Factors favoring neck metastasis in patients underwent laryngectomy for laryngeal cancer

Background One third of all head and neck cancers are caused by laryngeal cancer. However, the incidence and prevalence rates have decreased over the past 3 decades. Neck metastasis from cancer larynx is important to be addressed as its presence greatly reduces the probability of survival. However, quality of life should be taken into consideration. Hence, it was important to analyze factors related to neck metastasis from primary laryngeal cancer to detect any change of tumor behavior with time. Results One hundred thirty-eight patients underwent concomitant neck dissection with laryngectomy (total or partial). Supraglottic tumors had the greatest share in the neck metastasis with a count of 11 (of 26 neck metastasis), representing 42% and a total value of 11 (of 30 total supraglottic cancer) representing a tendency of spread in 37% of the total case number. Tumor midline crossing was present in 77% cases (20 of 26) with positive nodes, representing a P value 0.05. Conclusion This study investigated different factors related to lymph node metastasis from primary laryngeal tumor. The most important factors were the site of the tumor and its relation to the midline.

DCC regulates astroglial development essential for telencephalic morphogenesis and corpus callosum formation

The forebrain hemispheres are predominantly separated during embryogenesis by the interhemispheric fissure (IHF). Radial astroglia remodel the IHF to form a continuous substrate between the hemispheres for midline crossing of the corpus callosum (CC) and hippocampal commissure (HC). DCC and NTN1 are molecules that have an evolutionarily conserved function in commissural axon guidance. The CC and HC are absent in Dcc and Ntn1 knockout mice, while other commissures are only partially affected, suggesting an additional aetiology in forebrain commissure formation. Here, we find that these molecules play a critical role in regulating astroglial development and IHF remodelling during CC and HC formation. Human subjects with DCC mutations display disrupted IHF remodelling associated with CC and HC malformations. Thus, axon guidance molecules such as DCC and NTN1 first regulate the formation of a midline substrate for dorsal commissures prior to their role in regulating axonal growth and guidance across it.

Robo recruitment of the Wave Regulatory Complex plays an essential and conserved role in midline repulsion

The Roundabout (Robo) guidance receptor family induces axon repulsion in response to its ligand Slit by inducing local cytoskeletal changes; however, the link to the cytoskeleton and the nature of these cytoskeletal changes are poorly understood. Here, we show that the heteropentameric Scar/Wave Regulatory Complex (WRC) which drives Arp2/3-induced branched actin polymerization, is a direct effector of Robo signaling. Biochemical evidence shows that Slit triggers WRC recruitment to the Robo receptor's WIRS motif. In Drosophila embryos, mutants of the WRC enhance Robo1-dependent midline crossing defects. Additionally, mutating Robo1's WIRS motif significantly reduces receptor activity in rescue assays in vivo, and CRISPR-Cas9 mutagenesis shows that the WIRS motif is essential for endogenous Robo1 function. Finally, axon guidance assays in mouse dorsal spinal commissural axons and gain-of-function experiments in chick embryos demonstrate that the WIRS motif is also required for Robo1 repulsion in mammals. Together, our data support an essential conserved role for the WIRS-WRC interaction in Robo1-mediated axon repulsion.

Conserved and divergent aspects of Robo receptor signaling and regulation between Drosophila Robo1 and C. elegans SAX-3

The evolutionarily conserved Roundabout (Robo) family of axon guidance receptors control midline crossing of axons in response to the midline repellant ligand Slit in bilaterian animals including insects, nematodes, and vertebrates. Despite this strong evolutionary conservation, it is unclear whether the signaling mechanism(s) downstream of Robo receptors are similarly conserved. To directly compare midline repulsive signaling in Robo family members from different species, here we use a transgenic approach to express the Robo family receptor SAX-3 from the nematode Caenorhabditis elegans in neurons of the fruit fly, Drosophila melanogaster. We examine SAX-3’s ability to repel Drosophila axons from the Slit-expressing midline in gain of function assays, and test SAX-3’s ability to substitute for Drosophila Robo1 during fly embryonic development in genetic rescue experiments. We show that C. elegans SAX-3 is properly translated and localized to neuronal axons when expressed in the Drosophila embryonic CNS, and that SAX-3 can signal midline repulsion in Drosophila embryonic neurons, although not as efficiently as Drosophila Robo1. Using a series of Robo1/SAX-3 chimeras, we show that the SAX-3 cytoplasmic domain can signal midline repulsion to the same extent as Robo1 when combined with the Robo1 ectodomain. We show that SAX-3 is not subject to endosomal sorting by the negative regulator Commissureless (Comm) in Drosophila neurons in vivo, and that peri-membrane and ectodomain sequences are both required for Comm sorting of Drosophila Robo1.

A telehealth system incorporating a serious game intervention to aid occupational therapists identify and treat children with midline crossing difficulties (Preprint)

BACKGROUND In order to overcome midline crossing difficulties, children require treatment from an occupational therapist. Due to the recent COVID-19 pandemic and resulting lockdowns, many children could not access occupational therapists, or had to decrease sessions. This puts additional pressure on parents or caretakers to assist children with interventions at home, or children do not get the needed treatment at all. This is challenging because caretakers are not qualified to handle this, and occupational therapists do not get adequate feedback on the child’s progress if home treatments do take place. OBJECTIVE Given that many children cannot visit occupational therapists as often, or at all, during various stages of the COVID-19 lockdowns, the first objective of this paper is to adapt a simple serious game into a telehealth solution. Children will play the game at home under the supervision of a caretaker or guardian and results are stored online. An online dashboard is generated where occupational therapists can monitor a child’s progress, get valuable additional feedback about the child’s behaviour during treatment and can easily change the variables of the game to target specific difficulties a child might experience. The second objective is to evaluate whether the implemented telehealth solution is feasible as a treatment option for midline crossing difficulties and thus fit for purpose. METHODS To meet the first objective, engineering and game development stakeholders formed a team with an occupational therapist and through a collaborative design process combined with an agile programming approach a telehealth solution was designed to assist remote monitoring of the serious game play. For the second objective, six different occupational therapists were introduced to the game, had the opportunity to play the game and then gave feedback during structured interviews. RESULTS A telehealth system was designed that makes use of different levels in the serious game, where each level addresses a different need of the therapy process. All results are saved online and occupational therapists can access a dashboard that will display the results of each child. Additionally, observed behavioural information will also be saved to assist the occupational therapist in making decisions regarding changes to the intervention. During the interviews, occupational therapists indicated that the dashboard will support their treatment plan and is indeed a feasible solution. CONCLUSIONS The telehealth solution, incorporating a serious game, is a feasible method to treat crossing the midline problems remotely. The therapists commented on the convenience of integrating both assessment and treatment into the same application as it assists the therapists when grading a child. The therapists collectively agreed that the quantitative aspect that the serious game creates by providing measurable and standardized data proves advantageous when compared to traditional methods of assessment and treatment.

SlitC-PlexinA1 mediates iterative inhibition for orderly passage of spinal commissural axons through the floor plate

Spinal commissural axon navigation across the midline in the floor plate requires repulsive forces from local Slit repellents. The long-held view is that Slits push growth cones forward and prevent them from turning back once they became sensitized to these cues after midline crossing. We analyzed with fluorescent reporters Slits distribution and FP glia morphology. We observed clusters of Slit-N and Slit-C fragments decorating a complex architecture of glial basal process ramifications. We found that PC2 proprotein convertase activity contributes to this pattern of ligands. Next, we studied Slit-C acting via PlexinA1 receptor shared with another FP repellent, the Semaphorin3B, through generation of a mouse model baring PlexinA1Y1815F mutation abrogating SlitC but not Sema3B responsiveness, manipulations in the chicken embryo, and ex vivo live imaging. This revealed a guidance mechanism by which SlitC constantly limits growth cone exploration, imposing ordered and forward-directed progression through aligned corridors formed by FP basal ramifications.

Differences of the midline-crossing venous drainage pattern in supraumbilical and infraumbilical regions: Angiographic study using fresh cadavers

Current clinical and anatomical studies show that the venous problem associated with the deep inferior epigastric perforator flap results from poor midline-crossing. We examined the venous anatomy of the infraumbilical midline area and the dynamic venous flow of the deep inferior epigastric perforator flap in nine fresh cadavers. All nine abdominal specimens were harvested between the subcostal margin and the groin crease. Two specimens were used to analyze the abdominal venous anatomy, one of which was divided into two hemi-abdominal specimens. The remaining seven specimens were harvested as deep inferior epigastric perforator flaps with one major paraumbilical perforator. Venous cannulation and serial angiographic agent injection were performed in several conditions. Each specimen was radiographed using a soft X-ray system. For additional information, computed tomography (CT) angiography-visualized superficial inferior epigastric veins (SIEVs) and the supraumbilical branch were analyzed. We noted that the venous drainage between the bilateral SIEVs was easier to configure in the supraumbilical area than in the infraumbilical area. Only one to two short polygonal venous networks connect the bilateral superficial inferior epigastric veins in the supraumbilical area; however, long and multiple polygonal venous networks connect the bilateral superficial inferior epigastric veins in the infraumbilical area, which could be a predisposing factor for venous congestion. The mean distance from the umbilicus upper border to evident supraumbilical midline crossover was 18.39±4.03 mm (range: 10.10–28.49) in CT angiograms. In cadaver specimens, the mean distance was 10.87±4.85 mm (range: 4.6–18.9). Supraumbilical midline crossover was more favorable than infraumbilical midline crossover in venous flow.

Robo recruitment of the Wave Regulatory Complex plays an essential and conserved role in midline repulsion

SUMMARYThe Roundabout (Robo) guidance receptor family induces axon repulsion in response to its ligand Slit by inducing local cytoskeletal changes; however, the link to the cytoskeleton and the nature of these cytoskeletal changes are unclear. Here we show that the heteropentameric Scar/Wave Regulatory Complex (WRC) which drives Arp2/3-induced branched actin polymerization, is a direct effector of Robo signaling. Biochemical evidence shows that Slit triggers WRC recruitment to the Robo receptor’s WIRS motif. In Drosophila embryos, mutants of the WRC enhance Robol-dependent midline crossing defects. Additionally, mutating Robo1’s WIRS motif significantly reduces receptor activity in rescue assays in vivo, and CRISPR-Cas9 mutagenesis shows that the WIRS motif is essential for endogenous Robo1 function. Finally, axon guidance assays in mouse dorsal spinal commissural axons demonstrate that the WIRS motif is also required for Robo1 repulsion in mammals. Together, our data support an essential conserved role for the WRC in commissural axon repulsion.

teiresias, a Fruitless target gene encoding an immunoglobulin-superfamily transmembrane protein, is required for neuronal feminization in Drosophila

This study aims at identifying transcriptional targets of FruitlessBM (FruBM), which represents the major isoform of male-specific FruM transcription factors that induce neural sexual dimorphisms. A promoter of the axon-guidance factor gene robo1 carries the 16-bp palindrome motif Pal1, to which FruM binds. Our genome-wide search for Pal1-homologous sequences yielded ~200 candidate genes. Among these, CG17716 potentially encodes a transmembrane protein with extracellular immunoglobulin (Ig)-like domains similar to Robo1. Indeed, FruBM overexpression reduced CG17716 mRNA and protein expression. In the fru-expressing mAL neuron cluster exhibiting sexual dimorphism, we found that CG17716 knockdown in female neurons completely transformed all neurites to the male-type. Conversely, CG17716 overexpression suppressed male-specific midline crossing of fru-expressing sensory axons. We renamed CG17716 teiresias (tei) based on this feminizing function. We hypothesize that Tei interacts with other Ig superfamily transmembrane proteins, including Robo1, to feminize the neurite patterns in females, whereas FruBM represses tei transcription in males.