P.234 “Inappropriate” spinal ultrasounds for suspected occult spinal dysraphism in northern Alberta

Background: Occult spinal dysraphism (OSD) may be associated with visible cutaneous manifestations. A common non-pathological mimic of a dermal sinus tract is an incidental sacrococcygeal dimple. Choosing Wisely Canada Guidelines recommend these dimples not be imaged. Methods: This study assessed the appropriateness of spinal ultrasounds performed for the investigation of an OSD. We interrogated our local imaging system to analyze spinal ultrasounds being performed in babies less than 6 months of age, from 2017-2018. Results: 429 children had spinal ultrasounds ordered by pediatricians (55%), family doctors (21%), and neonatologists (20%). 183 children (43%) had imaging indications that was deemed “inappropriate”. Some of this cohort had further MRI imaging (5/183) or neurosurgical referral (8/183). None of these children underwent neurosurgery. 231 (54%) children had appropriate indications for imaging. Within this cohort MRI imaging (23/231), neurosurgical referral (24/231) and neurosurgical intervention occurred (4/231). All four “surgical children” harboured either a dorsal appendage or a subcutaneous lipoma. We estimated, declining inappropriate scans would save $22, 500 annually. Conclusions: A significant portion of local spinal ultrasound requests for OSD are inappropriate. Collaboration with other sites is ongoing to investigate if the Choosing Wisely guidelines for imaging this patient population are being practiced more efficiently.

Detecting New Allies: Modifier Screen Identifies a Genetic Interaction Between Imaginal disc growth factor 3 and combover, a Rho-kinase Substrate, During Dorsal Appendage Tube Formation in Drosophila

Biological tube formation underlies organ development and, when disrupted, can cause severe birth defects. To investigate the genetic basis of tubulogenesis, we study the formation of Drosophila melanogaster eggshell structures, called dorsal appendages, which are produced by epithelial tubes. Previously we found that precise levels of Drosophila Chitinase-Like Proteins (CLPs), encoded by the Imaginal disc growth factor (Idgf) gene family, are needed to regulate dorsal-appendage tube closure and tube migration. To identify factors that act in the Idgf pathway, we developed a genetic modifier screen based on the finding that overexpressing Idgf3 causes dorsal appendage defects with ∼50% frequency. Using a library of partially overlapping heterozygous deficiencies, we scanned chromosome 3L and found regions that enhanced or suppressed the Idgf3-overexpression phenotype. Using smaller deletions, RNAi, and mutant alleles, we further mapped five regions and refined the interactions to 58 candidate genes. Importantly, mutant alleles identified combover (cmb), a substrate of Rho-kinase (Rok) and a component of the Planar Cell Polarity (PCP) pathway, as an Idgf3-interacting gene: loss of function enhanced while gain of function suppressed the dorsal appendage defects. Since PCP drives cell intercalation in other systems, we asked if cmb/+ affected cell intercalation in our model, but we found no evidence of its involvement in this step. Instead, we found that loss of cmb dominantly enhanced tube defects associated with Idgf3 overexpression by expanding the apical area of dorsal appendage cells. Apical surface area determines tube volume and shape; in this way, Idgf3 and cmb regulate tube morphology.

Detecting new allies: Modifier screen identifies a genetic interaction between Imaginal disc growth factor 3 and a Rho-kinase substrate during dorsal appendage tube formation in Drosophila

ABSTRACTBiological tube formation underlies organ development, and when disrupted, can cause severe birth defects. To investigate the genetic basis of tubulogenesis, we study the formation of Drosophila melanogaster eggshell structures, called dorsal appendages, which are produced by epithelial tubes. Previously we found that precise levels of Drosophila Chitinase-like proteins (CLPs), encoded by the Imaginal disc growth factor (Idgf) gene family, are needed to regulate dorsal-appendage tube closure and tube migration. To identify factors that act in the Idgf pathway, we developed a genetic modifier screen based on the finding that overexpressing Idgf3 causes dorsal appendage defects with ∼50% frequency. Using a library of partially overlapping heterozygous deficiencies, we scanned chromosome 3L and found regions that enhanced or suppressed the Idgf3-overexpression phenotype. Using smaller deletions, RNAi, and mutant alleles, we further mapped five regions and refined the interactions to 58 candidate genes. Importantly, mutant alleles identified combover (cmb), a substrate of Rho-kinase (Rok) and a component of the Planar Cell Polarity (PCP) pathway, as an Idgf3-interacting gene: loss of function enhanced while gain of function suppressed the dorsal appendage defects. Since PCP drives cell intercalation in other systems, we asked if cmb/+ affected cell intercalation in our model, but we found no evidence of its involvement in this step. Instead, we found that loss of cmb dominantly enhanced tube defects associated with Idgf3 overexpression by expanding the apical area of dorsal appendage cells. Apical surface area determines tube volume and shape; in this way, Idgf3 and cmb regulate tube morphology.

A new species in the Rhyacophila lieftincki Group (Trichoptera: Rhyacophilidae) from southwestern Virginia

Members of the Rhyacophila lieftincki Group (Trichoptera: Rhyacophilidae) share distinctive characters in both the adult (Schmid 1970) and larval forms (Smith 1984). In males, segment IX is short ventrally, with the apico-dorsal portion forming a large, usually triangular lobe over segment X. Segment X is somewhat reduced in height, slightly oblique to the base, and bearing small, claw- or toothlike points at its posterior end. Anal sclerites are vestigial or lacking in about half the species, and usually without roots. The phallotheca and endotheca are reduced, and the dorsal appendage of the phallic apparatus is absent. In the larva, the anal proleg has an apicolateral spur that arises independently of the lateral sclerites. The anal claw has a comb-like row of minute teeth ventrally and tergite IX has anterolateral angles extended ventrally to near the sternum.