Down syndrome (trisomy 21) is the most common genetic cause of intellectual disability, but the precise molecular mechanisms underlying impaired cognition remain unclear. Elucidation of these mechanisms has been hindered by the lack of a model system that contains full trisomy of chromosome 21 (Ts21) in a human genome that enables normal gene regulation. To overcome this limitation, we created Ts21-induced pluripotent stem cells (iPSCs) from two sets of Ts21 human fibroblasts. One of the fibroblast lines had low level mosaicism for Ts21 and yielded Ts21 iPSCs and an isogenic control that is disomic for human chromosome 21 (HSA21). Differentiation of all Ts21 iPSCs yielded similar numbers of neurons expressing markers characteristic of dorsal forebrain neurons that were functionally similar to controls. Expression profiling of Ts21 iPSCs and their neuronal derivatives revealed changes in HSA21 genes consistent with the presence of 50% more genetic material as well as changes in non-HSA21 genes that suggested compensatory responses to oxidative stress. Ts21 neurons displayed reduced synaptic activity, affecting excitatory and inhibitory synapses equally. Thus, Ts21 iPSCs and neurons display unique developmental defects that are consistent with cognitive deficits in individuals with Down syndrome and may enable discovery of the underlying causes of and treatments for this disorder.cerebral cortex | developmental disorders D own syndrome (DS) is the most frequent single cause of human birth defects and intellectual disability (ID) (1). DS is caused by trisomy of chromosome 21 (Ts21) (2), resulting in the triplication of over 400 genes (3-5), which makes elucidation of the precise mechanisms underlying ID in DS a significant challenge. Confounding this difficulty is the relative inaccessibility of human tissue and incomplete human Ts21 in the context of mouse models. Despite these shortcomings, studies using mouse models containing trisomy of parts of syntenic chromosome 21 (HSA21) have put forth several critical hypotheses on the cellular and molecular mechanisms underlying DS features. It is essential, however, to test these hypotheses in human cells with full triplication of HSA21 in a context that allows for normal gene regulation. Here, we used Ts21-induced pluripotent stem cells (iPSCs) to test hypotheses of the underlying causes of ID in DS, with specific regard to neuropathophysiology. ResultsIsogenic Human Ts21 iPSCs. Fibroblasts from two individuals diagnosed with DS were reprogrammed to iPSCs. FISH for HSA21 in one fibroblast line showed mosaicism, where ∼90% of cells carried Ts21, whereas ∼10% were euploid (Fig. 1A). Reprogramming of the mosaic fibroblasts by retrovirus (6) resulted in three viable iPSC clones, two clones that carried Ts21 and one euploid (Fig. 1B). Mosaicism in DS individuals is rare, occurring in ∼1-3% of DS cases (7), but it can also emerge in vitro (8), potentially because of nondisjunction events during cell division.

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and is closely linked with autism. The genetic basis of FXS is an expansion of CGG repeats in the 5¢-untranslated region of the FMR1 gene on the X chromosome leading to the loss of expression of the fragile X mental retardation protein (FMRP). The cause of FXS has been known for over 20 years, yet the full molecular and cellular consequences of this mutation remain unclear. Although mouse and fly models have provided significant understanding of this disorder and its effects on the central nervous system, insight from human studies is limited. We have created human induced pluripotent stem cell (iPSC) lines from fibroblasts obtained from individuals with FXS to enable in vitro modeling of the human disease. Three young boys with FXS who came from a well-characterized cohort representative of the range of affectedness typical for the syndrome were recruited to aid in linking cellular and behavioral phenotypes. The FMR1 mutation is preserved during the reprogramming of patient fibroblasts to iPSCs. Mosaicism of the CGG repeat length in one of the patient's fibroblasts allowed for the generation of isogenic lines with differing CGG repeat lengths from the same patient. FXS forebrain neurons were differentiated from these iPSCs and display defective neurite initiation and extension. These cells provide a well-characterized resource to examine potential neuronal deficits caused by FXS as well as the function of FMRP in human neurons.

SUMMARYHow mutations in glial fibrillary acidic protein (GFAP) cause Alexander disease (AxD) remains elusive. We generated iPSCs from two AxD patients and corrected the GFAP mutations to examine the effects of mutant GFAP on human astrocytes. AxD astrocytes displayed GFAP aggregates, recapitulating the pathological hallmark of AxD. RNA sequencing implicated the endoplasmic reticulum, vesicle regulation, and cellular metabolism. Corroborating this analysis, we observed enlarged and heterogeneous morphology coupled with perinuclear localization of endoplasmic reticulum and lysosomes in AxD astrocytes. Functionally, AxD astrocytes showed impaired extracellular ATP release, which is responsible for attenuated calcium wave propagation. These results reveal that AxD-causing mutations in GFAP disrupt intracellular vesicle regulation and impair astrocyte secretion, resulting in astrocyte dysfunction and AxD pathogenesis.

To maximize the quality of sign-out documents within the internal medicine residency, a quality improvement intervention was developed and implemented. Written sign-outs were collected from general medicine ward teams and graded using an 11-point checklist; in-person feedback was then given directly to the ward teams. Documentation of many of the 11 elements improved: mental status (22% to 66%, P < .0001), decisionality (40% to 66%, P < .0001), lab/test results (63% to 69%, P < .0001), level of acuity (34% to 50%, P < .0001), anticipatory guidance (69% to 82%, P < .0001), and future plans (35% to 38%, P < .0005). The use of vague language declined (41% to 26%, P < .0001). The mean total scores improved from 7.0 to 8.2 out of a possible 11 (P < .0001). As new house staff rotated onto the services, improvement over time was sustained with 1 feedback session per team, per month. Similar interventions could be made in other programs and other institutions.

BACKGROUND: COPD exacerbations lead to accelerated decline in lung function, poor quality of life, and increased mortality and cost. Emergency department (ED) observation units provide short-term care to reduce hospitalizations and cost. Strategies to improve outcomes in ED observation units following COPD exacerbations are needed. We sought to reduce 30-d ED revisits for COPD exacerbations managed in ED observation units through implementation of a COPD care bundle. The study setting was an 800-bed, academic, safety-net hospital with 700 annual ED encounters for COPD exacerbations. Among those discharged from ED observation unit, the 30-d all-cause ED revisit rate (ie, the outcome measure) was 49% (baseline period: August 2014 through September 2016). METHODS: All patients admitted to the ED observation unit with COPD exacerbations were included. A multidisciplinary team implemented the COPD bundle using iterative plan-do-study-act cycles with a goal adherence of 90% (process measure). The bundle, adopted from our inpatient program, was developed using care-delivery failures and unmet subject needs. It included 5 components: appropriate inhaler regimen, 30-d inhaler supply, education on devices available after discharge, standardized discharge instructions, and a scheduled 15-d appointment. We used statistical process-control charts for process and outcome measures. To compare subject characteristics and process features, we sampled consecutive patients from the baseline (n 5 50) and postbundle (n 5 83) period over 5-month and 7-month intervals, respectively. Comparisons were made using t tests and chi-square tests with P < .05 significance. RESULTS: During baseline and postbundle periods, 410 and 165 subjects were admitted to the ED observation unit, respectively. After iterative plan-do-study-act cycles, bundle adherence reached 90% in 6 months, and the 30-d ED revisit rate declined from 49% to 30% (P 5 .003) with a system shift on statistical process-control charts. There was no difference in hospitalization rate from ED observation unit (45% vs 51%, P 5 .16). Subject characteristics were similar in the baseline and postbundle periods. CONCLUSIONS: Reliable adherence to a COPD care bundle reduced 30-d ED revisits among those treated in the ED observation unit.