Modulating the Fluorescence of Silver Nanoclusters Wrapped in DNA Hairpin Loops via Confined Strand Displacement and Transient Concatenate Ligation for Amplifiable Biosensing.

It is intriguing to modulate the fluorescence emission of DNA-scaffolded silver nanoclusters (AgNCs) via confined strand displacement and transient concatenate ligation for amplifiable biosensing of a DNA segment related to SARS-CoV-2 (s2DNA). Herein, three stem-loop structural hairpins for signaling, recognizing, and assisting are designed to assemble a variant three-way DNA device (3WDD) with the aid of two linkers, in which orange-emitting AgNC (oAgNC) is stably clustered and populated in the closed loop of a hairpin reporter. The presence of s2DNA initiates the toehold-mediated strand displacement that is confined in this 3WDD for repeatable recycling amplification, outputting numerous hybrid DNA-duplex conformers that are implemented for a transient "head-tail-head" tandem ligation one by one. As a result, the oAgNC-hosted hairpin loops are quickly opened in loose coil motifs, bringing a significant fluorescence decay of multiple clusters dependent on s2DNA. Demonstrations and understanding of the tunable spectral performance of a hairpin loop-wrapped AgNC via switching 3WDD conformation would be highly beneficial to open a new avenue for applicable biosensing, bioanalysis, or clinical diagnostics.

Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay.

Designing antibody-powered DNA nanodevice switches is crucial and fascinating to perform a variety of functions in response to specific antibodies as regulatory inputs, achieving highly sensitive detection by integration with simple amplified methods. In this work, we report a unique DNA-based conformational switch, powered by a targeted anti-digoxin mouse monoclonal antibody (anti-Dig) as a model, to rationally initiate the hybridization chain reaction (HCR) for enzyme-free signal amplification. As a proof-of-concept, both a fluorophore Cy3-labeled reporter hairpin (RH) in the 3' terminus and a single-stranded helper DNA (HS) were individually hybridized with a recognition single-stranded DNA (RS) modified with Dig hapten, while the unpaired loop of RH was hybridized with the exposed 3'-toehold of HS, isothermally self-assembling an intermediate metastable DNA structure. The introduction of target anti-Dig drove the concurrent conjugation with two tethered Dig haptens, powering the directional switch of this DNA structure into a stable conformation. In this case, the unlocked 3'-stem of RH was implemented to unfold the 5'-stem of the BHQ-2-labeled quench hairpin (QH), rationally initiating the HCR between them by the overlapping complementary hybridization. As a result, numerous pairs of Cy3 and BHQ-2 in the formed long double helix were located in spatial proximity. In response to this, the significant quenching of the fluorescence intensity of Cy3 by BHQ-2 was dependent on the variable concentration of anti-Dig, achieving a highly sensitive quantification down to the picomolar level based on a simplified protocol integrated with enzyme-free amplification.

Using the lamina nutrient foramen as the entry point for posterior cervical pedicle screw placement.

STUDY DESIGN: A prospective study and technique description. OBJECTIVE: This study introduced a method for posterior cervical pedicle screw placement by using the bilateral posterior lamina nutrient foramens as the entry point. METHODS: Firstly, 30 dry C3-C7 vertebrae specimens were harvested for measurement. The lamina nutrient foramens were used as the entry points for posterior cervical pedicle screw placement and four linear and two angle parameters were obtained from a computed tomography scan(CT). Then, 60 patients who underwent C3-C7 pedicle screw fixation using this method were included, linear and angle parameters were obtained from a postoperative CT. RESULTS: The average incidences of lamina nutrient foramen on the C3-C7 specimens were 88.3%, 90.0%, 95.0%, 95.0%, and 96.7%, respectively. The distances from the entry point to the pedicle screw tip (OD), the pedicle transverse angles (α), and the pedicle sagittal angles (ß) measure for the entry points from C3-C7 were 28.74 ± 3.45-30.15 ± 2.01 mm, 26.88 ± 6.89° to 32.72 ± 5.91°, and 12.48 ± 9.31° to 19.71 ± 8.45°, respectively, with no significant differences between the left and right sides. In the 60 patients who underwent surgery, the lengths of the pedicle screws (PL) were 28.34 ± 2.25-30.15 ± 2.31 mm, the pedicle transverse angles (α) were 26.89 ± 6.86° to 32.36 ± 5.65°, and the pedicle sagittal angles (ß) were 12.49 ± 9.11° to 20.06 ± 8.91°. The new method had a 96.8% (454/469) success rate among these patients, with no screws penetrating the spinal canal or signs of vertebral artery injury. CONCLUSION: Entry at the bilateral lamina nutrient foramen represents an alternative posterior cervical pedicle screw placement technique that is feasible and safe.

Risk Factors for Surgical Site Infection After Posterior Lumbar Spinal Surgery.

STUDY DESIGN: A retrospective study. OBJECTIVE: The purpose of this study was to identify the independent risk factors for postoperative surgical site infection (SSI) after posterior lumbar spinal surgery based on the perioperative factors analysis. SUMMARY OF BACKGROUND DATA: SSI is one of the most common complications after spinal surgery. Previous studies have identified different risk factors for postoperative SSI after lumbar spinal surgery. However, most of the studies were focused on the patient and procedure-related factors. Few studies reported the correlation between laboratory tests and postoperative SSI. METHODS: A retrospective study was carried out in a single institution. Patients who underwent posterior lumbar spinal surgery between January 2010 and August 2016 were included in this study. All patients' medical records were reviewed and patients with postoperative SSI were identified. Perioperative variables were included to determine the risk factors for SSI by univariate and multivariate regression analysis. RESULTS: A total of 2715 patients undergoing posterior lumbar spinal surgery were included in this study. Of these patients, 64 (2.4%) were detected with postoperative SSI, including 46 men and 18 women. Diabetes mellitus (P = 0.026), low preoperative serum level of calcium (P = 0.009), low preoperative and postoperative albumin (P = 0.025 and 0.035), high preoperative serum glucose (P = 0.029), multiple fusion segments (P < 0.001), increased surgical time and estimated blood loss (P = 0.023 and 0.005), decreased postoperative hemoglobin (P = 0.008), and prolonged drainage duration (P = 0.016) were found to be the independent risk factors for SSI. Multilevel fusion and a history of diabetes mellitus were the two strongest risk factors (odds ratio = 2.329 and 2.227) for SSI. CONCLUSION: Based on a large population analysis, previous reported risk factors for SSI were confirmed in this study while some new independent risk factors were identified significantly associated with SSI following lumbar spinal surgery, including preoperative low serum level of calcium, decreased preoperative and postoperative albumin, and decreased postoperative hemoglobin. LEVEL OF EVIDENCE: 4.

Incidence and risk factors for symptomatic spinal epidural haematoma following lumbar spinal surgery.

PURPOSE: Spinal epidural haematoma (SEH) is a common complication after lumbar spinal decompression surgery, and symptomatic SEH usually causes devastating neurological deficits. Although different risk factors for post-operative SEH have been reported, few studies focused on patients' laboratory tests. The purpose of this study was to analyze the incidence of symptomatic SEH following lumbar spinal surgery, as well as identify the risk factors for it. METHODS: Patients who underwent posterior lumbar spinal decompression surgery between January 2010 and August 2016 were included in this study and their medical records were retrospectively reviewed. Those who developed post-operative symptomatic SEH after the surgery were identified. The risk factors for SEH were analyzed by univariate and multivariate regression analysis. RESULTS: In total, 2715 patients were included in this study and 31 (1.14%) were identified with post-operative symptomatic SEH. Of these patients, 19 were males and 12 were females, with an average age of 59.39 ± 11.66 years. After multivariate logistic regression analysis, low serum calcium level (P = 0.025), blood type A (P = 0.04), increased estimated blood loss (P = 0.032), prolonged surgical duration (P = 0.018), and decreased post-operative globulin (P = 0.016) were identified as the independent risk factors for post-operative SEH following lumbar spinal surgery. Furthermore, prolonged surgical duration (odds ratio = 3.105) was the strongest risk factor for SEH. CONCLUSION: Based on a large population investigation, the incidence of symptomatic SEH following lumbar spinal decompression surgery was 1.14%. Blood type A, increased estimated blood loss, and prolonged surgical duration were identified as the independent risk factors for post-operative SEH while two new risk factors, including low serum calcium level and decreased post-operative globulin, were firstly identified in this study.

Unplanned Reoperation of Lumbar Spinal Surgery During the Primary Admission: A Multicenter Study Based on a Large Patient Population.

STUDY DESIGN: A retrospective study. OBJECTIVE: The purpose of this study was to identify the rates and reasons, and the risk factors for unplanned reoperation of lumbar spinal surgery during the primary admission in terms of a multicenter and a large patient population study. SUMMARY OF BACKGROUND DATA: Unplanned reoperation is suggested to be a useful quality indicator for spinal surgery. However, the rates of unplanned reoperation in patients underwent lumbar spinal surgery during the primary admission are not well established. METHODS: This study was performed to review all the patients who underwent lumbar spinal surgery at three institutions from January 2010 to April 2015. Patients with unplanned reoperations after primary surgery during the same admission were included in this study. The demographics, diagnosis, surgical procedure, and complications of patients were reviewed and statistical analysis was performed to investigate the incidences and risk factors of unplanned revision. RESULTS: A total of 3936 patients who underwent lumbar spinal surgery from three institutions were reviewed, and 82 (2.08%) required unplanned reoperation during the primary admission because of wound infection (0.94%), screw misplacement (0.53%), cerebrospinal fluid leakage (0.27%), wound hematoma (0.18%), and neurologic deficit (0.15%). For the diagnosis, patients with lumbar spinal spondylolisthesis had a much higher rate of reoperation (4.3%) than those of lumbar stenosis (2.3%), vertebral tumor (2.2%), vertebral fracture (1.2%), and disc herniation (1.1%) with a significant difference (P < 0.001). The revision rate was significantly higher in patients underwent posterior lumbar interbody fusion than those received transforaminal lumbar interbody fusion (P = 0.007). CONCLUSION: Unplanned reoperation rate of lumbar spinal surgery was 2.08% and the most common reasons for it were wound infection and screw misplacement. Patients with a diagnosis of lumbar spinal spondylolisthesis or who underwent posterior lumbar interbody fusion were more likely to required unplanned reoperation during the primary admission. LEVEL OF EVIDENCE: 4.