Publications by authors named "Scott Callahan"

Article Synopsis
  • * This pilot study aimed to integrate a remote exam device into a complex care clinic during the COVID-19 pandemic, focusing on training caregivers and evaluating the device's usability and feasibility.
  • * While caregivers rated the device as highly usable, providers found it less so, and technology issues led to 15% of telemedicine encounters being canceled or cut short; overall, the device was successfully incorporated into the clinic.
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Background: Children and young adults with medical complexity (CMC) experience high rates of healthcare reutilization following hospital discharge. Prior studies have identified common hospital-to-home transition failures that may increase the risk for reutilization, including medication, technology and equipment issues, financial concerns, and confusion about which providers can help with posthospitalization needs. Few interventions have been developed and evaluated for CMC during this transition period.

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Objectives: To assess the association between neighborhood socioeconomic deprivation and health care utilization in a cohort of children with medical complexity (CMC).

Methods: Cross-sectional study of children aged <18 years receiving care in our institution's patient-centered medical home (PCMH) for CMC in 2016 to 2017. Home addresses were assigned to census tracts and a tract-level measure of socioeconomic deprivation (Deprivation Index with range 0-1, higher numbers represent greater deprivation).

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Oncogenes only transform cells under certain cellular contexts, a phenomenon called oncogenic competence. Using a combination of a human pluripotent stem cell–derived cancer model along with zebrafish transgenesis, we demonstrate that the transforming ability of BRAF along with additional mutations depends on the intrinsic transcriptional program present in the cell of origin. In both systems, melanocytes are less responsive to mutations, whereas both neural crest and melanoblast populations are readily transformed.

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Autism is a clinically heterogeneous neurodevelopmental disorder characterized by impaired social interactions, restricted interests, and repetitive behaviors. Despite significant advances in the genetics of autism, understanding how genetic changes perturb brain development and affect clinical symptoms remains elusive. Here, we present a multiplex human pluripotent stem cell (hPSC) platform, in which 30 isogenic disease lines are pooled in a single dish and differentiated into prefrontal cortex (PFC) lineages to efficiently test early-developmental hypotheses of autism.

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Transgenic animals are invaluable for modeling cancer genomics, but often require complex crosses of multiple germline alleles to obtain the desired combinations. Zebrafish models have advantages in that transgenes can be rapidly tested by mosaic expression, but typically lack spatial and temporal control of tumor onset, which limits their utility for the study of tumor progression and metastasis. To overcome these limitations, we have developed a method referred to as Transgene Electroporation in Adult Zebrafish (TEAZ).

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Patterning of vertebrate melanophores is essential for mate selection and protection from UV-induced damage. Patterning can be influenced by circulating long-range factors, such as hormones, but it is unclear how their activity is controlled in recipient cells to prevent excesses in cell number and migration. The zebrafish wanderlust mutant harbors a mutation in the sheddase bace2 and exhibits hyperdendritic and hyperproliferative melanophores that localize to aberrant sites.

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The creation of restriction enzymes with programmable DNA-binding and -cleavage specificities has long been a goal of modern biology. The recently discovered Type IIL MmeI family of restriction-and-modification (RM) enzymes that possess a shared target recognition domain provides a framework for engineering such new specificities. However, a lack of structural information on Type IIL enzymes has limited the repertoire that can be rationally engineered.

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Human pluripotent stem cells (hPSCs) represent a platform to study human development in vitro under both normal and disease conditions. Researchers can direct the differentiation of hPSCs into the cell type of interest by manipulating the culture conditions to recapitulate signals seen during development. One such cell type is the melanocyte, a pigment-producing cell of neural crest (NC) origin responsible for protecting the skin against UV irradiation.

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Type IIL restriction enzymes have rejuvenated the search for user-specified DNA binding and cutting. By aligning and contrasting the highly comparable amino-acid sequences yet diverse recognition specificities across the family of enzymes, amino acids involved in DNA binding have been identified and mutated to produce alternative binding specificities. To date, the specificity of MmeI (a type IIL restriction enzyme) has successfully been altered at positions 3, 4 and 6 of the asymmetric TCCRAC (where R is a purine) DNA-recognition sequence.

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