Strategies to avoid internal carotid artery injury in "sandwich" atlantoaxial dislocation patients during surgery.

PURPOSE: To elucidate the anatomic relationship between the internal carotid artery (ICA) and the bony structures of the craniovertebral junction among "sandwich" atlantoaxial dislocation (AAD) patients, and to analyze the risks of injury during surgical procedures. METHODS: The distance from the medial wall of ICA to the midsagittal plane (D1), the shortest distance between the ICA wall and the anterior cortex of the lateral mass of atlas (LMA) (D2) on the most caudal and cranial levels of LMA and the angle (A) between the sagittal plane passing through the screw entry point of C1 lateral mass(C1LM) screw and the medial tangent line of the vessel passing through the entry point were measured. Besides, the location of ICA in front of the atlantoaxial vertebra was divided into 4 categories (Z1-Z4). RESULTS: There was a statistically difference between the male and female patients regarding D1, and the difference between D2 at level a and level b as well as angle A between the left and right sides were statistically different (p < 0.05). Ninety-two ICAs (57.5%) were anteriorly located in Z3, 50 (31.3%) were located in Z4, 17 were located in Z2, and only one ICA was located in Z1 in all 80 patients. CONCLUSIONS: In "sandwich" AAD patients, particular attention should be paid to excessively medialized ICA to avoid ICA injury during trans-oral procedures, and the risk of injuring the ICA with more cranially and medially angulated C1LM screw placement was relatively less during posterior fixation procedures. A novel classification of ICA location was used to describe the relationship between ICA and LMA.

Sandwich fusion of CBM9_2 to enhance xylanase thermostability and activity.

Used as model for sandwich fusion, a mesophilic Aspergillus niger GH11 xylanase (Xyn) was fused into C2-Xyn-C2 with a thermophilic Thermotaga maritima GH10 xylanase carbohydrate-binding module CBM9_2 (C2). Linearized plasmids C2-pET20b-C2-Xyn were amplified from template pET20b-Xyn-C2 with a 4.3 kb C2-pET20b megaprimer, ligated into circular plasmids in blunt-end ligation, and transformed into E. coli BL21 (DE3) cells. The C2-Xyn-C2 had optimum activity at 45 °C and pH 4.2, a 2.85 h thermal inactivation half-life at 80 °C and a 8.69 h at 50 °C, with the 8.69 h value 24.8-, 7.5-, and 7.1-fold longer than the Xyn and single terminal fusion enzymes Xyn-C2, and C2-Xyn. Thermodynamics showed that the enzyme had a 1.8 °C higher melting temperature, lower values ΔS, ΔΔG, and a denser structure than the Xyn. Kinetics showed that the C2-Xyn-C2 catalytic efficiency was 1.2-~6-fold and 2.7-~7.9-fold higher on beechwood and oat-spelt xylan than those of the enzymes Xyn, Xyn-C2, and C2-Xyn. The sandwich fusion evolved the xylanase with "armor-hands" to enhance simultaneously thermostability and activity in quality.

Expression and purification of soluble HIV-2 viral protein R (Vpr) using a sandwich-fusion protein strategy.

Viral accessory proteins of the human immunodeficiency virus (HIV), including virus protein R (Vpr), are crucial for the efficient replication of the virus in the host organism. While functional data are available for HIV-1 Vpr, there is a paucity of data describing the function and structure of HIV-2 Vpr. In this report, the construction of a His6-MBP-intein1-Vpr-intein2-Cyt b5-His6 fusion protein is presented. Unlike previous research efforts where only microgram quantities of HIV-1 Vpr could be produced, this construct enabled soluble milligram yields via an Escherichia coli over-expression system. Straightforward protein purification of HIV-2 Vpr was achieved by standard chromatography routines and autocatalytic intein cleavage. Preliminary structural studies by circular dichroism (CD) and NMR spectroscopy revealed that the protein is stable in the presence of micellar concentrations of the detergent DPC and adopts an α-helix secondary structure.