Clinical and radiologic outcomes in patients with meniscal root tears

BACKGROUND

Meniscal root tears can lead to early knee osteoarthritis and pain. This study aimed (1) to compare clinical and radiological outcomes between patients who underwent arthroscopic meniscal root repair after meniscal root tears and those who received non-surgical treatment, and (2) to identify whether baseline MRI findings could be potential predictors for future treatment strategies.

METHODS

Patients with meniscal root tears were identified from our picture archiving and communication system from 2016 to 2020. Two radiologists reviewed radiographs and MRI studies using Kellgren-Lawrence (KL) grading and a modified Whole Organ MRI Scoring (WORMS) at baseline and follow-up. The median (interquartile range [IQR]) of follow-up radiographs and MRI studies were 134 (44-443) days and 502 (260-1176) days, respectively. MR images were assessed for root tear-related findings. Pain scores using visual analogue scale (VAS) and management strategies (non-surgical vs. arthroscopic root repair) were also collected. Chi-squared tests and independent t-tests were used to assess differences regarding clinical and imaging variables between treatment groups. Logistic regression analyses were performed to evaluate the associations between baseline MRI findings and each future treatment.

RESULTS

Ninety patients were included. VAS pain scores were significantly (p < 0.01) lower after arthroscopic repair compared to conservative treatment (1.27±0.38vs.4±0.52) at the last follow-up visit with median (IQR) of 325 (180-1391) days. Increased meniscal extrusion (mm) was associated with higher odds of receiving non-surgical treatment (OR = 1.65, 95%CI 1.02-2.69, p = 0.04). The odds of having arthroscopic repair increased by 19% for every 1 mm increase in the distance of the tear from the root attachment (OR = 1.19, 95% CI: 1.05-1.36, p < 0.01). The odds of undergoing arthroscopic repair were reduced by 49% for every 1 mm increase in the extent of meniscal extrusion (OR = 0.51, 95% CI: 0.29-0.91, p = 0.02) as observed in the baseline MRI.

CONCLUSIONS

Patients who underwent arthroscopic repair had lower pain scores than patients with conservative treatment in the follow-up. Distance of the torn meniscus to the root attachment and the extent of meniscal extrusion were significant predictors for arthroscopic repair in the next three weeks (time from the baseline MRI to the surgery date).

How to Recognize, Correct, and Avoid Intraoperative Complications During Anterior Cruciate Ligament Reconstructions

Technical complications are a leading cause of graft failure following anterior cruciate ligament reconstructions. Complications can occur during any phase of the procedure, from graft harvesting to tunnel preparation to graft fixation. Predicting potential causes of technical difficulty and developing strategies to avoid potential pitfalls can limit the number of intraoperative complications. If adverse events do occur intraoperatively, prompt recognition and treatment can lead to favorable outcomes. It is important to discuss strategies to understand potential complications and develop tactics to avoid and correct adverse events that can occur during anterior cruciate ligament reconstruction.

Augmented baseplates in reverse shoulder arthroplasty: a systematic review of outcomes and complications

Background

Glenoid wear secondary to primary osteoarthritis or rotator cuff arthropathy is an obstacle commonly encountered by surgeons performing reverse shoulder arthroplasty, with numerous techniques devised to address this finding. The most recent of such techniques is the introduction of augmented glenoid baseplates to fill these glenoid defects. The objectives of this systematic review are to analyze clinical outcomes of augmented baseplates in patients with glenoid wear, including pain, range of motion, patient-reported functional scores, radiographic outcome measures, complication rates, and revision rates.

Methods

Three online databases (Ovid Medline, EMBASE, Pubmed) were searched for studies publishing clinical and functional outcomes of augmented baseplates in primary reverse shoulder arthroplasty. Findings were aggregated and frequency-weighted means of these variables were calculated when applicable.

Results

Seven studies comprising 810 patients were included in this review. The mean patient age was 72.1 ± 8.1 years with an average follow-up time of 41.4 months. Frequency-weighted means of improvement in forward elevation, abduction, and active external rotation were 53°, 47°, and 19°, respectively. Patients experienced American Shoulder and Elbow Surgeons, Simple Shoulder Test, and Constant score improvements of 45.9, 5.9, and 33.7, respectively. Pooled complicated rate was 6.4%, with 10 cases of baseplate loosening and 3 cases of instability. Five (0.6%) patients required reoperation. Subdividing among augment type (posterior, superior, posterosuperior), there were no apparent differences in outcomes or complication rates between directional augments.

Conclusion

This systematic review demonstrates that augmented baseplates for reverse shoulder arthroplasty provide positive outcomes both clinically and functionally at early follow-up. Complications are within an acceptable range for primary reverse shoulder arthroplasty, with a low rate of revision. Augmented baseplates should serve as a viable option for surgeons seeking to address glenoid wear during reverse shoulder arthroplasty.

Complications and re-operations after extensor mechanism repair surgery in a large cross-sectional cohort: females and tobacco-users at highest risk for adverse outcomes

PURPOSE

There is little information on patients most at risk for poor outcomes following surgical repair of extensor mechanism tendon injuries. The purpose of this study is to provide an epidemiological overview of patients undergoing patellar or quadriceps tendon repair and to assess the incidence of postoperative complications, readmissions, and revision repairs among this population.

METHODS

Retrospective data were obtained using the PearlDiver database for patellar tendon repair and quadriceps tendon repair patients between 2010 and 2020. Baseline demographics, incidences of 90-day readmissions and postoperative complications, and reoperation rates were collected for each group. Multivariate logistic regression was performed to assess the predictive power of each demographic variable on the incidence of postoperative complications and reoperations.

RESULTS

In total, 1543 patients underwent patellar tendon repair and 601 underwent quadriceps tendon repair. Complications within 90-days were observed in 33.7% of patients with patellar tendon repair and 39.2% of patients with quadriceps tendon repair. Reoperation rates were 4.2% and 4.8% for patellar tendon repair and quadriceps tendon repair, respectively. Females in both patellar tendon repair and quadriceps tendon repair groups were at significantly higher risk for post-operative complications (patellar tendon repair OR 3.0, 95% CI 2.4-3.7; quadriceps tendon repair OR 2.9, 95% CI 1.9-4.6; p < 0.001 for both). Older age (p < 0.001), female gender (p < 0.001), CCI (p < 0.001), tobacco use (p < 0.001), and obesity (p < 0.01) were all predictors of experiencing at least one complication following patellar tendon repair. For quadriceps tendon repair, female gender (p < 0.001) and CCI (p < 0.001) were the strongest predictors of experiencing at least one complication, while older age, tobacco use, and obesity (p < 0.05 for all) were also significant independent predictors.

CONCLUSION

Patellar tendon repair patients are younger on average than quadriceps tendon repair patients. Although females are less likely to sustain extensor mechanism ruptures compared to males, females are significantly more likely to have at least one complication after quadriceps or patellar tendon repair. These findings may be used by surgeons, patients, and payors to understand who is most at risk for adverse outcomes following extensor mechanism repair surgery, resulting in earlier intervention and counseling to reduce the likelihood of a poor outcome following extensor mechanism repair surgery.

LEVEL OF EVIDENCE

Level III.

Bone Bruise Patterns Associated With Pediatric and Adult Anterior Cruciate Ligament Tears Are Different

Purpose

To describe differences in radiographic and magnetic resonance imaging (MRI) findings between adult and pediatric patients with known primary anterior cruciate ligament (ACL) injuries.

Methods

We performed a retrospective analysis of surgical patients with a history of ACL tears treated at our institution over a 7-year period. Patients were divided into 2 cohorts based on age (≤15 years and ≥21 years). Patients' radiographs and MRI studies were used to compare features including fracture incidence, bone bruise pattern, associated ligamentous injuries, and meniscal injuries between the 2 groups. Proportions of associated findings were analyzed using the 2-proportion z test.

Results

Within our cohorts of 52 sex-matched pediatric and adult patients, we found that pediatric patients were more likely to have radiographic evidence of fracture (P = .001) and MRI evidence of lateral femoral condylar bone bruising (P = .012). Adult patients had higher rates of medial femoral condylar bruising (P = .016) and medial proximal tibial bruising (P = .005), as well as popliteal fibular ligament injuries (P = .037), identified on MRI.

Conclusions

In this study, we identified differences in bone bruise patterns between pediatric and adult patients with primary ACL tears. Pediatric patients were more likely to have radiographic evidence of fracture and MRI evidence of lateral femoral condylar bone bruising. Adult patients were more likely to show medial femoral condylar and medial proximal tibial bone bruising, as well as popliteal fibular ligament injuries.

Level of Evidence

Level IV, prognostic case series.

Classifying shoulder implants in X-ray images using deep learning

Total Shoulder Arthroplasty (TSA) is a type of surgery in which the damaged ball of the shoulder is replaced with a prosthesis. Many years later, this prosthesis may be in need of servicing or replacement. In some situations, such as when the patient has changed his country of residence, the model and the manufacturer of the prosthesis may be unknown to the patient and primary doctor. Correct identification of the implant's model prior to surgery is required for selecting the correct equipment and procedure. We present a novel way to automatically classify shoulder implants in X-ray images. We employ deep learning models and compare their performance to alternative classifiers, such as random forests and gradient boosting. We find that deep convolutional neural networks outperform other classifiers significantly if and only if out-of-domain data such as ImageNet is used to pre-train the models. In a data set containing X-ray images of shoulder implants from 4 manufacturers and 16 different models, deep learning is able to identify the correct manufacturer with an accuracy of approximately 80% in 10-fold cross validation, while other classifiers achieve an accuracy of 56% or less. We believe that this approach will be a useful tool in clinical practice, and is likely applicable to other kinds of prostheses.

Navigating the Research in Rotator Cuff Disease: An Evidence-Based Approach to Improved Patient Outcomes

Rotator cuff tears are prevalent injuries, yet their management and identifying patients who will benefit from surgical intervention are controversial topics. Population studies demonstrate high rates of asymptomatic tears that, with time, show a general progression of the pathologic state. However, not all tears are or will become symptomatic or require surgical intervention. Surgeons should be aware of the natural history of rotator cuff tears and be able to identify injuries at risk of progression or causing symptoms, be able to determine the cellular level of tear characteristics and healing, understand current management strategies and outcomes, and be familiar with future directions for therapies and research.

Evaluating meniscus allograft transplant using a cost-effectiveness threshold analysis

BACKGROUND

It is unknown if meniscal allograft transplant (MAT) delays progression of osteoarthritis (OA). Cost-effectiveness threshold analysis can demonstrate the necessary delay in OA progression required by MAT to be considered cost-effective compared to non-operative management. The purpose of this study is to identify the efficacy MAT requires in delaying progression to OA in previously meniscectomized knees in order to be considered cost-effective compared to non-operative treatment. A secondary goal is to demonstrate the influence of age and BMI on the required efficacy of MAT for cost-effectiveness.

METHODS

A Markov model was developed to evaluate the cost-effectiveness of MAT compared to non-operative management for patients with prior meniscectomy. Input parameters were identified in existing literature. Cost was derived from literature and The PearlDiver Patient Records Database. The required rate of OA progression was compared across treatment modalities to determine how effective MAT is required to be cost-effective.

RESULTS

MAT needs to be 31% more effective in delaying OA compared to non-operative interventions in order to be cost-effective. MAT is most cost-effective in 20-29 year-old patients, requiring a 25% greater efficacy in delaying OA. Obesity (BMI 30-35) makes MAT less cost-effective when compared to non-obese patients; however, the difference in required efficacy in delaying OA among obese patient when compared to non-operative management is approximately 10%.

CONCLUSIONS

MAT needs to be approximately one-third more effective in delaying OA in previously meniscectomized knees to be considered cost-effective. Younger, non-obese patients have the lowest required efficacy of MAT to be cost-effective.

Role of pulsed electromagnetic fields (PEMF) on tenocytes and myoblasts-potential application for treating rotator cuff tears

The post-surgery integrity of the tendons and muscle quality are the two major factors in success of rotator cuff (RC) repair. Though surgical techniques for rotator cuff repair have significantly improved in the past two decades, there are no effective treatments to improve tendon-to-bone healing and muscle quality after repair at this point in time. Pulsed electromagnetic fields (PEMF) have previously been used for promoting fracture healing. Previous studies have shown that PEMF has a positive role in promoting osteoblast precursors proliferation and differentiation. However, PEMFs effect on tenocytes and muscle cells has not been determined fully yet. The purpose of this study is to define the role of a commercially available PEMF on tenocytes and myoblasts growth and differentiation in vitro. Human rotator cuff tenocytes and C2C12 murine myoblasts were cultured and treated with PEMF for 2 weeks under regular and inflammatory conditions. Our results showed that 2 weeks treatment of PEMF enhanced gene expressions of growth factors in human rotator cuff tenocytes under inflammatory conditions. PEMF significantly enhanced C2C12 myotube formation under normal and inflammatory conditions. Results from this study suggest that PEMF has a positive role in promoting tenocyte gene expression and myoblast differentiation. Therefore, PEMF may potentially serve as a non-operative treatment to improve clinical incomes rotator cuff tendon repairs. Results © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:956-964, 2017.

Intra- and interobserver agreement in the classification and treatment of distal third clavicle fractures

BACKGROUND

In treatment of distal third clavicle fractures, the Neer classification system, based on the location of the fracture in relation to the coracoclavicular ligaments, has traditionally been used to determine fracture pattern stability.

PURPOSE

To determine the intra- and interobserver reliability in the classification of distal third clavicle fractures via standard plain radiographs and the intra- and interobserver agreement in the preferred treatment of these fractures.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 3.

METHODS

Thirty radiographs of distal clavicle fractures were randomly selected from patients treated for distal clavicle fractures between 2006 and 2011. The radiographs were distributed to 22 shoulder/sports medicine fellowship-trained orthopaedic surgeons. Fourteen surgeons responded and took part in the study. The evaluators were asked to measure the size of the distal fragment, classify the fracture pattern as stable or unstable, assign the Neer classification, and recommend operative versus nonoperative treatment. The radiographs were reordered and redistributed 3 months later. Inter- and intrarater agreement was determined for the distal fragment size, stability of the fracture, Neer classification, and decision to operate. Single variable logistic regression was performed to determine what factors could most accurately predict the decision for surgery.

RESULTS

Interrater agreement was fair for distal fragment size, moderate for stability, fair for Neer classification, slight for type IIB and III fractures, and moderate for treatment approach. Intrarater agreement was moderate for distal fragment size categories (κ = 0.50, P < .001) and Neer classification (κ = 0.42, P < .001) and substantial for stable fracture (κ = 0.65, P < .001) and decision to operate (κ = 0.65, P < .001). Fracture stability was the best predictor of treatment, with 89% accuracy (P < .001).

CONCLUSION

Fracture stability determination and the decision to operate had the highest interobserver agreement. Fracture stability was the key determinant of treatment, rather than the Neer classification system or the size of the distal fragment.

A biomechanical comparison of superior and anterior positioning of precontoured plates for midshaft clavicle fractures

With recent studies suggesting improved outcomes in displaced midshaft clavicle fractures treated with open reduction and internal fixation, debate has increased over the preferred plate positioning. Biomechanical studies have yielded conflicting results and have been limited by the almost exclusive use of a simple transverse fracture model. We conducted a study to biomechanically compare superior and anterior plate positioning for clinically relevant midshaft clavicle fracture patterns. Oblique, bending wedge, and complex comminuted fracture patterns were created sequentially in 12 synthetic clavicles. Half were plated with precontoured superior plates and half with precontoured anterior plates. Constructs were loaded in axial compression, torsion, and cantilever bending to determine construct stiffness for comparison of plate positioning. Results showed that, for all fracture patterns, more construct stiffness was achieved in axial compression and torsion (except for the oblique fracture pattern in clockwise torsion) with a superior plate, whereas more construct stiffness was achieved in cantilever bending with an anterior plate. Oblique fractures were significantly stiffer than bending wedge and complex comminuted fractures. Given the unknown relative importance of loading conditions, absolute recommendations for either superior or anterior plates cannot be made.

Evaluating rotational kinematics of the knee in ACL reconstructed patients using 3.0 Tesla magnetic resonance imaging

INTRODUCTION

Injury to the anterior cruciate ligament (ACL) is common. While prior studies have shown that surgical reconstruction of the ACL can restore anterior-posterior kinematics, ACL-injured and reconstructed knees have been shown to have significant differences in tibial rotation when compared to uninjured knees. Our laboratory has developed an MR compatible rotational loading device to objectively quantify rotational stability of the knee following ACL injuries and reconstructions. Previous work from our group demonstrated a significant increase in total tibial rotation following ACL injuries. The current study is a prospective study on the same cohort of patients who have now undergone ACL reconstruction. We hypothesize that ACL reconstructed knees will have less tibial rotation relative to the pre-operative ACL deficient condition. We also hypothesize that ACL reconstructed knees will have greater rotational laxity when compared to healthy contralateral knees.

METHODS

Patients. Six of the ACL injured patients from our initial study who had subsequently undergone ACL reconstruction were evaluated 8.1 ± 2.9 months after surgery. All patients underwent single-bundle ACL reconstruction using anteromedial portal drilling of the femoral tunnel with identical post-operative regimens. Magnetic Resonance (MR) Imaging. Patients were placed in a supine position in the MR scanner on a custom-built loading device. Once secured in the scanner bore, an internal/external torque was applied to the foot. The tibiae were semi-automatically segmented with in-house software. Tibial rotation comparisons were made within subjects (i.e. side-to-side comparison between reconstructed and contralateral knees) and differences were explored using paired sample t-tests with significance set at p=0.05.

RESULTS

Regarding tibial rotation, in the ACL deficient state, these patients experienced an average of 5.9 ± 4.1° difference in tibial rotation between their ACL deficient and contralateral knees. However, there was a -0.2 ± 6.1° difference in tibial rotation of the ACL reconstructed knee when compared to the contralateral uninjured knee. Regarding tibial translation, ACL deficient patients showed a difference of 0.75 ± 1.4mm of anterior tibial translation between injured and healthy knees. After ACL reconstruction, there was a 0.2 ± 1.1mm difference in coupled anterior tibial translation of the ACL reconstructed knee compared to the contralateral knee. No significant differences in contact area between the two time points could be discerned.

DISCUSSION

The objective of our study was to assess the rotational laxity present in ACL reconstructed knees using a previously validated MRI-compatible rotational loading device. Our study demonstrated that ACL reconstruction can restore rotational laxity under load. This may speak to the benefit of an anteromedial drilling technique, which allows for a more horizontal and anatomically appropriate graft position.

Highly sensitive micro-plate enzyme immunoassay screening and NCI-GC-MS confirmation of flunitrazepam and its major metabolite 7-aminoflunitrazepam in hair

Flunitrazepam (Rohypnol) is a benzodiazepine used in the treatment of insomnia as a sedative hypnotic and as preanesthetic medication in European countries and Mexico. Although it has no medicinal purpose in the United States, the occurrence of its abuse is increasing. Sexual abuse of both men and women while under the influence of so-called "date-rape" drugs has been the focus of many investigations. Reported date-rape drugs include flunitrazepam (FN), clonazepam, diazepam, oxazepam, gamma-hydroxybutyrate, and many others. FN has been banned in the United States because of its alleged use in such situations. Unfortunately, the detection of FN or its metabolites 7-aminoflunitrazepam (7-AFN) and desmethylflunitrazepam in a single specimen such as urine or blood is difficult in criminal situations because of the likelihood of single-dose ingestion and the length of time since the alleged incident. Hair provides a solution to the second of these problems in that drugs tend to incorporate into hair and remain there for longer periods of time than either urine or blood. There are various techniques for the detection of FN in plasma, blood, and urine, but little work has been done with hair. Hair collection is a virtually noninvasive procedure that can supply information on drug use for several months preceding collection. The objective of this paper was to determine if a commercially available micro-plate enzyme immunoassay system was sufficiently sensitive for the routine screening of 7-AFN in hair by the development of extraction procedures and optimization of the immunoassay kit. Further, this study used the same solid-phase extraction to isolate FN and its major metabolite, 7-AFN, and gas chromatography-mass spectrometry with negative ion chemical ionization for confirmation. Two seven-point standard curves were established ranging from 0.5 pg/mg to 100 pg/mg for 7-AFN and 2.5 pg/mg to 200 pg/mg for FN with respective deuterated internal standards. A replicate analysis of controls was performed to establish inter- and intraday variabilities. Two suicide cases along with one alleged date-rape case and one case of an emergency room patient whose blood screened positive for benzodiazepines were analyzed. All the hair specimens screened positive for benzodiazepines using micro-plate enzyme immunoassay. Two cases, including the date-rape case, were negative for FN and 7-AFN, and two postmortem hair samples were confirmed positive for FN and its metabolite.

The detection of cotinine in hydrolyzed meconium samples

To date, the screening of meconium for the determination of tobacco exposure in newborns has proven difficult. It was hypothesized that cotinine forms reversible Schiff base bonds with free amino functions on proteins, therefore, hydrolysis of meconium would be necessary for the detection of 'free' cotinine. One-hundred-and-two (102) meconium samples received into our laboratory were extracted using a routine non-hydrolysis screening procedure for drugs of abuse. Separate aliquots of the specimens were hydrolyzed and re-extracted according to the same procedure. The results of the two methods were compared using a highly specific cotinine micro-plate enzyme immunoassay procedure (EIA). Of the non-hydrolyzed samples, 33% were positive for cotinine, while 79% of the hydrolyzed samples were cotinine-positive. Common drugs of abuse did not interfere with the analysis. Micro-plate EIA provides a rapid, simple and reliable screening method for the determination of cotinine in meconium following hydrolysis and extraction. In general, the meconium specimens received into our laboratory are from newborns considered to be at risk for post-natal problems due to suspected drug and/or alcohol abuse during pregnancy.

The detection of cocaine in hair specimens using micro-plate enzyme immunoassay

The analysis of hair for drugs of abuse is becoming increasingly popular and is under consideration by the Division of Health and Human Services as a possible alternative or adjunct to urinalysis in workplace programs. The detection of cocaine in human hair using a commercially available micro-plate enzyme immunoassay is described for the first time. Sample size and incubation time were the major variables in the optimization of the method. In order to validate the procedure, the method was applied to 105 consecutive hair samples routinely received into our laboratory. The samples were simultaneously analyzed by the Micro-Plate immunoassay (EIA), as well as our current fluorescence polarization immunoassay (FPIA) procedure and gas chromatography-mass spectrometry (GC/MS). The sensitivity of the EIA and FPIA assays were 75% and 67.8% respectively; specificity 97.4% and 80.5% respectively; and efficiency 91.4 and 77.1% respectively. The Micro-Plate EIA was shown to be a valid alternative to other immunoassay screening methods for the detection of cocaine in hair by demonstrating increased sensitivity, specificity and efficiency over our current technique.

Identification of the major positive regulators of c-myb expression in hematopoietic cells of different lineages

The c-myb gene is primarily expressed in hematopoietic cells, and it is overexpressed in many leukemias. The regulation of its expression is of critical importance in hematopoietic cells. We identified the major positive regulatory sites in the 5'-flanking sequence of the human c-myb gene, and we found that the positive regulators differed in cells of different lineages. In the Molt-4 T-cell line, two Ets-like binding sites were required for the expression of c-myb. The 5' site played a minor role in the regulation of c-myb expression, and we demonstrated that a protein of 67 kDa bound to this site. Antibodies against Ets proteins showed no cross-reactivity with this protein. We showed that Ets-1 bound to the 3'-regulatory site in the c-myb promoter by electrophoretic mobility shift assay and antibody studies. Both of these Ets-like binding sites were nonfunctional in the DHL-9 B-cell line and the K562 myeloid cell line. We identified a novel transcription factor of 50.5 kDa that was required for expression of c-myb in these cell lines.

Identification of an inducible regulator of c-myb expression during T-cell activation

Resting T cells express very low levels of c-Myb protein. During T-cell activation, c-myb expression is induced and much of the increase in expression occurs at the transcriptional level. We identified a region of the c-myb 5' flanking sequence that increased c-myb expression during T-cell activation. In vivo footprinting by ligation-mediated PCR was performed to correlate in vivo protein binding with functional activity. A protein footprint was visible over this region of the c-myb 5' flanking sequence in activated T cells but not in unactivated T cells. An electrophoretic mobility shift assay (EMSA) with nuclear extract from activated T cells and an oligonucleotide of this binding site demonstrated a new protein-DNA complex, referred to as CMAT for c-myb in activated T cells; this complex was not present in unactivated T cells. Because the binding site showed some sequence similarity with the nuclear factor of activated T cells (NFAT) binding site, we compared the kinetics of induction of the two binding complexes and the molecular masses of the two proteins. Studies of the kinetics of induction showed that the NFAT EMSA binding complex appeared earlier than the CMAT complex. The NFAT protein migrated more slowly in a sodium dodecyl sulfate-polyacrylamide gel than the CMAT protein did. In addition, an antibody against NFAT did not cross-react with the CMAT protein. The appearance of the CMAT binding complex was inhibited by both cyclosporin A and rapamycin. The CMAT protein appears to be a novel inducible protein involved in the regulation of c-myb expression during T-cell activation.