Distinct roles of Bdnf I and Bdnf IV transcript variant expression in hippocampal neurons.

Brain-derived neurotrophic factor (Bdnf) plays a critical role in brain development, dendritic growth, synaptic plasticity, as well as learning and memory. The rodent Bdnf gene contains nine 5' non-coding exons (I-IXa), which are spliced to a common 3' coding exon (IX). Transcription of individual Bdnf variants, which all encode the same BDNF protein, is initiated at unique promoters upstream of each non-coding exon, enabling precise spatiotemporal and activity-dependent regulation of Bdnf expression. Although prior evidence suggests that Bdnf transcripts containing exon I (Bdnf I) or exon IV (Bdnf IV) are uniquely regulated by neuronal activity, the functional significance of different Bdnf transcript variants remains unclear. To investigate functional roles of activity-dependent Bdnf I and IV transcripts, we used a CRISPR activation system in which catalytically dead Cas9 fused to a transcriptional activator (VPR) is targeted to individual Bdnf promoters with single guide RNAs, resulting in transcript-specific Bdnf upregulation. Bdnf I upregulation is associated with gene expression changes linked to dendritic growth, while Bdnf IV upregulation is associated with genes that regulate protein catabolism. Upregulation of Bdnf I, but not Bdnf IV, increased mushroom spine density, volume, length, and head diameter, and also produced more complex dendritic arbors in cultured rat hippocampal neurons. In contrast, upregulation of Bdnf IV, but not Bdnf I, in the rat hippocampus attenuated contextual fear expression. Our data suggest that while Bdnf I and IV are both activity-dependent, BDNF produced from these promoters may serve unique cellular, synaptic, and behavioral functions.

Epidemiology of COVID-19 Infection in Hospitalized End-Stage Kidney Disease Patients in a Predominantly African-American Population.

BACKGROUND: End-stage kidney disease patients on dialysis are particularly susceptible to COVID-19 infection due to comorbidities, age, and logistic constraints of dialysis making social distancing difficult. We describe our experience with hospitalized dialysis patients with COVID-19 and factors associated with mortality. METHODS: From March 1, 2020, to May 31, 2020, all dialysis patients admitted to 4 Emory Hospitals and tested for COVID-19 were identified. Sociodemographic information and clinical and laboratory data were obtained from the medical record. Death was defined as an in-hospital death or transfer to hospice for end-of-life care. Patients were followed until discharge or death. RESULTS: Sixty-four dialysis patients with COVID-19 were identified. Eighty-four percent were African-American. The median age was 64 years, and 59% were males. Four patients were on peritoneal dialysis, and 60 were on hemodialysis for a median time of 3.8 years, while 31% were obese. Fever (72%), cough (61%), and diarrhea (22%) were the most common symptoms at presentation. Thirty-three percent required admission to intensive care unit, and 23% required mechanical ventilation. The median length of stay was 10 days, while 11 patients (17%) died during hospitalization and 17% were discharged to a temporary rehabilitation facility. Age >65 years (RR 13.7, CI: 1.9-100.7), C-reactive protein >100 mg/dL (RR 8.3, CI: 1.1-60.4), peak D-dimer >3,000 ng/mL (RR 4.3, CI: 1.03-18.2), bilirubin >1 mg/dL (RR 3.9, CI: 1.5-10.4), and history of peripheral vascular disease (RR 3.2, CI: 1.2-9.1) were associated with mortality. Dialysis COVID-19-infected patients were more likely to develop thromboembolic complications than those without COVID-19 (RR 3.7, CI: 1.3-10.1). CONCLUSION: In a predominantly African-American population, the mortality of end-stage kidney disease patients admitted with COVID-19 infection was 17%. Age, C-reactive protein, D-dimer, bilirubin, and history of peripheral vascular disease were associated with worse survival.

Distinct roles of Bdnf I and Bdnf IV transcript variant expression in hippocampal neurons.

Brain-derived neurotrophic factor (Bdnf) plays a critical role in brain development, dendritic growth, synaptic plasticity, as well as learning and memory. The rodent Bdnf gene contains nine 5' non-coding exons (I-IXa), which are spliced to a common 3' coding exon (IX). Transcription of individual Bdnf variants, which all encode the same BDNF protein, is initiated at unique promoters upstream of each non-coding exon, enabling precise spatiotemporal and activity-dependent regulation of Bdnf expression. Although prior evidence suggests that Bdnf transcripts containing exon I (Bdnf I) or exon IV (Bdnf IV) are uniquely regulated by neuronal activity, the functional significance of different Bdnf transcript variants remains unclear. To investigate functional roles of activity-dependent Bdnf I and IV transcripts, we used a CRISPR activation (CRISPRa) system in which catalytically-dead Cas9 (dCas9) fused to a transcriptional activator (VPR) is targeted to individual Bdnf promoters with single guide RNAs (sgRNAs), resulting in transcript-specific Bdnf upregulation. Bdnf I upregulation is associated with gene expression changes linked to dendritic growth, while Bdnf IV upregulation is associated with genes that regulate protein catabolism. Upregulation of Bdnf I, but not Bdnf IV, increased mushroom spine density, volume, length, and head diameter, and also produced more complex dendritic arbors in cultured rat hippocampal neurons. In contrast, upregulation of Bdnf IV, but not Bdnf I, in the rat hippocampus attenuated contextual fear expression. Our data suggest that while Bdnf I and IV are both activity-dependent, BDNF produced from these promoters may serve unique cellular, synaptic, and behavioral functions.

Managing COVID-19-positive Solid Organ Transplant Recipients in the Community: What a Community Healthcare Provider Needs to Know.

BACKGROUND: The current surge of coronavirus 2019 (COVID-19) cases in certain parts of the country has burdened the healthcare system, limiting access to tertiary centers for many. As a result, COVID-19-positive Solid Organ Transplant (SOT) recipients are increasingly being managed by local healthcare providers. It is crucial for community providers to understand disease severity and know if COVID-19-impacted SOT recipients have a different clinical course compared with COVID-19-negative SOT recipients with a similar presentation. METHODS: We conducted a retrospective analysis on SOT recipients suspected to have COVID-19 infection tested during March 14, 2020-April 30, 2020. Patients were followed from time of testing to May 31, 2020. RESULTS: One hundred sixty SOT recipients underwent testing: 22 COVID-19 positive and 138 COVID-19 negative. COVID-19-positive patients were more likely to have rapid progression of symptoms (median 3 vs 6 d, P = 0.002), greater hospitalizations (78% vs 64%, P < 0.017), and need for intensive care unit care (45% vs 17%, P < 0.001) Severe COVID-19 infection was not observed in patients on Belatacept for immunosuppression (30% vs 87%,P = 0.001). COVID- 19 positive patients in the intensive care unit were more likely to have multifocal opacities on radiological imaging in comparison to those admitted to the medical floor (90% vs 11%). Survival probability was similar in both cohorts. CONCLUSION: COVID-19-infected SOT recipients have a propensity for rapid clinical decompensation. Local providers need to be work closely with transplant centers to appropriately triage and manage COVID-19 SOT recipients in the community.