In eye development, inhibition by Notch activity is restricted to specific phases of proneural gene expression, beginning when prepattern decays and is replaced by autoregulation. We suggest that Notch signalling inhibits atonal autoregulation, but not expression by other mechanisms, and that a transition from prepattern to autoregulation is necessary for patterning neural cell determination. Distinct neural tissues might differ in their proneural prepatterns, but use Notch in a similar mechanism.

Dominant Ellipse mutant alleles of the Drosophila EGF receptor homologue (DER) dramatically suppress ommatidium development in the eye and induce ectopic vein development in the wing. Their phenotype suggests a possible role for DER in specifying the founder R8 photoreceptor cells for each ommatidium. Here we analyze the basis of Ellipse mutations and use them to probe the role of DER in eye development. We show that Elp mutations result from a single amino acid substitution in the kinase domain which activates tyrosine kinase activity and MAP kinase activation in tissue culture cells. Transformant studies confirmed that the mutation is hypermorphic in vivo, but the DER function was elevated less than by ectopic expression of the ligand spitz. Ectopic spi promoted photoreceptor differentiation, even in the absence of R8 cells. Pathways downstream of DER activation were assessed to explore the basis of these distinct outcomes. Elp mutations caused overexpression of the Notch target gene E(spl) mdelta and required function of Notch to suppress ommatidium formation. The Elp phenotype also depended on the secreted protein argos and was reverted in Elp aos double mutants. Complete loss of DER function in clones of null mutant cells led to delay in R8 specification and subsequently to loss of mutant cells. The DER null phenotype was distinct from that of either spitz or vein mutants, suggesting that a combination of these or other ligands was required for aspects of DER function. In normal development DER protein was expressed in most retinal cells, but at distinct levels. We used an antibody specific for diphospho-ERK as well as expression of the DER target gene argos to assess the pattern of DER activity, finding highest activity in the intermediate groups of cells in the morphogenetic furrow. However, studies of mutant genotypes suggested that this activity may not be required for normal ommatidium development. Since we saw distinct phenotypic effects of four different levels of DER activity associated with wild-type, null mutant, Elp mutant, or fully activated DER function, we propose that multiple thresholds separate several aspects of DER function. These include activation of N signaling to repress R8 specification, turning on argos expression, and recruiting photoreceptors R1-R7. It is possible that during normal eye development these thresholds are attained by different cells, contributing to the pattern of retinal differentiation.

. Notch has sequentially opposite effects on the same cells, by first promoting and then inhibiting proneural gene function. This apparently paradoxical sequence of events has two possible consequences. Firstly, coupling of alternative cellular responses to the same receptor may prevent them from occurring simultaneously. Secondly, consecutive regulatory processes become temporally coupled, so that these events follow on from each other, without gaps or overlaps.

The number of cells in developing organs must be controlled spatially by extracellular signals. Our results show how cell number can be regulated by cell interactions controlling proliferation and survival in local neighborhoods in the case of the Drosophila compound eye. Intercellular signals act during the second mitotic wave, a cell cycle that generates a pool of uncommitted cells used for most ommatidial fates. We find that G1/S progression to start the cell cycle requires EGF receptor inactivity. EGF receptor activation is then required for progression from G2 to M phase of the same cells, and also prevents apoptosis. EGF receptor activation depends on short-range signals from five-cell preclusters of photoreceptor neurons not participating in the second mitotic wave. Through proliferation and survival control, such signals couple the total number of uncommitted cells being generated to the neural patterning of the retina.

Objective.-To evaluate the long-term safety and tolerability of ubrogepant for the acute treatment of migraine. Background.-Ubrogepant is an oral, calcitonin gene-related receptor antagonist in development for the acute treatment of migraine. The efficacy of ubrogepant was demonstrated in 2 phase 3 trials in which a significant improvement was observed in migraine headache pain, migraine-associated symptoms, and ability to function.Methods.-This was a phase 3, multicenter, randomized, open-label, 52-week extension trial. Adults with migraine with or without aura entered the trial after completing one of 2 phase 3 lead-in trials and were re-randomized 1:1:1 to usual care, ubrogepant 50 mg, or ubrogepant 100 mg. Randomization to ubrogepant dose was blinded. Those randomized to usual care continued to treat migraine attacks with their own medication. The usual care arm was included in this trial to capture background rates of hepatic laboratory parameters and contextualize hepatic safety assessments. Safety and tolerability were the primary outcome measures. The safety population for the ubrogepant arms included all randomized participants who received at least 1 dose of treatment. All cases of alanine aminotransferase (ALT)/aspartate aminotransferase (AST) elevations of ≥3 times the upper limit of normal were adjudicated by an independent panel of liver experts who were blinded to dose.Results.-The safety population included 1230 participants (404 in the ubrogepant 50-mg group, 409 in the ubrogepant 100-mg group, and 417 in the usual care group). Participants were on average 42 years of age, 90% (1106/1230) female and 85% (1043/1230) white, with an average BMI of 30 kg/m 2 . Throughout the trial, 21,454 migraine attacks were treated with 31,968 doses of ubrogepant. Treatment-emergent adverse events (TEAEs) were reported by 268/404 (66%) participants receiving ubrogepant 50 mg and 297/409 (73%) receiving ubrogepant 100 mg. The most commonly reported TEAE was upper respiratory tract infection (<12%); findings were similar across dose groups. Treatment-related TEAEs were reported by 42/404 (10%) participants in the ubrogepant 50-mg group and 43/409 (11%) in the ubrogepant 100-mg group. Serious adverse events (SAEs) were reported by 9/404 (2%) participants in the ubrogepant 50-mg group and 12/409 (3%) participants in the ubrogepant 100-mg group. Twenty cases of ALT/AST levels of ≥3 times the upper limit of normal were reported and reviewed by an independent clinical adjudication committee of liver experts. There were no cases of Hy's Law.Conclusions.-Long-term intermittent use of ubrogepant 50 and 100 mg given as 1 or 2 doses per attack for the acute treatment of migraine was safe and well tolerated, as indicated by a low incidence of treatment-related TEAEs and SAEs and discontinuations due to adverse events in this 1-year trial.

It has been suggested that lateral specification of cell fate by Notch signaling depends on feedback on Notch (N) and Delta (Dl) transcription to establish reciprocal distributions of the receptor and its ligand at the protein level. In Drosophila neurogenesis the predicted reciprocal protein distributions have not been observed. Either this model of lateral specification or the description of N and/or Dl protein distributions must be incomplete. We have reexamined R8 photoreceptor specification in the developing eye to resolve this question for this example of lateral specification. N and Dl protein levels were assessed in the cell as a whole and at the cell surface, where these proteins were mostly found at the intercellular cell junctions. Protein levels did not correspond to Notch signaling in wild type. However, Dl transcription and protein levels did correlate with altered N signaling in mutant genotypes. Our findings suggest the difference relates to the speed of lateral specification in vivo. The time required for N signaling to inhibit ato expression was at most 90 min, but changes in the Dl protein distribution in mutant genotypes arose more slowly. N expression was little regulated by N signaling, but protein encoded by the Nts1 allele was temperature-sensitive for appearance at the cell surface. Some aspects of the pattern of Dl protein appeared to be due to endocytosis. We conclude that feedback of N signaling on Dl transcription does occur but is too slow to account for the pattern of R8 specification. Studies of ommatidia mosaic for a Notch duplication, or for the Nts1 allele at semi-restrictive temperatures, found that cells beginning with less N activity were not necessarily predisposed to be selected for R8 differentiation. Our data argue that other signals may be responsible for the pattern of R8 cell fate allocation by N. Potential relevance to other neurogenic regions is discussed.

Objective To evaluate the efficacy of ubrogepant on patient‐reported functional disability, satisfaction with study medication, and global impression of change. Background Ubrogepant is a small‐molecule, oral calcitonin gene‐related peptide receptor antagonist indicated for the acute treatment of migraine. In 2 phase 3 trials (ACHIEVE I and II), ubrogepant demonstrated efficacy vs placebo on the 2 co‐primary endpoints of headache pain freedom and absence of the most bothersome migraine‐associated symptom at 2 hours post dose for the 50 and 100 mg doses. Patient‐reported outcomes, such as functional disability, satisfaction, and patient global impression of change, can provide additional evidence of the efficacy of an acute treatment for migraine on clinically meaningful and patient‐relevant outcomes. Methods ACHIEVE I and ACHIEVE II were multicenter, randomized, double‐blind, placebo‐controlled, parallel‐group, single‐attack trials in adults (18‐75 years) with migraine. In ACHIEVE I, participants were randomized 1:1:1 to placebo or ubrogepant 50 or 100 mg; in ACHIEVE II, participants were randomized 1:1:1 to placebo or ubrogepant 25 or 50 mg to treat a migraine attack with moderate or severe headache pain. Participants rated ability to perform daily activities on the Functional Disability Scale, before dosing and at 1, 2, 4, and 8 hours after the initial dose; satisfaction with study medication at 2 and 24 hours; and impression of overall change in migraine on the Patient Global Impression of Change scale at 2 hours. In prespecified analyses for each trial, each outcome was compared between each ubrogepant dose group and the relevant placebo group. Data were pooled from the ubrogepant 50 mg and placebo groups of the 2 trials in a post hoc analysis. Results In ACHIEVE I, 559 participants were randomized to placebo, 556 to ubrogepant 50 mg, and 557 to ubrogepant 100 mg; in ACHIEVE II, 563 were randomized to placebo, 561 to ubrogepant 25 mg, and 562 to ubrogepant 50 mg. At 2 hours post dose, significantly higher proportions of ubrogepant‐treated participants vs placebo‐treated participants reported being able to function normally (ACHIEVE I: ubrogepant 50 mg, 40.6% [171/421], P = .0012 vs placebo; ubrogepant 100 mg, 42.9% [192/448], P < .0001 vs placebo; placebo, 29.8% [136/456]; ACHIEVE II: ubrogepant 25 mg, 42.6% [185/434], P = .0015 vs placebo; ubrogepant 50 mg, 40.5% [188/464], P = .0118 vs placebo; placebo, 34.2% [156/456]; pooled 50 mg, 40.6% [359/885], vs pooled placebo, 32.0% [292/912]; P < .0001), were satisfied/extremely satisfied with study medication (ACHIEVE I: 50 mg, 36.3% [147/405], P < .0001 vs placebo; 100 mg, 35.8% [149/416], P = .0002 vs placebo; placebo, 24.1% [104/432]; ACHIEVE II: 25 mg, 35.1% [141/402], P = .0018 vs placebo; 50 mg, 37.8% [163/431], P < .0001 vs placebo; placebo, 24.8% [106/427]; pooled ubrogepant 50 mg, 37.1% [310/836], vs pooled placebo, 24.5% [210/859]; P < .0001), and indicated that their migraine was much/very much better on the Patient Global Impression of Change scale (A...

In this study, no difference in the rates of TBV change between the two periods was observed; however, memantine treatment was found to be associated with slowing of right hippocampal atrophy, and with improvement on one test of executive functioning as well as a test of confrontation naming ability. Trials using structural magnetic resonance imaging and a delayed-start design may be a feasible option for the assessment of treatments for AD.