EGFR-dependent endocytosis of Wnt9a and Fzd9b promotes ß-catenin signaling during hematopoietic stem cell development in zebrafish.

Cell-to-cell communication through secreted Wnt ligands that bind to members of the Frizzled (Fzd) family of transmembrane receptors is critical for development and homeostasis. Wnt9a signals through Fzd9b, the co-receptor LRP5 or LRP6 (LRP5/6), and the epidermal growth factor receptor (EGFR) to promote early proliferation of zebrafish and human hematopoietic stem cells during development. Here, we developed fluorescently labeled, biologically active Wnt9a and Fzd9b fusion proteins to demonstrate that EGFR-dependent endocytosis of the ligand-receptor complex was required for signaling. In human cells, the Wnt9a-Fzd9b complex was rapidly endocytosed and trafficked through early and late endosomes, lysosomes, and the endoplasmic reticulum. Using small-molecule inhibitors and genetic and knockdown approaches, we found that Wnt9a-Fzd9b endocytosis required EGFR-mediated phosphorylation of the Fzd9b tail, caveolin, and the scaffolding protein EGFR protein substrate 15 (EPS15). LRP5/6 and the downstream signaling component AXIN were required for Wnt9a-Fzd9b signaling but not for endocytosis. Knockdown or loss of EPS15 impaired hematopoietic stem cell development in zebrafish. Other Wnt ligands do not require endocytosis for signaling activity, implying that specific modes of endocytosis and trafficking may represent a method by which Wnt-Fzd specificity is established.

Long noncoding RNA GATA2AS influences human erythropoiesis by transcription factor and chromatin landscape modulation.

ABSTRACT: Long noncoding RNAs (lncRNAs) are extensively expressed in eukaryotic cells and have been revealed to be important for regulating cell differentiation. Many lncRNAs have been found to regulate erythroid differentiation in the mouse. However, given the low sequence conservation of lncRNAs between mouse and human, our understanding of lncRNAs in human erythroid differentiation remains incomplete. lncRNAs are often transcribed opposite to protein coding genes and regulate their expression. Here, we characterized a human erythrocyte-expressed lncRNA, GATA2AS, which is transcribed opposite to erythroid transcription regulator GATA2. GATA2AS is a 2080-bp long, primarily nucleus-localized noncoding RNA that is expressed in erythroid progenitor cells and decreases during differentiation. Knockout of GATA2AS in human HUDEP2 erythroid progenitor cells using CRISPR-Cas9 genome editing to remove the transcription start site accelerated erythroid differentiation and dysregulated erythroblast gene expression. We identified GATA2AS as a novel GATA2 and HBG activator. Chromatin isolation by RNA purification showed that GATA2AS binds to thousands of genomic sites and colocalizes at a subset of sites with erythroid transcription factors including LRF and KLF1. RNA pulldown and RNA immunoprecipitation confirmed interaction between GATA2AS and LRF and KLF1. Chromatin immunoprecipitation sequencing (ChIP-seq) showed that knockout of GATA2AS reduces binding of these transcription factors genome wide. Assay for transposase-accessible chromatin sequencing (ATAC-seq) and H3K27ac ChIP-seq showed that GATA2AS is essential to maintain the chromatin regulatory landscape during erythroid differentiation. Knockdown of GATA2AS in human primary CD34+ cells mimicked results in HUDEP2 cells. Overall, our results implicate human-specific lncRNA GATA2AS as a regulator of erythroid differentiation by influencing erythroid transcription factor binding and the chromatin regulatory landscape.

PEGylated nanoparticles interact with macrophages independently of immune response factors and trigger a non-phagocytic, low-inflammatory response.

Poly-ethylene-glycol (PEG)-based nanoparticles (NPs) - including cylindrical micelles (CNPs), spherical micelles (SNPs), and PEGylated liposomes (PLs) - are hypothesized to be cleared in vivo by opsonization followed by liver macrophage phagocytosis. This hypothesis has been used to explain the rapid and significant localization of NPs to the liver after administration into the mammalian vasculature. Here, we show that the opsonization-phagocytosis nexus is not the major factor driving PEG-NP - macrophage interactions. First, mouse and human blood proteins had insignificant affinity for PEG-NPs. Second, PEG-NPs bound macrophages in the absence of serum proteins. Third, lipoproteins blocked PEG-NP binding to macrophages. Because of these findings, we tested the postulate that PEG-NPs bind (apo)lipoprotein receptors. Indeed, PEG-NPs triggered an in vitro macrophage transcription program that was similar to that triggered by lipoproteins and different from that triggered by lipopolysaccharide (LPS) and group A Streptococcus. Unlike LPS and pathogens, PLs did not increase transcripts involved in phagocytosis or inflammation. High-density lipoprotein (HDL) and SNPs triggered remarkably similar mouse bone-marrow-derived macrophage transcription programs. Unlike opsonized pathogens, CNPs, SNPs, and PLs lowered macrophage autophagosome levels and either reduced or did not increase the secretion of key macrophage pro-inflammatory cytokines and chemokines. Thus, the sequential opsonization and phagocytosis process is likely a minor aspect of PEG-NP - macrophage interactions. Instead, PEG-NP interactions with (apo)lipoprotein and scavenger receptors appear to be a strong driving force for PEG-NP - macrophage binding, entry, and downstream effects. We hypothesize that the high presence of these receptors on liver macrophages and on liver sinusoidal endothelial cells is the reason PEG-NPs localize rapidly and strongly to the liver.

Structural and Psychosocial Challenges Among Underserved Patients Receiving Hemodialysis During and Beyond the COVID-19 Pandemic: A Qualitative Study.

Rationale & Objective: Racial and ethnic minority groups in the United States are disproportionately affected by chronic kidney disease and progressive kidney failure and face significantly more socioeconomic and psychosocial challenges. However, how such patients' social environment and stigmatization shape their illness experiences and abilities to cope before and during the coronavirus disease 2019 (COVID-19) pandemic has not been well documented, even as social scientific research predicts these groups' exponential vulnerability. Study Design: Qualitative study using semistructured interviews to elicit individual patient narratives about their personal illness experiences before and during the COVID-19 pandemic, any challenges they faced, and their sources of support. Setting & Participants: Using purposive sampling, we recruited 20 adult patients receiving maintenance hemodialysis from centers affiliated with a safety-net hospital in Boston, Massachusetts. Analytical Approach: Interviews were audiotaped, transcribed, and analyzed using thematic content analysis to identify patients' challenges and supports before and during the pandemic. Results: Of the 20 patients in the study, 9 were women, and 18 self-identified as Black or African American. Three main themes emerged, whereby most patients described: (1) stigma and stigmatization as a central element of their life experience; (2) the pandemic as a difficult experience but not a complete rupture from their prepandemic life; and (3) social networks, particularly family, friends, and religious communities, as sources of support crucial to coping with their debilitating illness. Limitations: Whether the findings apply to other settings is unknown, as participants were recruited from centers in a single safety-net urban hospital setting. Conclusions: Psychosocial and environmental factors, including institutional racism and stigmatization, play significant roles in amplifying the burdens shouldered by racial and ethnic minority individuals with kidney disease who now also face the COVID-19 pandemic that has since turned endemic. The results of this study can inform the development of policy interventions aimed at alleviating tensions and structural conditions that impinge on kidney disease patients' wellbeing and health outcomes. Plain-Language Summary: Members of racial and ethnic minority groups in the United States experience the highest rates of progressive kidney failure and face significantly more socioeconomic and psychosocial challenges. We interviewed 20 patients who receive maintenance hemodialysis treatment from centers affiliated with a safety-net hospital. Patients described stigmatization as a central element of their life experience and the pandemic as a difficult challenge (but not a complete rupture) that added to their struggles with illness-related, race-related, and class-related stigmas. Social networks, particularly family, friends, and religious communities, are key sources of support crucial to coping with illness. Findings from this study can inform health care providers and community workers and guide the development of policy interventions to provide better support for these patients.

Effect of experimentally introduced interaural frequency mismatch on sentence recognition in bilateral cochlear-implant listeners.

Bilateral cochlear-implant users experience interaural frequency mismatch because of asymmetries in array insertion and frequency-to-electrode assignment. To explore the acute perceptual consequences of such mismatch, sentence recognition in quiet was measured in nine bilateral cochlear-implant listeners as frequency allocations in the poorer ear were shifted by ±1.5, ±3, and ±4.5 mm using experimental programs. Shifts in frequency allocation >3 mm reduced bilateral sentence scores below those for the better ear alone, suggesting that the poorer ear interfered with better-ear perception. This was not a result of fewer active channels; deactivating electrodes without frequency shifting had minimal effect.

Obesity and inflammation influence pharmacokinetic profiles of PEG-based nanoparticles.

Most patients that will be treated with soft nanoparticles (NPs) will be obese. Yet, NP testing, which begins with pharmacokinetic (PK) and toxicity studies, is carried out almost exclusively in lean rodents having healthy livers and low inflammation. To address this knowledge gap, we determined the PK and toxicity of tail-vein-injected, PEG-based cylindrical nanoparticles (CNPs) and PEGylated liposomes (PLs) as a function of obesity, liver health, and inflammation in leptin-deficient ob/ob and wild-type C57BL/6 J mice. CNPs localized faster to obese livers than to healthy livers within 24 h of injection. PLs localized faster to obese livers than to healthy livers but only 30 min post-injection. Afterwards PL localization to lean livers was higher than localization to obese livers. Overall, PL liver signal peaked ∼6 h post-injection in lean mice, ∼24 h post-injection in heavy mice, and âˆ¼ 48 h post-injection in obese mice. CNPs and PLs were non-toxic to mouse livers as assessed by histology; they reduced many cytokine and chemokine levels that were elevated by obesity. Liver macrophage depletion reduced CNP and PL liver localization as expected; liver sinusoidal endothelial cell (LSEC) depletion reduced PL liver localization but surprisingly increased CNP liver localization. The intensity of RAW264.7 macrophages was higher after CNP incubations than with PL incubations; conversely, the intensity of LSECs was higher after PL incubations than with CNP incubations. This shows the potential for key differences in NP-liver interactions. Triggering inflammation by administering lipopolysaccharide (LPS) to mice increased CNP liver localization but decreased PL liver localization. The results show that obesity and inflammation in a mouse model and in vitro affect soft PEG-based NP interaction with macrophages and LSECs, but also that these NPs can reduce pro-inflammatory pathways increased by obesity.

Effect of experimentally introduced interaural frequency mismatch on sentence recognition in bilateral cochlear-implant listeners.

Bilateral cochlear-implant users experience interaural frequency mismatch because of asymmetries in array insertion and frequency-to-electrode assignment. To explore the acute perceptual consequences of such mismatch, sentence recognition in quiet was measured in nine bilateral cochlear-implant listeners as frequency allocations in the poorer ear were shifted by ±1.5, ±3 and ±4.5 mm using experimental programs. Shifts in frequency allocation >3 mm were found to reduce bilateral sentence scores below those for the better ear alone, suggesting that the poorer ear interfered with better-ear perception. This was not a result of fewer active channels; deactivating electrodes without frequency shifting had minimal effect.

Assessment of Risk Factors, Prehospital Measures and Clinical Needs of Patients Admitted With Snake Envenomation at a Rural Hospital in Trinidad and Tobago.

OBJECTIVE: This study assessed the risk factors for sustaining a snake bite, the prehospital measures employed, and the clinical needs of patients admitted with confirmed envenomation. METHODOLOGY: Data was collected at a single center, a rural secondary care hospital in Trinidad and Tobago. A cross-sectional method was used that enrolled all consenting patients requiring admission following clinical confirmation of snake envenomation during the period 2017-2019. Data collection involved a review of the patient record from the emergency room and hospital admission to establish the clinical need during the time of admission which was defined as the administration of medication, need for surgery, and critical care intervention. Data collection also involved a patient interview to establish demographics, prehospital measures employed, and assessment of the risk factors associated with sustaining the snake bite. RESULTS: 29 patients were admitted for snakebite envenomation during 2017-2019 and all patients consented to enrolment. Of these patients, 22 were male and most commonly were within the age range of 18-40 years old. 34.5% of patients were farmers and 68.9% of patients identified being bitten by the Mapepire Balsain snake. 65.5% of patients reported being unaware of the risk of snake bites and 82.8% were not wearing boots, with the lower limb being the most common bite site among 55.2%. 41.4% of bites were sustained during work-related activity while 34.5% of bites were sustained during recreational activity. Prehospital measures were employed by 18 of the 29 patients with the most common types being irrigation (10.3%), cutting (6.9%), tourniquets (44.8%), pressure immobilization (6.9%), topical applications (3.4%), and ingestion of a substance (6.9%). 34.5% received hospital care within 1 hour of the bite while 55.2% arrived at the hospital between 1 and 4 hours of being bitten. The clinical challenges of these patients included local reactions (82.8%), coagulopathy (72.4%), compartment syndrome (17.2%), cellulitis (3.4%), and dislocated shoulder (3.4%). The clinical needs of these patients included vitamin K (13.8%), antibiotics (93.1%), tetanus shots (17.2%), analgesia (6.8%), and anti-venom (82.7%). 10.3% of patients required debridement and 3.4% required a fasciotomy. The average stay in the hospital was 3.8 days. There were no documents of deaths or need for critical care. CONCLUSION: Persons are most likely to be envenomated by the M. Balsain in Trinidad. These patients are commonly males ranging anywhere from 18 to 40 years presenting local reactions and coagulopathy needing admittance to the hospital. While the majority of patients requiring admission performed some type of prehospital measure, very few did so with pressure immobilization. Furthermore, the majority of patients had a prolonged time before presenting to the hospital; this is a potential area for improvement in the health system through education and sensitization. There was a significant utilization of resources on these patients when taking into consideration their clinical needs, medication, and hospital stay; primary prevention should be a focus through the education of groups who are at higher risk for a venomous snake encounter.

Evaluating Shifts in Perception After a Pilot Trauma Quality Improvement Training Course in Cameroon.

INTRODUCTION: Trauma is a major contributor to the global burden of disease, with low- and middle-income countries (LMICs) being disproportionately affected. Trauma Quality Improvement (QI) initiatives could potentially save an estimated two million lives each year. Successful trauma QI initiatives rely on adequate training and a culture of quality among hospital staff. This study evaluated the effect of a pilot trauma QI training course on participants' perceptions on leadership, medical errors, and the QI process in Cameroon. METHODS: Study participants took part in a three-day, eight-module course training on trauma QI methods and applications. Perceptions on leadership, medical errors, and QI were assessed pre and post-course using a 15-item survey measured on a five-point Likert scale. Median pre- and post-course scores were compared using the Wilcoxon signed-rank test. Knowledge retention and course satisfaction were also evaluated in a post-course survey and evaluation. RESULTS: A majority of the 25 course participants completed pre-course (92%) and post-course (80%) surveys. Participants' perceptions of safety and comfort discussing medical errors at work significantly increased post-course (pre-median = 5, IQR [4-5]; post-median = 5, IQR [5-5]; P = 0.046). The belief that individuals responsible for medical error should be held accountable significantly decreased after the course (pre-median = 3, IQR [2-4]; post-median = 1, IQR [1-2]; P < 0.001). Overall satisfaction with the course was high with median scores ≥4. CONCLUSIONS: These initial results suggest that targeted trauma QI training effectively influences attitudes about QI. Further investigation of the effect of the trauma QI training on hospital staff in larger courses is warranted to assess reproducibility of these findings.

Efficacy of a Bariatric Surgery Clinic-Based Pharmacist.

PURPOSE: To evaluate the impact of a bariatric clinic-based pharmacist on inpatient length of stay, medication errors, and patient experience. MATERIALS AND METHODS: This was a retrospective cohort study comparing patients who received a pre-operative pharmacist consultation to historical cases without pre-operative pharmacist consultation prior to admission for bariatric surgery. A patient experience survey was administered post-operatively to the intervention group. The primary outcome was hospital length of stay (LOS). Secondary outcomes included corrected medication errors on reconciliation, pharmacist interventions, adverse drug event (ADE) prevention, and patient satisfaction. RESULTS: With 68 patients in the intervention group and 67 patients in the control group, the majority were female (76%) and received either laparoscopic Roux-en-Y gastric bypass (53%) or sleeve gastrectomy (47%). The median LOS in the intervention group was 55.5 h, which did not significantly differ from the median 57.9 h in the control group (p = 0.56). The clinic-based pharmacist made an average of 13 interventions per patient. Surveys were distributed to 73 patients with a 60% response rate. High overall satisfaction with the pre-operative pharmacist consultation was reported by 97% of patients. CONCLUSION: Although hospital LOS did not significantly differ between groups, pre-operative pharmacist consultation prevented potential ADEs, and provided strong patient satisfaction. Having pharmacists as part of a multidisciplinary approach to bariatric surgery patient care can prevent medication-related adverse events and improve patient satisfaction.

Pharmacologic induction of PGC-1α stimulates fetal haemoglobin gene expression.

Sickle cell disease (SCD) is a genetic disorder that affects millions around the world. Enhancement of fetal γ-globin levels and fetal haemoglobin (HbF) production in SCD patients leads to diminished severity of many clinical features of the disease. We recently identified the transcriptional co-activator PGC-1α as a new protein involved in the regulation of the globin genes. Here, we report that upregulation of PGC-1α by infection with a lentivirus expressing PGC-1α or by the small-molecule PGC-1α agonist ZLN005 in human primary erythroid progenitor CD34+ cells induces both fetal γ-globin mRNA and protein expression as well as the percentage of HbF-positive cell (F cells) without significantly affecting cell proliferation and differentiation. We further found that the combination of ZLN005 and hydroxyurea (hydroxycarbamide) exhibited an additive effect on the expression of γ-globin and the generation of F cells from cultured CD34+ cells. In addition, ZLN005 induced robust expression of the murine embryonic ßh1-globin gene and to a lesser extent, human γ-globin gene expression in sickle mice. These findings suggest that activation of PGC-1α by ZLN005 might provide a new path for modulating HbF levels with potential therapeutic benefit in ß-hemoglobinopathies.

Antiretroviral Therapy Efficacy Post-Bariatric Weight Loss Surgery: A Case Series of Persons Living with Human Immunodeficiency Virus.

PURPOSE: Human immunodeficiency virus (HIV)-related mortality has decreased secondary to advances in antiretroviral therapy (ART), and the incidence of obesity in this population is increasing. Bariatric surgery is an effective method of weight loss, though changes in the gastrointestinal tract may affect ART absorption and virologic suppression. Existing data are limited to case reports studying outdated therapeutic regimens; studies evaluating modern ART regimens are needed. The objective of this study was to determine if undergoing bariatric surgery impacts HIV virologic failure rate at 12 months post-surgery and to characterize the failure population. MATERIALS AND METHODS: This retrospective case series included adults with virologically suppressed HIV on ART who underwent roux-en-y gastric bypass (RYGB) or sleeve gastrectomy (SG) surgery between 2000 and 2019 (n=20) at one of three medical centers within one academic medical system. The primary outcome was proportion of patients with ART failure at 12 months post-surgery. Select additional data collected included CD4+ count, metabolic parameters, postoperative complications, and medication non-adherence. RESULTS: A total of 18 patients were included in this analysis. Seventeen of 18 patients (94%) maintained virologic suppression within 12 months post-surgery. There were no significant changes in CD4+ counts before and after surgery. The one failure was an African American woman who underwent sleeve gastrectomy surgery. This patient's baseline viral load was undetectable and CD4+ count was 263 cells/mm3. CONCLUSION: Undergoing bariatric surgery did not increase virologic failure rate in a small cohort of persons living with HIV, and ART non-adherence was associated with virologic failure.

Presence of hearing loss is predictive of return for further stages of tinnitus therapy following initial education and counseling.

OBJECTIVE: Identify clinical factors that predict the likelihood of patients returning for further evaluation and treatment following stage 1 education and counselling in a staged tinnitus habituation program. DESIGN: Retrospective cross-sectional study. Demographics, audiometric findings and Tinnitus Handicap Inventory (THI) scores were used for predictive modelling to determine the likelihood of patients returning for subsequent therapy. STUDY SAMPLES: One hundred and ninety consecutive patients treated in an outpatient, staged tinnitus habituation program. RESULTS: Improvements in THI scores were observed in all subjects (n = 119, d = 0.49, p < 0.001), both for those without hearing loss (n = 13, d = 0.54, p = 0.03) and those with hearing loss (n = 106, d = 0.48, p < 0.001) following Stage 1 education and counselling. Subjects with hearing loss were 14 times more likely to return for Stage 2 evaluation (p < 0.001) following completion of Stage 1 education and counselling. CONCLUSION: Subjects with idiopathic subjective non-pulsatile tinnitus across all degrees of tinnitus severity benefit from group education and counselling alone. Subjects with hearing loss, irrespective of most hearing loss configurations, are more likely to return for subsequent stages of the program.

Identifying Perceived Barriers to Human Papillomavirus Vaccination as a Preventative Strategy for Cervical Cancer in Nigeria.

Background: Cervical cancer deaths are disproportionately higher in developing countries depicting one of the most profound health disparities existing today and is ranked as the second most frequent cancer among women in Nigeria. The Human Papillomavirus (HPV) vaccine as a primary prevention strategy is not widely used in Nigeria. This study investigated perceived barriers to HPV vaccination in a Nigerian community, targeting health workers' perceptions. Methods: This descriptive study captured responses from a cross-sectional, convenience sample of adult health workers within Anambra State, Nigeria. An anonymous 42-item survey with multiple validated scales was developed based on the Theory of Planned Behavior model and previous studies. The self-administered survey was distributed by research assistants at study sites within Anambra State which were identified through local constituents by the regional zones Adazi-Ani, Onitsha, and Awka. Data analyses were performed using Microsoft Excel for descriptive statistics and R software for the logistic regression, with a statistical significance level of 5%. Subgroup analysis was performed for the baseline knowledge questionnaire to determine if there were any differences in correct responses based on demographics such as: Institution type, profession, age, sex, religion and parental status. Results: Responses were collected from 137 Nigerian health workers; 44% nurses, 14% physicians, 6% pharmacists and 31% other health workers. The majority of respondents were female (69%), between 18 and 39 years of age (78%), from urban settings (82%), and identified as having Christian religious beliefs (97%). The most significant barriers identified were lack of awareness (39%), vaccine availability (39%), and cost (13%). When asked baseline knowledge questions regarding HPV, females were more likely to answer incorrectly as compared to males. Significant differences were found for statements: (1) HPV is sexually transmitted (p = 0.008) and (2) HPV is an infection that only affects women (p = 0.004). Conclusions: Perceived barriers to HPV vaccination identified by Nigerian health workers include lack of awareness, vaccine availability/accessibility, cost, and concerns about acceptability. Ongoing efforts to subsidize vaccine costs, campaigns to increase awareness of HPV vaccine, and interventions to improve attainability could advance administration rates in Nigeria, and ultimately improve death rates due to cervical cancer in this population.

Enhanced Stromal Cell CBS-H2S Production Promotes Estrogen-Stimulated Human Endometrial Angiogenesis.

Angiogenesis is a physiological process for endometrial regeneration in the menstrual cycle and remodeling during pregnancy. Endogenous hydrogen sulfide (H2S), produced by cystathionine-ß synthase (CBS) and cystathionine-γ lyase (CSE), is a potent proangiogenic factor; yet, whether the H2S system is expressed in the endometrium and whether H2S plays a role in endometrial angiogenesis are unknown. This study was to test whether estrogens stimulate endometrial H2S biosynthesis to promote endometrial microvascular endothelial cell (EMEC) angiogenesis. CBS messenger RNA/protein and H2S production significantly differed among endometria from postmenopausal (POM), premenopausal secretory (sPRM), and proliferative (pPRM) nonpregnant (NP) and pregnant (Preg) women (P < .05) in a rank order of POM approximately equal to sPRM is less than pPRM is less than Preg, positively correlating with angiogenesis indices and endogenous estrogens and with no difference in CSE expression. CBS and CSE proteins were localized to stroma, glands, and vessels in endometrium, and greater stromal CBS protein was observed in the pPRM and Preg states. Estradiol-17ß (E2) (but not progesterone) stimulated CBS (but not CSE) expression and H2S production in pPRM endometrial stromal cells (ESCs) in vitro, which were attenuated by ICI 182 780. The H2S donor sodium hydrosulfide promoted in vitro EMEC angiogenesis. Co-culture with sPRM, pPRM, and Preg ESCs all stimulated EMEC migration with a rank order of sPRM less than pPRM approximately equal to Preg. CBS (but not CSE) inhibition attenuated ESC-stimulated EMEC migration. E2 did not affect EMEC migration but potentiated ESC-stimulated EMEC migration. Altogether, estrogens stimulate specific receptor-dependent stromal CBS-H2S production to promote endometrial EMEC angiogenesis in women.

Baseline Patient Safety Culture in Cameroon: Setting a Foundation for Trauma Quality Improvement.

BACKGROUND: Trauma quality improvement (QI) has resulted in decreased trauma mortality and morbidity in high-income countries and has the potential to do the same in low- and middle-income countries. Effective implementation of QI programs relies on a foundational culture of patient safety; however, studies on trauma-related patient safety culture in Sub-Saharan Africa remain scarce. This study assesses baseline patient safety culture in Cameroon to best identify opportunities for improvement. MATERIALS AND METHODS: Over a 3-week period, the Hospital Survey on Patient Safety Culture was administered in three hospitals in the Littoral region of Cameroon. Percentages of positive responses (PPRs) were calculated across 42 items in 12 survey dimensions. A mixed-effects logistic regression model was used to summarize dimension-level percentages and confidence intervals. RESULTS: A total of 179 trauma-related hospital personnel were surveyed with an overall response rate of 76.8%. High PPRs indicate favorable patient safety culture. Of the 12 dimensions evaluated by the Hospital Survey on Patient Safety Culture, nine had a PPR below 50%. Dimensions particularly pertinent in the context of QI include Nonpunitive Response to Errors with a PPR of 25.8% and Organization Learning-Continuous Improvement with a PPR of 64.7%. CONCLUSIONS: The present study elucidates an opportunity for the development of trauma patient safety culture in Cameroon. Low PPR for Nonpunitive Response to Errors indicates a need to shift cultural paradigms from ascribing individual blame to addressing systemic shortcomings of patient care. Moving forward, data from this study will inform interventions to cultivate patient safety culture in partnering Cameroonian hospitals.

Proarrhythmic Electrical Remodeling by Noncardiomyocytes at Interfaces With Cardiomyocytes Under Oxidative Stress.

Life-threatening ventricular arrhythmias, typically arising from interfaces between fibrosis and surviving cardiomyocytes, are feared sequelae of structurally remodeled hearts under oxidative stress. Incomplete understanding of the proarrhythmic electrical remodeling by fibrosis limits the development of novel antiarrhythmic strategies. To define the mechanistic determinants of the proarrhythmia in electrical crosstalk between cardiomyocytes and noncardiomyocytes, we developed a novel in vitro model of interface between neonatal rat ventricular cardiomyocytes (NRVMs) and controls [NRVMs or connexin43 (Cx43)-deficient HeLa cells] vs. Cx43+ noncardiomyocytes [aged rat ventricular myofibroblasts (ARVFs) or HeLaCx43 cells]. We performed high-speed voltage-sensitive optical imaging at baseline and following acute H2O2 exposure. In NRVM-NRVM and NRVM-HeLa controls, no arrhythmias occurred under either experimental condition. In the NRVM-ARVF and NRVM-HeLaCx43 groups, Cx43+ noncardiomyocytes enabled passive decremental propagation of electrical impulses and impaired NRVM activation and repolarization, thereby slowing conduction and prolonging action potential duration. Following H2O2 exposure, arrhythmia triggers, automaticity, and non-reentrant and reentrant arrhythmias emerged. This study reveals that myofibroblasts (which generate cardiac fibrosis) and other noncardiomyocytes can induce not only structural remodeling but also electrical remodeling and that electrical remodeling by noncardiomyocytes can be particularly arrhythmogenic in the presence of an oxidative burst. Synergistic electrical remodeling between H2O2 and noncardiomyocytes may account for the clinical arrhythmogenicity of myofibroblasts at fibrotic interfaces with cardiomyocytes in ischemic/non-ischemic cardiomyopathies. Understanding the enhanced arrhythmogenicity of synergistic electrical remodeling by H2O2 and noncardiomyocytes may guide novel safe-by-design antiarrhythmic strategies for next-generation iatrogenic interfaces between surviving native cardiomyocytes and exogenous stem cells or engineered tissues in cardiac regenerative therapies.

Effect of Stimulation Rate on Speech Understanding in Older Cochlear-Implant Users.

OBJECTIVES: Cochlear implants (CIs) are considered a safe and effective intervention for more severe degrees of hearing loss in adults of all ages. Although older CI users ≥65 years of age can obtain large benefits in speech understanding from a CI, there is a growing body of literature suggesting that older CI users may not perform as well as younger CI users. One reason for this potential age-related limitation could be that default CI stimulation settings are not optimal for older CI users. The goal of this study was to determine whether improvements in speech understanding were possible when CI users were programmed with nondefault stimulation rates and to determine whether lower-than-default stimulation rates improved older CI users' speech understanding. DESIGN: Sentence recognition was measured acutely using different stimulation rates in 37 CI users ranging in age from 22 to 87 years. Maps were created using rates of 500, 720, 900, and 1200 pulses per second (pps) for each subject. An additional map using a rate higher than 1200 pps was also created for individuals who used a higher rate in their clinical processors. Thus, the clinical rate of each subject was also tested, including non-default rates above 1200 pps for Cochlear users and higher rates consistent with the manufacturer defaults for subjects implanted with Advanced Bionics and Med-El devices. Speech understanding performance was evaluated at each stimulation rate using AzBio and Perceptually Robust English Sentence Test Open-set (PRESTO) sentence materials tested in quiet and in noise. RESULTS: For Cochlear-brand users, speech understanding performance using non-default rates was slightly poorer when compared with the default rate (900 pps). However, this effect was offset somewhat by age, in which older subjects were able to maintain comparable performance using a 500-pps map compared with the default rate map when listening to the more difficult PRESTO sentence material. Advanced Bionics and Med-El users showed modest improvements in their overall performance using 720 pps compared with the default rate (>1200 pps). On the individual-subject level, 10 subjects (11 ears) showed a significant effect of stimulation rate, with 8 of those ears performing best with a lower-than-default rate. CONCLUSIONS: Results suggest that default stimulation rates are likely sufficient for many CI users, but some CI users at any age can benefit from a lower-than-default rate. Future work that provides experience with novel rates in everyday life has the potential to identify more individuals whose performance could be improved with changes to stimulation rate.

EGFR is required for Wnt9a-Fzd9b signalling specificity in haematopoietic stem cells.

Wnt signalling drives many processes in development, homeostasis and disease; however, the role and mechanism of individual ligand-receptor (Wnt-Frizzled (Fzd)) interactions in specific biological processes remain poorly understood. Wnt9a is specifically required for the amplification of blood progenitor cells during development. Using genetic studies in zebrafish and human embryonic stem cells, paired with in vitro cell biology and biochemistry, we determined that Wnt9a signals specifically through Fzd9b to elicit ß-catenin-dependent Wnt signalling that regulates haematopoietic stem and progenitor cell emergence. We demonstrate that the epidermal growth factor receptor (EGFR) is required as a cofactor for Wnt9a-Fzd9b signalling. EGFR-mediated phosphorylation of one tyrosine residue on the Fzd9b intracellular tail in response to Wnt9a promotes internalization of the Wnt9a-Fzd9b-LRP signalosome and subsequent signal transduction. These findings provide mechanistic insights for specific Wnt-Fzd signals, which will be crucial for specific therapeutic targeting and regenerative medicine.