The effect of chitosan and PEG polymers on stabilization of GF-17 structure: A molecular dynamics study.

We examine the interactions of chitosan and polyethylene glycol (PEG) with antimicrobial peptide GF-17 to identify a suitable carrier to improve the peptide drug delivery systems. To this end, the molecular dynamics simulations are used to determine the interactions of a typical antimicrobial peptide GF-17 with the chitosan and PEG polymers. The findings indicate the great potential of the peptide to maintain its secondary structure in the adjacent to chitosan polymers. During the interaction with chitosan polymers, the structure of the peptide has smaller fluctuations compared to the PEG polymers. Also, in the presence of both the polymers, the PEG polymers are situated closer to the peptide than chitosan polymers. Moreover, the analysis indicates that the acidic residues and phenylalanine play a crucial role in peptide-polymer interactions. This research provides a valuable insight into the design of polymer surfaces for drug delivery applications such as controlled-release peptide delivery systems.

Clinical and histological indicators of proximal and distal gastric cancer in eight provinces of Iran.

BACKGROUND AND AIM: Gastric cancer is the second most common cancer worldwide. In this study the clinical and histological features of gastric cancer in the cardia and distal stomach were evaluated. METHOD: Proximal and distal gastric cancer diagnosed and treated in eight provinces of Iran from 2010-2011 were reviewed in all collected cases. The age standardized incident rates were calculated and tumor location and histological type were recorded. RESULTS: The age-standardized incidence rate for the eight centers was 40.6 per 100,000 populations per year with an upper and lower range of 22.1 and 102.4 per 100,000 population per year. Thirty four percent of the tumors were located in the cardia, 3% in fundus, and 63% in the distal stomach. In 7 provinces the prevalence of distal tumors was significantly greater than proximal tumors (p=0.006). A significant relationship was observed between diffuse form of gastric cancer and distal gastric tumors (p=0.007) and between poor tumor differentiation and distal gastric tumors (p<0.001). CONCLUSIONS: the result of this study shows that distal gastric cancer is more common than proximal gastric cancer in Iran.