A Feeding-Related Mechanoreceptor Identified in the Crab Cancer borealis Shares Similarities and Differences with Homologs in Other Crustaceans.

AbstractSensory feedback plays an essential role in shaping rhythmic animal movements. In the crustacean stomatogastric nervous system, which is responsible for grinding and filtering food particles in the animal's foregut, a number of mechanoreceptors whose activity affects motor output have been characterized. The hepatopancreas duct receptor neurons, which are located in the pyloric region of the foregut that is responsible for filtering, are among the less well understood groups of stomatogastric mechanoreceptors. Although they were first described decades ago in a number of decapod species, many questions remain about their role in shaping the movements produced by the stomatogastric nervous system. Here we provide the first anatomical and physiological evidence that there are also hepatopancreas duct receptors in the crab Cancer borealis, and we demonstrate that hepatopancreas duct receptor spiking produced by mechanical stimulation modifies the properties of an ongoing pyloric motor program.

Uveal melanoma patient attitudes towards prognostic testing using gene expression profiling.

Aim: This study explored uveal melanoma patient experiences and regret following molecular prognostic testing using a 15-gene expression profile (GEP) test. Materials & methods: A retrospective, cross-sectional survey study was conducted through an online questionnaire capturing patient-reported experiences with prognostic biopsy/molecular testing. Results: Of 177 respondents, 159 (90%) wanted prognostic information at diagnosis. Most 15-GEP-tested patients who shared their results (99%) reported gaining value from testing, as did patients tested with other methods. Patients who received prognostic testing experienced lower decision regret than those who opted out. Decision regret did not differ based on GEP class. Conclusion: Most uveal melanoma patients desire prognostic testing and gain value from the GEP, independent of a high- or low-risk result.

Uveal melanoma is a rare but aggressive eye cancer, resulting in distant metastasis in nearly 50% of patients. Molecular prognostic testing is often employed to determine who is at high or low risk of developing metastatic disease. A prognostic 15-gene expression profiling (GEP) test is commonly used throughout the USA and parts of Canada. The goal of this survey was to assess patient experiences with the 15-GEP and other prognostic methods. Of the 177 patients who participated in the survey, the majority reported that they wanted prognostic information at the time of diagnosis. Of patients who underwent 15-GEP testing, nearly all reported gaining value from their test result, regardless of their individual risk profile. This study supports prior findings using other prognostic methods that patients prefer information about their risk of metastasis and reinforces the importance of discussing prognostic testing options with newly diagnosed uveal melanoma patients.

Cystoid macular edema precipitated by altitude in a patient with X-linked retinitis pigmentosa.

BACKGROUND: X-linked retinitis pigmentosa (XLRP) is a hereditary retinopathy that may present with cystoid macular edema (CME). The exact cause of CME in XLRP is unknown. We describe a case report of new-onset CME precipitated by travel to high altitude in an adult with XLRP, but no known prior history of CME. CASE DESCRIPTION: A 38-year-old man with XLRP caused by a hemizygous pathogenic variant in RPGR (c.372del; p.Glu125fs) reported sudden onset bilateral blurry vision 4 days after ascending to an altitude of 3,700 m. He sought local ophthalmic care and was found to have severe bilateral CME. He was treated with topical and oral carbonic anhydrase inhibition and instructed to return to normal altitude. Follow-up imaging at normal altitude revealed that the CME was nearly completely resolved 4 days after initial presentation, and completely resolved 2 weeks after initial presentation. CONCLUSION: Vascular and metabolic changes caused by retinal degeneration in XLRP may predispose to the development of CME under the hypoxic conditions experienced at high altitudes. We advise that retinal specialists treating patients with RP should caution them on traveling to high altitudes that could precipitate or exacerbate CME.

Collaborative Ocular Oncology Group report number 1: prospective validation of a multi-gene prognostic assay in uveal melanoma.

PURPOSE: This study evaluates the prognostic performance of a 15 gene expression profiling (GEP) assay that assigns primary posterior uveal melanomas to prognostic subgroups: class 1 (low metastatic risk) and class 2 (high metastatic risk). DESIGN: Prospective, multicenter study. PARTICIPANTS: A total of 459 patients with posterior uveal melanoma were enrolled from 12 independent centers. TESTING: Tumors were classified by GEP as class 1 or class 2. The first 260 samples were also analyzed for chromosome 3 status using a single nucleotide polymorphism assay. Net reclassification improvement analysis was performed to compare the prognostic accuracy of GEP with the 7th edition clinical Tumor-Node-Metastasis (TNM) classification and chromosome 3 status. MAIN OUTCOME MEASURES: Patients were managed for their primary tumor and monitored for metastasis. RESULTS: The GEP assay successfully classified 446 of 459 cases (97.2%). The GEP was class 1 in 276 cases (61.9%) and class 2 in 170 cases (38.1%). Median follow-up was 17.4 months (mean, 18.0 months). Metastasis was detected in 3 class 1 cases (1.1%) and 44 class 2 cases (25.9%) (log-rank test, P<10(-14)). Although there was an association between GEP class 2 and monosomy 3 (Fisher exact test, P<0.0001), 54 of 260 tumors (20.8%) were discordant for GEP and chromosome 3 status, among which GEP demonstrated superior prognostic accuracy (log-rank test, P = 0.0001). By using multivariate Cox modeling, GEP class had a stronger independent association with metastasis than any other prognostic factor (P<0.0001). Chromosome 3 status did not contribute additional prognostic information that was independent of GEP (P = 0.2). At 3 years follow-up, the net reclassification improvement of GEP over TNM classification was 0.43 (P = 0.001) and 0.38 (P = 0.004) over chromosome 3 status. CONCLUSIONS: The GEP assay had a high technical success rate and was the most accurate prognostic marker among all of the factors analyzed. The GEP provided a highly significant improvement in prognostic accuracy over clinical TNM classification and chromosome 3 status. Chromosome 3 status did not provide prognostic information that was independent of GEP.

Germline BAP1 mutation predisposes to uveal melanoma, lung adenocarcinoma, meningioma, and other cancers.

OBJECTIVE: To investigate the potential contribution of germline sequence alterations in the BAP1 gene in uveal melanoma (UM) patients with possible predisposition to hereditary cancer. DESIGN: A total of 53 unrelated UM patients with high risk for hereditary cancer and five additional family members of one proband were studied. Mutational screening was carried out by direct sequencing. RESULTS: Of the 53 UM patients studied, a single patient was identified with a germline BAP1 truncating mutation, c. 799 C→T (p.Q267X), which segregated in several family members and was associated with UM and other cancers. Biallelic inactivation of BAP1 and decreased BAP1 expression were identified in the UM, lung adenocarcinoma and meningioma tumours from three family members with this germline BAP1 mutation. Germline BAP1 variants of uncertain significance, likely non-pathogenic, were also identified in two additional UM patients. CONCLUSION: This study reports a novel hereditary cancer syndrome caused by a germline BAP1 mutation that predisposes patients to UM, lung carcinoma, meningioma, and possibly other cancers. The results indicate that BAP1 is the candidate gene in only a small subset of hereditary UM, suggesting the contribution of other candidate genes.

Growth factors outside the PDGF family drive experimental PVR.

PURPOSE: Proliferative vitreoretinopathy (PVR) is a recurring and problematic disease for which there is no pharmacologic treatment. Platelet-derived growth factor (PDGF) in the vitreous is associated with experimental and clinical PVR. Furthermore, PDGF receptors (PDGFRs) are present and activated in epiretinal membranes of patient donors, and they are essential for experimental PVR. These observations suggest that PVR arises at least in part from PDGF/PDGFR-driven events. The goal of this study was to determine whether PDGFs were a potential therapeutic target for PVR. METHODS: Experimental PVR was induced in rabbits by injecting fibroblasts. Vitreous specimens were collected from experimental rabbits or from patients undergoing vitrectomy to repair retinal detachment. A neutralizing PDGF antibody and a PDGF Trap were tested for their ability to prevent experimental PVR. Activation of PDGFR was monitored by antiphosphotyrosine Western blot analysis of immunoprecipitated PDGFRs. Contraction of collagen gels was monitored in vitro. RESULTS: Neutralizing vitreal PDGFs did not effectively attenuate PVR, even though the reagents used potently blocked PDGF-dependent activation of the PDGF alpha receptor (PDGFRalpha). Vitreal growth factors outside the PDGF family modestly activated PDGFRalpha and appeared to do so without engaging the ligand-binding domain of PDGFRalpha. This indirect route to activate PDGFRalpha had profound functional consequences. It promoted the contraction of collagen gels and appeared sufficient to drive experimental PVR. CONCLUSIONS: Although PDGF appears to be a poor therapeutic target, PDGFRalpha is particularly attractive because it can be activated by a much larger spectrum of vitreal growth factors than previously appreciated.

Plasmin is the major protease responsible for processing PDGF-C in the vitreous of patients with proliferative vitreoretinopathy.

PURPOSE: Proliferative vitreoretinopathy (PVR) is the primary cause of failure of retinal reattachment surgery. Growth factors such as platelet-derived growth factor (PDGF) are strongly associated with PVR. Of the five PDGF family members, PDGF-C predominates in the vitreous of experimental and clinical PVR. PDGF-C is secreted as a latent protein that requires proteolytic processing for activation. Although tissue plasminogen activator (tPA) is primarily responsible for processing PDGF-C in cultured cells, it constitutes a minority of the processing activity in the vitreous of experimental animals and in patients with PVR. Identifying the major PDGF-C processing protease was the purpose of this study. METHODS: The presence of serum proteins in the vitreous was detected by Coomassie blue staining and Western blotting. PDGF-C processing activity was detected in an in vitro processing assay using either native or recombinant PDGF-C as the substrate. Plasmin activity was blocked using alpha(2)-plasmin inhibitor. Phosphorylation of the PDGF receptor (PDGFR) was monitored by antiphosphotyrosine Western blotting. Vitreous specimens were collected from experimental rabbits or from patients undergoing vitrectomy to repair retinal detachment or for other reasons. RESULTS: A number of prominent serum proteins (albumin and IgG) were detected in the vitreous of all patients undergoing retinal surgery. The level of these proteins markedly increased in the vitreous of rabbits as they developed PVR. These observations suggested that serum-borne proteases are also likely to be present in the vitreous. Indeed, plasmin (a protease capable of processing PDGF-C) was present in the vitreous from PVR rabbits and retinal surgery patients. Plasmin was dramatically more effective than tPA in processing PDGF-C in an in vitro assay. Blocking plasmin activity eliminated most of the processing activity in the vitreous of patients and rabbits with PVR. CONCLUSIONS: Plasmin was the major PDGF-C processing protease in the vitreous of PVR rabbits and patients undergoing retinal surgery. Blocking plasmin prevented the generation of active PDGF-C, which is the major PDGF isoform relevant for PVR. These observations are the first report of an in vivo protease responsible for processing PDGF-C. In addition, plasmin was identified as a novel therapeutic target for patients with PVR.

A potential role for PDGF-C in experimental and clinical proliferative vitreoretinopathy.

PURPOSE: Proliferative vitreoretinopathy (PVR) is a disorder characterized by the formation of cellular membranes on both surfaces of the retina and within the vitreous cavity. It occurs in 5% to 10% of patients who undergo retinal reattachment surgery. In the rabbit model of the disease, the platelet-derived growth factor alpha receptor (PDGFRalpha) is dramatically more capable of promoting PVR than is closely related PDGFRbeta. To test the ligand hypothesis (i.e., that this phenomenon can be explained by a predominance of PDGFRalpha-specific ligands) this study was conducted to determine the profile of PDGF ligands expressed by cells that induce PVR and in the vitreous of rabbits that have PVR. In addition, we examined which PDGF isoforms were present in the vitreous of patients with PVR, to assess the relevance of the rabbit model to the clinical setting. METHODS: PDGF isoforms were detected and quantified by Western blot analysis and ELISA. An assay was performed of conditioned medium from mouse embryo fibroblasts expressing the PDGFRalpha (Falpha) and rabbit conjunctival fibroblasts (RCFs), both of which cause PVR in the experimental model, and from human retinal pigment epithelial cells (ARPE-19). Because PDGF-C is secreted in a latent form and must be proteolytically processed to become biologically active, a PDGF-C processing assay was established, and conditioned medium was tested from these cells lines, for processing activity. Vitreous specimens, from control and PVR rabbits and from patients undergoing vitrectomy surgery, either to repair retinal detachment or for other reasons, were also tested for PDGF isoforms and for PDGF-C processing activity. RESULTS: PDGF isoforms that activate PDGFRbeta (PDGF-B and -D) were either undetectable or were present at very low levels in all the samples tested. Relatively low levels of PDGF-A and -AB were detected, whereas PDGF-C was the predominant isoform. Falpha, RCFs, and ARPE-19 cells accumulated PDGF-C in the conditioned medium at an average rate of 2.0 +/- 0.2, 2.9 +/- 0.3, and 71.3 +/- 6.0 ng/mL per day, respectively. Although there was no detectable PDGF-C in the vitreous of control rabbits (n = 8), there was an average of 1784 +/- 1150 ng/mL latent PDGF-C in the vitreous from rabbits with PVR (n= 14). Of the patients with PVR, eight of nine contained PDGF-C (range, 50-1000 ng/mL). In contrast, PDGF-C was detected in only 1 of 16 of the patients without PVR. In both conditioned medium and vitreous samples, the latent (instead of the active) form of PDGF-C was detected, even though processing activity was present in all the samples tested. CONCLUSIONS: The predominance of PDGF isoforms that activate PDGFRalpha support the ligand hypothesis as an explanation of why PDGFRalpha is more capable of inducing PVR than is PDGFRbeta. Furthermore, the profile of PDGF isoforms observed in the rabbit model accurately reflected the clinical specimens from patients with PVR. Finally, these findings implicate one of the new PDGF family members as an important contributor to experimental and clinical PVR.

Genomic investigations of posterior uveal melanoma.

The specific genetic mechanisms responsible for the malignant behavior of uveal melanoma are not known. Unlike cutaneous melanoma, epidemiologic studies have not demonstrated a definitive germline form of uveal melanoma, though familial melanoma and racial predilections occur. Molecular cytogenetic characterization of uveal melanoma suggests that somatic deletions of chromosome 3 are associated with a worse prognosis. Microarray technology has been used to characterize uveal melanoma gene expression and may provide tests useful for determining prognosis. As an improved understanding of the cellular mechanisms used by uveal melanoma is gained, new opportunities to adapt or design therapeutic approaches may emerge.