Rapid and Highly Stable Membrane Reconstitution by LAiR Enables the Study of Physiological Integral Membrane Protein Functions

Functional reintegration into lipid environments represents a major challenge for in vitro investigation of integral membrane proteins (IMPs). Here, we report a new approach, termed LMNG Auto-insertion Reintegration (LAiR), for reintegration of IMPs into lipid bilayers within minutes. The resulting proteoliposomes displayed an unprecedented capability to maintain proton gradients and long-term stability. LAiR allowed for monitoring catalysis of a membrane-bound, physiologically relevant polyisoprenoid quinone substrate by Escherichia coli cytochromes bo ₃ (cbo ₃) and bd (cbd) under control of the proton motive force. LAiR also facilitated bulk-phase detection and physiological assessment of the "proton leak" in cbo ₃, a controversial catalytic state that previously was only approachable at the single-molecule level. LAiR maintained the multisubunit integrity and higher-order oligomeric states of the delicate mammalian F-ATP synthase. Given that LAiR can be applied to both liposomes and planar membrane bilayers and is compatible with IMPs and lipids from prokaryotic and eukaryotic sources, we anticipate LAiR to be applied broadly across basic research, pharmaceutical applications, and biotechnology.

Cytochrome bd-I from Escherichia coli is catalytically active in the absence of the CydH subunit

Cytochrome bd-I from Escherichia coli is a terminal oxidase in the respiratory chain that plays an important role under stress conditions. Cytochrome bd-I was thought to consist of the major subunits CydA and CydB plus the small CydX subunit. Recent high-resolution structures of cytochrome bd-I demonstrated the presence of an additional subunit, CydH/CydY (called CydH here), the function of which is unclear. In this report, we show that in the absence of CydH, cytochrome bd-I is catalytically active, can sustain bacterial growth and displays haem spectra and susceptibility for haem-binding inhibitors comparable to the wild-type enzyme. Removal of CydH did not elicit catalase activity of cytochrome bd-I in our experimental system. Taken together, in the absence of the CydH subunit cytochrome bd-I retained key enzymatic properties.

[Current trends in reverse fracture arthroplasty]

The reliable results of reverse arthroplasty have made this the preferred treatment method for non-reconstructable proximal humeral fractures. The individual consideration of the patient and the morphological features of the fractures are essential. Computed tomography (CT) images provide crucial information on the perfusion of the humeral head relevant for the prognosis and treatment. In this context a differentiation must be made between hard and soft criteria against a reconstruction. Tuberosities should be reduced whenever possible, because reverse arthroplasty with healed tuberosities provides a better range of motion and more strength for external rotation and anteversion, less complications and longer survival rates. In recent years the trend has been towards anatomical designs of prostheses with a humeral inclination of 135°. Revision rates for primary fracture prostheses are overall low with instability as the main reason for revision surgery, followed by periprosthetic fractures and infections. Reverse fracture arthroplasty has comparable or better clinical results compared to conservative treatment, osteosynthesis for geriatric patients, hemiarthroplasty and prosthesis implantation by elective surgery. Reverse arthroplasties, which were implanted in conditions of fracture sequelae, did not achieve significantly poorer clinical outcome at mid-term follow-up and can significantly improve shoulder function.

The carboxy-terminal insert in the Q-loop is needed for functionality of Escherichia coli cytochrome bd-I

Cytochrome bd, a component of the prokaryotic respiratory chain, is important under physiological stress and during pathogenicity. Electrons from quinol substrates are passed on via heme groups in the CydA subunit and used to reduce molecular oxygen. Close to the quinol binding site, CydA displays a periplasmic hydrophilic loop called Q-loop that is essential for quinol oxidation. In the carboxy-terminal part of this loop, CydA from Escherichia coli and other proteobacteria harbors an insert of ~60 residues with unknown function. In the current work, we demonstrate that growth of the multiple-deletion strain E. coli MB43∆cydA (∆cydA∆cydB∆appB∆cyoB∆nuoB) can be enhanced by transformation with E. coli cytochrome bd-I and we utilize this system for assessment of Q-loop mutants. Deletion of the cytochrome bd-I Q-loop insert abolished MB43∆cydA growth recovery. Swapping the cytochrome bd-I Q-loop for the Q-loop from Geobacillus thermodenitrificans or Mycobacterium tuberculosis CydA, which lack the insert, did not enhance the growth of MB43∆cydA, whereas swapping for the Q-loop from E. coli cytochrome bd-II recovered growth. Alanine scanning experiments identified the cytochrome bd-I Q-loop insert regions Ile³¹⁸-Met³²², Gln³³⁸-Asp³⁴², Tyr³⁵³-Leu³⁵⁷, and Thr³⁶⁸-Ile³⁷² as important for enzyme functionality. Those mutants that completely failed to recover growth of MB43∆cydA also lacked oxygen consumption activity and heme absorption peaks. Moreover, we were not able to isolate cytochrome bd-I from these inactive mutants. The results indicate that the cytochrome bd Q-loop exhibits low plasticity and that the Q-loop insert in E. coli is needed for complete, stable, assembly of cytochrome bd-I.

[Plate osteosynthesis after patellar fracture - the technique and initial results of a prospective study]

BACKGROUND

Tension band wiring after patellar fractures is related to a high number of implant-related complications (22-53 %). Revision surgery is necessary in 10-55 % of patients mostly with unsatisfactory results. The patella plate is an alternative treatment with the advantages of locked plating. The purpose of this study was to evaluate the first clinical prospective results and complications of this new implant.

MATERIALS AND METHODS

Between April 2013 and May 2015 all patients that were treated with locked plating for patella fractures were included in this prospective study. Patients were followed-up clinically after six weeks and six months.

RESULTS

Included in this study were 17 patients, 6 women and 11 men, with a mean age of 58 years (19-87). The knee range of motion was 120° after 6 weeks and improved to 138° after 6 months, corresponding to 84 % and 97 % of the range of motion of the healthy opposite knee. The Tegner activity scale increased from 2,5 to 3,5 (initial value: 4), the Lysholm score increased from 78 to 92 points (initial value: 97) and the Kujala score increased from 72 to 88 points (initial value: 96). Two complications occurred: one patient had a reactive bursitis prepatellaris and one patient sustained a loss of reduction.

CONCLUSION

Locked plating of patella fractures is a reliable alternative treatment with good functional outcomes and low complication rates.

The anti-mycobacterial activity of the cytochrome bcc inhibitor Q203 can be enhanced by small-molecule inhibition of cytochrome bd

Mycobacterial energy metabolism currently attracts strong attention as new target space for development of anti-tuberculosis drugs. The imidazopyridine Q203 targets the cytochrome bcc complex of the respiratory chain, a key component in energy metabolism. Q203 blocks growth of Mycobacterium tuberculosis at nanomolar concentrations, however, it fails to actually kill the bacteria, which may limit the clinical applicability of this candidate drug. In this report we show that inhibition of cytochrome bd, a parallel branch of the mycobacterial respiratory chain, by aurachin D invoked bactericidal activity of Q203. In biochemical assays using inverted membrane vesicles from Mycobacterium tuberculosis and Mycobacterium smegmatis we found that inhibition of respiratory chain activity by Q203 was incomplete, but could be enhanced by inactivation of cytochrome bd, either by genetic knock-out or by inhibition with aurachin D. These results indicate that simultaneously targeting the cytochrome bcc and the cytochrome bd branch of the mycobacterial respiratory chain may turn out as effective strategy for combating M. tuberculosis.

Cement augmentation of humeral head screws reduces early implant-related complications after locked plating of proximal humeral fractures

Background

Cement augmentation (CA) of humeral head screws in locked plating of proximal humeral fractures (PHF) was found to be biomechanically beneficial. However, clinical outcomes of this treatment have not been well evaluated to date.

Objectives

To assess outcomes of locked plating of PHF with additional CA and to compare them with outcomes of conventional locked plating without CA.

Methods

24 patients (mean age, 74.2 ± 10.1 years; 22 female) with displaced PHF were prospectively enrolled and treated with locked plating and additional CA. The Constant score (CS), the Simple Shoulder Test (SST), and the Simple Shoulder Value (SSV) were assessed 3 and 12 months postoperatively. Fracture healing and potential complications were evaluated on postoperative radiographs. The CS and complications were compared with the outcomes of a matched group of 24 patients (mean age, 73.9 ± 9.4 years; 22 female) with locked plating of displaced PHF without CA.

Results

At the 3‑month follow-up, the mean CS was 59.9 ± 15.6 points, the mean SST was 7.5 ± 2.7 points, and the mean SSV was 63.9 ± 21.7%. All scores significantly improved by the 12-month follow-up (p < 0.05; CS, 72.9 ± 17.7; SST, 9.2 ± 3.2; SSV, 77.2 ± 17.3%). There were two cases (8%) of biological complications (n = 1 varus malunion and n = 1 humeral head necrosis). Compared with locked plating without CA, no significant differences were observed between the CS at the 3‑ (57.8 ± 13.4 points; p = 0.62) and 12-month (73.0 ± 12.8 points; p = 0.99) follow-up. However, patients without CA had a significantly increased risk of early loss of reduction and articular screw perforation (p = 0.037).

Conclusion

Locked plating of proximal humeral fractures with trauma cement augmentation of humeral head screws could be translated from the ex-vivo lab setting into the clinical situation without additional complications. Locked plating of displaced PHF with additional cement augmentation showed similar clinical outcomes but reduced the rate of early implant-related complications compared to locked plating without additional CA.

Neurocognitive deficits in schizophrenia. Are we making mountains out of molehills?

BACKGROUND

Most original studies and all meta-analyses conducted to date converge on the conclusion that patients with schizophrenia display rather generalized neurocognitive deficits. For the present study, we reopen this seemingly closed chapter and examine whether important influences, such as lack of motivation and negative attitudes towards cognitive assessment, result in poorer secondary neuropsychological performance.

METHOD

A sample of 50 patients with an established diagnosis of schizophrenia were tested for routine neurocognitive assessment and compared to 60 nonclinical volunteers. Before and after the assessment, subjective momentary influences were examined (e.g. motivation, concerns about assessment, fear about poor outcome) for their impact on performance using a new questionnaire called the Momentary Influences, Attitudes and Motivation Impact (MIAMI) on Cognitive Performance Scale.

RESULTS

As expected, patients performed significantly worse than controls on all neurocognitive domains tested (large effect size, on average). However, patients also displayed more subjective momentary impairment, as well as more fears about the outcome and less motivation than controls. Mediation analyses indicated that these influences contributed to (secondary) poorer neurocognitive performance. Differences in neurocognitive scores shrank to a medium effect size, on average, when MIAMI scores were accounted for.

CONCLUSIONS

The data argue that performance on measures of neurocognition in schizophrenia are to a considerable extent due to secondary factors. Poor motivation, fears and momentary impairments distinguished patients from controls and these variables heavily impacted performance. Before concluding that neurocognitive deficits in psychiatric patients are present, clinicians should take these confounding influences into account. Although patients with schizophrenia achieved, on average, worse test scores than controls, a large subgroup displayed spared performance.

A fluorescence-based reporter for monitoring expression of mycobacterial cytochrome bd in response to antibacterials and during infection

Cytochrome bd is a component of the oxidative phosphorylation pathway in many Gram-positive and Gram-negative bacteria. Next to its role as a terminal oxidase in the respiratory chain this enzyme plays an important role as a survival factor in the bacterial stress response. In Mycobacterium tuberculosis and related mycobacterial strains, cytochrome bd is an important component of the defense system against antibacterial drugs. In this report we describe and evaluate an mCherry-based fluorescent reporter for detection of cytochrome bd expression in Mycobacterium marinum. Cytochrome bd was induced by mycolic acid biosynthesis inhibitors such as isoniazid and most prominently by drugs targeting oxidative phosphorylation. We observed no induction by inhibitors of protein-, DNA- or RNA-synthesis. The constructed expression reporter was suitable for monitoring mycobacterial cytochrome bd expression during mouse macrophage infection and in a zebrafish embryo infection model when using Mycobacterium marinum. Interestingly, in both these infection models cytochrome bd levels were considerably higher than during in vitro culturing of M. marinum. The expression reporter described here can be a valuable tool for elucidating the role of cytochrome bd as a survival factor.

[Injuries of the acromioclavicular joint: Hook plate versus arthroscopy]

Acute acromioclavicular (AC) joint injuries are common in clinical practice. The hook plate is a well-established conventional operative treatment option for high grade instability; however, arthroscopically-assisted flexible double button techniques are increasingly being used. Both procedures lead to good or excellent results. The advantages of the hook plate are the simple surgical technique and the possibility of an early functional aftercare. The minimally invasive one-step procedure with the possibility of identification and treatment of frequently concomitant glenohumeral pathologies is advantageous for the arthroscopic technique but mobilization is more restrictive. Available comparative studies have shown no significant clinical differences but a tendency towards better results with a higher degree of acceptance among patients for the arthroscopic and minimally invasive non-rigid double button procedures.

MreB-Dependent Organization of the E. coli Cytoplasmic Membrane Controls Membrane Protein Diffusion

The functional organization of prokaryotic cell membranes, which is essential for many cellular processes, has been challenging to analyze due to the small size and nonflat geometry of bacterial cells. Here, we use single-molecule fluorescence microscopy and three-dimensional quantitative analyses in live Escherichia coli to demonstrate that its cytoplasmic membrane contains microdomains with distinct physical properties. We show that the stability of these microdomains depends on the integrity of the MreB cytoskeletal network underneath the membrane. We explore how the interplay between cytoskeleton and membrane affects trans-membrane protein (TMP) diffusion and reveal that the mobility of the TMPs tested is subdiffusive, most likely caused by confinement of TMP mobility by the submembranous MreB network. Our findings demonstrate that the dynamic architecture of prokaryotic cell membranes is controlled by the MreB cytoskeleton and regulates the mobility of TMPs.

Synthesis, characterization and biological activity of fluorescently labeled bedaquiline analogues

Labeling the tuberculosis drug bedaquiline with a fluorescent alkynyl-BODIPY moiety does not disrupt its antibacterial properties.

Is there any advantage in placing an additional calcar screw in locked nailing of proximal humeral fractures?

BACKGROUND

The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck.

HYPOTHESIS

The additional calcar screw improves stiffness and failure load.

METHODS

Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05).

RESULTS

No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases.

DISCUSSION

The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.

The cytochrome bd-type quinol oxidase is important for survival of Mycobacterium smegmatis under peroxide and antibiotic-induced stress

Targeting respiration and ATP synthesis has received strong interest as a new strategy for combatting drug-resistant Mycobacterium tuberculosis. Mycobacteria employ a respiratory chain terminating with two branches. One of the branches includes a cytochrome bc₁ complex and an aa₃-type cytochrome c oxidase while the other branch terminates with a cytochrome bd-type quinol oxidase. In this communication we show that genetic inactivation of cytochrome bd, but not of cytochrome bc₁, enhances the susceptibility of Mycobacterium smegmatis to hydrogen peroxide and antibiotic-induced stress. The type-II NADH dehydrogenase effector clofazimine and the ATP synthase inhibitor bedaquiline were bacteriostatic against wild-type M. smegmatis, but strongly bactericidal against a cytochrome bd mutant. We also demonstrated that the quinone-analog aurachin D inhibited mycobacterial cytochrome bd at sub-micromolar concentrations. Our results identify cytochrome bd as a key survival factor in M. smegmatis during antibiotic stress. Targeting the cytochrome bd respiratory branch therefore appears to be a promising strategy that may enhance the bactericidal activity of existing tuberculosis drugs.

[Suprapectoral mini-open biceps tenodesis - functional and sonographic results]

BACKGROUND

Aim of this study was to evaluate the effectiveness of a suprapectoral mini-open tenodesis of the long head of the biceps (LHB) tendon with ultrasound assessment. Secondary aim was to compare the results of an extraosseous fixation (group I) to those of an intraosseous fixation technique (group II).

PATIENTS AND METHODS

25 patients (10 female, 15 male) aged 54 ± 8 (36 to 68) years were followed-up 21 ± 4.7 (13 to 32) months postoperatively. Tenodesis fixation was extraosseous in 12 (group I) and intraosseous in 13 patients (group II). Preoperative shoulder function and intraoperative findings were recorded. At the time of follow-up the fixation of the biceps tendon was evaluated by ultrasound examination. Furthermore, the shoulder function, the simple shoulder test (SST), the Constant-Murley score (CMS) and the "long head of the biceps (LHB) score" were assessed.

RESULTS

Failure of tenodesis fixation was observed in 3/12 cases (25 %) of group I and 1/13 cases (8 %) of group II. Shoulder flexion (p < 0.001), abduction (p < 0.001), external rotation (p < 0.001) and the pain level (p < 0.001) improved significantly compared to the preoperative status. At time of follow-up the CMS averaged 79.4 ± 13 points, the age and gender related CMS averaged 95.7 ± 16.4 %. Mean SST was 10.6 ± 2.1 points. No significant difference (p = 0.064) could be observed between the LHB of the affected (88.1 ± 9.7) versus the non-affected shoulder (92.7 ± 13.6 points). Age and gender related CMS (p = 0.96), LHB score (p = 0.16) and SST (p = 0.94) of both groups revealed no significant differences.

CONCLUSION

The intraosseous fixation technique seems favourable with less fixation failure compared to the extraosseous suspension technique. The suprapectoral mini-open tenodesis of the LHB is a valuable alternative tenodesis technique with good to excellent clinical results.

[Corrective osteosynthesis of proximal humeral fractures. Technique and prospective results]

BACKGROUND

Fracture sequelae of proximal humeral fractures arise following nonoperative and operative forms of treatment. Due to a painful restricted range of motion, in most cases shoulder prostheses are implanted. There is a need for joint-preserving alternatives especially for younger patients.

OBJECTIVES

The aim of this study was to evaluate the surgical techniques and prospective results of fracture sequelae of proximal humeral fractures following corrective osteosynthesis.

MATERIAL AND METHODS

A total of 11 patients (4 female) with an average age of 53 years (range 29-71 years) and a mean follow-up of 19.5 months were included prospectively. The preoperative and postoperative ranges of motion of the affected shoulder were compared by statistical means. At the time of follow-up the constant score (CS), the simple shoulder test (SST) and the simple shoulder value (SSV) were assessed.

RESULTS

Fracture sequelae were classified as type II in four patients, as type III in two and as type IV in five patients using the Boileau classification. Shoulder flexion (p = 0.006), abduction (p = 0.003) and external rotation (p = 0.02) improved significantly in the postoperative course. The mean age and gender-adapted CS was 74.8 ± 19.9 % at the time of follow-up, 10.1 out of 12 points were reached in the SST and the mean SSV was 77 %.

CONCLUSION

Corrective osteosynthesis of fracture sequelae (Boileau types II-IV) of proximal humeral fractures appears to be a good alternative to implantation of shoulder prostheses, especially in younger patients (< 60 years of age).

ATP synthase in mycobacteria: special features and implications for a function as drug target

ATP synthase is a ubiquitous enzyme that is largely conserved across the kingdoms of life. This conservation is in accordance with its central role in chemiosmotic energy conversion, a pathway utilized by far by most living cells. On the other hand, in particular pathogenic bacteria whilst employing ATP synthase have to deal with energetically unfavorable conditions such as low oxygen tensions in the human host, e.g. Mycobacterium tuberculosis can survive in human macrophages for an extended time. It is well conceivable that such ATP synthases may carry idiosyncratic features that contribute to efficient ATP production. In this review genetic and biochemical data on mycobacterial ATP synthase are discussed in terms of rotary catalysis, stator composition, and regulation of activity. ATP synthase in mycobacteria is of particular interest as this enzyme has been validated as a target for promising new antibacterial drugs. A deeper understanding of the working of mycobacterial ATP synthase and its atypical features can provide insight in adaptations of bacterial energy metabolism. Moreover, pinpointing and understanding critical differences as compared with human ATP synthase may provide input for the design and development of selective ATP synthase inhibitors as antibacterials. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.

Influence of rupture patterns of the medial patellofemoral ligament (MPFL) on the outcome after operative treatment of traumatic patellar dislocation

PURPOSE

Patellar dislocation usually occurs to the lateral side, leading to ruptures of the medial patellofemoral ligament (MPFL) in about 90 % of all cases. Reliable prognostic factors for the stability of the patellofemoral joint after MPFL surgery and satisfaction of the patient have not been established as yet.

METHODS

This multicentric study retrospectively included 40 patients with a mean age of 22.4 ± 8.1 years (range 9-48) from 5 German Trauma Departments with first-time traumatic patellar dislocation and operative treatment. Surgery was limited to soft tissue repairs, and a preoperative magnetic resonance imaging (MRI) was performed in all cases. Evaluation of the MRI included sulcus angle, dysplasia of the trochlea, depth and facet asymmetry of the trochlea, Insall-Salvati index, Tibial tuberosity to trochlear groove (TTTG) distance, and rupture patterns of the MPFL. Patients were interrogated after 2 years about recurrent dislocation, satisfaction, and the Kujala score.

RESULTS

Trochlea facet asymmetry was significantly lower in patients with redislocation (23.5 ± 18.8) than in patients without redislocation (43.1 ± 16.5, p = 0.03). Patients with a patellar-based rupture were significantly younger (19.5 ± 7.2 years) than patients without patellar-based rupture (25.4 ± 8.1 years, p < 0.02). Patients with femoral-based ruptures were significantly older (25.7 ± 9.2 years) than patients without femoral-based rupture (19.7 ± 6.1 years, p < 0.02), and had a significantly higher TTTG distance (10.2 ± 6.9 vs. 4.5 ± 5.5, p < 0.02). Patients with incomplete ruptures of the MPFL had a significantly lower Insall-Salvati index (1.2 ± 0.2 vs. 1.4 ± 0.2, p = 0.05). The Kujala score in patients with redislocations was significantly lower (81.0 ± 10.5 points) than in patients without redislocation (91.9 ± 9.2 points, p < 0.02).

CONCLUSION

Younger patients more often sustain patellar-based ruptures following first-time traumatic patella dislocation, while older patients more often sustain femoral-based ruptures of the MPFL. Incomplete MPFL ruptures are correlated with lower Insall-Salvati indices. Low trochlear facet asymmetry is correlated with higher rates of redislocation. These results may be of relevance for the operative and postoperative treatment in the future.

LEVEL OF EVIDENCE

Prognostic study, Level IV.

Operative vs conservative treatment of traumatic patellar dislocation: results of a prospective randomized controlled clinical trial

INTRODUCTION

Patellar dislocation is a common knee injury with mainly lateral dislocations, leading to ruptures of the medial patellofemoral ligament in most of the cases. Even though several prognostic factors for patellofemoral instability have been identified so far, the appropriate therapy for patients with patellar dislocation remains a controversial issue. The purpose of this study was to compare the outcome after conservative or operative treatment in patients after first-time patellar dislocation.

PATIENTS AND METHODS

This randomized controlled clinical trial was designed multicentric including patients from six German orthopaedic and trauma departments. Twenty patients with a mean age of 24.6 years with first-time traumatic patella dislocation were included and randomized into either a conservative arm or an operative arm. Plain X-ray images of the knee joint (a.p. and lateral view and tangential view of both patellae) were performed in all cases prior to therapy to exclude osteochondral fragments requiring refixation. An MRI was recommended, but not compulsory. Patients were consulted after 6, 12, and 24 months with a questionnaire including the criteria of the Kujala score, recurrent dislocation, and satisfaction.

RESULTS

The mean Kujala score of the conservative vs operative treatment group was 78.6 vs 80.3 after 6 months (p = 0.842), 79.9 vs 88.9 after 12 months (p = 0.165), and 81.3 vs 87.5 after 24 months (p = 0.339). Redislocation rate after 24 months was 37.5 % in the conservative group and 16.7 % in the operative group (p = 0.347). Due to the small number of patients that could be included, no significant difference between the groups could be detected. We see a tendency towards better results after operative treatment.

CONCLUSION

Our multicentric prospective randomized controlled trial revealed no significant difference between conservative and operative treatment for patients after first-time traumatic patellar dislocation. However, a tendency towards a better Kujala score and lower redislocation rates for patients with operative treatment was observed. The small number of patients is a limiting factor of the study, leading to results without statistical significance. A meta-analysis including other study's level I data is desirable for the future.

[Shoulder stiffness]

Primary shoulder stiffness is idiopathic. Due to coincidence with other diseases, a systemic genesis with hormonal influence is discussed. The result of chronic inflammation with fibroblastic proliferation is a fibrotic capsule, atrophy of ligaments, and muscular dysbalance. The main symptom is painful restricted passive and active shoulder motion. There is a high rate of unsatisfactory courses. Therapy depends on the phase and duration of shoulder stiffness. Primary treatment of choice is oral steroid therapy, followed by physical and physiotherapy. Steroids can be applied intraarticular, as an alternative. If conservative treatment fails after a period of 6 months, arthroscopic arthrolysis is indicated. Secondary shoulder stiffness often results from traumatization or operation of the shoulder. Primary treatment is also conservative, but operative intervention should be performed early after unsuccessful therapy. Intensive, passive mobilization is necessary after arthrolysis.

[Subscapularis tendon lesions. Anatomy, diagnosis and importance of arthroscopic treatment]

The subscapularis tendon is involved in up to 43% of arthroscopically treated rotator cuff lesions. Due to the close anatomic relationship, participation of the long head of the biceps and supraspinatus tendon is common. Subscapularis tendon lesions are often not primary diagnosed correctly. Using specific clinical tests and modern sectional imaging, the percentage of correct diagnoses can be increased. Convincing clinical results, advantages of minimally invasive surgery, and superior visualization compared to the open approach argue for arthroscopic treatment of subscapularis lesions. Awareness of the footprint allows anatomic reconstruction. In case of planned open treatment, arthroscopy should precede as particularly articular-sided lesions might be missed otherwise.

[Comparison of results after primary and secondary shoulder arthroplasty for proximal humeral fractures]

BACKGROUND

The purpose of this retrospective cohort study was to evaluate, compare and discuss the results and complications after primary and secondary shoulder arthoplasty in proximal humeral fractures.

PATIENTS AND METHODS

Thirteen consecutive patients (mean 76 years [range, 65-85] years) were at a mean of 29 (8-37) months after primary humeral head replacement (group 1), and 15 patients (mean 74 years [range, 43-80] years) at a mean of 18 (7-36) months after secondary shoulder arthoplasty (n = 8 anatomic prostheses, n = 7 reversed prostheses) due to complications/fracture sequelae (group 2) examined clinically and radiologically according to a standardised follow-up protocol. Patient satisfaction, the simple shoulder test (SST), the American shoulder elbow score (ASES) as well as the Constant score (CS) were assessed, and radiological parameters as well as complications analysed.

RESULTS

85 % of patients in group 1 and 73 % in group 2 were satisfied with the results. The SST did not show a significant difference between both groups. The adjusted ASES did not differ significantly with 70 (27-95)% in group 1 and 73 (28-100)% in group 2, as well as the adjusted CS with a mean of 53 (27-83)% in group 1 and of 49 (27-87)% in group 2. Radiological analysis resulted in a correctly centred prosthesis in 6/13 patients, and healed tuberosities in 7/13 of group 1. In group 2 4/8 anatomic prostheses were centered and 7/8 showed healed tuberosities. In the subgroup of the reversed prostheses 6/7 were centered, 3/7 patients had an inferior "notching". The rate of complications and revisions were 2/13 (15 %) in group 1 and 1/15 (7 %) in group 2.

CONCLUSION

In summary, the functional results did not differ significantly between primary and secondary shoulder arthroplasty after proximal humeral fractures. The relatively low expectation of elderly patients is reflected in a high rate of patient satisfaction in spite of moderate functional results. The primary humeral head replacement showed higher rates of complications and revisions compared to secondary arthroplasty.

The hydrophobic core of twin-arginine signal sequences orchestrates specific binding to Tat-pathway related chaperones

Redox enzyme maturation proteins (REMPs) bind pre-proteins destined for translocation across the bacterial cytoplasmic membrane via the twin-arginine translocation system and enable the enzymatic incorporation of complex cofactors. Most REMPs recognize one specific pre-protein. The recognition site usually resides in the N-terminal signal sequence. REMP binding protects signal peptides against degradation by proteases. REMPs are also believed to prevent binding of immature pre-proteins to the translocon. The main aim of this work was to better understand the interaction between REMPs and substrate signal sequences. Two REMPs were investigated: DmsD (specific for dimethylsulfoxide reductase, DmsA) and TorD (specific for trimethylamine N-oxide reductase, TorA). Green fluorescent protein (GFP) was genetically fused behind the signal sequences of TorA and DmsA. This ensures native behavior of the respective signal sequence and excludes any effects mediated by the mature domain of the pre-protein. Surface plasmon resonance analysis revealed that these chimeric pre-proteins specifically bind to the cognate REMP. Furthermore, the region of the signal sequence that is responsible for specific binding to the corresponding REMP was identified by creating region-swapped chimeric signal sequences, containing parts of both the TorA and DmsA signal sequences. Surprisingly, specificity is not encoded in the highly variable positively charged N-terminal region of the signal sequence, but in the more similar hydrophobic C-terminal parts. Interestingly, binding of DmsD to its model substrate reduced membrane binding of the pre-protein. This property could link REMP-signal peptide binding to its reported proofreading function.

Probing the interaction of the diarylquinoline TMC207 with its target mycobacterial ATP synthase

Infections with Mycobacterium tuberculosis are substantially increasing on a worldwide scale and new antibiotics are urgently needed to combat concomitantly emerging drug-resistant mycobacterial strains. The diarylquinoline TMC207 is a highly promising drug candidate for treatment of tuberculosis. This compound kills M. tuberculosis by binding to a new target, mycobacterial ATP synthase. In this study we used biochemical assays and binding studies to characterize the interaction between TMC207 and ATP synthase. We show that TMC207 acts independent of the proton motive force and does not compete with protons for a common binding site. The drug is active on mycobacterial ATP synthesis at neutral and acidic pH with no significant change in affinity between pH 5.25 and pH 7.5, indicating that the protonated form of TMC207 is the active drug entity. The interaction of TMC207 with ATP synthase can be explained by a one-site binding mechanism, the drug molecule thus binds to a defined binding site on ATP synthase. TMC207 affinity for its target decreases with increasing ionic strength, suggesting that electrostatic forces play a significant role in drug binding. Our results are consistent with previous docking studies and provide experimental support for a predicted function of TMC207 in mimicking key residues in the proton transfer chain and blocking rotary movement of subunit c during catalysis. Furthermore, the high affinity of TMC207 at low proton motive force and low pH values may in part explain the exceptional ability of this compound to efficiently kill mycobacteria in different microenvironments.

[How to become a trauma surgeon: analysis of the current situation and concepts for career development in the new common field of orthopaedics and trauma surgery--part I]

The lack of clinical residents especially in the surgical domains, including orthopaedics and trauma surgery, is not only omnipresent but also a topic of lively discussions. This lack originates from sociopolitical and healthcare policy issues as well as from a loss of attractiveness of all surgical disciplines. The loss is caused by the high workload and disadvantageous working hours especially in those disciplines with a high rate of emergencies, e.g. trauma surgery. Moreover, it is caused by the poorly structured and unpredictable period of residency. In order to anticipate the bottleneck in supply due to the lack of trainees, a number of structural and contextual measures have to be taken to improve both undergraduate und postgraduate surgical training. Due to the numerous facets of the topic the first part of this analysis refers to the period until the trainee decides on the field of training.A basic insight into the field of orthopaedics and trauma surgery can already be offered far before the period of medical studies itself. During undergraduate medical education the existing structures should be modified, the characteristics of the discipline should be emphasized and the charm of combining theory and practical skills should be highlighted in order to enhance student's perception of the discipline. This might begin during preclinical training and should be continued throughout clinical training and elective courses (basic wound care, TEAM approach, AO course for students and seminars for M.D. candidates). Contextual and structural improvements of the practical year are indispensable to arouse students' interest in our discipline. These options conjoined with the actual offers for students provided by our scientific society, such as guided tours during the annual congress, travelling grants and the recently inaugurated summer school, might provide the basis for clearly structured information and offer a distinct stimulus to apply for residency in our field.

ATP synthase in slow- and fast-growing mycobacteria is active in ATP synthesis and blocked in ATP hydrolysis direction

ATP synthase is a validated drug target for the treatment of tuberculosis, and ATP synthase inhibitors are promising candidate drugs for the treatment of infections caused by other slow-growing mycobacteria, such as Mycobacterium leprae and Mycobacterium ulcerans. ATP synthase is an essential enzyme in the energy metabolism of Mycobacterium tuberculosis; however, no biochemical data are available to characterize the role of ATP synthase in slow-growing mycobacterial strains. Here, we show that inverted membrane vesicles from the slow-growing model strain Mycobacterium bovis BCG are active in ATP synthesis, but ATP synthase displays no detectable ATP hydrolysis activity and does not set up a proton-motive force (PMF) using ATP as a substrate. Treatment with methanol as well as PMF activation unmasked the ATP hydrolysis activity, indicating that the intrinsic subunit ɛ and inhibitory ADP are responsible for the suppression of hydrolytic activity. These results suggest that the enzyme is needed for the synthesis of ATP, not for the maintenance of the PMF. For the development of new antimycobacterial drugs acting on ATP synthase, screening for ATP synthesis inhibitors, but not for ATP hydrolysis blockers, can be regarded as a promising strategy.

[Early functional treatment and full weight-bearing of surgically treated isolated ankle fractures in the elderly]

QUESTION

Fractures of the ankle joint belong to the most often occurring injuries. The aftercare in plaster lasts several weeks and is problematic especially in elderly patients.

METHODS

In a retrospective study patients over the age of 50 years who underwent surgical treatment of ankle fractures and early functional mobilization were examined in a follow-up. The range of motion, the circumferential measurements and the radiological course were examined by comparing preoperative and postoperative X-ray images after 13-24 months. The subjective results were collected using the Olerud-Molander score (OMS).

RESULTS

A total of 30 out of 42 patients who qualified for the follow-up were included in the study. The distribution of the gender was equal as was the right/left distribution and the mean age was 68 years. The magnitude of movement and comparison between the two sides showed no significant differences. The average score for subjective satisfaction was 90 in the OMS. The radiological results showed few changes and no deviations from the axis. No redislocations or implant fractures could be observed. Early functional full weight-bearing showed satisfactory preliminary results.

CONCLUSION

This treatment concept can be recommended because patient comfort is increased and the risk of immobilization is excluded.

[Proximal humeral fracture]

Fractures of the proximal humerus are very common in elderly people with an increasing incidence. Complex fracture-patterns are observed. For radiological examination x-rays in 2 planes are mandatory. Often an additive CT-scan can be useful for a better understanding of the whole fracture-character. Limits of accepted fracture displacement decrease and reconstructive surgery is induced more frequently. Advantageous are the functional after-treatment and the early reintegration to the activities of daily living after osteosyntheses. Locking nail- and platesystems are competing standard-implants, whereas plate osteosynthesis is preferred in higher-part-fractures. Non-reconstructable fractures should be treated with a primary head replacement, in the form of a reverse prosthesis in patients older than 75 years.

Arthroscopic treatment of multidirectional glenohumeral instability in young overhead athletes

Purpose:

This prospective case series evaluates the outcome, and the return to sports of young overhead athletes with a persistent, symptomatic multidirectional instability (MDI) with hyperlaxity type Gerber B5 treated with an arthroscopic anteroposteroinferior capsular plication and rotator interval closure.

Methods:

9 young overhead athletes (10 shoulders) with the rare diagnosis of MDI (Gerber B5) and an indication for operative treatment, after a failed physiotherapy program were physically examined 3, 6 and 12 months postoperatively by a physical examination, and got a final phone interview after median 39 months.

Results:

At the final follow-up all patients were satisfied; Rowe Score showed 7 “excellent” and “good” results; Constant Score was “excellent” and “good” in 6, and “fair” in 1 patient. 7/9 returned to their previous sports, 3/9 at a reduced level.

Conclusion:

Symptomatic MDI requires an individual indication for surgical treatment after a primary conservative treatment. The described arthroscopic technique stabilizes glenohumeral joint. A return to overhead sports is possible but often at a reduced level; returning to high-performance sports cannot be recommended because of the high risk of reinstability.

Two-stimuli manipulation of a biological motor

F1-ATPase is an enzyme acting as a rotary nano-motor. During catalysis subunits of this enzyme complex rotate relative to other parts of the enzyme. Here we demonstrate that the combination of two input stimuli causes stop of motor rotation. Application of either individual stimulus did not significantly influence motor motion. These findings may contribute to the development of logic gates using single biological motor molecules.

[Primary hemiarthroplasty in proximal humerus fractures]

The surgical treatment of complex proximal humerus fractures is still a great challenge. Not all fracture types can be successfully reconstructed. Indications for a primary joint replacement arise from critical fracture patterns and defined predictors of ischemia in the elderly (age >60 years). If good functional results are to be achieved a soft-tissue-preserving surgical technique, secure tuberosity attachment and accurate soft tissue balancing of the rotator cuff, correct restoration of height, retrotorsion and offset, and appropriate physiotherapy afterwards are essential. In multicentre studies in patients who had undergone primary hemoarthroplasty average Constant-Murlay Scores of 56.0-73.5 point were recorded. At follow-up, 79% of the patients reported only mild pain or none at all, and the ROM was acceptable (41.9% anteversion >90 degrees , 34.7% abduction >90 degrees ). Generally, subjective evaluations were much better than the objective results.The incidence of complications after humeral head replacement is still relatively high, whereas the 10-year survival rate of shoulder hemiarthroplasties has been found in a recent study to be 100%.

Diarylquinolines target subunit c of mycobacterial ATP synthase

The diarylquinoline R207910 (TMC207) is a promising candidate in clinical development for the treatment of tuberculosis. Though R207910-resistant mycobacteria bear mutations in ATP synthase, the compound's precise target is not known. Here we establish by genetic, biochemical and binding assays that the oligomeric subunit c (AtpE) of ATP synthase is the target of R207910. Thus targeting energy metabolism is a new, promising approach for antibacterial drug discovery.

Komplikationsmanagement nach winkelstabiler Plattenosteosynthese am proximalen Humerus

PURPOSE

In this prospective study, complications observed after angularly stable proximal humerus plate fixation (locking proximal humerus plate) were analysed by deriving specific therapies.

PATIENTS

Fifty patients (median age 65 years, range 25-84 years, 39 female, 11 male) with displaced proximal humerus fractures (seven single, 36 double, and seven triple fractures) were evaluated 3, 6, and 12 months after angularly stable plate fixation using a standard protocol.

RESULTS

Age- and gender-matched median constant scores 12 months postoperatively showed for the three fracture types 86, 87, and 55 points and complication rates of 14, 19, and 100%, respectively. There were seven primary and seven secondary implant displacements, five humeral head necroses, four osseous malalignments, two nonunions, two deep infections, and one heterotopic ossification. Nine reoperations were required in six patients: implant removal (n=3), reosteosynthesis (n=2), revision because of nonunion (n=2), and deep infection (n=2).

CONCLUSIONS

Differentiated analysis of complications and the development of specific prevention and therapeutic strategies considering surgical technique, implant, fracture morphology, and humeral head perfusion minimize the rate of complications observed after angularly stable locking proximal humerus plate fixation.

The V-ATPase from etiolated barley (Hordeum vulgare L.) shoots is activated by blue light and interacts with 14-3-3 proteins

The vacuolar H(+)-ATPase (V-ATPase) is a key enzyme that controls the electrochemical proton potential across endomembranes. Although evidence suggests that V-ATPase is important for photo-morphogenesis, little is known about short-term regulation of V-ATPase upon initiation of the photo-morphogenetic programme by exposure of dark-grown plants to light. In this study, etiolated coleoptiles were given a short blue light treatment and V-ATPase characteristics were determined. The effectiveness of the light treatment was assessed by means of fusicoccin binding to the plasma membrane; this increased 5-fold. The short light treatment also induced a 2-fold to 3-fold increase in the hydrolytic activity of V-ATPase. Members of the 14-3-3 protein family are involved in both blue light perception and the subsequent activation of the P-type ATPase. We provide evidence that 14-3-3 proteins specifically interact with the catalytic A-subunit of the V-ATPase. First, the isolated V1-part of the V-ATPase co-purifies with 14-3-3 on a gel filtration column. Secondly, in an overlay experiment, 14-3-3 interacts with a 68 kDa band that was identified as the V1 A-subunit by mass spectrometry. Thirdly, in 14-3-3 affinity chromatography, both A- and B-subunits of the catalytic moiety of the V-ATPase were identified by matrix-assisted laser desorption ionization tandem time of flight mass spectrometry (MALDI TOF/TOF MS) as 14-3-3-interacting proteins. It was shown that the A-subunit can be phosphorylated in vitro by a tonoplast-bound kinase, whose properties are affected by blue light. Taken together, the data show that besides the P- and F-type H(+)-ATPases, the V-type H(+)-ATPase also interacts with 14-3-3 proteins.

Die Candida-albicans-induzierte Spondylodiszitis der Halswirbelsäule bei einem polytraumatisierten Patienten

With the increasing occurrence of predisposing factors, invasive candidiasis is being diagnosed more frequently. Based on a review of only a few previous reported cases, we describe and discuss the unusual case of candidal cervical spondylodiscitis in a 36 year old man who had sustained a polytrauma, complicated through a Candida albicans pneumonia. The main symptom was disabling neck pain. Clinical, laboratory and radiological findings were unspecific. The definitive diagnosis was determined by MRI imaging and biopsy. The early diagnosis and surgical treatment with a sufficient debridement and stabilisation of the affected segment combined with a prolonged antifungal therapy lead to good results.

Welche Vorteile bietet die volare Plattenosteosynthese gegenüber der Kirschner-Drahtstabilisierung bei distalen Radiusextensionsfrakturen des alten Menschen?

PURPOSE

The purpose of this retrospective study was to compare the outcome of open reduction and internal fixation (ORIF) followed immediately by physiotherapy and of percutaneous K-wire-fixation and casting for unstable distal radius fractures in elderly patients, considering the results both in general, for all such fractures, and selectively for A3 and C2 fractures.

METHODS

Follow-up examinations were performed 26 (18-48) months after surgery in 43 patients (median age 67 (60-83) years) treated with K-wire fixation and 9 (5-17) months after surgery in 46 patients (median age 76 (60-90) years) treated with ORIF, and the outcome of each was recorded as Disabilities of the Arm, Shoulder and Hand (DASH), Gartland-Werley and Castaing scores; the radiological loss of correction was also assessed. Statistical analysis was performed first without reference to the specific type of fracture for the K-wire- and the total ORIF -groups, and then selectively for A3 and C2 -fractures only; in the second analysis the patients were divided into three groups: KD, ORIF with and ORIF without angular stability.

RESULTS

The Garland-Werley and Castaing scores do not indicate any significant difference between the procedures specified. According to the Garland-Werley score 37 patients (86%) treated by K-wire fixation and 39 (85%) treated by ORIF achieved "excellent" and "good" results; according to the Castaing score there were 33 (77%) "good" results after K-wire fixation and 34 (74%) good results after ORIF. The radiological loss of correction (K-wire fixation/ORIF) as measured by the radial inclination (median 2/2.5 degrees), the palmar tilt (median 3/5 degrees) and the radial shortening (median 1/1 degrees mm) do not differ significantly. Suboptimal radiological results do not always correlate with results that are only "fair" or "poor". The non-fracture-specific DASH score suggests a higher degree of patient satisfaction after K-wire fixation (7 [0-87] points) than after ORIF (17 [0-82] points), which is not confirmed by fracture-specific evaluation. There is a significantly earlier return to the "activities of daily living" (4 as against 8 weeks) after ORIF.

CONCLUSION

All the treatments compared are suitable for the treatment of A3 and C2 fractures. The important advantages of ORIF are the early functional physiotherapy without casting and without obligatory second surgery and the earlier return to "activities of daily living", which are all of decisive importance for older patients, who are the ones most frequently affected.