Effective screening methods to prevent surgical site infections in orthopedic surgery: an observational study.

BACKGROUND: The bacterial source of surgical-site infections (SSIs) can have either endogenous and/or exogenous origins, and some studies have revealed that endogenous transmission is an important pathway for SSIs in orthopedic surgery. However, since the frequency of SSIs is low (0.5-4.7%), screening all surgery patients is labor-intensive and cost-prohibitive. The goal of this study was to better understand how to improve the efficacy of nasal culture screening in preventing SSIs. METHODS: Nasal cultures for 1616 operative patients over a 3-year period were evaluated for the presence of nasal bacterial microbiota and the species identity. We also investigated the medical factors that influence colonization and evaluated the ratio of agreement between nasal cultures and SSI-causing bacteria. RESULTS: In a survey of 1616 surgical cases, 1395 (86%) were normal microbiota (NM), 190 (12%) were MSSA carriers, and 31 (2%) were MRSA carriers. The risk factors for MRSA carriers were significantly higher than the NM group in patients with a history of hospitalization (13 [41.9%], p = 0.015), patients who had been admitted to a nursing facility (4 [12.9%], p = 0.005), and patients who were > 75 years of age (19 [61.3%], p = 0.021). The incidence of SSIs was significantly higher in the MSSA group (17/190 [8.4%]) than the NM group (10/1395 [0.7%], p = 0.00). The incidence of SSIs in the MRSA group (1/31 [3.2%]) tended to be higher than that in the NM group, but there was no statistically significant difference (p = 0.114). The concordance rate between causative bacteria of SSI and species present in nasal cultures was 53% (13/25 cases). CONCLUSIONS: The results of our study suggest screening patients with a history of past hospitalization, a history of admission in a long-term care facility, and older than 75 to reduce SSIs. TRIAL REGISTRATION: This study was approved by the institutional review board of the authors' affiliated institutions (the ethics committee of Sanmu Medical Center, 2016-02).

Dynamic Multi-projection Mapping Based on Parallel Intensity Control.

Projection mapping using multiple projectors is promising for spatial augmented reality; however, it is difficult to apply it to dynamic scenes. This is because the conventional method decides all pixel intensities of multiple images simultaneously based on the global optimization method, and it is hard to reduce the latency from motion to projection. To mitigate this, we propose a novel method of controlling the intensity based on a pixel-parallel calculation for each projector in real-time with low latency. This parallel calculation leverages the insight that the projected pixels from different projectors in overlapping areas can be approximated independently if the pixel is sufficiently small relative to the surface structure. Additionally, our pixel-parallel calculation method allows a distributed system configuration, such that the number of projectors can be increased to form a network for high scalability. We demonstrate a seamless mapping into dynamic scenes at 360 fps with a 9.5-ms latency using ten cameras and four projectors.

Parenteral formulation and thermal degradation pathways of a potent rebeccamycin based indolocarbazole topoisomerase I inhibitor.

The development of a practical and pharmaceutically acceptable parenteral dosage form of 1 is described. A cosolvent formulation strategy was selected to achieve the necessary human dose of 1 for administration via intravenous infusion. The final market formulation of 1 chosen for commercial development and Phase II clinical supplies was the topoisomerase inhibitor dissolved in a 50% aqueous propylene glycol solution vehicle with 50mM citrate buffered to pH 4. The thermal degradation pathways of 1 in this aqueous propylene glycol vehicle in the pH range of 3-5 were determined by relative kinetics and degradation product identification using LC/MS, LC/MS/MS, and NMR analysis. The primary mode of degradation of 1 in this aqueous cosolvent formulation is hydrolysis affording the anhydride 2 (in equilibrium with the dicarboxylic acid 3) and release of the hydrazine diol side chain 11. Subsequent oxidative degradation of 11 occurs in several chemical steps which yield a complicated mixture of secondary reaction products that have been structurally identified.

'Crystal lattice engineering,' an approach to engineer protein crystal contacts by creating intermolecular symmetry: crystallization and structure determination of a mutant human RNase 1 with a hydrophobic interface of leucines.

A protein crystal lattice consists of surface contact regions, where the interactions of specific groups play a key role in stabilizing the regular arrangement of the protein molecules. In an attempt to control protein incorporation in a crystal lattice, a leucine zipper-like hydrophobic interface (comprising four leucine residues) was introduced into a helical region (helix 2) of the human pancreatic ribonuclease 1 (RNase 1) that was predicted to form a suitable crystallization interface. Although crystallization of wild-type RNase 1 has not yet been reported, the RNase 1 mutant having four leucines (4L-RNase 1) was successfully crystallized under several different conditions. The crystal structures were subsequently determined by X-ray crystallography by molecular replacement using the structure of bovine RNase A. The overall structure of 4L-RNase 1 is quite similar to that of the bovine RNase A, and the introduced leucine residues formed the designed crystal interface. To characterize the role of the introduced leucine residues in crystallization of RNase 1 further, the number of leucines was reduced to three or two (3L- and 2L-RNase 1, respectively). Both mutants crystallized and a similar hydrophobic interface as in 4L-RNase 1 was observed. A related approach to engineer crystal contacts at helix 3 of RNase 1 (N4L-RNase 1) was also evaluated. N4L-RNase 1 also successfully crystallized and formed the expected hydrophobic packing interface. These results suggest that appropriate introduction of a leucine zipper-like hydrophobic interface can promote intermolecular symmetry for more efficient protein crystallization in crystal lattice engineering efforts.

Characterization of hydrazine derivative: proposed decomposition mechanism and structure elucidation of decomposition compounds.

Decomposition of protected hydrazine diol (1) hemi-oxalate, a key intermediate of the potent indolocarbazole-based DNA topoisomerase I inhibitor (2), was investigated. Spectroscopic analysis revealed that the main decomposition compounds of the hydrazine derivative were a peroxide (3) and an alcohol derivative (4). The peroxide derivative (3) was proposed to form in the presence of oxygen- and/or H(2)O-generated radicals, which was subsequently reduced to the more stable alcohol derivative (4). A plausible decomposition mechanism was proposed and our findings were substantiated by chemical conversion.

A novel binding assay for metabotropic glutamate receptors using [3H] L-quisqualic acid and recombinant receptors.

We established a methodology to analyze radioligand binding to the recombinant type la metabotropic glutamate receptor (mGluRla). A full-length cDNA encoding mGluR1a, which was isolated from a lambda gt 11 cDNA library of human cerebellar origin, was expressed in a baculovirus/Sf9 insect cell system. Membrane fractions with recombinant receptor expression were analyzed for the binding of [3H]L-quisqualic acid (L-QA), which is known to be a potent agonist of mGluRla. Efficient binding of the radioligand to the human receptor was observed in a saturable manner, giving an apparent Kd= 0.091 microM. [3H]L-QA bound to the human mGluR1a was displaced by known ligands such as L-QA, L-Glu, t-ACPD ((+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid) with IC50s = 0.056, 0.97 and 4.0 microM, respectively. MCPG (alpha-methyl-4-carboxyphenylglycine) displaced the radioligand binding with lower potency. Using this binding protocol, we then evaluated the ligand ability of synthetic dipeptides. Among peptides tested, only Glu-containing dipeptides inhibited the radioligand binding, e.g. IC50 of L-Met-L-Glu was 4.3 microM. When phosphatidyl inositol turnover was assayed in mGluR1a-expressing CHO cells, L-Met-L-Glu was partially agonistic. We further expanded this [3H]L-QA binding protocol to type 5a mGluR, another member of group I mGluRs, as well as to AMPA receptor, a member of ionotropic glutamate receptors, since L-QA is also known to be a potent ligand for these receptors. Data shown here will provide a novel system not only to search for ligands for the glutamate receptors, but also to biochemically analyze the interaction modes between glutamate receptors and their ligands.