Water-soluble PEG segmented mannose-based macromolecules: Synthesis, characterization and their biocompatibility.

The macromolecular architectures, namely mannose-based methacrylate acetyl-mannopyranoside and PEG block copolymers [AB type copolymer [PEG-b-PMAM], poly(ethyleneglycol)-b-poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside) and ABA type copolymer [PMAM-b-PEG-b-PMAM], poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside)-b-poly(ethyleneglycol)-b-poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside)] were synthesized by atom transfer radical polymerization (ATRP) method that were deacetylated to generate the corresponding water-soluble and biocompatible glycopolymer macromolecules. The molecular weight of acetyl and deacetylate macromolecules was in the range of 7083-9499 and 4659-6026, as determined by GPC and proton NMR spectra. The 5 % decomposition temperatures for acetylated methacrylate macromolecules (218-299 °C) were higher than the corresponding water-soluble macromolecules (204-248 °C). The conjugation of poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside) (PMAM) segment with the PEG block decreased the glass transition (Tg) value, and the water-soluble macromolecules displayed Tg in the range of 92-95 °C. The biocompatibility of the synthesized water-soluble mannose-based macromolecules was determined using Human Bone Derived Cells (HBDC) culture with the TCP (Tissue culture plastic) template as control. Using three different concentrations of the synthesized glycopolymers, HBDC's were cultured for 1, 3, and 7 days. The effect of mannomethacrylate macromolecules on mitochondrial activity of HBDC's was estimated using colorimetry that showed the conversion of MTS [3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide] to formazan (MTS assay). ABA type diblock copolymer architecture exhibited increased absorbance values of 3 and 7 day cultures at 1-100 M concentrations, with the highest values observed at a concentration of 1 M for day 3 cultures. The design of these novel mannose-based macromolecules is important for improving cell proliferation, cell adhesion, and osteointegration efficiency.

Ω76: A designed antimicrobial peptide to combat carbapenem- and tigecycline-resistant Acinetobacter baumannii.

Drug resistance is a public health concern that threatens to undermine decades of medical progress. ESKAPE pathogens cause most nosocomial infections, and are frequently resistant to carbapenem antibiotics, usually leaving tigecycline and colistin as the last treatment options. However, increasing tigecycline resistance and colistin's nephrotoxicity severely restrict use of these antibiotics. We have designed antimicrobial peptides using a maximum common subgraph approach. Our best peptide (Ω76) displayed high efficacy against carbapenem and tigecycline-resistant Acinetobacter baumannii in mice. Mice treated with repeated sublethal doses of Ω76 displayed no signs of chronic toxicity. Sublethal Ω76 doses co-administered alongside sublethal colistin doses displayed no additive toxicity. These results indicate that Ω76 can potentially supplement or replace colistin, especially where nephrotoxicity is a concern. To our knowledge, no other existing antibiotics occupy this clinical niche. Mechanistically, Ω76 adopts an α-helical structure in membranes, causing rapid membrane disruption, leakage, and bacterial death.

Metabolism of arachidonic acid in sheep uterus: in vitro studies.

Arachidonic acid (AA) metabolism in the non-pregnant sheep uterus was studied in vitro using conventional chromatographic and HPLC techniques. High expression of both lipoxygenase (LOX) as well as cyclooxygenase (COX) enzymes and their activities was found in the uterine tissues. On incubation of uterine enymes with AA, the LOX products formed were identified as 5-hydroperoxyeicosatetraenoic acid (5-HPETE), 12- and 15-hydroxyeicosatetraenoic acids (12- and 15-HETEs), based on their separation on TLC and HPLC. By employing differential salt precipitation techniques, the LOXs generating products 5-HPETE (5-LOX), 12-HETE and 15-HETE (12- and 15-dual LOX) were isolated. Based on their analysis on TLC, the COX products formed were identified as prostaglandins - PGF2alpha and prostacyclin derivative 6-keto PGF1alpha. The study forms the first report on the comprehensive analysis on the metabolism of AA in sheep uterus in vitro via the LOX and COX pathways.