http://precedings.nature.com/tags/antimicrobial%20peptides Recently posted documents tagged with 'antimicrobial peptides' Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/3068/version/2 WithdrawnIncomplete data http://precedings.nature.com/documents/3068/version/2 Mon, 04 May 2009 02:08:49 UTC Design of selective peptide antibiotics by using the sequence moment concept hdl:10101/npre.2009.3068.2 2009-05-04 Davor Juretic Nature Precedings 2009-05-04T02:08:49Z Manuscript Biotechnology Pharmacology Bioinformatics http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/3068/version/1 New antibiotics against multidrug-resistant bacteria are urgently needed, but rapid acquisition of resistance limits their usefulness. Endogenous antimicrobial peptides (AMPs) with moderate selectivity, but multimodal mechanism of action, have remained effective against bacteria for millions of years. Their therapeutic application, however, requires optimizing the balance between antibacterial activity and selectivity, so that rational design methods for increasing selectivity are highly desirable. We have created training (n=36) and testing (n=37) sets from frog-derived AMPs with determined therapeutic index (TI). The 'sequence moments' concept then enabled us to find a one-parameter linear model resulting in a good correlation between measured and predicted TI (r<sup>2</sup>=0.83 and 0.64 for each set, respectively). The concept was then used in the AMP-Designer algorithm to propose primary structures for highly selective AMPs against Gram-negative bacteria. Testing the activity of one such peptide produced a TI>200 as compared to the best AMP in the data-base, with TI=125. http://precedings.nature.com/documents/3068/version/1 Fri, 17 Apr 2009 20:54:43 UTC Design of selective peptide antibiotics by using the sequence moment concept hdl:10101/npre.2009.3068.1 2009-04-17 Davor Juretic Nature Precedings 2009-04-17T20:54:43Z Manuscript Biotechnology Pharmacology Bioinformatics http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/2006/version/1 Thanatin and s-thanatin were insect antimicrobial peptides which have shown potent antimicrobial activities on a variety of microbes. In order to investigate the effect of cations and pH on the activity of these peptides against Gram-negative bacteria and Gram-positive bacteria, the antimicrobial activities of both peptides were studied in increasing concentrations of monovalent cations (K+ and Na+), divalent cations (Ca2+ and Mg2+) and H+. The NCCLS broth microdilution method showed that both peptides were sensitive to the presence of cations. The divalent cations showed more antagonized effect on the activity against Gram-negative bacteria than the monovalent cations, since the two peptides lost the ability to inhibit bacterial growth at a very low concentration. In addition, the activities of both peptides tested were not significantly affected by pH. Comparing to studies of other antibacterial peptide activities, our data support a hypothesis that positive ions affect the sensitivity to cation peptides. http://precedings.nature.com/documents/2006/version/1 Wed, 25 Jun 2008 09:40:41 UTC Effects of Cations and PH on Antimicrobial Activity of Thanatin and s-Thanatin against Escherichia coli ATCC25922 and B. subtilis ATCC 21332 hdl:10101/npre.2008.2006.1 2008-06-25 Linxian Li Nature Precedings 2008-06-25T09:40:41Z Manuscript Microbiology Pharmacology http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/1967/version/1 Medical devices are an integral part of therapeutic management; despite their importance, they carry a significant risk of microbial infection. Bacterial attachment to a medical device is established by a single, multiplying organism, leading to subsequent biofilm formation. To date, no preventative measures have impacted the incidence of device-related infection. We report the bidirectional covalent coupling of an engineered cationic antimicrobial peptide (eCAP), WLBU2, to various biological surfaces is accomplished. These surfaces included (i) a carbohydrate-based gel matrix, (ii) a complex polymeric plastic bead, and (iii) a silica-calcium phosphate nanocomposite associated with bone reconstruction. WLBU2-conjugated surfaces are shown to retain potent antimicrobial activity related to bacterial surface adhesion. This study provides proof of principle that covalently coating laboratory and bone-regenerating materials with eCAPs has the potential for decreasing infection rates of implanted devices. These findings have important consequences to the patient management component of our current health care technology. http://precedings.nature.com/documents/1967/version/1 Wed, 11 Jun 2008 17:34:37 UTC Peptides as potent antimicrobials tethered to a solid surface: Implications for medical devices hdl:10101/npre.2008.1967.1 2008-06-11 Timothy A. Mietzner Nature Precedings 2008-06-11T17:34:37Z Manuscript Biotechnology Microbiology http://creativecommons.org/licenses/by/3.0/ http://precedings.nature.com/documents/930/version/1 Trichophyton rubrum is the main agent causing dermatophytosis (1). Keratinocytes areconsidered to be the first physical barrier of defense against pathogens (2). But notonly a physical barrier. They recognize antigens through Toll like receptors (TLR) (3).The activation of this TLR, present on the surface of the keratinocytes, induce theexpression of different pro-inflammatory cytokines, co-stimulatory molecules andantimicrobial peptides such as β-defensins (4).The main objective of this work is to determine if lipopolysaccharides of G – bacteria(LPS), lipotheichoic acid from G+ bacteria (LTA), and conidias, isolated from T. rubrumwere able to activate the expression of TLR2 and TLR6 on the cell surface of a primaryculture of human keratinocytes through Flow cytometry. Furthermore we are looking forthe presence of β-defensins 1 and 2, IL-1b and IL-8 in the supernatant, of the abovementioned culture of cells, by Western blot.From the flow cytometry data, the preliminary results showed an important dispersionin terms of proliferation, increase in size and granularity of keratinocytes, from primarycultures of skin from healthy donors, stimulated 6 hours with conidias of T. rubrum, andLTA, but not when non stimulated, or stimulated with LPS (Fig 1).When keratinocytes from primary cultures of skin from healthy donors were cultivated48 hours, it was found dispersion in terms of proliferation, increase in size andgranularity when stimulated with conidias of T. rubrum, and LPS but not when nonstimulated, or stimulated with LTA (Fig 2).The keratinocytes expressed increased levels of TLR2 and TLR6 when werestimulated with LTA and less to T. rubrum, in the 6 hours cultures, but this last cells stillshowed increased size (Fig 3).The Keratinocytes expressed increased levels of TLR2 in the 48 hours cultures whenwere stimulated with LPS and T. rubrum.(Fig 4)Besides, β-defensin-2 was detected in the supernatant of cultures of keratinocytesstimulated with LPS (Fig 5).It can preliminary be concluded that keratinocytes from primary cultures of human skin from healthy donors, are cells that respond as typical immune cells, after stimulationwith T. rubrum, LTA and LPS in different conditions, and that this mechanism may bevery important, for the protection of local environment. References1.- Arenas R., Dermatofitosis en México. Rev Iberoam Micol 2002; 19: 63-67.2.- Kupper T. and Fuhlbrigge R. Immune surveillance in the skin: mechanims and clinical consecuences.Nat Rev Immunol 2004; 4: 211-2223.- Kôllish G., Naderi B., Voelcker V., Wallich R., Behrendt H., Ring J., Bauer S., Jacob T., Mempel M. andOlelrt M. Various members of the Toll-Like receptor family contribute to the innate immune response ofhuman epidermal keratinocytes. Immunology 2005; 114: 531-541.4.- Akira, S. and Takeda K. 2004. Toll-like Receptor Signalling. Nature Reviews Immunology 4:499-511. http://precedings.nature.com/documents/930/version/1 Thu, 06 Sep 2007 15:21:03 UTC Keratinocytes from human skin respond as typical immune cells after the stimulation with Trichophyton rubrum hdl:10101/npre.2007.930.1 2007-09-06 Alfonso E. Islas-Rodríguez Nature Precedings 2007-09-06T15:21:03Z Manuscript Immunology Microbiology Molecular Cell Biology http://creativecommons.org/licenses/by/2.5/