Mucoepidermoid carcinoma of the conjunctiva with lung metastasis.

A 36‑year‑old lady presented with redness and decreased vision in right eye since 6 months. She was earlier diagnosed of cavitary lung lesion, presumed secondary to tuberculosis and treated with anti‑tubercular treatment for 4 months. Examination of affected right eye revealed nil light perception, conjunctival congestion with an exuberant mass in the inferotemporal bulbar conjunctiva, proptosis, iris neovascularization, 360° closed angles, intraocular pressure of 48 mm Hg, exudative retinal detachment, uveal mass and orbital extension. A diagnostic needle biopsy of uveal mass revealed malignant cells. Computed tomography‑guided lung biopsy revealed squamous cell carcinoma (SCC), indicating metastatic spread from the orbit. She underwent lid‑sparing exenteration of the right eye. Histopathological examination of the orbital tissue revealed mucoepidermoid carcinoma arising from the conjunctiva with extensive invasion into the orbital tissue, muscle fibers, sclera, choroid and optic nerve. Multiple tumor emboli were seen in the lumen of orbital blood vessels. In conclusion, mucoepidermoid carcinoma of the conjunctiva is a rare, aggressive variant of SCC. Early intervention is essential to prevent intraocular invasion and systemic metastasis.

Comparative Modeling and Molecular Dynamics Simulation of Substrate Binding in Human Fatty Acid Synthase: Enoyl Reductase and beta-Ketoacyl Reductase Catalytic Domains

Fatty acid synthase (FASN, EC 2.3.1.85), is a multi-enzyme dimer complex that plays a critical role in lipogenesis. This lipogenic enzyme has gained importance beyond its physiological role due to its implications in several clinical conditions-cancers, obesity, and diabetes. This has made FASN an attractive pharmacological target. Here, we have attempted to predict the theoretical models for the human enoyl reductase (ER) and beta-ketoacyl reductase (KR) domains based on the porcine FASN crystal structure, which was the structurally closest template available at the time of this study. Comparative modeling methods were used for studying the structure-function relationships. Different validation studies revealed the predicted structures to be highly plausible. The respective substrates of ER and KR domains-namely, trans-butenoyl and beta-ketobutyryl-were computationally docked into active sites using Glide in order to understand the probable binding mode. The molecular dynamics simulations of the apo and holo states of ER and KR showed stable backbone root mean square deviation trajectories with minimal deviation. Ramachandran plot analysis showed 96.0% of residues in the most favorable region for ER and 90.3% for the KR domain, respectively. Thus, the predicted models yielded significant insights into the substrate binding modes of the ER and KR catalytic domains and will aid in identifying novel chemical inhibitors of human FASN that target these domains.

Culture & characterisation of limbal epithelial cells & oral mucosal cells.

Background & objectives: Sources of autologous tissue that can functionally replace the corneal epithelium have been considered as an alternative to allogenous limbal transplants for limbal stem cells deficiency (LSCD). The aim of the present study was to compare the characterization of oral mucosa with limbal epithelial cells by markers using reverse transcriptase polymerase chain reaction (RT-PCR). Methods: Experiments were performed using oral tissue (n=6) obtained from patients who underwent oral mucosal graft for LSCD. Confluent cultures of limbus and oral mucosa epithelial cells were characterized by the pututative stem cell markers using RT-PCR. The morphological characteristics of cultivated epithelial cells were analyzed by haematoxylin and eosin staining and phase contrast microscopy. Results: Confluent sheets of epithelial cells were seen at the end of 14th day resembling the morphological features of limbal epithelia. RT–PCR analysis showed that cultured oral epithelial cells expressed markers such as ABCG2, p63, delta Np63, isoforms of p63, Keratin 3 (K3), membrane protein – Mucin (MUC 1, 4 and 16) and Antimicrobial Peptide - AMP (Human β Defensin – hBD 1, 2 and 3). Interpretation & conclusions: Oral epithelial cultures have morphological features resembling corneal and limbal epithelial cells by expressing similar marker genes. Thus, feasibility of clinical use of oral epithelial cells need be evaluated for allogenous limbal transplants.

Signal transduction pathway involved in the ex vivo expansion of limbal epithelial cells cultured on various substrates.

Background & objectives: Ex vivo expansion of the limbal epithelial cells activates the nerve growth factor (NGF) mediated downstream signal transduction pathway. It is not clear as to which factors control the stemness of the corneal limbal stem cells, i.e., the maintenance of stem cell properties. It is likely that various signaling pathways are involved, including Notch, Wnt and NGF signaling, etc. In the present study, we investigated the activation of phosphoinositide-3-kinase (PI3K) pathway on cells cultured over the chitosan matrix, chitosan silver matrix, chitosan gold matrix, intact and denuded human amniotic membrane (HAM). Methods: Human limbal biopsies obtained from the cadaveric donor eyes were used in this study. The cells cultured over different substrate and observed for the activation of the downstream signaling molecules of PI3K/Akt/FKHRL1 pathway. Western blotting was done to prove the results. Results: The cells cultured over the intact HAM showed the activation of the downstream signaling molecules of PI3K/Akt/JNK pathway compared to the cells grown over other substrates. On inhibition of the PI3K activity there was absence of phosphorylation of downstream effectors in the limbal epithelial cells from the explant culture over the intact HAM. Interpretation & conclusions: The ex vivo expansion of human limbal epithelial progenitor cells on intact HAM was mediated by PI3K/Akt/FKHRL1 pathway, which is known to govern cell survival, and the mitogen-activated protein kinase (MAPK) pathway, known to control the cell mitosis.