Superior Capsular Reconstruction Combined With Lower Trapezius Tendon Transfer Improves the Biomechanics in Posterosuperior Massive Rotator Cuff Tears

BACKGROUND

Surgical treatments for chronic posterosuperior massive rotator cuff tear (MRCT) are still controversial. Superior capsular reconstruction (SCR), which provides a static stabilizer to decrease superior humeral head translation, and lower trapezius tendon transfer (LTTT) with centralization of the humeral head, which prevents superior humeral head migration, are potential surgical options. To date, SCR combined with LTTT has not been fully investigated.

HYPOTHESIS

Restoration of static stabilizer and dynamic stabilizer together would effectively improve shoulder kinematics in posterosuperior MRCT.

STUDY DESIGN

Controlled laboratory study.

METHODS

A custom-made shoulder mechanics testing system was used to test 8 fresh-frozen cadaveric shoulders. The testing conditions were as follows: (1) intact; (2) posterosuperior MRCT (supraspinatus and infraspinatus removed); (3) SCR using the fascia lata; (4) LTTT; and (5) SCR combined with LTTT. The total rotational range of motion (ROM), superior translation, anteroposterior translation, and peak subacromial contact pressure were evaluated at 0°, 30°, and 60° of shoulder abduction. Repeated-measures analysis of variance and Tukey post hoc tests were performed.

RESULTS

The total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure increased in posterosuperior MRCTs (all, P < .05). The rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0° and 30° of shoulder abduction decreased in SCR (all, P < .05). However, there was no significant improvement in rotational ROM, superior translation, and peak subacromial contact pressure at 60° of shoulder abduction (P > .05). LTTT resulted in a significant decrease in the superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (P < .05). SCR combined with LTTT restored the total rotational ROM, superior translation, anteroposterior translation, and peak subacromial contact pressure at 0°, 30°, and 60° of shoulder abduction (all, P < .05).

CONCLUSION

In the cadaveric model, SCR combined with LTTT showed improved shoulder kinematics and contact pressures in the posterosuperior MRCT model compared with SCR or LTTT alone.

CLINICAL RELEVANCE

SCR combined with LTTT may be regarded as an alternative surgical procedure for posterosuperior MRCTs.

Prevalence, Timing, Locational Distribution, and Risk Factors for Heterotopic Ossification After Elbow Arthroscopy

BACKGROUND

Arthroscopic techniques aim to reduce complications and accelerate recovery of the elbow after treatments for posttraumatic stiffness, arthritis diseases, lateral epicondylitis, ligament reconstruction, and elbow trauma. However, data on the true prevalence and characteristics of heterotopic ossification (HO) formation after elbow arthroscopy are limited.

PURPOSE

To investigate the prevalence, timing, locational distribution, and risk factors of HO after elbow arthroscopy.

STUDY DESIGN

Cohort study; Level of evidence, 4.

METHODS

Data on 205 patients undergoing elbow arthroscopy by a single senior elbow surgeon at a single institution between May 2011 and January 2022 were retrospectively reviewed. The patients were evaluated at 2 weeks, 8 weeks, 6 months, and then annually after surgery or more frequently if HO developed, with a minimum of 1 year of postoperative follow-up. Postoperative anteroposterior and lateral elbow radiographs were taken at 2 weeks to rule out fracture and at 8 weeks to identify HO. The clinical outcomes were evaluated based on the pain visual analog scale; the shortened version of the Disabilities of the Arm, Shoulder and Hand score; Mayo Elbow Performance Score; and the Single Assessment Numeric Evaluation scores before and after surgery. Bivariate logistic regression analyses were used to determine factors affecting HO prevalence.

RESULTS

Thirteen (12 male, 1 female) of 205 (6.3%) patients developed HO, with 10 (76.9%) with HO that formed on the medial compartment of the elbow. Ten (76.9%) patients were diagnosed at 8 weeks after arthroscopic surgery, 1 (7.7%) at 6 months after surgery, and 2 (15.4%) at 12 months after surgery. HO was not found at 2 weeks after surgery in any patient. The mean follow-up time was 3.5 years (range, 1.0-11.8 years). Eleven asymptomatic patients were treated nonoperatively, and 2 symptomatic patients underwent HO excision arthroscopically or had a combination of open surgery and arthroscopy. Age was a protective factor for HO formation (odds ratio [OR], 0.953; 95% CI, 0.910-0.999; P = .047). The risk factors for HO formation were tourniquet time (OR, 1.042; 95% CI, 1.019-1.065; P < .001) and surgical time (OR, 1.026; 95% CI, 1.011-1.041; P < .001).

CONCLUSION

Among 205 patients who underwent elbow arthroscopy, HO was a minor complication of elbow arthroscopy, with a prevalence rate of 6.3%, and was usually located on the medial compartment of the elbow. Although the presence of HO may not affect the clinical outcomes in most patients, it should be carefully monitored for a minimum of 8 weeks postoperatively. Younger age, longer tourniquet time, and longer surgical time contributed to HO formation after elbow arthroscopy.

Radiologically severe osteoarthritis is related to worse clinical outcomes after arthroscopic osteocapsular arthroplasty in primary elbow osteoarthritis at medium-term follow-up: a retrospective cohort study

HYPOTHESIS

This study aimed to compare the clinical outcomes after arthroscopic osteocapsular arthroplasty (OCA) at medium-term follow-up according to the radiologic severity of primary elbow osteoarthritis (OA) and assess serial changes in clinical outcomes in each group.

METHODS

Patients treated from January 2010 to April 2019 with arthroscopic OCA for primary elbow OA with a minimum of 3 years' follow-up were retrospectively assessed regarding range of motion (ROM), visual analog scale (VAS) pain score, and Mayo Elbow Performance Score (MEPS) preoperatively, at short-term follow-up (3-12 months postoperatively), and at medium-term follow-up (≥3 years after surgery). Preoperative computed tomography was performed to evaluate the radiologic severity of OA using the Kwak classification. Clinical outcomes were compared according to the radiologic severity of OA by their absolute values and the number of patients achieving the patient acceptable symptomatic state (PASS). Serial changes in the clinical outcomes in each subgroup were also assessed.

RESULTS

Of the 43 patients, 14, 18, and 11 were classified as the stage I, II, and III groups, respectively; the mean follow-up duration was 71.3 ± 28.9 months, and the mean age was 56.5 ± 7.2 years. At medium-term follow-up, the stage I group had a better ROM arc (stage I, 114° ± 14°; stage II, 100° ± 23°; and stage III, 97° ± 20°; P = .067) and VAS pain score (stage I, 0.9 ± 1.3; stage II, 1.8 ± 2.1; and stage III, 2.4 ± 2.1; P = .168) than the stage II and III groups without reaching statistical significance, whereas the stage I group had a significantly better MEPS (stage I, 93.2 ± 7.5; stage II, 84.7 ± 11.9; and stage III, 78.6 ± 15.2; P = .017) than the stage III group. The percentages of patients achieving the PASS for the ROM arc (P = .684) and VAS pain score (P = .398) were comparable between the 3 groups; however, the percentage achieving the PASS for the MEPS was significantly higher in the stage I group than in the stage III group (100.0% vs. 54.5%, P = .016). During serial assessment, all clinical outcomes tended to improve at the short-term follow-up. Compared with the short-term period, the ROM arc tended to decrease at the medium-term follow-up whereas the VAS pain score and MEPS overall did not show significant changes.

CONCLUSION

After arthroscopic OCA, the stage I group showed an overall better ROM arc and pain score than the stage II and III groups at medium-term follow-up, whereas the stage I group showed a significantly better MEPS and higher percentage of patients achieving the PASS for the MEPS than the stage III group.

Evaluation of a New MRI-Based Classification of Graft Status After Superior Capsule Reconstruction

Background

A classification system for the graft state after superior capsule reconstruction (SCR) using magnetic resonance imaging (MRI) has not been described previously.

Purpose

To introduce a new, MRI-based classification system for graft integrity after SCR and to evaluate the system according to postoperative outcomes.

Study Design

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

Method

Included were 62 consecutive patients who underwent SCR using autologous fascia lata graft between January 2013 and April 2021. Postoperative outcomes were assessed (American Shoulder and Elbow Surgeons [ASES] score, Constant score, pain visual analog scale [pVAS], range of motion [ROM], acromiohumeral distance [AHD], Hamada grade). Graft status was classified by 2 orthopaedic surgeons on postoperative MRI in accordance with the signal intensity and the presence or extent of the tear, as follows: type 1 (hypointense signal without tear), type 2 (hyperintense signal without tear), type 3 (partial-thickness tear), type 4 (full-thickness tear with partial continuity), and type 5 (full-thickness tear with complete discontinuity). Intra- and interobserver agreement were assessed using Cohen kappa. The correlation between postoperative outcomes (ASES score, Constant score, pVAS, ROM, AHD, and Hamada grade) and the SCR graft classification system was assessed with the Pearson correlation coefficient, and the outcomes were compared according to classification type.

Results

Patients were classified according to the new system as follows: type 1 (n = 15), type 2 (n = 20), type 3 (n = 7), type 4 (n = 8), and type 5 (n = 12). There was excellent interobserver agreement (κ = 0.819) and intraobserver agreement (κ = 0.937 and 0.919). The classification system showed a moderate to high correlation with the ASES score (r = -0.451; P = .001), pVAS (r = 0.359; P = .005), AHD (r = -0.642; P < .001), and Hamada grade (r = 0.414; P < .001). Patients classified as having types 1 and 2 showed better outcomes in terms of ASES score, pVAS, ROM, and AHD compared with type 5 patients (P ≤ .021 for all).

Conclusion

The new classification system was highly reproducible and showed clinical utility for both radiological and clinical evaluation after SCR.

Clinical and Radiological Outcomes of Arthroscopic Superior Capsular Reconstruction Versus Primary Rotator Cuff Repair in Massive Rotator Cuff Tears: A Propensity Score-Matched Study

BACKGROUND

Arthroscopic superior capsular reconstruction (aSCR) has emerged as a treatment option for managing massive rotator cuff tears (MRCTs) given the unpredictable results after an arthroscopic rotator cuff repair (aRCR). Yet, few comparative studies of aSCR and aRCR have been conducted.

PURPOSE

To compare the clinical and radiological outcomes between aRCR and aSCR in patients with MRCT.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 163 cases of MRCT from 2010 to 2020 with follow-up ≥2 years were retrospectively reviewed. Among them, 102 had aRCR and 61 had aSCR using fascia lata autograft. Propensity score matching was used to select controls matched for age, sex, diabetes mellitus, osteoporosis, preoperative American Shoulder and Elbow Surgeons score, Single Assessment Numeric Evaluation score, Constant score, pain visual analog scale (pVAS) score, range of motion (ROM), tear size, global fatty degeneration index, and acromiohumeral distance (AHD). Last, 33 cases in each group were selected after propensity score matching. Radiological assessment was conducted using serial postoperative magnetic resonance imaging. Pre- and postoperative findings-including American Shoulder and Elbow Surgeons, pVAS, Single Assessment Numeric Evaluation, and Constant scores and ROM-were assessed to compare clinical outcomes. For radiological outcomes, global fatty degeneration index, AHD, and healing rate were evaluated. Healing failure was defined as Sugaya classification IV or V in the aRCR group, as compared with a full-thickness tear of the graft in the aSCR group, which corresponded to Sugaya classification IV or V.

RESULTS

Postoperative clinical outcomes were significantly improved at the final follow-up in both groups. In the aSCR group, postoperative forward flexion, pVAS, and AHD were significantly improved as compared with the aRCR group (mean, 161° vs 148° [P = .02]; 1.03 vs 1.64 [P = .047]; 7.00 vs 5.23 mm [P < .001], respectively). The healing rate was 20 of 33 (60.6%) for aRCR and 29 of 33 (87.9%) for aSCR (P = .022).

CONCLUSION

aSCR and aRCR are effective and reliable treatment options for MRCT. However, when compared with aRCR, aSCR showed improved clinical outcomes, including pVAS score, postoperative ROM, and favorable radiological findings, including AHD and a higher healing rate.

Clinical Outcomes of Revision Arthroscopic Osteocapsular Arthroplasty in Primary Elbow Osteoarthritis: A Retrospective Cohort Study

BACKGROUND

Arthroscopic osteocapsular arthroplasty (OCA) achieves significant medium-term outcomes in patients with primary elbow osteoarthritis (OA); however, outcomes after revision arthroscopic OCA are not well known.

PURPOSE

To assess clinical outcomes after revision arthroscopic OCA as compared with those after primary surgery in patients with OA.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent arthroscopic OCA attributed to primary elbow OA between January 2010 and July 2020 were enrolled. Range of motion (ROM), visual analog scale (VAS) pain score, and Mayo Elbow Performance Score (MEPS) were assessed. Operation time and complications were assessed by chart review. Clinical outcomes between the primary and revision surgery groups were compared, and subgroup analysis for radiologically severe OA was performed.

RESULTS

Data from 61 patients were analyzed (primary, n = 53; revision, n = 8). The mean ± SD age was 56.3 ± 8.5 and 54.3 ± 8.9 years in the primary and revision groups, respectively. The primary group had significantly better ROM arcs preoperatively (89.9°± 20.3° vs 71.3°± 22.3°; P = .021) and postoperatively (112.4°± 17.1° vs 96.9°± 16.5°; P = .019) than the revision group; however, the degree of improvement was comparable (P = .445). Postoperative VAS pain score (P = .164) and MEPS (P = .581) were comparable between the groups, as were the degrees of improvement in VAS pain score (P = .691) and MEPS (P = .604). The revision group required a significantly longer operative time than the primary group (P = .004) and had a nonsignificant higher complication rate (P = .065). Subgroup analysis showed that radiologically severe cases in the primary group had significantly better preoperative (P = .010) and postoperative (P = .030) ROM arcs than the revision group and a comparable postoperative VAS pain score (P = .155) and MEPS (P = .658).

CONCLUSION

Revision arthroscopic OCA is a favorable treatment option for primary elbow OA with recurrent symptoms. Postoperative ROM arc was worse after revision surgery as compared with primary surgery; however, the degree of improvement was comparable. Postoperative VAS pain score and MEPS were comparable with primary surgery.

Serial Changes in Clinical Outcomes After Arthroscopic Osteocapsular Arthroplasty for Primary Elbow Osteoarthritis: A Medium-term Follow-up Study

Background

Arthroscopic osteocapsular arthroplasty (OCA) shows promising short-term outcomes for primary elbow osteoarthritis (OA). However, serial changes in clinical outcomes for medium-term follow-up are not well known.

Purpose

To evaluate clinical outcomes after arthroscopic OCA in primary elbow OA from preoperative to short- and medium-term follow-up and to analyze the correlation between the time from short- to medium-term follow-up and the changes in clinical outcomes between the periods.

Study Design

Case series; Level of evidence, 4.

Methods

Patients with primary elbow OA who were treated with arthroscopic OCA between January 2010 and April 2020 were evaluated. Elbow range of motion (ROM), visual analog scale (VAS) for pain, and Mayo Elbow Performance Score (MEPS) were assessed preoperatively and at short-term (3-12 months) and medium-term (≥2 years) follow-up. The correlation between the time from short- to medium-term follow-up and the changes in clinical outcomes was analyzed using the Pearson correlation coefficient.

Results

Included were 56 patients who underwent short-term follow-up (mean [range], 5.9 [3-12] months) and medium-term follow-up (62.2 [24-129] months) after arthroscopic OCA. When compared with preoperative values, significant improvements were seen at short-term follow-up: ROM (from 89.4° to 111.7°; P < .001), VAS for pain (from 4.9 to 2.0; P < .001), and MEPS (from 62.3 to 83.7; P < .001). From short- to medium-term follow-up, ROM decreased (from 111.7° to 105.4°; P = .001) while VAS for pain (from 2.0 to 1.4; P = .031) and MEPS (from 83.7 to 87.8; P = .016) improved. All outcomes improved significantly at medium-term follow-up as compared with preoperative values (P < .001 for all). The time between short- and medium-term follow-up had a significant positive correlation with decreased ROM (r = 0.290; P = .030) and a significant negative correlation with improvement in MEPS (r = -0.274; P = .041).

Conclusion

Serial assessment of patients with primary elbow OA who underwent arthroscopic OCA showed that the clinical outcomes improved from preoperative assessment to short- and medium-term follow-up, although ROM decreased between short- and medium-term follow-up. VAS for pain and MEPS showed continued improvement until medium-term follow-up.

Early Postoperative MRI Evaluation of a Fascia Lata Autograft With and Without Polypropylene Mesh Augmentation After Superior Capsular Reconstruction

BACKGROUND

Recently, a polypropylene mesh has been introduced and reported to improve clinical outcomes after superior capsular reconstruction (SCR) using a fascia lata autograft (FLA). However, mesh-related events such as a foreign body response may trigger inflammation, which might affect graft healing and remodeling.

PURPOSE/HYPOTHESIS

The aim was to investigate whether the healing and remodeling of an FLA were affected by the use of a mesh by comparing the signal intensity of an FLA-alone group vs an FLA + Mesh group on postoperative magnetic resonance imaging (MRI). The hypothesis was that the use of a mesh would decrease the MRI signal intensity of FLA during the early postoperative phase.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who had undergone SCR using an FLA with or without a mesh between March 2013 and August 2021 were retrospectively analyzed. Follow-up MRI was performed at 3 months. A total of 78 patients (24 in the FLA group and 54 in the FLA + Mesh group) with intact grafts were included. Graft remodeling was evaluated by analyzing the signal-to-noise quotient (SNQ) at the humeral, mid-substance, and glenoid sites. Theoretically, lower SNQ ratios indicate higher strength and better healing of the graft.

RESULTS

The mean SNQ was 30.603 (range, 11.790-72.710) in the FLA group and 18.367 (range, 4.464-69.500) in the FLA + Mesh group (P < .001). Furthermore, significant differences were found between the 2 groups at the humeral and mid-substance sites (37.863 [range, 5.092-81.187] vs 15.512 [range, 1.814-80.869], P < .001; and 29.168 [range, 6.103-73.900] vs 16.878 [range, 2.454-92.416], P = .003; respectively). However, there was no difference between the 2 groups at the glenoid site (25.346 [range, 7.565-86.353] vs 20.354 [range, 3.732-88.468], P = .057).

CONCLUSION

At the 3-month follow-up, the FLA + Mesh group showed a lower MRI signal intensity than the FLA group. The healing and remodeling of an FLA may be enhanced when a mesh is used.

Postoperative MRI signal intensity correlates functional outcomes after superior capsular reconstruction

PURPOSE

Superior capsular reconstruction (SCR) using fascia lata autograft has been performed for irreparable rotator cuff tear recently. The signal-to-noise quotient (SNQ) of the graft on magnetic resonance imaging (MRI) may reflect the degree of graft maturity and healing. However, how SNQ changes with graft remodelling and time and whether this change correlates with postoperative clinical outcomes after SCR remain unknown. This study aimed to explore the correlation between SNQ of the fascia lata autograft and clinical functional outcomes after SCR.

METHODS

Patients with irreparable posterosuperior rotator cuff tear undergoing SCR using fascia lata autograft between 2013 and 2017 were retrospectively analysed. For clinical outcomes, the American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score, Single Assessment Numeric Evaluation (SANE), and Visual Analogue Scale (VAS) for pain and range of motion (ROM; forward flexion and external rotation) were evaluated at postoperative 6 and 12 months. Signal intensity of the humeral, mid-substance, and glenoid sites and background were measured to calculate the SNQ values on follow-up MRI at 3 and 12 months. The correlations between clinical outcomes and SNQ at different time points were then analysed.

RESULTS

A total of 15 patients were enrolled in the study. The mean postoperative VAS score significantly increased at postoperative 6 months and significantly decreased at postoperative 12 months. Except for forward flexion, all other functional outcomes were improved at postoperative 6 months. Analysis of MRI showed SNQ at the humeral (SNQh), mid-substance, and glenoid sites decreased from postoperative 3 to 12 months with a statistical significance detected in SNQh (P < 0.01). Correlation analyses showed that the SNQh values negatively correlated with VAS, ASES, Constant-Murley score, SANE, ROM (forward flexion), and ROM (external rotation) (all P < 0.05).

CONCLUSION

SNQ of the fascia lata autograft decreased with time in patients receiving SCR. SNQ at the humeral site was negatively correlated with clinical outcomes.

LEVEL OF EVIDENCE

III.

Staged revision still works for chronic and deep infection of total elbow arthroplasty?

Purpose: Infected total elbow arthroplasty (TEA) is challenging. We evaluate the clinical and radiologic outcomes for chronic and deep infection of TEA with two-stage revision surgery. Methods: A total of 10 elbows were included in the study. The mean age was 69.1 ± 15 years (range, 34–83 years). The mean follow-up was 62 (range, 24–108) months. The clinical outcomes were assessed using a visual analog scale (VAS), range of motion (ROM) arc, and Mayo elbow performance score (MEPS). Moreover, radiographic outcomes, time to revision, pathogenic bacteria, preoperative complications, and disease period were evaluated. Results: Mean preoperative VAS score of 6.1 had improved to 3.3. Mean preoperative ROM was 68° (flexion-extension), which improved to 86.7°. Mean preoperative MEPS was 46 (range, 0–70), which improved to 75.5 (range, 35–85). The mean disease duration was 8.4 months (range, 5–20 months). The most common causative organism was methicillin-resistant Staphylococcus aureus. The second revision rate was 80% at the final follow-up. Radiographic outcome at final follow-up showed that 3 (30%) of 10 patients exhibited radiolucency evidence around the components. Three patients showed nonprogressive radiolucency around the implant interfaces without other indications of infection at the most recent follow-up. Conclusion: In patients with chronic and deep infection of TEA, two-stage revision can be an affordable option for eradication of the infection, relieving pain, and restoring joint function. However, the high second revision rate owing to bone and soft-tissue deficits remains a critical issue.

Level of evidence: Level IV, Case series, Treatment study

Psoas Muscle Volume as an Opportunistic Diagnostic Tool to Assess Sarcopenia in Patients with Hip Fractures: A Retrospective Cohort Study

PURPOSE

This study aims to determine whether the psoas volume measured from a pelvic computed tomography (CT) could be a potential opportunistic diagnostic tool to measure muscle mass and sarcopenia in patients with hip fractures.

METHODS

This was a retrospective cohort study. In total; 57 consecutive patients diagnosed with hip fractures who underwent surgery were enrolled. A cross-sectional area of the psoas muscle was measured at the lumbar (L) 3 and L4 vertebrae from a pelvic CT for the diagnosis of hip fractures. The psoas muscle volume was calculated with a three-dimensional modeling software program. The appendicular skeletal muscle mass (ASM) and preoperative handgrip strength (HS) were measured. The correlations between the psoas muscle volume/area and ASM/HS were assessed. Data on patient demographics; postoperative complication; length of hospital stay; and Koval scores were also recorded and analyzed with respect to the psoas muscle area/volume.

RESULTS

The psoas muscle volume and adjusted values were significantly correlated with ASM; which showed a stronger correlation than the psoas muscle area did at the L3 or L4 level. HS was correlated with the psoas volume or adjusted values; but not with the cross-sectional area of the psoas muscle. Among the adjusted values; the psoas muscle volume adjusted for the patient's height (m²) showed a strongest correlation with ASM and HS. The psoas muscle volume was not significantly correlated with postoperative complications or short-term functional outcomes.

CONCLUSIONS

The psoas muscle volume measured from a pelvic CT for the diagnosis of hip fractures showed a stronger correlation with ASM and HS than the cross-sectional area did. Therefore; the psoas muscle volume could be a potential diagnostic tool to assess the quantity of the skeletal muscle in patients with hip fractures without an additional examination.

c-Jun N-terminal Kinase (JNK) induces phosphorylation of amyloid precursor protein (APP) at Thr668, in okadaic acid-induced neurodegeneration

Several lines of evidence have revealed that phosphorylation of amyloid precursor protein (APP) at Thr668 is involved in the pathogenesis of Alzheimer's disease (AD). Okadaic acid (OA), a protein phosphatase-2A inhibitor, has been used in AD research models to increase tau phosphorylation and induce neuronal death. We previously showed that OA increased levels of APP and induced accumulation of APP in axonal swellings. In this study, we found that in OA-treated neurons, phosphorylation of APP at Thr668 increased and accumulated in axonal swellings by c-jun N-terminal kinase (JNK), and not by Cdk5 or ERK/MAPK. These results suggest that JNK may be one of therapeutic targets for the treatment of AD. [BMB Reports 2016; 49(7): 376-381].

Efficacy of multidisciplinary approach in treatment of constipation: a pilot study

OBJECTIVE

To evaluate a multidisciplinary Hong Kong treatment programme for patients with constipation.

DESIGN

Pilot study.

SETTING

A joint collaboration among the departments of surgery, physiotherapy, and dietetics in a regional hospital in Hong Kong.

PATIENTS

Thirty-one constipated patients with normal colonic transit and pelvic floor dyssynergia.

INTERVENTION

Multidisciplinary treatment including dietary modification, bowel habit adjustment, and physiotherapy.

MAIN OUTCOME MEASURES

Anorectal manometry, fibre intake, subjective improvement, bowel frequency, Bristol score, and straining time and effort.

RESULTS

Significant improvement was found in mean fibre intake, straining time and effort, but not in anal manometric results. A total of 78% of patients demonstrated more than 50% improvement in subjective symptoms, whereas 70% of the patients enjoyed objective improvement in pelvic floor dyssynergia documented by electromyography and anal pressure during a push effort.

CONCLUSION

The multidisciplinary rehabilitative programme for constipated patients significantly improved symptoms. Electromyography and anal pressure during a push effort are useful tools for objective assessment of the treatment effect.

Solution structure of the second extracellular loop of human thromboxane A2 receptor

Thromboxane A(2) receptor (TP receptor), a prostanoid receptor, belongs to the G protein-coupled receptor family, composed of three intracellular loops and three extracellular loops connecting seven transmembrane helices. The highly conserved extracellular domains of the prostanoid receptors were found in the second extracellular loop (eLP(2)), which was proposed to be involved in ligand recognition. The 3D structure of the eLP(2) would help to further explain the ligand binding mechanism. Analysis of the human TP receptor model generated from molecular modeling based on bacteriorhodopsin crystallographic structure indicated that about 12-14 A separates the N- and C-termini of the extra- and intracellular loops. Synthetic loop peptides whose termini are constrained to this separation are presumably more likely to mimic the native loop structure than the corresponding loop region peptide with unrestricted ends. To test this new concept, a peptide corresponding to the eLP(2) (residues 173-193) of the TP receptor has been made with the N- and C-termini connected by a homocysteine disulfide bond. Through 2D nuclear magnetic resonance (NMR) experiments, complete (1)H NMR assignments, and structural construction, the overall 3D structure of the peptide was determined. The structure shows two beta-turns at residues 180 and 185. The distance between the N- and C-termini of the peptide shown in the NMR structure is 14.2 A, which matched the distance (14.5 A) between the two transmembrane helices connecting the eLP(2) in the TP receptor model. This suggests that the approach using the constrained loop peptides greatly increases the likelihood of solving the whole 3D structures of the extra- and the intracellular domains of the TP receptor. This approach may also be useful in structural studies of the extramembrane loops of other G protein-coupled receptors.

Identification of the substrate interaction site in the N-terminal membrane anchor segment of thromboxane A2 synthase by determination of its substrate analog conformational changes using high resolution NMR technique

The present studies describe an investigation for the interaction of N-terminal membrane anchor domain of thromboxane A(2) synthase (TXAS) with its substrate analog in a membrane-bound environment using the two-dimensional NMR technique. TXAS and prostaglandin I(2) synthase (PGIS), respectively, convert the same substrate, prostaglandin H(2) (PGH(2)), to thromboxane A(2) and prostaglandin I(2), which have opposite biological functions. Our topology studies have indicated that the N-terminal region of TXAS has a longer N-terminal endoplasmic reticulum (ER) membrane anchor region compared with the same segment proposed for PGIS. The differences in their interaction with the ER membrane may have an important impact to facilitate their common substrate, PGH(2), across the membrane into their active sites from the luminal to the cytoplasmic side of the ER. To test this hypothesis, we first investigated the interaction of the TXAS N-terminal membrane anchor domain with its substrate analog. A synthetic peptide corresponding to the N-terminal membrane anchor domain (residues 1-35) of TXAS, which adopted a stable helical structure and exhibited a membrane anchor function in the membrane-bound environment, was used to interact with a stable PGH(2) analog,. High resolution two-dimensional NMR experiments, NOESY and TOCSY, were performed to solve the solution structures of in a membrane-mimicking environment using dodecylphosphocholine micelles. Different conformations were clearly observed in the presence and absence of the TXAS N-terminal membrane anchor domain. Through combination of the two-dimensional NMR experiments, completed (1)H NMR assignments of were obtained, and the data were used to construct three-dimensional structures of in H(2)O and dodecylphosphocholine micelles, showing the detailed conformation change upon the interaction with the membrane anchor domain. The observation supported the presence of a substrate interaction site in the N-terminal region. The combination of the structural information of and was able to simulate a solution structure of the unstable TXAS and PGIS substrate, PGH(2).