A Carborane-Containing Fluorophore as a Stain of Cellular Lipid Droplets

The use of fluorescent markers and probes greatly enhances biological investigations but relies on the provision of an array of fluorophores with diverse properties. Herein we report a novel carborane-containing coumarin, 5, which is sufficiently lipophilic to localise in cellular lipid droplets. In non-polar solvents which show comparable polarities to those of a lipid environment, compound 5 exhibits a fluorescence quantum yield two orders of magnitude greater than found in aqueous solvents, adding a further degree of selectivity to lipid droplet imaging. Compound 5 can stain lipid droplets in ex vivo adipocytes as well as in cultured cells, and can be utilised in flow cytometry as well as confocal microscopy.

Development of novel N-3-bromoisoxazolin-5-yl substituted 2,3-benzodiazepines as noncompetitive AMPAR antagonists

In this work, we designed and synthesized novel N-3-bromoisoxazolin-5-yl substituted 2,3-benzodiazepines as noncompetitive AMPAR antagonists, with the aim that this heterocycle could establish favourable interactions with a putative binding pocket of the receptor, like the thiadiazole nucleus of GYKI 47409 does. Within this investigation, we identified some active molecules and, among these 2,3-benzodiazepines, 4c showed a much improved inhibitory potency as compared with unsubstituted 2,3-benzodiazepines.

Identification and characterization of RNA aptamers: A long aptamer blocks the AMPA receptor and a short aptamer blocks both AMPA and kainate receptors

AMPA and kainate receptors, along with NMDA receptors, represent different subtypes of glutamate ion channels. AMPA and kainate receptors share a high degree of sequence and structural similarities, and excessive activity of these receptors has been implicated in neurological diseases such as epilepsy. Therefore, blocking detrimental activity of both receptor types could be therapeutically beneficial. Here, we report the use of an in vitro evolution approach involving systematic evolution of ligands by exponential enrichment with a single AMPA receptor target (i.e. GluA1/2R) to isolate RNA aptamers that can potentially inhibit both AMPA and kainate receptors. A full-length or 101-nucleotide (nt) aptamer selectively inhibited GluA1/2R with a KI of ∼5 μm, along with GluA1 and GluA2 AMPA receptor subunits. Of note, its shorter version (55 nt) inhibited both AMPA and kainate receptors. In particular, this shorter aptamer blocked equally potently the activity of both the GluK1 and GluK2 kainate receptors. Using homologous binding and whole-cell recording assays, we found that an RNA aptamer most likely binds to the receptor's regulatory site and inhibits it noncompetitively. Our results suggest the potential of using a single receptor target to develop RNA aptamers with dual activity for effectively blocking both AMPA and kainate receptors.

A mechanistic investigation of thrombotic microangiopathy associated with IV abuse of Opana ER

Since 2012, a number of case reports have described the occurrence of thrombotic microangiopathy (TMA) following IV abuse of extended-release oxymorphone hydrochloride (Opana ER), an oral opioid for long-term treatment of chronic pain. Here, we present unique clinical features of 3 patients and investigate IV exposure to the tablet's inert ingredients as a possible causal mechanism. Guinea pigs were used as an animal model to understand the hematopathologic and nephrotoxic potential of the inert ingredient mixture (termed here as PEO+) which primarily contains high-molecular-weight polyethylene oxide (HMW PEO). Microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury were found in a group of 3 patients following recent injection of adulterated extended-release oxymorphone tablets. Varying degrees of cardiac involvement and retinal ischemia occurred, with TMA evident on kidney biopsy. A TMA-like state also developed in guinea pigs IV administered PEO+. Acute tubular and glomerular renal injury was accompanied by nonheme iron deposition and hypoxia-inducible factor-1α upregulation in the renal cortex. Similar outcomes were observed following dosing with HMW PEO alone. IV exposure to the inert ingredients in reformulated extended-release oxymorphone can elicit TMA. Although prescription opioid abuse shows geographic variation, all physicians should be highly inquisitive of IV drug abuse when presented with cases of TMA.

Lacrimal intubation during dacryocystorhinostomy utilizing the STENTube

The traditional use of the Crawford tube for lacrimal intubation during dacryocystorhinostomy (DCR) carries several drawbacks. We describe the use of the STENTube for DCR intubation and detail its advantages. Retrospective, noncomparative, interventional case series; 313 patients with nasolacrimal duct obstruction (NLDO) underwent 339 DCRs (216 external, 123 endonasal) with the STENTube from January 2007 - June 2013 by 5 surgeons (RS, QN, TS, SB, TN) across 3 institutions (SUNY Downstate Medical Center, Texas Oculoplastics Consultants, and Moorfields Eye Hospital). Study outcome measures included patient demographics, surgical complications, and epiphora improvement/resolution. 206 (66%) females and 107 (34%) males had a mean age of 63 years (range 2-94 years). Distribution of diagnoses included: 314 complete idiopathic acquired NLDO, 20 partial idiopathic acquired NLDO, and 5 congenital complete NLDO. 316 (93%) were primary DCRs and 23 (7%) were revisions. Epiphora improved in 312 (92%) cases with 294 (86%) experiencing resolution with patent lacrimal irrigation at a mean last follow-up of 9.4 months. Twenty-eight (8%) patients experienced surgical complications with 16 (5%) experiencing tube prolapse, and 20 (6%) requiring re-operation. The STENTube represents a simple method for lacrimal intubation during external or endonasal DCR at a comparable cost to the Crawford tube. It allows for low prolapse rates without the need for additional endonasal fixation procedures, resulting in a simple and comfortable post-operative extraction without risk of lacrimal trauma. The STENTube is our preferred intubation technique during DCR, and should be considered by oculofacial surgeons performing DCR with intubation.

One aptamer, two functions: the full-length aptamer inhibits AMPA receptors, while the short one inhibits both AMPA and kainate receptors

AMPA and kainate receptors, along with NMDA receptors, are distinct subtypes of glutamate ion channels. Excessive activity of AMPA and kainate receptors has been implicated in neurological diseases, such as epilepsy and neuropathic pain. Antagonists that block their activities are therefore potential drug candidates. In a recent article in the Journal of Biological Chemistry by Jaremko et al. 2017, we have reported on the discovery and molecular characterization of an RNA aptamer of a dual functionality: the full-length RNA (101 nucleotide) inhibits AMPA receptors while the truncated or the short (55 nucleotide) RNA inhibits both the AMPA and kainate receptors. The full-length RNA aptamer was isolated through a specially designed, systematic evolution of ligands by exponential enrichment (SELEX) using only a single type of AMPA receptors expressed in HEK-293 cells. The design feature and the results of our recent article are highlighted here, as they demonstrate the utility of the SELEX approach and the potential of using a single AMPA receptor type to develop potent, novel RNA aptamers targeting multiple subunits and AMPA/kainate receptor subtypes with length-dependent functionalities.

Single synonymous mutation in factor IX alters protein properties and underlies haemophilia B

BACKGROUND

Haemophilia B is caused by genetic aberrations in the F9 gene. The majority of these are non-synonymous mutations that alter the primary structure of blood coagulation factor IX (FIX). However, a synonymous mutation c.459G>A (Val107Val) was clinically reported to result in mild haemophilia B (FIX coagulant activity 15%-20% of normal). The F9 mRNA of these patients showed no skipping or retention of introns and/or change in mRNA levels, suggesting that mRNA integrity does not contribute to the origin of the disease in affected individuals. The aim of this study is to elucidate the molecular mechanisms that can explain disease manifestations in patients with this synonymous mutation.

METHODS

We analyse the molecular mechanisms underlying the FIX deficiency through in silico analysis and reproducing the c.459G>A (Val107Val) mutation in stable cell lines. Conformation and non-conformation sensitive antibodies, limited trypsin digestion, activity assays for FIX, interaction with other proteins and post-translation modifications were used to evaluate the biophysical and biochemical consequences of the synonymous mutation.

RESULTS

The Val107Val synonymous mutation in F9 was found to significantly diminish FIX expression. Our results suggest that this mutation slows FIX translation and affects its conformation resulting in decreased extracellular protein level. The altered conformation did not change the specific activity of the mutated protein.

CONCLUSIONS

The pathogenic basis for one synonymous mutation (Val107Val) in the F9 gene associated with haemophilia B was determined. A mechanistic understanding of this synonymous variant yields potential for guiding and developing future therapeutic treatments.

Interactive iPhone/iPad App for Increased Tympanic Membrane Familiarity

INTRODUCTION

Otology relies on clinical examination to teach anatomy of the ear. The purpose of this report is to introduce the Buckingham Virtual Tympanum iPhone app as an adjuvant educational tool to teach the anatomical details of the tympanic membrane (TM).

MATERIALS AND METHODS

This app, available free at the Apple Store, was constructed using archival photographs of normal and abnormal TMs, stratified by difficulty. Each image has 4 labeled structures, linked to questions to encourage active learning. Third-year medical students then used the app to familiarize themselves with the TM.

RESULTS

The free app was readily accessible and functioned without technical issues. By being interactive, it forced the user into the role of active learner. This pilot study found that students who used the app understood images of the TM better than those who did not use it.

DISCUSSION

We introduce an interactive, iPhone-based smartphone application that we found to be a useful adjunct for teaching TM anatomy.

Abstract 5008: Elucidating HER2 molecular heterogeneity of circulating tumor cells among breast cancer patients

Background: HER2-positive tumors are often associated with poor prognosis, chemo-resistances and some patients eventually develop refractory disease during HER2 targeted therapy. While different mechanisms of trastuzumab resistance are being identified in recent years, contribution of confounding factors such as inherent genomic heterogeneity, equivocal HER2 amplifications and presence of chromosome 17 polysomy has been less understood thus far. In this pilot study, we aim to examine HER2 heterogeneity in CTCs obtained from breast cancer patients in the Asian population setting.

Methods: CTCs were enriched from blood samples using a label-free spiral microfluidics-based ClearCell® FX system. A total of 26 samples were collected from patients diagnosed with HER2 positive (17/26) and HER2 negative (9/26) breast cancer. The enriched CTCs were analyzed using conventional diagnostic modalities (fluorescence in-situ hybridisation (FISH) and immunocytochemistry) to examine HER2 status. Concordance rate between CTCs and matched primary tumor was evaluated.

Results: HER2-positive CTCs were successfully identified in 14 out of 17 HER2+ patients (82.4%); HER2 gene amplification and chromosome 17 polysomy were observed in 10(58.8%) and 13(76.5%) patients respectively. HER2+ CTC counts ranged from 2 to 30 cells from 7.5ml blood (median: 4 HER2+ CTCs/7.5ml). HER2 amplification was not observed in any of the 9 patients with HER2-negative tumors, though 5 out of 9 patients (55.6%) were identified with CTCs harbouring gain in chromosome 17 (median: 2 HER2+ CTCs/7.5ml). A “false positive” cut-off of more than 2 cells/7.5ml blood were established using receiver operating characteristic (ROC) curve analysis and a concordance rate of approximately 70% between paired tumor tissue and CTC among the 26 patients. Immunofluorescence labelling of CTCs with cytokeratin, CD45 and HER2 antibodies further revealed heterogeneity in HER2 expression on CTCs.

Conclusion: CTCs capture the heterogeneity of breast cancer, and could potentially overcome limitations of tissue biopsy which are site specific. HER2- patients, as confirmed by tissue biopsy, with HER2+ CTCs pose interesting questions while determining treatment regime.

Citation Format: Man Chun Leong, Tse Hui Lim, Chye Ling Tan, Yong Wei Chua, Elaine Hsuen Lim, Kiley Wei Jen Loh, Guek Eng Lee, Rebecca Dent, Raymond Chee Hui Ng, Andrew Wu, Wan-Teck Lim, Alvin Soon-Tiong Lim, Yoon-Sim Yap. Elucidating HER2 molecular heterogeneity of circulating tumor cells among breast cancer patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5008.

Abstract P6-04-03: Transcriptome profiling reveals enrichment of luminal feature in aged basal cell population in murine mammary gland

Aging is the number one risk factor for breast cancer development. Increasing evidence suggests the potential of mammary stem cells (MaSCs) and their progenitors to generate certain types of breast cancers through neoplastic transformation. Our previous study has shown increased percentage of MaSC-enriched basal cell population (Lin-CD49fhighCD24med) and increased MaSC frequency during aging in murine models. On the other hand, a recent study from another group showed an increased frequency of CD49fhigh cells in the human luminal population (CD227+) during aging, indicating possible aberrant expression of CD49f in the aged luminal cells. However, how these age-related luminal cells with basal markers are generated and how they contribute to potential breast cancer development remains unknown. Here we apply bioinformatics analysis on Next Generation Whole Transcriptome Sequencing data of MaSC-enriched basal cell population (Lin-CD49fhighCD24med) and luminal progenitor-enriched cell population (Lin-CD49flowCD24high) of both young (4 to 6 months) and old (26 to 31 months) mouse mammary gland to test the hypothesis that age-associated increase of basal cell population and MaSCs may be due to the gain of basal cell markers and features by luminal cells. By Gene Set Enrichment Analysis (GSEA) we found a significant loss of basal cell and basal mammosphere signatures and a significant enrichment of luminal cell and luminal mammosphere signature in the old basal cell population and mammospheres in comparison with the young basal cell population and mammospheres. The core enrichment luminal genes from GSEA are able to cluster the old MaSC-enriched basal cell population as well as mammospheres closer to the cluster of luminal population than to the young basal population. These analyses indicate that aging may be associated with an expansion of aberrant MaSCs with both basal and luminal markers in mice, which may be the precursors of certain types of breast cancer. We are now studying the potential function of the basal-like luminal cells in the aged basal population.

Citation Format: Gu X, Gao H, Wu A, Bandyopadhyay A, Dong Q, Sun L-Z. Transcriptome profiling reveals enrichment of luminal feature in aged basal cell population in murine mammary gland. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-04-03.

Investigation of the extraordinary null reconstruction phenomenon in polarization volume hologram

Polarization holography is the superposition of differently polarized beams. Due to its ability to record the polarization states, some extraordinary optical phenomena were found in the polarization holography. For example, the recently reported null-reconstruction phenomenon in polarization volume hologram is odd for the conventional holography which only records the amplitude and phase. In this paper, we perform a thorough investigation of the null reconstruction of polarization hologram recorded by orthogonal circularly polarized waves. To explore the mechanism behind this phenomenon, an interferometry was built to measure the phase difference between the same polarized components within the reconstructed wave. The phase difference of π was secured in our experiment, indicating a destructive interfering effect, which nicely explains the extraordinary null reconstruction observed in the polarization hologram.