Functionalized dihydrobenzofuran derivatives can be obtained by intramolecular alkoxycyanation and alkoxyacylation of alkenes (see scheme). In both transformations, selective activation of an OFG ...bond is accomplished by using a transition‐metal catalyst. These transformations represent a conceptually new approach to metal‐catalyzed alkene difunctionalization.
Re-expression of the paralogous γ-globin genes (HBG1/2) could be a universal strategy to ameliorate the severe β-globin disorders sickle cell disease (SCD) and β-thalassemia by induction of fetal ...hemoglobin (HbF, α
γ
)
. Previously, we and others have shown that core sequences at the BCL11A erythroid enhancer are required for repression of HbF in adult-stage erythroid cells but are dispensable in non-erythroid cells
. CRISPR-Cas9-mediated gene modification has demonstrated variable efficiency, specificity, and persistence in hematopoietic stem cells (HSCs). Here, we demonstrate that Cas9:sgRNA ribonucleoprotein (RNP)-mediated cleavage within a GATA1 binding site at the +58 BCL11A erythroid enhancer results in highly penetrant disruption of this motif, reduction of BCL11A expression, and induction of fetal γ-globin. We optimize conditions for selection-free on-target editing in patient-derived HSCs as a nearly complete reaction lacking detectable genotoxicity or deleterious impact on stem cell function. HSCs preferentially undergo non-homologous compared with microhomology-mediated end joining repair. Erythroid progeny of edited engrafting SCD HSCs express therapeutic levels of HbF and resist sickling, while those from patients with β-thalassemia show restored globin chain balance. Non-homologous end joining repair-based BCL11A enhancer editing approaching complete allelic disruption in HSCs is a practicable therapeutic strategy to produce durable HbF induction.
Base editing by nucleotide deaminases linked to programmable DNA-binding proteins represents a promising approach to permanently remedy blood disorders, although its application in engrafting ...hematopoietic stem cells (HSCs) remains unexplored. In this study, we purified A3A (N57Q)-BE3 base editor for ribonucleoprotein (RNP) electroporation of human-peripheral-blood-mobilized CD34
hematopoietic stem and progenitor cells (HSPCs). We observed frequent on-target cytosine base edits at the BCL11A erythroid enhancer at +58 with few indels. Fetal hemoglobin (HbF) induction in erythroid progeny after base editing or nuclease editing was similar. A single therapeutic base edit of the BCL11A enhancer prevented sickling and ameliorated globin chain imbalance in erythroid progeny from sickle cell disease and β-thalassemia patient-derived HSPCs, respectively. Moreover, efficient multiplex editing could be achieved with combined disruption of the BCL11A erythroid enhancer and correction of the HBB -28A>G promoter mutation. Finally, base edits could be produced in multilineage-repopulating self-renewing human HSCs with high frequency as assayed in primary and secondary recipient animals resulting in potent HbF induction in vivo. Together, these results demonstrate the potential of RNP base editing of human HSPCs as a feasible alternative to nuclease editing for HSC-targeted therapeutic genome modification.
The enantioselective synthesis of 2-(arylmethyl)- and 2-(alkenylmethyl)pyrrolidine derivatives via Pd-catalyzed alkene carboamination reactions is described. These transformations generate ...enantiomerically enriched products with up to 94% ee from readily available alkenyl or aryl bromides and N-boc-pent-4-enylamines. The application of this method to a concise asymmetric synthesis of (−)-tylophorine is also discussed.
We compare equilibrium climate sensitivity (ECS) estimates from pairs of long (≥ 800‐year) control and abruptly quadrupled CO2 simulations with shorter (150, 300 year) coupled atmosphere‐ocean ...simulations and Slab Ocean Models (SOM). Consistent with previous work, ECS estimates from shorter coupled simulations based on annual averages for years 1‐150 underestimate those from SOM (‐8% ± 13%) and long (‐14% ± 8%) simulations. Analysis of only years 21‐150 improved agreement with SOM (‐2% ± 14%) and long (‐8% ± 10%) estimates. Use of pentadal averages for years 51‐150 results in improved agreement with long simulations (‐4% ± 11%). While ECS estimates from current generation US models based on SOM and coupled annual averages of years 1‐150 range from 2.6°C to 5.3°C, estimates based longer simulations of the same models range from 3.2°C to 7.0°C. Such variations between methods argues for caution in comparison and interpretation of ECS estimates across models.
Noninvasive ventilation (NIV) with a face mask is relatively ineffective at preventing endotracheal intubation in patients with acute respiratory distress syndrome (ARDS). Delivery of NIV with a ...helmet may be a superior strategy for these patients.
To determine whether NIV delivered by helmet improves intubation rate among patients with ARDS.
Single-center randomized clinical trial of 83 patients with ARDS requiring NIV delivered by face mask for at least 8 hours while in the medical intensive care unit at the University of Chicago between October 3, 2012, through September 21, 2015.
Patients were randomly assigned to continue face mask NIV or switch to a helmet for NIV support for a planned enrollment of 206 patients (103 patients per group). The helmet is a transparent hood that covers the entire head of the patient and has a rubber collar neck seal. Early trial termination resulted in 44 patients randomized to the helmet group and 39 to the face mask group.
The primary outcome was the proportion of patients who required endotracheal intubation. Secondary outcomes included 28-day invasive ventilator-free days (ie, days alive without mechanical ventilation), duration of ICU and hospital length of stay, and hospital and 90-day mortality.
Eighty-three patients (45% women; median age, 59 years; median Acute Physiology and Chronic Health Evaluation APACHE II score, 26) were included in the analysis after the trial was stopped early based on predefined criteria for efficacy. The intubation rate was 61.5% (n = 24) for the face mask group and 18.2% (n = 8) for the helmet group (absolute difference, -43.3%; 95% CI, -62.4% to -24.3%; P < .001). The number of ventilator-free days was significantly higher in the helmet group (28 vs 12.5, P < .001). At 90 days, 15 patients (34.1%) in the helmet group died compared with 22 patients (56.4%) in the face mask group (absolute difference, -22.3%; 95% CI, -43.3 to -1.4; P = .02). Adverse events included 3 interface-related skin ulcers for each group (ie, 7.6% in the face mask group had nose ulcers and 6.8% in the helmet group had neck ulcers).
Among patients with ARDS, treatment with helmet NIV resulted in a significant reduction of intubation rates. There was also a statistically significant reduction in 90-day mortality with helmet NIV. Multicenter studies are needed to replicate these findings.
clinicaltrials.gov Identifier: NCT01680783.
Positive water effect: A catalyst composed of Pd2(dba)3 (dba=dibenzylideneacetone) and (S)‐Siphos‐PE is effective for the enantioselective coupling of N‐allyl ureas with aryl bromides to afford ...4‐substituted imidazolidin‐2‐ones. Added water leads to significantly improved enantioselectivities with electron‐poor aryl halide substrates. It is suggested that the CC bond‐forming reductive elimination is the enantiodetermining step in these reactions.
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