Surgical Considerations in Shone Complex.

Shone complex is defined by 4 anomalies: parachute mitral valve, supravalvar mitral ring, subaortic stenosis, and coarctation of the aorta. Establishing a clear definition is one of the principal challenges in the study of Shone complex as not all patients have all lesions. The essential feature of Shone complex is multilevel left-sided obstruction involving both the left ventricular inflow and outflow. This anatomic variability is reflected in the clinical presentation as signs of left ventricular inflow obstruction are often masked by outflow obstruction and the multilevel nature of the condition is thus underappreciated. Surgical treatment is often stepwise addressing the outflow obstruction first. In this review, geared to the pediatric cardiac anesthesiologist, we review the pathophysiology, diagnosis, treatment, and outcomes of Shone complex.

Development of a 3-D printing-based cardiac surgical simulation curriculum to teach septal myectomy.

OBJECTIVE: We sought to develop a 3-D printing-based simulator for teaching extended septal myectomy to trainees in cardiothoracic surgery (clinical postgraduate year 4-7). This procedure is difficult to teach because of generally unfamiliar and highly variable anatomy, limited visibility for the assistant, and significant potential complications. METHODS: A curriculum using multimedia didactics and 3-D print-based patient-specific surgical simulation was implemented. Six identical 3-D prints were constructed for each of 5 consecutive patients. Preoperative septal myectomy was performed on each printed heart by an attending surgeon and 5 residents. Model myectomy specimen volumes were measured according to liquid displacement. All print resections were videotaped and blindly evaluated by 3 attending surgeons. Pre- and post-test evaluations, and a survey tool were also used to evaluate the curriculum. RESULTS: Baseline myectomy resection volumes differed significantly (attending 15 cm3 vs resident 3.1 cm3; P < .05). Residents resected increasingly larger volumes of tissue over the course of the study. Initial resection volume (compared with faculty) increased by 0.82 cm3 per resection (95% confidence interval, 0.37-1.3 cm3; P < .0001). Total resection volume (compared with faculty) increased by 3.6 cm3 per resection (95% confidence interval, 2.4-4.9 cm3; P < .0001). The residents' survey assessment of the simulator was favorable. CONCLUSIONS: A patient-specific 3-D printing-based simulation module shows promise as a tool to augment and improve cardiothoracic resident training in septal myectomy. The residents were quickly able to perform resections on par with the attending. Residents rated the simulator favorably. Each resident benefited by experiencing the variable anatomy of 5 separate patient-specific models.

Tbr2 is essential for hippocampal lineage progression from neural stem cells to intermediate progenitors and neurons.

Neurogenesis in the dentate gyrus has been implicated in cognitive functions, including learning and memory, and may be abnormal in major neuropsychiatric disorders, such as depression. Dentate neurogenesis is regulated by interactions between extrinsic factors and intrinsic transcriptional cascades that are currently not well understood. Here we show that Tbr2 (also known as Eomes), a T-box transcription factor expressed by intermediate neuronal progenitors (INPs), is critically required for neurogenesis in the dentate gyrus of developing and adult mice. In the absence of Tbr2, INPs are depleted despite augmented neural stem cell (NSC) proliferation, and neurogenesis is halted as the result of failed neuronal differentiation. Interestingly, we find that Tbr2 likely promotes lineage progression from NSC to neuronal-specified INP in part by repression of Sox2, a key determinant of NSC identity. These findings suggest that Tbr2 expression in INPs is critical for neuronal differentiation in the dentate gyrus and that INPs are an essential stage in the lineage from NSCs to new granule neurons in the dentate gyrus.

Adult generation of glutamatergic olfactory bulb interneurons.

The adult mouse subependymal zone (SEZ) harbors neural stem cells that are thought to exclusively generate GABAergic interneurons of the olfactory bulb. We examined the adult generation of glutamatergic juxtaglomerular neurons, which had dendritic arborizations that projected into adjacent glomeruli, identifying them as short-axon cells. Fate mapping revealed that these originate from Neurog2- and Tbr2-expressing progenitors located in the dorsal region of the SEZ. Examination of the progenitors of these glutamatergic interneurons allowed us to determine the sequential expression of transcription factors in these cells that are thought to be hallmarks of glutamatergic neurogenesis in the developing cerebral cortex and adult hippocampus. Indeed, the molecular specification of these SEZ progenitors allowed for their recruitment into the cerebral cortex after a lesion was induced. Taken together, our data indicate that SEZ progenitors not only produce a population of adult-born glutamatergic juxtaglomerular neurons, but may also provide a previously unknown source of progenitors for endogenous repair.