Comparison of 3D-printed Titanium Alloy and Polyether Ether Ketone Prosthetic Beaks for an Injured Red-crowned Crane (Grus japonensis).

The red-crowned crane (Grus japonensis) is a critically endangered species. Three-dimensional-printed prosthetic beaks made of titanium alloy and polyether ether ketone (PEEK) were used to repair the beak of a red-crowned crane that had a complete fracture of the anterior maxillary bone and rhinotheca. The physical properties and stability of the prostheses and changes in the crane's behaviors after application of either beak were evaluated. The titanium alloy and PEEK prosthetic beaks weighed 30.81 g and 5.9 g, respectively. Scanning electron microscopy showed differences in microstructure between the 2 materials and the true beak; the true beak was softer than both materials from which the prostheses were made. The titanium beak frequently detached, and the residual natural beak showed significant cuticle softening with this prosthetic beak. The titanium beak detached within an approximately 3-month period after placement, whereas the PEEK prosthetic beak has remained secure for 2 years. Moreover, the crane's foraging times (P < .01) and grooming times (P < .05) with the titanium alloy false beak were lower than the normal, red-crowned crane. With the PEEK beak, no detachment or cuticle softening occurred, and foraging and grooming behaviors were evaluated by the investigators as natural (P > .05). Based on the results of this clinical case, the PEEK prosthetic beak was found to be superior to the titanium alloy prosthetic beak in color, weight, firmness, and postoperative effects.

Virulent and Vaccine Strains of Streptococcus equi ssp. zooepidemicus Have Different Influences on Phagocytosis and Cytokine Secretion of Macrophages.

Swine streptococcosis is a significant threat to the Chinese pig industry, and Streptococcus equi ssp. zooepidemicus (SEZ) is one of the major pathogens. SEZ ATCC35246 is a classical virulent strain, while SEZ ST171 is a Chinese attenuated vaccine strain. In this study, we employed stable isotope labeling by amino acids in cell culture and liquid chromatography-mass spectrometry (LC-MS) to determine the differential response of macrophages to infection by these two strains. Eighty-seven upregulated proteins and 135 downregulated proteins were identified. The proteomic results were verified by real-time polymerase chain reaction for 10 chosen genes and Western blotting for three proteins. All differentially abundant proteins were analyzed for their Gene Ontology and Kyoto Encyclopedia of Genes and Genomes annotations. Certain downregulated proteins were associated with immunity functions, and the upregulated proteins were related to cytomembrane and cytoskeleton regulation. The phagocytosis rate and cytokine genes transcription in Raw264.7 cells during SEZ ATCC35246 and ST171 infection were detected to confirm the bioinformatics results. These results showed that different effects on macrophage phagocytosis and cytokine expression might explain the different phenotypes of SEZ ATCC35246 and ST171 infection. This research provided clues to the mechanisms of host immunity responses to SEZ ST171and SEZ ATCC35246, which could identify potential therapy and vaccine development targets.

SILAC and LC-MS/MS identification of Streptococcus equi ssp. zooepidemicus proteins that contribute to mouse brain microvascular endothelial cell infection.

Streptococcus equi ssp. zooepidemicus (SEZ) causes meningitis in both humans and animals. Some dissociative proteins of SEZ are cytotoxic to mouse brain microvascular endothelial cells (mBMECs) and may contribute to the penetration of SEZ across the blood-brain barrier (BBB). In this study, the ability of SEZ to penetrate across an in vitro BBB model was confirmed. We used stable isotope labeling with amino acids in cell culture (SILAC) to label SEZ proteins with heavy or light isotope-tagged amino acids, along with LC-MS/MS to determine which SEZ proteins were involved in interactions with mBMECs. The efficiency of SEZ protein isotope labeling was 94.7 %, which was sufficient for further analysis. Forty-nine labeled peptides were identified as binding to mBMECs, which matched to 25 SEZ proteins. Bioinformatic analysis indicated that most of these proteins were cytoplasmic. These proteins may have functions in breaching the host BBB, and some of them are known virulence factors in other bacteria. Indirect immunofluorescence results indicated that SEZ enolase had binding activity toward mBMECs. Protective test results showed that enolase was a protective antigen against SEZ infection. This research is the first application of SILAC combined with LC-MS/MS to identify SEZ proteins that may contribute to the infection of mBMECs and potentially show functions related to breaching the BBB. The outcomes provide many future avenues for research into the mechanism of SEZ-induced meningitis.

In vitro biofilm forming potential of Streptococcus suis isolated from human and swine in China

Streptococcus suis is a swine pathogen and also a zoonotic agent. The formation of biofilms allows S. suis to become persistent colonizers and resist clearance by the host immune system and antibiotics. In this study, biofilm forming potentials of various S. suis strains were characterized by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and tissue culture plates stained with crystal violet. In addition, the effects of five antimicrobial agents on biofilm formation were assayed in this study. S. suis produced biofilms on smooth and rough surface. The nutritional contents including glucose and NaCl in the growth medium modulated biofilm formation. There was a significant difference in their biofilm-forming ability among all 46 S. suis strains. The biofilm-forming potential of S. suis serotype 9 was stronger than type 2 and all other types. However, biofilm formation was inhibited by five commonly used antimicrobial agents, penicillin, erythromycin, azithromycin, ciprofloxacin, and ofloxacin at subinhibitory concentrations, among which inhibition of ciprofloxacin and ofloxacin was stronger than that of other three antimicrobial agents.Our study provides a detailed analysis of biofilm formation potential in S. suis, which is a step towards understanding its role in pathogenesis, and eventually lead to a better understanding of how to eradicate S. suis growing as biofilms with antibiotic therapy.

In vitro biofilm forming potential of Streptococcus suis isolated from human and swine in China.

Streptococcus suis is a swine pathogen and also a zoonotic agent. The formation of biofilms allows S. suis to become persistent colonizers and resist clearance by the host immune system and antibiotics. In this study, biofilm forming potentials of various S. suis strains were characterized by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and tissue culture plates stained with crystal violet. In addition, the effects of five antimicrobial agents on biofilm formation were assayed in this study. S. suis produced biofilms on smooth and rough surface. The nutritional contents including glucose and NaCl in the growth medium modulated biofilm formation. There was a significant difference in their biofilm-forming ability among all 46 S. suis strains. The biofilm-forming potential of S. suis serotype 9 was stronger than type 2 and all other types. However, biofilm formation was inhibited by five commonly used antimicrobial agents, penicillin, erythromycin, azithromycin, ciprofloxacin, and ofloxacin at subinhibitory concentrations, among which inhibition of ciprofloxacin and ofloxacin was stronger than that of other three antimicrobial agents.Our study provides a detailed analysis of biofilm formation potential in S. suis, which is a step towards understanding its role in pathogenesis, and eventually lead to a better understanding of how to eradicate S. suis growing as biofilms with antibiotic therapy.

[Construction of a stx2 deletion mutant of Shiga toxin 2 phage phiMin27 and its infectious properties].

OBJECTIVE: To construct an stx2 gene mutant phage phi Min27(delta stx::cat) and to observe its infectiousness of various serotypes Escherichia coli strains. METHODS: With the help of Red recombinant system, the stx2 gene of the E. coli O157:H7 Min27 strain isolated from intestinal feces of piglet with diarrhea at a swine farm of Shanghai, was replaced by the chloramphenicol acetyltrasferase (cat) gene from plasmid pLacI. Phage phi Min27(delta stx::cat) was isolated after induction of E. coli Min27(delta stx::cat) strain with mitomycin C. Twenty-one E. coli strains with various serotypes were infected with phi Min27(delta stx::cat), and plaque formation and lysogenic conversion of them were investigated. RESULTS: Of the 21 E. coli isolates, 2 with the serotypes of O60 and O138 integrated the phi Min27(delta stx::cat) in their chromosomes and expressed resistance to chloramphenicol. With the exception of one laboratory E. coli strain MG1655, none of the tested E. coli strains supported the formation of plaques and lysogenization when used as indicators for phi Min27(delta stx::cat). Following induction with mitomycin C, these lysogenic strains released infectious particles of phi Min27(delta stx::cat) that formed plaques on a lawn of E.coli laboratory strain MC1061. CONCLUSION: These results demonstrated that phi Min27(delta stx::cat) was able to infect and lysogenize particular E. coli strains and that the lysogens could produce infectious phage progeny. It could be inferred that Stx bacteriophages were able to spread exogenous genes among E. coli strains. The work provided a basis for further study on mechanisms of Stx phages infection and control of Stx expression.