Ultrasound-guided fine-needle aspiration biopsy of pediatric thyroid nodules.

BACKGROUND: The role of US-guided fine-needle aspiration biopsy (US-FNAB) of thyroid nodules is not well-established in children. OBJECTIVE: To retrospectively assess the utility of US-FNAB of pediatric thyroid nodules. MATERIALS AND METHODS: We reviewed Department of Radiology records to identify children who underwent US-FNAB of the thyroid between 2005 and 2013. Two board-certified pediatric radiologists reviewed pre-procedural thyroid US exams and documented findings by consensus. We recorded cytopathology findings and compared them to surgical pathology diagnoses if the nodule was resected. We also recorded demographic information, use of sedation or general anesthesia, and presence of on-site cytopathological feedback. The Student's t-test was used to compare continuous data; the Fisher exact test was used to compare proportions. RESULTS: US-FNAB was conducted on a total of 86 thyroid nodules in 70 children; 56 were girls (80%). Seventy-eight of the 86 (90.7%) US-FNAB procedures were diagnostic; 69/78 (88.5%) diagnostic specimens were benign (including six indeterminate follicular lesions that were proved at surgery to be benign) and 9/78 (11.5%) were malignant/suspicious for malignancy (all proved to be papillary carcinomas). There was no difference in size of benign vs. malignant lesions (P = 0.82) or diagnostic vs. non-diagnostic lesions (P = 0.87). Gender (P = 0.19), use of sedation/general anesthesia (P = 0.99), and presence of onsite cytopathological feedback (P = 0.99) did not affect diagnostic adequacy. Microcalcifications (P < 0.0001; odds ratio [OR] = 113.7) and coarse calcifications (P = 0.03; OR = 19.4) were associated with malignancy. Diagnoses at cytopathology and surgical pathology were concordant in 27/29 (93.1%) nodules; no US-FNAB procedure yielded false-positive or false-negative results for malignancy. CONCLUSION: US-FNAB of pediatric thyroid nodules is feasible, allows diagnostic cytopathological evaluation, and correlates with surgical pathology results in resected nodules.

NanoLuc reporter for dual luciferase imaging in living animals.

Bioluminescence imaging is widely used for cell-based assays and animal imaging studies in biomedical research and drug development, capitalizing on the high signal to background of this technique. A relatively small number of luciferases are available for imaging studies, substantially limiting the ability to image multiple molecular and cellular events, as done commonly with fluorescence imaging. To advance dual reporter bioluminescence molecular imaging, we tested a recently developed, adenosine triphosphate­independent luciferase enzyme from Oplophorus gracilirostris (NanoLuc [NL]) as a reporter for animal imaging. We demonstrated that NL could be imaged in superficial and deep tissues in living mice, although the detection of NL in deep tissues was limited by emission of predominantly blue light by this enzyme. Changes in bioluminescence from NL over time could be used to quantify tumor growth, and secreted NL was detectable in small volumes of serum. We combined NL and firefly luciferase reporters to quantify two key steps in transforming growth factor ß signaling in intact cells and living mice, establishing a novel dual luciferase imaging strategy for quantifying signal transduction and drug targeting. Our results establish NL as a new reporter for bioluminescence imaging studies in intact cells and living mice that will expand imaging of signal transduction in normal physiology, disease, and drug development.

Carboxy-terminus of CXCR7 regulates receptor localization and function.

Chemokine receptor CXCR7 is essential for normal development, and this receptor promotes initiation and progression of diseases including cancer and autoimmunity. To understand normal and pathologic functions of CXCR7 and advance development of therapeutic agents, there is a need to define structural domains that regulate this receptor. We generated mutants of CXCR7 with deletion of different lengths of the predicted intracellular tail and analyzed effects on CXCR7 signaling and function in cell-based assays. While wild-type CXCR7 predominantly localized to intracellular vesicles, progressive deletion of the carboxy terminus redistributed the receptor to the plasma membrane. Truncating the intracellular tail of CXCR7 did not alter binding to CXCL12, but mutant receptors had reduced scavenging of this chemokine. Using a firefly luciferase complementation system, we established that deletions of the carboxy terminus decreased basal interactions and eliminated ligand-dependent recruitment of the scaffolding protein ß-arrestin-2 to receptors. Deleting the carboxy terminus of CXCR7 impaired constitutive internalization of the receptor and reduced activation of ERK1/2 by CXCL12-CXCR7. Inhibiting dynamin, a molecule required for internalization of CXCR7, increased ligand-dependent association of the receptor with ß-arrestin-2 and enhanced activation of ERK1/2. These studies establish mechanisms of action for CXCR7 and establish the intracellular tail of CXCR7 as a critical determinant of receptor trafficking, chemokine scavenging, and signaling.