Pigmentary retinal dystrophy and the syndrome of maternally inherited diabetes and deafness caused by the mitochondrial DNA 3243 tRNA(Leu) A to G mutation.

OBJECTIVE: To study the association of retinal disease and the syndrome of maternally inherited diabetes and deafness caused by an A to G mutation in the tRNA leucine gene at base pair 3243 (A3243G) of the mitochondrial genome. DESIGN: Observational study of a genetically defined subject group. PARTICIPANTS: Thirteen subjects with the mitochondrial DNA A3243G mutation from seven different pedigrees with maternally inherited diabetes and deafness. INTERVENTION: Assessment of visual symptoms and visual acuity, dilated indirect ophthalmoscopy, retinal photography, and retinal electrophysiology. MAIN OUTCOME MEASURES: Loss of vision, funduscopic evidence of pigmentary retinal disease or diabetic retinopathy, and electrophysiologic evidence of defective functioning of the retinal pigment epithelium/photoreceptor complex. RESULTS: Funduscopic examination revealed abnormalities of retinal pigmentation in ten subjects (77%). Defects included speckled and patchy hyperpigmentation at the posterior pole of the fundus, particularly in the macular area, and varying degrees of loss of retinal pigmentation. Three subjects (23%) had visual symptoms, which included night blindness, visual loss, and photophobia. Electrophysiologic studies revealed impaired electro-oculogram responses in four of nine subjects with defects of retinal pigmentation (44%), two of whom also had much reduced scotopic and, to a lesser extent, flicker electroretinogram b wave potentials. Two subjects had diabetic retinopathy, including one with retinal depigmentation and impaired electro-oculogram activity. Both subjects with diabetic retinopathy had unilateral reduced electroretinogram responses, especially oscillatory potentials. CONCLUSIONS: Abnormalities of retinal pigmentation are common in subjects with maternally inherited diabetes and deafness caused by the mitochondrial DNA A3243G mutation. Visual symptoms, in particular loss of visual acuity, appear to be infrequent. The combination of deficits in the electro-oculogram and scotopic and flicker electroretinograms suggests that the retinal dystrophy includes defective functioning of retinal pigment epithelial cells and of both rod and cone photoreceptors. The pigmentary retinopathy does not prevent diabetic retinopathy; a single subject had funduscopic and electrophysiologic evidence of both diseases. Current evidence suggests that the mitochondrial DNA A3243G mutation accounts for 0.5% to 2.8% of diabetes. Most ophthalmic and diabetic clinics are therefore likely to contain such patients, who may benefit from identification of the genetic defect causing their disease and from genetic counseling.     

Novel Small Molecule Glucagon-Like Peptide-1 Receptor Agonist Stimulates Insulin Secretion in Rodents and From Human Islets

OBJECTIVE

The clinical effectiveness of parenterally-administered glucagon-like peptide-1 (GLP-1) mimetics to improve glucose control in patients suffering from type 2 diabetes strongly supports discovery pursuits aimed at identifying and developing orally active, small molecule GLP-1 receptor agonists. The purpose of these studies was to identify and characterize novel nonpeptide agonists of the GLP-1 receptor.

RESEARCH DESIGN AND METHODS

Screening using cells expressing the GLP-1 receptor and insulin secretion assays with rodent and human islets were used to identify novel molecules. The intravenous glucose tolerance test (IVGTT) and hyperglycemic clamp characterized the insulinotropic effects of compounds in vivo.

RESULTS

Novel low molecular weight pyrimidine-based compounds that activate the GLP-1 receptor and stimulate glucose-dependent insulin secretion are described. These molecules induce GLP-1 receptor-mediated cAMP signaling in HEK293 cells expressing the GLP-1 receptor and increase insulin secretion from rodent islets in a dose-dependent manner. The compounds activate GLP-1 receptor signaling, both alone or in an additive fashion when combined with the endogenous GLP-1 peptide; however, these agonists do not compete with radiolabeled GLP-1 in receptor-binding assays. In vivo studies using the IVGTT and the hyperglycemic clamp in Sprague Dawley rats demonstrate increased insulin secretion in compound-treated animals. Further, perifusion assays with human islets isolated from a donor with type 2 diabetes show near-normalization of insulin secretion upon compound treatment.

CONCLUSIONS

These studies characterize the insulinotropic effects of an early-stage, small molecule GLP-1 receptor agonist and provide compelling evidence to support pharmaceutical optimization.Hyperglucagonemia and dysregulation of insulin secretion impair postprandial glucose homeostasis and thus are central to the pathogenesis of type 2 diabetes. Impairment of the incretin effect, including reduced secretion of glucagon-like peptide-1 (GLP-1) (1,2), is implicated in the progression of pancreatic islet dysfunction in type 2 diabetic patients. Development and use of incretin-based therapeutics may, therefore, be an effective strategy to restore normal islet function by providing insulinotropic and glucagon-suppressive capabilities. In recent years, clinical studies have shown that replacement therapy with metabolically stable GLP-1 mimetics greatly improves management of hyperglycemia, nearly correcting blood glucose regulation for some patients. For example, treatment with either exenatide or liraglutide reduces fasting hyperglycemia and results in sustained lowering of glycosylated A1C (A1C) levels (3,4). In addition, these therapies often reduce body weight and improve several cardiovascular parameters (5,6). Unfortunately, both of these GLP-1 analogues are peptides requiring administration by subcutaneous injection.The GLP-1 receptor is a member of the class B/II family of seven transmembrane G protein-coupled receptors (GPCRs) that include receptors for peptide hormones such as secretin, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucagon, vasoactive intestinal peptide (VIP), corticotropin-releasing factor (CRF), calcitonin, and parathyroid hormone (PTH) (7–9). Historically, the discovery of nonpeptide agonists of these receptors that could enable development of orally active pharmaceuticals has been generally unsuccessful. To a large extent, this difficulty has been attributed to the mechanisms used by class B GPCRs to recognize ligands and induce signaling. Interaction of endogenous peptide hormones with their receptors typically involves large receptor:ligand binding sites and is often initiated by receptor NH₂-terminal ectodomains (ECDs). This extracellular structure interacts with COOH-terminal residues of cognate ligands and positions the NH₂-terminus of the ligand to interact with critical determinants in receptor transmembrane regions, thereby activating heterotrimeric G-proteins and subsequently adenylyl cyclase (10–12).The recent reports describing GLP-1 receptor activation by a series of substituted quinoxalines (13–16) and a cyclobutane derivative (17) suggest that it may be possible to develop nonpeptide GLP-1 receptor agonists. Both scaffolds activate GLP-1 receptor signaling in heterologous GLP-1 receptor-expressing cellular systems, and the quinoxalines clearly induce glucose-stimulated insulin secretion in vitro from rodent islets and ex vivo via perfused pancreas (13,16). We now report novel, low molecular weight pyrimidines that activate the GLP-1 receptor to induce glucose-dependent insulin secretion both in vitro and in vivo. These molecules may offer therapeutic advantage because of the ability of the compounds to act alone or in combination with GLP-1. Further, these agonists nearly restore insulin secretion to normal in human diabetic islets.     

Aquaporin-4 autoantibodies in neuromyelitis optica spectrum disorders: comparison between tissue-based and cell-based indirect immunofluorescence assays

Background  

Neuromyelitis optica spectrum disorders (NMOSD) are severe central nervous system inflammatory demyelinating disorders (CNS IDD) characterized by monophasic or relapsing, longitudinally extensive transverse myelitis (LETM) and/or optic neuritis (ON). A significant proportion of NMOSD patients are seropositive for aquaporin-4 (AQP4) autoantibodies. We compared the AQP4 autoantibody detection rates of tissue-based indirect immunofluorescence assay (IIFA) and cell-based IIFA.     

Adjuvant radiotherapy and survival outcomes in early-stage endometrial cancer: a multi-institutional analysis of 608 women

OBJECTIVE: The role of post-operative radiotherapy (RT) in women with early-stage, low to intermediate risk cancer of the uterine corpus remains controversial. The primary objective of this analysis was to evaluate the survival outcomes of women with early-stage endometrial cancer treated with surgery alone or surgery followed by RT. METHODS: Data from two institutions were collected from 1990 to 2003. The 608 eligible women had FIGO stage IA to IIA endometrial cancer and underwent primary surgery +/-RT. Univariate and multivariate analyses of pertinent variables were performed for the end points of disease-free survival (DFS) and overall survival (OS). RESULTS: The median age for all women was 64 years. RT was delivered to 133 women (22%). Unfavorable histologic grade (P < 0.0001) and stage (P < 0.0001) were significantly more prevalent in the adjuvant RT group. At a median follow-up of 5.2 years, 26 pelvic (11 vaginal) and 16 distant failures occurred along with 110 deaths (with no significant differences between women undergoing surgery alone or followed by RT). Adjuvant RT, younger age, and lower stage predicted for improved DFS and OS on multivariate analysis. Stratified analysis revealed that adjuvant RT conferred a survival benefit in women with stage IC or IIA disease. CONCLUSIONS: Adjuvant RT was associated with improved disease-free and overall survival in women with higher risk disease. Despite significantly worse disease characteristics among women in the adjuvant RT group, the analyzed end points were equivalent among the two groups. These findings suggest that adjuvant radiotherapy has a significant benefit in reducing mortality and disease progression in early-stage carcinoma of the uterine corpus.     

Genetic and epigenetic loss of microRNA-31 leads to feed-forward expression of EZH2 in melanoma

MicroRNAs (miRs) play a key role in cancer etiology by coordinately repressing numerous target genes involved in cell proliferation, migration and invasion. The genomic region in chromosome 9p21 that encompasses miR-31 is frequently deleted in solid cancers including melanoma; however the expression and functional role of miR-31 has not been previously studied in melanoma. Here, we queried the expression status and performed functional characterization of miR-31 in melanoma tissues and cell lines. We found that down-regulation of miR-31 was a common event in melanoma tumors and cell lines and was associated with genomic loss in a subset of samples. Down-regulation of miR-31 gene expression was also a result of epigenetic silencing by DNA methylation, and via EZH2-mediated histone methylation. Ectopic overexpression of miR-31 in various melanoma cell lines inhibited cell migration and invasion. miR-31 targets include oncogenic kinases such as SRC, MET, NIK (MAP3K14) and the melanoma specific oncogene RAB27a. Furthermore, miR-31 overexpression resulted in down-regulation of EZH2 and a de-repression of its target gene rap1GAP; increased expression of EZH2 was associated with melanoma progression and overall patient survival. Taken together, our study supports a tumor suppressor role for miR-31 in melanoma and identifies novel therapeutic targets.     

Adjuvant radiation in early stage,unfavorable histology endometrial carcinoma is associated with improved local control and survival

Objective

Unfavorable histology endometrial carcinomas confer worse prognosis. We determined the association of adjuvant radiation on local recurrence and survival for unfavorable, early stage endometrial cancer.

Methods

We retrospectively identified 125 patients who had a hysterectomy for early stage (FIGO IA), unfavorable histology (clear cell, papillary serous or grade 3 endometrioid), endometrial carcinoma treated between 1992 and 2011. Patients were restaged according to current FIGO 2009 guidelines. Primary endpoint was local control and secondary endpoints were distant recurrence and overall survival.

Results

The median age of the cohort was 67 years old with a mean follow up 152 months. Adjuvant radiation was delivered in 60 patients (48%). There were a total of 24 recurrences; 5 had local–regional recurrences, 4 local and distant recurrence, 12 distant only recurrences, and 3 had unspecified recurrences. The 5-year local–regional control was 97.8% in patients who received radiation and 80.1% in patients who did not receive radiation (p = 0.018). The 5-year overall survival rate was 68.1% if patients did not receive radiation and 84.9% if they did receive radiation (p = 0.0062). On univariate analysis, only radiation (HR 0.12, 95% CI: 0.03 to 0.49, p-value = 0.018) was associated with a significant increase in local relapse free survival.

Conclusions

Adjuvant radiation therapy was significantly associated with an improvement in local–regional control and overall survival in patients with unfavorable histology, early stage endometrial cancer.     

Pain response and follow-up of patients undergoing panretinal laser photocoagulation with reduced exposure times

PURPOSE: We performed a study of laser panretinal photocoagulation in 20 patients with proliferative retinopathy. We compared short exposure, high-energy laser settings with conventional settings, using a 532 nm, frequency doubled, Neodymium-Yag laser and assessed the patients in terms of pain experienced and effectiveness of treatment. METHODS: Twenty patients having panretinal photocoagulation for the first time underwent random allocation to treatment of the superior and inferior hemi-retina. Treatment A used 'conventional' parameters: exposure time 0.1 s, power sufficient to produce a visible grey-white burns, spot size 300 microm. The other hemi- retina was treated with treatment B using exposure 0.02 s, 300 microm and sufficient power to have similar endpoint. All patients were asked to evaluate severity of pain on a visual analogue scale. (0=no pain, 10=most severe pain). All patients were masked as to the type of treatment and the order of carrying out the treatment on each patient was randomised. Patients underwent fundus photography and were followed up for 6-45 months. RESULTS: Seventeen patients had proliferative diabetic retinopathy, two had ischaemic central retinal vein occlusion and one had ocular ischaemic syndrome. The mean response to treatment A was 5.11, compared to 1.40 treatment B, on the visual analogue scale, which was statistically significant (P=0.001). All patients preferred treatment B. Further treatments, if required, were performed with treatment B parameters and long-term follow-up has shown no evidence of undertreatment. CONCLUSIONS: Shortening exposure time of retinal laser is significantly less painful but equally effective as conventional parameters.