No primexine and plasma membrane undulation is essential for primexine deposition and plasma membrane undulation during microsporogenesis in Arabidopsis.

Primexine deposition and plasma membrane undulation are the initial steps of pollen wall formation. However, little is known about the genes involved in this important biological process. Here, we report a novel gene, NO PRIMEXINE AND PLASMA MEMBRANE UNDULATION (NPU), which functions in the early stage of pollen wall development in Arabidopsis (Arabidopsis thaliana). Loss of NPU function causes male sterility due to a defect in callose synthesis and sporopollenin deposition, resulting in disrupted pollen in npu mutants. Transmission electronic microscopy observation demonstrated that primexine deposition and plasma membrane undulation are completely absent in the npu mutants. NPU encodes a membrane protein with two transmembrane domains and one intracellular domain. In situ hybridization analysis revealed that NPU is strongly expressed in microspores and the tapetum during the tetrad stage. All these results together indicate that NPU plays a vital role in primexine deposition and plasma membrane undulation during early pollen wall development.

Wright's Technique with the Addition of Visualized Axial Cortical Windows in Odontoid Fractures.

This study sought to investigate and evaluate a modified axial translaminar screw fixation for treating odontoid fractures. We performed a retrospective study at Wenzhou Medical University Affiliated Second Hospital between March 2016 and June 2018. We retrospectively collected and analyzed the medical records of 23 cases with odontoid fractures. All patients were identified as type II odontoid fractures without neurological deficiency and serious diseases following the classification of Anderson. The average age, gender ratio, and body mass index (BMI) were 54.3 ± 11.1 years, 12 men to 11 women, and 22.6 ± 2.4 kg/m2 , respectively. Patients in this study accepted screw fixation using our modified axial translaminar screw fixation combined with atlas pedicle or lateral mass screw fixation. Within the technique, a small cortical "window" was dug in the middle of the axial contralateral lamina, such that the screws in the lamina were visualized to prevent incorrectly implanting the posterior spinal canal through the visualized "window." A total of 46 bone screws were accurately inserted into the axial lamina without using fluoroscopy. The length of all translaminar screws ranged between 26 and 30 mm, while the diameter was 3.5 mm. During the follow-up survey, the visual analog scale (VAS) and neck disability index (NDI) were measured. We provide a simple modification of Wright's elegant technique with the addition of "visualized windows" at the middle of the axial lamina. In all patients, screws were inserted accurately without bony breach and the screw angle was 56.1 ± 3.0°. Mean operative time was 102 ± 28 min with an average blood loss of 50 ± 25 mL. Postoperative hemoglobin and mean length of hospital stay were 12.0 ± 1.4 g/dL and 10.4 ± 3.4 days, respectively. The average follow-up time of all cases was 14.7 months and no internal fixation displacement, loosening, or breakage was found. All patients with odontoid fractures reported being satisfied with the treatment during the recheck period and good clinical outcomes were observed. At 1, 6, and 12 months, NDI and VAS showed that the symptoms of neck pain and limitations of functional disability improved significantly during follow-up. Our results suggest that the modified translaminar screw fixation technique can efficiently treat Anderson type II odontoid fracture, followed by the benefits of less soft tissue dissection, simple operation, no fluoroscopy, and accurate placement of screws.

Projection of the Most Anterior Line of the Spinal Canal on Lateral Radiograph: An Anatomic Study for Percutaneous Kyphoplasty and Percutaneous Vertebroplasty.

ABSTRACTPurpose: To measure the projection of the most anterior line of the spinal canal on lateral radiographs of the vertebra (C3-L5) and evaluate the efficacy of the safety line (SL) in preventing intraspinal cement leakage in percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). Materials and Methods: Fifteen adult dry-bone spine specimens were analyzed. The projection of the SL was viewed on lateral radiographs. The distance between the SL and the posterior vertebral body line (PVBL) was measured. Two groups of patients were treated by PKP, and cement injection was stopped either before the PBVL (group 1) or before the SL (group 2) under lateral fluoroscopy. The rate of cement leakage was compared between the two groups. Results: The largest distance between the SL and PVBL was at L1 (5.22 ± 0.62 mm). From L1 to L5, the distance decreased progressively to 1.05 ± 0.64 mm. Similar variation was also observed from L1 to T1 (0.19 ± 0.18 mm). The postoperative computed tomography scan was more sensitive and accurate in detecting intraspinal leakage than radiography in group 1 (p = 0.000); however, there was no significant difference in sensitivity or accuracy between methods in group 2 (p = 0.063). The rate of intraspinal cement leakage was significantly higher in group 1 than group 2 (p = 0.000). Conclusions: The operator should frequently check to ensure that cement injection has stopped upon reaching the SL. Surgeons may benefit from this quantitative anatomical study of PKP and PVP.

Percutaneous atlantoaxial anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion for patients with a high-riding vertebral artery.

CONTEXT/OBJECTIVE: To describe the technique and clinical results of percutaneous atlantoaxial anterior transarticular fixation combined with limited exposure posterior C1/2 arthrodesis in patients with a high-riding vertebral artery. DESIGN SETTING: Zhejiang Spine Center, China. PARTICIPANTS: Five patients with a high-riding vertebral artery and an upper cervical fracture. INTERVENTIONS: Percutaneous atlantoaxial anterior transarticular screw fixation combined with limited exposure posterior C1/2 wire fusion. OUTCOME MEASURES: Computed tomography scans were used to assess the high-riding vertebral artery and feasibility of anterior transarticular screw fixation preoperatively. A Philadelphia collar was used to immobilize the neck postoperatively. Anteroposterior (open-mouth) and lateral views were obtained at pre/postoperation and at the follow-up. RESULTS: The operation was performed successfully on all of the patients, and no intraoperative operation-related complications such as nerve injury, vertebral artery, and soft tissue complications occurred. The mean follow-up period was 33.8 months (range: 24 to 58 months). No screw breakage, loosening, pullout, or cutout was observed. Bone union was achieved in all patients at the last follow-up. CONCLUSIONS: Our small case series results suggested that percutaneous anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion is a technically minimally invasive, safe, feasible, and useful method to treat patients with a high-riding vertebral artery.

Pooled analysis of non-union, re-operation, infection, and approach related complications after anterior odontoid screw fixation.

BACKGROUND: Anterior odontoid screw fixation (AOSF) has been one of the most popular treatments for odontoid fractures. However, the true efficacy of AOSF remains unclear. In this study, we aimed to provide the pooled rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. METHODS: We searched studies that discussed complications after AOSF for type II or type III odontoid fractures. A proportion meta-analysis was done and potential sources of heterogeneity were explored by meta-regression analysis. RESULTS: Of 972 references initially identified, 63 were eligible for inclusion. 54 studies provided data regarding non-union. The pooled non-union rate was 10% (95% CI: 7%-3%). 48 citations provided re-operation information with a pooled proportion of 5% (95% CI: 3%-7%). Infection was described in 20 studies with an overall rate of 0.2% (95% CI: 0%-1.2%). The main approach related complication is postoperative dysphagia with a pooled rate of 10% (95% CI: 4%-17%). Proportions for the other approach related complications such as postoperative hoarseness (1.2%, 95% CI: 0%-3.7%), esophageal/retropharyngeal injury (0%, 95% CI: 0%-1.1%), wound hematomas (0.2%, 95% CI: 0%-1.8%), and spinal cord injury (0%, 95% CI: 0%-0.2%) were very low. Significant heterogeneities were detected when we combined the rates of non-union, re-operation, and dysphagia. Multivariate meta-regression analysis showed that old age was significantly predictive of non-union. Subgroup comparisons showed significant higher non-union rates in age ≥ 70 than that in age ≤ 40 and in age 40 to <50. Meta-regression analysis did not reveal any examined variables influencing the re-operation rate. Meta-regression analysis showed age had a significant effect on the dysphagia rate. CONCLUSIONS/SIGNIFICANCES: This study summarized the rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. Elderly patients were more likely to experience non-union and dysphagia.

[Immunolocalization of receptor activator of NF-kappaB ligand and osteoprotegerin during mouse mandibular first molar eruption].

OBJECTIVE: To investigate the immunolocalization of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG), and to explore the correlation between their expressions and activity of osteoclast during first mandibular molar eruption. METHODS: Mouse mandibles dissected from postnatal day 1.5 to 14.5 were stained respectively for multinucleated osteoclasts using tartrate-resistant acid phosphatase (TRAP) staining, and RANKL and OPG protein expression was examined by immunohistochemical staining. RESULTS: The two peak values of osteoclast/acreage in the occlusal and basal region were both observed on the P1.5 and P9.5; while the two peak values in the lateral region were on P3.5 and P9.5. During the mouse molar eruption, burst of osteoclastogenesis was associated with high expression of RANKL and low expression of OPG. CONCLUSIONS: RANKL and OPG could have a close relationship with the osteoclast activity and two developmental apexes were observed during the molar eruption. The occlusal movement was relatively stable, meanwhile the temporarily accelerative movement to the basal and lateral regions could occur.

[Effect of composite restoration on the reinforcement of teeth].

OBJECTIVE: To determine the effect of composite restoration on reinforcement of weakened tooth structure and the possible mechanism. METHODS: Sixty freshly extracted non-carious maxillary premolars were collected and divided into 6 groups with 10 specimen in each group. MOD cavities (buccolingual width: 2.8 to 3.2 mm; palatal cusp width: 2.0 mm; cusp height: 5.0 mm) were prepared individually. Group 1 was prepared and not restored (control). The other 5 groups were restored with silver amalgam alloy (group 2), Z250 without bonding (group 3), F2000 (group 4), Z250 (group 5) and Z350 nanocomposite (group 6) (3M ESPE) respectively. The fracture resistance of the tested teeth was determined by applying a vertical splitting load through a specially shaped steel rod at a crosshead speed of 1 mm/min. The data were analyzed by ANOVA. RESULTS: The average fracture resistance of the 6 groups was: (245.29 +/- 39.49) N (group 1), (255.09 +/- 42.14) N (group 2), (267.34 +/- 31.56) N (group 3), (293.90 +/- 33.42) N (group 4), (337.81 +/- 32.63) N (group 5) and (349.08 +/- 32.93) N (group 6). There was no significant difference between the group 1, group 2 and group 3. The fracture resistance of group 4, group 5 and group 6 was higher than that of group 1 and group 2 (P < 0.05). Significant difference was noted between group 5 and group 3 (P < 0.01). The fracture resistance of group 4 was much lower than that of group 5 and group 6 (P < 0.01). No significant difference was found between group 5 and group 6. CONCLUSIONS: The use of composite increased the fracture resistance of the tooth with an MOD restoration. This effect was related to the adhesive force, polymerization shrinkage stress and the elastic modulus of the composite.