Potential use of diffusion tensor imaging in level diagnosis of multilevel cervical spondylotic myelopathy

STUDY DESIGN.: A prospective study on a series of consecutive patients. OBJECTIVE.: To investigate the use of diffusion tensor imaging (DTI) and orientation entropy in level localization in patients diagnosed with multilevel cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA.: Multilevel CSM presents complex neurological signs that make level localization difficult. DTI is recently found to be able to assess the microstructural changes of the white matter caused by cord compression. METHODS.: Sixteen patients with CSM with multilevel compression were recruited. The level(s) responsible for the clinical symptoms were determined by detailed neurological examination, T2-weighted (T2W) magnetic resonance imaging (MRI), and DTI. On T2W MRI, anterior-posterior compression ratio and increased signal intensities were used to determine the affected level(s). The level diagnosis results from T2W MRI, increased signal intensities, DTI, and combination method were correlated to that of neurological examination on a level-to-level basis, respectively. The accuracy, sensitivity, and specificity were calculated. RESULTS.: When correlated with the clinical level determination, the weighted orientation entropy-based DTI analysis was found to have higher accuracy (82.76% vs. 75.86%) and sensitivity (84.62% vs. 76.92%) than those of the anterior-posterior compression ratio. The increased signal intensities have the highest specificity (100.00%) but the lowest accuracy (58.62%) and sensitivity (53.85%). When combined with the level diagnosis result of wOE with that of anterior-posterior compression ratio, it demonstrated the highest accuracy and sensitivity that were 93.10% and 96.15%, respectively, and equal specificity (66.67%) with using them individually. CONCLUSION.: DTI can be a useful tool to determine the pathological spinal cord levels in multilevel CSM. This information from orientation entropy-based DTI analysis, in addition to conventional MRI and clinical neurological assessment, should help spine surgeons in deciding the optimal surgical strategy. Copyright © 2014 Lippincott Williams & Wilkins.postprin

Quantitative assessment of column-specific degeneration in cervical spondylotic myelopathy based on diffusion tensor tractography

Purpose Cervical spondylotic myelopathy (CSM) is a common spinal cord disorder in the elderly. Diffusion tensor imaging (DTI) has been shown to be of great value for evaluating the microstructure of nerve tracts in the spinal cord. Currently, the quantitative assessment of the degeneration on the specific tracts in CSM is still rare. The aim of the present study was to use tractography-based quantification to investigate the column-specific degeneration in CSM. Methods A total of 43 volunteers were recruited with written informed consent, including 20 healthy subjects and 23 CSM patients. Diffusion MRI was taken by 3T MRI scanner. Fiber tractography was performed using TrackVis to reconstruct the white matter tracts of the anterior, lateral and posterior column on the bilateral sides. The DTI metrics acquired from tractography, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD), were compared between healthy subjects and CSM patients. Results Compared to healthy subjects, FA was found significantly lower in the lateral (Healthy 0.64 ± 0.07 vs. CSM 0.53 ± 0.08) and posterior column (Healthy 0.67 ± 0.08 vs. CSM 0.47 ± 0.08) (p < 0.001), while MD, AD and RD were significantly higher in the anterior, lateral and posterior column in CSM (p < 0.05). Conclusion Loss of microstructural integrity was detected in the lateral and posterior column in CSM. Tractography-based quantification was capable of evaluating the subtle pathological insult within white matter on a column-specific basis, which exhibited potential clinical value for in vivo evaluation of the severity of CSM. © 2014 Springer-Verlag Berlin Heidelberg.postprin

Argon 1s(-2) Auger hypersatellites

The 1s(-2) Auger hypersatellite spectrum of argon is studied experimentally and theoretically. In total, three transitions to the final states 1s(-1)2p(-2)(S-2(e),D-2(e)) and 1s(-1)2s(-1)(S-1)2p(-1)(P-2(o)) are experimentally observed. The lifetime broadening of the 1s(-2) -> 1s(-1)2p(-2)(S-2(e),D-2(e)) states is determined to be 2.1(4) eV. For the used photon energy of h nu = 7500 eV a KK/K ionisation ratio of 2.5(3) x 10(-4) is derived. Generally, a good agreement between the experimental and present theoretical energy positions, linewidths, and intensities is obtained

Advances in Strain Improvement for the Production of ε-Poly-L-lysine

ε-Poly-L-lysine (ε-PL) is a novel biopolymer consisting of 25–35 L-lysine residues, which is formed by the dehydration condensation of ε-NH2 and α-COOH. ε-PL possesses many excellent characteristics, such as antimicrobial activity, edibility, water solubility, biodegradability, thermostability and nontoxicity. As a natural and safe food preservative, ε-PL possesses many excellent advantages such as thermal stability, edibility, water solubility, degradability, and broad-spectrum antibacterial activity and has been successfully utilized in Japan, South Korea, the United States, China and other countries. ε-PL is usually produced by fermentation with Streptomyces albulus, and improving ε-PL-producing stains is crucial for enhancing ε-PL production and reducing costs. At present, researchers have obtained microbial strains capable of producing high levels of ε-PL by using physicochemical mutagenesis, ribosome engineering, genome shuffling, genetic engineering and other methods. This review introduces the mechanism of ε-PL biosynthesis and recent progress in strain improvement for the production of ε-PL, and gives an overview of the fermentation process of ε-PL. Finally, this review concludes with an outlook on future research directions. We hope that this review can help promote strain improvement for green biological manufacturing of ε-poly-L-lysine