Integrating silver compounds and nanoparticles into ceria nanocontainers for antimicrobial applications.

Silver compounds and nanoparticles (NPs) are gaining increasing interest in medical applications, specifically in the treatment and prevention of biomaterial-related infections. However, the silver release from these materials, resulting in a limited antimicrobial activity, is often difficult to control. In this paper, ceria nanocontainers were synthesized by a template-assisted method and were then used to encapsulate silver nitrate (AgNO3/CeO2 nanocontainers). Over the first 30 days, a significant level of silver was released, as determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). A novel type of ceria container containing silver NPs (AgNP/CeO2 containers) was also developed using two different template removal methods. The presence of AgNPs was confirmed both on the surface and in the interior of the ceria containers by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Upon removal of the template by calcination, the silver was released over a period exceeding three months (>90 days). However, when the template was removed by dissolution, the silver release was shortened to ≤14 days. The antimicrobial activity of the silver-containing CeO2 containers was observed and the minimum bactericidal concentration (MBC) was determined using the broth dilution method. Investigation on human cells, using a model epithelial barrier cell type (A549 cells), highlighted that all three samples induced a heightened cytotoxicity leading to cell death when exposed to all containers in their raw form. This was attributed to the surface roughness of the CeO2 nanocontainers and the kinetics of the silver release from the AgNO3/CeO2 and AgNP/CeO2 nanocontainers. In conclusion, despite the need for further emphasis on their biocompatibility, the concept of the AgNP/CeO2 nanocontainers offers a potentially alternative long-term antibactericidal strategy for implant materials.

Bilateral traumatic hip dislocation.

An unusual bilateral hip dislocation in a 19-year-old female is presented, with a left Type III posterior fracture-dislocation (Thompson and Epstein) and a right Type V posterior dislocation (Thompson and Epstein's classification as modified by Pipkin's criteria). Open treatment with screw fixation, and removal of a fragment of the right femoral head that had been sheared off, avoided a long period of immobilization in this young woman.

Complications following iliac crest bone grafting.

Avulsion of the anterior superior iliac spine occurred after procurement of bicortical bone grafts from the anterior superior iliac crest area in two patients. The defect in the anterior ilium with a weak spike of bone created a significant stress riser and led to avulsion of the anterior superior iliac spine by the action of the sartorius and tensor fascia lata. Bicortical grafts should be taken from areas as much as 5 cm posterior to the anterior superior iliac spine to avoid this complication.

Dorsal-ventral differentiation in Simonsiella and other aspects of its morphology and ultrastructure.

The morphology and ultrastructure of the aerobic, Gram-negative multicellular-filamentous bacteria of the genus simonsiella were investigated by scanning and transmission electron microscopy. The flat, ribbon-shaped, multicellular filaments show dorsal-ventral differentiation with respect to their orientations to solid substrata. The dorsal surface, orientated away from the substrate, is convex and possesses an unstructured capsule. The ventral surface, on which the organisms adhere and glide, is concave and has an extracellular layer with fibrils extending at right angles from the cell wall. The cytoplasm in the ventral region contains a proliferation of intracytoplasmic membranes and few ribosomes in comparison to the cytoplasm in other parts of the cell. Centripetal cell wall formation is asymmetrical and commences preferentially in the ventral region. Quantitative differences in morphology and cytology exist among selected Simonsiella strains. Functional aspects of this dorsal-ventral differentiation are discussed with respect to the colonization and adherence of Simonsiella to mucosal squamous epithelial cells in its ecological habitat, the oral cavities of warm-blooded vertebrates.

Fatty acid composition of Simonsiella strains.

Gas-liquid chromatography of methyl esters of bound fatty acids extracted from the cells of 48 Simonsiella strains showed that these aerobic, gliding, multicellular-filamentous bacteria have fatty acid profiles of the pattern considered typical of Gram-negative eubacteria. All strains contained predominantly tetradecanoic acid (29.5%), 9-hexadecenoic acid (22.2%), an unidentified acid with an equivalent chain length of approximately 20 carbon atoms (15.8%), and dodecanoic acid (11.4%). Discriminant analysis of the mean relative percentages of 12 fatty acids correctly assigned 94% of the strains to groups based on their source of origin (i.e., the oral cavities of sheep, cat, human or dog); the relative amounts of only 3 of the fatty acids (9-octadecenoic acid, hexadecanoic acid, and tetradecanoic acid) provided most of this discrimination.

Incidence of Simonsiella in the oral cavity of dogs.

The gliding bacterium Simonsiella (Cytophagales, Simonsiellaceae) was found in palate samples from 66 out of 67 dogs. It is considered a common resident in the oral cavities of dogs.

Statistical association of dietary components with Simonsiella species residing in normal human mouths.

Members of the genus Simonsiella, aerobic, multicellular filamentous gliding bacteria, were detected in swabbings from the palates of 32% of 212 human subjects free of gross oral pathologies. Nutritional evaluations for 142 of the subjects showed a significantly greater daily intake among 53 Simonsiella carriers for 13 dietary variables, including four fat components, but there was no significantly greater daily intake for any of the carbohydrate components. Overall, there was a general excess dietary intake by Simonsiella carriers. The mean dietary intake of the carriers was numerically greater than that of the noncarriers for 70 of 74 dietary variables.

Deoxyribonucleic acid base composition of Simonsiellaceae.

The molar percentages of guanine plus cytosine in the DNA of 51 strains of Simonsiellaceae were determined by buoyant density ultracentrifugation of cell lysates in CsCl. The DNA base ratios ranged from 41-55 mole-% guanine plus cytosine. These values fall within the range known for the Order Cytophagales, the non-fruiting gliding bacteria, and are outside the range of the Order Myxobacterales, the fruiting myxobacteria. Among the strains of the genus Simonsiella, four distinct group can be delineated on the basis of source of origin (sheep, dog, cat, human) and GC content. The neotype of Alysiella filiformis has a GC content of 45.4 mole-%.

Isolation, characterization, and numerical taxonomy of Simonsiella strains from the oral cavities of cats, dogs, sheep, and humans.

Forty-nine strains of the gliding prokaryote Simonsiella were isolated from the oral cavities of cats (8), dogs (19), sheep (4), and humans (18) in Southern California by a direct isolation procedure using a complex serum-enriched medium. The numerical taxonomic analysis (unweighted pair-group method using arithmetric averages) of 57 differential traits for each strain was based on standard bacteriological diagnostic tests and included the molar guanine-plus-cytosine contents of the DNA and the relative percentages of fatty acid contents reported earlier. The resulting phenogram clustered the strains of Simonsiella into groups that correlated with sources of origin. The study included the neotype strain of Simonsiella crassa (ATCC 27504, ICPB 3651, NCTC 10283) of Australian sheep origin. The strains isolated from dogs, sheep, and humans form clusters of organisms that appear to have become adapted to live in and possibly to have evolved with their respective "hosts". In our judgment, these source-of-origin clusters represent different "ecospecies".