Differential electrophoretic mobility of synthetic DNA motifs and duplex DNA in various counter ions.

In this work, we analyzed the electrophoretic behavior of a double crossover (DX) DNA motif in various counter ions. The influence of the type and concentration of counter ions on electrophoretic behavior is different for the DX motif compared to a duplex of the same molecular weight. Higher concentrations of divalent ions Mg2+ and Ca2+ in the gel and running buffer reduce the electrophoretic migration of the DX motif. This effect is less pronounced in the monovalent ion Na+ while K+ ion did not have any significant effect on the electrophoretic behavior.

Risk Factors for Progression of Cervical Congenital Scoliosis and Associated Compensatory Curve Behavior.

Background: This study investigated risk factors for progression of deformity in pediatric congenital cervical scoliosis (CCS) and evaluated the correlation between congenital cervical curves and compensatory thoracic and lumbar curves. Methods: Medical records were retrospectively reviewed for 38 pediatric patients with CCS with a minimum 2-year follow-up. Curve progression was defined as >10° increase in cervical coronal curve angle between presentation and last follow-up. Results: A total of 38 patients (16 girls, 22 boys) with a mean age at presentation of 5.6 ± 4.1 years met the inclusion criteria. Sixteen patients (42%) had curve progression with a mean follow-up of 3.1 ± 3.0 years. At presentation, T1 slope was significantly larger among children with progressive deformities (p = 0.041). A total of 18 of the 38 patients with strictly cervical spine deformity were then selected for subanalysis to evaluate the progression of compensatory curves. Cervical major coronal curves were found to significantly correlate with lumbar major coronal curves (r = 0.409), C2 central sacral vertical line (CSVL) (r = 0.407), and C7-CSVL (r = 0.403) (p < 0.05). Thoracic major coronal curves did not significantly correlate with cervical major coronal curves (r = 0.218) (p > 0.05). Conclusion: In conclusion, 42% of osseous CCS curves progressed over time in the overall cohort, and high initial T1 slope was found to be most highly correlated with progression of cervical deformity. Cervical major coronal curves significantly correlated with lumbar curve magnitude but not with thoracic curve size in isolated CCS, possibly due to the increased flexibility of the lumbar spine which may allow greater compensatory balance and thus have a greater correlation with cervical curve magnitude and possibly progression.

The role of size in biostability of DNA tetrahedra.

The potential for using DNA nanostructures for drug delivery applications requires understanding and ideally tuning their biostability. Here we investigate how biological degradation varies with size of a DNA nanostructure. We designed DNA tetrahedra of three edge lengths ranging from 13 to 20 bp and analyzed nuclease resistance for two nucleases and biostability in fetal bovine serum. We found that DNase I had similar digestion rates across sizes but appeared to incompletely digest the smallest tetrahedron, while T5 exonuclease was notably slower to digest the largest tetrahedron. In fetal bovine serum, the 20 bp tetrahedron was degraded four times faster than the 13 bp. These results show that DNA nanostructure size can influence nuclease degradation, but suggest a complex relationship that is nuclease specific.

The role of size in biostability of DNA tetrahedra.

The potential for using DNA nanostructures for drug delivery applications requires understanding and ideally tuning their biostability. Here we investigate how biological degradation varies with size of a DNA nanostructure. We designed DNA tetrahedra of three edge lengths ranging from 13 to 20 bp and analyzed nuclease resistance for two nucleases and biostability in fetal bovine serum. We found that DNase I had similar digestion rates across sizes but appeared to incompletely digest the smallest tetrahedron, while T5 exonuclease was notably slower to digest the largest tetrahedron. In fetal bovine serum, the 20 bp tetrahedron was degraded ~four times faster than the 13 bp. These results show that DNA nanostructure size can influence nuclease degradation, but suggest a complex relationship that is nuclease specific.

Gender and Racial Bias in Letters of Recommendation for Orthopedic Surgery Residency Positions.

OBJECTIVE: The primary purpose of this study was to retrospectively analyze letters of recommendation written for medical students applying to orthopedic residency for implicit race and gender bias. The secondary purpose was to determine if the presence of bias was influenced by the gender of the letter writer. DESIGN: This was a retrospective institutional review board (IRB) approved study. All letters of recommendation received in the years 2016 to 2018 were deidentified and analyzed using the Linguistics Inquiry and Word Count (LIWC) 2015 software. Independent variables in our analysis were applicant gender and applicant race. Dependent study variables included the summary and characteristic variables of a letter of recommendation, which are word count, analytic, clout, authenticity, tone, and positive and negative emotion word categories. Separate analyses were completed by gender of the letter writer as well. SETTING: Institution: Temple University Hospital, Philadelphia, Pennsylvania. PARTICIPANTS: Medical students applying to Temple University Hospital Orthopaedic Surgery Program from 2016 to 2018. A total of 2113 applicants were included in the study. RESULTS: Female, Asian and underrepresented minority applicants' letters were more likely to have a higher word count. In our subset analysis by gender of letter writer, when the letter writer was male, Asian applicants' letters were more likely to convey analytical thinking and authenticity. When the letter writer was male, male applicants scored higher for authenticity. Letters written by female attendings demonstrated no significant difference for male or female applicants in terms of composite variables or word categories. CONCLUSIONS: Our study shows that letters of recommendation for orthopedic surgery residency positions are likely to contain some degree of bias. Further studies are required to fully characterize the degree and magnitude of bias in letters of recommendation and whether the findings of our study are significant enough to contribute to the difference in socioeconomic demographics between orthopedic residents and society at large.

Purification of Self-Assembled DNA Tetrahedra Using Gel Electrophoresis.

DNA nanostructures have found applications in a variety of fields such as biosensing, drug delivery, cellular imaging, and computation. Several of these applications require purification of the DNA nanostructures once they are assembled. Gel electrophoresis-based purification of DNA nanostructures is one of the methods used for this purpose. Here, we describe a step-by-step protocol for a gel-based method to purify self-assembled DNA tetrahedra. With further optimization, this method could also be adapted for other DNA nanostructures. © 2022 Wiley Periodicals LLC. Basic Protocol: Purification of self-assembled DNA tetrahedra.

Does Interbody Cage Lordosis and Position Affect Radiographic Outcomes After Single-level Transforaminal Lumbar Interbody Fusion?

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: The objective of this study was to determine if the degree of interbody cage lordosis and cage positioning are associated with changes in postoperative sagittal alignment after single-level transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: Ideal sagittal alignment and lumbopelvic alignment have been shown to correlate with postoperative clinical outcomes. TLIF is one technique that may improve these parameters, but whether the amount of cage lordosis improves either segmental or lumbar lordosis (LL) is unknown. METHODS: A retrospective review was performed on patients who underwent single-level TLIF with either a 5-degree or a 12-degree lordotic cage. LL, segmental lordosis (SL), disk height, center point ratio, cage position, and cage subsidence were evaluated. Correlation between center point ratio and change in lordosis was assessed using the Spearman correlation coefficient. Secondary analysis included multiple linear regression to determine independent predictors of change in SL. RESULTS: A total of 126 patients were included in the final analysis, with 51 patients receiving a 5-degree cage and 75 patients receiving a 12-degree cage. There were no differences in the postoperative minus preoperative LL (∆LL) (12-degree cage: -1.66 degrees vs. 5-degree cage: -2.88 degrees, P =0.528) or ∆SL (12-degree cage: -0.79 degrees vs. 5-degree cage: -1.68 degrees, P =0.513) at 1-month follow-up. Furthermore, no differences were found in ∆LL (12-degree cage: 2.40 degrees vs. 5-degree cage: 1.00 degrees, P =0.497) or ∆SL (12-degree cage: 1.24 degrees vs. 5-degree cage: 0.35 degrees, P =0.541) at final follow-up. Regression analysis failed to show demographic factors, cage positioning, or cage lordosis to be independent predictors of change in SL. No difference in subsidence was found between groups (12-degree cage: 25.5% vs. 5-degree cage: 32%, P =0.431). CONCLUSION: Lordotic cage angle and cage positioning were not associated with perioperative changes in LL, SL, or cage subsidence after single-level TLIF. LEVEL OF EVIDENCE: Level III.

Do drains help reduce the risk of complications after thoracoplasties in posterior spinal fusions for adolescent idiopathic scoliosis?

PURPOSE: In adolescent idiopathic scoliosis (AIS), the rib prominence is a major cosmetic concern which can be improved using thoracoplasties. We sought to determine if the use of deep drains helps minimize the development of pleural effusions after thoracoplasties. METHODS: Retrospective study of 45 patients with AIS undergoing posterior spinal fusion (PSF) and thoracoplasties. RESULTS: Thirty six out of 45 patients (80.0%) required placement of a deep surgical drain, and 16 out of 45 (35.6%) developed pleural effusions after PSF with concomitant thoracoplasty. Of the 16 patients who developed pleural effusion, 12 of 36 (33.3%) required a placement of a deep drain (p > 0.05). Of the total 45 patients in this cohort, 3 patients (6.7%) required chest tubes, and 4 patients (8.9%) developed surgical site infections (SSIs). We found that deep drains were associated with a lower incidence of SSI (2.8% vs 33.3%; p = 0.021). Patients who had a pleural effusion had longer ICU stays (p = 0.037) and longer requirements of nasal oxygen (p = 0.025). DISCUSSION: The presence of a pleural effusion in patients with AIS undergoing PSF with thoracoplasty was associated with longer oxygen requirements and length of hospital ICU admission. Thirty six percent of patients with thoracoplasties developed pleural effusions, but deep subfascial drains did not significantly decrease the incidence of pleural effusions.

Risk Stratification Algorithm for Orthopedic Trauma Patients at Risk for Fat Embolism Syndrome.

BACKGROUND: Fat embolism syndrome (FES) is commonly reported in the setting of long bone and pelvic fractures, but the etiology and pathogenesis are unclear. The aim of this study was to identify clinical characteristics and laboratory findings that may place orthopedic trauma patients at a higher risk of developing FES. METHODS: Electronic medical records were reviewed of all patients aged 18-89 years from 2015 to 2020 with a mention of FES in the patient chart who met Gurd and Wilson's criteria for diagnosis after experiencing orthopedic trauma. A 3:1 matched pair analysis was performed between FES patients and those with similar age, gender, and FES-associated fracture (femur, tibia, humerus, or pelvis fracture). RESULTS: 18 patients with FES who met inclusion criteria were identified. Hypomagnesemia (OR = 7.43), hyperphosphatemia (OR = 6.24), hypoalbuminemia (OR = 3.78), blunt traumatic mechanism of injury (OR = 7.16) and a greater number of bones fractured (Avg/SD = 2.89/1.53) were seen more often in FES patients (all p-values < 0.05). CONCLUSION: Findings of this study suggest that patients with hypomagnesemia, hyperphosphatemia, hypoalbuminemia, a blunt trauma mechanism of injury, and an increased number of bones fractured are at increased risk for the development of FES. This may be related to their roles in physiologic oncotic pressure and inflammatory response, and thus further investigation of these variables is necessary for the evaluation of FES prevention. LEVEL OF EVIDENCE: Level 3.

Early and late hospital readmissions in adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective review of a prospectively collected multicenter database. OBJECTIVES: To identify risk factors for early and late readmission of surgically treated patients with adolescent idiopathic scoliosis (AIS). Specific risk factors associated with readmission in patients with AIS remain poorly understood. METHODS: Patients with AIS who were operatively treated from 19 centers specializing in the treatment of pediatric spinal deformity were studied. Data from a minimum 2 years of clinical follow-up and any readmission were available for analysis. Characteristics of patients with no readmission, early readmission (< 90 days), and late readmission (> 90 days) were evaluated. Both univariate and multivariate analyses of risk factors for readmission were performed. RESULTS: 2049 patients were included in our cohort, with 1.6% requiring early readmission and 3.3% late readmission. In the multivariate analysis, greater preoperative coronal imbalance was associated with early readmission. Longer operative time was associated with late readmission. Finally, greater preoperative pain (SRS-22 pain scale) was associated with both early and late readmission. GI complications accounted for a higher proportion of early readmissions than previously reported in the literature. CONCLUSIONS: Preoperative counseling of patients with higher levels of pain and coronal imbalance and the implementation of a thorough postoperative bowel regimen may help optimize patient outcomes. LEVEL OF EVIDENCE: 3.

Prevalence of Venous Thromboembolism Following Acute Spinal Cord Injury in an Urban Inner City Hospital.

BACKGROUND: Venous thromboembolism (VTE) is known to occur at high rates in patients who suffer spinal cord injury (SCI). Large population studies in the United States have shown a prevalence of approximately 4-5%, with some studies suggesting higher prevalence. While the specific mechanism behind increased VTE incidence in the SCI population is unknown, it is likely tied to immobility and functional decline. Previous studies have also linked social determinants of health to higher VTE prevalence in certain populations. The purpose of this study is to determine the prevalence of VTE after acute SCI in the inner urban city population and to identify factors that place patients at increased VTE risk. METHODS: Patients who suffered SCI between 2014 and 2019 were identified from one inner city urban hospital. A retrospective chart review was completed to record the development of VTE after SCI. Medical comorbidities, type of thromboprophylaxis used, patient demographics, injury characteristics, and postinjury sequelae were compared between individuals who did and did not develop VTE. RESULTS: A total of 148 patients were included. These patients were from a low socioeconomic demographic when compared with the larger US population. Average household income based on zip code data for included patients was $56 647, $30 315 below the national average. The prevalence of VTE in this patient population was 19.59%. Weight, deep vein thrombosis history, chemoprophylaxis use, mobility impairment postinjury, neurologic level of SCI, malignancy history, and history of smokeless tobacco were associated with VTE (all P < .05). Low molecular weight heparin (LMWH) use was associated with fewer occurrences of VTE (P < .001). CONCLUSION: Patients from our urban inner city hospital have a higher VTE prevalence after SCI than shown in previous US-based studies. These patients may be at increased risk due to increased numbers of medical comorbidities, social factors, or undiagnosed medical conditions. Thromboprophylaxis with LMWH appears to lower the risk of VTE after SCI. LEVEL OF EVIDENCE: 3. CLINICAL RELEVANCE: Patients with the previously mentioned risk factors are at increased risk for VTE development during their acute recovery process. These patients should have a much lower screening threshold for VTE evaluation and likely would benefit from more routine screening to prevent complications related to VTE development or progression. Furthermore, these patients should, when medically appropriate, be treated with low molecular weight heparin for VTE prophylaxis as previously recommended by the Consortium for Spinal Cord Medicine.