Complimentary action of structured and unstructured domains of epsin supports clathrin-mediated endocytosis at high tension.

Membrane tension plays an inhibitory role in clathrin-mediated endocytosis (CME) by impeding the transition of flat plasma membrane to hemispherical clathrin-coated structures (CCSs). Membrane tension also impedes the transition of hemispherical domes to omega-shaped CCSs. However, CME is not completely halted in cells under high tension conditions. Here we find that epsin, a membrane bending protein which inserts its N-terminus H0 helix into lipid bilayer, supports flat-to-dome transition of a CCS and stabilizes its curvature at high tension. This discovery is supported by molecular dynamic simulation of the epsin N-terminal homology (ENTH) domain that becomes more structured when embedded in a lipid bilayer. In addition, epsin has an intrinsically disordered protein (IDP) C-terminus domain which induces membrane curvature via steric repulsion. Insertion of H0 helix into lipid bilayer is not sufficient for stable epsin recruitment. Epsin's binding to adaptor protein 2 and clathrin is critical for epsin's association with CCSs under high tension conditions, supporting the importance of multivalent interactions in CCSs. Together, our results support a model where the ENTH and unstructured IDP region of epsin have complementary roles to ensure CME initiation and CCS maturation are unimpeded under high tension environments.

False negative sentinel lymph node biopsies in melanoma may result from deficiencies in nuclear medicine, surgery, or pathology.

OBJECTIVE: To investigate a cohort of melanoma patients with false negative (FN) sentinel node (SN) biopsies (SNBs) to identify the reasons for the FN result. SUMMARY OF BACKGROUND DATA: SNB is a highly efficient staging method in melanoma patients. However, with long-term follow-up FN SNB results of up to 25% have been reported. METHODS: Seventy-four SNs from 33 patients found to have had an FN SNB were analyzed by reviewing the lymphoscintigraphy, surgical data, and histopathology, and by assessing nodal tissue using multimarker real-time quantitative reverse transcription (qRT) polymerase chain reaction, and antimony concentration measurements (as a marker of "true" SN status) using inductively coupled plasma mass spectroscopy. RESULTS: Nine SNs (12%) from 9 patients (27%) had evidence of melanoma on histopathologic review. Twelve SNs (16%) from 10 patients (30%) were qRT(+). Four of these 12 SNs were positive on histopathology review and 8 were negative. Four patients (12%) were upstaged by qRT. Sixteen patients had their SNB histology, lymphoscintigraphy, and surgical data reviewed. Identifiable causes of the FN SNBs were not found after review of all modalities in 4 patients. SNs from all 4 patients had antimony levels indicative of an SN. Of the SNs evaluable by qRT, 1 was qRT(+) and 7 SNs from 2 patients were qRT(-). CONCLUSIONS: An FN SN can occur because of deficiencies in nuclear medicine, surgery, or pathology. qRT can detect "occult" metastatic melanoma in SNs that have been identified as negative by histopathology.

The Caenorhabditis elegans Ephrin EFN-4 Functions Non-cell Autonomously with Heparan Sulfate Proteoglycans to Promote Axon Outgrowth and Branching.

The Eph receptors and their cognate ephrin ligands play key roles in many aspects of nervous system development. These interactions typically occur within an individual tissue type, serving either to guide axons to their terminal targets or to define boundaries between the rhombomeres of the hindbrain. We have identified a novel role for the Caenorhabditis elegans ephrin EFN-4 in promoting primary neurite outgrowth in AIY interneurons and D-class motor neurons. Rescue experiments reveal that EFN-4 functions non-cell autonomously in the epidermis to promote primary neurite outgrowth. We also find that EFN-4 plays a role in promoting ectopic axon branching in a C. elegans model of X-linked Kallmann syndrome. In this context, EFN-4 functions non-cell autonomously in the body-wall muscle and in parallel with HS modification genes and HSPG core proteins. This is the first report of an epidermal ephrin providing a developmental cue to the nervous system.

Variation in the diagnosis, treatment, and management of melanoma in situ: a survey of US dermatologists.

OBJECTIVE: To assess current practices of US dermatologists regarding the diagnosis, treatment, and management of melanoma in situ (MIS). DESIGN: Survey. PARTICIPANTS: A total of 1200 dermatologists randomly selected from the American Board of Medical Specialists Directory of Board Certified Medical Specialists. MAIN OUTCOME MEASURES: Results based on 597 questionnaires returned. RESULTS: The overall response rate was 63% (597 of 945 eligible participants). To aid in clinical assessment, respondents reported using a magnifying lens (57.4%) and dermoscopy (17.4%). Most dermatologists preferred excisional and saucerization biopsies as the method of choice for sampling. A large percentage of physicians (78.9%) preferentially used dermatopathologists for the evaluation of the majority of pigmented lesions. Although most respondents would not unquestioningly accept a benign pathology diagnosis when there was a clinical suspicion of MIS, 16.1% would accept a pathologist's diagnosis without further action. There was no consensus on the appropriate surgical margins or depth of excision for MIS. Of the respondents who characterized MIS as premalignant and malignant, 63.2% and 46.4%, respectively, did not know what percentage of MISs would progress to metastatic disease if left untreated. CONCLUSIONS: Considerable variability exists in the clinical concept and management of MIS. Dermoscopy is underutilized. The true nature of the evolution of MIS is unknown. Surgical margins and depth of excision need to be standardized to help dermatologists manage disease. Further research in the specific area of MIS is warranted to develop clear guidelines in the management and prevention of further disease.

Outcome in 846 cutaneous melanoma patients from a single center after a negative sentinel node biopsy.

BACKGROUND: A negative sentinel node biopsy (SNB) implies a good prognosis for melanoma patients. The purpose of this study was to determine the long-term outcome for melanoma patients with a negative SNB. METHODS: Survival and prognostic factors were analyzed for 836 SNB-negative patients. All patients with a node field recurrence were reviewed, and sentinel node (SN) tissue was reexamined. RESULTS: The median tumor thickness was 1.7 mm, and 23.8% were ulcerated. The median follow-up was 42.1 months. Melanoma specific survival at 5 years was 90%, compared with 56% for SN-positive patients (P < .001). On multivariate analysis, only thickness and ulceration retained significance for disease-free and disease-specific survival. Five-year survival for patients with nonulcerated lesions was 94% vs. 78% with ulceration. Eighty-three patients (9.9%) had a recurrence. Twenty-seven patients developed recurrence in the regional node field, and in 22 of these, it was the first recurrence site. Six developed local recurrence, 17 an in-transit metastasis, and 58 distant disease. The false-negative rate was 13.2%. SN slides and tissue blocks were further examined in 18 patients with recurrence in the node field, and metastatic disease was found in 3 of them. CONCLUSIONS: This large, single-center study confirms that patients with a negative SNB have a significantly better prognosis than those with positive SNs. In those with a negative SNB, primary tumor thickness and ulceration are independent predictors of survival. Incorrect pathologic diagnosis contributed to only a minority of the false-negative results in this study.