Engineering growth factor ligands and receptors for therapeutic innovation.

Growth factors signal through engagement and activation of their respective cell surface receptors to choreograph an array of cellular functions, including proliferation, growth, repair, migration, differentiation, and survival. Because of their vital role in determining cell fate and maintaining homeostasis, dysregulation of growth factor pathways leads to the development and/or progression of disease, particularly in the context of cancer. Exciting advances in protein engineering technologies have enabled innovative strategies to redesign naturally occurring growth factor ligands and receptors as targeted therapeutics. We review growth factor protein engineering efforts, including affinity modulation, molecular fusion, the design of decoy receptors, dual specificity constructs, and vaccines. Collectively, these approaches are catapulting next-generation drugs to treat cancer and a host of other conditions.

Protocol for screening and validating antibodies specific to protein phosphorylation sites using a set of yeast biopanning approaches.

Developing antibodies with high specificity against post-translationally modified epitopes remains a challenge. Yeast biopanning is well suited in screening for high-specificity binders. Here, we present a protocol for screening and validating antibodies specific to protein phosphorylation sites using a set of yeast biopanning approaches. We describe steps for screening a yeast surface display library for antibodies and other binders. We then detail procedures for validating the antibodies found by analyzing their specificity through whole-well image analysis in 96-well plates. For complete details on the use and execution of this protocol, please refer to Arbaciauskaite et al.1.

Cricket fast bowling workload patterns as risk factors for tendon, muscle, bone and joint injuries.

OBJECTIVE: To assess workload-related risk factors for injuries to particular tissue types in cricket fast bowlers. DESIGN: 235 fast bowlers who bowled in 14600 player innings over a period of 15 years were followed in a prospective cohort risk factor study to compare overs bowled in each match (including preceding workload patterns) and injury risk in the 3-4 weeks subsequent to the match. Injuries were categorised according to the affected tissue type as either: bone stress, tendon injuries, muscle strain or joint injuries. Workload risk factors were examined using binomial logistic regression multivariate analysis, with a forward stepwise procedure requiring a significance of <0.05. RESULTS: High acute match workload and high previous season workload were risk factors for tendon injuries, but high medium term (3-month workload) was protective. For bone stress injuries, high medium term workload and low career workload were risk factors. For joint injuries, high previous season and career workload were risk factors. There was little relationship between muscle injury and workload although high previous season workload was slightly protective. CONCLUSIONS: The level of injury risk for some tissue types varies in response to preceding fast bowling workload, with tendon injuries most affected by workload patterns. Workload planning may need to be individualised, depending on individual susceptibility to various injury types. This study supports the theory that tendons are at lowest risk with consistent workloads and susceptible to injury with sudden upgrades in workload. Gradual upgrades are recommended, particularly at the start of a bowler's career to reduce the risk of bone stress injury.

Fast bowling match workloads over 5-26 days and risk of injury in the following month.

OBJECTIVES: This study examined whether high match fast bowling workloads in the short to medium term were associated with increased bowling injury rates. DESIGN: Prospective cohort study. METHODS: Over a 15 year period, workload patterns for 235 individual fast bowlers during time periods from 5 to 26 days were examined to consider whether there was an increased injury rate during the month (28 days) subsequent to the workload. RESULTS: Fast bowlers who bowled more than 50 match overs in a 5 day period had a significant increase in injury over the next month compared to bowlers who bowled 50 overs or less RR 1.54 (95% CI 1.04-2.29). For periods ranging from 12 to 26 days, there was no statistically-significant increase in injury over the next month from exceeding thresholds of certain amounts of overs, although bowlers who bowled more than 100 overs in 17 days had a non-significant increase in injury over the next month RR 1.78 (95% CI 0.90-3.50). CONCLUSION: There were no statistically-significant increases in subsequent injury risk for high workloads for periods of 12-26 days, although exceeding 100 overs in 17 days (or less) was associated with higher injury rates. Compression of cricket fixtures is likely to have only a minimal contribution to increased fast bowling injury rates being seen in the T20 era (along with sudden workload increases due to transferring between forms of the game, which has been previously established as a major contributor).

Are Fast-Bowlers Prone to Back Injuries? Prevalence of Lumbar Spine Injuries in Fast-Bowlers: Review of MRI-Based Studies.

BACKGROUND: Fast-bowlers in cricket subject their spines to repetitive stress. OBJECTIVES: The aim of this study was to review the prevalence of lumbar spine injuries among fast-bowlers. MATERIALS AND METHODS: Medline and embase searches were performed. Further, the authors canvassed the reference list of available articles and used other search engines such as Google Scholar to identify a total of nine studies. RESULTS: The prevalence of lumbar disc degeneration in fast-bowlers ranges from 21-65% with an incidence rate of 15% per year, and the prevalence of lumbar spine bony abnormalities ranges from 24-81%. Factors associated with lumbar spine injury in fast-bowlers are classified into un-modifiable (age) and modifiable (more intense bowling workload and mixed-bowling technique). CONCLUSIONS: Fast-bowlers have a high prevalence of lumbar spine injuries. Appropriate interventions, such as educational sessions, may be able to modify risk factors such as bowling workload and bowling technique and thus reduce injury prevalence.

Tendon injuries--practice tips for GPs.

BACKGROUND: Tendon injuries are common, generally degenerative in nature, and can cause significant morbidity if not appropriately managed. OBJECTIVE: This article outlines some key principles about tendon injuries with a particular focus on diagnosis and management. DISCUSSION: Diagnosis is made primarily on history and examination with imaging prescribed for unusual or recalcitrant cases. Examination elicits local tendon tenderness, pain with passive stretch, and pain with active contraction or specific provocative tests. Treatment involves pain control and musculotendinous rehabilitation. Pain control may include the application of ice, bracing and medications. Exercise rehabilitation is the mainstay of treatment for chronic tendon injuries and must include stretch and strengthening exercises. Generally, strengthening exercises for tendon injuries are eccentric in nature and should be performed relatively pain-free. Injectable modalities may be used as an adjunct to decrease pain and facilitate exercise rehabilitation, but should not be used in isolation.

Platelet-rich plasma treatment for ligament and tendon injuries.

Platelet-rich plasma (PRP) is derived from centrifuging whole blood, has a platelet concentration higher than that of the whole blood, is the cellular component of plasma that settles after centrifugation, and contains numerous growth factors. There is increasing interest in the sports medicine and athletic community about providing endogenous growth factors directly to the injury site, using autologous blood products such as PRP, to potentially facilitate healing and earlier return to sport after musculoskeletal injury. Despite this interest, and apparent widespread use, there is a lack of high-level evidence regarding randomized clinical trials assessing the efficacy of PRP in treating ligament and tendon injuries. Basic science and animal studies and small case series reports on PRP injections for ligament or tendon injuries, but few randomized controlled clinical trials have assessed the efficacy of PRP injections and none have demonstrated scientific evidence of efficacy. Scientific studies should be performed to assess clinical indications, efficacy, and safety of PRP, and this will require appropriately powered randomized controlled trials with adequate and validated clinical and functional outcome measures and sound statistical analysis. Other aspects of PRP use that need to be determined are (1) volume of injection/application, (2) most effective preparation, (3) buffering/activation, (4) injection technique (1 depot vs multiple depots), (5) timing of injection to injury, (6) single application versus series of injections, and (7) the most effective rehabilitation protocol to use after PRP injection. With all proposed treatments, the doctor and the patient should weigh up potential benefits of treatment, potential risks, and costs. Based on the limited publications to date and theoretical considerations, the potential risks involved with PRP are fortunately very low. However, benefits remain unproven to date, particularly when comparing PRP with other injections for ligament and tendon injuries.

Five-year prospective comparison study of topical glyceryl trinitrate treatment of chronic lateral epicondylosis at the elbow.

BACKGROUND: Topical glyceryl trinitrate (GTN) treatment has previously demonstrated short-term efficacy in the treatment of lateral epicondylosis. No long-term follow-up has been performed. HYPOTHESIS: Benefits from topical GTN persist 5 years after the cessation of therapy. STUDY DESIGN: A prospective comparative study. METHODS: A follow-up study of 58 patients treated with 6 months of topical GTN or placebo, combined with a tendon rehabilitation programme, was performed 5 years after discontinuation of therapy. Assessment included patient-rated pain scores, clinically assessed lateral epicondylar and proximal common extensor tendon tenderness, hand-held dynamometer measurement of resisted third finger metacarpophalangeal extension with a fully extended elbow (Maudsley's test) and wrist extensor tendon mean peak force using a modified chair pick-up test (the Orthopaedic Research Institute-tennis elbow testing system). RESULTS: Patients in both the GTN group and those in the placebo group had significant improvements in symptoms, clinical signs and provocative functional tests compared with baseline week 0 measures. GTN did not offer any additional clinical benefit over a standard tendon rehabilitation programme at 5 years. CONCLUSION: While GTN appears to offer short-term benefits up to 6 months in the treatment of lateral epicondylosis, at 5 years there does not appear to be significant clinical benefits when compared with patients undertaking a standard tendon rehabilitation programme alone. This is in contrast to findings of continued benefits at long-term follow-up described in the literature for patients with Achilles tendinopathy treated with GTN.

Epidemiology of hepatitis B among professional male athletes in Qatar.

OBJECTIVE: To assess the Hepatitis B status of sportsmen competing in Qatar and to evaluate the risk of transmission. METHODS: In a cross-sectional study design, serological analysis was carried out on 780 sportsmen who attended the Qatar Orthopaedic and Sports Medicine Hospital, Doha Qatar, between March 2008 and February 2009 for a pre-participation screening. RESULTS: Hepatitis B infection prevalence of 2.2% and a lack of immunity in 53.3%. Highest rates of infection were observed in non-Qatari nationals, particularly those of African origin. There was no clear trend with age and immunity level, but cycling was found to have significantly higher rates of Hepatitis B infection. There was no difference in infection rates between contact and non-contact sports. CONCLUSION: The risk of Hepatitis B transmission in football was assessed at one transmission in 12.5 million football matches, but the high rate of non-immunity suggests that sportsmen competing in Qatar are at elevated risk of Hepatitis B infection should they be exposed. This imbalance of infection and immunity rates requires further investigation and urgent redress.

Three-year followup study of topical glyceryl trinitrate treatment of chronic noninsertional Achilles tendinopathy.

BACKGROUND: Topical glyceryl trinitrate treatment has demonstrated short-term efficacy in chronic noninsertional Achilles tendinopathy. No long-term followup is reported. We aimed to assess if the demonstrated efficacy of this treatment persisted 3 years after discontinuation of therapy. METHODS: A follow-up study of 52 patients (68 tendons) treated with 6 months of glyceryl trinitrate therapy or placebo was performed 3 years after cessation of therapy. Assessment included pain scores, return to previous activity, the Victorian Institute of Sport Achilles tendon scale (VISA-A), asymptomatic patient outcomes, clinical assessment of tendon tenderness, and functional hop test. RESULTS: Patients treated with topical glyceryl trinitrate had significantly less Achilles tendon tenderness (p = 0.03), and improved VISA-A scores (p = 0.04) than those in the placebo group; 88% (28 of 32 tendons) of patients were completely asymptomatic at 3 years (VISA-A score of 100) compared to 67% (24 of 36 tendons) of patients treated with rehabilitation alone (p = 0.03 with Chi square analysis). Other outcome measures showed nonsignificant trends towards improvement in the glyceryl trinitrate group (pain scores p = 0.07, functional hop test p = 0.07, and return to sport p = 0.16). The mean estimated effect size for all outcome measures was 0.21. CONCLUSIONS: Topical glyceryl trinitrate treatment has demonstrated efficacy in treating chronic noninsertional Achilles tendinopathy, and the treatment benefits continue at 3 years. Significant differences in asymptomatic patient outcomes for the glyceryl trinitrate group continue at 3 years, and this is confirmed by the effect size estimate. This suggests that the mechanism of action of topical glyceryl trinitrate on chronic tendinopathies is more than an analgesic effect.

The use of therapeutic medications for soft-tissue injuries in sports medicine.

The use of non-steroidal anti-inflammatory drugs (NSAIDs) to treat most muscle, ligament and tendon injuries should be reassessed. They have, at best, a mild effect on relieving symptoms and are potentially deleterious to tissue healing. Soft-tissue injury associated with definite inflammatory conditions such as bursitis or synovitis or involving nerve impingement does warrant short-term treatment with NSAIDs. Paracetamol has similar efficacy to NSAIDs in soft-tissue injury, is cheaper, and has a lower side-effect profile. It is the analgesic of choice for most soft-tissue injury. Cyclo-oxygenase-2 (COX-2) inhibitors should not be used to treat soft-tissue injuries unless impingement is a major feature and non-selective NSAIDs are contraindicated (eg, coexisting gastric disorder), and the patient is not at cardiovascular risk. Corticosteroid injections for tendon injuries may achieve a mild to moderate reduction in pain for up to 6 weeks. However, they do not promote tendon healing, so should generally be used only when healing is not a critical goal. Promising new therapeutic treatments for soft-tissue injuries include topical glyceryl trinitrate, aprotinin injections, and prolotherapy.

Topical glyceryl trinitrate application in the treatment of chronic supraspinatus tendinopathy: a randomized, double-blinded, placebo-controlled clinical trial.

BACKGROUND: Topical glyceryl trinitrate therapy has previously demonstrated short-term pain reduction in patients with supraspinatus tendinopathy. HYPOTHESIS: Topical glyceryl trinitrate improves outcome measures in patients with supraspinatus tendinopathy. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Fifty-three patients (57 shoulders) were recruited, and the authors completed a prospective, randomized, double-blinded, placebo-controlled clinical trial of continuous topical glyceryl trinitrate treatment (1.25 mg/24-h glyceryl trinitrate). RESULTS: The glyceryl trinitrate group had significantly reduced shoulder pain with activity, at night, and at rest at week 24 (P = .03); reduced internal rotation impingement at week 24 (P = .02); increased range of motion in abduction and internal rotation at week 24 (P = .04); and increased force at weeks 12 and 24 with supraspinatus muscle testing (P = .001), external rotation (P = .04), internal rotation (P = .01), adduction (P = .04), and subscapularis pushoff (P = .01). Forty-six percent of patients on glyceryl trinitrate patches were asymptomatic with activities of daily living at 6 months compared with 24% of patients with tendon rehabilitation alone (P = .007, chi(2) analysis). Mean effect size for all outcome measures was 0.26. DISCUSSION: Topical glyceryl trinitrate treatment significantly improved pain scores, range of motion, internal rotation impingement, muscular force, and patient outcomes in patients with supraspinatus tendinopathy. Topical glyceryl trinitrate should be included as part of nonsurgical management of chronic tendinopathies.

Identification of prognostic indicators for patient outcomes in extensor tendinopathy at the elbow.

Extensor tendinopathy is a degenerative overuse condition involving the common extensor tendon at the lateral humeral epicondyle. The diagnosis and management of this condition are clinically based. Our aims were to determine if through patient history and clinical examination we could ascertain prognostic factors affecting time to symptom resolution in extensor tendinopathy. Symptomatic patients (N=28) had a thorough history and examination, and rehabilitation monitored regularly for 6 months. Patient outcomes at 6 months were then correlated with specific factors on initial presentation. Factors implicated as having prognostic significance regarding patient outcomes were a current history of manual work (P=0.04, effect size -0.29), and a current history of weekly participation in racquet sports (P=0.01, effect size -0.41). These individual factors had a significantly decreased chance of symptom resolution at the 6-month stage, and when combined had an effect size of -0.6 (P=0.001). Negative patient outcomes may be related to current high and repetitive levels of tendon stress, and rest from recreational and occupational use of wrist extensor tendons may be necessary to enhance the chances of complete symptom resolution. Enforced rest has monetary and quality-of-life implications, but is probably preferable to an incomplete recovery and prolonged tendon pain and dysfunction.

Topical glyceryl trinitrate treatment of chronic noninsertional achilles tendinopathy. A randomized, double-blind, placebo-controlled trial.

BACKGROUND: Noninsertional Achilles tendinopathy is a degenerative overuse disorder. No method has been universally successful in treating this condition. Topically applied nitric oxide has been shown, in animal models, to be effective for the treatment of fractures and cutaneous wounds through mechanisms that may include stimulation of collagen synthesis in fibroblasts. The goal of the present study was to determine if topical glyceryl trinitrate improves clinical outcome measures in patients with Achilles tendinopathy. METHODS: A prospective, randomized, double-blind, placebo-controlled trial involving a total of sixty-five patients (eighty-four Achilles tendons) was performed to compare continuous application of topical glyceryl trinitrate (at a dosage of 1.25 mg per twenty-four hours) with rehabilitation alone for the treatment of noninsertional Achilles tendinopathy. RESULTS: Compared with the control group, the glyceryl trinitrate group showed reduced pain with activity at twelve weeks (p = 0.02) and twenty-four weeks (p = 0.03), reduced night pain at twelve weeks (p = 0.04), reduced tenderness at twelve weeks (p = 0.02), decreased pain scores after the hop test at twenty-four weeks (p = 0.005), and increased ankle plantar flexor mean total work compared with the baseline level at twenty-four weeks (p = 0.04). Twenty-eight (78%) of thirty-six tendons in the glyceryl trinitrate group were asymptomatic with activities of daily living at six months, compared with twenty (49%) of forty-one tendons in the placebo group (p = 0.001, chi-square analysis). The mean effect size for all outcome measures was 0.14. CONCLUSIONS: Topical glyceryl trinitrate significantly reduced pain with activity and at night, improved functional measures, and improved outcomes in patients with Achilles tendinopathy.

The Orthopaedic Research Institute-Tennis Elbow Testing System: A modified chair pick-up test-interrater and intrarater reliability testing and validity for monitoring lateral epicondylosis.

Lateral epicondylosis is a degenerative overuse tendinopathy involving the extensor tendons of the forearm, predominantly the extensor carpi radialis brevis, in the region of the lateral epicondyle of the elbow. The Orthopaedic Research Institute-Tennis Elbow Testing System (ORI-TETS) is designed to record objective measurements of force generated with a simulated chair pick-up test. Interrater reliability of the ORI-TETS was excellent, with high intraclass correlation coefficients (ICCs) for right arm mean peak force of 0.93, left arm mean peak force of 0.84, right arm mean total force of 0.93, and left arm mean total force of 0.86. The ORI-TETS also demonstrated excellent intrarater reliability, with ICCs ranging from 0.9 to 0.97. The relative technical error of the ORI-TETS for all measurements ranged from 5.8% to 7.2%. Testing patients with lateral epicondylosis (N = 16) and comparing analog pain scores with ORI-TETS testing demonstrated a strong negative relationship between the two parameters (Spearman rho, -0.87 to -1.0). Thus, the ORI-TETS is a reliable and reproducible testing system for the forearm extensors. The testing system is inexpensive, takes 5 minutes to perform, and demonstrates good predictive value for objectively assessing patients with lateral epicondylosis. This system could be used for routine clinical monitoring of patients with lateral epicondylosis.

Topical nitric oxide application in the treatment of chronic extensor tendinosis at the elbow: a randomized, double-blinded, placebo-controlled clinical trial.

BACKGROUND: Extensor tendinosis ("tennis elbow") is a degenerative overuse tendinopathy of the wrist extensors at their attachment to the lateral humeral epicondyle. No treatment has been universally successful. Topical application of nitric oxide has been used effectively to treat fractures and cutaneous wounds in animal models, presumably by stimulation of collagen synthesis in fibroblasts. PURPOSE: To determine whether topical nitric oxide can improve outcome of patients with extensor tendinosis. STUDY DESIGN: Prospective, randomized, double-blinded clinical trial. METHODS: Eighty-six patients with extensor tendinosis were randomized into two equal groups; both were instructed to perform a standard tendon rehabilitation program. One group received an active glyceryl trinitrate transdermal patch, and the other group received a placebo patch. RESULTS: Patients in the glyceryl trinitrate group had significantly reduced elbow pain with activity at 2 weeks, reduced epicondylar tenderness at 6 and 12 weeks, and an increase in wrist extensor mean peak force and total work at 24 weeks. At 6 months, 81% of treated patients were asymptomatic during activities of daily living, compared with 60% of patients who had tendon rehabilitation alone. CONCLUSIONS: Application of topical nitric oxide improved early pain with activity, late functional measures, and outcomes of patients with extensor tendinosis.

The Orthopaedic Research Institute-Ankle Strength Testing System: inter-rater and intra-rater reliability testing.

Achilles tendinosis is a degenerative overuse tendinopathy involving the primary ankle plantarflexors, namely the soleus and gastrocnemius muscles forming the tendo Achilles. The Orthopaedic Research Institute-Ankle Strength Testing System (ORI-ASTS) was designed to record objective measurements of force generated with a resisted ankle plantarflexion test. Testing normal subjects (n=6) was used to establish the reliability of the ORI-ASTS for measuring ankle plantarflexion force. Testing patients with Achilles tendonitis (n=5) over time and comparing Achilles tendon analogue pain scores to ankle plantarflexion force measurements was used to assess the validity of the ORI-ASTS for monitoring progression of Achilles tendinopathy. Inter-rater reliability of the ORI-ASTS with normal subjects was excellent, with single measure intraclass correlation coefficients (ICC) for right mean peak force of 0.92, left mean peak force of 0.96, right mean total force of 0.89, left mean total force of 0.91. The ORI-ASTS also had excellent intra-rater reliability for normal subjects with the following single measure ICC scores: right mean force 0.96, left mean force 0.92, right mean total force 0.97, left mean total force 0.92. The relative technical errors of measurement were calculated from these results, and ranged from 1.0% to 2.7%. Testing patients with Achilles tendinosis (n=5), and comparing analogue activity pain scores to ORI-ASTS testing demonstrated a strong negative relationship between the two parameters (Spearman Rho -0.87 to -1.0, Kendall tau b -0.82 to -1.0). The relationship was statistically significant at the p=0.01 level for two of the five patients. The ORI-ASTS shows excellent reliability for testing ankle plantarflexor force, and appears valid for objectively assessing and monitoring patients with Achilles tendinosis.