Effect of Surgeon Volume on Mechanical Complications after Resection Arthroplasty with Articulating Spacer.

Two-stage revision with an antibiotic-loaded cement articulating spacer is a standard treatment for chronic prosthetic knee infection (PKI); however, mechanical complications can occur during the spacer period. There is limited evidence on the association between surgeon volume and mechanical complications after resection arthroplasty (RA) using an articulating spacer. This study aimed to compare the rates of mechanical complications and reoperation after RA with articulating spacers by surgeons with high volumes (HV) and low volumes (LV) of RA performed and analyzed the risk factors for mechanical failure. The retrospective study investigated 203 patients treated with PKIs who underwent RA with articulating spacers and were divided according to the number of RAs performed by the surgeons: HV (≥14 RAs/year) or LV (<14 RAs/year). Rates of mechanical complications and reoperations were compared. Risk factors for mechanical complications were analyzed. Of the 203 patients, 105 and 98 were treated by two HV and six LV surgeons, respectively. The mechanical complication rate was lower in HV surgeons (3.8%) than in LV surgeons (36.7%) (p < 0.001). The reoperation rate for mechanical complications was lower in HV surgeons (0.9%) than in LV surgeons (24.5%) (p < 0.001). Additionally, 47.2% of patients required hinge knees after mechanical spacer failure. Medial proximal tibial angle < 87°, recurvatum angle > 5°, and the use of a tibial spacer without a cement stem extension were risk factors for mechanical complications. Based on these findings, we made the following three conclusions: (1) HV surgeons had a lower rate of mechanical complications and reoperation than LV surgeons; (2) mechanical complications increased the level of constraint in final revision knee arthroplasty; and (3) all surgeons should avoid tibial spacer varus malalignment and recurvatum deformity and always use a cement stem extension with a tibial spacer.

Medullary-Sparing Antibiotic Cement Articulating Spacer Reduces the Rate of Mechanical Complications in Advanced Septic Hip Arthritis: A Retrospective Cohort Study.

Antibiotic cement articulating spacers eradicate infection during a two-stage revision for advanced septic hip arthritis (ASHA); however, mechanical complications have been reported. We hypothesized that the rate of mechanical complications would be lower in medullary-sparing (MS) than in non-medullary-sparing (n-MS) articulating spacers. A retrospective study of ASHA using n-MS or MS spacers was conducted between 1999 and 2019. The rate of mechanical complications and reoperation and risk factors for mechanical complications were analyzed. The cohort included 71 n-MS and 36 MS spacers. All patients were followed up for 2 years. The rate of spacer dislocation was lower in MS (0%) than in n-MS spacers (14.1%; p = 0.014). The reoperation rate for mechanical complications was lower in MS (0%) than in n-MS spacers (12.7%; p = 0.019). The rate of a diaphyseal stem during reimplantation was lower in MS (0%) than in n-MS spacers (19.4%; p = 0.002). The identified risk factors for n-MS spacer dislocation were postoperative under-restored femoral head diameter ≥3 mm, femoral offset ≥3 mm, and surgical volume (≤6 resection arthroplasties per year). Both spacers controlled infection. However, MS spacers had a lower spacer dislocation and reoperation rate and avoided the diaphyseal stem during reimplantation. We recommend using MS spacers to restore native femoral head diameter and femoral offset when ASHA is treated by surgeons with lower surgical volumes.

Percutaneous Endoscopic Surgery Alone to Treat Severe Infectious Spondylodiscitis in the Thoracolumbar Spine: A Reparative Mechanism of Spontaneous Spinal Arthrodesis.

BACKGROUND: Infective spondylodiscitis has been treated solely with antibiotics based on the pathogen identified. Surgical intervention was used in cases of unidentified pathogens, failed antibiotic treatment, neurological deficit, or instability. The standard surgical procedure was debridement and interbody fusion with a bone graft through the anterior approach, followed by posterior instrumentation. Recently, percutaneous endoscopic surgery has been proven to be safe and effective for treating infectious spondylodiscitis. The results of endoscopy surgery treatment alone for infectious spondylodiscitis with severe bony destruction were analyzed in this study. OBJECTIVE: To describe the clinical and radiological outcomes in patients with infectious spondylodiscitis and severe bony destruction, who were treated with minimally invasive endoscopic surgery alone. STUDY DESIGN: Retrospective observational study (Institutional Review Board: CMUH 105-REC2-101). SETTING: An inpatient surgery center. METHODS: The study included 24 patients with infectious spondylodiscitis and severe bony destruction treated with endoscopy surgery. The patients were treated according to the endoscopic surgical protocol and were followed up for at least 5 years. A retrospective chart review was conducted to evaluate the locations, symptoms and signs, comorbidity, pain scale, and functional outcome. Laboratory data, such as erythrocyte sedimentation rate and C-reactive protein level, and clinical outcomes, including the pain scale, visual analogue scale, and functional score of Oswestry disability index, were recorded. All patients underwent a preoperative magnetic resonance imaging (MRI) scan and were carefully reviewed and classified based on the severity, including endplate erosion, bone edema (low T1, high T2), loss of vertebral height, paravertebral inflammation, paravertebral abscess, and epidural abscess. All patients underwent a plain film follow-up at 3, 6, 9, 12, and 18 months after surgery and computed tomography at 12 months postoperatively. RESULTS: The comorbidities of patients were categorized according to the Charlson Comorbidity Index. The results revealed 10 lesions on the thoracic or upper lumbar spine (between T10 and L3) and 14 on the lower lumbar spine (between L3 and S1). Bone destruction as a result of severe infection and loss of disc height was observed in most cases. During the final follow-up, no significant changes were observed in the sagittal alignment, and a kyphotic angle change of less than 10° was observed in 20 cases. Syndesmophyte formation along the anterior longitudinal ligament (ALL), paravertebral syndesmophyte formation, intervertebral bony fusion, and bony ankylosis of the facet joints in the form of osteophyte formation and fusion were noted. No posterior instrumentation surgery was performed for instability in our case series. LIMITATIONS: This was a retrospective observational clinical case series with small sample size. CONCLUSIONS: A trend of spontaneous spinal arthrodesis, including syndesmophyte formation along the ALL, paravertebral ligaments, direct intervertebral bone growth, and bony ankylosis of the facet joint were observed after a minimally invasive endoscopy treatment for infectious spondylodiscitis. The stability of the 3 columns resulted in segmental stability, which prevented the progression of the kyphotic deformity. Percutaneous endoscopic surgery is safe and effective for treating infectious spondylodiscitis even in patients with severe bony destruction.

Arthroscopy-Assisted Reduction and Internal Fixation versus Open Reduction and Internal Fixation for Glenoid Fracture with Scapular Involvement: A Retrospective Cohort Study.

BACKGROUND: We investigated the superiority of arthroscopy-assisted reduction and internal fixation (ARIF) to open reduction and internal fixation (ORIF) for treating glenoid fracture with scapular involvement. METHODS: We retrospectively enrolled patients with glenoid fracture who underwent ARIF or ORIF from 2010-2020. Radiographic outcomes were assessed, and clinical outcomes (active range of motion [ROM], visual analog scale [VAS], Constant, and Disabilities of the Arm, Shoulder and Hand [DASH]) were evaluated 12 months postoperatively. RESULTS: Forty-four patients with Ideberg type II-VI glenoid fractures (ARIF: 20; ORIF: 24; follow-up 12-22 months) were included. Union was achieved in all patients. Active ROM values were comparable between the approaches. Constant and DASH scores were non-significantly better with ARIF (90.9 ± 9.2 vs. 86.6 ± 18.1 [p = 0.341] and 6.8 ± 9.4 vs. 9.3 ± 21.3 [p = 0.626], respectively). However, VAS scores were significantly lower with ARIF (1.5 ± 0.6 vs. 2.7 ± 1.4, p = 0.001). Associated intra-articular lesions (articular depressions [80%], superior labral anterior-posterior tear [20%], labral tears [30%]) were found in most ARIF cases and were repaired during ARIF. CONCLUSIONS: For glenoid fracture with scapular involvement, ARIF allows accurate diagnosis of fracture pattern and the management of associated intra-articular lesions, with better pain control outcomes than ORIF. Thus, arthroscopy-assistant surgery should be considered in patient with glenoid fracture.

Posterior-Stabilized Antibiotic Cement Articulating Spacer With Endoskeleton-Reinforced Cam Reduces Rate of Post-Cam Mechanical Complications in Prosthetic Knee Infection: A Preliminary Study.

BACKGROUND: Posterior-stabilized antibiotic cement articulating spacers (PS spacers) reduce spacer mechanical complications in prosthetic knee infections (PKIs); however, joint dislocation after femoral cam fracture has been reported. We hypothesized that the rate of post-cam mechanical complications is lower in PS spacers with an endoskeleton-reinforced cam. METHOD: A retrospective study of PKIs using PS spacers with or without a Kirschner wire-reinforced cam (K-PS or nK-PS spacers, respectively) was conducted between 2015 and 2019. The rates of post-cam mechanical complications and reoperation, as well as risk factors for post or cam failure, were analyzed. RESULTS: The cohort included 118 nK-PS and 49 K-PS spacers. All patients were followed up for 2 years. The rate of joint subluxation/dislocation after femoral cam fracture was lower in K-PS (0%) than in nK-PS spacers (17.8%; P = .002). The reoperation rate for spacer mechanical complications was lower in K-PS (0%) than in nK-PS spacers (11.9%; P = .008). The identified risk factors for femoral cam fractures were body mass index ≥25 kg/m2, femoral spacer size ≤2, and surgical volume ≤12 resection arthroplasties per year. CONCLUSION: This preliminary study highlights that K-PS spacers have a lower rate of post-cam mechanical complications than nK-PS spacers. We recommend the use of PS spacers with endoskeleton-reinforced cam when treating PKIs performed by surgeons with lower surgical volumes, especially in patients with higher body mass index and smaller femoral spacer sizes.

Cruciate-Retaining vs Posterior-Stabilized Antibiotic Cement Articulating Spacers for Two-Stage Revision of Prosthetic Knee Infection: A Retrospective Cohort Study.

BACKGROUND: Antibiotic cement articulating spacers are recommended during 2-stage revision for prosthetic knee infection because of increased range of motion (ROM) and improved function; however, spacer mechanical complications have been reported. We aimed to determine the association between different constraints of articulating spacers and the rate of complications and infection eradication, functional outcomes, and ROM. METHODS: A retrospective study of prosthetic knee infection using cruciate-retaining (CR) or posterior-stabilized (PS) spacers was conducted between 2011 and 2018. The rate of spacer mechanical complications, infection eradication after reimplantation and reoperation, Hospital of Special Surgery (HSS) knee score, and ROM during the interim stage were analyzed. All patients were regularly followed up for 2 years. RESULTS: One hundred forty-one patients were included, with 66 CR and 75 PS spacers. Overall mechanical complication rate was lower in PS (9.3%) than in CR spacers (45.5%) (P < .001), especially in joint dislocation (1.3% vs 30.3%, respectively, P < .001). Overall reoperation rate was lower in PS (16.0%) than in CR spacers (36.4%) (P < .001), especially for mechanical complications (1.3% vs 24.2%, respectively, P < .001). HSS knee score was higher in PS (72.3) than in CR spacers (63.8) (P < .001). ROM was greater in PS (90.3°) than in CR spacers (80.6°) (P = .005), especially at maximum flexion (102.4° vs 89.6°, respectively, P = .003). Infection eradication was comparable between the spacers. CONCLUSION: Both spacers can control infection; however, PS spacers had a lower rate of mechanical complications and reoperation, better HSS knee scores, and greater ROM than CR spacers.

Anthropometric Factors on Safe Distances between Popliteal Vessels to the Femur for Cerclage Wiring of the Distal Femoral Fracture: A Magnetic Resonance Imaging Study.

Background and Objectives: The proximity of the popliteal vessels in the distal femur may increase the risk of iatrogenic vascular injury during cerclage wiring. In this study, the closest location and distance of the popliteal vessels to the femur was examined using magnetic resonance imaging (MRI). The associations between anthropometric factors and the distance that would guide the placement of wires safely during surgery were also identified. Materials and Methods: We reviewed adult knee magnetic resonance images and recorded: (1) the relation and the shortest horizontal distance (d-H) from the femoral cortex to the popliteal vessels in axial images and (2) the vertical distance (d-V) from the adductor tubercle to the axial level of the d-H values in coronal images. The effects of anthropometric factors (sex, age, body height, body weight, body mass index, thigh circumference, femoral length and femoral width) on these distances were analysed. Results: Analysis of 206 knee magnetic resonance images revealed that the closet locations of popliteal vessels were at the posteromedial aspect of the femur. The d-H and d-V were 7.38 ± 3.22 mm and 57.01 ± 11.14 mm, respectively, and were both shorter in women than in men (p < 0.001). Multivariate analysis identified thigh circumference and femoral length as the most influential factors for the d-H and d-V, respectively (p < 0.001). Linear regression demonstrated a strong positive linear correlation between the thigh circumference and the d-H and between the femoral length and the d-V (Pearson's r = 0.891 and 0.806, respectively (p < 0.001)). Conclusions: The closet location and distance of the popliteal vessels to the femur provide useful information for wire placement during distal femoral fracture surgery while minimising the risk of vascular injury. Given that patients with a smaller thigh circumference and a shorter femoral length are more likely to have a smaller d-H and a shorter d-V, respectively, cautious measures should be taken in such cases.

RTN4B-mediated suppression of Sirtuin 2 activity ameliorates ß-amyloid pathology and cognitive impairment in Alzheimer's disease mouse model.

Sirtuin 2 (SIRT2) is an NAD+ dependent deacetylase that is the most abundant sirtuin protein in the brain. Accumulating evidence revealed the role of SIRT2 in a wide range of biological processes and age-related diseases. However, the pivotal mechanism of SIRT2 played in Alzheimer's disease (AD) remains unknown. Here, we report that pharmacological inactivation of SIRT2 has a beneficial effect in AD. The deacetylase inhibitor of SIRT2 rescued the cognitive impairment in amyloid precursor protein/presenilin 1 transgenic mouse (APP/PS1 mouse), and the BACE1 cleavage was weakened to reduce the ß-amyloid (Aß) production in the hippocampus. Moreover, we firstly identified that Reticulon 4B (RTN4B) played a crucial role between SIRT2/BACE1 regulation in AD. RTN4B, as a deacetylation substrate for SIRT2, the deacetylation by SIRT2 drived the ubiquitination and degradation of RTN4B and then the disturbed RTN4B interacted with and influenced the expression of BACE1. When we overexpressed RTN4B in neurons of the hippocampus in the AD mouse model, the abnormal Aß accumulation and cognitive impairment were ameliorated, consistent with the results of SIRT2 inhibition in vivo. Moreover, we showed that the regulatory effect of SIRT2 on BACE1 is dependent on RTN4B. When RTN4B was knocked down, the effects of SIRT2 inhibition on the BACE1 level, Aß pathology, and AD-liked behaviors were also blocked. Collectively, we provide evidence that SIRT2 may be a potential target for AD; the new found SIRT2/RTN4B/BACE1 pathological pathway is one of the critical mechanisms for the improvement of SIRT2 on AD.

A prospective study of the factors associated with life quality during medical internship.

BACKGROUND: Medical interns' quality of life (QOL) are related to patient care quality, but the specific factors responsible for interns' QOL have not been well studied. Herein we presented this nationwide, prospective study to examine the impact of working hours restrictions on the QOL among medical interns. METHODS: The study recruited 295 medical interns (age: 25.3 ± 2.1, male: 68.1%) from all the 8 medical colleges in Taiwan during the 2012-2013 academic years. Subjects were assessed for QOL by brief version of the World Health Organization Quality of Life Assessment (WHOQOL-BREF) and the 9-item Patient Health Questionnaire (PHQ-9) before and every 3 months during their internship. We also investigated their demographic data, working hours, workload characteristics, such as specialties of internship rotation, acceptance of new patients after 24-hour, and no 24-hour off within 7 days, and self-reported patient related burnout. We used generalized estimation equation to delineate the change of WHOQOL-BREF and PHQ-9 scores during internship. We used multivariate regression analysis to examine the associated factors of QOL. RESULTS: WHOQOL-BREF score significantly decreased during internship (baseline: 60.0 ± 9.7, 53.7 ± 9.3 at 3 months, then remained at 55 after 9 months). Acceptance of new patients after 24 hours of continuous duty (ß = -2.089), no 24-hour off within 7 days (ß = -1.748), score of patient related burnout (ß = -2.50), and PHQ-9 depression score (ß = -1.02) were associated with lower WHOQOL-BREF score. Working hours was not significantly associated with the QOL (p = .6268). CONCLUSIONS: Our findings revealed interns' QOL significantly decreased during internship. Acceptance of new patients after 24-hour of continuous duty and patient related burnout predominantly impacted interns' QOL and depression more than working hours did.

Two Cases of De Novo Pathological Gambling Associated With Aripiprazole.

OBJECTIVES: Pathological gambling can be potentiated by treatment with dopamine agonists. Aripiprazole, bearing a partial agonist activity at dopamine D2 and D3 receptors, has also been linked to such a behavioral aberration, usually on subjects predisposed with tendency of impulsive or addictive behaviors. METHODS: Review of patient's medical records and literature review. RESULTS: Two young patients' pathological gambling emerged simply due to exposure to aripiprazole, neither related to manic or psychotic symptoms nor with history of addictive or impulsive behaviors. Their pathological gambling disappeared soon after switching aripiprazole to other antipsychotics. One patient has tested such a relationship by reexposure to aripiprazole while his compulsion to gamble recurred. CONCLUSIONS: In addition to previously recognized risk factors, pathological gambling might occur in young patients whose history did not reveal an addictive tendency while they were sensitive to the pharmacological effect, as well as adverse effects, of psychotropic agents.

A preliminary study of the novel antibiotic-loaded cement computer-aided design-articulating spacer for the treatment of periprosthetic knee infection.

BACKGROUND: In comparison to static spacers, articulating spacers have been shown to result in a similar infection eradication rate in two-stage revision of periprosthetic knee infections. However, the optimal construct for articulating spacers has not been identified yet. The aim of this study was to present a preliminary result of treatment for periprosthetic knee infection using a novel computer-aided design (CAD)-articulating spacer. METHODS: We retrospectively reviewed 32 consecutive cases of chronic periprosthetic knee infection occurring from January 2015 to December 2015. In these cases, we used an antibiotic-loaded, optimized CAD-articulating spacer based on the retrieved knee prosthesis. Evaluation included infection eradication rate, the Hospital of Special Surgery (HSS) knee score, range of motion (ROM), and spacer-related mechanical complications. All cases were regularly followed-up for 2 years minimum. RESULTS: Twenty-eight of 32 patients (87.5%) had infection eradication; 18 patients (56.3%) received reimplantation successfully. The mean interval between spacer insertion and reimplantation was 8.8 months (range 4.0-12.5 months). The mean HSS knee score and ROM significantly increased during each interval (p < 0.0001 for both). The mean HSS knee scores were 31.2 (range 20-48) at initial visit, 65.4 (range 60-78.8) at 1 month after spacer insertion, and 84.2 (range 78-90) at 3 months after reimplantation (p < 0.0001). The mean ROM were 72.0° (range 15-100°), 85.6° (range 35-110°), and 102.0° (range 80-122°), respectively (p = 0.002). Two (6.3%) spacer-related mechanical complications occurred. CONCLUSIONS: The CAD-articulating spacer in two-staged revision of periprosthetic knee infection significantly controlled infection, improved clinical outcomes, increased ROM, and decreased mechanical complications in the preliminary study. Further larger clinical studies are needed to confirm the findings presented here.

Probing the Roles of Calcium-Binding Sites during the Folding of Human Peptidylarginine Deiminase 4.

Our recent studies of peptidylarginine deiminase 4 (PAD4) demonstrate that its non-catalytic Ca2+-binding sites play a crucial role in the assembly of the correct geometry of the enzyme. Here, we examined the folding mechanism of PAD4 and the role of Ca2+ ions in the folding pathway. Multiple mutations were introduced into the calcium-binding sites, and these mutants were termed the Ca1_site, Ca2_site, Ca3_site, Ca4_site and Ca5_site mutants. Our data indicate that during the unfolding process, the PAD4 dimer first dissociates into monomers, and the monomers then undergo a three-state denaturation process via an intermediate state formation. In addition, Ca2+ ions assist in stabilizing the folding intermediate, particularly through binding to the Ca3_site and Ca4_site to ensure the correct and active conformation of PAD4. The binding of calcium ions to the Ca1_site and Ca2_site is directly involved in the catalytic action of the enzyme. Finally, this study proposes a model for the folding of PAD4. The nascent polypeptide chains of PAD4 are first folded into monomeric intermediate states, then continue to fold into monomers, and ultimately assemble into a functional and dimeric PAD4 enzyme, and cellular Ca2+ ions may be the critical factor governing the interchange.

Diagnosis of painful cemented vertebrae from failed vertebroplasty: modified dynamic radiographs play an important role.

PURPOSE: The diagnosis of painful cemented vertebrae resulting from failed PV is not clearly defined in literature. This report evaluates the effectiveness of modified dynamic radiographs in diagnosing painful cemented vertebrae resulting from failed PV. METHODS: From January 2011 to June 2015, 345 patients with a total of 399 VCFs underwent PV at our institution. Among the 345 patients, 27 patients underwent repeated PV at the cemented vertebrae because of persisting or recurrent pain after vertebroplasty. The prevertebroplasty examinations included routine radiographs, modified dynamic radiographs, and MRI. Kyphotic angles and the anterior vertebral body height (AVBH) were measured. The image findings in routine radiographs, modified dynamic radiographs, and MRI were compared. Finally, a visual analog scale was used to measure the outcome. RESULTS: The patients ranged in age from 67 to 90 years. MRI revealed a moderate amount of fluid (definite diagnosis of refracture) in the cemented vertebrae in seven patients, bone edema without fluid in nine patients, and bone edema with minimal fluid in ten patients. The rate of diagnosis of painful cemented vertebrae according to MRI was 27% (7/26). The difference in the kyphotic angle between sitting and supine cross-table lateral radiographs was -9.36° ± 5.20° (P < 0.001). The difference in AVBH was 8.08 ± 3.21 mm (P < 0.001). All 27 patients were confirmed to have dynamic mobility according to the modified dynamic radiographs. CONCLUSIONS: When the diagnosis of painful cemented vertebrae is questionable, modified dynamic radiographs can help diagnose painful cemented vertebrae resulting from failed PV.

[Protective Effects of Acupuncture Intervention Against Damage of Intestinal Mucosal Barrier Induced by 5-Fluorouracil in Rats].

OBJECTIVE: To observe the effect of acupuncture intervention on the diarrhea, mucosal thickness of the small intestine, plasma endotoxin (ET) and D-lactic acid (D-LA) contents, and diamine oxidase (DAO) activity in 5-Fluorouracil (5-Fu) induced intestinal mucosal damage rats, in order to provide an experimental basis for acupuncture therapy in improving chemotherapy-induced intestinal mucosa injury. METHODS: Thirty female SD rats were randomly divided into control group, model group and acupuncture group (n = 10 in each group). The intestinal mucosal damage model was established by intraperitoneal injection of 5-Fu (50 mg/kg, for six consecutive days). Acupuncture stimulation was applied to bilateral "Tianshu" (ST 25) and "Zusanli" (ST 36) once a day for six consecutive days. The changes of body weight and diarrhea score (0-3 points, according to Kurita's methods) as well as mucosal thickness of the small intestine were determined. The plasma ET and D-LA contents, and DAO activity were measured by ELISA. RESULTS: On the sixth day, the body weight was significantly higher in the acupuncture group than in the model group (P<0.05). After intraperitoneal injection of 5-Fu, both the incidence rate and average score of diarrhea reached the peak on the sixth day in the model and acupuncture groups, and were significantly lower in the acupuncture group than in the model group (P<0.01). On the seventh day, the mucosal thickness of small intestine was significantly lower in the model group than in the control group (P<0.05), but had no remarkable changes after acupuncture intervention( P>0.05). The contents of plasma ET and D-LA and DAO activity level were significantly higher in the model group than in the control group, and markedly decreased in the acupuncture group than in the model group (P<0.01). CONCLUSION: Acupuncture intervention can lower the incidence rate and average score of diarrhea and down-regulate the increased plasma ET and D-LA contents and DAO activity levels in 5-Fu induced intestinal mucosal damage rats, suggesting a somewhat protective effect of acupuncture against chemotherapy induced damage of the intestinal mucosal barrier.

Distances between bony landmarks and adjacent nerves: anatomical factors that may influence retractor placement in total hip replacement surgery.

BACKGROUND: Retractor placement is a leading cause of intraoperative nerve injury during total hip replacement (THR) surgery. The sciatic nerve, femoral nerve, and superior gluteal nerve are most commonly affected. This study aimed to identify the distances from bony landmarks in the hip to the adjacent nerves on magnetic resonance imaging (MRI) and the associations between anatomical factors and these distances that would guide the placement of retractors during THR surgery, in order to minimize the risk of nerve injury. METHODS: We reviewed hip MRIs of 263 adults and recorded the distances from (1) the anterior acetabular rim to the femoral nerve; (2) the superior acetabular rim to the superior gluteal nerve; (3) the posterior acetabular rim to the sciatic nerve; and (4) the greater trochanter to the sciatic nerve. The effects of anatomical factors (i.e., gender, age, body height, body mass index (BMI), pelvic width, and acetabular version and morphology) on these distances were analyzed. RESULTS: Distances from bony landmarks to adjacent nerves (in cm) were 2.06 ± 0.44, 2.23 ± 0.28, 1.94 ± 0.81, and 4.83 ± 0.26 for the anterior acetabular rim, superior acetabular rim, posterior acetabular rim, and greater trochanter, respectively, and were shorter in women than in men (P < 0.001). Multivariate analysis identified body height as the most influential factor (P < 0.001). Linear regression demonstrated a strong positive linear correlation between body height and these distances (Pearson's r = 0.808, 0.823, 0.818, and 0.792, respectively (P < 0.001)). CONCLUSIONS: The distances from bony landmarks to adjacent nerves provide useful information for placing retractors without causing nerve injury during THR surgery. Shorter patients will have shorter distances from bony landmarks to adjacent nerves, prompting more careful placement of retractors.

Multifaceted interactions and regulation between antizyme and its interacting proteins cyclin D1, ornithine decarboxylase and antizyme inhibitor.

Ornithine decarboxylase (ODC), cyclin D1 (CCND1) and antizyme inhibitor (AZI) promote cell growth. ODC and CCND1 can be degraded through antizyme (AZ)-mediated 26S proteasomal degradation. This paper describes a mechanistic study of the molecular interactions between AZ and its interacting proteins. The dissociation constant (Kd) of the binary AZ-CCND1 complex and the respective binding sites of AZ and CCND1 were determined. Our data indicate that CCND1 has a 4-fold lower binding affinity for AZ than does ODC and an approximately 40-fold lower binding affinity for AZ than does AZI. The Kd values of AZ-CCND1, AZ-ODC and AZ-AZI were 0.81, 0.21 and 0.02 µM, respectively. Furthermore, the Kd values for CCND1 binding to the AZ N-terminal peptide (AZ34-124) and AZ C-terminal peptide (AZ100-228) were 0.92 and 8.97 µM, respectively, indicating that the binding site of CCND1 may reside at the N-terminus of AZ, rather than the C-terminus. Our data also show that the ODC-AZ-CCND1 ternary complex may exist in equilibrium. The Kd values of the [AZ-CCND1]-ODC and [AZ-ODC]-CCND1 complexes were 1.26 and 4.93 µM, respectively. This is the first paper to report the reciprocal regulation of CCND1 and ODC through AZ-dependent 26S proteasomal degradation.

Structural characteristics of the nonallosteric human cytosolic malic enzyme.

Human cytosolic NADP(+)-dependent malic enzyme (c-NADP-ME) is neither a cooperative nor an allosteric enzyme, whereas mitochondrial NAD(P)(+)-dependent malic enzyme (m-NAD(P)-ME) is allosterically activated by fumarate. This study examines the molecular basis for the different allosteric properties and quaternary structural stability of m-NAD(P)-ME and c-NADP-ME. Multiple residues corresponding to the fumarate-binding site were mutated in human c-NADP-ME to correspond to those found in human m-NAD(P)-ME. Additionally, the crystal structure of the apo (ligand-free) human c-NADP-ME conformation was determined. Kinetic studies indicated no significant difference between the wild-type and mutant enzymes in Km,NADP, Km,malate, and kcat. A chimeric enzyme, [51-105]_c-NADP-ME, was designed to include the putative fumarate-binding site of m-NAD(P)-ME at the dimer interface of c-NADP-ME; however, this chimera remained nonallosteric. In addition to fumarate activation, the quaternary structural stability of c-NADP-ME and m-NAD(P)-ME is quite different; c-NADP-ME is a stable tetramer, whereas m-NAD(P)-ME exists in equilibrium between a dimer and a tetramer. The quaternary structures for the S57K/N59E/E73K/S102D and S57K/N59E/E73K/S102D/H74K/D78P/D80E/D87G mutants of c-NADP-ME are tetrameric, whereas the K57S/E59N/K73E/D102S m-NAD(P)-ME quadruple mutant is primarily monomeric with some dimer formation. These results strongly suggest that the structural features near the fumarate-binding site and the dimer interface are highly related to the quaternary structural stability of c-NADP-ME and m-NAD(P)-ME. In this study, we attempt to delineate the structural features governing the fumarate-induced allosteric activation of malic enzyme.

Kirschner wire-guided technique for inserting a second needle into inadequately filled vertebrae in vertebroplasty: a technical report.

BACKGROUND CONTEXT: Absence or inadequate filling of cement in the fractured vertebrae can cause unsatisfactory results in a vertebroplasty. Repeated needle insertion can reduce the incidence of recollapse at the cemented vertebrae. However, when inserting the second needle in the usual method, it takes the same time and radiation exposure as the first needle. PURPOSE: To report a Kirschner wire-guided technique for inserting a second needle into inadequately filled vertebrae in vertebroplasty that can make the procedure simple, effective, and, most importantly, reduce the radiation exposure. STUDY DESIGN: Description of a modified surgical technique with retrospective data analysis. PATIENT SAMPLE: From January 2012 to December 2012, 87 percutaneous vertebroplasties were performed in our department to treat painful osteoporotic compression fractures. Seven adult patients (five women, two men; mean age: 75.7 years) had inadequate cement filling in the treated vertebrae that required the insertion of a second needle. OUTCOME MEASURES: Back pain was measured using the visual analog scale (VAS). The post-vertebroplasty anterior vertebral height and local kyphotic angle were used as the radiologic parameters. Intraoperative procedure time and fluoroscopy shots and postoperative complication were also evaluated. METHODS: The stylus of the first needle was inserted into the trocar to push the cement out of the trocar. The stylus was removed, a small diameter K-wire was inserted into the trocar, and the trocar was then removed. A second (new) trocar was inserted into the vertebral body following the track of the K-wire. When the new trocar reached the posterior 1/4 of the vertebral body, the K-wire was removed, the stylus was inserted, and the new needle was advanced to the anterior third of the vertebra. Cement was then injected into the new area until the filling was adequate. RESULTS: The immediate post-vertebroplasty anterior vertebral height was 23.31±1.95 mm, changed to 22.20±3.72 mm at final follow-up. The VAS decreased from a mean of 8.4 before vertebroplasty to 1.6 at the final follow-up. The follow-up duration ranged from 6 to 15 months (mean 12.6 months). There was no case of recollapse of the cemented vertebrae and no procedure-related complications. The procedure time of historical controls was 153.5 seconds, which reduced to 47.9 seconds by using this technique. The fluoroscopy shots of historical controls were 9.7 shots, which reduced to 2 shots by using this technique. CONCLUSIONS: This report suggests that Kirschner wire-guided technique for inserting a second needle during vertebroplasty could make the procedure simple, effective, and, most importantly, reduce the procedure time and radiation exposure.

Comparison of CID versus ETD-based MS/MS fragmentation for the analysis of doubly derivatized steroids.

Electrospray ionization coupled with collision-induced dissociation (CID) and tandem mass spectrometry (MS/MS) is a commonly used technique to analyze the chemical composition of steroids. However, steroids are structurally similar compounds, making it difficult to interpret their product-ion spectra. Electron transfer dissociation (ETD), a relatively new technique for protein and peptide fragmentation, has been shown to provide more detailed structural information. In this study, we compared the ability of CID with that of ETD to differentiate between eight 3,20-dioxosteroids that had been derivatizated with a quaternary ammonium salt, Girard reagent P (GirP), at room temperature or after exposure to microwave irradiation to generate doubly charged ions. We found that the derivatization of steroid with GirP hydrazine occurred in less than 10 min when the reaction was carried out in the presence of microwave irradiation compared to 30 min when the reaction was carried out at room temperature. According to the MS/MS spectra, CID provided rich, structurally informative ions; however, the spectra were complex, thereby complicating the peak assignment. In contrast, ETD generated simpler spectra, making it easier to recognize individual peaks. Remarkably, both CID and ETD were allowed to differentiate of steroid isomers, 17α-hydroxyprogesterone (17OHP) and deoxycorticosterone (DOC), but the signature ions obtained from CID were less intense than those generated by ETD, which generated much clearer spectra. These results indicate that ETD in conjunction with CID can provide more structural information for precise characterization of steroids.