering autopsy and ICD interrogation information. Concordance and/or discordance between committee members was recorded.ResultsOf the 834 patients followed for 19 months, there were 109 deaths: 17 were classified SCD, 51 non-SCD. and 40 non-cardiac. Of the deaths classified as SCD, 10/17 were unwitnessed as compared to 6/51 non-SCD and 3/40 non-cardiac deaths; p < 0.001. ICD detections occurred in 5/17 SCD <1 hour, 7/17 SCD <6 hours; therefore, 10/17 SCD had no ICD detection or information available. There was committee discordance in 5/17 SCD compared to 18/51 non-SCD and 16/40 non-cardiac. SCD rates as high as 3.6% (30/834) can be estimated if all SCD cases Cl by ≥1 member was counted as SCD. Likewise. a SCD rate as low as 0.8% (7/834) is possible if SCD is limited to witnessed SCD ≤1 hour; (a 4-fold difference). Autopsy information was available in 29/109 deaths. In 7 cases, autopsy findings resulted in changing a “SCD” CL (5 witnessed; 2 unwitnessed) to either non-SCD or non-cardiac [ruptured abdominal (N=21 or thoracic aortic (N=1) aneurysm, acute MI (N=1), cerebral infarction (N=1). pulmonary embolism (N=2)]. Thus, had autopsy information been unavailable or not considered, the SCD rate would have increased to 24/834 12.9%). ICD interrogation was unavailable in 51/109 (47%), most commonly due to being buried with the patient or programmed off prior to death.ConclusionA 4-fold spectrum of SCD rates is possible to report from the identical data-set. ICD interrogation has significant limitations for use in death CL, in contrast to its utility in clinical management. Autopsy results clarify cause-specific mortality in deaths that are temporally quite “sudden.” Total mortality is the most objective primary end point

Relations between heart failure, ejection fraction, arrhythmia suppression and mortality: Analysis of the Cardiac Arrhythmia Suppression Trial

Objectives.We studied the relations between heart failure, ejection fraction, arrhythmia suppression and mortality.Background.Both left ventricular ejection fraction and functional class of heart failure are strongly associated with mortality after acute myocardial infarction. Both are also related to the presence of ventricular arrhythmias and have been identified as factors related to the ability to suppress ventricular arrhythmias. Little has been reported about the relations between these two factors and arrhythmia suppression or mortality.Methods.Baseline data from the Cardiac Arrhythmia Suppression Trial were used to define several categories of heart failure and to relate both the resulting categories and ejection fraction to arrhythmia suppression and mortality using logistic and survival regression analytic methodologies.Results.Regardless of the prospective baseline definition of heart failure used, the data consistently showed that heart failure was a more powerful predictor of subsequent congestive heart failure events and arrhythmia suppression and was equally powerful in predicting death. However, each variable provided incremental information when included in the prediction model. Heart failure and ejection fraction appeared to be independent predictors of death. Interactions were observed: A low ejection fraction was more predictive of failure of arrhythmia suppression in patients with than without evidence of heart failure before or at baseline; a low ejection fraction was more predictive of subsequent congestive heart failure events in patients without than with evidence of heart failure before or at baseline.Conclusions.Although heart failure as a prognostic feature appears to be somewhat superior to ejection fraction, both are powerful predictors of arrhythmia suppression and cardiac events in patients with ventricular arrhythmia after myocardial infarction. Each provides incremental prediction

Operational complexities in international clinical trials: a systematic review of challenges and proposed solutions

\ua9 Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ. OBJECTIVE: International trials can be challenging to operationalise due to incompatibilities between country-specific policies and infrastructures. The aim of this systematic review was to identify the operational complexities of conducting international trials and identify potential solutions for overcoming them. DESIGN: Systematic review. DATA SOURCES: Medline, Embase and Health Management Information Consortium were searched from 2006 to 30 January 2023. ELIGIBILITY CRITERIA: All studies reporting operational challenges (eg, site selection, trial management, intervention management, data management) of conducting international trials were included. DATA EXTRACTION AND SYNTHESIS: Search results were independently screened by at least two reviewers and data were extracted into a proforma. RESULTS: 38 studies (35 RCTs, 2 reports and 1 qualitative study) fulfilled the inclusion criteria. The median sample size was 1202 (IQR 332-4056) and median number of sites was 40 (IQR 13-78). 88.6% of studies had an academic sponsor and 80% were funded through government sources. Operational complexities were particularly reported during trial set-up due to lack of harmonisation in regulatory approvals and in relation to sponsorship structure, with associated budgetary impacts. Additional challenges included site selection, staff training, lengthy contract negotiations, site monitoring, communication, trial oversight, recruitment, data management, drug procurement and distribution, pharmacy involvement and biospecimen processing and transport. CONCLUSIONS: International collaborative trials are valuable in cases where recruitment may be difficult, diversifying participation and applicability. However, multiple operational and regulatory challenges are encountered when implementing a trial in multiple countries. Careful planning and communication between trials units and investigators, with an emphasis on establishing adequately resourced cross-border sponsorship structures and regulatory approvals, may help to overcome these barriers and realise the benefits of the approach. OPEN SCIENCE FRAMEWORK REGISTRATION NUMBER: osf-registrations-yvtjb-v1

Changes in precipitating snow chemistry with location and elevation in the California Sierra Nevada

Orographic snowfall in the Sierra Nevada Mountains is an important source of water for California and can vary significantly on an annual basis. The microphysical properties of orographic clouds and subsequent formation of precipitation are impacted, in part, by aerosols of varying size, number, and chemical composition, which are incorporated into clouds formed along the Sierra barrier. Herein, the physicochemical properties and sources of insoluble residues and soluble ions found in precipitation samples were explored for three sites of variable elevation in the Sierra Nevada during the 2012–2013 winter season. Residues were characterized using a suite of physicochemical techniques to determine the size‐resolved number concentrations and associated chemical composition. A transition in the aerosol sources that served as cloud seeds or were scavenged in‐cloud and below‐cloud was observed as a function of location and elevation. Anthropogenic influence from the Central Valley was dominant at the two lowest elevation sites (1900 and 2200 m above mean sea level (AMSL)), whereas long‐range transported mineral dust was a larger contributor at the highest elevation site where cleaner conditions were observed (2600 m AMSL). The residues and soluble ions observed provide insight into how multiple aerosol sources can impact cloud and precipitation formation processes, even over relatively small spatial scales. The transition with increasing elevation to aerosols that serve as ice nucleating particles may impact the properties and extent of snowfall in remote mountain regions where snowpack provides a vital supply of water.Key PointsPhysiochemical properties of particles found in precipitation were determinedBoth anthropogenic and natural sources contributed to the snow residue chemistrySnow residue sources varied depending on location and elevationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/1/jgrd53083-sup-0001-SI.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/2/jgrd53083_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133563/3/jgrd53083.pd

Corrigendum to “Randomized phase 2 trial and open-label extension of domagrozumab in Duchenne muscular dystrophy” [Neuromuscular Disorders, Vol. 30 (6) 2020, 492-502] (Neuromuscular Disorders (2020) 30(6) (492–502), (S0960896620301188), (10.1016/j.nmd.2020.05.002))

This article reported on the results from a phase 2 trial of domagrozumab and its open-label extension in patients with Duchenne muscular dystrophy (Clinicaltrials.gov identifiers: NCT02310763 and NCT02907619). The manuscript also provided results on two secondary endpoints for magnetic resonance imaging (MRI), muscle volume and muscle volume index. The authors regret that, following publication of the results and in preparation for a separate publication on MRI results from this trial, the MRI images were reviewed and segmentation errors were identified. As a result, the team worked to (1) Perform a rigorous quality inspection of all analysed data; (2) Identify cases where there were incorrect segmentations; (3) correct segmentation errors; (4) Re-analyse all data with correct segmentation. Using the updated MRI data, the MMRM analysis showed there was a change in the significance of secondary endpoints evaluating Thigh Muscle Volume and Muscle Volume Index. No significant differences between treatment groups in muscle volume measures were found in the original analysis. These results have not altered the overall interpretation of the study results but do necessitate revisions to the article. These data confirm that the trial design and execution adequately tested the hypothesis that myostatin inhibition would slow or delay the loss of function in patients with Duchenne muscular dystrophy (DMD). The increase in muscle volume observed by MRI in patients with DMD treated with domagrozumab is in accordance with mechanism of action for domagrozumab, which targets myostatin, a negative regulator of muscle growth. The increase in muscle volume did not lead to a clinical benefit in patients with DMD. The primary endpoint (4 stair climb) did not meet statistical significance, nor did the other functional tests. The study was terminated due to lack of efficacy. Full details of the needed revisions are as follows: 1. In the results section 3.6 (page 8, second paragraph), we reported no significant differences in mean percent change from baseline between domagrozumab and placebo for both muscle volume and muscle volume index. This paragraph was replaced with the following text: “There was a significant difference between domagrozumab and placebo in the mean percent change from baseline in thigh muscle volume at Week 17 (difference 2.945%, P=0.0087) and Week 49 (differences 4.087%, P=0.0298), and in muscle volume index at Week 33 (difference 2.612%, P=0.0376) and Week 49 (differences3.208%, P=0.0411).” 2. In the discussion (page 9), the following sentence, “Although neither muscle volume nor muscle volume index measures were statistically significant in this study, they are both consistent with a potential anabolic effect.” was replaced with, “The increase in muscle volume observed on MRI in patients with DMD treated with domagrozumab, is in accordance with mechanism of action for this compound which targets myostatin, a negative regulator of muscle growth. However, the increase in muscle volume did not lead to a clinical benefit (improved function) in patients with DMD.” 3. In view of the correction to the Results section, this is now reflected in the abstract which has changed to read: “There were no significant between-group differences in secondary clinical endpoints, except for the thigh muscle volume and muscle volume index measures (P\u3c0.05).” The authors would like to apologise for any inconvenience caused

Maize Cultivar Performance under Diverse Organic Production Systems

Maize (Zea mays L.) performance can vary widely between different production systems. The need for high-performing hybrids for organic systems with wide adaptation to various macroenvironments is becoming increasingly important. The goal of this study was to characterize inbred lines developed by distinct breeding programs for their combining ability and hybrid yield performance across diverse organic environments. Parent lines were selected from five different breeding programs to give a sample of publically available germplasm with potential for use in organic production systems with expired plant variety protection (Ex-PVP) and current commercial inbreds as benchmarks. A North Carolina Design II mating design was used to produce all possible cross combinations between seven lines designated as males and seven lines designated as females. A significantly positive general combining ability for the female inbred UHF134 suggests that it performs well in hybrid combination. Significant general combining ability was not observed for any male inbred line in this study. Several significantly positive specific combining abilities suggest that nonadditive genetic effects play an important role in determining yield in this germplasm. Further analysis revealed that hybrids containing either an Ex-PVP line or a commercial inbred line were on average superior to hybrids containing only inbreds developed by the cooperators of this study. This demonstrates the utility of testing inbreds from diverse sources when developing hybrids for organic production systems

The XMM Cluster Survey: The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback

Using a sample of 123 X-ray clusters and groups drawn from the XMM-Cluster Survey first data release, we investigate the interplay between the brightest cluster galaxy (BCG), its black hole, and the intra-cluster/group medium (ICM). It appears that for groups and clusters with a BCG likely to host significant AGN feedback, gas cooling dominates in those with Tx > 2 keV while AGN feedback dominates below. This may be understood through the sub-unity exponent found in the scaling relation we derive between the BCG mass and cluster mass over the halo mass range 10^13 < M500 < 10^15Msol and the lack of correlation between radio luminosity and cluster mass, such that BCG AGN in groups can have relatively more energetic influence on the ICM. The Lx - Tx relation for systems with the most massive BCGs, or those with BCGs co-located with the peak of the ICM emission, is steeper than that for those with the least massive and most offset, which instead follows self-similarity. This is evidence that a combination of central gas cooling and powerful, well fuelled AGN causes the departure of the ICM from pure gravitational heating, with the steepened relation crossing self-similarity at Tx = 2 keV. Importantly, regardless of their black hole mass, BCGs are more likely to host radio-loud AGN if they are in a massive cluster (Tx > 2 keV) and again co-located with an effective fuel supply of dense, cooling gas. This demonstrates that the most massive black holes appear to know more about their host cluster than they do about their host galaxy. The results lead us to propose a physically motivated, empirical definition of 'cluster' and 'group', delineated at 2 keV.Comment: Accepted for publication in MNRAS - replaced to match corrected proo

Low dose Btk inhibitors selectively block platelet activation by CLEC-2

Inhibitors of the tyrosine kinase Btk have been proposed as novel antiplatelet agents. In this study we show that low concentrations of the Btk inhibitor ibrutinib block CLEC-2-mediated activation and tyrosine phosphorylation including Syk and PLCγ2 in human platelets. Activation is also blocked in patients with X-linked agammaglobulinaemia (XLA) caused by a deficiency or absence of Btk. In contrast, the response to GPVI is delayed in the presence of low concentrations of ibrutinib or in patients with XLA, and tyrosine phosphorylation of Syk is preserved. A similar set of results is seen with the second-generation inhibitor, acalabrutinib. The differential effect of Btk inhibition in CLEC-2 relative to GPVI signalling is explained by the positive feedback role involving Btk itself, as well as ADP and thromboxane A2 mediated activation of P2Y12 and TP receptors, respectively. This feedback role is not seen in mouse platelets and, consistent with this, CLEC-2-mediated activation is blocked by high but not by low concentrations of ibrutinib. Nevertheless, thrombosis was absent in 8 out of 13 mice treated with ibrutinib. These results show that Btk inhibitors selectively block activation of human platelets by CLEC-2 relative to GPVI suggesting that they can be used at ‘low dose’ in patients to target CLEC-2 in thrombo-inflammatory disease

Multi-site investigation of strategies for the implementation of CYP2C19 genotype-guided antiplatelet therapy

CYP2C19 genotype-guided antiplatelet therapy following percutaneous coronary intervention is increasingly implemented in clinical practice. However, challenges such as selecting a testing platform, communicating test results, building clinical decision support processes, providing patient and provider education, and integrating methods to support the translation of emerging evidence to clinical practice are barriers to broad adoption. In this report, we compare and contrast implementation strategies of 12 early adopters, describing solutions to common problems and initial performance metrics for each program. Key differences between programs included the test result turnaround time and timing of therapy changes which are both related to CYP2C19 testing model and platform used. Sites reported the need for new informatics infrastructure, expert clinicians such as pharmacists to interpret results, physician champions, and ongoing education. Consensus lessons learned are presented to provide a path forward for those seeking to implement similar clinical pharmacogenomics programs within their institutions. This article is protected by copyright

Plasmodium falciparum Hep1 is required to prevent the self aggregation of PfHsp70-3

The majority of mitochondrial proteins are encoded in the nucleus and need to be imported from the cytosol into the mitochondria, and molecular chaperones play a key role in the efficient translocation and proper folding of these proteins in the matrix. One such molecular chaperone is the eukaryotic mitochondrial heat shock protein 70 (Hsp70); however, it is prone to self-aggregation and requires the presence of an essential zinc-finger protein, Hsp70-escort protein 1 (Hep1), to maintain its structure and function. PfHsp70-3, the only Hsp70 predicted to localize in the mitochondria of P. falciparum, may also rely on a Hep1 orthologue to prevent self-aggregation. In this study, we identified a putative Hep1 orthologue in P. falciparum and co-expression of PfHsp70-3 and PfHep1 enhanced the solubility of PfHsp70-3. PfHep1 suppressed the thermally induced aggregation of PfHsp70-3 but not the aggregation of malate dehydrogenase or citrate synthase, thus showing specificity for PfHsp70-3. Zinc ions were indeed essential for maintaining the function of PfHep1, as EDTA chelation abrogated its abilities to suppress the aggregation of PfHsp70-3. Soluble and functional PfHsp70-3, acquired by co-expression with PfHep-1, will facilitate the biochemical characterisation of this particular Hsp70 protein and its evaluation as a drug target for the treatment of malaria