ZO-1 interacts with YB-1 in endothelial cells to regulate stress granule formation during angiogenesis.

Zonula occludens-1 (ZO-1) is involved in the regulation of cell-cell junctions between endothelial cells (ECs). Here we identify the ZO-1 protein interactome and uncover ZO-1 interactions with RNA-binding proteins that are part of stress granules (SGs). Downregulation of ZO-1 increased SG formation in response to stress and protected ECs from cellular insults. The ZO-1 interactome uncovered an association between ZO-1 and Y-box binding protein 1 (YB-1), a constituent of SGs. Arsenite treatment of ECs decreased the interaction between ZO-1 and YB-1, and drove SG assembly. YB-1 expression is essential for SG formation and for the cytoprotective effects induced by ZO-1 downregulation. In the developing retinal vascular plexus of newborn mice, ECs at the front of growing vessels express less ZO-1 but display more YB-1-positive granules than ECs located in the vascular plexus. Endothelial-specific deletion of ZO-1 in mice at post-natal day 7 markedly increased the presence of YB-1-positive granules in ECs of retinal blood vessels, altered tip EC morphology and vascular patterning, resulting in aberrant endothelial proliferation, and arrest in the expansion of the retinal vasculature. Our findings suggest that, through its interaction with YB-1, ZO-1 controls SG formation and the response of ECs to stress during angiogenesis.

GPC-100, a novel CXCR4 antagonist, improves in vivo hematopoietic cell mobilization when combined with propranolol.

Autologous Stem Cell Transplant (ASCT) is increasingly used to treat hematological malignancies. A key requisite for ASCT is mobilization of hematopoietic stem cells into peripheral blood, where they are collected by apheresis and stored for later transplantation. However, success is often hindered by poor mobilization due to factors including prior treatments. The combination of G-CSF and GPC-100, a small molecule antagonist of CXCR4, showed potential in a multiple myeloma clinical trial for sufficient and rapid collection of CD34+ stem cells, compared to the historical results from the standards of care, G-CSF alone or G-CSF with plerixafor, also a CXCR4 antagonist. In the present study, we show that GPC-100 has high affinity towards the chemokine receptor CXCR4, and it potently inhibits ß-arrestin recruitment, calcium flux and cell migration mediated by its ligand CXCL12. Proximity Ligation Assay revealed that in native cell systems with endogenous receptor expression, CXCR4 co-localizes with the beta-2 adrenergic receptor (ß2AR). Co-treatment with CXCL12 and the ß2AR agonist epinephrine synergistically increases ß-arrestin recruitment to CXCR4 and calcium flux. This increase is blocked by the co-treatment with GPC-100 and propranolol, a non-selective beta-adrenergic blocker, indicating a functional synergy. In mice, GPC-100 mobilized more white blood cells into peripheral blood compared to plerixafor. GPC-100 induced mobilization was further amplified by propranolol pretreatment and was comparable to mobilization by G-CSF. Addition of propranolol to the G-CSF and GPC-100 combination resulted in greater stem cell mobilization than the G-CSF and plerixafor combination. Together, our studies suggest that the combination of GPC-100 and propranolol is a novel strategy for stem cell mobilization and support the current clinical trial in multiple myeloma registered as NCT05561751 at www.clinicaltrials.gov.

Diagnoses, management patterns, and outcomes of cardiac sarcoidosis in South Africa.

Background: Sarcoidosis is an idiopathic multiorgan disease characterized by tissue infiltration by noncaseating granulomas. Clinical cardiac involvement is reported in approximately 5% of patients. However, the frequency of cardiac involvement is found to be higher on autopsy and in advanced imaging studies such as cardiac magnetic resonance imaging. Objective: The purpose of this study was to determine contemporary diagnoses, management, and outcomes of cardiac sarcoidosis (CS) in South Africa. Methods: Clinical records of patients diagnosed with CS between January 2000 and December 2021 were reviewed. Results: Twenty-two patients were diagnosed with CS during the study period. The patients had a mean (± SD) age of 45.2 ± 12.3 years at the time of presentation. CS diagnostic rates increased from 4.5% in 2000-2005 to 45.5% in 2016-2021. Fifteen of the 22 patients (68.2%) were newly diagnosed with sarcoidosis at the time of CS diagnosis, and 9 of the 15 (60%) had pulmonary involvement. Of the 22 patients diagnosed with CS, 13 (59.1%) presented in combination with heart block, 10 (45.5%) with ventricular arrhythmias, and 4 (18.2%) with heart failure. Five endomyocardial biopsies were performed, and all were nondiagnostic. However, 8 of 8 endobronchial ultrasound (EBUS)-guided biopsies of thoracic lymph nodes were diagnostic of sarcoidosis and, notably, excluded tuberculosis. Fourteen patients (63.6%) were treated with corticosteroids, 7 (31.8%) with azathioprine, 9 (40.9%) with amiodarone, and 16 (72.7%) with a cardiac implantable electronic device. After a mean follow-up period of 64.5 ± 50.5 months, no deaths had occurred. Conclusion: CS diagnostic rates have increased over time. Diagnostic endomyocardial biopsies have a low diagnostic yield, whereas EBUS-guided biopsy of thoracic lymph nodes is of crucial diagnostic utility.

EHRA expert consensus document on the management of arrhythmias in frailty syndrome, endorsed by the Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Latin America Heart Rhythm Society (LAHRS), and Cardiac Arrhythmia Society of Southern Africa (CASSA).

There is an increasing proportion of the general population surviving to old age with significant chronic disease, multi-morbidity, and disability. The prevalence of pre-frail state and frailty syndrome increases exponentially with advancing age and is associated with greater morbidity, disability, hospitalization, institutionalization, mortality, and health care resource use. Frailty represents a global problem, making early identification, evaluation, and treatment to prevent the cascade of events leading from functional decline to disability and death, one of the challenges of geriatric and general medicine. Cardiac arrhythmias are common in advancing age, chronic illness, and frailty and include a broad spectrum of rhythm and conduction abnormalities. However, no systematic studies or recommendations on the management of arrhythmias are available specifically for the elderly and frail population, and the uptake of many effective antiarrhythmic therapies in these patients remains the slowest. This European Heart Rhythm Association (EHRA) consensus document focuses on the biology of frailty, common comorbidities, and methods of assessing frailty, in respect to a specific issue of arrhythmias and conduction disease, provide evidence base advice on the management of arrhythmias in patients with frailty syndrome, and identifies knowledge gaps and directions for future research.

Clinical profile and outcomes of young patients treated with implantable cardioverter defibrillators at a South African tertiary hospital: a review of two decades of implantable cardioverter defibrillator implantation and follow up.

AIM: In young patients without atherosclerotic coronary artery disease, the aetiology of sudden cardiac death (SCD) has been described in Europe and North America. However, there are important regional variations and there are limited data on the aetiology and outcome of SCD in South Africa. The objective of this study was to determine the profile and outcomes of young patients treated with implantable cardioverter defibrillators (ICDs) at a South African tertiary hospital. METHODS: This study was designed as a retrospective review of patients aged 35 years or younger implanted with ICDs at Groote Schuur Hospital. RESULTS: During the study period, 38 patients younger than 35 years were implanted with ICDs. The mean (standard deviation) age at ICD implantation was 25.1 (7.6) years and 63.2% were male. A secondary-prevention ICD was implanted in 57.9% of the patient population, and primary prevention in the remaining 42.1%. Patients with secondary-prevention ICDs presented with ventricular tachycardia (59.1%), ventricular fibrillation (31.8%) and receipt of cardiopulmonary resuscitation but no recorded electrocardiograms (9.1%). Arrhythmogenic right ventricular cardiomyopathy (ARVC) was the leading cause of SCD in the secondary-prevention patient population (36.4%). Idiopathic dilated cardiomyopathy accounted for 50% of the primary-prevention patient population. After a median (interquartile range) follow up 32 (14-90) months, 7.9% died and 5.2% received a heart transplant; 42.1% of the study population received appropriate ICD shock therapies and 18.4% received inappropriate shock therapies. CONCLUSIONS: In this single-centre study from South Africa, ARVC and repaired congenital heart disease were the leading causes of SCD in patients younger than 35 years treated with secondary-prevention ICDs. Primary-prevention ICDs were frequently implanted for idiopathic dilated cardiomyopathy.

Causes of Heart Block in Young and Middle-Aged South Africans.

BACKGROUND: There is a paucity of data regarding the aetiology of atrioventricular heart block (AVB) in young and middle-aged patients, particularly from low- and middle-income countries. OBJECTIVE: To determine the aetiology of AVB in patients ≤ 55 years treated with transvenous pacemakers in a low- or middle-income country. METHODS: We performed a retrospective review of all patients who received a transvenous pacemaker for newly diagnosed AVB from 01/01/2013 to 31/12/2020 at Groote Schuur Hospital, Cape Town, South Africa. RESULTS: One thousand one hundred one (1101) consecutive patients received a permanent transvenous pacemaker for AVB. One hundred thirty-six patients (12.4%) were ≤ 55 years. The study patients' mean (standard deviation) age was 41 (11) years, and 48.5% were female. Third-degree AV block was diagnosed in 73.5%, 2:1 AV block in 8.1%, and Mobitz Ι second degree AV block in 5.9%. The aetiology of AVB could be determined in 97/136 (71.3%) patients. Forty-three of 136 (31.6%) patients were post-surgical, and 16/136 (11.8%) patients had developed AVB from an acute myocardial infarction. Cardiac Magnetic Resonance (CMR) imaging was performed in 26 patients: cardiac sarcoidosis was diagnosed in 7/26 patients. No pathology could be identified in 10/26 patients who had CMR. The aetiology of AVB remained unknown in 39/136 patients (28.7%). CONCLUSION: Prior valve surgery is the leading cause of AVB treated with a transvenous pacemaker in patients ≤ 55 years in this South African referral unit. Cardiac magnetic resonance imaging identified disease processes that require further management in many cases.

Effectiveness of implantable loop recorder and Holter electrocardiographic monitoring for the detection of arrhythmias in patients with peripartum cardiomyopathy.

BACKGROUND: Patients with peripartum cardiomyopathy (PPCM) are at increased risk of sudden cardiac death (SCD). However, the exact underlying mechanisms of SCD in PPCM remain unknown. By means of extended electrocardiographic monitoring, we aimed to systematically characterize the burden of arrhythmias occurring in patients with newly diagnosed PPCM. METHODS AND RESULTS: Twenty-five consecutive women with PPCM were included in this single-centre, prospective clinical trial and randomised to receiving either 24 h-Holter ECG monitoring followed by implantable loop recorder implantation (ILR; REVEAL XT, Medtronic®) or 24 h-Holter ECG monitoring alone. ILR + 24 h-Holter monitoring had a higher yield of arrhythmic events compared to 24 h-Holter monitoring alone (40% vs 6.7%, p = 0.041). Non-sustained ventricular tachycardia (NSVT) occurred in four patients (16%, in three patients detected by 24 h-Holter, and multiple episodes detected by ILR in one patient). One patient deceased from third-degree AV block with an escape rhythm that failed. All arrhythmic events occurred in patients with a severely impaired LV systolic function. CONCLUSIONS: We found a high prevalence of potentially life-threatening arrhythmic events in patients with newly diagnosed PPCM. These included both brady- and tachyarrhythmias. Our results highlight the importance of extended electrocardiographic monitoring, especially in those with severely impaired LV systolic function. In this regard, ILR in addition to 24 h-Holter monitoring had a higher yield of VAs as compared to 24 h-Holter monitoring alone. In settings where WCDs are not readily available, ILR monitoring should be considered in patients with severely impaired LV systolic dysfunction, especially after uneventful 24 h-Holter monitoring. TRIAL REGISTRATION: Pan African Clinical Trials Registry: PACTR202104866174807. Extended electrocardiographic monitoring for the detection of arrhythmias in PPCM. (CHB, complete heart block/third degree AV block; ECG, electrocardiogram; ILR, implantable loop recorder; NSVT, non-sustained ventricular tachycardia; PPCM, peripartum cardiomyopathy).

Feasibility and safety of interventional electrophysiology and catheter ablation in the South African public sector: Challenges and opportunities for comprehensive cardiac electrophysiology in South Africa.

Aims: The spectrum and outcomes of catheter ablation procedures performed in South Africa are unknown, and therefore, the feasibility of interventional electrophysiology in the South African public sector is undetermined. Methods and Results: This study was a retrospective review of all patients that underwent invasive electrophysiology procedures and catheter ablation at Groote Schuur Hospital (GSH) and the University of Cape Town Private Academic Hospital (UCTPAH) between 01 January 2013 and 31 December 2020.One thousand one hundred eighty-six invasive electrophysiology procedures were performed during the study period. Of these were 1102 catheter ablation procedures. There were 76 redo catheter ablation procedures, predominantly for atrial fibrillation (AF), which accounted for 39% (30/76) of the repeat procedures. There were only 0.8% (9/1102) catheter ablation related complications which were mostly access related. Atrial fibrillation accounted for most of the ablation procedures, 28.9% (318/1102); these were mainly performed at UCTPAH than at GSH, 300 vs 18 p < .0001. Cavotricuspid isthmus (CTI) dependent atrial flutter ablation was the second most commonly performed catheter ablation procedure, accounting for 21.6% (238/1102) of the catheter ablation procedures. More CTI dependent atrial flutter ablations were performed at GSH than a UCTPAH, 156 vs 82 p < .0001. The overall success rate of catheter ablation was 92%. Conclusion: A broad spectrum of catheter ablation procedures was performed with a high success rate and limited complications, thus demonstrating the feasibility of safe cardiac electrophysiology and catheter ablation in the South African public sector.

Two decades of implantable cardioverter defibrillator implantation and follow-up at a South African referral centre: trends, indications and long-term outcomes in a resource-limited setting.

Background: More than two-thirds of cardiovascular deaths occur in low- and middle-income countries. Sudden cardiac deaths (SCD) from ventricular arrhythmias are an important cause of cardiovascular deaths. Implantable cardioverter defibrillators (ICD) are an important therapeutic strategy for detecting and terminating ventricular arrhythmias in patients at risk of SCD. The profile of patients treated with ICDs in South Africa is unknown. Further, with changing lines of evidence, the implantation trends are undetermined. The objectives of this study were to determine the profile of ICD recipients and implantation trends in a South African quaternary hospital. Methods: This was a retrospective review of all patients implanted with ICDs at Groote Schuur Hospital from 01 January 1998 to 31 December 2020. A standardised data collection form was used to collect baseline demographic data, information on clinical presentation and ICD follow-up data for the history of ICD shock therapies. Results: A total of 253 ICDs were implanted; 75% for secondary prevention and 25% for primary prevention. 67.2% of the implanted ICDs were single-chamber ICDs, dual-chamber ICDs were implanted in 12.3% and Cardiac resynchronisation with a defibrillator (CRT-D) in 20.6%. There was an upward trajectory of ICD implantations during the study period. Increasing numbers of dual-chamber devices and CRT-D were implanted over time. ICD recipients had a mean (standard deviation) age of 50 (14) years and were predominantly male (69%). Primary prevention ICD recipients were younger than secondary prevention recipients, with a mean (SD) age of 46 (14) years versus 51 (14) years, p = 0.019. The secondary prevention group presented with ventricular tachycardia in 81%, ventricular fibrillation in 13% and cardiopulmonary resuscitation without documented heart rhythm in 5.3% (10/190). After a median (interquartile range) follow-up of 44 (15; 93) months, there was an overall mortality rate of 16.2%, with no mortality difference between the primary and secondary prevention patient groups. Conclusion: There is an increase in the annual number of ICDs implanted at a South African referral centre. ICDs are predominantly implanted for secondary prevention. However, over time the number of devices implanted for primary prevention is steadily increased. During follow-up, there was no mortality difference between the primary prevention and the secondary prevention groups.

Stroke risk prediction in patients with atrial fibrillation with and without rheumatic heart disease.

AIMS: Patients with atrial fibrillation (AF) and rheumatic heart disease (RHD), especially mitral stenosis, are assumed to be at high risk of stroke, irrespective of other factors. We aimed to re-evaluate stroke risk factors in a contemporary cohort of AF patients. METHODS AND RESULTS: We analysed data of 15 400 AF patients presenting to an emergency department and who were enrolled in the global RE-LY AF registry, representing 47 countries from all inhabited continents. Follow-up occurred at 1 year after enrolment. A total of 1788 (11.6%) patients had RHD. These patients were younger (51.4±15.7 vs. 67.8±13.6 years), more likely to be female (66.2% vs. 44.7%) and had a lower mean CHA2DS2-VASc score (2.1±1.7 vs. 3.7±2.2) as compared to patients without RHD (all P<0.001). Significant mitral stenosis (average mean transmitral gradient 11.5±6.5 mmHg) was the predominant valve lesion in those with RHD (59.6%). Patients with RHD had a higher baseline rate of anticoagulation use (60.4% vs. 45.2%, P<0.001). Unadjusted stroke rates at 1 year were 2.8% and 4.1% for patients with and without RHD, respectively. The performance of the CHA2DS2-VASc score was modest in both groups [stroke at 1 year, c-statistics 0.69, 95% confidence interval (CI) 0.60-0.78 and 0.63, 95% CI 0.61-0.66, respectively]. In the overall cohort, advanced age, female sex, prior stroke, tobacco use, and non-use of anticoagulation were predictors for stroke (all P<0.05). Mitral stenosis was not associated with stroke risk (adjusted odds ratio 1.07, 95% CI 0.67-1.72, P=0.764). CONCLUSION: The performance of the CHA2DS2-VASc score was modest in AF patients both with and without RHD. In this cohort, moderate-to-severe mitral stenosis was not an independent risk factor for stroke.

Teratogenicity and toxicity of the new BPA alternative TMBPF, and BPA, BPS, and BPAF in chick embryonic development.

Bisphenol A (BPA) is a widely known, yet controversial reproductive toxin, capable of inducing reproductive, developmental, and somatic growth defects across species. Due to scientific findings and public concern, companies have developed BPA alternatives remarkably similar to BPA. However, these alternatives have had much less testing and oversight, yet they are already being mass-produced and used across industries from plastics to food-contact coatings. The newest one, tetramethyl bisphenol F (TMBPF), is the least well-studied and has never been investigated in embryological models, however it continues to be mass produced and found in various products. Here, we used the chicken embryotoxicity screening test to compare the toxicities and potencies of several BPA analogs including TMBPF. We exposed developing chicken (Gallus gallus domesticus) embryos in ovo, from embryonic day 5 to 12 (E5-12), to increasing concentrations of BPA, bisphenol S (BPS), bisphenol AF (BPAF), and TMBPF, from 0.003 to 30 µM, and analyzed their developmental and toxic effects. The bisphenols significantly impaired development, growth, and survival in a dose-dependent manner, even at low, environmentally relevant concentrations of 3-30 nM. There was severely reduced growth and developmental delay, with exposed embryos averaging half the size and weight of control vehicle-treated embryos. The most common and severe dysmorphologies were craniofacial, eye, gastrointestinal, and body pigmentation abnormalities. The bisphenols caused dose-dependent toxicity with the lowest LC50s (lethal concentration with 50% survival) ever demonstrated in chick embryos, at 0.83-2.92 µM. Notably, TMBPF was the second-most toxic and teratogenic of all chemicals tested (rank order of BPAF > TMBPF > BPS > BPA). These results underscore the adverse effects of BPA replacements on early embryo development and may have implications for reproductive health and disease across species, including pregnancy exposures in humans.

RNA Interference (RNAi) Screening in Cultured Drosophila Cells.

Genetic perturbation assays have been crucial to the discovery of molecular pathways that drive diverse biological processes. RNA interference (RNAi)-mediated depletion of gene products represents a powerful means of elucidating gene function, as it allows one to systematically probe the phenotypic effects resulting from the functional loss of specific targets. The relative ease of use of RNAi technologies in cultured cells has allowed the design and implementation of genome-wide investigations to systematically reveal gene function. In this chapter, we describe methods for high-throughput RNAi-mediated loss-of-function studies in cultured cells of Drosophila melanogaster. First, we describe the in vitro synthesis of double stranded RNAs (dsRNAs) from a genome-wide Drosophila RNAi library. Next, we outline the procedures used to carry out high-throughput RNAi screens using a cell bathing approach and high-content screening microscopy, illustrating how these experiments can be utilized to study specific cellular contexts, such as cellular stress. Finally, we illustrate some approaches commonly employed to validate the depletion of identified gene candidates.

Puromycin Labeling Coupled with Proximity Ligation Assays to Define Sites of mRNA Translation in Drosophila Embryos and Human Cells.

Genetic mutations, whether they occur within protein-coding or noncoding regions of the genome, can affect various aspects of gene expression by influencing the complex network of intra- and intermolecular interactions that occur between cellular nucleic acids and proteins. One aspect of gene expression control that can be impacted is the intracellular trafficking and translation of mRNA molecules. To study the occurrence and dynamics of translational regulation, researchers have developed approaches such as genome-wide ribosome profiling and artificial reporters that enable single molecule imaging. In this paper, we describe a complementary and optimized approach that combines puromycin labeling with a proximity ligation assay (Puro-PLA) to define sites of translation of specific mRNAs in tissues or cells. This method can be used to study the mechanisms driving the translation of select mRNAs and to access the impact of genetic mutations on local protein synthesis. This approach involves the treatment of cell or tissue specimens with puromycin to label nascently translated peptides, rapid fixation, followed by immunolabeling with appropriate primary and secondary antibodies coupled to PLA oligonucleotide probes, ligation, amplification, and signal detection via fluorescence microscopy. Puro-PLA can be performed at small scale in individual tubes or in chambered slides, or in a high-throughput setup with 96-well plate, for both in situ and in vitro experimentation.

Cytotoxic and apoptotic data of BPA and BPA alternatives TMBPF, BPAF, and BPS in female adult rat and human stem cells.

Here, we used female adult rat adipose-derived stem cells (rASCs) and human adipose-derived stem cells (hASCs) to compare the toxicities and potencies of several widespread environmental toxins that may be endocrine-disrupting chemicals, including bisphenol A (BPA), and the newer BPA alternatives bisphenol S (BPS), bisphenol AF (BPAF), and tetramethyl bisphenol F (TMBPF). Adult stem cells were cultured to 80% confluency in vitro and then exposed to BPA (1 and 10 µM), 17ß-estradiol (E2; 10 µM), BPS (1 and 10 µM), BPAF (3 × 10-3-30 µM), TMBPF (0.01-50 µM), or control media alone (with 0.01% ethanol) for varying time intervals from 20 min to 5 hrs. Using several cellular assays, the levels of cell death, apoptosis, caspase-6 activation, and potencies were compared across chemical treatments and vehicle-treated controls. There was significantly decreased cell viability and increased apoptosis in rat and human stem cells treated with each BPA analog, as early as 20 min of exposure, and at low doses. With higher magnification, higher resolution imaging it was evident that in many of the BPA analog-treated cells, the Apopxin Deep Red dye indicative of apoptosis was localized to the cytoplasmic compartments of cells, while the nuclear green DCS1 dye indicative of late-stage apoptosis and necrosis was localized to the nuclei of cells. Notably, BPAF and TMBPF showed cytotoxicity in a dose-dependent manner (BPAF LC50 = 0.014 µM (rASCs) and 0.009 µM (hASCs); TMBPF LC50 = 0.88 µM (rASCs) and 0.06 µM (hASCs); lethal concentration with 50% survival). The rank order of potency was BPAF>TMBPF>BPA>BPS. The majority of cell death was due to apoptosis as indicated by high levels of activated caspase-6 in the cytoplasm of almost 100% of cells treated with the BPA analogs. This data allows for further confirmation of caspase-6-mediated apoptosis using higher magnification imaging that definitively demonstrate the cytotoxic and apoptotic effects of these BPA analogs. For a complete description, interpretation, and discussion of the data refer to the article in press [1].

Experience of cardiac implantable electronic device lead removal from a South African tertiary referral centre.

BACKGROUND: The rate of cardiac implantable electronic device (CIED) implantation in low- and middle-income countries is increasing. Patients recieving these devices are frequently older and with multiple co-morbidities, which may later lead to complications requiring CIED removal. CIED removals are associated with life-threatening complications. However, high sucesss rates are reported in high-income countries. The purpose of this study was to report on the experience of CIED removal in a resource-constrained setting. METHODS: In this retrospective study, we included consecutive adult patients admitted to Groote Schuur Hospital and the University of Cape Town Private Academic Hospital for CIED removal from 1 January 2008 to 31 December 2019. RESULTS: During the study period, 53 patients underwent CIED removal (26 extractions and 27 explants). The patients had a mean (standard deviation) age of 59.1 (16.0) years. A history of systemic hypertension was present in 50.9% of patients, diabetes mellitus in 30.2% and dilated cardiomyopathy in 47.2%. Complete heart block was the leading indication for CIED implantation (37.7%), and device infection was the leading indication for removal (69.2%). CIEDs were removed after a median (interquantile range) of 243 (53-831) days. There were 40 leads extracted and 35 explants. Lead extractions were perfomed in the cardiac catheterisation laboratory under general anaesthesia via a percutaneous transvenous superior approach. There was one major and one minor complication related to lead extraction. CONCLUSIONS: CIED infections were the primary indication for CIED removal in a tertiary referral centre in South Africa. Despite being a low-volume centre, we report a high percutaneous transvenous extraction success rate with low complication rate; results which are comparable to high-volume centres.

BPA and BPA alternatives BPS, BPAF, and TMBPF, induce cytotoxicity and apoptosis in rat and human stem cells.

Bisphenol A (BPA) is a ubiquitous industrial chemical found in everyday plastic products and materials. Due to scientific findings on the reproductive, developmental, and cellular defects caused by BPA and heightened public awareness, manufacturers have begun to use new chemicals in place of BPA in "BPA-free" products. These alternatives are chemical analogs of BPA and include dozens of new compounds that have undergone relatively little testing and oversight, including: bisphenol S (BPS), bisphenol AF (BPAF), and the recently developed tetramethyl bisphenol F (TMBPF; the monomer of valPure V70). Here, we used adult female rat adipose-derived stem cells (rASCs) and human mesenchymal stem cells (hMSCs) to compare the toxicities and potencies of these BPA alternatives in vitro. Rat and human stem cells were exposed to BPA (1-10 µM), 17ß-estradiol (E2; 10 µM), BPS (1-100 µM), BPAF (3×10-4-30 µM), TMBPF (0.01-50 µM), or control media alone (with 0.01% ethanol) for varying time intervals from 10 min to 24 h. We found significantly decreased cell viability and massive apoptosis in rat and human stem cells treated with each BPA analog, as early as 10 min of exposure, and at low, physiologically relevant doses. BPAF showed extreme cytotoxicity in a dose-dependent manner (LC50 =0.014 µM (rASCs) and 0.009 µM (hMSCs)), whereas TMBPF showed a bimodal response, with low and high concentrations being the most toxic (LC50 =0.88 µM (rASCs) and 0.06 µM (hMSCs)). Activated caspase-6 levels increased in nearly all cells treated with the BPA analogs indicating the majority of cell death was due to caspase-6-mediated apoptosis. These results in both rat and human stem cells underscore the toxicity and potency of these BPA analogs, and establish a rank order of potency of: BPAF>TMBPF>BPA>BPS. Further, these and other recent findings indicate that these newer BPA analogs may be 'regrettable substitutions,' being worse than the original parent compound and lacking proper testing and regulation. This work brings to light the need for further toxicological characterization, better regulation, greater public awareness, and the development of safer, more sustainable chemicals and non-plastic products.

Rationale and design of the African Cardiomyopathy and Myocarditis Registry Program: The IMHOTEP study.

BACKGROUND: Heart failure (HF), the dominant form of cardiovascular disease in Africans, is mainly due to hypertension, rheumatic heart disease and cardiomyopathy. Cardiomyopathies pose a great challenge because of poor prognosis and high prevalence in low- and middle-income countries (LMICs). Little is known about the etiology and outcome of cardiomyopathy in Africa. Specifically, the role of myocarditis and the genetic causes of cardiomyopathy are largely unidentified in Africans. METHOD: The African Cardiomyopathy and Myocarditis Registry Program (the IMHOTEP study) is a pan-African multi-centre, hospital-based cohort study, designed with the primary aim of describing the clinical characteristics, genetic causes, prevalence, management and outcome of cardiomyopathy and myocarditis in children and adults. The secondary aim is to identify barriers to the implementation of evidence-based care and provide a platform for trials and other intervention studies to reduce morbidity and mortality in cardiomyopathy. The registry consists of a prospective cohort of newly diagnosed (i.e., incident) cases and a retrospective (i.e., prevalent) cohort of existing cases from participating centres. Patients with cardiomyopathy and myocarditis will be subjected to a standardized 3-stage diagnostic process. To date, 750 patients have been recruited into the multi-centre pilot phase of the study. CONCLUSION: The IMHOTEP study will provide comprehensive and novel data on clinical features, genetic causes, prevalence and outcome of African children and adults with all forms of cardiomyopathy and myocarditis in Africa. Based on these findings, appropriate strategies for management and prevention of the cardiomyopathies in LMICs are likely to emerge.

A comparison of AAIR versus DDDR pacing for patients with sinus node dysfunction: a long-term follow-up study.

OBJECTIVES: The aim of the study was to compare the clinical outcomes [atrial fibrillation (AF), atrio-ventricular (AV) block, device sepsis and lead revision] of patients with sinus node dysfunction (SND) between atrial-pacing atrial-sensing inhibited-response rate-adaptive (AAIR) versus dual-chamber rate-adaptive (DDDR) pacing. The choice of AAIR pacing versus DDDR pacing was determined by AV nodal functional testing at implant. METHODS: We conducted a retrospective review of consecutive patients who underwent AAIR and DDDR pacing over a 10-year period. RESULTS: One hundred and sixteen patients required pacing for symptomatic SND. Fifty-four (46.6%) patients received AAIR pacemakers and 62 (53.4%) received DDDR pacemakers based on AV nodal functional testing at implant. Patients who had AV Wenkebach with atrial pacing at 120 beats per minute received DDDR pacing. Overall the mean age of patients with SND was 65 years and 66.4% were females, 30% were diabetics and 71% were hypertensives. Pre-syncope/syncope (84%) and dizziness (69%) were the most common symptoms. Sinus pauses and sinus bradycardia were the most common ECG manifestations. Over a median follow up of five (IQR: 2-11) years, four patients (7.4%) developed AF in the AAIR group compared to three (4.8%) in the DDDR group (p = 0.70). AV block occurred in one patient in the AAIR group, who required an upgrade to a DDDR pacemaker. There was no difference in device sepsis or need for lead revision between the two groups. CONCLUSIONS: We found that AV nodal functional testing with atrial pacing at the time of pacemaker implantation was a useful tool to help guide the implanter between AAIR or DDDR pacing. Patients who underwent AAIR pacing had a low risk of AF, AV block or lead revision. In resource-limited settings, AAIR pacing guided by AV nodal functional testing should be considered as an alternative to DDDR pacing.