Alternative splicing controls the activity of many proteins important for neuronal excitation, but the signal-transduction pathways that affect spliced isoform expression are not well understood. One particularly interesting system of alternative splicing is exon 21 (E21) of the NMDA receptor 1 (NMDAR1 E21), which controls the trafficking of NMDA receptors to the plasma membrane and is repressed by Ca++/calmodulin-dependent protein kinase (CaMK) IV signaling. Here, we characterize the splicing of NMDAR1 E21. We find that E21 splicing is reversibly repressed by neuronal depolarization, and we identify two RNA elements within the exon that function together to mediate the inducible repression. One of these exonic elements is similar to an intronic CaMK IV–responsive RNA element (CaRRE) originally identified in the 3′ splice site of the BK channel STREX exon, but not previously observed within an exon. The other element is a new RNA motif. Introduction of either of these two motifs, called CaRRE type 1 and CaRRE type 2, into a heterologous constitutive exon can confer CaMK IV–dependent repression on the new exon. Thus, either exonic CaRRE can be sufficient for CaMK IV–induced repression. Single nucleotide scanning mutagenesis defined consensus sequences for these two CaRRE motifs. A genome-wide motif search and subsequent RT-PCR validation identified a group of depolarization-regulated alternative exons carrying CaRRE consensus sequences. Many of these exons are likely to alter neuronal function. Thus, these two RNA elements define a group of co-regulated splicing events that respond to a common stimulus in neurons to alter their activity.

Dieulafoy's lesion (DL) is a persistently wide caliber artery that is observed more frequently at the fifth decade of life in the male population with multiple comorbidities. There are a variety of endoscopic therapies that have been used to treat DL; however, there are no clear guidelines on the best treatment modality. This article systematically reviews the diagnosis, the most commonly reported therapies of DL, and offers a suggested algorithm based upon efficacy of treatment such as initial hemostasis, rebleeding rates, and mortality.

Durlobactam (DUR) is a potent inhibitor of Bla Mab and provides protection of amoxicillin and imipenem against hydrolysis. DUR has intrinsic activity and forms stable acyl-enzyme complexes with Ldt Mab2 and Ldt Mab4 . The ability of DUR to protect amoxicillin and imipenem against Bla Mab and its intrinsic activity along with the dual β-lactam target redundancy can explain the rationale behind the potent activity of this combination.