Secondary Coordination Sphere Influences the Formation of Fe(III)-O or Fe(III)-OH in Nitrite Reduction: A Synthetic and Computational Study.

The reduction of nitrite (NO2-) to generate nitric oxide (NO) is a significant area of research due to their roles in the global nitrogen cycle. Here, we describe various modifications of the tris(5-cyclohexyliminopyrrol-2-ylmethyl)amine H3[N(piR)3] ligand where the steric bulk and acidity of the secondary coordination sphere were explored in the non-heme iron system for nitrite reduction. The cyclohexyl and 2,4,6-trimethylphenyl variants of the ligand were used to probe the mechanism of nitrite reduction. While previously stoichiometric addition of nitrite to the iron(II)-species generated an iron(III)-oxo complex, changing the secondary coordination sphere to mesityl resulted in an iron(III)-hydroxo complex. Subsequent addition of an electron and two protons led to the release of water and regeneration of the starting iron(II) catalyst. This sequence mirrored the proposed mechanism of nitrite reduction in biological systems, where the distal histidine residue shuttles protons to the active site. Computational studies aimed at interrogating the dissimilar behavior of the cyclohexyl and mesityl ligand systems resulting in Fe(III)-oxo and Fe(III)-hydroxo complexes, respectively, shed light on the key role of H-bonds involving the secondary coordination sphere in the relative stability of these species.

Characterization of Terminal Iron(III)-Oxo and Iron(III)-Hydroxo Complexes Derived from O2 Activation.

O2 activation at nonheme iron centers is a common motif in biological systems. While synthetic models have provided numerous insights into the reactivity of high-valent iron-oxo complexes related to biological processes, the majority of these complexes are synthesized using alternative oxidants. This report describes O2 activation by an iron(II)-triflate complex of the imino-functionalized tris(pyrrol-2-ylmethyl)amine ligand framework, H3[N(piCy)3]. Initial reaction conditions result in the formation of a mixture of oxidation products including terminal iron(III)-oxo and iron(III)-hydroxo complexes. The relevance of these species to the O2 activation process is demonstrated through reactivity studies and electrochemical analysis of the iron(III)-oxo complex.

Bipolar Sealer Devices Used in Posterior Spinal Fusion for Neuromuscular Scoliosis Reduce Blood Loss and Transfusion Requirements.

BACKGROUND: Reducing perioperative blood loss and the need for transfusions in patients undergoing spinal surgery is especially important for those with neuromuscular disorders. These patients require extensive spino-pelvic exposure and are often medically fragile. We have used Amicar to decrease blood loss since 2001. As an effort to further reduce blood loss and transfusions, we use a bipolar sealer device (Aquamantys) as an adjunct to electrocautery. We present the results of our first 64 neuromuscular patients to show the efficacy of the device. METHODS: Using a prospectively maintained database we reviewed the operative time, estimated perioperative blood loss, cell saver use, and intraoperative and postoperative transfusion rate in patients who underwent posterior spinal fusion for neuromuscular scoliosis. Sixty-four patients were identified who fit these criteria since the use of the bipolar sealer device was instituted.We compared these patients with a control group of the preceding 65 patients in whom this device was not used for hemostasis. All patients, including those in the study group, received Amicar (infusion of 100 mg/kg over 15 to 20 min, then 10 mg/kg/h throughout the remainder of the procedure). The surgical technique did not differ between the 2 groups. RESULTS: Baseline characteristics between the 2 groups were similar except for the number of patients having an all-screw construct which was larger in the investigational group (25% vs. 8%, P=0.03). There were no significant differences in operative time or duration of hospital stay. Intraoperative blood loss was lower in the study group (741 mL) as compared with the control group (1052 mL, P=0.003). Total perioperative blood loss, however, showed no significant difference. Thirty-five (55%) patients in the study group and 50 (77%) patients in the control group required additional intraoperative or postoperative transfusions (P=0.01). The number of packed red cell units transfused per patient was 0.81 in the study group and 1.57 in the control group (P=0.001). Although the intraoperative cell saver transfusion was same, the total blood volume transfused, which includes cell saver and any other transfusions, was significantly lower in the study group, 425 mL versus 671 mL (P=0.002). CONCLUSIONS: Use of a bipolar sealer device in posterior spinal fusion for neuromuscular scoliosis significantly reduced intraoperative blood loss and transfusion rate when compared with a control group in this retrospective review. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Tuning the Fe(II/III) Redox Potential in Nonheme Fe(II)-Hydroxo Complexes through Primary and Secondary Coordination Sphere Modifications.

The derivatization of the imino-functionalized tris(pyrrolylmethyl)amine ligand framework, N(XpiR)3 (XLR; X = H, Br; R = cyclohexyl (Cy), phenyl (Ph), 2,6- diisopropylphenyl (DIPP)), is reported. Modular ligand synthesis allows for facile modification of both the primary and secondary coordination sphere electronics. The iron(II)-hydroxo complexes, N(XpiR)(XafaR)2Fe(II)OH (XLRFeIIOH), are synthesized to establish the impact of the ligand modifications on the complexes' electronic properties, including their chemical and electrochemical oxidation. Cyclic voltammetry demonstrates that the Fe(II/III) redox couple spans a 400 mV range across the series. The origin of the shifted potential is explained based on spectroscopic, structural, and theoretical analyses of the iron(II) and iron(III) compounds.

Increased and decreased pelvic incidence, sagittal facet joint orientations are associated with lumbar spine osteoarthritis in a large cadaveric collection.

PURPOSE: Degenerative joint disease of the lumbar spine is a pervasive problem in healthcare; however, its aetiology and risk factors remain poorly defined. There have been recent attempts to correlate the anatomic parameters of facet angle and pelvic incidence with spine osteoarthritis, although data remains limited. The purpose of this experiment was to determine how age, gender, race, facet angle, tropism, and pelvic incidence correlate to facet joint osteoarthritis in the lumbar spine. METHODS: A total of 576 cadaveric lumbar spines were obtained. Using validated techniques, facet angle, tropism, and pelvic incidence were measured. Osteoarthritis of the lumbar spines was graded from 0-4 at each level. Correlations between osteoarthritis and age, gender, facet angle, tropism, and pelvic incidence were evaluated with regression analysis. RESULTS: Facet angle became more coronally oriented, and facet tropism increased from L1-L2 to L5-S1. Arthritis was highest at the L4-L5 joint (2.2 ± 1.1), compared to the L5-S1 (2.1 ± 1.1), L3-L4 (1.9 ± 1.1), L2-L3 (1.5 ± 1.0) and L1-L2 (1.0 ± 1.0) joints (p < 0.001). Age was the strongest predictor of arthritis at all levels (standardized betas 0.342 through 0.494, p < 0.001). Correlations between gender, race and osteoarthritis were not significant at any level. A decreased facet angle was predictive of increased arthritis at each joint level (standardized betas -0.091 through -0.153, p < 0.05 for all). Tropism was a predictor of increased arthritis at caudal levels. Pelvic incidence was a predictor of increased arthritis at L3-L4 (standardized beta 0.080, p = 0.02), L4-L5 (standardized beta 0.081,p = 0.02), and L5-S1 (standardized beta 0.100, p = 0.01). CONCLUSIONS: Facet arthritis was correlated with a more sagittal orientation of the facet joints, increased tropism, and perturbations of pelvic incidence.

Uroepithelial Thickening on Sonography Improves Detection of Vesicoureteral Reflux in Children with First Febrile Urinary Tract Infection.

PURPOSE: The 2011 American Academy of Pediatrics clinical practice guideline for childhood febrile urinary tract infection recommends voiding cystourethrography if renal and bladder ultrasound reveals hydronephrosis, scarring or "other findings" that suggest high grade vesicoureteral reflux. We sought to determine if the finding of uroepithelial thickening indicates greater risk of high grade vesicoureteral reflux and whether uroepithelial thickening improves the screening value of renal and bladder ultrasound. MATERIALS AND METHODS: We retrospectively analyzed renal and bladder ultrasound and voiding cystourethrogram findings in children 2 to 24 months old with first febrile urinary tract infection during an 11-year period. Patients with uroepithelial thickening were compared to an age and gender matched sample without uroepithelial thickening. Logistic regression was used to identify factors associated with high grade vesicoureteral reflux. Test characteristics of renal and bladder ultrasound for high grade reflux were compared based on different criteria to define an abnormal renal and bladder ultrasound. RESULTS: Of 226 patients 143 (63%) had vesicoureteral reflux, of whom 37 (26%) had high grade reflux. On multivariable analysis uroepithelial thickening was a significant independent predictor of high grade vesicoureteral reflux (OR 5.41, 95% CI 1.74-16.79, p = 0.004). When hydronephrosis and hydroureter were considered the only abnormal renal and bladder ultrasound findings warranting voiding cystourethrography, sensitivity of renal and bladder ultrasound for high grade reflux was 84%, and 6 children with high grade and 82 with low grade reflux would have been missed. When uroepithelial thickening was also considered an abnormal finding, the sensitivity increased to 97%, and only 1 child with high grade and 57 with low grade reflux would have been missed. CONCLUSIONS: Uroepithelial thickening is associated with an increased risk of high grade vesicoureteral reflux and is an abnormal finding warranting voiding cystourethrography. Sensitivity of renal and bladder ultrasound as a screening test for high grade vesicoureteral reflux is markedly improved when uroepithelial thickening is considered.

Completely intracorporeal robotic renal autotransplantation.

PURPOSE: We describe a technique of complete intracorporeal renal autotransplantation with donor nephrectomy and transplantation performed in a minimally invasive fashion without extracting the kidney. MATERIALS AND METHODS: We developed this technique of a completely intracorporeal robotic renal autotransplantation and determined the feasibility of this novel procedure. This includes a method of intracorporeal transarterial hypothermic renal perfusion using a perfusion catheter through a laparoscopic port. The procedure was successfully applied in a 56-year-old man with extensive left ureteral loss after failed ureteroscopy for ureterolithiasis. RESULTS: Robotic donor nephrectomy was performed with a warm ischemia time of 2.3 minutes. Subsequently cold ischemia was achieved by intracorporeal hypothermic renal perfusion for 95.5 minutes. Vascular anastomoses and ureteroureterostomy in the ipsilateral pelvis were completed after donor nephrectomy with a total overall surgeon console time of 334 minutes. Venous and arterial anastomosis times were 17.3 and 21.3 minutes, respectively. Estimated blood loss was less than 50 ml. There were no complications and the patient was discharged home on postoperative day 1 after normal Doppler transplant renal ultrasound. Postoperative renal scan at 6 weeks, intravenous urogram at 8 weeks and computerized tomography urography at 5 months revealed normal function and successful ureteral reconstruction. CONCLUSIONS: We report the feasibility of a technique of a completely intracorporeal robotic renal autotransplantation. This operation may be considered in select patients in the hands of experienced robotic surgeons. However, further refinement is required as this novel procedure is cautiously reproduced and adopted by others.

Tuning reactivity and electronic properties through ligand reorganization within a cerium heterobimetallic framework.

Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational syntheses of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

Correlation of slipped capital femoral epiphysis with disk degeneration.

SUMMARY OF BACKGROUND DATA: Spinal osteoarthritis is greater in patients with known hip pathology secondary to alterations in spinopelvic geometry. To our knowledge, no study has investigated the long-term impact of slipped capital femoral epiphysis (SCFE) on the spine. OBJECTIVE: To evaluate the relationship between SCFE and the presence of degenerative disk disease and facet arthrosis. STUDY DESIGN: An anatomic study of disk degeneration in cadaveric lumbar spines with SCFE. METHODS: An observational study was performed on 25 cadaveric specimens with SCFE and 647 controls that were identified out of 3100 total cadaveric specimens in an osteological collection. The specimens were evaluated for disk degeneration and facet arthrosis at L1/2 to L5/S1 using the classification of Eubanks and colleagues. Linear regression analyses were then used to determine the relationship between SCFE and lumbar disk and facet degeneration at each level, correcting for confounding factors such as age, sex, and race. RESULTS: Linear regression demonstrated a significant association (P<0.01) that was found between SCFE and degenerative disk disease at all levels from L1/2 to L5/S1. In addition, a significant association (P<0.01) was found between SCFE and facet arthrosis at all levels from L1/2 to L5/S1. CONCLUSIONS: The findings of this study show a relationship between SCFE and lumbar disk degeneration and facet arthrosis. This relationship may prove useful in predicting the course of spinal osteoarthritis in patients with SCFE.

Bipolar sealer device reduces blood loss and transfusion requirements in posterior spinal fusion for adolescent idiopathic scoliosis.

BACKGROUND: Reducing perioperative blood loss and transfusion requirements is important in the operative treatment of idiopathic scoliosis. This can be achieved with special frames, cell saver systems, pharmacologic aspects, and other techniques. Recently there has been interest in bipolar sealer devices as an adjunct to traditional monopolar electrocautery. However, there is limited information on this device in pediatric spinal deformity surgery. We reviewed our experience with this device in a setting of a standard institutional operative carepath. METHODS: Perioperative blood loss and transfusion requirements of 50 consecutive patients with adolescent idiopathic scoliosis undergoing a posterior spinal fusion and segmental spinal instrumentation and who had a bipolar sealer device used during their surgery was compared with a control group of the 50 preceding consecutive patients who did not. Anesthesia, surgical technique, use of intraoperative epsilon aminocaproic acid (Amicar), postoperative protocol, and indications for transfusions (hemoglobin≤7.0 g/dL) were identical in both groups. RESULTS: The preoperative demographics for the patients in both groups were statistically the same. The bipolar sealer group demonstrated a significant reduction in intraoperative estimated blood loss, total perioperative blood loss, volume of blood products transfused, and overall transfusion rate when compared with the control group. When subgroups consisting of only hybrid or all-pedicle screw constructs were considered individually, these findings remained consistent. There were no complications associated with the use of this device. CONCLUSIONS: Using the bipolar sealer device is a significant adjunct in decreasing perioperative blood loss and transfusion requirements in patients undergoing surgery for adolescent idiopathic scoliosis. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Aggressive thoracic vertebral hemangioma: case report and literature review.

INTRODUCTION: Vertebral hemangiomas are common and typically benign vascular lesions, with a prevalence of 10-12% in the general population and 2-3% in all spine tumors. A small subset of vertebral hemangiomas can be categorized as "aggressive" if they exhibit extraosseous expansion that compress the spinal cord, causing pain and various neurologic symptoms. This report details a case of aggressive thoracic hemangioma resulting in worsening pain and paraplegia to draw attention to this rare condition, including identification and treatment. CASE PRESENTATION: In this case, we present a 39 year-old female with a history of progressively worsening pain and paraplegia caused by compression of the spinal cord from an aggressive thoracic vertebral hemangioma. Clinical presentation, imaging, and biopsies, confirmed the diagnosis. A combined surgical and endovascular treatment strategy was implemented, and the patient's symptoms improved. DISCUSSION: Aggressive vertebral hemangioma is a rare condition that may cause symptoms that diminishes the quality of life, including pain and various neurological symptoms. Given the low number of such cases, and significant impact on lifestyle, it is beneficial to identify cases of aggressive thoracic hemangiomas to ensure timely and accurate diagnosis and help development of treatment guidelines. This case highlights the importance of identifying and diagnosing this rare but serious disease.

Spine centers of excellence: a systematic review and single-institution description of a spine center of excellence.

Background: Centers of excellence (COEs) are interdisciplinary healthcare organizations created with the goal of improving health/economic outcomes in medical treatment for both individuals and health systems, compared to traditionally structured counterparts. Multiple studies have highlighted both societal/individual burdens associated with back pain, underscoring the importance of identifying new avenues for improving both cost/clinical outcomes for this patient population. Here, we utilize available literature to better characterize the features of a spine COE at a tertiary care center and determine the impact of COEs on patient satisfaction and outcomes. Methods: A systematic review describing spine COEs was performed. PubMed, OVID, Cochrane, Web of Science, and Scopus were utilized for electronic literature search. Data including institution, department, pathologies treated, patient satisfaction scores, patient outcomes, and descriptions of the COE, were extracted and analyzed by two reviewers per full-text article. Inclusion criteria consisted of literature describing the organization, purpose, or outcomes of a spine COE, all publication types (except technical/operative report), adult or pediatric patients, publication from inception through September 2021. Exclusion criteria consisted of articles that do not discuss spinal COEs, technical/operative reports, studies unavailable in English language, unavailable full text, or non-human subjects. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of the included studies. Results: Five hundred and sixty-seven unique publications were obtained from the literature search. Of these articles, 20 were included and 547 were excluded based on inclusion and exclusion criteria. Following full-text review of the 20 publications, 6 contained pertinent data. Quantitative data comparing COE versus non-COE was contradictory in comparing complication rates and episodic costs. Qualitative data included descriptions of spine COE features and cited improved patient care, technical advancements, and individualized care paths as positive aspects of the COE model. Mean risk of bias assessment was 3.67. Discussion: There is little evidence regarding if spine COEs provide an advantage over traditionally organized facilities. The current number and heterogeneity of publications, and lack of standardized metrics used to define a spinal COE are limiting factors. Spinal COE may offer higher value care, reduced complication rates and advancements in knowledge and technical skill.

Three siblings with Chance fractures: the importance of 3-point restraints.

Pediatric Chance fractures are uncommon injuries. They are the result of a flexion-distraction force applied to the spine, and most commonly occur from motor vehicle accidents in which passengers are wearing lap seat belts as opposed to 3-point restraints with a chest strap. Neurologic injuries are rarely associated with Chance fractures in children, but accompanying intraabdominal injuries are often found and carry a potential for significant morbidity. We present 3 siblings in a minivan who were involved in a high-speed motor vehicle accident and as a result of wearing their 3-point restraints improperly, suffered Chance fractures. None had neurologic dysfunction, but 2 had serious intra-abdominal injuries requiring surgical repair. All 3 Chance fractures were treated with cast immobilization. This case report shows the importance of wearing 3-point restraints properly while traveling in a motor vehicle.

Development of a Transformation Method for Metschnikowia borealis and other CUG-Serine Yeasts.

Yeasts belonging to the Metschnikowia genus are particularly interesting for the unusual formation of only two needle-shaped ascospores during their mating cycle. Presently, the meiotic process that can lead to only two spores from a diploid zygote is poorly understood. The expression of fluorescent nuclear proteins should allow the meiotic process to be visualized in vivo; however, no large-spored species of Metschnikowia has ever been transformed. Accordingly, we aimed to develop a transformation method for Metschnikowiaborealis, a particularly large-spored species of Metschnikowia, with the goal of enabling the genetic manipulations required to study biological processes in detail. Genetic analyses confirmed that M. borealis, and many other Metschnikowia species, are CUG-Ser yeasts. Codon-optimized selectable markers lacking CUG codons were used to successfully transform M. borealis by electroporation and lithium acetate, and transformants appeared to be the result of random integration. Mating experiments confirmed that transformed-strains were capable of generating large asci and undergoing recombination. Finally, random integration was used to transform an additional 21 yeast strains, and all attempts successfully generated transformants. The results provide a simple method to transform many yeasts from an array of different clades and can be used to study or develop many species for various applications.

Differences in Cross-Sectional Intervertebral Foraminal Area From C3 to C7.

STUDY DESIGN: Anatomical comparative study. OBJECTIVES: Few studies have evaluated foraminal areas in the cervical spine without degenerative changes. The purpose of this study was to determine and compare the mean cross-sectional foraminal areas between the C3/4, C4/5, C5/6, and C6/7 levels while also analyzing specimens for differences between sexes and races. METHODS: We performed an anatomic study of the intervertebral foramen at 4 levels (C3/4, C4/5, C5/6, C6/7) in 100 skeletally mature osseous specimens. Specimens were selected to obtain equal number of African American and Caucasian males and females (n = 25/group) aged 20 to 40 years at time of death. Foramina were photographed bilaterally with and without a silicone rubber disc. The maximal vertical height and mid-sagittal width of each foramen were digitally measured and the areas were calculated using an ellipse as a model. RESULTS: The average age at death for all specimens was 30 ± 6 years. The mean cross-sectional area of the C4/5 foramen was significantly smaller compared with the C5/6 (P < .001). C5/6 was significantly narrower than C6/7 (P < .001) foramen with and without disc augmentation. C3/4 was not significantly different from more caudal levels. There was no difference between male and female specimens, while African Americans had smaller foraminal sizes than Caucasians. CONCLUSIONS: This study provides the largest anatomical reference of the cervical intervertebral foramen. In a mature spine without facet joint hypertrophy or osteophytic changes, the C4/5 foramen was narrower than C5/6, which was narrower than C6/7. Understanding the relative foraminal areas in the nonpathological cervical spine is crucial to understanding degenerative changes as well as the anatomical changes in pathologies that affect the intervertebral foramen.

Relationship Between Foraminal Area and Degenerative Changes in the Lower Cervical Spine With Implications for C5 Nerve Root Palsy.

Preoperative foraminal stenosis at C4/5 is a predisposing risk factor for C5 nerve root palsy in elderly patients. However, the area of the C4/5 intervertebral foramen and its relationship to the extent of arthrosis and lower foraminal areas (C5/6 and C6/7) are unknown. The authors sought to compare the areas of the cervical intervertebral foramen at the C4/5, C5/6, and C6/7 levels, noting any differences across race or sex and the relationship between foraminal area and arthrosis grade. A total of 600 cervical foramina from an osseous collection were examined. One hundred specimens between the ages of 60 and 80 years were selected, 50 from each sex and race (white and African American). Foramina were photographed bilaterally at C4/5, C5/6, and C6/7. Vertical height and mid-sagittal width were digitally measured. The degree of arthrosis within each intervertebral foramen was graded by 2 of the authors independently using the Kellgren-Lawrence grading system. Average age of death for specimens was 69.3±5.9 years. The mean foraminal areas at C4/5 (P=.001) and C5/6 (P<.001) were significantly smaller than at C6/7. Whites had larger foraminal areas than African Americans at C4/5 (P=.05) and C6/7 (P=.01). Arthrosis grade was found to make a significant contribution to foraminal area at C4/5 (standardized beta=-0.267; P<.001), but not at C5/6 or C6/7. A higher grade of arthrosis was associated with a narrower intervertebral foramen at the C4/5 level in osseous specimens from elderly individuals. [Orthopedics. 2018; 41(4):e506-e510.].

Recurrent anterior cervical wound abscesses following cervical corpectomy and fusion surgery from an odontogenic source mimicking an esophageal perforation: a case report.

CONTEXT: Infection is an uncommon complication of anterior cervical spine surgery. Most deep postoperative infections are thought to be related to occult esophageal perforation. Direct inoculation from the oropharynx has not been previously reported in the literature. PURPOSE: The purpose of this study is to report a case of recurrent infection after anterior cervical decompression and fusion suspected to have resulted from direct communication between the oropharynx and deep neck space. STUDY DESIGN: This study is a case report. METHODS: This study included longitudinal clinical and radiological follow-up. RESULTS: A 48-year-old woman who underwent anterior cervical corpectomy and fusion from C3 to C6 and posterior spinal fusion from C3 to C7 presented at 2 weeks and 5 months postoperatively with a deep neck space infection. She underwent surgical debridement each time. Workup of the second infection found a subtle cortical breach in the mandible at the site of prior invasive dental work. CONCLUSIONS: This case describes the workup and management of a patient who presented with recurrent deep neck space infection following anterior cervical spine surgery. This is the first report of a postoperative infection related to direct communication between the oropharynx and deep neck space via a cortical breach of the mandible.

Increased Pelvic Incidence is Associated With a More Coronal Facet Orientation in the Lower Lumbar Spine: A Cadaveric Study of 599 Lumbar Spines.

STUDY DESIGN: An anatomic study of facet angle orientation and morphology of the lumbar spine was performed. OBJECTIVE: The aim of this study was to determine how age, gender, race, and pelvic incidence (PI) correlate with facet orientation in the lumbar spine. SUMMARY OF BACKGROUND DATA: Lumbar facet orientation has important implications in the development of numerous pathologies of the spine, including arthritis, spondylolisthesis, and adult spinal deformity. Preliminary reports have suggested that sagittal balance of the spine may contribute to facet joint orientation. We therefore designed an anatomic study to investigate the relationship between PI and facet orientation, within the context of age, gender, and race. METHODS: Five hundred ninety-nine cadaveric lumbar spines were obtained from the Hamann-Todd osteological collection. It was determined that facet angle was most reliably assessed by measuring the angle between the superior articular facet and the spinous process. Facet angles were measured bilaterally at each level from T12-L1 through L5-S1 in every specimen. Multivariate regression analysis was used to determine independent predictors of facet angle at each level. RESULTS: Facet angle increased rostrally to caudally, from 22.6 ±â€Š8.3° at T12-L1 to 49.1 ±â€Š12.4° at L5-S1. Cadaver age was an independent predictor of a more sagittal facet angle at lower spinal levels. Caucasian race was an independent predictor of increasing facet angle. Increased PI had no effect on facet angle at T12-L1, L1-L2, L2-L3, or L3-L4, although was a significant predictor of more coronally oriented facet joints at L4-L5 (standardized beta 0.096, P = 0.009) and L5-S1 (standardized beta 0.079, P = 0.032). CONCLUSION: The results of this study provide important data regarding differences in facet angle that exists between individuals. Moreover, the results of this study suggest that facet joints do possess the ability to remodel over time, perhaps in response to perturbations of sagittal balance, osteophyte formation, or other yet to be determined factors. LEVEL OF EVIDENCE: N/A.

A bioinspired iron catalyst for nitrate and perchlorate reduction.

Nitrate and perchlorate have considerable use in technology, synthetic materials, and agriculture; as a result, they have become pervasive water pollutants. Industrial strategies to chemically reduce these oxyanions often require the use of harsh conditions, but microorganisms can efficiently reduce them enzymatically. We developed an iron catalyst inspired by the active sites of nitrate reductase and (per)chlorate reductase enzymes. The catalyst features a secondary coordination sphere that aids in oxyanion deoxygenation. Upon reduction of the oxyanions, an iron(III)-oxo is formed, which in the presence of protons and electrons regenerates the catalyst and releases water.