The Influence of Cellulose-Type Formulants on Anti-Candida Activity of the Tyrocidines.

Candida species are highly adaptable to environmental changes with their phenotypic flexibility allowing for the evasion of most host defence mechanisms. Moreover, increasing resistance of human pathogenic Candida strains has been reported against all four classes of available antifungal drugs, which highlights the need for combinational therapies. Tyrocidines are cyclic antimicrobial peptides that have shown synergistic activity with antifungal drugs such as caspofungin and amphotericin B. However, these cyclodecapeptides have haemolytic activity and cytotoxicity, but they have been used for decades in the clinic for topical applications. The tyrocidines tend to form higher-order structures in aqueous solutions and excessive aggregation can result in variable or diminished activity. Previous studies have shown that the tyrocidines prefer ordered association to celluloses. Therefore, a formulation with soluble cellulose was used to control the oligomer stability and size, thereby increasing the activity against Candida spp. Of the formulants tested, it was found that commercial hydroxy-propyl-methyl cellulose, E10M, yielded the best results with increased stability, increased anti-Candida activity, and improved selectivity. This formulation holds promise in topical applications against Candida spp. infections.

Oligomerisation of tryptocidine C, a Trp-rich cyclodecapeptide from the antimicrobial tyrothricin complex.

Tryptocidine C (TpcC, cyclo[D-Phe1-Pro2-Trp3-D-Trp4-Asn5-Gln6-Trp7-Val8-Orn9-Leu10]) is a broad-spectrum antimicrobial peptide in the tyrothricin complex produced by a soil bacterium, Brevibacillus parabrevis. Electrospray mass spectrometric studies reveal the oligomerisation of TpcC into dimers and higher oligomers, analogous to tyrocidine C (TrcC, Trp7 replaced by Tyr7). Ion mobility mass spectrometry (IMMS) further confirms the formation of stable peptide dimers and tetramers with diameters of 2.7 nm and 3.3 nm, respectively, calculated from collisional cross section (CCS). Molecular dynamic simulations and docking studies support the formation of amphipathic dimers, with a diameter of 2.5 ± 0.07 nm calculated from low energy model CCS. Circular dichroism and IMMS studies point towards dynamic hydrogen-bonded conformational changes up to 28-33 µM after which the structures become more static (or in equilibrium). Fluorescence studies indicate aromatic stacking of Trp residues with a CMC of 18 µM in aqueous solutions. The concentration and time dependent interaction of Trp in oligomers indicate cooperativity in the TpcC oligomerisation that leads to the formation of higher order microscopic structures. Scanning electron microscopy studies unequivocally shows that TpcC forms nanospheres with a mean diameter of 25 nm. Repeated smaller oligomeric units, possibly dimers and tetramers, self-assemble to form these nanospheres.

Down-regulated MicroRNA 148b expression as predictive biomarker and its prognostic significance associated with clinicopathological features in non-small-cell lung cancer patients.

BACKGROUND: Lung cancer is most common and is the leading cause of cancer-related death in both men and women worldwide. Understanding of the molecular mechanisms underlying non-small cell lung cancer (NSCLC) development and progression are important. In the present study, we investigated the potential role of miR-148b expression analysis as potential lung cancer biomarker with the correlation of circulating miR-148b to clinicopathological features. METHODS: A total of 104 NSCLC patients were diagnosed and cancer tissues together with adjacent normal tissues were evaluated. Quantitative Real-time PCR method was utilized to evaluate the expression levels of miR-148b. In addition, we investigated to clarify the relationship of miR-148b with clinicopathological features and survival in patients with NSCLC. RESULTS: Our findings showed that miR-148b was downregulated in tumor tissues when compared with corresponding adjacent normal lung tissues (0.34 ± 0.13 vs. 1.00 ± 0.57, P < 0.05). Moreover decreased expression of miR-148b was significantly related to TNM stage (P = 0.001) and lymph node-metastasis (P = 0.023). This findings suggested that miR-148b was down-regulated in NSCLC patients and may play a key role as a tumor suppressor gene in NSCLC. Kaplan-Meier survival analysis and log-rank test suggested that low-expression group of patients had significantly shorter overall survival than high-expression group (log-rank test: P = 0.031). Multivariate Cox proportional hazards model analysis indicated that low miR-148b expression was independently linked to poor survival of patients with NSCLC (HR = 3.215, 95 % CI: 1.543-10.621, P = 0.021) and other factors were not significant independent predictor of survival in patients with NSCLC. CONCLUSION: Our findings demonstrated that miR-148b may play a role as independent prognostic factor for patients with NSCLC.