Ultrasensitive Detection of Lipid-Induced Misfolding of the Prion Protein at the Aqueous-Liquid Crystal Interface.

The misfolding of the α-helical cellular prion protein into a self-propagating ß-rich aggregated form is a key pathogenic event in fatal and transmissible neurodegenerative diseases collectively known as prion diseases. Herein, we utilize the interfacial properties of liquid crystals (LCs) to monitor the lipid-membrane-induced conformational switching of prion protein (PrP) into ß-rich amyloid fibrils. The lipid-induced conformational switching resulting in aggregation occurs at the nanomolar protein concentration and is primarily mediated by electrostatic interactions between PrP and lipid headgroups. Our LC-based methodology offers a potent and sensitive tool to detect and delineate molecular mechanisms of PrP misfolding mediated by lipid-protein interactions at the aqueous interface under physiological conditions.

Elucidating liquid crystal-aqueous interface for the study of cholesterol-mediated action of a ß-barrel pore forming toxin.

Pore-forming toxins (PFTs) produced by pathogenic bacteria serve as prominent virulence factors with potent cell-killing activity. Most of the ß-barrel PFTs form transmembrane oligomeric pores in the membrane lipid bilayer in the presence of cholesterol. The pore-formation mechanisms of the PFTs highlight well-orchestrated regulated events in the membrane environment, which involve dramatic changes in the protein structure and organization. Also, concerted crosstalk between protein and membrane lipid components appears to play crucial roles in the process. Membrane-damaging lesions formed by the pore assembly of the PFTs would also be expected to impose drastic alterations in the membrane organization, details of which remain obscure in most of the cases. Prior reports have established that aqueous interfaces of liquid crystals (LCs) offer promise as responsive interfaces for biomolecular events (at physiologically relevant concentrations), which can be visualized as optical signals. Inspired by this, herein, we sought to understand the lipid membrane interactions of a ß-barrel PFT i.e., Vibrio cholerae cytolysin (VCC), using LC-aqueous interfaces. Our results show the formation of dendritic patterns upon the addition of VCC to the lipid embedded with cholesterol over the LC film. In contrast, we did not observe any LC reorientation upon the addition of VCC to the lipid-laden LC-aqueous interface in the absence of cholesterol. An array of techniques such as polarizing optical microscopy (POM), atomic force microscopy (AFM), and fluorescence measurements were utilized to decipher the LC response to the lipid interactions of VCC occurring at these interfaces. Altogether, the results obtained from our study provide a novel platform to explore the mechanistic aspects of the protein-membrane interactions, in the process of membrane pore-formation by the membrane-damaging PFTs.

Could Extension Into the Lacrimal Gland and Sac Thwart Topical Chemotherapy for Intraepithelial Sebaceous Carcinoma?

PURPOSE: To identify the frequency of intraepithelial (Pagetoid) spread beyond the ocular surface-namely beyond conjunctiva and cornea-in patients undergoing orbital exenteration for advanced periocular Sebaceous carcinoma (SC). DESIGN: A retrospective, noncomparative observational case series. SUBJECTS: Patients undergoing orbital exenteration for biopsy-proven SC, at Moorfields Eye Hospital between 1997 and 2013. METHODS: Review of clinical records and histological specimens, with particularly reference to involvement of conjunctiva and the extent of Pagetoid infiltration beyond the examinable ocular surface-here termed "hidden" disease. MAIN OUTCOME MEASURES: Histological evidence of intraepithelial SC within the lacrimal sac or lacrimal gland. RESULTS: Twenty-nine patients had clinical data and histological specimens adequate for review. Seventeen (59%) did not have a discrete mass (clinically or histologically) and, on clinical examination, were thought to only have extensive intraepithelial carcinoma; foci of microscopic invasion were, however, detected histologically in 11/17 (65%) of these specimens. Moreover, the in situ carcinoma was found to have invaded far in lacrimal gland ductules in 1/17 patients, in the lacrimal sac (in 2 patients; 12%) or in both the gland and sac (in 2 patients); these 5/17 (29%) cases all showed extensive poorly differentiated intraepithelial SC. Of the 12 other patients who had both Pagetoid spread and a clinically evident nodule, 3 had histological evidence of "hidden" disease. CONCLUSION: Although-due to their being operated in the era prior to the accepted usage of topical therapy for this condition-some of these exenterations might have had particularly advanced in situ SC, over a quarter of patients with periocular SC warranting orbital exenteration show "hidden" intraepithelial tumor within the lacrimal gland and sac. This important finding might significantly reduce the efficacy (particularly in the lacrimal gland) of the various topical therapies used for in situ SC of the ocular surface, and it also emphasizes the importance of excising both the lacrimal gland and sac in all orbital exenterations for this particular tumor.

Extension of Masses Involving the Lacrimal Sac to Above the Medial Canthal Tendon.

PURPOSE: Retention mucoceles of the lacrimal sac almost always expand below the medial canthal tendon (MCT), whereas the very much rarer malignancies involving the lacrimal sac may progress to form a mass above the tendon. In this study, the incidence of malignancy was determined for patients with a preoperative decision to undergo biopsy for a clinically suspect, hard lacrimal sac mass, together with the proportion having a tumor extending above the MCT. METHODS: Patients thought-on the basis of having a firm, immobile mass centered on the lacrimal sac fossa-to possibly have lacrimal sac malignancy were identified from a database of biopsies between 1989 and 2020. A retrospective review of their clinical, radiologic, and pathologic records was undertaken. RESULTS: Fifty-three patients (24 male; 45%) underwent biopsy of atypical masses of the lacrimal sac, of which 47 of 53 (89%) extended above the MCT. Seventy-seven percent (41/53) patients had malignancy-26 primary carcinomas and 15 secondary tumors (14 lymphomas or hematopoietic and 1 neuroendocrine)-and 12 had benign conditions (6 transitional cell papillomatosis, 5 chronic inflammation, and 1 solitary fibrous tumor); all the benign pathologies extended above the MCT. The age at presentation and duration of symptoms was similar in patients with benign or malignant pathology. One-fifth of malignant lesions had pain, whereas all the benign conditions were painless, and acute dacryocystitis was relatively uncommon-occurring in only 13% of patients. CONCLUSIONS: If a firm and immobile lacrimal sac mass extends above the MCT, it has about a 74% chance of being malignant and, if pain is present, the lesion is more likely to be so. Clinically suspicious masses in the lacrimal sac fossa, whether benign or malignant, appear to present at the same age and with a similar duration of symptoms.

Impact of chemotherapy on symptom profile, oxidant-antioxidant balance and nutritional status in non-small cell Lung Cancer.

BACKGROUND: Lung cancer is associated with an oxidant-antioxidant imbalance that is implicated in tumor progression. However, the association of this imbalance on disease burden and treatment response is unclear. The effect of chemotherapy on oxidative stress, antioxidant status, and nutritional profile in patients with advanced nonsmall cell lung cancer (NSCLC) was prospectively evaluated. SUBJECTS AND METHODS: Patients with confirmed cytological/histological diagnosis of NSCLC were recruited. Performance status was determined using the Eastern Cooperative Oncology Group grading and the Karnofsky Performance Scale. Skin fold anthropometry was done for nutritional assessment. All patients received chemotherapy with intravenous carboplatin and paclitaxel at three-weekly intervals. Response was assessed after four cycles by repeat imaging. Plasma levels of total antioxidant status (TAS), malondialdehyde (MDA), and glutathione peroxidase (GPx) levels were estimated using commercially available kits, and the change was correlated with clinical outcome, response to chemotherapy, performance status, and nutritional profile. RESULTS: Thirty-five cases were studied (92% males), with a mean (SD) age of 56.2 (9.3) years. Following treatment, majority of patients demonstrated stable disease (n = 15 [42%]), followed by partial response (29%), progressive disease (22%), and complete remission (6%). Significant improvement occurred in respiratory symptoms. Body fat declined while subscapular skinfold thickness and 6-min walk distance increased. Spirometric values and performance status remained unchanged. GPx levels declined significantly while no notable change was observed in MDA and TAS levels. CONCLUSIONS: Chemotherapy for NSCLC improves symptoms, nutritional status, and exercise capacity but worsens the antioxidant status.

Quantification of Rac1 and Rac1b in serum of non small cell lung cancer by label free real time assay.

BACKGROUND: Rac proteins play a major role in tumorogenesis. We quantified Rac1 and Rac1b in serum of non small cell lung cancer (NSCLC) patients. METHODS: The blood of 77 NSCLC patients and 52 healthy controls were collected and quantified the concentration of Rac1 and Rac1b mainly by surface plasmon resonance and it was verify by Western blot analysis. RESULTS: Rac1 and Rac1b were found to be significantly over expressed in serum of NSCLC patients compare to healthy controls. The level of Rac proteins were found to be increased in all stages of cancer. Despite the low survival rate, we managed to collect serum sample of the 18 follow up patients after the therapy, where 11 patients' of CR+PR group showed down regulation of the Rac protein after chemotherapy and unfortunately 80% patients died during the study period. CONCLUSION: The high specificity and sensitivity obtained from ROC analysis for Rac1 and Rac1b envisaged it to be used as a serum diagnostic marker in the early stage of cancer.