Leveraging Maker Learning in STEM to Promote Children's Interest in Cancer Research: A Pilot Program.

Children's early awareness about cancer, through exposure to cancer biology and prevention strategies and research principles, is a promising focus of education and learning. It may also benefit the pipeline of people entering into science, technology, engineering, and math (STEM) careers. We describe an educational pilot program for elementary school students, using developmentally appropriate activities focused on cancer at a museum dedicated to children's maker-centered learning and STEM. The program was implemented through a public school in Washington, DC serving students underrepresented in STEM. Program conceptualization, museum and school engagement, and maker learning pedagogy are described, as well as curricular outcomes. A total of N = 111 students (44% female, 75% Black/African American, 5% Latine) participated in a day-long field trip. Museum educators, assisted by cancer center researchers, led a multipart workshop on cancer and the environment and hands-on rotation of activities in microbiology, immunology, and ultraviolet radiation safety; students then completed self-report evaluations. Results indicate that nearly all (> 95%) students practiced activities typical of a STEM professional at the program, and > 70% correctly answered factual questions about topics studied. Importantly, 87-94% demonstrated clear STEM interest, a sense of belonging in the field, and practice implementing skills for success in STEM (e.g., perseverance, imagination, teamwork). This pilot demonstrated acceptability and feasibility in delivering a cancer-focused curriculum to underserved elementary students using maker learning while favorably impacting key objectives. Future scale-up of this program is warranted, with the potential to increase students' motivation to engage in STEM and cancer research.

Prognostic impact of in-stent restenosis in normal weight, overweight, and obese patients undergoing percutaneous coronary intervention.

BACKGROUND: Among patients undergoing percutaneous coronary intervention (PCI), in-stent restenosis (ISR) is related with a worse prognosis, while higher body mass index (BMI) values are associated with better outcomes. It is unclear whether the prognostic impact of ISR varies in function of BMI. METHODS: Patients undergoing PCI at a large center from 2012 to 2019 not presenting with an acute myocardial infarction (MI) were included. Subjects with BMI < 18.5 kg/m2 or treated with bare metal stents were excluded. Patients were stratified according to type of lesion treated (ISR vs. no-ISR) and into four BMI categories: normal weight (BMI 18.5-25 kg/m2 ), overweight (25.0-29.9 kg/m2 ), class I obesity (30.0-34.9 kg/m2 ), class II-III obesity (≥35.0 kg/m2 ). The primary outcome was major adverse cardiovascular events (MACE), a composite of all-cause death, MI, and target vessel revascularization (TVR) at 1 year. RESULTS: Out of 16,234 patients, 3694 (23%) underwent PCI for ISR. ISR as compared to no-ISR was associated with a consistent increased risk of MACE within the normal weight (18.8% vs. 7.8%, adj. hazard ratio (HR): 1.99, 95% confidence interval [CI]: 1.51-2.64), overweight (19.1% vs. 6.4%, adj. HR: 2.35, 95% CI: 1.91-2.88), class I obesity (18.3% vs. 6.8%, adj. HR: 1.95, 95% CI: 1.47-2.57), and class II-III obesity (16.4% vs. 7.4%, adj. HR: 1.61, 95% CI: 1.09-2.37) groups (interaction p-value: 0.192). The ISR-related risks were mostly driven by an excess of TVR. CONCLUSIONS: At 1 year, ISR was associated with an increased risk of MACE irrespective of BMI, mostly due to an excess of TVR after ISR.

Making meaning from materialsHandmade: A Scientist's Search for Meaning Through Making Anna Ploszajski Bloomsbury, 2023. 320 pp.

Hands-on experiences can deepen our understanding of the substances that surround us.

Prognostic value of high-sensitivity C-reactive protein among chronic kidney disease patients undergoing percutaneous coronary intervention.

BACKGROUND: Data on the prognostic value of high-sensitivity C-reactive protein (hs-CRP) levels in patients with chronic kidney disease (CKD) undergoing percutaneous coronary intervention (PCI) are limited. METHODS: Patients undergoing PCI at a tertiary center from January 2012 to December 2019 were included. CKD was defined as a glomerular filtration rate (GFR) <60 mL/min/1.73m2 and elevated hs-CRP was defined as >3 mg/L. Acute myocardial infarction (MI), acute heart failure, neoplastic disease, patients undergoing hemodialysis, or hs-CRP >10 mg/L were exclusion criteria. The primary outcome was major adverse cardiac events (MACE), a composite of all-cause death, MI, and target vessel revascularization at 1-year after PCI. RESULTS: Out of 12,410 patients, 3029 (24.4 %) had CKD. Elevated hs-CRP levels were found in 31.8 % of CKD and 25.8 % of no-CKD patients. At 1 year, MACE occurred in 87 (11.0 %) CKD patients with elevated hs-CRP and 163 (9.5 %) with low hs-CRP (adj. HR 1.26, 95 % CI 0.94-1.68); among no-CKD patients, in 200 (10 %) and 470 (8.1 %), respectively (adj. HR 1.21, 95 % CI 1.00-1.45). Hs-CRP was associated with an increased risk of all-cause death in both CKD (Adj. HR 1.92, 95 % CI 1.07-3.44) and no-CKD patients (adj. HR 3.02, 95 % CI 1.74-5.22). There was no interaction between hs-CRP and CKD status. CONCLUSIONS: Among patients undergoing PCI without acute MI, elevated hs-CRP values were not associated with a higher risk of MACE at 1 year, but with increased mortality hazards consistently in patients with or without CKD.

Prognostic Value of Baseline Inflammation in Diabetic and Nondiabetic Patients Undergoing Percutaneous Coronary Intervention.

BACKGROUND: There is a paucity of data on the prognostic value of high-sensitivity C-reactive protein (hsCRP) levels in diabetic and nondiabetic patients undergoing percutaneous coronary intervention (PCI). METHODS: All patients with known baseline hsCRP undergoing PCI at a single tertiary care centre from 2010 to 2017 were included. High hsCRP was defined as > 3 mg/L. Known causes of elevated hsCRP levels and hsCRP > 10 mg/L represented exclusion criteria. The 1-year primary outcome was major adverse cardiovascular events (MACE), including all-cause mortality, myocardial infarction (MI), and target-vessel revascularisation (TVR). RESULTS: Among a total of 11,979 patients included, high hsCRP levels were observed in 24.7% of patients without diabetes and 29.8% of patients with diabetes (P < 0.001). Both diabetics and nondiabetics with high hsCRP levels had increased rates of MACE compared with their counterparts with low hsCRP (diabetics: adjusted hazard ratio [aHR] 1.58, 95% CI 1.27-1.96; nondiabetics: aHR 1.45, 95% CI 1.13-1.86; P interaction = 0.981) primarily driven by increased rates all-cause deaths (diabetics: aHR 2.32, 95% CI 1.42-3.80; nondiabetics: aHR 3.14, 95% CI 1.74-5.65; P interaction = 0.415). Although high hsCRP levels were associated with increased rates of TVR (aHR 1.35, 95% CI 1.04-1.75) and MI (aHR 1.86, 95% CI 1.18-2.93) only in patients with diabetes, no significant interactions were observed between inflammation and diabetes (P interaction = 0.749 and 0.602, respectively). CONCLUSIONS: Patients undergoing PCI with high levels of hsCRP, defined as > 3 mg/L, have worse ischemic outcomes regardless of diabetes status.

SGLT-2 inhibitors and cardiovascular outcomes in patients with and without a history of heart failure: a systematic review and meta-analysis.

AIMS: Sodium-glucose cotransporter 2 (SGLT-2) inhibitors have cardiovascular (CV) benefits in patients with heart failure with reduced ejection fraction (HFrEF). Whether these medications improve CV outcomes irrespective of heart failure history or left ventricular ejection fraction (LVEF) in HFrEF remains unknown. METHODS AND RESULTS: All randomized, placebo-controlled trials of SGLT-2 inhibitors reporting similar CV outcomes were searched in PubMed from 1 January 2010 to 1 October 2021. The primary outcome was the composite of hospitalization for heart failure or CV death. Secondary outcomes included all-cause mortality. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were used as effect estimates and calculated with a random-effects model. Data from 11 trials and a total of 66 957 patients (n = 36 758 SGLT-2 group, n = 30 199 placebo group) were included. SGLT-2 inhibitors reduced the risk of hospitalization for heart failure or CV death in patients with (HR 0.76, 95% CI 0.71-0.80) and without (HR 0.76, 95% CI 0.68-0.86; Pinteraction = 0.69) heart failure. Patients with (HR 0.87, 95% CI 0.80-0.95) and without (HR 0.84, 95% CI 0.73-0.95; Pinteraction = 0.67) heart failure treated with SGLT-2 inhibitors had a reduction in all-cause mortality. Reduction in the primary outcome was consistently observed in HFrEF patients with (HR 0.68, 95% CI 0.59-0.78) and without (HR 0.84, 95% CI 0.71-0.99; Pinteraction = 0.13) severely reduced LVEF, and in heart failure with preserved ejection fraction patients (HR 0.80, 95% CI 0.70-0.92; Pinteraction = 0.65). CONCLUSION: SGLT-2 inhibitors improved CV outcomes irrespective of heart failure history or type, and severity of LVEF reduction.

Performance of the academic research consortium high-bleeding risk criteria in patients undergoing PCI for acute myocardial infarction.

Patients undergoing percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) are at increased risk for thrombotic and bleeding complications compared to patients with chronic coronary syndrome (CCS). The academic research consortium (ARC) recently suggested a set of criteria to identify patients at high bleeding risk (HBR). We sought to evaluate the performance of the ARC-HBR criteria among patients undergoing PCI according to clinical presentation. We included all consecutive patients undergoing PCI at a tertiary-care center. Patients were deemed at HBR if they fulfilled ≥ 1 major or ≥ 2 minor ARC-HBR criteria. The primary bleeding endpoint was a composite of in-hospital or post-discharge bleeding at 1-year follow-up. Secondary outcomes included all-cause death and myocardial infarction. Out of 6068 patients, 1391 (22.9 %) presented with AMI and were more often at HBR than those with CCS (46.9 % vs. 43.0 %, p = 0.01). HBR patients had a higher risk for the primary bleeding endpoint than non-HBR, irrespective of the clinical indication for PCI (AMI: 19.5 % vs. 5.5 %; HR 3.86, 95 % CI 2.63-5.69; CCS: 6.8 % vs. 2.6 %; HR 2.65, 95 % CI 1.92-3.68; p-interaction = 0.11). Secondary outcomes followed a similar trend. After multivariable adjustment, AMI presentation remained significantly associated with increased risk for bleeding at 1 year (HR 1.64, 95 % CI 1.13-2.38, p = 0.01). The ARC-HBR criterion associated with the highest bleeding risk was severe/end-stage chronic kidney disease in AMI and moderate/severe anemia in CCS. The ARC-HBR framework successfully identified AMI and CCS patients with increased risk for bleeding complications at 1 year post-PCI. Figure prepared with BioRender.

Impact of target vessel choice on outcomes following percutaneous coronary intervention in patients with a prior coronary artery bypass graft.

OBJECTIVES: To evaluate and compare characteristics and clinical outcomes of percutaneous coronary intervention (PCI) among target vessel types in patients with a prior coronary artery bypass graft (CABG) surgery. BACKGROUND: Patients with a prior CABG often require repeat revascularization with PCI. Graft PCI has been associated with worse outcomes compared to native vessel PCI, yet the optimal PCI strategy in prior CABG patients remains unknown. METHODS: We stratified prior CABG patients who underwent PCI at a tertiary-care center between 2009 and 2017 by target vessel type: native vessel, venous graft, and arterial graft. The primary outcome of major adverse cardiac events (MACE) was a composite of all-cause death, myocardial infarction, stent thrombosis, or target vessel revascularization up to 1 year post-PCI. RESULTS: Prior CABG patients (n = 3983) represented 19.5% of all PCI interventions during the study period. PCI was most frequently performed on native vessels (n = 2928, 73.5%) followed by venous (n = 883, 22.2%) and arterial grafts (n = 172, 4.3%). Procedural success and complications were similar among the groups; however, slow- and no-reflow phenomenon was more common in venous graft PCI compared to native vessel PCI (OR 4.78; 95% CI 2.56-8.95; p < 0.001). At 1 year, there were no significant differences in MACE or in its individual components. CONCLUSIONS: Target vessel choice did not appear to affect MACE at 1 year in a large cohort of patients with prior CABG undergoing PCI. Whether PCI of surgical grafts versus native arteries truly results in similar outcomes warrants further investigation in randomized controlled trials.

DRAXIN regulates interhemispheric fissure remodelling to influence the extent of corpus callosum formation.

Corpus callosum dysgenesis (CCD) is a congenital disorder that incorporates either partial or complete absence of the largest cerebral commissure. Remodelling of the interhemispheric fissure (IHF) provides a substrate for callosal axons to cross between hemispheres, and its failure is the main cause of complete CCD. However, it is unclear whether defects in this process could give rise to the heterogeneity of expressivity and phenotypes seen in human cases of CCD. We identify incomplete IHF remodelling as the key structural correlate for the range of callosal abnormalities in inbred and outcrossed BTBR mouse strains, as well as in humans with partial CCD. We identify an eight base-pair deletion in Draxin and misregulated astroglial and leptomeningeal proliferation as genetic and cellular factors for variable IHF remodelling and CCD in BTBR strains. These findings support a model where genetic events determine corpus callosum structure by influencing leptomeningeal-astroglial interactions at the IHF.

Clinical characteristics of acute lower extremity deep venous thrombosis diagnosed by duplex in patients hospitalized for coronavirus disease 2019.

OBJECTIVE: Little is known about coronavirus disease 2019 (COVID-19)-associated hypercoagulability. We sought to characterize patients with deep venous thrombosis (DVT) identified after admission for COVID-19. METHODS: All adult patients admitted to Montefiore Medical Center from March 1, 2020, to April 10, 2020, and undergoing lower extremity venous duplex for DVT evaluation were included. Patients admitted with suspicion of COVID-19 were divided into severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive and SARS-CoV-2 negative groups based on in-hospital test results. Patients without clinical suspicion for COVID-19 were not tested. A retrospective case-control study design was used to identify potential risk factors for DVT in patients with COVID-19. Demographic, radiographic, and laboratory values were abstracted and analyzed. RESULTS: During the study period, 3404 patients with confirmed COVID-19 were admitted to the hospital. Of the 135 SARS-CoV-2 patients who underwent duplex scanning, there were 18 (13.3%) noted to have DVT compared with 72 of the 711 patients (10.1%) who were either SARS-CoV-2 negative or untested. The odds ratio for DVT in COVID-19 was 1.35 (95% confidence interval, 0.78-2.34; P = .289). Baseline characteristics for COVID-19 patients with and without DVT were overall similar. COVID-19 patients with DVT had an elevated median first d-dimer (18.88 µg/mL [interquartile range (IQR), 7.79-20.00] vs 2.55 µg/mL [IQR, 1.45-6.28]; P = .002; reference value, <0.5 µg/mL), average in-hospital d-dimer (median, 11.93 µg/mL [IQR, 8.25-16.97] vs 3.54 µg/mL [IQR, 2.05-8.53]; P < .001) and median fibrinogen level (501.0 [IQR, 440.0-629.0] vs 654.5 [IQR, 535.8-780.0]; P = .002; reference range, 187-502 mg/dL). There was a trend to significance for COVID-19 patients with DVT compared with without DVT in median d-dimer levels at the time of the duplex (13.61 µg/mL [IQR, 4.04-19.97] vs 3.58 µg/mL [IQR, 2.51-9.62]; P = .055) and median ferritin levels (1679.0 ng/mL [IQR, 1168.0-2577.0] vs 1103.0 ng/mL [IQR, 703.5-2076.5]; P = .055; reference range, 25-270 ng/mL). Twelve of the 18 patients with COVID who developed DVT did so despite chemical thromboprophylaxis, and 2 developed DVT despite therapeutic anticoagulation CONCLUSIONS: We found only a modestly increased risk of DVT in patients with COVID-19, likely underestimated owing to limitations in duplex testing early in the epidemic. Elevated d-dimer and a less elevated fibrinogen are associated with DVT in patients with COVID-19 who seem to form thrombus despite conventional chemical thromboprophylaxis. Additionally, an increasing d-dimer over time may be a reflection of the development of DVT in patients with COVID-19.

Early experience with arterial thromboembolic complications in patients with COVID-19.

BACKGROUND: Little is known about the arterial complications and hypercoagulability associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We sought to characterize our experience with arterial thromboembolic complications in patients with hospitalized for coronavirus disease 2019 (COVID-19). METHODS: All patients admitted from March 1 to April 20, 2020, and who underwent carotid, upper, lower and aortoiliac arterial duplex, computed tomography angiogram or magnetic resonance angiography for suspected arterial thrombosis were included. A retrospective case control study design was used to identify, characterize and evaluate potential risk factors for arterial thromboembolic disease in SARS-CoV-2 positive patients. Demographics, characteristics, and laboratory values were abstracted and analyzed. RESULTS: During the study period, 424 patients underwent 499 arterial duplex, computed tomography angiogram, or magnetic resonance angiography imaging studies with an overall 9.4% positive rate for arterial thromboembolism. Of the 40 patients with arterial thromboembolism, 25 (62.5%) were SARS-CoV-2 negative or admitted for unrelated reasons and 15 (37.5%) were SARS-CoV-2 positive. The odds ratio for arterial thrombosis in COVID-19 was 3.37 (95% confidence interval, 1.68-6.78; P = .001). Although not statistically significant, in patients with arterial thromboembolism, patients who were SARS-CoV-2 positive compared with those testing negative or not tested tended to be male (66.7% vs 40.0%; P = .191), have a less frequent history of former or active smoking (42.9% vs 68.0%; P = .233) and have a higher white blood cell count (14.5 vs 9.9; P = .208). Although the SARS-CoV-2 positive patients trended toward a higher the neutrophil-to-lymphocyte ratio (8.9 vs 4.1; P = .134), creatinine phosphokinase level (359.0 vs 144.5; P = .667), C-reactive protein level (24.2 vs 13.8; P = .627), lactate dehydrogenase level (576.5 vs 338.0; P = .313), and ferritin level (974.0 vs 412.0; P = .47), these differences did not reach statistical significance. Patients with arterial thromboembolic complications and SARS-CoV-2 positive when compared with SARS-CoV-2 negative or admitted for unrelated reasons were younger (64 vs 70 years; P = .027), had a significantly higher body mass index (32.6 vs 25.5; P = .012), a higher d-dimer at the time of imaging (17.3 vs 1.8; P = .038), a higher average in hospital d-dimer (8.5 vs 2.0; P = .038), a greater distribution of patients with clot in the aortoiliac location (5 vs 1; P = .040), less prior use of any antiplatelet medication (21.4% vs 62.5%; P = .035), and a higher mortality rate (40.0% vs 8.0%; P = .041). Treatment of arterial thromboembolic disease in COVID-19 positive patients included open thromboembolectomy in six patients (40%), anticoagulation alone in four (26.7%), and five (33.3%) did not require or their overall illness severity precluded additional treatment. CONCLUSIONS: Patients with SARS-CoV-2 are at risk for acute arterial thromboembolic complications despite a lack of conventional risk factors. A hyperinflammatory state may be responsible for this phenomenon with a preponderance for aortoiliac involvement. These findings provide an early characterization of arterial thromboembolic disease in SARS-CoV-2 patients.

A Head-to Head Comparison of Machine Learning Algorithms for Identification of Implanted Cardiac Devices.

Application of artificial intelligence techniques in medicine has rapidly expanded in recent years. Two algorithms for identification of cardiac implantable electronic devices using chest radiography were recently developed: The PacemakerID algorithm, available as a mobile phone application (PIDa) and a web platform (PIDw) and The Pacemaker Identification with Neural Networks (PPMnn), available via web platform. In this study, we assessed the relative accuracy of these algorithms. The machine learning algorithms (PIDa, PIDw, PPMnn) were used to predict device manufacturer using chest X-rays for patients with implanted devices. Each prediction was considered correct if predicted certainty was >75%. For comparative purposes, accuracy of each prediction was compared to the result using the CARDIA-X algorithm. 500 X-rays were included from a convenience sample. Raw accuracy was PIDa 89%, PIDw 73%, PPMnn 71% and CARDIA-X 85%. In conclusion, machine learning algorithms for identification of cardiac devices are accurate at determining device manufacturer, have capacity for improved accuracy with additional training sets and can utilize simple user interfaces. These algorithms have clinical utility in limiting potential infectious exposures and facilitate rapid identification of devices as needed for device reprogramming.

Perspective: The Alzheimer's Disease Neuroimaging Initiative and the role and contributions of the Private Partner Scientific Board (PPSB).

The Alzheimer's Disease Neuroimaging Initiative (ADNI) Private Partner Scientific Board (PPSB) is comprised of representatives of private, for-profit entities (including pharmaceutical, biotechnology, diagnostics, imaging companies, and imaging contract research organizations), and nonprofit organizations that provide financial and scientific support to ADNI through the Foundation for the National Institutes of Health. The PPSB serves as an independent, open, and precompetitive forum in which all private sector and not-for-profit partners in ADNI can collaborate, share information, and offer scientific and private-sector perspectives and expertise on issues relating to the ADNI project. In this article, we review and highlight the role, activities, and contributions of the PPSB within the ADNI project, and provide a perspective on remaining unmet needs and future directions.

The impact of the Alzheimer's Disease Neuroimaging Initiative 2: What role do public-private partnerships have in pushing the boundaries of clinical and basic science research on Alzheimer's disease?

In the growing landscape of biomedical public-private-partnerships, particularly for Alzheimer's disease, the question is posed as to their value. What impacts do public-private-partnerships have on clinical and basic science research in Alzheimer's disease? The authors answer the question using the Alzheimer's Disease Neuroimaging Initiative (ADNI) as a test case and example. ADNI is an exemplar of how public-private-partnerships can make an impact not only on clinical and basic science research and practice (including clinical trials), but also of how similar partnerships using ADNI as an example, can be designed to create a maximal impact within their fields.

Mapk/Erk activation in an animal model of social deficits shows a possible link to autism.

BACKGROUND: There is converging preclinical and clinical evidence to suggest that the extracellular signal-regulated kinase (ERK) signaling pathway may be dysregulated in autism spectrum disorders. METHOD: We evaluated Mapk/Erk1/2, cellular proliferation and apoptosis in BTBR mice, as a preclinical model of Autism. We had previously generated 410 F2 mice from the cross of BTBR with B6. At that time, six different social behaviors in all F2 mice were evaluated and scored. In this study, eight mice at each extreme of the social behavioral spectrum were selected and the expression and activity levels of Mapk/Erk in the prefrontal cortex and cerebellum of these mice were compared. Finally, we compared the Mapk/Erk signaling pathway in brain and lymphocytes of the same mice, testing for correlation in the degree of kinase activation across these separate tissues. RESULTS: Levels of phosphorylated Erk (p-Erk) were significantly increased in the brains of BTBR versus control mice. We also observed a significant association between juvenile social behavior and phosphorylated mitogen-activated protein kinase kinase (p-Mek) and p-Erk levels in the prefrontal cortex but not in the cerebellum. In contrast, we did not find a significant association between social behavior and total protein levels of either Mek or Erk. We also tested whether steady-state levels of Erk activation in the cerebral cortex in individual animals correlated with levels of Erk activation in lymphocytes, finding a significant relationship for this signaling pathway. CONCLUSION: These observations suggest that dysregulation of the ERK signaling pathway may be an important mediator of social behavior, and that measuring activation of this pathway in peripheral lymphocytes may serve as a surrogate marker for central nervous system (CNS) ERK activity, and possibly autistic behavior.

Quantitative trait loci for interhemispheric commissure development and social behaviors in the BTBR T⁺ tf/J mouse model of autism.

BACKGROUND: Autism and Agenesis of the Corpus Callosum (AgCC) are interrelated behavioral and anatomic phenotypes whose genetic etiologies are incompletely understood. We used the BTBR T⁺ tf/J (BTBR) strain, exhibiting fully penetrant AgCC, a diminished hippocampal commissure, and abnormal behaviors that may have face validity to autism, to study the genetic basis of these disorders. METHODS: We generated 410 progeny from an F2 intercross between the BTBR and C57BL/6J strains. The progeny were phenotyped for social behaviors (as juveniles and adults) and commisural morphology, and genotyped using 458 markers. Quantitative trait loci (QTL) were identified using genome scans; significant loci were fine-mapped, and the BTBR genome was sequenced and analyzed to identify candidate genes. RESULTS: Six QTL meeting genome-wide significance for three autism-relevant behaviors in BTBR were identified on chromosomes 1, 3, 9, 10, 12, and X. Four novel QTL for commissural morphology on chromosomes 4, 6, and 12 were also identified. We identified a highly significant QTL (LOD score = 20.2) for callosal morphology on the distal end of chromosome 4. CONCLUSIONS: We identified several QTL and candidate genes for both autism-relevant traits and commissural morphology in the BTBR mouse. Twenty-nine candidate genes were associated with synaptic activity, axon guidance, and neural development. This is consistent with a role for these processes in modulating white matter tract development and aspects of autism-relevant behaviors in the BTBR mouse. Our findings reveal candidate genes in a mouse model that will inform future human and preclinical studies of autism and AgCC.

Loss of microRNAs in pyramidal neurons leads to specific changes in inhibitory synaptic transmission in the prefrontal cortex.

MicroRNAs (miRNAs) are critical regulators of nervous system function, and in vivo knockout studies have demonstrated that miRNAs are necessary for multiple aspects of neuronal development and survival. However, the role of miRNA biogenesis in the formation and function of synapses in the cerebral cortex is only minimally understood. Here, we have generated and characterized a mouse line with a conditional neuronal deletion of Dgcr8, a miRNA biogenesis protein predicted to process miRNAs exclusively. Loss of Dgcr8 in pyramidal neurons of the cortex results in a non-cell-autonomous reduction in parvalbumin interneurons in the prefrontal cortex, accompanied by a severe deficit in inhibitory synaptic transmission and a corresponding reduction of inhibitory synapses. Together, these results suggest a vital role for miRNAs in governing essential aspects of inhibitory transmission and interneuron development in the mammalian nervous system. These results may be relevant to human diseases such as schizophrenia, where both altered Dgcr8 levels as well as aberrant inhibitory transmission in the prefrontal cortex have been postulated to contribute to the pathophysiology of the disease.

Glutamine uptake by System A transporters maintains neurotransmitter GABA synthesis and inhibitory synaptic transmission.

GABA synthesis is necessary to maintain synaptic vesicle filling, and key proteins in its biosynthetic pathways may play a role in regulating inhibitory synaptic stability and strength. GABAergic neurons require a source of precursor glutamate, possibly from glutamine, although it is controversial whether glutamine contributes to the synaptic pool of GABA. Here we report that inhibition of System A glutamine transporters with alpha-(methyl-amino) isobutyric acid rapidly reduced the amplitude of inhibitory post-synaptic currents and miniature inhibitory post-synaptic currents (mIPSCs) recorded in rat hippocampal area cornu ammonis 1 (CA1) pyramidal neurons, indicating that synaptic vesicle content of GABA was reduced. After inhibiting astrocytic glutamine synthesis by either blocking glutamate transporters or the glutamine synthetic enzyme, the effect of alpha-(methyl-amino) isobutyric acid on mIPSC amplitudes was abolished. Exogenous glutamine did not affect mIPSC amplitudes, suggesting that the neuronal transporters are normally saturated. Our findings demonstrate that a constitutive supply of glutamine is provided by astrocytes to inhibitory neurons to maintain vesicle filling. Therefore, glutamine transporters, like those for glutamate, are potential regulators of inhibitory synaptic strength. However, in contrast to glutamate, extracellular glutamine levels are normally high. Therefore, we propose a supportive role for glutamine, even under resting conditions, to maintain GABA vesicle filling.

Cortical inhibition modified by embryonic neural precursors grafted into the postnatal brain.

Embryonic medial ganglionic eminence (MGE) cells transplanted into the adult brain can disperse, migrate, and differentiate to neurons expressing GABA, the primary inhibitory neurotransmitter. It has been hypothesized that grafted MGE precursors could have important therapeutic applications increasing local inhibition, but there is no evidence that MGE cells can modify neural circuits when grafted into the postnatal brain. Here we demonstrate that MGE cells grafted into one location of the neonatal rodent brain migrate widely into cortex. Grafted MGE-derived cells differentiate into mature cortical interneurons; the majority of these new interneurons express GABA. Based on their morphology and expression of somatostatin, neuropeptide Y, parvalbumin, or calretinin, we infer that graft-derived cells integrate into local circuits and function as GABA-producing inhibitory cells. Whole-cell current-clamp recordings obtained from MGE-derived cells indicate firing properties typical of mature interneurons. Moreover, patch-clamp recordings of IPSCs on pyramidal neurons in the host brain, 30 and 60 d after transplantation, indicated a significant increase in GABA-mediated synaptic inhibition in regions containing transplanted MGE cells. In contrast, synaptic excitation is not altered in the host brain. Grafted MGE cells, therefore, can be used to modify neural circuits and selectively increase local inhibition. These findings could have important implications for reparative cell therapies for brain disorders.

Structural determinants of benzodiazepine allosteric regulation of GABA(A) receptor currents.

Benzodiazepine enhancement of GABA(A) receptor current requires a gamma subunit, and replacement of the gamma subunit by the delta subunit abolishes benzodiazepine enhancement. Although it has been demonstrated that benzodiazepines bind to GABA(A) receptors at the junction between alpha and gamma subunits, the structural basis for the coupling of benzodiazepine binding to allosteric enhancement of the GABA(A) receptor current is unclear. To determine the structural basis for this coupling, the present study used a chimera strategy, using gamma2L-delta GABA(A) receptor subunit chimeras coexpressed with alpha1 and beta3 subunits in human embryonic kidney 293T cells. Different domains of the gamma2L subunit were replaced by delta subunit sequence, and diazepam sensitivity was determined. Chimeric subunits revealed two areas of interest: domain 1 in transmembrane domain 1 (M1) and domain 2 in the C-terminal portion of transmembrane domain 2 (M2) and the M2-M3 extracellular loop. In those domains, site-directed mutagenesis demonstrated that the following two groups of residues were involved in benzodiazepine transduction of current enhancement: residues Y235, F236, T237 in M1; and S280, T281, I282 in M2 as well as the entire M2-M3 loop. These results suggest that a pocket of residues may transduce benzodiazepine binding to increased gating. Benzodiazepine transduction involves a group of residues that connects the N terminus and M1, and another group of residues that may facilitate an interaction between the N terminus and the M2 and M2-M3 loop domains.