Closing-wedge Osteotomies: Can We Do and Teach Better?

BACKGROUND

Wedge osteotomies are ubiquitous in pediatric orthopaedics and limb deformity surgery; however, there is no universally preferred methodology for these procedures. This study aims to determine the relative accuracy and effectiveness of several measuring and marking methods to guide best practices for wedge-shaped osteotomies in long bones.

METHODS

An observational cohort study was completed. Orthopaedic residents (postgraduate years 1 to 5) completed 30-degree wedge osteotomies on a sawbone (Pacific Research Lab) femur utilizing a standard oscillating saw under 3 measuring conditions: (1) no measurement tool, (2) 30-degree triangle, and (3) goniometer, in combination with 2 different marking methods: (1) marking pen or (2) pin placement. Demographic characteristics and osteotomy performance (quality, completion time, and accuracy) were assessed. Quality was ranked as perfect (1), mild step-off (2), or gross surface irregularity (3). Multivariate regressions and analysis of variance were performed comparing demographics, osteotomy performance, and measuring methods.

RESULTS

Twenty-four residents were included for analysis; 6 were female (25%). Female sex was independently associated with longer completion time when evaluating all combined scenarios (138 vs. 99 s, P =0.003) without differences in surface quality or angle accuracy. There were no significant associations between measuring technique and accuracy or surface quality, but use of the goniometer and the triangle both were associated with significantly longer completion time compared with no visual aid ( P =0.002 and 0.007). When controlling for measuring technique, use of the pen as a marking technique had significantly shorter completion times ( P <0.001), higher surface quality ( P <0.001), and better accuracy ( P <0.001) than guide pins.

CONCLUSIONS

We recommend the use of a marking pen in combination with the surgeon's preferred measuring guide to optimize trainees' performance of closing wedge osteotomies. Future research is necessary to corroborate these findings in a higher fidelity setting, such as a cadaveric study. Further, while male residents complete wedge osteotomies quicker than female residents, quality and accuracy are comparable among trainees. Slower pace should not be conflated with poor performance but rather should inform effective intraoperative teaching for diverse trainees.

Trauma Isn't One Size Fits All: How Online Support Communities Point to Different Diagnostic Criteria for C-PTSD and PTSD

Reddit has provided rich data on mental health discourse. The present study uses 40,335 online posts from Reddit communities to investigate how language can contribute to the understanding of PTSD and C-PTSD. The results showed distinct language patterns in the use of first-person pronouns, cognitive processing, and emotion words, suggesting that they are separate disorders with different effects on survivors. Further, while some social media studies have differentiated submissions and comments, few have investigated the language changes between these contexts. Post-hoc results showed a clear distinction between two contexts across several linguistic markers. Discussion and future directions are explored.

Modifiable and non-modifiable risk factors for failure of non-operative treatment of pediatric forearm fractures: Where can we do better?

Introduction

Distal third forearm fractures are common fractures in children. While outcomes are generally excellent, some patients fail initial non-operative management and require intervention. The purpose of this study is to identify independent risk factors associated with failure of closed reduction.

Methods

We conducted a retrospective review of distal third forearm fractures in children treated with closed reduction and casting. Patients were divided into two cohorts-those who were successfully closed reduced and those who failed initial non-operative management. Demographic characteristics, cast type, cast index, radiographic fracture, soft tissue characteristics, and quality of reduction were analyzed between groups.

Results

A total of 207 children treated for distal third forearm fractures were included for analysis. A total of 190 (91.8%) children maintained their reduction while 17 (8.2%) failed initial non-operative management. Modifiable risk factors associated with loss of reduction on univariate analysis included the use of a long arm cast (p = 0.003), increased post-reduction displacement (p = 0.02), and increased post-reduction angular deformity (p = 0.01). Non-modifiable risk factors included increased body mass index (p = 0.02), increased presenting fracture displacement (p = 0.002), and increased width of the soft tissue envelope at the fracture site (p = 0.0001). The use of long arm casts (13% vs 2%, odds ratio = 6.44) and soft tissue width (60.6 vs 50.4 mm, odds ratio = 1.1) remained significant risk factors for loss of reduction after multivariate analysis.

Conclusion

Both larger soft tissue envelope at the site of the fracture and long arm cast immobilization are independently associated with an increased risk of failing initial closed reduction in distal third forearm fractures in the pediatric population.

Level of evidence

level III Case Control Study.

Slow-motion smartphone video improves interobserver reliability of gait assessment in ambulatory cerebral palsy

Purpose

Structured visual gait assessment is essential for the evaluation of pediatric patients with neuromuscular conditions. The purpose of this study was to evaluate the benefit of slow-motion video recorded on a standard smartphone to augment visual gait assessment.

Methods

Coronal and sagittal plane videos of the gait of five pediatric subjects were recorded on a smartphone, including four subjects with ambulatory cerebral palsy and one subject without gait pathology. Twenty-one video scorers were recruited and randomized to evaluate slow-motion or normal-speed videos utilizing the Edinburgh Visual Gait Score. The slow-motion group (N = 11) evaluated the videos at one-eighth speed, and the normal-speed group (N = 10) evaluated the same videos at normal speed. Interrater reliabilities were determined by calculating intraclass correlation coefficients for each group as a whole, for each Edinburgh Visual Gait Score item, and after stratification by evaluator experience level.

Results

The slow-motion group exhibited an intraclass correlation coefficient of 0.65 (95% confidence interval: 0.58-0.73), whereas the normal-speed group exhibited an intraclass correlation coefficient of 0.57 (95% confidence interval: 0.49-0.65). For less-experienced scorers, intraclass correlation coefficients of 0.62 (95% confidence interval: 0.53-0.71) and 0.50 (95% confidence interval: 0.40-0.59) were calculated for slow motion and normal speed, respectively. For more-experienced scorers, intraclass correlation coefficients of 0.69 (95% confidence interval: 0.61-0.76) and 0.67 (95% confidence interval: 0.58-0.75) were calculated for slow motion and normal speed, respectively.

Conclusions

Visual gait assessment is enhanced by the use of slow-motion smartphone video, a tool widely available throughout the world with no marginal cost.

Level of evidence

level I, randomized study.

Nonmetallic Anterior Hemiepiphysiodesis of the Distal Femur with a Low-Profile, Pretensioned Implant: A Case Report

CASE

A 14-year-old adolescent boy with left-sided spastic hemiplegic cerebral palsy presented with a 14° left knee flexion contracture and resultant gait disturbance in the setting of an open distal femoral physis. He underwent subsequent anterior distal femur hemiepiphysiodesis with a suture anchor-based, nonmetallic implant. He achieved full correction at the 1-year follow-up and underwent uncomplicated implant removal.

CONCLUSION

A low-profile, suture-based implant used for pediatric knee flexion deformity may allow surgeons to control growth in a reversible fashion by tensioning the physis while possibly avoiding some of the complications associated with currently used implants.

The Utility of Virtual Reality in Orthopedic Surgical Training

OBJECTIVE

To examine the efficacy of virtual reality (VR) to prepare surgical trainees for a pediatric orthopedic surgery procedure: pinning of a slipped capital femoral epiphysis (SCFE).

DESIGN

Participants were randomly assigned to a standard, study guide (SG) group or to a VR training group. All participants were provided a technique video and SG; the VR group additionally trained via an Osso VR surgical trainer (ossovr.com) with real-time feedback and coaching from an attending pediatric orthopedic surgeon. Following training, participants performed a SCFE guidewire placement on a SawBones model embedded in a soft-tissue envelope (SawBones model 1161). Participants were asked to achieve "ideal placement" based on the training provided. Participants were evaluated on time, number of pin "in-and outs," penetration of the articular surface, angle between the pin and the physis, distance from pin tip to subchondral bone and distance from the center-center point of the epiphysis.

SETTING

Orthopedic Institute for Children, Los Angeles, CA.

PARTICIPANTS

Twenty fourth-year medical students, first- and second-year orthopedic residents without experience with the SCFE procedure.

RESULTS

Twenty participants were randomized to SG (n = 10) or VR (n = 10). Average time to final pin placement was 19% shorter in VR group (706 vs 573 seconds, p = 0.26). When compared to SG, the VR group had, on average, 70% less pin in-and-outs (1.7 vs 0.5, p = 0.28), 50% less articular surface penetrations (0.4 vs 0.2, p = 0.36), and 18% smaller distance from pin tip to subchondral bone on lateral view (7.1 vs 5.8 mm, p = 0.42). Moreover, the VR group had a lower average angle deviation between pin and line perpendicular to the physis on coronal view (4.9° vs 2.5°, p < 0.05).

CONCLUSIONS

VR training is potentially more effective than traditional preparatory methods. This pilot study suggests that VR training may be a viable surgical training tool, which may alleviate constraints of time, money, and safety concerns with resultant broad applicability for surgical education.

Mobility impairment and life satisfaction in the Northern Region of Malawi

Background

There exist many psychosocial sequelae associated with mobility impairment, especially in low-resource settings where access to mobility assistive devices is limited.

Objectives

This study aims to (1) define the burden and presenting aetiologies of mobility impairment in the rural Northern Region of Malawi and (2) assess the relationship between physical disability, life satisfaction and access to mobility aids.

Methods

At mobility device donation clinics throughout the Northern Region of Malawi, adults living with mobility impairment were surveyed with a demographic questionnaire and a series of validated surveys to assess their physical activity levels (Global Physical Activity Questionnaire [GPAQ]), degree of mobility impairment (Washington Group Extended Set Questions on Disability) and life satisfaction (patient-reported outcomes measurement information systems satisfaction with participation in social roles and general life satisfaction).

Results

There were 251 participants who qualified for inclusion, of which 193 completed all surveys. Higher physical activity scores were positively correlated with increased life satisfaction: (1) satisfaction with participation in social roles (0.481, p < 0.0001) and (2) general life satisfaction (0.230, p < 0.001). Respondents who had previously used a formal mobility device reported 235.5% higher physical activity levels ([139.0%, 333.0%], p = 0.006), significantly higher satisfaction with participation in social roles ([0.21, 6.67], p = 0.037) and equivocally higher general life satisfaction ([-1.77, 3.84], p = 0.470).

Conclusion

Disability and mental health do not exist in isolation from one another. Given the positive correlations between formal mobility device usage and both physical activity and life satisfaction, interventions that increase access to mobility-assistive devices in undertreated populations are imperative.

Contribution

This study contributes to the understanding of the complex relationship between physical disability, access to mobility aids, and life satisfaction. Results from this study suggest the potential benefit that increasing access to mobility aids may have in improving the quality of life of mobility impaired persons in resource-limited settings, such as the Northern Region of Malawi.

The Utility of Routine Radiographic Monitoring in Pediatric Osteoarticular Infections

BACKGROUND

Pediatric musculoskeletal (MSK) infections broadly include isolated osteomyelitis (OM), septic arthritis (SA), and combined infections (OM+SA). These diagnoses are often monitored with serum inflammatory markers and serial radiographs to monitor treatment response and development of negative sequelae, despite limited data supporting these practices. The purpose of this study is to evaluate the utility of obtaining serial radiographic follow-up for pediatric osteoarticular infections.

METHODS

An institutional review board-approved retrospective review was completed. Children 18 years and below admitted to a single institution with a culture/biopsy-proven diagnosis of OM, SA, or OM+SA. All postdischarge radiographs were reviewed and retrospectively categorized as either routine (scheduled) or reactive. Routine radiographs were obtained regardless of clinical presentation. Reactive radiographs were obtained in patients presenting with the sign of an altered clinical course. Negative sequelae, defined as growth arrest/disturbance, pathologic fracture, recurrent MSK infection, and underlying neoplastic process, were recorded and tracked. Descriptive statistics were used to summarize demographic and outcome variables. Number needed to screen (NNS) was defined as the inverse of the incidence of negative sequelae detected.

RESULTS

A total of 131 patients were included for analysis, with a mean age of 11.9 years (SD: 4.96 y). Ninety (69%) patients were diagnosed and treated for OM, 25 (19%) for SA, and 16 (12%) for combined infections. A total of 329 radiographs were obtained following discharge. Of those obtained, 287 (88%) were routine, resulting in the detection of 2 (0.7%) negative sequelae and a resultant NNS of 143 radiographs (95% confidence interval: 36-573). The remaining 39 were reactive radiographs, resulting in the detection of 2 (5.1%) negative sequelae with an NNS of 20 radiographs (95% confidence interval: 5-78).

CONCLUSIONS

While radiographs remain a widely utilized tool to screen for the development of negative sequelae in pediatric osteoarticular infections, they rarely alter management in the absence of other concerning clinical signs or symptoms such as recurrent fevers, swelling of the extremity, or limb deformity. Moreover, routine radiographic surveillance should be replaced with a reactive radiographic protocol.

LEVEL OF EVIDENCE

Level III-retrospective comparative study.

The utility of echocardiography in paediatric patients with musculoskeletal infections and bacteremia

PURPOSE

The clinical utility of echocardiography in the setting of a positive blood culture in paediatric patients presenting with osteomyelitis (OM) and/or septic arthritis (SA).

METHODS

Retrospective review between 2013 and 2019: Patients < 18 years with OM, SA or combined infection (OM+SA) were included. Patients were excluded for immunodeficiency, loss of follow-up or penetrating infection. Charts with positive blood cultures were reviewed for echocardiography on that admission. Demographic variables were compared utilizing the Student's t-test and Fisher's exact test. A multivariable linear regression model was constructed to examine the association between echocardiography and length of stay, controlling for age, sex, fever, white blood cell (WBC) on admission, antibiotic administration and surgery performed.

RESULTS

Of 157 patients with OM, SA or combined infection, 44 had a positive blood culture. In all, 26 had an echocardiogram, and none showed endocarditis. Echocardiography was independently associated with a 6.2-day length of stay increase. WBC count and surgical intervention demonstrated a trend toward significance in length of stay, with each WBC unit increase associated with a 0.53-day increase. Surgical intervention was associated with an average 6.3-day length of stay decrease.

CONCLUSION

No patient had a positive echocardiogram, and no changes in management were initiated. However, an echocardiogram increased stay by 6.2 days. In addition to costs associated with increased stay, patients were billed between $1460 and $1700 per echocardiogram. The utility of echocardiograms in the setting of bacteremia associated with musculoskeletal infections in the paediatric population should be re-examined, and guidelines should be updated to reflect the cost-benefit analysis.

LEVEL OF EVIDENCE

III.

Design of a Microfluidic Bleeding Chip to Evaluate Antithrombotic Agents for Use in COVID-19 Patients

Introduction

Interventions that could prevent thrombosis, clinical decompensation, and respiratory compromise in patients with novel coronavirus disease (COVID-19) are key to decrease mortality rate. Studies show that profound cytokine release and excessive activation of blood coagulation appear to be key drivers of COVID-19 associated mortality. Since limited in vitro methods exist for assessing the effects of anticoagulants on hemostasis, the development of novel therapies to safely prevent thrombosis in COVID-19 patients relies on preclinical animal models and early phase human trials. Herein we present the design of a microfluidic “bleeding chip” to evaluate the effects of antithrombotic therapies on hemostatic plug formation in vitro.

Methods

The design of the microfluidic device consists of two orthogonal channels: an inlet that serves as a model blood vessel, and a bleeding channel to model hemostatic plug formation at sites of compromised endothelial barrier function. This is achieved by placing a series of 3 pillars spaced 10 μm apart at the intersection of the two channels. The pillars and bleeding channel are coated with the extracellular matrix protein collagen.

Results

Perfusion of human whole blood through the microfluidic bleeding chip led to initial platelet adhesion and aggregation at the pillars followed by hemostatic plug formation and occlusion of the bleeding channel.

Conclusions

Safe and effective mitigating agents are needed for treatment and prevention of thrombotic complications in COVID-19 patients. This simple microfluidic device holds potential to be developed into a tool for assessing the effects of anticoagulant therapy on hemostasis.

Time-to-Surgery for Definitive Fixation of Hip Fractures: A Look at Outcomes Based Upon Delay

The morbidity and mortality after hip fracture in the elderly are influenced by non-modifiable comorbidities. Time-to-surgery is a modifiable factor that may play a role in postoperative morbidity. This study investigates the outcomes and complications in the elderly hip fracture surgery as a function of time-to-surgery. Using the American College of Surgeons-National Surgical Quality Improvement Program data from 2011 to 2012, a study population was generated using the Current Procedural Terminology codes for percutaneous or open treatment of femoral neck fractures (27235, 27236) and fixation with a screw and side plate or intramedullary fixation (27244, 27245) for peritrochanteric fractures. Three time-to-surgery groups (<24 hours to surgical intervention, 24-48 hours, and >48 hours) were created and matched for surgery type, sex, age, and American Society of Anesthesiologists class. Time-to-surgery was then studied for its effect on the post-surgical outcomes using the adjusted regression modeling. A study population of 6036 hip fractures was created, and 2012 patients were assigned to each matched time-to-surgery group. The unadjusted models showed that the earlier surgical intervention groups (<24 hours and 24-48 hours) exhibited a lower overall complication rate (P = .034) compared with the group waiting for surgery >48 hours. The unadjusted mortality rates increased with delay to surgical intervention (P = .039). Time-to-surgery caused no effect on the return to the operating room rate (P = .554) nor readmission rate (P = .285). Compared with other time-to-surgeries, the time-to-surgery of >48 hours was associated with prolonged total hospital length of stay (10.9 days) (P < .001) and a longer surgery-to-discharge time (hazard ratio, 95% confidence interval: 0.74, 0.69-0.79) (P < .001). Adjusted analyses showed no time-to-surgery related difference in complications (P = .143) but presented an increase in the total length of stay (P < .001) and surgery-to-discharge time (P < .001). Timeliness of surgical intervention in a comorbidity-adjusted population of elderly hip fracture patients causes no effect on the overall complications, readmissions, nor 30-day mortality. However, time-to-surgery of >48 hours is associated with costly increase in the total length of stay, including an increased post-surgery-to-discharge time.

Vitamin D Insufficiency and Fracture Risk in Urban Children

BACKGROUND

Investigation into the role of vitamin D in fractures in the pediatric population has been limited despite estimates that as many as 70% of American children have inadequate vitamin D levels (measured as 25-hydroxyvitamin D, 25(OH)D). The purpose of this study was to evaluate vitamin D's role in pediatric fracture risk by comparing 25(OH)D between fractured and nonfractured cohorts.

METHODS

A 12-month prospective case-control study was completed in children aged 2 to 14 years in an urban, academic hospital. Sixty fractured children requiring conscious sedation or general anesthesia for management were compared with 60 nonfractured controls. All participants and their guardians were surveyed for low bone density risk factors, and total serum 25(OH)D was measured. Statistical analysis was completed using Student t tests, χ tests, analysis of variance, and logistic regression models.

RESULTS

After controlling for age and daily sun exposure, lower total serum 25(OH)D was associated with higher fracture risk (odds ratio=0.94; 95% confidence interval, 0.90-0.99; P=0.023). In the fractured cohort, 6 (10%) patients were deficient (25(OH)D<20 ng/mL) and 33 (55%) were insufficient (25(OH)D, 20 to 30 ng/mL). Of the nonfractured population, 8 (13%) were deficient and 19 (32%) were insufficient. There were more insufficient patients in the fractured than in the nonfractured cohort (odds ratio=2.99; 95% confidence interval, 1.27-7.0; P=0.037).

CONCLUSIONS

Higher fracture incidence is associated with serum 25(OH)D insufficiency. Hypovitaminosis D may place the pediatric population at increased risk for fracture. Consideration should be given to routine assessment of vitamin D in fractured children.

LEVEL OF EVIDENCE

Prognostic level III-prospective case-control study.

Brace Success Is Related to Curve Type in Patients with Adolescent Idiopathic Scoliosis

BACKGROUND

Curve magnitude and skeletal maturity are important factors in determining the efficacy of bracing for the treatment of adolescent idiopathic scoliosis, but curve morphology may also affect brace success. The purpose of this study was to determine the influence of curve morphology on the response to bracing with a thoracolumbosacral orthosis (TLSO).

METHODS

A retrospective review of patients managed with an orthosis for the treatment of adolescent idiopathic scoliosis who were prospectively enrolled at the initiation of brace wear and followed through completion of bracing or surgery was performed. Inclusion criteria were main curves of 25° to 45° and a Risser stage of 0, 1, or 2 at the time of brace prescription. Compliance with bracing was measured with Maxim Integrated Thermochrons. Radiographs made at brace initiation, brace cessation, and final follow-up were used to retrospectively categorize curves with use of the modified Lenke (mLenke) classification system and more broadly to categorize them as main thoracic or main lumbar. The effect of morphology on outcome was evaluated using chi-square and Fisher exact tests.

RESULTS

One hundred and sixty-eight patients were included. There was no difference in curve magnitude at the time of brace initiation (p = 0.798) or in average hours of daily brace wear (p = 0.146) between groups. The rate of surgery or progression of the curve to ≥50° was 34.5% (29 of 84) in mLenke-I curves, 54.5% (6 of 11) in mLenke-II curves, 29.4% (10 of 34) in mLenke-III curves, 17.6% (3 of 17) in mLenke-V curves, and 13.6% (3 of 22) in mLenke-VI curves. There were no mLenke-IV curves at the time of brace initiation. The rate of surgery or progression to ≥50° was 34.1% (44 of 129) in the combined thoracic group and 15.4% (6 of 39) in the combined lumbar group (p = 0.0277). In brace-compliant patients (>12.9 hours/day), the rate of surgery or progression to ≥50° was 30.3% (20 of 66) in main thoracic curves and 5.3% (1 of 19) in main lumbar curves (p = 0.0239). One-tenth of curves changed morphology during bracing. The rate of surgery or progression to ≥50° was 35.8% (43 of 120) in persistent main thoracic curves, 20.0% (6 of 30) in persistent main lumbar curves, 12.5% (1 of 8) in main thoracic curves that became main lumbar curves, and 0% (0 of 9) in main lumbar curves that became main thoracic curves (p = 0.0383).

CONCLUSIONS

Thoracic curves are at greater risk for brace failure than lumbar curves are despite similar initial curve magnitudes and average amount of daily brace wear. A change in curve pattern may imply flexibility and is associated with brace success. Patients with thoracic curves should be counseled accordingly.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Interhospital Variability in Perioperative Red Blood Cell Ordering Patterns in United States Pediatric Surgical Patients

OBJECTIVE

To evaluate perioperative red blood cell (RBC) ordering and interhospital variability patterns in pediatric patients undergoing surgical interventions at US children's hospitals.

STUDY DESIGN

This is a multicenter cross-sectional study of children aged <19 years admitted to 38 pediatric tertiary care hospitals participating in the Pediatric Health Information System in 2009-2014. Only cases performed at all represented hospitals were included in the study, to limit case mix variability. Orders for blood type and crossmatch were included when done on the day before or the day of the surgical procedure. The RBC transfusions included were those given on the day of or the day after surgery. The type and crossmatch-to-transfusion ratio (TCTR) was calculated for each surgical procedure. An adjusted model for interhospital variability was created to account for variation in patient population by age, sex, race/ethnicity, payer type, and presence/number of complex chronic conditions (CCCs) per patient.

RESULTS

A total of 357 007 surgical interventions were identified across all participating hospitals. Blood type and crossmatch was performed 55 632 times, and 13 736 transfusions were provided, for a TCTR of 4:1. There was an association between increasing age and TCTR (R(2) = 0.43). Patients with multiple CCCs had lower TCTRs, with a stronger relationship (R(2) = 0.77). There was broad variability in adjusted TCTRs among hospitals (range, 2.5-25).

CONCLUSIONS

The average TCTR in US children's hospitals was double that of adult surgical data, and was associated with wide interhospital variability. Age and the presence of CCCs markedly influenced this ratio. Studies to evaluate optimal preoperative RBC ordering and standardization of practices could potentially decrease unnecessary costs and wasted blood.

Isolation of sterol mutants inChlamydomonas reinhardi: Chromatographic analyses

Several sterol mutants ofChlamydomonas reinhardi were isolated by selecting for single colonies resistant to the polyene antibiotic, nystatin. The sterol profiles of three isolates-KD7, KD16, and KD21-as well as a wild type strain (137C) were determined by gas liquid chromatography and mass spectrometry. The wild type strain contained ergosterol (C28-5,7,22-triene) as the predominant sterol, with smaller amounts of a C28-5,7-diene, a C28-7-ene, and C-24 ethyl analogs of these three sterols. The three mutants had altered sterol composition, but none required exogenous sterol for growth. KD7 contained a C28-5,7,22,25-tetraene, a C28-5,7,25-triene, a C28-7,25-diene, and three C-24 ethyl analogs. The lesion in KD7 is apparently an inability to reduce the C-25 double bond required for the biosynthesis of ergosterol and an ethyl analog. The predominant sterols accumulated by KD16 and KD21 were a C28-5,7-diene, a C28-7-ene, and C-24 ethyl versions of these two sterols, suggesting that these strains are 22(23)-desaturase mutants.

Perioperative Outcomes Following Unilateral Versus Bilateral Total Knee Arthroplasty

Simultaneous bilateral total knee arthroplasty (SB-TKA) is potentially a cost saving manner of caring for patients with bilateral symptomatic knee arthritis. We performed a retrospective analysis using the 2010-2012 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) to evaluate the risk of perioperative complication following SB-TKA. Demographic characteristics, comorbidities, and 30-day complication rates were studied using a propensity score-matched analysis comparing patients undergoing unilateral TKA and SB-TKA. A total of 4489 patients met the inclusion criteria, of which 973 were SB-TKA. SB-TKA was associated with increased overall complications (P = 0.023), medical complications (P = 0.002) and reoperation (OR 2.12, P = 0.020). Further, total length of hospital stay (4.0 vs 3.4 days, P < 0.001) was significantly longer following bilateral surgery.

The Second National Ballistics Imaging Comparison (NBIC-2)

In response to the guidelines issued by the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLD/LAB-International) to establish traceability and quality assurance in U.S. crime laboratories, NIST and the ATF initiated a joint project, entitled the National Ballistics Imaging Comparison (NBIC). The NBIC project aims to establish a national traceability and quality system for ballistics identifications in crime laboratories utilizing ATF's National Integrated Ballistics Information Network (NIBIN). The original NBIC was completed in 2010. In the second NBIC, NIST Standard Reference Material (SRM) 2461 Cartridge Cases were used as reference standards, and 14 experts from 11 U.S. crime laboratories each performed 17 image acquisitions and correlations of the SRM cartridge cases over the course of about half a year. Resulting correlation scores were collected by NIST for statistical analyses, from which control charts and control limits were developed for the proposed quality system and for promoting future assessments and accreditations for firearm evidence in U.S. forensic laboratories in accordance with the ISO 17025 Standard.

Inhibition of Essential Bacterial Peptidyl-tRNA Hydrolase Activity by Tropical Plant Extracts

Peptidyl-tRNA Hydrolase (Pth) is a highly conserved, essential enzyme in bacteria. It removes the peptide portion from peptidyl-tRNA, returning free tRNAs to participate in translation. Build-up of peptidyl-tRNAs is toxic and defects in Pth function result in cell death. Herein we use in vitro activity of recombinant E. coli Pth to screen tropical plant extracts for inhibition. Multiple extracts were found to have inhibitory activity with some exhibiting different inhibitory effects depending on extraction conditions. IC50values ranged from 0.02 to > 53.8 μg of extract per 1 unit of Pth, holding promise for in vivo screening. The inhibitory components in these extracts may serve as lead compounds for development of novel antibacterials.

Inhibition of essential bacterial peptidyl-tRNA hydrolase activity by tropical plant extracts

Peptidyl-tRNA Hydrolase (Pth) is a highly conserved, essential enzyme in bacteria. It removes the peptide portion from peptidyl-tRNA, returning free tRNAs to participate in translation. Build-up of peptidyl-tRNAs is toxic and defects in Pth function result in cell death. Herein we use in vitro activity of recombinant E. coli Pth to screen tropical plant extracts for inhibition. Multiple extracts were found to have inhibitory activity with some exhibiting different inhibitory effects depending on extraction conditions. IC50 values ranged from 0.02 to > 53.8 microg of extract per 1 unit of Pth, holding promise for in vivo screening. The inhibitory components in these extracts may serve as lead compounds for development of novel antibacterials.

Systematic generation of all nonequivalent closest-packed stacking sequences of length N using group theory

An algorithm has been developed that generates all of the nonequivalent closest-packed stacking sequences of length N. There are 2(N) + 2(-1)(N) different labels for closest-packed stacking sequences of length N using the standard A, B, C notation. These labels are generated using an ordered binary tree. As different labels can describe identical structures, we have derived a generalized symmetry group, Q approximately equal to D(N) x S(3), to sort these into crystallographic equivalence classes. This problem is shown to be a constrained version of the classic three-colored necklace problem.

Quantifying distortion from ideal closest-packing in a crystal structure with analysis and application

A parameter, U(cp), that quantifies the distortion of the anion skeleton in a crystal from ideal closest-packing has been developed. It is a measure of the average isotropic displacement of the observed anions from their ideal equivalents. An ideal closest-packed structure can be fit to an observed structure by varying the radius of the ideal spheres, orientation and translation, such that U(cp) is minimized. Ideal structures were fit to the M1M2TO(4) polymorphs, pyroxenes and kyanite. The distortions of these crystals were analyzed in terms of the two parameters, U(cp) and the ideal radius. Changes in structures due to temperature, pressure and compositional effects were characterized in terms of these parameters.

A unique approach to multidisciplinary cancer education

BACKGROUND

Almost every health care worker, regardless of specialty, interacts with individuals who have histories of cancer. Some health care workers are relatively unfamiliar with the cancer experience and those who are familiar with it are interested in additional information.

METHOD

The Mayo Clinic Cancer Center Education Subcommittee designed a monthly educational program titled Cancer Connections: A Multidisciplinary Update. The goals of this program were to provide: 1) up-to-date information about cancer issues, 2) a better understanding of various team members' roles in caring for people with cancer, 3) insight into patients' responses to the diagnosis and treatment of their cancers, and 4) greater awareness of the resources available to cancer patients and their families. Each session consists of a "panel" of presenters: three healthcare professionals and a patient.

RESULTS AND DISCUSSION

The success of this program is reflected in the regular high attendance and consistently positive evaluations of the participants.

The polyglutamine expansion in spinocerebellar ataxia type 6 causes a beta subunit-specific enhanced activation of P/Q-type calcium channels in Xenopus oocytes

Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited degenerative disorder of the cerebellum characterized by nearly selective and progressive death of Purkinje cells. The underlying mutation in SCA6 consists of an expansion of a trinucleotide CAG repeat in the 3' region of the gene, CACNA1A, encoding the alpha(1A) subunit of the neuronal P/Q-type voltage-gated calcium channel. Although it is known that this mutation results in an expanded tract of glutamine residues in some alpha(1A) splice forms, the distribution of these splice forms and the role of this mutation in the highly selective Purkinje cell degeneration seen in SCA6 have yet to be elucidated. Using specific antisera we demonstrate that the pathological expansion in SCA6 can potentially be expressed in multiple isoforms of the alpha(1A) subunit, and that these isoforms are abundantly expressed in the cerebellum, particularly in the Purkinje cell bodies and dendrites. Using alpha(1A) subunit chimeras expressing SCA6 mutations, we show that the SCA6 polyglutamine expansion shifts the voltage dependence of channel activation and rate of inactivation only when expressed with beta(4) subunits and impairs normal G-protein regulation of P/Q channels. These findings suggest the possibility that SCA6 is a channelopathy, and that the underlying mutation in SCA6 causes Purkinje cell degeneration through excessive entry of calcium ions.

Spinocerebellar ataxia type 6: gaze-evoked and vertical nystagmus, Purkinje cell degeneration, and variable age of onset

Spinocerebellar ataxia type 6 (SCA6) was recently identified as a form of autosomal dominant cerebellar ataxia associated with small expansions of the trinucleotide repeat (CAG)n in the gene CACNL1A4 on chromosome 19p13, which encodes the alpha1 subunit of a P/Q-type voltage-gated calcium channel. We describe clinical, genetic, neuroimaging, neuropathological, and quantitative oculomotor studies in four kindreds with SCA6. We found strong genetic linkage of the disease to the CACNL1A4 locus and strong association with the expanded (CAG)n alleles in two large ataxia kindreds. The expanded alleles were all of a single size (repeat number) within the two large kindreds, numbering 22 and 23 repeat units. It is noteworthy that the age of onset of ataxia ranged from 24 to 63 years among all affected individuals, despite the uniform repeat number. Radiographically and pathologically, there was selective atrophy of the cerebellum and extensive loss of Purkinje cells in the cerebellar cortex. In addition, clinical and quantitative measurement of extraocular movements demonstrated a characteristic pattern of ocular motor and vestibular abnormalities, including horizontal and vertical nystagmus and an abnormal vestibulo-ocular reflex. These studies identify a distinct phenotype associated with this newly recognized form of dominant SCA.

Imaging of cerebral activation at 1.5 T: optimizing a technique for conventional hardware

PURPOSE

To empirically optimize a two-dimensional magnetic resonance (MR) imaging technique for detecting changes in signal intensity during cerebral activation with a standard clinical imager.

MATERIALS AND METHODS

Visual activation experiments were performed while imaging parameters were manipulated in a serial fashion, to test their effect on the percentage change in signal intensity (PCSI). The parameters tested were section thickness, echo time (TE), field of view (FOV), flip angle, radio-frequency (RF) spoiling, number of readout points, and number of signals averaged.

RESULTS

The PCSI for visual activation experiments was typically in the 1%-5% range. The best results were achieved with a small section thickness, long TE, and large FOV. Variations in other acquisition parameters had a negligible influence on the PCSI.

CONCLUSION

Good results can be obtained at functional MR imaging with standard 1.5-T hardware. Markedly improved results can be obtained by optimizing several key variables, namely, section thickness, TE, and FOV.

Sensory motor cortex: correlation of presurgical mapping with functional MR imaging and invasive cortical mapping

PURPOSE

To describe a clinically useful application of functional magnetic resonance (MR) imaging--presurgical mapping of the sensory motor cortex--and to validate the results with established physiologic techniques.

MATERIALS AND METHODS

Functional MR mapping of the sensory motor cortex was performed in two women, aged 24 and 38 years. Both had intractable, simple partial motor seizures due to tumors located in or near the sensory motor cortex. They subsequently underwent invasive cortical mapping--direct cortical stimulation and/or sensory-evoked-potential recording--to localize the affected sensory motor area prior to tumor resection.

RESULTS

In both patients, the functional MR study demonstrated task activation of the sensory motor cortex. In both cases, results of cortical functional mapping with invasive techniques matched those obtained with functional MR imaging.

CONCLUSION

Presurgical mapping of the sensory motor cortex is a potentially useful clinical application of functional MR imaging.

Interleaved echo planar imaging on a standard MRI system

This work describes an interleaved echo planar imaging (EPI) method for use on a standard whole body scanner. The data acquisition is divided into two to eight repetitions rather than one to two, as implemented by dedicated EPI systems. Interleaving allows the use of a lower sampling bandwidth with a significant increase in signal-to-noise. The method also has the advantages of relative ease of implementation, no need for postprocessing to remove image distortion, and no need for shimming on a case-by-case basis. The interleaved EPI method was applied to two applications ideally suited to EPI: breathhold T2-weighted abdominal imaging and functional imaging. In vivo liver-lesion contrast as measured in a 35-patient study showed increased contrast for the interleaved EPI by an average factor of 1.21 (+/- 0.34) over conventional spin-echo imaging. CNR measurements showed the EPI to be comparable with conventional spin echo with a relative factor of 1.00 (+/- 0.36). Functional imaging with an eight-shot interleaved EPI sequence provided 128 x 128 images of cerebral activation during bilateral finger tapping.

Increased neopterin levels in brains of patients with human immunodeficiency virus type 1 infection

Postmortem levels of native neopterin (D-erythro-neopterin) were measured in cerebral cortical samples from 44 human immunodeficiency virus type 1-infected and eight uninfected, nonneurological control patients. Cerebral cortical gray and white matter neopterin levels for the controls ranged from 0.5 to 7.2 pmol/mg of protein in contrast to neopterin levels in brains of the virus-infected patients, which frequently were more than threefold and occasionally more than 30-fold higher than mean control levels. Cortical neopterin levels did not correlate with severity of the acquired immunodeficiency syndrome dementia complex, but subcortical levels correlated with the presence of active human immunodeficiency virus type 1 infection, as reflected by pathological evidence of multinucleated giant cell encephalitis. Evidence of opportunistic cytomegalovirus infections in approximately 25% of the human immunodeficiency virus type 1-infected patients was associated with enhanced levels of neopterin in frontal cortex.

Differential induction of indoleamine-2,3-dioxygenase (IDO) by interferon-gamma in human gynecologic cancer cells

Induction of indoleamine-2,3-dioxygenase (IDO) by interferon-gamma (IFN-gamma) is thought to be one mechanism underlying IFN-gamma's antineoplastic properties. Since clinical trials with IFN-gamma have yielded variable efficacy in treating cancers of gynecological origin, we tested the effects of IFN-gamma on cell growth and IDO activity in cell lines from seven gynecologic and five breast cancers. At a dose of 250 IU/ml, IFN-gamma suppressed cell growth and induced IDO activity in one cervical (C41), one vulva (A431), one breast (HS578T) and two ovarian (OVCAR-3, CAOV-3) cancer cell lines. Differing inhibition of cell growth, but with no induction of IDO activity, was found with IFN-gamma treatment of the other cell lines.

Angiosarcoma after tylectomy and radiation therapy for carcinoma of the breast

BACKGROUND

Angiosarcoma (AS) is an uncommon tumor that rarely develops after external beam radiation therapy (EBRT). Thirty-six cases have been reported in the literature.

METHODS

The authors present two additional cases. Each of these patients received breast-conserving treatment for breast carcinoma that consisted of tylectomy and EBRT. In each case, AS developed in the field of prior irradiation.

RESULTS

Currently, seven cases of AS after radiation therapy for breast-conserving treatment of breast carcinoma have been reported. The average time interval between the administration of radiation therapy and the development of AS is 8.6 years.

CONCLUSIONS

This complication is rare and should not influence the decision to offer breast-conserving therapy to patients. However, patients should be informed that AS may develop as a result of radiation therapy.

Isolation and identification of major metabolites of tixocortol pivalate in human urine

The metabolism of tixocortol pivalate (PIVALONE), an anti-inflammatory steroid without systemic glucocorticoid effects, has been investigated in man. The analysis was conducted using urine samples collected from two volunteers who had received a 2-g oral dose of 14C-tixocortol pivalate as an oral suspension. Metabolites were purified and isolated from urine by normal phase HPLC, and structural identification was achieved by desorption chemical ionization/NH3 and electron impact/direct line introduction mass spectrometry. Unchanged tixocortol pivalate was not detected in urine; all metabolites were sulfo- and glucurono-conjugates. Metabolites were identified in the neutral steroid fraction obtained after hydrolysis of conjugates. Metabolic transformations in common with cortisol were reduction of the 3-keto, delta 4 system, reduction of the C-20 carbonyl group, oxidation of the C-11 alcohol, and cleavage of the side chain at C-17. Specific metabolic pathways involving the C-21 thiol ester function were transformations into methylthio, methylsulfinyl and methylsulfonyl derivatives, and a reductive cleavage of the C-21-S bond leading to 21-methyl structures. Since none of these metabolites had binding affinity for glucocorticoid receptors in vitro, fast and extensive transformation of tixocortol pivalate into inactive metabolites provides an explanation for the large dissociation between the topical and systemic activities of this drug.

A rostral-caudal concentration gradient in cerebrospinal fluid adrenocorticotropin

In two separate experiments, cerebrospinal fluid (CSF) adrenocorticotropin immunoreactive (ACTH-IR) concentrations in the rhesus monkey followed a significant rostral-caudal gradient. In the first study, CSF was sampled from an indwelling catheter in awake animals. The mean ACTH-IR concentration in the cisternal region was 12.3 pg/ml, as compared to 8.56 pg/ml in the lumbar region. In the second study, CSF was sampled in a different group of monkeys by percutaneous puncture at the cisterna magna and at L5-L6. In this study, the mean ACTH-IR concentration in samples collected from the cistern was also greater than the concentration from L5-L6. In addition, a significant correlation within subjects was found between samples collected from the two sites (r = 0.86). These results demonstrate that the site of CSF sampling is a variable in determining CSF ACTH-IR concentrations and suggest that lumbar CSF ACTH-IR concentrations in humans may be interpreted as indexes of ACTH changes at higher levels in the central nervous system.

Propionyl coenzyme A carboxylase deficiency presenting as non-ketotic hyperglycinaemia

A 4-month-old girl presented with myoclonic seizures and an electroencephalogram showing hypsarrhythmia. Hyperglycinuria and a cerebrospinal fluid to plasma glycine ratio of 0.2 suggested the diagnosis of non-ketotic hyperglycinaemia. Propionic acid and methyl citric acid were present in the urine, and propionyl coenzyme A carboxylase was deficient in leucocytes and fibroblasts. The ketotic and non-ketotic hyperglycinaemias cannot be differentiated by CSF: plasma glycine ratios.

Conjugation of fatty acids to DDT in the rat: possible mechanism for retention

Palmitic, stearic, oleic, and linoleic fatty acid conjugates of DDT were retained in vivo in livers and spleens of male and female rats given chronic i.p. injections of DDT. These DDT fatty acid conjugates could also be produced in vitro in a rat liver coenzyme A fortified microsomal system using the DDT hydroxylated metabolite DDOH as the substrate. The phenomenon of fatty acid conjugation to DDT may be a mechanism by which it is retained in the body and ultimately exerts its toxic effect.

Evidence for the epoxide-diol pathway in the biotransformation of mephenytoin

A dihydrodiol metabolite of mephenytoin (5-dihydroxycyclohexadienyl)-5-ethyl-3-methylhydantoin and other mono- and dihydroxylated and N-demethylated metabolites were identified in urine from a male epileptic patient receiving therapy with mephenytoin (300 mg/day). Metabolites, extracted from urine before and after enzymatic hydrolysis, were derivatized with a trimethylsilyl reagent and analyzed by combined gas chromatography and mass spectrometry. Two previously unreported metabolites were characterized: 5-ethyl-5-(di-hydroxyphenyl)-3-methylhydantoin and 5-ethyl-5-(hydroxy-methoxy-phenyl)-3-methylhydantoin. The structures of several other metabolites were confirmed: N-demethylmephenytoin, 5-ethyl-5-hydroxyphenylhydantoin, 5-ethyl-5-hydroxyphenyl-3-methylhydantoin and mephenytoin dihyrodiol. The dihydrodiol metabolite was of special interest since it was probably produced via an epoxide intermediate, 5-(epoxy-cyclohexadienyl)-5-ethyl-3-methylhydantoin. Previous reports have demonstrated that epoxides of this structural class are extremely reactive compounds, capable of alkylating biologic macromolecules. Covalent binding of the mephenytoin epoxide to macromolecules may be an important factor in the production of adverse and sometimes fatal side effects observed in patients receiving long-term therapy with mephenytoin.

Characterization of mephenytoin metabolites in human urine by gas chromatography and mass spectrometry

Metabolites of mephenytoin (5-ethyl-3-methyl-5-phenylhydantoin) were characterized in human urine following chromatography on XAD-2 resin, permethylation, and combined gas chromatography and mass spectrometry. Four glucuronide metabolites previously unidentified in man were characterized as their permethylated derivatives by chemical-ionization and electron-impact mass spectrometry. These metabolites included 5-ethyl-5-(hydroxyphenyl)-3-methylhydantoin O-glucuronide; 5-hydroxyethyl-3-methyl-5-phenyl-hydantoin O-glucuronide; 5-ethyl-5-(hydroxymethoxyphenyl)-3-methylhydantoin O-glucuronide; and a metabolite tentatively identified as 5-ethyl-5-phenylhydantoin N3-glucuronide in which both N-demethylation and glucuronide conjugation of the hydantoin ring have occurred. Mephenytoin, N-demethylmephenytoin, 5-ethyl-5-(hydroxyphenyl)-3-methylhydantoin, and 5-ethyl-5-(hydroxymethoxyphenyl)-3-methylhydantoin were characterized in extracts of enzymatically hydrolyzed urine.

Mass spectrometry of some ultraviolet absorbing derivatives of sugars and related alditols: identification in biologic fluids after separation by high performance liquid chromatography

The 70 eV electron impact mass spectra of the acyclic perbenzoyl 0-benzyloximes of several mono- and disaccharides of clinical interest and the perbenzoates of certain related alditols have been obtained and compared with those of other similar derivatives studied previously. In general, the spectra of the benzyloximes contain molecular ions and characteristic fragments due to [C6H5]+,[C7H7]+,[C6H5CO]+ and [C6H5CooH]+., losses of HCHO, C6H5COO. and C6H5COOH, and cleavages along the carbon chain. The most unique ions in these spectra arise from the combined loss of C7H7. and C6H5COO.from the molecular ion: m/z 191 (C3), m/z 339 (deoxy-C5), m/z 459 (C5), m/z 473 (deoxy-C6), and m/z 593 (C6). The alditol benzoates fragment similarly, but they do not yield molecular ions. These data are being used to help confirm the identities of carbohydrates in biologic fluids fractionation by high performance liquid chromatography, prior to the establishment of routine quantitative assays for several of these compounds.

Does the conventional cystogram exaggerate reflux?

We studied 35 patients with anterograde and retrograde cystography. Many patients who had reflux on retrograde cystography either did not have reflux or the reflux was reduced significantly on anterograde cystography. Furthermore, when reflux was seen on anterograde cystography it appeared to have more prognostic value than when seen on retrograde cystography. The question is raised of whether much reflex seen on retrograde cystography is not actually an artifact of the examination and does not exist beyond circumstances of the test.

Analysis of mono- and disaccharides by high-performance liquid chromatography of the benzyloxime-perbenzoyl derivatives

A group of biologically important mono- and disaccharides are separated by high-performance liquid chromatography of the benzyloxime-perbenzoyl derivatives on a normal-phase microparticulate column with a hexane-dioxane mixture as the eluting solvent. A single, quantifiable derivative of each sugar is formed easily. These derivatives are detected by UV absorption at either 230 or 254 nm, with a sensitivity in the picomole range at the former wavelength. The sugars in the residues from the evaporation of small aliquots of biologic fluids (10-100 microliter) are derivatized without prior isolation and are determined quantitatively by the use of appropriate internal standards. The analyses could be performed routinely with a simple, inexpensive instrument.

Characterization of glucuronide metabolites of carbamazepine in human urine by gas chromatography and mass spectrometry

Glucuronide metabolites of carbamazepine (5 H-dibenz[b,f]azepine-5-carboxamide) were identified in human urine following chromatography on XAD-2 resin, permethylation, and combined gas chromatography and mass spectrometry with an SE-30 capillary column. Eight glucuronide metabolites, previously unidentified in man, were characterized as their permethylated derivatives. These included carbamazepine N-glucuronide (M+. 482), three isomers of dihydroxycarbamazepine O-glucuronide (M+. 542), three isomers of hydroxymethoxycarbamazepine O-glucuronide (M+. 542), and one isomer of hydroxycarbamazepine O-glucuronide (M+. 512). Other glucuronide metabolites, previously identified following enzymatic hydrolysis, were characterized as the unhydrolyzed, permethylated glucuronides, 10,11-dihydro-10,11-di--hydroxy carbamazepine O-glucuronide (M+. 544), and three isomers of monohydroxycarbamazepine O-glucuronide (M+. 512).

Determination of disaccharides in feces by permethylation and gas chromatography: rapid screening for carbohydrate intolerance in children

Disaccharides can be identified and determined quantitatively in fecal specimens by permethylation of the components in crude supernatants followed by isothermal gas chromatographic separation on OV-17 columns. The method provides a rapid screening procedure for detecting patients suspected of having a carbohydrate intolerance secondary to intestinal disaccharidase deficiency.

Identification of drugs, drug metabolites, and other compounds in urine by permethylation and gas-phase analysis

A small aliquot of urine (50-200 mul) is evaporated to dryness, the residue permethylated with the methylsulfinylmethide carbanion and methyl iodide, and the product mixture separated and analyzed by GC and GC-MS. Certain drugs (especially the anticonvulsants), drug metabolites, mono-, di-, and trisaccharides, and organic acids, including fatty acids and glucuronides, can be identified in the mixture. The technique is probably useful mainly as a screening method for the detection of any of these types of compounds in urine.