Carbon signaling protein SbtB possesses atypical redox-regulated apyrase activity to facilitate regulation of bicarbonate transporter SbtA

The PII superfamily consists of widespread signal transduction proteins found in all domains of life. In addition to canonical PII proteins involved in C/N sensing, structurally similar PII-like proteins evolved to fulfill diverse, yet poorly understood cellular functions. In cyanobacteria, the bicarbonate transporter SbtA is co-transcribed with the conserved PII-like protein, SbtB, to augment intracellular inorganic carbon levels for efficient CO2 fixation. We identified SbtB as a sensor of various adenine nucleotides including the second messenger nucleotides cyclic AMP (cAMP) and c-di-AMP. Moreover, many SbtB proteins possess a C-terminal extension with a disulfide bridge of potential redox-regulatory function, which we call R-loop. Here, we reveal an unusual ATP/ADP apyrase (diphosphohydrolase) activity of SbtB that is controlled by the R-loop. We followed the sequence of hydrolysis reactions from ATP over ADP to AMP in crystallographic snapshots and unravel the structural mechanism by which changes of the R-loop redox state modulate apyrase activity. We further gathered evidence that this redox state is controlled by thioredoxin, suggesting that it is generally linked to cellular metabolism, which is supported by physiological alterations in site-specific mutants of the SbtB protein. Finally, we present a refined model of how SbtB regulates SbtA activity, in which both the apyrase activity and its redox regulation play a central role. This highlights SbtB as a central switch point in cyanobacterial cell physiology, integrating not only signals from the energy state (adenyl-nucleotide binding) and the carbon supply via cAMP binding but also from the day/night status reported by the C-terminal redox switch.

Prevalence of cardiac amyloidosis among cardiac- and non-cardiac patients undergoing echocardiography at a large university echo lab in Germany: a cohort study

Background

Cardiac amyloidosis (CA) is a progressive infiltrative cardiomyopathy that leads to severe heart failure and, once clinically relevant, poses a high mortality risk. Epidemiological data for CA are still sparse and heterogeneous, but urgently needed since novel therapies against ATTR-CA are now available.

Aim

We aimed to assess minimum prevalence rates of CA among cardiac and non-cardiac patients undergoing routine echocardiography in an echo lab of a large university clinic serving all medical specialities in central Germany.

Methods

We established a retro- and prospective database based on suspicious findings in echocardiography for all echocardiographic exams over an 8.5 year period (03/2013 and 09/2021). During this time, 41,375 patients underwent at least one echo exam. Indication for echos were mixed, and consisted of non-cardiac and cardiac patients with acute and chronic illnesses as well as screening exams (e.g. before major surgery or chemotherapy). Suspicious echocardiography were retrospectively analysed whether they underwent further diagnostic or if it remained an unproven suspicion (figure). All echos of suspicious cases were comprehensively re-analysed regarding novel surrogate parameters and indices for CA. Various clinical and laboratory parameters were collected.

Results

The mean age of the cohort of 41,375 patients was 65.1±15.8 years for the first or only echo examination with a slightly unbalanced gender distribution (45% female). The age distribution is shown in the table. While 128 patients were suspected, the diagnosis was falsified in 16 patients and proven in 47 patients (light chain n=16, ATTR n=31; figure). A substantial proportion of patients with suspicious echo received no further diagnostic work-up (N=65). Over the given time frame of 101 months, the prevalence of suspicious echocardiograms was 1 per 323 patients (or 31 per 10,000). The proven cases had a prevalence of 1 per 880 patients (or 11.3 per 10,000). Since ATTR-CA is a disease of the elderly, we saw a vanishingly small number of cases in persons younger than 70 years (table), whereas 90% of all CA patients were older than 70 years. At timing of diagnosis, AL-CA patients were almost 10 years younger compared to diagnosis of ATTR-CA (69.1±8.4 years vs. 77.4±8.5 years). In patients older than 80 years, the prevalence rate of ATTR-CA peaked with 22.6 cases per 10.000 patients (0.23%). The prevalence rate of ATTR-CA was roughly twice as high compared to AL-CA.

Conclusion

For the first time, an estimation of minimum prevalence rates for CA for a defined volume of echocardiograms in an all-comers population is provided. In a mixed population of a hospital of maximum care CA prevalence rate is much higher than expected. Awareness for this “rare” disease is needed, since routine echo exams can prompt suspicion in clinically silent or so far unrecognized CA cases.

Funding Acknowledgement

Type of funding sources: None.

Diurnal metabolic control in cyanobacteria requires perception of second messenger signaling molecule c-di-AMP by the carbon control protein SbtB

Because of their photosynthesis-dependent lifestyle, cyanobacteria evolved sophisticated regulatory mechanisms to adapt to oscillating day-night metabolic changes. How they coordinate the metabolic switch between autotrophic and glycogen-catabolic metabolism in light and darkness is poorly understood. Recently, c-di-AMP has been implicated in diurnal regulation, but its mode of action remains elusive. To unravel the signaling functions of c-di-AMP in cyanobacteria, we isolated c-di-AMP receptor proteins. Thereby, the carbon-sensor protein SbtB was identified as a major c-di-AMP receptor, which we confirmed biochemically and by x-ray crystallography. In search for the c-di-AMP signaling function of SbtB, we found that both SbtB and c-di-AMP cyclase–deficient mutants showed reduced diurnal growth and that c-di-AMP–bound SbtB interacts specifically with the glycogen-branching enzyme GlgB. Accordingly, both mutants displayed impaired glycogen synthesis during the day and impaired nighttime survival. Thus, the pivotal role of c-di-AMP in day-night acclimation can be attributed to SbtB-mediated regulation of glycogen metabolism.

Computational models in the service of X-ray and cryo-electron microscopy structure determination

Critical assessment of structure prediction (CASP) conducts community experiments to determine the state of the art in computing protein structure from amino acid sequence. The process relies on the experimental community providing information about not yet public or about to be solved structures, for use as targets. For some targets, the experimental structure is not solved in time for use in CASP. Calculated structure accuracy improved dramatically in this round, implying that models should now be much more useful for resolving many sorts of experimental difficulties. To test this, selected models for seven unsolved targets were provided to the experimental groups. These models were from the AlphaFold2 group, who overall submitted the most accurate predictions in CASP14. Four targets were solved with the aid of the models, and, additionally, the structure of an already solved target was improved. An a posteriori analysis showed that, in some cases, models from other groups would also be effective. This paper provides accounts of the successful application of models to structure determination, including molecular replacement for X-ray crystallography, backbone tracing and sequence positioning in a cryo-electron microscopy structure, and correction of local features. The results suggest that, in future, there will be greatly increased synergy between computational and experimental approaches to structure determination.

Clinical characteristics and haemodynamic state of patients undergoing interhospital transfer for postpartum haemorrhage: A study of a single-centre helicopter emergency medical service

OBJECTIVE

Uterine artery embolization is an attractive option for the management of postpartum haemorrhage, however it is not available in every hospital. We compared the clinical characteristics and haemodynamic state of patients with postpartum haemorrhage, before and after helicopter transfer to a tertiary hospital for possible uterine artery embolization. We also analysed whether the type of treatment could modify the outcome.

STUDY DESIGN

Between 1999 and 2019 in Switzerland, we retrospectively found 82 consecutive patients with postpartum haemorrhage who were transferred by a physician-staffed helicopter emergency medical service to the tertiary hospital for potential uterine artery embolization. The collected data included the type of delivery, estimated blood loss, shock index and blood lactate levels before transfer and at destination, uterine artery embolization rate and hospital mortality rate. Our primary outcome was to describe the clinical characteristics, outcomes and haemodynamic state of the patients with postpartum haemorrhage before and after helicopter transfer. Our secondary outcome was to report the treatments performed at the tertiary hospital. The collected data were analysed with Stata version 14 (Stata Corporation, College Station, TX, USA). Continuous data are compared by using the Student's t-test or the Mann-Whitney U test, as appropriate.

RESULTS

We included 69 patients. Postpartum haemorrhage occurred after vaginal delivery in 38 cases (55%). Blood loss prior to transfer exceeded 2 L in 34% of cases. The median shock index was 1 (IQR 0.8-1.1) before transfer and 0.9 (IQR 0.8-1.1) after transfer (p = 0.41). The median lactate level was 2.9 mmol/L (IQR 2.1-6.8) before, and 2.1 mmol/L (IQR 1.55-3.5) after transfer (p = 0.90). Forty-four patients underwent uterine artery embolization (64%), with an overall success rate of 93%. One patient died (1.4%), from a haemorrhagic shock of abdominal origin.

CONCLUSIONS

Interhospital helicopter transfer of patients with postpartum haemorrhage to a tertiary hospital seems to be safe in our setting, despite a significant proportion of patients exhibiting signs of haemodynamic instability. Decision criteria would be helpful to better guide choices regarding the transfer of patients with postpartum haemorrhage.

[Automatic load-distributing band CPR (AutoPulse™) in prone position, feasible?]

BACKGROUND

Due to SARS-CoV‑2 respiratory failure, prone positioning of patients with respiratory and hemodynamic instability has become a frequent intervention in intensive care units (ICUs), and even in patients undergoing transfer in an ambulance or helicopter. It has become increasingly important how to perform safe and effective CPR in prone position, achieving both an optimal outcome for the patient and optimal protection of staff from infection.

MATERIALS AND METHODS

We conducted feasibility tests to assess the effects of CPR with an automatic load-distributing band (AutoPulse™) in prone position and discussed different aspects of mechanical chest compression (mCPR) in prone position.

RESULTS

In supine position, AutoPulse™ generated a constant pressure depth of 3cm at a frequency of 84/min. In prone position, AutoPulse™ generated a constant pressure depth of 2.6cm at a frequency of 84/min.

CONCLUSION

We found mCPR to be feasible in manikins in both prone and supine positions.

Architecture and functional dynamics of the pentafunctional AROM complex

The AROM complex is a multifunctional metabolic machine with ten enzymatic domains catalyzing the five central steps of the shikimate pathway in fungi and protists. We determined its crystal structure and catalytic behavior, and elucidated its conformational space using a combination of experimental and computational approaches. We derived this space in an elementary approach, exploiting an abundance of conformational information from its monofunctional homologs in the Protein Data Bank. It demonstrates how AROM is optimized for spatial compactness while allowing for unrestricted conformational transitions and a decoupled functioning of its individual enzymatic entities. With this architecture, AROM poses a tractable test case for the effects of active site proximity on the efficiency of both natural metabolic systems and biotechnological pathway optimization approaches. We show that a mere colocalization of enzymes is not sufficient to yield a detectable improvement of metabolic throughput.

[Robot-assisted surgery - Progress or expensive toy? : Matched-pair comparative analysis of robot-assisted cholecystectomy vs. laparoscopic cholecystectomy]

AIM AND METHODS

By means of a matched-pair analysis comparing data obtained from laparoscopic cholecystectomy (LC) and robot-assisted laparoscopic cholecystectomy (RAC), the value of both methods as well as the advantages and disadvantages of both approaches were elucidated. The consideration was carried out by evaluation of postoperative surgical results, a cost analysis and a subjective survey of the patients using a questionnaire. Thus, from the 35 consecutive RAC, 35 (parallel) retrospectively matched pairs were established.

RESULTS

Postoperative surgical results did not show any significant differences between LC and RAC. In the individual assessment by each patient, there were also no significant differences; however, there was a tendency towards the assessment of the RAC to be slightly worse. A striking difference was found with respect to the cost analysis at the time of surgery.

CONCLUSION

The RAC operation alone is significantly more expensive compared to LC with respect to maintenance and acquisition costs. In addition, RAC can at present not be completely reimbursed under the current German diagnosis-related system. The postulated advantages of RAC comprise mainly the precise preparation within narrow confinements and the favorable ergonomic handling for the surgeon. The basic prerequisites are control of the costs and a reasonable reflection in the current reimbursement system.

Chemical Ligand Space of Cereblon

The protein cereblon serves as a substrate receptor of a ubiquitin ligase complex that can be tuned toward different target proteins by cereblon-binding agents. This approach to targeted protein degradation is exploited in different clinical settings and has sparked the development of a growing number of thalidomide derivatives. Here, we probe the chemical space of cereblon binding beyond such derivatives and work out a simple set of chemical requirements, delineating the metaclass of cereblon effectors. We report co-crystal structures for a diverse set of compounds, including commonly used pharmaceuticals, but also find that already minimalistic cereblon-binding moieties might exert teratogenic effects in zebrafish. Our results may guide the design of a post-thalidomide generation of therapeutic cereblon effectors and provide a framework for the circumvention of unintended cereblon binding by negative design for future pharmaceuticals.

[Vascular surgical aspects in abdominal surgery : Results from a tertiary care center over a 10-year time period]

AIM

To investigate the perioperative management and outcome of patients undergoing abdominal surgery with additional vascular (comorbid) alterations for internal quality assurance of the clinical results.

METHODS

Over a defined study period all consecutive cases of the aforementioned profile were documented and retrospectively analyzed as part of an ongoing prospective monocentric observational study to reflect the daily surgical practice.

RESULTS

Over 10 years (from January 1999 to December 2008), a total of 113 cases were registered. Pancreas resection including vascular reconstruction showed the highest percentage (30.1%). Within the target patient groups, similar outcome data were found compared with international reports. An exception was in the case of mesenteric ischemia, where open surgery was more frequently used in comparison to the study situation (included together were patients treated by surgery and interventions). The majority of vascular alterations during the postoperative course and iatrogenic lesions occurred following pancreas resection. In the therapeutic profile there are two particularly important measures, namely open surgery on one hand and image-guided radiology as well as endoscopy on the other hand. The majority of patients with a rare visceral artery aneurysm (considerable potential for rupture or erosion) were more frequently treated with image-guided interventional radiology versus open surgery. This conforms to the current well-established sequential patient (individual), results, and, in particular, risk-adapted staged treatment approach.

CONCLUSION

Additional vascular surgical treatment of problematic situations during abdominal surgery or in emergency cases is not daily routine; however, it is a challenging field including a considerable potential for complications (morbidity) and definitely mortality. This requires an experienced surgeon with high expertise, if possible in a center for vascular medicine.

Target highlights from the first post-PSI CASP experiment (CASP12, May-August 2016)

The functional and biological significance of the selected CASP12 targets are described by the authors of the structures. The crystallographers discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP12 experiment.

[Colovesical fistulas : An interdisciplinary challenge]

BACKGROUND

The aim of treatment of patients with colovesical fistulas should be prompt elimination of the infection and the social burden. We focused on the question whether a minimally invasive surgical approach as a cooperation between surgeons and urologists is possible. This requires effective diagnostics prior to the operation.

METHODS

Since 2007 a total of 32 patients with the clinical suspicion of colovesical fistula have undergone extensive preoperative diagnostics. Operative treatment aimed primarily for a minimally invasive approach. In particular, the validity of preoperative diagnostics was analyzed and surgical results were characterized by clinical success, complications and long-term effects.

RESULTS

The medical history significant for colovesical fistula and detected urinary infection provided the best evidence for the specific diagnosis. Cystoscopy, computed tomography (CT) scan and colonoscopy were only partially effective for predicting a fistula as subsequently diagnosed by histopathological investigations. Fistulas due to diverticulitis of the sigmoid colon occurred in 28 cases, while in 3 subjects there was a gynecological and inflammatory cause (malignant tumor growth, n = 1). A laparoscopic approach achieving repair and healing of the fistula was possible in 29 cases including conversion in 3 subjects because of intraoperative complications. The remaining patients underwent conventional treatment. The disease-related complication rate as revealed during follow-up was 10%.

DISCUSSION

Laparoscopic repair and healing of a colovesical fistula is possible in the majority of cases by the recommended preoperative ureteral stenting. As part of diagnostic measures, the medical history significant for a fistula and detection of urinary infections are the most reliable aspects. In the case of this combination together with a further diagnostic measure, a laparoscopic approach is always recommended. The recurrency rate is 0%.

Origin of a folded repeat protein from an intrinsically disordered ancestor

Repetitive proteins are thought to have arisen through the amplification of subdomain-sized peptides. Many of these originated in a non-repetitive context as cofactors of RNA-based replication and catalysis, and required the RNA to assume their active conformation. In search of the origins of one of the most widespread repeat protein families, the tetratricopeptide repeat (TPR), we identified several potential homologs of its repeated helical hairpin in non-repetitive proteins, including the putatively ancient ribosomal protein S20 (RPS20), which only becomes structured in the context of the ribosome. We evaluated the ability of the RPS20 hairpin to form a TPR fold by amplification and obtained structures identical to natural TPRs for variants with 2-5 point mutations per repeat. The mutations were neutral in the parent organism, suggesting that they could have been sampled in the course of evolution. TPRs could thus have plausibly arisen by amplification from an ancestral helical hairpin.

[Sealing of the hepatic resection area using hemostat devices does not improve results of adequate surgery]

PURPOSE

In hepatic resections, there has been a high quality demand. The aim of this systematic clinical, prospective, unblinded unicenter observational study with two arms in an unselected patient cohort was to investigate whether hemostat device can significantly improve outcome in resective liver surgery, in particular, in high risk patients.

METHODS

All consecutive patients (mean age, 60.5 [range, 17 - 96] years) who underwent hepatic resection (ntotal = 770) were prospectively documented in a computer-based registry at a university hospital (tertiary center) over a time period of 10 years and retrospectively evaluated specifically with regard to the use (-/+; in daily practice and intraoperative decision-making) of hemostat device (Tissucol(®), n = 59/Tachocomb(®), n = 202/combination, n = 55) indicated (among others) by drainage volume, inflammatory parameters and rate of specific complications (nvalidated = 541 [100 %]).

RESULTS

Most frequently, (a-)/typical segmental resections were used: n = 192/90 (3-segment resection, only n = 38). 1) For the assignment of patients to the two different groups (-/+ hemostat device), weight loss and type of resection were found as significant factors (trend: ASA, cirrhosis), for the amount of drainage volume, ASA, sex, Karnofsky Performance Scale and also type of resections using independent distributed statistical tests (such as χ(2), U test [Mann/Whitney]; H test [Kruskal-Willis]; correlation coefficient by Spearman) - no impact: smoking, diabetes, BMI, ethanol. 2) Not taking into account these parameters, the use of hemostat device was characterized by an increased drainage volume (negative control < Tissucol = Tachocomb < combination). 3) Using multifactorial analysis of variance, it was found even under correction by the factors with significant impact elucidated in the single test that the application of hemostat device onto the hepatic resection area resulted unexpectedly rather in an increase than a decrease of the drainage volume but 4) under accompanying more pronounced increase of the white blood cell count (leucocytosis). 5) General and specific complications such as postoperative bleeding, biliary fistula and subhepatic abscess were not further lowered in a significant manner using hemostat device.

CONCLUSION

Adequate surgery in the operative management of hepatic resection area cannot further be improved or optimized using hemostat device. In this context, drainage volume may not be considered a sufficient rather an orienting parameter. However, there is an inflammatory response detectable most likely indicated by a(n un-)specific effusion and increase of white blood cell count, which can be interpreted as a) being characteristic for the problematic group of patients, in whom hemostat device was decided to be useful and was finally used in daily prectice, or b) reactive inflammation to foreign material.

[Colonic stenting: an opportunity with a risk : A critical evaluation]

BACKGROUND

Frequently, the first clinical sign of colorectal cancer is complete obstruction, which has to be considered an emergency situation. The treatment goal is to overcome ileus including reduction of the associated high morbidity and mortality. Therefore, alternative therapeutic options to emergency surgery have been sought in order to allow adequate preparation for elective surgery or stabilization of palliative patients and avoid colostoma. Therapeutic results of the placement of self-expanding metal stents (SEMS) are discussed in terms of a single-center, retrospective observational study.

METHODS

In 35 patients with a clinically manifest stenosis of colonic cancer, it was attempted to insert SEMS to treat ileus as the first therapeutic step. Therapeutic results were investigated with regard to technical and clinical success, spectrum and rate of complications, and survival time, differentiating between a palliative and curative group of patients.

RESULTS

Primary placement of a stent was achieved in 29 of 35 patients (82.9 %); 14 underwent the procedure with palliative and 15 with curative intention. Stent location was mainly the left hemicolon. In 2 of 15 patients (13.3 %), emergency surgery within 48 h was required because of complications, whereby in 13 patients (86.7 %), 6 patients (46.2 %) underwent elective open surgery and 7 patients (53.8 %) underwent a laparoscopic procedure. In all patients treated with curative intent, primary anastomosis was achieved, thus, avoiding a colostoma. Survival times of the palliative and curative patient groups were on average 7 and 28 months, respectively.

CONCLUSION

In carefully selected cases, placement of SEMS in malignant stenosis of the left hemicolon with ileus can be considered a reasonable therapeutic alternative to emergency surgery since it allows surgical intervention with curative intention under more favorable conditions and also avoids a colostoma.

STAC--A New Domain Associated with Transmembrane Solute Transport and Two-Component Signal Transduction Systems

Transmembrane receptors are integral components of sensory pathways in prokaryotes. These receptors share a common dimeric architecture, consisting in its basic form of an N-terminal extracellular sensor, transmembrane helices, and an intracellular effector. As an exception, we have identified an archaeal receptor family--exemplified by Af1503 from Archaeoglobus fulgidus--that is C-terminally shortened, lacking a recognizable effector module. Instead, a HAMP domain forms the sole extension for signal transduction in the cytosol. Here, we examine the gene environment of Af1503-like receptors and find a frequent association with transmembrane transport proteins. Furthermore, we identify and define a closely associated new protein domain family, which we characterize structurally using Af1502 from A. fulgidus. Members of this family are found both as stand-alone proteins and as domains within extant receptors. In general, the latter appear as connectors between the solute carrier 5 (SLC5)-like transmembrane domains and two-component signal transduction (TCST) domains. This is seen, for example, in the histidine kinase CbrA, which is a global regulator of metabolism, virulence, and antibiotic resistance in Pseudomonads. We propose that this newly identified domain family mediates signal transduction in systems regulating transport processes and name it STAC, for SLC and TCST-Associated Component.

Structure of BamA, an essential factor in outer membrane protein biogenesis

Outer membrane protein (OMP) biogenesis is an essential process for maintaining the bacterial cell envelope and involves the β-barrel assembly machinery (BAM) for OMP recognition, folding and assembly. In Escherichia coli this function is orchestrated by five proteins: the integral outer membrane protein BamA of the Omp85 superfamily and four associated lipoproteins. To unravel the mechanism underlying OMP folding and insertion, the structure of the E. coli BamA β-barrel and P5 domain was determined at 3 Å resolution. These data add information beyond that provided in the recently published crystal structures of BamA from Haemophilus ducreyi and Neisseria gonorrhoeae and are a valuable basis for the interpretation of pertinent functional studies. In an `open' conformation, E. coli BamA displays a significant degree of flexibility between P5 and the barrel domain, which is indicative of a multi-state function in substrate transfer. E. coli BamA is characterized by a discontinuous β-barrel with impaired β1-β16 strand interactions denoted by only two connecting hydrogen bonds and a disordered C-terminus. The 16-stranded barrel surrounds a large cavity which implies a function in OMP substrate binding and partial folding. These findings strongly support a mechanism of OMP biogenesis in which substrates are partially folded inside the barrel cavity and are subsequently released laterally into the lipid bilayer.

[Prospective Evaluation of Risk Factors Concerning Intraoperative Conversion from Laparoscopic to Open Cholecystectomy]

BACKGROUND

The surgical approach of choice in the treatment of symptomatic cholecystolithiasis is considered to be elective laparoscopic cholecystectomy (CCE) as the established gold standard. Today, approximately 80-90% of CCE are performed using a laparoscopic approach whereas the remaining portion undergoes primary conventional CCE, however, in 6% conversion is necessary.

AIM

Since pathological aspects found intraoperatively and finally requiring conversion are correlated to an increased risk for complications, it appears reasonable to assess the risk factors prior to operation.

PATIENTS AND METHODS

Through a well defined study period of 9 years, all consecutive patients who underwent CCE for cholecystolithiasis at the Municipal Hospital "HELIOS Klinikum Aue" were enrolled in a registry comparing laparoscopic and conversion CCE. Diverse parameters were tested as to whether they increase significantly the risk for conversion. The intensity of each factor-associated impact on a possible conversion was determined.

RESULTS

From 2001 to 2009 1477 patients underwent CCE at the Municipal Hospital "Helios Klinikum Aue", out of them 131 (8.9%) cases were primarily treated by conventional CCE whereas in the vast majority (1346 subjects [91.1%]), laparoscopic CCE was the initial approach. However, conversion became necessary in 106 individuals resulting in a conversion rate of 7.9%. Comparing data obtained from laparoscopic CCE with those from open procedure after conversion, there were significant differences in operating time, complication rate and postoperative hospital stay (p = 0.01). Over the study period, there were 5 cases (0.37%) with iatrogenic injuries of the biliary system. Hospital mortality was 0.08% in the laparoscopic and 2.8% in the conversion group. The following parameters were found to have a significant impact on the risk for conversion (univariate analysis): elevation of CRP, preoperative ERCP, renal insufficiency, previous laparotomy, histological grade M3 (ulcerous, haemorrhagic necrotising cholecystitis, perforation of the gall bladder) and M4 (carcinoma of the gall bladder). While in the spectrum of preoperative factors former ERCP, elevation of CRP and terminal renal insufficiency were most relevant (2- to 3-fold each), histological grade M3 and M4, 7- and 14-fold, respectively, showed the greatest impact on conversion rate highlighting the profile of postoperative parameters.

CONCLUSION

The main focus is directed to keep the conversion rate low. In case of diagnosing a severely inflamed gall bladder, a primarily open procedure or an early decision for conversion should be considered.

Summary of FDA workshop on ischemia reperfusion injury in kidney transplantation

The Food and Drug Administration (FDA) held an open public workshop in September 2011 to discuss the current state of science related to the effects of ischemia reperfusion injury (IRI) on outcomes in kidney transplantation. Topics included the development of IRI and delayed graft function (DGF), histology and biomarkers, donor factors, recipient factors, organ quality and organ preservation by means of cold storage solutions or machine perfusion. Various mechanisms of injury and maladaptive response to IRI were discussed as potential targets of intervention. Animal models evaluating specific pathophysiological pathways were presented, as were the limitations of extrapolating animal results to humans. Clinical trials of various drug products administered in the peri-transplant period were summarized; a few demonstrated early improvements in DGF, but none demonstrated an improvement in late graft function. Clinical trial design for IRI and DGF were also discussed.

[Hybrid NOS appendectomy (NA): clinical assessment of a new surgical technique]

INTRODUCTION, AIM AND METHOD: Consecutive female patients undergoing hybrid NOS appendectomy (NA - with prospectively collected data) and laparoscopic appendectomy (LA - with retrospectively registered data) were compared by means of a matched-pair analysis according to selected criteria such as patient age, BMI, ASA and previous operations showing a near-perfect congruence with the following aims to: 1) demonstrate the feasibility of NA and to estimate its general costs, and 2) elucidate the outcome of the two techniques using available perioperative parameters from daily clinical practice. In particular, operating time, complications, histopathological findings, postoperative hospital stay and analgesic scores were used for comparison. A gynaecological follow-up investigation was carried out on the day of discharge and after a medium-term time period of 4 weeks in the NA group, and 6 months postoperatively, patients of both groups were interviewed using a standardised questionnaire.

RESULTS

From 05/01/2008 to 02/28/2010, transvaginal NA (n = 30) was compared with the results of the conventional LA (n = 30) in 60 female patients with regard to the operative outcome. Overall, matched-pair analysis of LA with NA, the novel technique resulted in the assessment of basically comparable surgical procedures with regard to perioperative routine parameters and outcome. There were no intraoperative complications in either of the two approaches; conversion was not required in both techniques. In addition, there were no significant differences in operating time (p = 0.099), postoperative complications (p = 0.72) and analgesic scores (p = 0.33/0.46). Postoperative hospital stay was even slightly shorter in the NA group (p = 0.02). The costs of the two methods are almost identical if the same instruments are used. Patient interviews suggested a slightly faster recovery, greater satisfaction with the better cosmetic outcome as well as a reduced pain intensity in favour of transvaginal NA.

CONCLUSION

Provided that a well developed laparoscopic expertise exists, it turned out i) that there are no serious reasons to resist a quick inauguration and establishment of NA for selected cases as well as ii) even to facilitate further clinical distribution of NA. Further systematic data collection appears to be indicated to analyse long-term outcome as parameters of an appropriate quality assurance.

[Matched-pair analysis comparing laparoscopic (LA) vs. single-port appendectomy (SP) for initial assessment of a new surgical approach during its inauguration]

INTRODUCTION

By minimising the invasiveness of a surgical intervention, a reduction of operative trauma can be achieved.

AIM AND METHODS

The aim of this study was based on a theoretical approach to investigate (i) the feasibility of the SP approach and its overall costs, and, furthermore, (ii) the patients' outcome based on simple perioperative parameters available in daily clinical practice. Therefore, single-port (SP) and laparoscopic appendectomies (LA) were compared using a matched-pair analysis. As a prediction, an absolute match between the criteria histology, sex and ASA stage was required.

RESULTS

From 01/01/2009 to 12/31/2010, 196 (60 % were females) consecutive patients underwent appendectomy. Out of them, in 23 patients with either SP or LA appendectomy the predictions for matched-pair analysis (congruence in histopathological finding, sex and ASA criteria) were fulfilled. The operating time was the target criterion for the feasibility of the new surgical method (SP), which could be shortened as seen by comparing SP No. 1-10 with 11-23 (54.6 ± 19.8 min vs. 28.5 ± 18.9 min) expressing the typical effect of a learning curve. The times were similar to those for LA. The postoperative hospital stay and complication rate used to appropriately assess patient outcome did not show a significant difference if comparing SP and LA. Based on the use of single ports, which can be re-used (which has been also a further target) in SP (34.8 %) at the end of the investigation period, SP and LA can be considered comparable surgical techniques with regard to operating times, middle-term outcome and general costs.

CONCLUSION

SP is (in case of well-developed laparoscopic expertise) a surgical method that can be easily inaugurated and considered as a feasible approach in daily surgical practice; it is comparable to LA with regard to outcome and general costs. Based on this, SP can be gradually added to the spectrum of surgical procedures in clinical practice and can be performed in suitable cases. A further systematic institutional or even country-wide case register appears to be recommendable to recruit a larger case number and, thus, to achieve a better knowledge on the perioperative management as well as the especially interesting long-term outcome for an appropriate assessment of treatment quality.

Structural and mechanistic studies of pesticin, a bacterial homolog of phage lysozymes

Yersinia pestis produces and secretes a toxin named pesticin that kills related bacteria of the same niche. Uptake of the bacteriocin is required for activity in the periplasm leading to hydrolysis of peptidoglycan. To understand the uptake mechanism and to investigate the function of pesticin, we combined crystal structures of the wild type enzyme, active site mutants, and a chimera protein with in vivo and in vitro activity assays. Wild type pesticin comprises an elongated N-terminal translocation domain, the intermediate receptor binding domain, and a C-terminal activity domain with structural analogy to lysozyme homologs. The full-length protein is toxic to bacteria when taken up to the target site via the outer or the inner membrane. Uptake studies of deletion mutants in the translocation domain demonstrate their critical size for import. To further test the plasticity of pesticin during uptake into bacterial cells, the activity domain was replaced by T4 lysozyme. Surprisingly, this replacement resulted in an active chimera protein that is not inhibited by the immunity protein Pim. Activity of pesticin and the chimera protein was blocked through introduction of disulfide bonds, which suggests unfolding as the prerequisite to gain access to the periplasm. Pesticin, a muramidase, was characterized by active site mutations demonstrating a similar but not identical residue pattern in comparison with T4 lysozyme.

Summary of the US FDA approval of belatacept

Elements of the Food and Drug Administration (FDA) review of the clinical data that supported the approval of the Biologics License Application (BLA) for belatacept for prophylaxis of organ rejection in adult patients receiving a kidney transplant are summarized. The article is not intended as a comprehensive summary of the entire belatacept data submission. Rather, the discussion is meant to illustrate aspects of the FDA's process for evaluating efficacy and safety, using belatacept as an example.

Structure and mechanism of iron translocation by a Dps protein from Microbacterium arborescens

Dps (DNA protection during starvation) enzymes are a major class of dodecameric proteins that bacteria use to detoxify their cytosol through the uptake of reactive iron species. In the stationary growth phase of bacteria, Dps enzymes are primarily used to protect DNA by biocrystallization. To characterize the wild type Dps protein from Microbacterium arborescens that displays additional catalytic functions (amide hydrolysis and synthesis), we determined the crystal structure to a resolution of 2.05 Å at low iron content. The structure shows a single iron at the ferroxidase center coordinated by an oxo atom, one water molecule, and three ligating residues. An iron-enriched protein structure was obtained at 2 Å and shows the stepwise uptake of two hexahydrated iron atoms moving along channels at the 3-fold axis before a restriction site inside the channels requires removal of the hydration sphere. Supporting biochemical data provide insight into the regulation of this acylamino acid hydrolase. Moreover, the peroxidase activity of the protein was determined. The influence of iron and siderophores on the expression of acylamino acid hydrolase was monitored during several stages of cell growth. Altogether our data provide an interesting view of an unusual Dps-like enzyme evolutionarily located apart from the large Dps sequence clusters.

Structural basis of outer membrane protein biogenesis in bacteria

In Escherichia coli, a multicomponent BAM (β-barrel assembly machinery) complex is responsible for recognition and assembly of outer membrane β-barrel proteins. The functionality of BAM in protein biogenesis is mainly orchestrated through the presence of two essential components, BamA and BamD. Here, we present crystal structures of four lipoproteins (BamB-E). Monomeric BamB and BamD proteins display scaffold architectures typically implied in transient protein interactions. BamB is a β-propeller protein comprising eight WD40 repeats. BamD shows an elongated fold on the basis of five tetratricopeptide repeats, three of which form the scaffold for protein recognition. The rod-shaped BamC protein has evolved through the gene duplication of two conserved domains known to mediate protein interactions in structurally related complexes. By contrast, the dimeric BamE is formed through a domain swap and indicates fold similarity to the β-lactamase inhibitor protein family, possibly integrating cell wall stability in BAM function. Structural and biochemical data show evidence for the specific recognition of amphipathic sequences through the tetratricopeptide repeat architecture of BamD. Collectively, our data advance the understanding of the BAM complex and highlight the functional importance of BamD in amphipathic outer membrane β-barrel protein motif recognition and protein delivery.

Laparoscopic sigmoid resection for diverticular disease has no advantages over open approach: midterm results of a randomized controlled trial

PURPOSE

Elective laparoscopic sigmoid resection (LSR) for symptomatic diverticular disease is supposed to have significant short-term advantages compared to open surgery (open sigmoid resection (OSR)). This opinion is rather based on inferences from trials on colonic resections for malignant diseases or minor laparoscopic surgery. This randomized controlled trial was conducted to compare quality of life as well as morbidity and clinical outcome after LSR vs. OSR following a midterm follow-up period.

METHODS

Patients presenting with a symptomatic sigmoid diverticular disease stage II/III (Stock/Hansen) were randomly allocated to LSR or OSR in a prospective multicenter trial. Endpoints included the quality of life assessed with a standardized questionnaire, postoperative mortality, and complications within the follow-up of 12 months after operation.

RESULTS

A total of 143 patients randomized between 2005 and 2008 in 12 centers could be analyzed. The recruitment was aborted for nonachievement of the planned sample size. Seventy-five patients were allocated to LSR, and 68 received OSR. Nine operations were converted to OSR (9%) and analyzed as intention to treat. Groups were comparable for age, gender, body mass index, comorbidity, and indication for surgery. Operation time was longer for LSR (p < 0.001). Quality of life did not differ between LSR and OSR, either during the early postoperative course or after 12 months (p = 0.172). Also, mortality and morbidity, including subgroups of major and minor morbidity, were compared.

CONCLUSION

LSR was not superior to OSR regarding postoperative quality of life and incidence of complications in this trial.

Summary of FDA antibody-mediated rejection workshop

The Food and Drug Administration (FDA) held an open public workshop in June 2010 to discuss the current state of science related to antibody-mediated rejection (AMR) in kidney transplantation. Desensitization, acute AMR and chronic AMR (CAMR) were considered in the context of clinical trial design. Participants discussed experiences with HLA antibody detection and quantitation and the utility of monitoring donor-specific antibodies (DSAs) to inform the management of patients with AMR. The role for animal models was discussed. Diagnostic and prognostic features of histology were presented, followed by discussion of sensitivity and specificity of various criteria. The published literature on treatment of acute AMR was summarized, which consisted of case series and limited data from controlled clinical trials. Considerations for future clinical trials were presented, including endpoints and statistical evaluations of outcome. Although many issues need further consideration, the meeting enabled an important exchange of ideas between experts in the field.

Expression, purification and crystallization of the Cmi immunity protein from Escherichia coli

Many bacteria kill related bacteria by secretion of bacteriocins. In Escherichia coli, the colicin M protein kills E. coli after uptake into the periplasm. Self-protection from destruction is provided by the co-expressed immunity protein. The colicin M immunity protein (Cmi) was cloned, overexpressed and purified to homogeneity. The correct fold of purified Cmi was analyzed by activity tests and circular-dichroism spectroscopy. Crystallization trials yielded crystals, one of which diffracted to a resolution of 1.9 Å in the orthorhombic space group C222(1). The crystal packing, with unit-cell parameters a = 66.02, b = 83.47, c = 38.30 Å, indicated the presence of one monomer in the asymmetric unit with a solvent content of 53%.

[Is it possible to perform a laparoscopic assisted Hartmann's procedure and a subsequent laparoscopically assisted reversal in complicated diverticulitis?]

Surgery of complicated sigmoid diverticulitis should be as gentle as possible. Serious time pressure, unpredictable operation fields and unprepared bowel determine the surgical strategy. Hence, we examine whether minimal invasive surgery (MIS) (i. e., Hartmann procedure) is suited for emergency conditions in selected patients. Furthermore, the objective of the study was to -assess the feasibility of the reversal of Hartmann procedure in appropriate patients after a preceding classical or laparoscopic intervention. -Between 2005 and 2009 128 patients with sigma diverticulitis were operated, 72 patients of them with complicated sigmoid diverticulitis (peritonitis, haemorrhage, ileus, perforation), The classical Hartmann procedure was performed in 45 (35 %) patients, 39 of them being treated within 24 hours. The laparoscopically assisted Hartmann procedure was realised in 15 patients and could be successfully completed in 13 cases. The cor-responding mortality rate was 0 %. A Hartmann reversal could be performed in 26 patients (58 %). A laparoscopic approach was chosen in 16 patients and could be successfully completed in 14 cases. 12 patients were operated with classical Hartmann reversal. The respective mortality rates in both groups were 0 %. We therefore conclude that in cases of peritonitis due to sigmoid diverticulitis laparoscopic surgery, like laparoscopically assisted Hartmann procedure and a subsequent laparoscopically assisted reversal could be recommended in selected patients.

Crystallization and preliminary X-ray data collection of the Escherichia coli lipoproteins BamC, BamD and BamE

In Escherichia coli, the β-barrel assembly machinery (or BAM complex) mediates the recognition, insertion and assembly of outer membrane proteins. The complex consists of the integral membrane protein BamA (an Omp85-family member) and the lipoproteins BamB, BamC, BamD and BamE. The purification and crystallization of BamC, BamD and BamE, each lacking the N-terminal membrane anchor, is described. While the smallest protein BamE yielded crystals under conventional conditions, BamD only crystallized after stabilization with urea. Full-length BamC did not crystallize, but was cleaved by subtilisin into two domains which were subsequently crystallized independently. High-resolution data were acquired from all proteins.

Decreased use of cervical spine clearance in blunt trauma: the implication of the injury mechanism and distracting injury

BACKGROUND

Cervical spine injury (CSI) can be ruled out based on clinical examination and no X-ray is required if patient is awake, alert, and examinable. This is known as a clinical clearance (CC). Clinicians have decreased the use and reliance of CC and relied more upon X-ray, especially now that computerized tomography (CT) is fast and readily available. The objective of this study was to identify clinical factors, in particular, the injury mechanism and the distracting injuries, which may be associated with CSI. The knowledge may help to improve the use of CC.

METHODS

We retrospectively reviewed the records of all blunt trauma patients who were awake, alert, and examinable, with a Glasgow Coma Scale of 14-15, and who were admitted to our Level 1 Trauma Center during January 1 to December 31, 2005. We excluded patients who presented with gross neurological deficit or who died within 72 h. From the chart review, we collected the demographics; the injury severity score (ISS); the injury mechanism; the presence of distracting injuries (DI) which were defined as bony fractures (divided into upper body, lower body, or both); and the radiographs obtained. Patients who did not receive CC underwent a 3-view plain film X-ray, with or without CT scan. We then divided the group into those with CSI (Case) and those without (Control). We compared the two group variables and performed a multiple logistic regression analysis to identify clinical factors associated with CSI. Statistical significance was accepted with p-value <0.05.

RESULTS

Of the 985 patients evaluated, only 179 (18%) received CC. The remaining did not receive CC and went on to have radiographs. Of these, 76 were diagnosed CSI (Case). On a univariate analysis, the ISS, a motor vehicle collision (MVC) with rollover; MVC with rollover and ejection, the absence of DI, and a lower-body DI were significantly associated with CSI. However, on a multivariate analysis, only an MVC with rollover (odds ratio [OR], 2.326; 95% confidence interval [CI], 1.36-3.97) and a lower-body distracting injury (OR, 0.20; 95% CI, 0.07-0.55) were significantly associated with CSI.

CONCLUSION

The injury mechanism of MVC with rollover may prevent clinicians from utilizing CC, while the presence of a lower-body DI should not. A future and prospective study is needed to better understand the role of the injury mechanism and the distracting injury in relation to CSI.

Changes in quality of life following cognitive-behavioral group therapy for panic disorder

BACKGROUND

Data about quality of life (QoL) are important to estimate the impact of diseases on functioning and well-being. The present study was designed to assess the association of different aspects of panic disorder (PD) with QoL and to examine the relationship between QoL and symptomatic outcome following brief cognitive-behavioral group therapy (CBGT).

METHOD

The sample consisted of 55 consecutively recruited outpatients suffering from PD who underwent CBGT. QoL was assessed by the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) at baseline, post-treatment and six months follow-up. SF-36 baseline scores were compared with normative data obtained from a large German population sample.

RESULTS

Agoraphobia, disability, and worries about health were significantly associated with decreased QoL, whereas frequency, severity and duration of panic attacks were not. Treatment responders showed significantly better QoL than non-responders. PD symptom reduction following CBGT was associated with considerable improvement in emotional and physical aspects of QoL. However, the vitality subscale of the SF-36 remained largely unchanged over time.

CONCLUSIONS

Our results are encouraging for cognitive-behavior therapists who treat patients suffering from PD in groups, since decrease of PD symptoms appears to be associated with considerable improvements in QoL. Nevertheless, additional interventions designed to target specific aspects of QoL, in particular vitality, may be useful to enhance patients' well-being.

Structural basis of N-end rule substrate recognition in Escherichia coli by the ClpAP adaptor protein ClpS

In Escherichia coli, the ClpAP protease, together with the adaptor protein ClpS, is responsible for the degradation of proteins bearing an amino-terminal destabilizing amino acid (N-degron). Here, we determined the three-dimensional structures of ClpS in complex with three peptides, each having a different destabilizing residue--Leu, Phe or Trp--at its N terminus. All peptides, regardless of the identity of their N-terminal residue, are bound in a surface pocket on ClpS in a stereo-specific manner. Several highly conserved residues in this binding pocket interact directly with the backbone of the N-degron peptide and hence are crucial for the binding of all N-degrons. By contrast, two hydrophobic residues define the volume of the binding pocket and influence the specificity of ClpS. Taken together, our data suggest that ClpS has been optimized for the binding and delivery of N-degrons containing an N-terminal Phe or Leu.