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Search Results: 1 - 10 of 246813 matches for " R. Paul Ross "
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The Effect of Projection Microstereolithographic Fabricated Implant Geometry on Myocutaneous Revascularization  [PDF]
Ross M. Clark, Kirsten N. Cicotte, Paul G. McGuire, Elizabeth L. Hedberg-Dirk, Thomas R. Howdieshell
Surgical Science (SS) , 2014, DOI: 10.4236/ss.2014.512079
Abstract: Understanding cell behavior inside three-dimensional (3D) microenvironments with controlled spatial patterning of physical and biochemical factors could provide insight into the basic biology of tissue engraftment, vascular anastomosis, and revascularization. A simple layer by layer projection microstereolithography (PμSL) method was utilized to investigate the effects of a nonporous and porous bioinert barrier on myocutaneous flap engraftment and revascularization. A cranial-based, peninsular-shaped myocutaneous flap was surgically created on the dorsum of C57Bl6 mice. Porous (SP) and nonporous (S) silicone implants were tailored to precise flap dimensions and inserted between the flap and recipient bed prior to sutured wound closure. Porous implant myocutaneous flaps became engrafted to the recipient site with complete viability. In contrast, distal cutaneous necrosis and resultant flap dehiscence was evident by day 10 in nonporous implant flap mice. Laser speckle contrast imaging demonstrated flap revascularization in (SP) mice, and markedly reduced distal flap reperfusion in (S) mice. Histologic analysis of day 10 (SP) flaps revealed granulation tissue rich in blood vessels and macrophages growing through the implant pores and robust neovascularization of the distal flap. In contrast, the nonporous implant prevented tissue communication between recipient bed and flap with lack of bridging inflammatory cells and neovasculature and resultant distal tissue necrosis. We have fabricated porous and nonporous silicone implants via a simple and inexpensive technique of PμSL. Using a graded-ischemia wound healing model, we have shown that porous implants allowed contact between flap and recipient bed resulting in proximal flap arteriogenesis and neovascularization of the distal flap. Future research will utilize variations in implant pore size, spacing, and location to gain a better understanding of the cellular and molecular mechanisms responsible for myocutaneous flap engraftment, vascular anastomosis, and revascularization.
Marine Bioactives as Functional Food Ingredients: Potential to Reduce the Incidence of Chronic Diseases
Sinéad Lordan,R. Paul Ross,Catherine Stanton
Marine Drugs , 2011, DOI: 10.3390/md9061056
Abstract: The marine environment represents a relatively untapped source of functional ingredients that can be applied to various aspects of food processing, storage, and fortification. Moreover, numerous marine-based compounds have been identified as having diverse biological activities, with some reported to interfere with the pathogenesis of diseases. Bioactive peptides isolated from fish protein hydrolysates as well as algal fucans, galactans and alginates have been shown to possess anticoagulant, anticancer and hypocholesterolemic activities. Additionally, fish oils and marine bacteria are excellent sources of omega-3 fatty acids, while crustaceans and seaweeds contain powerful antioxidants such as carotenoids and phenolic compounds. On the basis of their bioactive properties, this review focuses on the potential use of marine-derived compounds as functional food ingredients for health maintenance and the prevention of chronic diseases.
Bacteriophage-Derived Peptidase Eliminates and Prevents Staphylococcal Biofilms
Mark Fenton,Ruth Keary,Olivia McAuliffe,R. Paul Ross
International Journal of Microbiology , 2013, DOI: 10.1155/2013/625341
Abstract:
Overview of technology developments in probiotic field
Catherine Stanton,Gerald F. Fitzgerald,R. Paul Ross
Microbial Ecology in Health and Disease , 2012, DOI: 10.3402/mehd.v23i0.18561
Abstract: Probiotics are ‘live microorganisms which, when administrated in adequate amounts, confer a health benefit on the host’ (FAO/WHO, 2001). This requirement, i.e. that the probiotic bacteria must be in viable form at the time of consumption, poses a number of technical challenges from food processing perspectives. Environmental stresses encountered during food processing include acid exposure during food fermentations, extremes in temperatures encountered during drying processes, in addition to oxidative, osmotic, and food matrix stresses. Furthermore, the ingested bacteria must remain viable during gastric transit, to reach the site of action in viable form to exert the probiotic effects. This imposes further stresses, as the gastrointestinal tract is naturally designed to impede the passage of microorganisms with low pH encountered in the stomach and the detergent-like properties of bile encountered in the duodenum. A number of approaches have been investigated in order to minimise the damage caused by exposure to such stresses experienced by probiotics during food processing and gastric transit. Approaches for protection of probiotic viability during food processing and shelf life include manipulation of bacterial cell physiology, application of prelethal stress to the cultures during cell preparation, selection of appropriate drying conditions, and optimisation of reconstitution conditions after drying. Furthermore, probiotic viability losses can be minimised by selection of appropriate food carriers for their delivery to the intestine. In this respect, the composition and physical nature of the food matrix can have profound effects on the stability of live probiotics during gastric transit. Encapsulation of probiotics is another approach to positively affect viability of probiotics in some matrices. Furthermore, it is important to understand the mechanisms underlying bacterial survival in hostile environments in order to develop efficacious functional foods delivering the benefits associated with the probiotics within.
The Lantibiotic Lacticin 3147 Prevents Systemic Spread of Staphylococcus aureus in a Murine Infection Model
Clare Piper,Pat G. Casey,Colin Hill,Paul D. Cotter,R. Paul Ross
International Journal of Microbiology , 2012, DOI: 10.1155/2012/806230
Abstract: The objective of this study was to investigate the in vivo activity of the lantibiotic lacticin 3147 against the luminescent Staphylococcus aureus strain Xen 29 using a murine model. Female BALB/c mice (7 weeks old, 17 g) were divided into groups (=5) and infected with the Xen 29 strain via the intraperitoneal route at a dose of 1×106 cfu/animal. After 1.5 hr, the animals were treated subcutaneously with doses of phosphate-buffered saline (PBS; negative control) or lacticin 3147. Luminescent imaging was carried 3 and 5 hours postinfection. Mice were then sacrificed, and the levels of S. aureus Xen 29 in the liver, spleen, and kidneys were quantified. Notably, photoluminescence and culture-based analysis both revealed that lacticin 3147 successfully controlled the systemic spread of S. aureus in mice thus indicating that lacticin 3147 has potential as a chemotherapeutic agent for in vivo applications.
Genome Mining for Radical SAM Protein Determinants Reveals Multiple Sactibiotic-Like Gene Clusters
Kiera Murphy,Orla O'Sullivan,Mary C. Rea,Paul D. Cotter,R. Paul Ross,Colin Hill
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020852
Abstract: Thuricin CD is a two-component bacteriocin produced by Bacillus thuringiensis that kills a wide range of clinically significant Clostridium difficile. This bacteriocin has recently been characterized and consists of two distinct peptides, Trnβ and Trnα, which both possess 3 intrapeptide sulphur to α-carbon bridges and act synergistically. Indeed, thuricin CD and subtilosin A are the only antimicrobials known to possess these unusual structures and are known as the sactibiotics (sulplur to alpha carbon-containing antibiotics). Analysis of the thuricin CD-associated gene cluster revealed the presence of genes encoding two highly unusual SAM proteins (TrnC and TrnD) which are proposed to be responsible for these unusual post-translational modifications. On the basis of the frequently high conservation among enzymes responsible for the post-translational modification of specific antimicrobials, we performed an in silico screen for novel thuricin CD–like gene clusters using the TrnC and TrnD radical SAM proteins as driver sequences to perform an initial homology search against the complete non-redundant database. Fifteen novel thuricin CD–like gene clusters were identified, based on the presence of TrnC and TrnD homologues in the context of neighbouring genes encoding potential bacteriocin structural peptides. Moreover, metagenomic analysis revealed that TrnC or TrnD homologs are present in a variety of metagenomic environments, suggesting a widespread distribution of thuricin-like operons in a variety of environments. In-silico analysis of radical SAM proteins is sufficient to identify novel putative sactibiotic clusters.
In silico analysis highlights the frequency and diversity of type 1 lantibiotic gene clusters in genome sequenced bacteria
Alan J Marsh, Orla O'Sullivan, R Paul Ross, Paul D Cotter, Colin Hill
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-679
Abstract: In total 49 novel type 1 lantibiotic clusters were identified which unexpectedly were associated with species, genera and even phyla of bacteria which have not previously been associated with lantibiotic production.Multiple type 1 lantibiotic gene clusters were identified at a frequency that suggests that these antimicrobials are much more widespread than previously thought. These clusters represent a rich repository which can yield a large number of valuable novel antimicrobials and biosynthetic enzymes.Bacteriocins are bacterially produced peptide antibiotics. Two major classes of gram-positive bacteriocins have been recognised, Class I undergo significant post-translationally modifications while the Class II are unmodified [1,2]. The majority of the class I bacteriocins are lantibiotics; small peptides containing internal bridges resulting from the formation of (β-methyl)lanthionine residues. The structural gene encodes a ribosomally synthesised precursor prepeptide which is generically named LanA. This prepeptide contains a leader sequence at the N-terminus, which is ultimately cleaved, and a propeptide at the C-terminus. Many or all of the serine and threonine residues within the propeptide are dehydrated to form dehydroalanine (Dha) and dehydrobutyrine (Dhb), respectively. When these modified residues interact with an intrapeptide cysteine, a thioether bond is formed resulting in the formation of lanthionine (Lan, from Dha) or β-methyl lanthionine (meLan, from Dhb).The lantibiotics and lantipeptides (lanthionine containing peptides which lack antimicrobial activity) can be divided into four groups according to the nature of the enzymes which catalyse (me)Lan formation [3]. In the case of type 1 lantibiotics two enzymes are involved; LanB, the lanthionine dehydratase which catalyses the dehydration of the amino acids, and LanC, the lanthionine synthetase which catalyses thioether formation. Type 2 lantibiotics contain a single LanM enzyme which performs both fu
Intensive Mutagenesis of the Nisin Hinge Leads to the Rational Design of Enhanced Derivatives
Brian Healy, Des Field, Paula M. O’Connor, Colin Hill, Paul D. Cotter, R. Paul Ross
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079563
Abstract: Nisin A is the most extensively studied lantibiotic and has been used as a preservative by the food industry since 1953. This 34 amino acid peptide contains three dehydrated amino acids and five thioether rings. These rings, resulting from one lanthionine and four methyllanthionine bridges, confer the peptide with its unique structure. Nisin A has two mechanisms of action, with the N-terminal domain of the peptide inhibiting cell wall synthesis through lipid II binding and the C-terminal domain responsible for pore-formation. The focus of this study is the three amino acid ‘hinge’ region (N 20, M 21 and K 22) which separates these two domains and allows for conformational flexibility. As all lantibiotics are gene encoded, novel variants can be generated through manipulation of the corresponding gene. A number of derivatives in which the hinge region was altered have previously been shown to possess enhanced antimicrobial activity. Here we take this approach further by employing simultaneous, indiscriminate site-saturation mutagenesis of all three hinge residues to create a novel bank of nisin derivative producers. Screening of this bank revealed that producers of peptides with hinge regions consisting of AAK, NAI and SLS displayed enhanced bioactivity against a variety of targets. These and other results suggested a preference for small, chiral amino acids within the hinge region, leading to the design and creation of producers of peptides with hinges consisting of AAA and SAA. These producers, and the corresponding peptides, exhibited enhanced bioactivity against Lactococcus lactis HP, Streptococcus agalactiae ATCC 13813, Mycobacterium smegmatis MC2155 and Staphylococcus aureus RF122 and thus represent the first example of nisin derivatives that possess enhanced activity as a consequence of rational design.
Sequencing-Based Analysis of the Bacterial and Fungal Composition of Kefir Grains and Milks from Multiple Sources
Alan J. Marsh, Orla O’Sullivan, Colin Hill, R. Paul Ross, Paul D. Cotter
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069371
Abstract: Kefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists.
The Lantibiotic Lacticin 3147 Prevents Systemic Spread of Staphylococcus aureus in a Murine Infection Model
Clare Piper,Pat G. Casey,Colin Hill,Paul D. Cotter,R. Paul Ross
International Journal of Microbiology , 2012, DOI: 10.1155/2012/806230
Abstract: The objective of this study was to investigate the in vivo activity of the lantibiotic lacticin 3147 against the luminescent Staphylococcus aureus strain Xen 29 using a murine model. Female BALB/c mice (7 weeks old, 17?g) were divided into groups ( ) and infected with the Xen 29 strain via the intraperitoneal route at a dose of ?cfu/animal. After 1.5?hr, the animals were treated subcutaneously with doses of phosphate-buffered saline (PBS; negative control) or lacticin 3147. Luminescent imaging was carried 3 and 5 hours postinfection. Mice were then sacrificed, and the levels of S. aureus Xen 29 in the liver, spleen, and kidneys were quantified. Notably, photoluminescence and culture-based analysis both revealed that lacticin 3147 successfully controlled the systemic spread of S. aureus in mice thus indicating that lacticin 3147 has potential as a chemotherapeutic agent for in vivo applications. 1. Introduction Staphylococcus aureus is one of the most significant bacterial pathogens and can cause diseases ranging from minor and surgical site infections [1] to potentially life-threatening endocarditis [2–4] and bacteraemia [5–8]. It is a particular problem in hospitals as a consequence of the emergence and dissemination of multidrug-resistant forms such as methicillin-resistant S. aureus (MRSA), vancomycin intermediate susceptibility S. aureus (VISA), and heterogenous VISA (hVISA). The prevalence of these antibiotic resistant forms means that the discovery of novel chemotherapeutic agents to combat these pathogens is of key importance [9, 10]. The lantibiotics (lanthionine-containing antibiotics [11]) are a group of posttranslationally modified antimicrobial peptides of which nisin and lacticin 3147 are among the most extensively investigated. A number of lantibiotics have been noted to exhibit potent antimicrobial activity against staphylococci of clinical relevance. In agar diffusion assays, the type I lantibiotics epidermin, Pep5, epicidin K7, and epilancin 280 display impressive levels of activity against coagulase negative staphylococci (CNS) [12], and it has been suggested that their potential could be exploited to prevent the colonization of medical devices [12]. Nisin has also been shown on several occasions to possess significant anti-Staphylococcus activity. When tested against 20 MRSA strains, one study revealed that the minimum inhibitory concentration (MIC) of nisin A ranged between 1.5 and 16?mg/L [13], while a more recent investigation revealed MICs of 0.5–4.1?mg/L [14]. The in vitro activity of other forms of nisin (nisin F, Q, and Z)
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