Keratin 5 basal cells are temporally regulated developmental and tissue repair progenitors in bladder urothelium.

Urothelium forms a distensible yet impermeable barrier, senses and transduces stimuli, and defends the urinary tract from mechanical, chemical, and bacterial injuries. Biochemical and genetic labeling studies support the existence of one or more progenitor populations with the capacity to rapidly regenerate the urothelium following injury, but slow turnover, a low mitotic index, and inconsistent methodologies obscure progenitor identity. The progenitor properties of basal keratin 5 urothelial cells (K5-UCs) have been previously investigated, but those studies focused on embryonic or adult bladder urothelium. Urothelium undergoes desquamation and apoptosis after birth, which requires postnatal proliferation and restoration. Therefore, we mapped the fate of bladder K5-UCs across postnatal development/maturation and following administration of cyclophosphamide to measure homeostatic and reparative progenitor capacities, respectively. In vivo studies demonstrate that basal K5-UCs are age-restricted progenitors in neonates and juveniles, but not in adult mice. Neonatal K5-UCs retain a superior progenitor capacity in vitro, forming larger and more differentiated urothelial organoids than adult K5-UCs. Accordingly, K5-UC transcriptomes are temporally distinct, with enrichment of transcripts associated with cell proliferation and differentiation in neonates. Induction of urothelial proliferation is sufficient to restore adult K5-UC progenitor capacity. Our findings advance the understanding of urothelial progenitors and support a linear model of urothelial formation and regeneration, which may have significant impact on therapeutic development or tissue engineering strategies.NEW & NOTEWORTHY Fate mapping reveals an important linear relationship, whereby bladder basal urothelial cells give rise to intermediate and superficial cells in an age-restricted manner and contribute to tissue repair. Neonatal basal cells reprise their role as superior progenitors in vitro and display distinct transcriptional signatures, which suggest progenitor function is at least partially cell intrinsic. However, the urothelium progenitor niche cannot be overlooked, since FGF7 rescues adult basal cell progenitor function.

Systemic PPMO-mediated dystrophin expression in the Dup2 mouse model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a devastating muscle-wasting disease that arises due to the loss of dystrophin expression, leading to progressive loss of motor and cardiorespiratory function. Four exon-skipping approaches using antisense phosphorodiamidate morpholino oligomers (PMOs) have been approved by the FDA to restore a DMD open reading frame, resulting in expression of a functional but internally deleted dystrophin protein, but in patients with single-exon duplications, exon skipping has the potential to restore full-length dystrophin expression. Cell-penetrating peptide-conjugated PMOs (PPMOs) have demonstrated enhanced cellular uptake and more efficient dystrophin restoration than unconjugated PMOs. In the present study, we demonstrate widespread PPMO-mediated dystrophin restoration in the Dup2 mouse model of exon 2 duplication, representing the most common single-exon duplication among patients with DMD. In this proof-of-concept study, a single intravenous injection of PPMO targeting the exon 2 splice acceptor site induced 45% to 68% exon 2-skipped Dmd transcripts in Dup2 skeletal muscles 15 days post-injection. Muscle dystrophin restoration peaked at 77% to 87% average dystrophin-positive fibers and 41% to 51% of normal signal intensity by immunofluorescence, and 15.7% to 56.8% of normal by western blotting 15 to 30 days after treatment. These findings indicate that PPMO-mediated exon skipping is a promising therapeutic strategy for muscle dystrophin restoration in the context of exon 2 duplications.

Investigation of COVID-19 Misinformation in Arabic on Twitter: Content Analysis.

Background: The COVID-19 pandemic has been occurring concurrently with an infodemic of misinformation about the virus. Spreading primarily on social media, there has been a significant academic effort to understand the English side of this infodemic. However, much less attention has been paid to the Arabic side. Objective: There is an urgent need to examine the scale of Arabic COVID-19 disinformation. This study empirically examines how Arabic speakers use specific hashtags on Twitter to express antivaccine and antipandemic views to uncover trends in their social media usage. By exploring this topic, we aim to fill a gap in the literature that can help understand conspiracies in Arabic around COVID-19. Methods: This study used content analysis to understand how 13 popular Arabic hashtags were used in antivaccine communities. We used Twitter Academic API v2 to search for the hashtags from the beginning of August 1, 2006, until October 10, 2021. After downloading a large data set from Twitter, we identified major categories or topics in the sample data set using emergent coding. Emergent coding was chosen because of its ability to inductively identify the themes that repeatedly emerged from the data set. Then, after revising the coding scheme, we coded the rest of the tweets and examined the results. In the second attempt and with a modified codebook, an acceptable intercoder agreement was reached (Krippendorff α≥.774). Results: In total, we found 476,048 tweets, mostly posted in 2021. First, the topic of infringing on civil liberties (n=483, 41.1%) covers ways that governments have allegedly infringed on civil liberties during the pandemic and unfair restrictions that have been imposed on unvaccinated individuals. Users here focus on topics concerning their civil liberties and freedoms, claiming that governments violated such rights following the pandemic. Notably, users denounce government efforts to force them to take any of the COVID-19 vaccines for different reasons. This was followed by vaccine-related conspiracies (n=476, 40.5%), including a Deep State dictating pandemic policies, mistrusting vaccine efficacy, and discussing unproven treatments. Although users tweeted about a range of different conspiracy theories, mistrusting the vaccine's efficacy, false or exaggerated claims about vaccine risks and vaccine-related diseases, and governments and pharmaceutical companies profiting from vaccines and intentionally risking the general public health appeared the most. Finally, calls for action (n=149, 12.6%) encourage individuals to participate in civil demonstrations. These calls range from protesting to encouraging other users to take action about the vaccine mandate. For each of these categories, we also attempted to trace the logic behind the different categories by exploring different types of conspiracy theories for each category. Conclusions: Based on our findings, we were able to identify 3 prominent topics that were prevalent amongst Arabic speakers on Twitter. These categories focused on violations of civil liberties by governments, conspiracy theories about the vaccines, and calls for action. Our findings also highlight the need for more research to better understand the impact of COVID-19 disinformation on the Arab world.