Search results for "microbial"

Influence of different biomaterials on the viability of Aggregatibacter actinomycetemcomitans

2011

Abstract Objectives The aim of the present in vitro study was to evaluate the effects of different biomaterials used for regenerative periodontal surgery on the growth of the periodontopathogen Aggregatibacter actinomycetemcomitans . Methods Three commercially available biomaterials of synthetic origin (hydroxyapatite/beta-tricalcium phosphate, nanostructured hydroxyapatite paste, oily calcium hydroxide suspension), a bovine-derived xenograft as well as an enamel matrix derivative (EMD) were added in different concentrations to calibrated suspensions of A. actinomycetemcomitans ATCC 43718/33384 (serotype b/c). Equal aliquots (0.1 ml) for the viability assay were taken after 5 min, 1 h, 3 h,…

Ultrastructural evidence of collagenolytic activity in ductal infiltrating carcinoma of the human breast

1987

The stroma of ductal infiltrating carcinoma of the human breast shows characteristic and localized areas of collagen rarefaction and fragmentation. This finding has been correlated with a peculiar type of fibrillar damage, observed in a small percentage of collagen fibrils isolated in the native state from the tumour stroma. The same pattern of lesion has been reproduced in vitro by human collagenase digestion on reconstituted fibrils. No effect has been detected by other nonspecific proteases in the same system.

Evolutionary convergence and nitrogen metabolism in Blattabacterium strain Bge, primary endosymbiont of the cockroach Blattella germanica.

2009

Bacterial endosymbionts of insects play a central role in upgrading the diet of their hosts. In certain cases, such as aphids and tsetse flies, endosymbionts complement the metabolic capacity of hosts living on nutrient-deficient diets, while the bacteria harbored by omnivorous carpenter ants are involved in nitrogen recycling. In this study, we describe the genome sequence and inferred metabolism of Blattabacterium strain Bge, the primary Flavobacteria endosymbiont of the omnivorous German cockroach Blattella germanica. Through comparative genomics with other insect endosymbionts and free-living Flavobacteria we reveal that Blattabacterium strain Bge shares the same distribution of functio…

The Fitness Effects of Random Mutations in Single-Stranded DNA and RNA Bacteriophages

2009

Mutational fitness effects can be measured with relatively high accuracy in viruses due to their small genome size, which facilitates full-length sequencing and genetic manipulation. Previous work has shown that animal and plant RNA viruses are very sensitive to mutation. Here, we characterize mutational fitness effects in single-stranded (ss) DNA and ssRNA bacterial viruses. First, we performed a mutation-accumulation experiment in which we subjected three ssDNA (ΦX174, G4, F1) and three ssRNA phages (Qβ, MS2, and SP) to plaque-to-plaque transfers and chemical mutagenesis. Genome sequencing and growth assays indicated that the average fitness effect of the accumulated mutations was similar…

Experimental evolution of an oncolytic vesicular stomatitis virus with increased selectivity for p53-deficient cells

2014

Experimental evolution has been used for various biotechnological applications including protein and microbial cell engineering, but less commonly in the field of oncolytic virotherapy. Here, we sought to adapt a rapidly evolving RNA virus to cells deficient for the tumor suppressor gene p53, a hallmark of cancer cells. To achieve this goal, we established four independent evolution lines of the vesicular stomatitis virus (VSV) in p53-knockout mouse embryonic fibroblasts (p53-/- MEFs) under conditions favoring the action of natural selection. We found that some evolved viruses showed increased fitness and cytotoxicity in p53-/- cells but not in isogenic p53+/+ cells, indicating gene-specifi…

Efficacy of poly(lactic acid)/carvacrol electrospun membranes against Staphylococcus aureus and Candida albicans in single and mixed cultures

2018

Carvacrol (CAR) is one of the most promising essential oil components with antimicrobial activity. New technologies aimed to incorporate this active molecule into carrier matrix to improve the stability and prolong the biological activity. The goal of this study was to investigate the feasibility of incorporating CAR into electrospun membranes of poly(lactic acid) (PLA) for potential applications as active antimicrobial system. To this end, PLA membranes containing homogeneously dispersed CAR were successfully prepared and a series of systematic tests including morpho-mechanical properties, in vitro release rate, and antimicrobial/antibiofilm activities against Staphylococcus aureus and Can…

Being candid about Candida airway colonization and clinical outcomes: What can we really learn from unadjusted associations?

2020

Carbapenem-Susceptible OXA-23-Producing Proteus mirabilis in the French Community

2019

International audience; Nineteen Proteus mirabilis isolates producing the carbapenemase OXA-23 were recovered over a 2-year period in 19 French hospitalized patients, of whom 12 had community onset infections. The isolates exhibited a slightly reduced susceptibility to carbapenems. Whole-genome analysis revealed that all 19 isolates formed a cluster compared to 149 other P. mirabilis isolates. Because of its susceptibility to carbapenems, this clone may be misidentified as a penicillinase producer while it constitutes a reservoir of the OXA-23-encoding gene in the community.

Geochemical evidence for arsenic cycling in living microbialites of a High Altitude Andean Lake (Laguna Diamante, Argentina)

2020

Arsenic is best known as an environmental toxin, but this element could also serve as a metabolic energy source to certain microorganisms. Moreover, As cycling may have driven microbial life on early Earth prior to oxygenation of the atmosphere. Still, little is known about the arsenic cycling processes occurring in the presence of microorganisms and the possible traces that could be preserved in the rock record. To advance our understanding of this we studied the geochemical proxies of microbial As metabolism in living microbialites from Laguna Diamante, a likely Precambrian ecosystem analogue (Catamarca, Argentina). In this study, we show that the coexistence of As(III) and As(V) strongly…

In vitro efficacy of a Hydrophilic Central Venous Catheter Loaded with Silver to Prevent Microbial Colonization

1998

A method was developed to load the surface of a central venous catheter with silver to prevent bacterial colonization. Silver confers a broad antimicrobial activity with a relatively low risk of resistance. Catheters were incubated with a silver nitrate solution in different concentrations. The solvent, incubation temperature and incubation period were varied to examine the influence on the catheter loading. With increasing incubation temperature, time and concentration of silver nitrate, higher rates of silver elution were observed by atomic absorption spectroscopy. Furthermore, by using ethanol-water as a solvent instead of pure water, the amount of silver bound to the catheter surface wa…