A Longitudinal Perspective on Conversion to Amputation for Combat-Related Extremity Injuries Treated With Flap-Based Limb Salvage

OBJECTIVES

To define the rate and primary drivers behind early and late amputation after flap-based limb salvage in the setting of combat extremity trauma.

DESIGN

Retrospective review.

SETTING

Level II trauma center.

PATIENTS

307 (303 men, 4 women) patients who underwent flap-based limb salvage treatment between 2003 and 2014.

INTERVENTION

We reviewed patient medical records, radiographs, and clinical photographs.

MAIN OUTCOME MEASUREMENTS

Early and late amputation rates, time to amputation, reason for amputation.

RESULTS

307 patients accounted for 323 limbs that underwent flap-based limb salvage treatment (187 lower extremities, 136 upper extremities). A total of 58 extremities (18%) initially treated with flap-based limb salvage ultimately underwent amputation at a median of 480 days (IQR, 285-715 days) from injury. Periarticular fractures and lower extremity injuries were risk factors for early and late amputation. Other independent risk factors for early amputation were flap complications and vascular injuries, whereas risk factors for late amputation were fractures that went on to nonunion.

CONCLUSIONS

This study highlights that a subset of patients ultimately require major limb amputation despite having achieved what is initially considered "successful" limb salvage. Flap-related complications, vascular injury, and lower extremity site of injury were associated with early amputation after successful expeditionary efforts at limb preservation. Conversion to late amputation was associated with lower extremity periarticular fractures and fracture nonunion. Chronic pain and persistent limb dysfunction were the most common reasons for late amputation.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Utilization of a Clinic-Based Hand Surgery Procedure Room in the US Military Health System: A Performance Improvement Analysis of Resource Savings and Patient Satisfaction

PURPOSE

Recent studies examining the implementation of clinic-based procedure rooms (PRs) for wide-awake hand surgery have reported cost reduction, decreased burden on hospital systems, and improved patient satisfaction. This study evaluates other resource savings, primarily time spent by patients in the hospital.

METHODS

Thirty-two patients were enrolled in a PR or the operating room group for prospective evaluation. Time spent in the hospital on the day of surgery, several preprocedure appointments, complications, and cost comparisons were evaluated between the two groups. Patient-reported outcomes were also evaluated with postoperative surveys assessing anxiety, pain, and satisfaction.

RESULTS

Significant time savings were noted between the groups. The median time spent in the hospital on the day of surgery for the patients in the operating room group was 256 minutes versus 90 minutes for the PR group, a time savings of approximately 3 hours. Eight additional preoperative clinic visits for operating room patients were generated compared with no additional preoperative visits for PR patients. Cost savings for surgeries performed in the clinic-based procedure amounted to $232,411. No postoperative complications were observed in the clinic setting.

CONCLUSIONS

Continued utilization of the clinical PR for select hand surgery procedures will reduce the cost and time burdens for procedures while maintaining satisfaction and safety.

CLINICAL RELEVANCE

A clinic-based PR for performing minor hand surgeries saves the patient time and ostensibly allows the operating room to be used for more complex surgeries that are not easily amenable to a wide-awake in-clinic procedure.

Beyond Limb Salvage: Limb Restoration Efforts Following Remote Combat-Related Extremity Injuries Optimize Outcomes and Support Sustained Surgical Readiness

INTRODUCTION

As the combat operational tempo of the military conflicts in Iraq and Afghanistan has declined over the last decade, there has been a decrease in the number of patients requiring acute limb salvage. In their place, a growing population of patients with persistent functional deficits, pain, and inadequate soft tissue coverage stemming from prior limb salvage strategies have returned to our institution seeking revision surgery. Herein, we examine our institution's evolving surgical approach to extremity reconstruction from 2011 through 2019, culminating in the development of our limb restoration concept. We also discuss the impact of this orthoplastic approach on the acute management of complex extremity trauma and its role in providing sustained surgical readiness during interwar years.

MATERIALS AND METHODS

We retrospectively reviewed all limb reconstructive procedures performed at our tertiary care military treatment facility between September 1, 2011 to December 31, 2019 to characterize the trends in extremity reconstruction procedures performed at our institution. Cases were identified as limb restoration procedures if they involved secondary/revision reconstructive procedures designed to optimize function, treat pain, or improve the durability of the injured extremity following initial reconstruction efforts.

RESULTS

Nearly 500 limb restoration procedures were performed during the study period. These procedures steadily increased since 2011, reaching a maximum of 120 in 2018. Orthoplastic procedures such as osseointegration, targeted muscle reinnervation, regenerative peripheral nerve interface, agonist-antagonist myoneural interface, and soft tissue resurfacing flap reconstruction accounted for the rise in secondary/revision reconstruction performed during this time period.

CONCLUSION

Limb restoration is a collaborative orthoplastic approach that utilizes state-of-the-art surgical techniques for treating complex extremity trauma. Although limb restoration originally developed in response to managing the long-term sequelae of combat extremity trauma, the concept can be adapted to the acute management setting. Moreover, limb restoration provides military surgeons with a means for maintaining critical war-time surgical skills during the current low casualty rate era. Level of Evidence: V, therapeutic.

Bilateral Chronic Quadriceps Tendon Ruptures Treated with Hamstring Autograft Reconstruction: A Case Report

CASE

A 30-year-old semiprofessional football player presented with chronic bilateral quadriceps tendon ruptures. Both quadriceps tendon ruptures were unsuitable for isolated primary repair because of tendon retraction and immobility. A novel reconstruction technique using semitendinosus and gracilis tendon autografts was performed to restore both lower extremities' disrupted extensor mechanisms. At the final follow-up, the patient regained excellent motion of both knees and returned to high-intensity activity.

CONCLUSION

Chronic quadriceps tendon ruptures present challenges related to tendon quality and mobilization. Reconstruction with hamstring autograft using a Pulvertaft weave through the retracted quadriceps tendon in a high-demand athletic patient represents a novel approach for treating this injury.

The Incidence, Risk Factors, and Complications Associated With Surgical Delay in Multilevel Fusion for Adult Spinal Deformity

STUDY DESIGN

Retrospective database review.

OBJECTIVES

The incidence and risk factors for surgical delay of multilevel spine fusion for adult spinal deformity (ASD), and the complications corresponding therewith, remain unknown. The objectives of this study are to assess the incidence and risk factors for unexpected delay of elective multilevel spinal fusions on the date of surgery as well as the postoperative complications associated with these delays.

METHODS

We conducted a retrospective review of the ACS-NSQIP database on patients undergoing elective spinal instrumentation of greater than 7 levels for ASD between the years 2005 and 2015. Preoperative risk factors for delay and postoperative complications were compared between the cohorts of patients with and without surgical delays.

RESULTS

Multivariate analysis of 1570 (15.6%) patients identified advanced age, male sex, American Society of Anesthesiologists (ASA) Class 4, and history of smoking as independent risk factors for delay. Patients experiencing surgical delay demonstrated longer operative times, increased intraoperative bleeding, longer hospitalizations, and significantly higher rates of postoperative complications. Patients experiencing delay demonstrated an almost 7-fold increase in mortality rate (3.4% vs 0.5%, P < .001).

CONCLUSIONS

Delays in elective surgical care for spinal deformity are negatively related to patient outcomes. Advanced age, male sex, increased ASA class, and a history of smoking cigarettes place patients at risk for surgical delay of multilevel spinal fusion. Patients experiencing surgical delay are at higher risk for postoperative complications, including a 7-fold increase in mortality. These findings suggest that ASD surgery should be postponed in patients experiencing a delay, until modifiable risk factors can be medically optimized, and perhaps postponed indefinitely in those with nonmodifiable risk factors.

Institutional Experience and Orthoplastic Collaboration Associated with Improved Flap-based Limb Salvage Outcomes

BACKGROUND

Flap-based limb salvage surgery balances the morbidity and complexity of soft tissue transfer against the potential benefit of preserving a functional limb when faced with a traumatized extremity with composite tissue injury. These composite tissue injuries are well suited for multidisciplinary management between orthopaedic and plastic surgeons. Thus, it makes intuitive sense that a collaborative, orthoplastic approach to flap-based limb salvage surgery can result in improved outcomes with decreased risk of flap failure and other complications, raising the question of whether this orthoplastic team approach should be the new standard of care in limb salvage surgery.

QUESTIONS/PURPOSES

(1) Is there an association between increased annual institutional volume and perioperative complications to include free and local flap failure (substantial flap viability loss necessitating return to the operating room for debridement of a major portion or all of the flap or amputation)? (2) Is an integrated orthoplastic collaborative approach to managing combat-related traumatic injuries of the extremities individually associated with a decreased risk of flap failure and overall flap-related complications? (3) What other factors, such as location of injury, injury severity score, and initial inpatient length of stay, were associated with flap necrosis and flap-related complications?

METHODS

We performed a retrospective review of the electronic medical records of all patients who underwent flap-based limb salvage for combat-related extremity trauma in the United States Military Health System's National Capital Region between January 1, 2003 and December 31, 2012. In total, 307 patients underwent 330 flap procedures. Of the 330 flaps, 59% (195) were local or pedicled flaps and 41% (135) were free flaps. Patients were primarily male (99% [303]), with a median (interquartile range) age of 24 years old (IQR 21 to 29), and 87% (267 of 307) of injuries were sustained from a blast mechanism. We collected data on patient demographics, annual case volume involving flap coverage of extremities, mechanism of injury, flap characteristics, perioperative complications, flap failure, flap revision, isolated orthopaedic management versus an integrated orthoplastic approach, and other salvage procedures. For the purposes of this study, orthoplastic management refers to operative management of flap coverage with microvascular surgeons present for soft tissue transfer after initial debridement and fixation by orthopaedic surgery. The orthoplastic management was implemented on a case-by-case basis based on individual injury characteristics and the surgeon's discretion with no formal starting point. When implemented, the orthoplastic team consisted of an orthopaedic surgeon and microvascular-trained hand surgeons and/or plastic surgeons. In all, 77% (254 of 330) of flaps were performed using this model. We considered perioperative flap complications as any complication (such as infection, hematoma, dehiscence, congestion, or necrosis) resulting in return to the operating room for re-evaluation, correction, or partial debridement of the flap. We defined flap failure as a return to the operating room for debridement of a major portion of the flap or amputation secondary to complete or near-complete loss of flap viability. Of the flap procedures, 12% (40 of 330) were classified as a failure and 14% (46 of 330) experienced complications necessitating return to the operating room. Over the study period, free flaps were not more likely to fail than pedicled flaps (11% versus 13%; p = 0.52) or have complications necessitating additional procedures (14% versus 16%; p = 0.65).

RESULTS

Our multiple linear regression model demonstrated that an increased number of free flaps performed in our institution annually in any given year was associated with a lower likelihood of failure per case (r = -0.17; p = 0.03) and lower likelihood of reoperation for each flap (r = -0.34; p < 0.001), after adjusting for injury severity and team type (orthoplastic or orthopaedic only). We observed a similar relationship for pedicled flaps, with increased annual case volume associated with a decreased risk of flap failure and reoperation per case after adjusting for injury severity and team type (r = -0.21; p = 0.003 and r = -0.22; p < 0.001, respectively). Employment of a collaborative orthoplastic team approach was associated with decreased flap failures (odds ratio 0.4 [95% confidence interval 0.2 to 0.9]; p = 0.02). Factors associated with flap failure included a lower extremity flap (OR 2.7 [95% CI 1.3 to 6.2]; p = 0.01) and use of muscle flaps (OR 2.3 [95% CI 1.1 to 5.3]; p = 0.02).

CONCLUSION

Although prior reports of combat-related extremity trauma have described greater salvage success with the use of pedicled flaps, these reports are biased by institutional inexperience with free tissue transfer, the lack of a coordinated multiservice effort, and severity of injury bias (the most severe injuries often result in free tissue transfer). Our institutional experience, alongside a growing body of literature regarding complex extremity trauma in the civilian setting, suggest a benefit to free tissue coverage to treat complex extremity trauma with adequate practice volume and collaboration. We demonstrated that flap failure and flap-related complications are inversely associated with institutional experience regardless of flap type. Additionally, a collaborative orthoplastic approach was associated with decreased flap failures. However, these results must be interpreted with consideration for potential confounding between the increased case volume coinciding with more frequent collaboration between orthopaedic and plastic surgeons. Given these findings, consideration of an orthoplastic approach at high-volume institutions to address soft tissue coverage in complex extremity trauma may lead to decreased flap failure rates.

LEVEL OF EVIDENCE

Level III, therapeutic study.

IDEO energy-storing orthosis: Effects on lower extremity function and preservation

INTRODUCTION

The Intrepid Dynamic Exoskeletal Orthosis (IDEO) brace is a custom energy-storing orthosis design meant to improve gait, stability, and function after lower extremity injury or limb salvage. Early studies demonstrated the potential for the IDEO to improve functional performance, in conjunction with its paired return to run (RTR) rehabilitation program, compared to other brace types, and an impressively decreased rate of late amputation. The current study aimed to investigate these functional and revision outcomes from our institution to determine which patients may benefit most from IDEO bracing and what factors of the IDEO design and rehabilitation program are most important for improved outcomes after lower extremity trauma and/or loss of function.

METHODS

We performed a retrospective review of all patients treated with a IDEO style brace at a single military lower extremity trauma referral center between May 2003 and November 2017. We reviewed the medical records for initial diagnosis, post-orthotic rehabilitation program, IDEO use characteristics, pain, change in desire for amputation, and whether patient underwent eventual amputation.

RESULTS

We identified 213 patients with 222 lower extremities treated with IDEO brace. Of these, 76 limbs were treated for combat-related injuries. At one year follow-up, use status could not be determined for 37 extremities (16.7%). Of the 185 limbs with use data available, 116 (61.1%) continued regular brace use, and 37 (15.7%) reported intermittent use. Patients diagnosed with footdrop or weakness were more likely to continue use (OR 2.33, p=0.04), while patients with a previous fusion were less likely to continue use (OR 0.45, p=0.049). Undergoing any dedicated therapy increased chances of continued use (OR 3.37, p<0.001). At final follow-up, 16 patients (7.5%) underwent delayed lower extremity amputations following IDEO treatment. Overall, 27.2% of patients who initially desired amputation eventually underwent amputation despite IDEO brace use. Patients who underwent amputation reported higher pain levels (2 versus 5, p<0.001).

DISCUSSION

In select patients, the IDEO may decrease the desire for delayed amputation and permit higher levels of activity; however, its efficacy appears tied to the rehabilitative regimen, pain levels, and initial diagnosis. These findings should guide post-surgical extremity bracing prescriptions and expectations.

Managing Complex Peripheral Nerve Injuries Within the Military Health System: A Multidisciplinary Approach to Treatment, Education, and Research at Walter Reed National Military Medical Center

INTRODUCTION

Peripheral nerve injuries are a leading cause of disability within the Military Health System (MHS) patient population. Many peripheral nerve injuries (PNIs) are amenable to therapeutic intervention but require a timely diagnosis and prompt referral to a specialty center capable of intervention, as functional outcomes are directly related to the duration between injury and intervention. Even when appropriately identified, PNI management in the MHS is often challenged by the lack of an established pathway for care coordination and a limited awareness of available diagnostic and therapeutic resources. To address these potential shortcomings, the Walter Reed National Military Medical Center Peripheral Nerve Program (WRNMMC PNP) in Bethesda, MD, has been established to provide comprehensive, multidisciplinary care to peripheral nerve-injured patients across the MHS. Additionally, the WRNMMC PNP provides graduate medical education training in PNI management for multiple residency and fellowship programs, and it facilitates critical peripheral nerve research to advance knowledge within the field.

MATERIALS AND METHODS

A retrospective review of all patients evaluated by the WRNMMC PNP between December 2015 and April 2019 was conducted in order to identify pertinent patient demographic information, referral patterns, and PNI etiology data.

RESULTS

The WRNMMC PNP evaluated 356 patients consisting of active duty, dependents, retirees, and Veterans Affairs patients during the designated study period. These patients were referred by providers from more than nine different specialties from 78 commands across eight countries. The majority of these patients (222 patients) were referred for traumatic PNI. The WRNMMC PNP has also evaluated and treated patients with PNIs stemming from congenital and compressive etiologies. One hundred and one patients referred during this period were treated with surgery, while the remainder were managed through nonoperative means.

CONCLUSIONS

The WRNMMC PNP facilitates comprehensive, patient-centered care for PNI patients within the MHS. Moreover, the program helps to prepare the next generation of providers for evaluating and treating PNI patients through its involvement with graduate medical education training. It also conducts critical peripheral nerve research and lays the foundation for collaborations with other institutions involved with peripheral nerve research. In the years ahead, the WRNMMC PNP aims to expand its outreach and capabilities within the MHS through more expansive use of telemedicine consultation and the establishment of satellite peripheral nerve clinic sites.

The Incidence of Posterior and Combined AP Shoulder Instability Treatment with Surgical Stabilization Is Higher in an Active Military Population than in the General Population: Findings from the US Naval Academy

BACKGROUND

Anterior instability has consistently been shown to be the most common type of glenohumeral instability. Recent studies have demonstrated a higher percentage of posterior and combined (anterior and posterior) instability than had previously been reported; however, this work has not been replicated recently in a particularly young military population, which may be representative of an especially athletic or high-demand group.

QUESTION/PURPOSE

What proportion of arthroscopic shoulder stabilization procedures are performed to address isolated anterior instability, isolated posterior instability, and combined instability in a young, military population?

METHODS

Between August 2009 and January 2020, two sports medicine fellowship-trained surgeons performed arthroscopic shoulder surgery on 543 patients at a single institution. During that time, the indication to be treated with arthroscopic stabilization surgery was symptomatic glenohumeral instability, as diagnosed by the operative surgeon, that restricted patients from carrying out their military duties. Of those, 82% (443 of 543) could be evaluated in this retrospective study, while 18% (100 of 543) were excluded due to either incomplete data or because the procedure performed was not to address instability. No patient underwent an open stabilization procedure during this period. Of the 443 patients investigated, the mean age was 22 ± 4 years, and 88% (392 of 443 patients) were men. Instability type was characterized as isolated anterior, isolated posterior, or combined (anterior and posterior) according to the physician's diagnosis as listed in the patient's clinical records and operative reports after the particular capsulolabral pathology was identified and addressed.

RESULTS

Isolated anterior instability occurred in 47% of patients (210 of 443). Isolated posterior instability happened in 18% of patients (80 of 443), while combined anteroposterior instability occurred in 35% of patients (153 of 443).

CONCLUSION

Shoulder instability is common in the military population. Although anterior instability occurred most frequently, these findings demonstrate higher proportions of posterior and combined instability than have been previously reported. Surgeons should have a heightened suspicion for posterior and combined anteroposterior labral pathology when performing arthroscopic stabilization procedures to ensure that these instability patterns are recognized and treated appropriately. The current investigation examines a unique cohort of young and active individuals who are at particularly high risk for instability and whose findings may represent a good surrogate for other active populations that a surgeon may encounter.Level of Evidence Level III; therapeutic study.

Synchronous Multifocal Necrotizing Fasciitis: A Case Report

CASE

An immunocompetent 43-year-old man was diagnosed with necrotizing fasciitis of his forearm. Despite receiving appropriate treatment, his clinical condition continued to deteriorate. Further evaluation revealed subsequent proliferation of the infection to multiple noncontiguous areas of the body consistent with a rare condition known as synchronous multifocal necrotizing fasciitis. Prompt identification, followed by serial debridements of all affected areas, ultimately saved the patient's life.

CONCLUSION

This unusual multifocal presentation of necrotizing fasciitis can produce diagnostic uncertainty and delay life-saving treatment. Early recognition, followed by prompt treatment, is paramount for reducing morbidity and mortality associated with this devastating infection.

Low Revision Rates at 10 years for Metal on Metal Hip Implants in a Military Population

INTRODUCTION

Prior to being largely abandoned due to unacceptably high failure rates and the adverse physiologic reactions to metal ions, metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacing (HR) were in widespread use throughout the USA, and the potential benefit of decreased volumetric wear rates made it of particular interest to those who serve a young active population, such as military surgeons. The aim of our study was to determine the revision rate of metal on metal hip implants performed at our military institution and obtain current patient reported outcomes from this cohort.

MATERIALS AND METHODS

We conducted a retrospective review of patients who underwent MoM total hip arthroplasty (THA) or hip resurfacing (HR) at our institution from 2006 to 2012. Revision status and component type were determined, and patients were contacted to obtain current HOOS JR scores.

RESULTS

We identified 103 THAs in 88 patients and 38 HRs in 33 patients, with mean follow up of 10.2 years. Average age at time of surgery was 48 years, and 85% of the patients were male. The mean HOOS JR score in the THA and HR groups were 84.9 ± 17.6 and 75.8 ± 24.9, respectively (p = 0.38), and were not significantly lower in those who were revised. Two THA revisions occurred for metallosis and one for aseptic loosening of the femoral component. One HR revision occurred for breach of the anterior femoral neck, and one occurred for heterotopicossification.

CONCLUSIONS

Revision rates of MoM THA and HR in this young, predominantly male population were 2.9% and 5.3%, respectively, and patients maintained generally good hip-specific outcomes.

Orthopaedic osseointegration: Implantology and future directions

Osseointegration (OI) is the direct anchorage of a metal implant into bone, allowing for the connection of an external prosthesis to the skeleton. Osseointegration was first discovered in the 1960s based on the microscopic analysis of titanium implant placed into host bone. New bone was observed to attach directly to the metal surface. Following clinical investigations into dentistry applications, OI was adapted to treat extremity amputations. These bone anchored implants, which penetrate the skin and soft tissues, eliminate many of the challenges of conventional prosthetic sockets, such as poor fit and suspension, skin breakdown, and pain. Osseointegrated implants show promise to improve prosthesis use, pain, and function for amputees. The successful process of transcutaneous metal integration into host bone requires three synergistic systems: the host bone, the metal implant, and the skin-implant interface. All three systems must be optimized for successful incorporation and longevity of the implant. Osseointegration begins during surgical implantation of the metal components through a complex interplay of cellular mechanisms. While implants can vary in design-including the original screw, press fit implants, and compressive osseointegration-they face common challenges to successful integration and maintenance of fixation within the host bone. Overcoming these challenges requires the understanding of the complex interactions between each element of OI. This review outlines (a) the basic components of OI, (b) the science behind both the bone-implant and the skin-implant interfaces, (c) the current challenges of OI, and (d) future opportunities within the field.

Enhanced angiogenic function in response to fibroblasts from psoriatic arthritis synovium compared to rheumatoid arthritis

Introduction

Angiogenesis is an early event in the pathogenesis of both psoriatic arthritis (PsA) and rheumatoid arthritis (RA); however, there are striking differences in blood vessel morphology and activation between the two arthropathies. The aim of this study was to assess if the PsA and RA joint microenvironments differentially regulate endothelial cell function.

Methods

PsA and RA primary synovial fibroblasts (SFC) were isolated from synovial biopsies, grown to confluence, and supernatants harvested and termed ‘conditioned media’ (CM). Human umbilical vein endothelial cells (HUVEC) were cultured with PsA SFC or RA SFC-CM (20%). HUVEC tube formation, migration, and PBMC adhesion were assessed by matrigel tube formation, wound repair, and PBMC adhesion assays. HUVEC cell surface expression of ICAM, VCAM, and E-Selectin was assessed by flow cytometry. Transcriptome analysis of genes promoting angiogenesis was performed by real-time PCR. Finally, a MSD multiplex angiogenic assay was performed on PsA SFC and RA SFC supernatants.

Results

Macroscopic synovitis and vascularity were similar in PsA and RA patients; however, significant differences in vascular morphological pattern were recorded with tortuous, elongated vessels observed in PsA compared to straight regular branching vessels observed in RA. Transcriptome analysis showed strong upregulation of the pro-angiogenic signature in HUVEC primed with PsA SFC-CM compared to RA SFC-CM and basal control. In parallel, paired PsA SFC-CM significantly induced HUVEC tube formation compared to that of RA SFC-CM. Furthermore, PsA SFC-CM induced HUVEC migration was paralleled by a significant induction in VEGFA, PFKFB3, ICAM-1, and MMP3 mRNA expression. A significant increase in PBMC adhesion and cell surface expression of VCAM-1, ICAM-1, and E-Selectin expression was also demonstrated in PsA SFC-CM-primed HUVEC compared to RA SFC-CM. Finally, VEGF, TSLP, Flt-1, and Tie-2 expression was elevated in PsA SFC-CM compared to RA SFC-CM, with no significant difference in other pro-angiogenic mediators including MIP-3, bFGF, PIGF, and MCP-1.

Conclusion

PsA SFC and RA SFC secreted factors differentially regulate endothelial cell function, with soluble mediators in the PsA joint microenvironment inducing a more pro-angiogenic phenotype compared to the RA.

Altered metabolic pathways regulate synovial inflammation in rheumatoid arthritis

Rheumatoid arthritis is characterized by synovial proliferation, neovascularization and leucocyte extravasation leading to joint destruction and functional disability. The blood vessels in the inflamed synovium are highly dysregulated, resulting in poor delivery of oxygen; this, along with the increased metabolic demand of infiltrating immune cells and inflamed resident cells, results in the lack of key nutrients at the site of inflammation. In these adverse conditions synovial cells must adapt to generate sufficient energy to support their proliferation and activation status, and thus switch their cell metabolism from a resting regulatory state to a highly metabolically active state. This alters redox-sensitive signalling pathways and also results in the accumulation of metabolic intermediates which, in turn, can act as signalling molecules that further exacerbate the inflammatory response. The RA synovium is a multi-cellular tissue, and while many cell types interact to promote the inflammatory response, their metabolic requirements differ. Thus, understanding the complex interplay between hypoxia-induced signalling pathways, metabolic pathways and the inflammatory response will provide better insight into the underlying mechanisms of disease pathogenesis.

A Combined Distal Tibial Turn-up Plasty and Intercalary Calcaneal Osteocutaneous Fillet Flap for Salvage of a Transtibial Amputation: A Case Report

CASE

This case demonstrates the successful attempt at a combined distal tibial turn-up plasty and intercalary calcaneal osteocutaneous fillet flap to increase functional limb length in order to salvage a transtibial amputation following a high-energy blast injury.

CONCLUSION

A transtibial amputation is preferred over more proximal levels of amputation because of the decreased energy expenditure that is required for ambulation. In cases where there is not enough viable tibia to allow for a transtibial level of amputation, combining a calcaneal osteocutaneous fillet flap with a distal tibial turn-up plasty can be utilized to optimize residual limb length for a transtibial amputation.

Inverse agonist activity at the alpha(2A)-adrenergic receptor

Constitutive activation of G protein-coupled receptors (GPCRs) is now well recognized and many classical GPCR antagonists have been found to be inverse agonists. For the alpha(2A)-adrenergic receptor (AR) we determine the relative inverse efficacies of a series of antagonists and utilize the extended ternary complex model to estimate the fraction of constitutively active mutant (CAM) receptors in the active state. Stable Chinese hamster ovary cell lines expressing the porcine alpha(2A)-AR in its wild-type (WT) and constitutively activated (CAM-T373K) form were isolated. Activation of both G(i) and G(s) was enhanced for CAM receptors. cAMP production was suppressed in cells with the CAM alpha(2A)-AR and this suppression was reversed by alpha(2)-adrenergic antagonists with an order of inverse efficacy of rauwolscine > yohimbine > RX821002 > MK912, whereas phentolamine and idazoxan were essentially neutral antagonists. This striking difference in inverse efficacy between idazoxan and RX821002 may account for in vivo pharmacological differences between these two alpha(2)-adrenergic antagonists. Agonist binding affinity to the non-G protein-coupled CAM receptor was 3- to 9-fold higher than to WT, whereas binding of the most efficacious inverse agonists, yohimbine and rauwolscine, was 1.7- and 2.1-fold weaker. Analysis of this difference by the extended ternary complex model indicates that approximately 50% of the CAM alpha(2A)-AR is in the active (R*) state although there is no detectable constitutive activity of the WT receptor in the absence of agonist.

Agonist-directed trafficking of porcine alpha(2A)-adrenergic receptor signaling in Chinese hamster ovary cells: l-isoproterenol selectively activates G(s)

In this study, we investigated the hypothesis of agonist-directed trafficking of receptor signaling for the alpha(2A)-adrenergic receptor (alpha(2A)-AR). alpha(2A)-ARs couple to both G(s) and G(i) to stimulate or inhibit adenylyl cyclase activity. Chinese hamster ovary-K1 cell lines expressing the porcine alpha(2A)-AR at high (alpha(2A)-H) and low (alpha(2A)-L) levels were used to estimate the relative efficacies (R.e.s) of a series of agonists for the G(s) and G(i) pathways. G(s)-mediated responses were measured after pertussis toxin treatment to inactivate G(i) in alpha(2A)-H, whereas G(i) responses were measured in alpha(2A)-L, where G(s) responses were absent. The full agonist UK-14,304 showed a large receptor reserve for G(i) responses in alpha(2A)-H but little receptor reserve for G(s) responses in alpha(2A)-H or for G(i) responses in alpha(2A)-L. With the exception of l-isoproterenol (ISO), all agonists showed similar R.e.s at the alpha(2A)-AR for G(s) and G(i) responses, with rank orders of R.e.s as follows: l-epinephrine = l-norepinephrine = UK-14,304 > p-aminoclonidine > or = BHT-920 > or = BHT-933 > clonidine = p-iodoclonidine > or = xylazine > or = guanabenz. Interestingly, ISO had the highest efficacy at the alpha(2A)-AR for activating G(s) versus G(i) (9-fold higher); however, it had low potency for both. By several criteria, the ISO response was mediated by the alpha(2A)-AR, supporting the hypothesis of agonist-directed trafficking of receptor signaling or agonist-specific G protein selectivity. In contrast, the apparent G(i) pathway selectivity of oxymetazoline appears to be mediated by an endogenous serotonergic receptor. It is intriguing that a classic beta-AR agonist that activates G(s) through beta(2)-ARs also appears to produce a G(s)-selective conformation of the G(i)-coupled alpha(2A)-AR.

G(i) activator region of alpha(2A)-adrenergic receptors: distinct basic residues mediate G(i) versus G(s) activation

The structural determinants of G protein coupling versus activation by G protein-coupled receptors are not well understood. We examine the role of two distinct basic regions in the carboxyl terminal portion of the third intracellular loop of the alpha(2A)-adrenergic receptor to dissect these aspects of function. Changing three arginines to alanines by mutagenesis and stable expression in Chinese hamster ovary-K1 cells impaired the alpha(2)-adrenergic receptor G(s)-mediated stimulation of cyclic AMP (cAMP) accumulation, whereas G(i)-mediated inhibition was normal. When two (B2) or three (B3) basic residues closer to transmembrane span 6 were mutated to alanine, normal ligand binding was observed, but G(i)-mediated inhibition of cAMP accumulation showed 20-fold and 50-fold decreases in agonist potency for the B2 and B3 mutants, respectively. Surprisingly, a normal G(s) response was seen for the B2 mutant, and the B3 mutant showed only a 6-fold decrease in agonist potency. Mutation of both the three alanines and B3 residues to alanines showed a 200-fold decrease in agonist potency for G(i)-mediated inhibition of cAMP accumulation, whereas the G(s) response was nearly completely eliminated. The three basic residues (which include the BB of the BBXXF motif) play a role as G(i) activators rather than in receptor-G protein coupling, because high-affinity agonist binding is intact. Thus, we have identified three basic residues required for activation of G(i) but not required for receptor-G protein coupling. Also, distinct basic residues are required for optimal G(i) and G(s) responses, defining a microspecificity determinant within the carboxyl terminal portion of the third intracellular loop of the alpha(2a) adrenergic receptor.

Cotransfection of second and third intracellular loop fragments inhibit angiotensin AT1a receptor activation of phospholipase C in HEK-293 cells

Peptides from the intracellular regions of G protein-coupled receptors are useful probes of receptor-G protein coupling mechanisms. As a first step toward the genetic delivery of such "G protein inhibitors," we describe inhibition of angiotensin II (AII) receptor responses by expressed fragments of the second and third intracellular loops of the AT1a receptor (AT1a/i2 and AT1a/i3). Transient transfection of human embryonic kidney 293 cells with DNA encoding the rat AT1a receptor resulted in AII-dependent increases of inositol phosphates (maximum 4.5-fold). Cotransfection of AT1a/i2 and AT1a/i3 fragments raised the EC50 for AII stimulation of phospholipase C activity 5-fold (from 0.18 nM to 0.99 nM, n = 12, P < .001) and 3-fold (from 0.38 nM to 1.2 nM, n = 8, P < .002), respectively. The combined effect of AT1a/i2 and AT1a/3 was additive, and transfection of an alpha-1b adrenergic receptor third intracellular loop (alpha1b/i3) fragments also increased the EC50 for AII. Neither AT1a/i1 nor C-terminus (AT1a/Ct) constructs had significant effects on angiotensin responses. These data confirm a role for the second and third intracellular loops in angiotensin receptor responses and show the potential of this approach to blocking multiple phospholipase C-linked receptors.

Modulation of K+ and Ca2+ currents in cultured neurons by an angiotensin II type 1a receptor peptide

Angiotensin II (ANG II) inhibits delayed rectifier K+ current (IK) and stimulates total Ca2+ current (ICa) in neurons cocultured from newborn rat hypothalamus and brain stem, effects mediated via ANG II type 1 (AT1) receptors. Here, we identify potential G protein activator regions of the AT1 receptor responsible for initiating the intracellular changes that lead to alterations in these currents. Intracellular application into cultured neurons of a peptide corresponding to the third cytoplasmic loop of the AT1 receptor (AT1a/i3) mimicked the actions of ANG II on IK and ICa, whereas application of a peptide corresponding to the second cytoplasmic loop (AT1a/i2) did not alter these currents. This modulation of IK and ICa by AT1a/i3 involves intracellular messengers (G alpha q, protein kinase C, and intracellular Ca2+) that are identical to those involved in the modulation of IK and ICa following ANG II activation of AT1 receptors. These data provide functional evidence for a role of the third cytoplasmic loop of the AT1 receptor in G protein coupling and subsequent modulation of ion channel effectors.

Structural requirements for G(o) activation by receptor-derived peptides: activation and modulation domains of the alpha 2-adrenergic receptor i3c region

Synthetic peptides are important tools for understanding the sites and mechanisms of receptor/G protein interactions. We examined the structural determinants of receptor-fragment peptides for G protein binding and activation. A dimer of peptides from the carboxyl-terminal (i3c) and amino-terminal (i3n) regions of the alpha 2A-adrenergic receptor is most potent in stimulating guanine-nucleotide exchange of any peptides studied. Stimulation of GTPase by i3n is partially blocked by pertussis toxin treatment, whereas stimulation by i3c is not, which is consistent with action of i3c at the amino terminus of Gi. Both peptides inhibit adenylyl cyclase in Chinese hamster ovary cell membranes, but only the i3c effect is consistent with a pure Gi stimulation. We also examined the mechanism and defined a minimal structural subset of i3c required for G protein activation. Residues 361-365 from the receptor were essential for GTPase stimulation, whereas determinants in the region 368-373 modulated that activity. A specific role for arginines is defined beyond just their positive charge. Complex effects of modifications of Thr373 suggest a regulatory or conformational role of that residue in the previously defined constitutive activation of the alpha 2-adrenergic receptor [J. Biol. Chem. 268:16483-16487 (1993)]. Thus, our data plus recent mutagenesis results support a role for hydrophobicity in the i3n region and a positively charged/arginine-rich region approximately 15-20 residues from the sixth transmembrane span in G protein activation. In contrast, the immediate perimembrane region of i3c seems to have largely conformational effects in producing constitutive activation of the receptors.

Multisite interactions of receptors and G proteins: enhanced potency of dimeric receptor peptides in modifying G protein function

Synthetic peptides that activate or inhibit G proteins reveal structural determinants of receptor-G protein interactions and show promise as potential therapeutic agents. A cysteine-containing peptide from the carboxyl-terminal part of the third cytoplasmic loop of the alpha 2-adrenergic receptor (peptide Q) uncouples alpha 2-adrenergic receptors from Gi. Peptide Q readily forms disulfide-linked dimers (Qdimer), as detected by high performance liquid chromatography and mass spectrometry. Qdimer is > 100-fold more potent than monomeric Q peptide in inhibiting p-[125I] iodoclonidine binding to the human alpha 2a-adrenergic receptor in platelet membranes and transfected Chinese hamster ovary cells. In addition, Qdimer is 10-20 times more potent than monomeric Q peptide in inhibiting alpha 2 agonist-stimulated GTPase in cell membranes and in directly stimulating G(o)/Gi GTPase in lipid vesicles. The effect of Qdimer is reversible and not mimicked by cystine. Formylation of both tryptophans greatly reduces the potency of the dimer but a single formyl group is well tolerated, indicating an asymmetric interaction of the dimer with Gi in membranes. A mixed dimer of peptides from the amino- and carboxyl-terminal ends of the third cytoplasmic loop of the alpha 2-adrenergic receptor is most potent in all measures of G protein interactions, suggesting that the dimer of Q peptides mimics multiple intracellular portions of the alpha 2-adrenergic receptor with the G protein. These data confirm the importance of multiple receptor regions in G protein activation and suggest a strategy for examining the role of physically separated regions in protein-protein interactions.

Focus group interview with parents of children with medically complex needs: an intimate look at their perceptions and feelings

The purpose of this paper was to identify the needs of parents of children with medically complex needs from their own perception. In order to provide in-depth information, the focus group interview technique was used. Several strong recurrent themes were identified. The most persistent need was for a general organization or framework with which the care providers could operate. Along these same lines, the fragmentation of training, needs and services was consistently stated. A general lack of information in terms of home care and how to plan for the future was identified. Support groups were universally lauded for the invaluable services provided to the care parents.

p-[125I]iodoclonidine is a partial agonist at the alpha 2-adrenergic receptor

The binding properties of p-[125I]iodoclonidine [( 125I]PIC) to human platelet membranes and the functional characteristics of PIC are reported. [125I]PIC bound rapidly and reversibly to platelet membranes, with a first-order association rate constant (kon) at room temperature of 8.0 +/- 2.7 x 10(6) M-1 sec-1 and a dissociation rate constant (koff) of 2.0 +/- 0.8 x 10(-3) sec-1. Scatchard plots of specific [125I]PIC binding (0.1-5 nM) were linear, with a Kd of 1.2 +/- 0.1 nM. [125I]PIC bound to the same number of high affinity sites as the alpha 2-adrenergic receptor (alpha 2-AR) full agonist [3H] bromoxidine (UK14,304), which represented approximately 40% of the sites bound by the antagonist [3H]yohimbine. Guanosine 5'-(beta, gamma-imido)triphosphate greatly reduced the amount of [125I]PIC bound (greater than 80%), without changing the Kd of the residual binding. In competition experiments, the alpha 2-AR-selective ligands yohimbine, bromoxidine, oxymetazoline, clonidine, p-aminoclonidine, (-)-epinephrine, and idazoxan all had Ki values in the low nanomolar range, whereas prazosin, propranolol, and serotonin yielded Ki values in the micromolar range. Epinephrine competition for [125I]PIC binding was stereoselective. Competition for [3H]bromoxidine binding by PIC gave a Ki of 1.0 nM (nH = 1.0), whereas competition for [3H]yohimbine could be resolved into high and low affinity components, with Ki values of 3.7 and 84 nM, respectively. PIC had minimal agonist activity in inhibiting adenylate cyclase in platelet membranes, but it potentiated platelet aggregation induced by ADP with an EC50 of 1.5 microM. PIC also inhibited epinephrine-induced aggregation, with an IC50 of 5.1 microM. Thus, PIC behaves as a partial agonist in a human platelet aggregation assay. [125I]PIC binds to the alpha 2B-AR in NG-10815 cell membranes with a Kd of 0.5 +/- 0.1 nM. [125I]PIC should prove useful in binding assays involving tissues with a low receptor density or in small tissue samples and in studies of cloned and expressed alpha 2-AR.

Immunity to leprosy. IV. Murine T-cell proliferative responses to mycobacteria

The nature of antigens shared between Mycobacterium leprae and other species of mycobacteria has been examined using a murine T-cell proliferation assay. Mice were immunized with different mycobacteria, and lymph node cultures were prepared one week later and challenged with M. leprae antigen. The 13 species of mycobacteria tested as antigens in this assay revealed that several species shared antigens in common with M. leprae as recognized by T-cell responses. C57BL/10J mice and congenic strains exhibit differences in T-cell responsiveness to M. leprae. B10.M and B10.Q mice are high responders and C57BL/10J are low responders, while F1 (C57BL/10J X B10.M) and (C57BL/10J X B10.Q) hybrid progeny are also low responders. These genetic differences were not observed when six other mycobacterial species were used as T-cell antigens. An unexpected finding was that the genetic pattern of T-cell responsiveness to M. marinum was identical to that observed for M. leprae using these strains of mice. Helper T cells may recognize antigenic determinants shared by M. leprae and M. marinum. These antigens may initiate the induction of T-cell responses to these two species of mycobacteria.

Mammalian host- and fluid-mediated mutagenicity assays of captan and streptozotocin in Salmonella typhimurium

The mutagenicity of captan and of streptozotocin was tested in vivo by reversion of hisG46 base-pair substitution histidine auxotrophs of Salmonella typhimurium in the peritoneal cavity or in blood, plasma or urine of rats or mice. Genetic response was determined by the frequency of revertants (quantitative test) or by the number of revertants per plate (semiquantitative test). In quantitative HMA captan gave negative results following 3 hourly 500 mg/kg s.c. doses or 1000 mg/kg oral dose in mice with the hisG46 mutant or 2000 mg/kg oral dose in rats with the hisG46, uvrB (TA1950) mutant. The positive control SZN induced many reversions at 0.5 mg/kg i.p. or 10 or 100 mg/kg oral doses. In semiquantitative in vivo blood or urine assays captan gave negative results after a 250 mg/kg oral dose with hisG46. SZN in the same experiment gave positive results in both semiquantitative and quantitative in vivo blood assays following 1000 mg/kg i.p. or 2000 mg/kg oral doses in the rat with TA1950. Rat blood mixed with captan for 45 min before adding TA1950 cells inactivated 1000 mug captan/ml but not 5000 mg/ml in the semiquantitative test. Corresponding figures in the quantitative test were 500 mu/ml and 1000 mug/ml. Rat plasma inactivated the mutagenicity of about 10 times less captan than rat blood. Human blood inactivated about as much captan as rat blood. The mutagenicity of captan was inactivated more efficiently than of SZN by blood. The results of the experiments suggested that captan's mutagenicity is probably inactivated by glutathione of the erythrocytes. Rat S-9 liver microsomal fraction also strongly decreased captan's mutagenicity in a semiquantitative test with the R factor, uvrB, hisG46 (TA100) mutant.