In this study, amphiphilic polyoxanorbornene with different alkyl and aromatic phosphonium side chains was synthesized and investigated their biocidal properties.

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Antimicrobial peptides are widely preferred drugs for infectious disease treatment. Inspired from natural antimicrobial peptides, short peptides showing good antibacterial activity are designed in this study. The peptides consisted of repeating hydrophobic and positively charged amino acids, positioned on one side of the alpha helix. Arginine in peptides resulted in better activity compared to lysine. Having positively charged amino acids at both ends, created better activity for Escherichia coli compared to Staphylococcus aureus, and only at one end, created comparable activities for both organisms. Positioning of arginines on one side in zigzag form prominently increased the activity compared to positioning on linear axis. Elongating hydrophobic tail resulted in self-binding and eliminated the antibacterial activity. Molecular dynamic simulations suggested that a single molecule is capable of creating hydrophilic channel in membrane. Electron microscopic examination of staphylococci treated with these peptides revealed that the bacteria split into halves. Docking studies revealed that the peptides strongly bind to the major peptidoglycan synthesizing membrane protein, glycosyltransferase. The unique composition and design of these peptides revealed a promising antibacterial activity that may further lead to the development of new antimicrobial compounds effective to multi-drug resistant organisms.

Objective: Dientamoeba fragilis is an intestinal protozoan found in colonic lumen and it has been demonstrated that it can lead to various gastrointestinal and dermatological complaints. It has been discussed lately that D. fragilis can be found also in high prevalence among healthy individuals and could be a member of healthy gut microbiota. The aim of this study was to compare the prevalence of D. fragilis between patient and healthy-control groups from Istanbul, and to study clinical outcomes of the infection it causes on the patient group ,and patient characteristics. Method: Stool samples of 184 patients admitted to Acıbadem Health Group hospitals in Istanbul between 2016-2018, and 156 healthy controls were examined in the study. After microbiological and parasitological assessments of stool samples, DNA isolation was made followed by conventional PCR test using specific primers. Results: D. fragilis was detected in 15 of 184 (8.2%) patients and 42 of 156 (26.9%) controls, and the intergroup difference was significant (p<0.05). In the study group Salmonella spp. was detected in 3, and Rotavirus in 1 of the D. fragilis positive individuals. Six out of 15 D. fragilis positive individuals in the study group were women and their average age (n=24.3) was higher than other groups (p=0.25). Fifty-five of 57 (96.5%) D. fragilis positive individuals were in the pediatric age group. The leading complaints were diarrhea, anorexia and abdominal pain, while 3 of the 15 patients reported itching and urticaria. Conclusion: These preliminary results related to the metropolitan city of Istanbul tend to support the fact that D. fragilis may show pathogenic effects in some cases but it is more common among healthy individuals. Considering the similar results from different regions of the world, further studies are essential to unveil under which conditions D. fragilis is silent (friend) and acts as a pathogen (foe).