Aß stimulates microglial activation through antizyme-dependent downregulation of ornithine decarboxylase.

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorders. Its pathology is associated with the deposition of amyloid ß (Aß), an abnormal extracellular peptide. Moreover, its pathological progression is closely accompanied by neuroinflammation. Specifically, Aß-associated microglial overactivation may have the central role in AD pathogenesis. Interestingly, arginine metabolism may contribute to the equilibrium between M1 and M2 microglia. However, little is known about the involvement of arginine metabolism in Aß-induced microglial neuroinflammation and neurotoxicity. Moreover, the underlying mechanism by which Aß induces the transition of microglia to the M1 phenotype remains unclear. In this study, we investigated the role of Aß in mediating microglial activation and polarization both in vitro and in vivo. Our results demonstrated that under the Aß treatment, ornithine decarboxylase (ODC), a rate-limiting enzyme in the regulation of arginine catabolism, regulates microglial activation by altering the antizyme (AZ) + 1 ribosomal frameshift. Furthermore, the restoration of ODC protein expression levels has profound effects on inhibition of Aß-induced M1 markers and thus attenuates microglial-mediated cytotoxicity. Altogether, our findings suggested that Aß may contribute to M1-like activation by disrupting the balance between ODC and AZ in microglia.

Loading effects of anterior cervical spine fusion on adjacent segments.

Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3-C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1); and C5-C6 segments that were fused via cage-instrumented plate fixation (group 2). Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM) of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3-C4) adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress-shielding effects. Furthermore, increased stress and ROM of the adjacent segments after long-term bone fusion may accelerate degeneration in adjacent segment.

Traumatic subdural hematoma in the lumbar spine.

Traumatic spinal subdural hematoma is rare and its mechanism remains unclear. This intervention describes a patient with mental retardation who was suffering from back pain and progressive weakness of the lower limbs following a traffic accident. Magnetic resonance imaging of the spine revealed a lumbar subdural lesion. Hematoma was identified in the spinal subdural space during an operation. The muscle power of both lower limbs recovered to normal after surgery. The isolated traumatic spinal subdural hematoma was not associated with intracranial subdural hemorrhage. A spinal subdural hematoma should be considered in the differential diagnosis of spinal cord compression, especially for patients who have sustained spinal trauma. Emergency surgical decompression is usually the optimal treatment for a spinal subdural hematoma with acute deterioration and severe neurological deficits.

Evaluation of unilateral cage-instrumented fixation for lumbar spine.

BACKGROUND: To investigate how unilateral cage-instrumented posterior lumbar interbody fusion (PLIF) affects the three-dimensional flexibility in degenerative disc disease by comparing the biomechanical characteristics of unilateral and bilateral cage-instrumented PLIF. METHODS: Twelve motion segments in sheep lumbar spine specimens were tested for flexion, extension, axial rotation, and lateral bending by nondestructive flexibility test method using a nonconstrained testing apparatus. The specimens were divided into two equal groups. Group 1 received unilateral procedures while group 2 received bilateral procedures. Laminectomy, facectomy, discectomy, cage insertion and transpedicle screw insertion were performed sequentially after testing the intact status. Changes in range of motion (ROM) and neutral zone (NZ) were compared between unilateral and bilateral cage-instrumented PLIF. RESULTS: Both ROM and NZ, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF, transpedicle screw insertion procedure did not revealed a significant difference between flexion-extension, lateral bending and axial rotation direction except the ROM in the axial rotation. The bilateral group's ROM (-1.7 ± 0. 8) of axial rotation was decreased significantly after transpedicle screw insertion procedure in comparison with the unilateral group (-0.2 ± 0.1). In the unilateral cage-instrumented PLIF group, the transpedicle screw insertion procedure did not demonstrate a significant difference between right and left side in the lateral bending and axial rotation direction. CONCLUSIONS: Based on the results of this study, unilateral cage-instrumented PLIF and bilateral cage-instrumented PLIF have similar stability after transpedicle screw fixation in the sheep spine model. The unilateral approach can substantially reduce exposure requirements. It also offers the biomechanics advantage of construction using anterior column support combined with pedicle screws just as the bilateral cage-instrumented group. The unpleasant effect of couple motion resulting from inherent asymmetry was absent in the unilateral group.

Cadaveric comparison of two facial flap-harvesting techniques for alloplastic facial transplantation.

BACKGROUND: Functional and aesthetic reconstruction of severe facial deformities presents a major challenge, and the results are rarely satisfactory. Recent clinical success of composite tissue allograft transplantation and improvements in autoimmune regulation have initiated efforts to reconstruct severe facial deformities with alloplastic tissue. Few reports address the full facial flap dissection approach, where lengthy procedural times remain a limiting factor in achieving optimal graft survival. Extensive vascular anastomoses within facial tissues provide a unique opportunity to explore alternative graft harvesting strategies to optimise operative ischaemia. OBJECTIVE: The aim of the study was to shorten donor-graft harvesting time and reduce warm ischaemia. We evaluated alternative facial harvesting strategies through mock cadaveric facial transplantations. METHODS: Cadaveric dissections were performed to explore facial-scalp reconstruction alternatives. Six paired sub-superficial muscloaponeurotic system (SMAS) plane composite facial-scalp flaps were harvested using either a superficial temporal artery (STA) or a facial artery (FA) pedicle technique (Group I) or an external carotid artery (ECA) pedicle technique. Total harvesting times and lengths of vascular pedicles were measured. RESULTS: Harvesting time for a STA and FA pedicle total facial flap (mean=113min, range = 105-120 min, SD = 6 min) was shorter than that for an ECA pedicle flap (mean = 232 min, range = 225-240 min, SD = 6 min) (P<0.01). Mean pedicle lengths for the STA, the FA, the ECA, the external jugular vein, and the facial vein were 37 +/- 2.1, 35 +/- 1.8, 26 +/- 1.4, 52 +/- 3.0 and 42 +/- 2.6mm, respectively. Mean pedicle lengths for the supraorbital, supratrochlear, infraorbital, mental, and facial nerve were 15 +/- 1.5, 14 +/- 1.4, 24 +/- 1.2, 30 +/- 1.6 and 32 +/- 1.8mm, respectively. CONCLUSION: Compared with previously reported ECA pedicle total facial allograft harvesting techniques, an STA and FA pedicle flap provides a shorter harvesting time and potentially safer dissection method for facial transplantation by avoiding interference with the complicated anatomy of the carotid and submental triangle. Early graft ischaemic damage can be minimised by this harvesting technique, which significantly shortens harvesting time compared with previously described approaches, while maintaining adequate full facial perfusion.

Nasal reconstruction using a split forehead flap.

BACKGROUND: The pedicle paramedian flap is the most common method used to reconstruct the nose, but secondary operations for debulking are required. In addition, this flap is always limited in length, which makes it hard to form the distal part of the nose. In this study, the authors suggest a split forehead flap with an oblique orientation designed to overcome the disadvantages of the paramedian flap. METHODS: From their practice and review of the literature, the authors discovered that there is a cutaneous branch of the supratrochlear vessels that is set out around the orbital rim, travels subcutaneously, and has a rich anastomotic plexus with other vessels. Therefore, the authors designed a myocutaneous forehead flap with an oblique orientation to lengthen it and split it into two flaps: a muscle flap and a skin flap supplied by the supratrochlear vessels and their cutaneous branch, respectively. In six cases, the muscle flap was used to reconstruct the septum-like structure and wrap the cartilage framework; the skin flap was used to form a new nose. In five cases, the forehead flap was elevated and used as a superthin skin flap to form a new nose with distinct subunits without secondary debulking operations. RESULTS: This improved flap was used in 11 cases with 6 to 25 months of follow-up. In all cases, the authors observed the cutaneous branch of the supratrochlear vessels. All patients were satisfied with their new noses. CONCLUSIONS: This split forehead flap, with an oblique orientation design, has the advantages of achieving good restoration of nasal contour and building septum-like structures and reducing the number of operations.

Microvascular reconstruction of nasal ala using a reversed superficial temporal artery auricular flap.

Microsurgical technique allows successful transfer of an auricular flap in a one-stage procedure, using the root of the helix. Although a free composite auricular flap with the superficial temporal artery pedicle provides a good solution to repair nasal defects, its vascular pedicle is so limited that a vein graft from other area of the body is usually needed to reach the recipient site, leaving an unpleasant scar on the donor site. The authors present a reversed superficial temporal artery auricular free flap for alar reconstruction by microsurgical transfer. This technique has been performed on four patients with posttraumatic alar defects. In three patients, the reversed superficial temporal vessels of the flap were anastomosed directly with the recipient facial vessels in the nasolabial fold. In one patient, the reversed superficial temporal artery of the flap was anastomosed with the facial artery as above, its accompanying vein to the proximal stem of the superficial temporal vein by a graft taken from the excess length of the reversed superficial temporal artery pedicle because a suitable vein was not found for microvascular anastomosis in the nasolabial area. In these four patients, the size of the flap was 2.5 x 2.0-4.0 x 2.5 cm, the length of the vascular pedicle is 5-8 cm, average 6.5 cm. The reversed superficial temporal artery auricular flap offers a long vascular pedicle of the auricular free flap for microvascular anastomosis in the reconstruction of the ala of nose, delivers a good solution to the problem of the vascular pedicle shortage of the proximal superficial artery auricular flap. There is no need of vein graft from other parts of the body because the superficial temporal vessels on the temple provide not only the flap pedicle but also a source of vessel grafts. This technique may have even wider applications in other facial cutaneous defect.

Vertebral axial rotation measurement method.

This study presents a new method for measuring axial rotation of vertebra. Anatomical landmarks of the vertebral body were first recognized in X-ray film. By employing appropriate geometrical relationships, vertebral body shape parameters and a computer iteration method, the rotation angle of vertebra on the transverse plane can rapidly be obtained. A cadaver lumbar spine axial rotation-fixation device was designed to confirm the accuracy of the proposed methodology. Rotation angles on CT images were adopted as the golden standard and compared with analytical results based on X-ray films. Analytical results demonstrated that the proposed method obtained more accurate and reliable results than previous methods.