Antibiotics with new mechanisms of action are urgently required to combat the growing health threat posed by resistant pathogenic microorganisms. We synthesized a family of peptidomimetic antibiotics, based on the antimicrobial peptide protegrin I. Several rounds of optimization gave a lead compound that was active in the nanomolar range against gram-negative Pseudomonas sp., but was largely inactive against other Gram-negative and Gram-positive bacteria. Biochemical and genetic studies showed the peptidomimetics had a non-membrane-lytic mechanism of action and identified a homologue of the ß-barrel protein LptD (Imp/OstA), which functions in outer membrane biogenesis, as a cellular target. The peptidomimetic showed potent antimicrobial activity in a mouse septicemia infection model. Drug-resistant strains of Pseudomonas are a serious health problem, so this family of antibiotics may have important therapeutic applications. A synthesized antibiotic targets a protein involved in outer membrane biogenesis to selectively kill Pseudomonas pathogens. 1 Peptidomimetic Antibiotics Target Outer Membrane Biogenesis in Pseudomonas aeruginosa AbstractAntibiotics with new mechanisms of action are urgently required to combat the growing health

The function of the liver is well-preserved during the aging process, although some evidence suggests that liver regeneration might be impaired with advanced age. We observed a decreased ability of the liver to restore normal volume after partial hepatectomy in elderly mice, and we identified a pathway that rescued regeneration and was triggered by serotonin. 2,5-dimethoxy-4-iodoamphetamine (DOI), a serotonin receptor agonist, reversed the age-related pseudocapillarization of old liver and improved hepatosinusoidal blood flow. After hepatectomy, the open fenestrae were associated with a restored attachment of platelets to endothelium and the initiation of a normal regenerative response, including the up-regulation of essential growth mediators and serotonin receptors. In turn, hepatocyte proliferation recovered along with regain of liver volume and animal survival. DOI operates through the release of VEGF, and its effects could be blocked with anti-VEGF antibodies both in vitro and in vivo. These results suggest that pseudocapillarization in the aged acts as a barrier to liver regeneration. DOI breaks this restraint through an endothelium-dependent mechanism driven by VEGF. This pathway highlights a target for reversing the age-associated decline in the capacity of the liver to regenerate.aging liver | fenestrations | sinusoidal microperfusion T he most significant limiting factor for survival after liver surgery and transplantation of a partial graft is the ability of the remnant liver to regenerate (1-3), as documented in human (4, 5) and several animal models (6-8). Although in young patients, small remnant livers (up to 25% of the normal size) can regenerate fully within a few weeks, this process is impaired in the diseased (9, 10) and possibly, older (11) livers.Conventional histological examination of the liver hardly differs between young and old individuals, although a few features have been identified. For example, the size of the liver and the sinusoidal flow decrease with age, akin to the energy stores (glycogen and ATP in hepatocytes) (12-16). It is well-known that there is an age-associated decline in the clearance of a number of drugs (17-19). We have recently shown that protective strategies during liver surgery, such as ischemic preconditioning, are lost in patients older than 65 y of age (14,20,21).Impaired hepatocyte proliferation was also documented in old mice after major hepatectomy, but the impact on animal survival and underlying mechanisms was not evaluated (22). Finally, a study from Japan in recipients of partial grafts showed a lower liver volume 1 wk after transplantation in patients receiving a graft from donors older than 50 y of age (23). Advanced age is also associated with ultrastructural changes in the hepatic sinusoid, called pseudocapillarization, which includes the defenestration (reduction of porosity) and thickening of the sinusoidal endothelium (24-26). Similar findings for the defenestration and capillarization of the hepatic sinusoidal endothelium have been observed in t...

As functionalized chitosans hold great potential for the development of effective and broad-spectrum antibiotics, representative chitosan derivatives were tested for antimicrobial activity in neutral media: trimethyl chitosan (TMC), carboxy-methyl chitosan (CMC), and chitosan-thioglycolic acid (TGA; medium molecular weight: MMW-TGA; low molecular weight: LMW-TGA). Colony forming assays indicated that LMW-TGA displayed superior antimicrobial activity over the other derivatives tested: a 30 min incubation killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced colony counts by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi). To elucidate LMW-TGA effects at the cellular level, microscopic studies were performed. Use of fluorescein isothiocyanate (FITC)-labeled chitosan derivates in confocal microscopy showed that LMW-TGA attaches to microbial cell walls, while transmission electron microscopy indicated that this derivative severely affects cell wall integrity and intracellular ultrastructure in all species tested. We therefore propose LMW-TGA as a promising and effective broad-band antimicrobial compound.

BackgroundPhotosensitizers are used in photodynamic therapy (PDT) to destruct tumor cells, however, their limited solubility and specificity hampers routine use, which may be overcome by encapsulation. Several promising novel nanoparticulate drug carriers including liposomes, polymeric nanoparticles, metallic nanoparticles and lipid nanocomposites have been developed. However, many of them contain components that would not meet safety standards of regulatory bodies and due to difficulties of the manufacturing processes, reproducibility and scale up procedures these drugs may eventually not reach the clinics. Recently, we have designed a novel lipid nanostructured carrier, namely Lipidots, consisting of nontoxic and FDA approved ingredients as promising vehicle for the approved photosensitizer m-tetrahydroxyphenylchlorin (mTHPC).ResultsIn this study we tested Lipidots of two different sizes (50 and 120 nm) and assessed their photodynamic potential in 3-dimensional multicellular cancer spheroids. Microscopically, the intracellular accumulation kinetics of mTHPC were retarded after encapsulation. However, after activation mTHPC entrapped into 50 nm particles destroyed cancer spheroids as efficiently as the free drug. Cell death and gene expression studies provide evidence that encapsulation may lead to different cell killing modes in PDT.ConclusionsSince ATP viability assays showed that the carriers were nontoxic and that encapsulation reduced dark toxicity of mTHPC we conclude that our 50 nm photosensitizer carriers may be beneficial for clinical PDT applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0221-x) contains supplementary material, which is available to authorized users.

The use of lipid-based nanoparticles for the delivery of biomacromolecules has attracted considerable attention due to the current interest in protein-based therapeutics. Cubosomes protect the incorporated therapeutics, which are susceptible to degradation by enzymes, thereby improving their bioavailability, and concomitantly enhance cellular uptake. The cubosome nanoparticles presented herein were loaded with bovine serum albumin (BSA) and characterized by small-angle X-ray scattering and dynamic light scattering techniques, while the BSA encapsulation and its release were evaluated in vitro. The ability of this formulation to increase the cellular uptake of albumin by 2-fold was tested on various types of renal tubular cells and confirmed by in vivo renal uptake experiments in mice. The obtained results show that cubosomes are able to deliver BSA inside the cell through distinct uptake and intracellular routing. These data were substantiated, with evidence of a high cubosome-mediated uptake of BSA in Clcn5 knockout mice characterized by defective receptor-mediated endocytosis. The use of cubosomes as a delivery system thus represents a promising approach to overcome the low endocytic uptake in diseased epithelial cells and to treat dysfunctions of the kidney proximal tubule.