Short-stem reconstruction for megaendoprostheses in case of an ultrashort proximal femur

Background

Tumors of the distal femur and diaphysis with proximal metaphyseal extension into the femur present a challenge for limb salvage. The conventional treatment consists of limb salvage with total femur replacement. This case study aims to present preliminary results and experience with short-stem reconstruction, focusing on the mechanical stability of the procedure.

Methods

Sixteen short stems were implanted in 15 patients. The patients’ mean age was 33,3 years (range 11–73). In 10 patients, the stem was used for distal femur reconstruction, in one patient for diaphyseal reconstruction, and in four for a stump lengthening procedure. All of the patients had a primary sarcoma in their history. The mean follow-up period was 37 months (range 5–95 months). The clinical and functional follow-up data were analyzed.

Results

Ten patients (67%) were still alive at the time of evaluation. Three complications associated with the stem were noted. In one case, there was aseptic loosening after 58 months; in another, aseptic loosening occurred because the diameter of the stem had initially been too small; and in one case, there was breakage of the fixation screw, without any clinical symptoms. The average Musculoskeletal Tumor Society score for all patients was 23 (range 9–28). The mean result for the distal femur replacement was 24 (range 22–28). None of the surviving patients with distal femur replacements needed any crutches or had a Trendelenburg limp. Both living patients who underwent a stump lengthening procedure were able to walk with an exoprosthesis.

Conclusions

The short stem is a good solution that can prevent or delay proximal femur resection in patients with tumors extending into the proximal metaphyseal femur. Additional risks of proximal femur resection, such as dislocation, opening of another oncological compartment, Trendelenburg limp, and chondrolysis can be avoided.

Endoprosthetic replacement after extra-articular resection of bone and soft-tissue tumours around the knee

We evaluated the clinical results and complications after extra-articular resection of the distal femur and/or proximal tibia and reconstruction with a tumour endoprosthesis (MUTARS) in 59 patients (mean age 33 years (11 to 74)) with malignant bone or soft-tissue tumours. According to a Kaplan-Meier analysis, limb survival was 76% (95% confidence interval (CI) 64.1 to 88.5) after a mean follow-up of 4.7 years (one month to 17 years). Peri-prosthetic infection was the most common indication for subsequent amputation (eight patients). Survival of the prosthesis without revision was 48% (95% CI 34.8 to 62.0) at two years and 25% (95% CI 11.1 to 39.9) at five years post-operatively. Failure of the prosthesis was due to deep infection in 22 patients (37%), aseptic loosening in ten patients (17%), and peri-prosthetic fracture in six patients (10%). Wear of the bearings made a minor revision necessary in 12 patients (20%). The mean Musculoskeletal Tumor Society score was 23 (10 to 29). An extensor lag > 10° was noted in ten patients (17%). These results suggest that limb salvage after extra-articular resection with a tumour prosthesis can achieve good functional results in most patients, although the rates of complications and subsequent amputation are higher than in patients treated with intra-articular resection.

Femoro-tibial kinematics after TKA in fixed- and mobile-bearing knees in the sagittal plane

PURPOSE

Lack of the anterior cruciate ligament in total knee arthroplasty results in paradoxical movement of the femur as opposed to the tibia under deep flexion. Total knee arthroplasty with mobile-bearing inlays has been developed to provide increased physiological movement of the knee joint and to reduce polyethylene abrasion. The aim of this study was to perform an in vitro analysis of the kinematic movement in the sagittal plane in order to show differences between fixed- and mobile-bearing TKA in comparison with the natural knee joint.

METHODS

Seven knee joints of human cadaver material were used in a laboratory experiment. Fixed- and mobile-bearing inlays were tested in sequences under isokinetic extension in so-called kinemator for knee joints, which can simulate muscular traction power by the use of hydraulic cylinders, which crossover the knee joint. As a target parameter, the a.p. translation of the tibio-femoral relative movement was measured in the sagittal plane under ultrasound (Zebris) control.

RESULTS

The results show a reduced tibial a.p. translation in relation to the femur in the bearing group compared to the natural joint. In the Z-axis, between 110° and 50° of flexion, linear movement decreases towards caudal movement under extension. Admittedly, the study did not show differences in the movement pattern between "mobile-bearing" and "fixed-bearing" prostheses.

CONCLUSION

Results of this study cannot prove functional advantages of mobile-bearing prostheses for the knee joint kinematic after TKA. Both types of prostheses show typical kinematics of an anterior instability, hence they were incapable of performing physiological movement.

Cell-free synthesis of functional thermostable direct hemolysins of Vibrio parahaemolyticus

Vibrio parahaemolyticus is a recognized enteropathogen causing diarrhea in humans and is one of the major causes of seafoodborne gastroenteritis. An important virulence factor is thermostable direct hemolysin (TDH), a pore-forming toxin, which is able to lyse eukaryotic cells. The active toxin is a tetramer of four identical protein subunits, which is secreted by the pathogen after cleavage of a signal peptide. To establish diagnostic detection systems for TDH we expressed the hemolysin with and without the signal peptide in a prokaryotic cell-free system to obtain pure toxin. In order to purify and to facilitate the isolation from cell lysates we synthesized TDH variants with different tags. Important regulatory sequences for cell-free protein synthesis as well as sequences for N-terminal Strep-tag and C-terminal 6xHis-tag were added by a two-step PCR. For the expression in the cell-free system these linear tdh templates were subjected directly to prokaryotic cell extracts. Protein yields were in the range of 500-600 μg/ml for the preproteins and approx. 300-400 μg/ml for the mature proteins. The identities of expressed proteins were further confirmed by SDS-PAGE, immunological and MALDI-TOF mass spectrometric analyses. The functionality of newly synthesized toxin variants was tested by performing qualitative and semiquantitative hemolysis assays. Cell-free produced mature TDH and its variants were active while the preprotein and its derivatives lacked hemolytic activity. A C-terminal 6xHis-tag showed less influence on functionality compared to the N-terminal Strep-tag.

Evaluation of a reconstruction reverse shoulder for tumour surgery and tribological comparision with an anatomical shoulder arthroplasty

PURPOSE

The functional results after reconstruction of the proximal humerus in tumour surgery are poor. Therefore, a reversed proximal humerus replacement was developed in our institution (MUTARS humerus inverse). A low degree of wear on the polyethylene is required because of the patients' youth and demands on shoulder function. A special type of polyethylene with shock-absorbing properties has been developed to minimise polyethylene wear in the MUTARS inverse proximal humerus replacement. We compared the tribological properties of an anatomical shoulder prosthesis (CAPICA) with the new reversed proximal humerus replacement (MUTARS humerus inverse).

METHODS

Both prostheses were tested up to 5 × 10(6) cycles. Every millionth cycle the surface was inspected and a gravimetric measurement was performed. A measurement of surface roughness was done before testing and after 5 × 10(6) cycles.

RESULTS

In both prostheses after 5 × 10(6) cycles there were no major defects, such as delamination, observed. In the reversed proximal humerus replacement abrasion of 28 mg/10(6) cycles was detected. The mean abrasion of the anatomical prosthesis was 9.28 mg/ 10(6) cycles.

CONCLUSION

The glenoid component of the first reversed humerus replacement (MUTARS humerus inverse) has wear properties comparable to those of normal reversed shoulder prostheses. This is important, as this type of prosthesis is used in young patients after resection of bone tumours, with a good functional outcome. It can, therefore, be expected that the revision rate due to wear will be as high as in patients with normal reversed shoulder prostheses.

Distal femur and proximal tibia replacement with megaprosthesis in revision knee arthroplasty: a limb-saving procedure

PURPOSE

The aim of the present study was to assess whether using megaprostheses in revision knee arthroplasty procedures allows limb salvage with an acceptable outcome and complication rate, in comparison with other limb-saving procedures.

METHODS

Between 2000 and 2010, megaprosthesis implantation was required for non-oncologic indications in 20 patients (21 knees) (average age 73 years). Reconstructions involved the distal femur (n = 15), proximal tibia (n = 4), and both femur and tibia (n = 2). The indications, type, and numbers of previous operations and implants, as well as complications associated with megaprosthesis implantation, were reviewed, and the clinical and radiographic outcomes after an average follow-up period of 34 months (range 10-84 months) were evaluated.

RESULTS

The indications for megaprosthesis implantation were periprosthetic infection (n = 5), fracture (n = 9), nonunion (n = 5), and aseptic loosening (n = 2). The types of implant placed before the megaprosthetic reconstruction were a cemented rotating-hinge arthroplasty (n = 16) and a primary total knee arthroplasty (n = 5). Six patients had an additional osteosynthesis of the distal femur. An average of 3.8 operations (range 1-7) had been carried out before megaprosthesis implantation. Complications developed in 11 patients. The Knee Society Score improved significantly, from 43 (± 15) to 68 (± 16.8); P < 0.05.

CONCLUSIONS

Megaprosthesis implantation in revision knee arthroplasty is an exceptional indication. Despite the high complication rate, the patients can be spared amputation in most cases, and rapid mobilization with full weight-bearing is possible.

[Diagnostics and therapy for periprosthetic joint infection in Germany - A survey of 450 hospitals and a comparison with the literature]

The diagnosis and treatment of periprosthetic joint infections is a difficult situation for the attending physician. From the extensive literature, algorithms for diagnosis and therapy can be created. The aim of this study was to collect a representative survey of current concepts in the Federal States of the former West Germany and to compare them with those in the current literature. In 2011 orthopaedic and trauma clinics were surveyed anonymously in western Germany about diagnosis and treatment of periprosthetic infections. 450 questionnaires could be evaluated. Septic hip arthroplasty revisions were performed on average 12 (± 20)/year, septic knee arthroplasty revisions were performed on average 9 (± 17)/year. On average 205 (± 178) primary hip and 167 (± 155) primary knee arthroplasties were implanted/year. The analysis of the collected parameters is summarised in three tables. In the field of diagnostics, parameters such as CRP are determined. The interpretation, however, differs in more than 50 % of the hospitals on the relevant literature. Some important diagnostic parameters are not used. Therapy concepts are largely consistent with the literature. To a non-negligible extent, the vacuum-assisted therapy (approximately 30 % of hospitals) is used. In the literature it is described only for early infection. But even for use in early infection, there are very few data available. A unified diagnostic algorithm would be desirable.

The Burch-Schneider cage for reconstruction after metastatic destruction of the acetabulum: outcome and complications

INTRODUCTION

The Burch-Schneider cage is an established implant in revision surgery after hip arthroplasty that is used for reconstructing osseous defects in the acetabulum. However, there are only a few reports about the use of cages in patients with metastatic destruction of the acetabulum. The aim of this retrospective study was to assess the outcome and complications of this procedure.

METHODS

The records of 15 patients with metastatic acetabular defects using the Burch-Schneider cage were examined pre- and postoperatively. X-rays were analyzed, clinical and functional outcome was assessed by the Harris hip score (HHS) and the visual analogue scale (VAS) for subjective pain perception. The follow-up of 14 months was due to the underlying disease.

RESULTS

The overall revision rate was 26%. The HHS improved from 33 (range 25-39) to 69 (range 35-93). The VAS improved from 7.5 to 3.2.

CONCLUSION

The life expectancy of patients with bone metastasis can be short and patients should be carefully selected for a surgical treatment. The implantation of a protrusio cage can improve the quality of life in these patients by increasing their mobility and reducing pain. The complication rate is comparable with the rates for other surgical methods for metastatic acetabular lesions. For surgeons who are familiar with this implant, it seems to be a good option in treating such cases.

Patellar resurfacing as a second stage procedure for persistent anterior knee pain after primary total knee arthroplasty

PURPOSE

Knee pain after total knee arthroplasty may be caused by an unresurfaced patella. Secondary isolated resurfacing of the previously unresurfaced patella in total knee arthroplasty remains controversial. The aim of this retrospective study was to evaluate the outcome after patellar resurfacing as a second stage procedure.

METHODS

The study included 22 patients (13 female/nine male) who underwent resurfacing of the patella with a mean follow-up of 61.8 ± 39.2 months. The mean age of the patients was 60 ± 9.7 years at the time of operation. The average period between total knee arthroplasty and patellar resurfacing was 26.3 ± 15.2 months. The patient's subjective satisfaction was assessed by a custom-made questionnaire.

RESULTS

The mean Knee Society Score improved significantly from 60.1 ± 8.3 to 77.0 ± 6.3 (p = 0.0063). The mean functional score also improved significantly from 42.7 ± 2.3 to 60.2 ± 3.9 (p = 0.001). Three patients (13.6%) needed further operative revision.

CONCLUSIONS

Although clinical scores showed significant improvement some patients continued to have pain and remained dissatisfied without detecting a specific reason. Further studies are needed to better elucidate the benefit of patellar resurfacing as second stage procedure.

The treatment of locally recurrent chondrosarcoma

The aim of this study was to define the treatment criteria for patients with recurrent chondrosarcoma. We reviewed the data of 77 patients to examine the influence of factors such as the intention of treatment (curative/palliative), extent of surgery, resection margins, status of disease at the time of local recurrence and the grade of the tumour. A total of 70 patients underwent surgery for recurrent chondrosarcoma. In seven patients surgery was not a viable option. Metastatic disease occurred in 41 patients, appearing synchronously with the local recurrence in 56% of cases. For patients without metastasis at the time of local recurrence, the overall survival at a mean follow-up after recurrence of 67 months (0 to 289) was 74% (5 of 27) compared with 19% (13 of 50) for patients with metastasis at or before the development of the recurrence. Neither the type/extent of surgery, site of tumour, nor the resection margins for the recurrent tumour significantly influenced the overall survival.

With limited survival for patients with metastatic disease at the time of local recurrence (0% for patients with grade III and de-differentiated chondrosarcoma), palliative treatment, including local radiation therapy and debulking procedures, should be discussed with the patients to avoid long hospitalisation and functional deficits. For patients without metastasis at the time of local recurrence, the overall survival of 74% justifies an aggressive approach including wide resection margins and extensive reconstruction.

Intramedullary and total femur replacement in revision arthroplasty as a last limb-saving option

There has been a substantial increase in the number of hip and knee prostheses implanted in recent years, with a consequent increase in the number of revisions required. Total femur replacement (TFR) following destruction of the entire femur, usually after several previous revision operations, is a rare procedure but is the only way of avoiding amputation. Intramedullary femur replacement (IFR) with preservation of the femoral diaphysis is a modification of TFR. Between 1999 and 2010, 27 patients with non-oncological conditions underwent surgery in our department with either IFR (n = 15) or TFR (n = 12) and were included in this study retrospectively. The aim of the study was to assess the indications, complications and outcomes of IFR and TFR in revision cases. The mean follow-up period was 31.3 months (6 to 90). Complications developed in 37% of cases, 33% in the IFR group and 4% in the TFR group. Despite a trend towards a slightly better functional outcome compared with TFR, the indication for intramedullary femur replacement should be established on a very strict basis in view of the procedure’s much higher complication rate.

5-(4-Hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7-phenyl-2,3,6,7-tetrahydro-1,4-thiazepines as compounds with high affinity at the benzodiazepine binding site on GABA(A) receptors

A series of thiazepines has been studied as new ligands for the benzodiazepine binding site of the GABAA receptor. Compounds with high affinity and weak selectivity regarding alpha beta3gamma2, alpha2beta3gamma2, alpha3beta3gamma2, and alpha5beta3gamma2 subtypes were found. The pharmacophore is discussed based on experimental and theoretical results. The thiazepine sulfur atom was found to be able to act as hydrogen bond acceptor.

Rapid identification and characterization of Vibrio species using whole-cell MALDI-TOF mass spectrometry

AIMS

Vibrio identification by means of traditional microbiological methods is time consuming because of the many biochemical tests that have to be performed to distinguish closely related species. This work aimed at evaluating the use of MALDI-TOF mass spectrometry for the rapid identification of Vibrio (V.) spp. as an advantageous application to rapidly discriminate the most important Vibrio spp. and distinguish Vibrio spp. from closely related bacterial species like Photobacterium damselae and Grimontia hollisae and other aquatic bacteria like Aeromonas spp.

METHODS AND RESULTS

Starting from sub-colony amounts of pure cultures grown on agar plates, a very simple sample preparation procedure was established and combined with a rapid and automated measurement protocol that allowed species identification within minutes. Closely related species like Vibrio alginolyticus and Vibrio parahaemolyticus or Vibrio cholerae and Vibrio mimicus could thus be differentiated by defining signatures of species-identifying biomarker ions (SIBIs). As a reference method for species designation and for determination of relationships between strains with molecular markers, partial rpoB gene sequencing was applied.

CONCLUSIONS

The MALDI-TOF MS-based method as well as the rpoB sequence-based approach for Vibrio identification described in this study produced comparable classification results. The construction of phylogenetic trees from MALDI-TOF MS and rpoB sequences revealed a very good congruence of both methods.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results suggest that whole-cell MALDI-TOF MS-based proteometric characterization represents a powerful tool for rapid and accurate classification and identification of Vibrio spp. and related species.

Differential regulation and posttranslational processing of the class II hydrophobin genes from the biocontrol fungus Hypocrea atroviridis

Hydrophobins are small extracellular proteins, unique to and ubiquitous in filamentous fungi, which mediate interactions between the fungus and environment. The mycoparasitic fungus Hypocrea atroviridis has recently been shown to possess 10 different class II hydrophobin genes, which is a much higher number than that of any other ascomycete investigated so far. In order to learn the potential advantage of this hydrophobin multiplicity for the fungus, we have investigated their expression patterns under different physiological conditions (e.g., vegetative growth), various conditions inducing sporulation (light, carbon starvation, and mechanical injury-induced stress), and confrontation with potential hosts for mycoparasitism. The results show that the 10 hydrophobins display different patterns of response to these conditions: one hydrophobin (encoded by hfb-2b) is constitutively induced under all conditions, whereas other hydrophobins were formed only under conditions of carbon starvation (encoded by hfb-1c and hfb-6c) or light plus carbon starvation (encoded by hfb-2c, hfb-6a, and hfb-6b). The hydrophobins encoded by hfb-1b and hfb-5a were primarily formed during vegetative growth and under mechanical injury-provoked stress. hfb-22a was not expressed under any conditions and is likely a pseudogene. None of the 10 genes showed a specific expression pattern during mycoparasitic interaction. Most, but not all, of the expression patterns under the three different conditions of sporulation were dependent on one or both of the two blue-light regulator proteins BLR1 and BLR2, as shown by the use of respective loss-of-function mutants. Matrix-assisted laser desorption ionization-time of flight mass spectrometry of mycelial solvent extracts provided sets of molecular ions corresponding to HFB-1b, HFB-2a, HFB-2b, and HFB-5a in their oxidized and processed forms. These in silico-deduced sequences of the hydrophobins indicate cleavages at known signal peptide sites as well as additional N- and C-terminal processing. Mass peaks observed during confrontation with plant-pathogenic fungi indicate further proteolytic attack on the hydrophobins. Our study illustrates both divergent and redundant functions of the 10 hydrophobins of H. atroviridis.

Rapid classification and identification of salmonellae at the species and subspecies levels by whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometry

Variations in the mass spectral profiles of multiple housekeeping proteins of 126 strains representing Salmonella enterica subsp. enterica (subspecies I), S. enterica subsp. salamae (subspecies II), S. enterica subsp. arizonae (subspecies IIIa), S. enterica subsp. diarizonae (subspecies IIIb), S. enterica subsp. houtenae (subspecies IV), and S. enterica subsp. indica (subspecies VI), and Salmonella bongori were analyzed to obtain a phylogenetic classification of salmonellae based on whole-cell matrix-assisted laser desorption ionization-time of flight mass spectrometric bacterial typing. Sinapinic acid produced highly informative spectra containing a large number of biomarkers and covering a wide molecular mass range (2,000 to 40,000 Da). Genus-, species-, and subspecies-identifying biomarker ions were assigned on the basis of available genome sequence data for Salmonella, and more than 200 biomarker peaks, which corresponded mainly to abundant and highly basic ribosomal or nucleic acid binding proteins, were selected. A detailed comparative analysis of the biomarker profiles of Salmonella strains revealed sequence variations corresponding to single or multiple amino acid changes in multiple housekeeping proteins. The resulting mass spectrometry-based bacterial classification was very comparable to the results of DNA sequence-based methods. A rapid protocol that allowed identification of Salmonella subspecies in minutes was established.

Spongiibacter marinus gen. nov., sp. nov., a halophilic marine bacterium isolated from the boreal sponge Haliclona sp. 1

Strain HAL40b(T) was isolated from the marine sponge Haliclona sp. 1 collected at the Sula Ridge off the Norwegian coast and characterized by physiological, biochemical and phylogenetic analyses. The isolate was a small rod with a polar flagellum. It was aerobic, Gram-negative and oxidase- and catalase-positive. Optimal growth was observed at 20-30 degrees C, pH 7-9 and in 3 % NaCl. Substrate utilization tests were positive for arabinose, Tween 40 and Tween 80. Enzyme tests were positive for alkaline phosphatase, esterase lipase (C8), leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase and N-acetyl-beta-glucosaminidase. The predominant cellular fatty acid was C(17 : 1) omega8, followed by C(17 : 0) and C(18 : 1) omega7. Analysis by matrix-assisted laser desorption/ionization time-of-flight MS was used to characterize the strain, producing a characteristic low-molecular-mass protein pattern that could be used as a fingerprint for identification of members of this species. The DNA G+C content was 69.1 mol%. Phylogenetic analysis supported by 16S rRNA gene sequence comparison classified the strain as a member of the class Gammaproteobacteria. Strain HAL40b(T) was only distantly related to other marine bacteria including Neptunomonas naphthovorans and Marinobacter daepoensis (type strain sequence similarity >90 %). Based on its phenotypic, physiological and phylogenetic characteristics, it is proposed that the strain should be placed into a new genus as a representative of a novel species, Spongiibacter marinus gen. nov., sp. nov.; the type strain of Spongiibacter marinus is HAL40b(T) (=DSM 17750(T) =CCUG 54896(T)).

Atrasentan treatment of pulmonary vascular disease in piglets with increased pulmonary blood flow

We studied the effect of chronic endothelin A receptor blockade by atrasentan on the pulmonary endothelin-1 system and vascular endothelial growth factor (VEGF) expression in piglets with high pulmonary blood flow. Twenty-five 4-week-old piglets with high pulmonary blood flow were randomized to three groups: sham operated (n = 8), placebo (water) (n = 7), or treatment with atrasentan (2 mg/kg per day) (n = 10). After 3 months, mean pulmonary arterial pressure (PAP) was higher in the placebo group than in the sham group [18 +/- 2 mm Hg versus 14 +/- 1 mm Hg; P < 0.05 (ANOVA)]. Atrasentan treatment was associated with lower cardiac output, PAP (14 +/- 1 mm Hg), and medial wall thickness of pulmonary arteries (diameter: 50-150 microM) compared with placebo [13.6 +/- 3.0% versus 18.1 +/- 4.2%; P < 0.05 (ANOVA)]. Quantitative real-time polymerase chain reaction for endothelin-1, endothelin B receptor, and endothelin-converting enzyme-1 mRNA in lung tissue did not differ. However, immunostaining as well as mRNA for VEGF were lower in atrasentan-treated animals (relative gene expression: atrasentan versus placebo: 0.8 +/- 0.3 versus 1.5 +/- 0.3; P = 0.009). Atrasentan treatment effectively reduces medial hypertrophy in piglets with chronic pulmonary hyperperfusion. Chronic endothelin A receptor blockade by atrasentan may interfere with the expression of VEGF.

Intact-cell MALDI-TOF mass spectrometry analysis of peptaibol formation by the genus Trichoderma/Hypocrea: can molecular phylogeny of species predict peptaibol structures?

Peptaibols are characteristic linear alpha-aminoisobutyrate-containing peptides produced by certain Ascomycetes, especially of the genus Hypocrea/Trichoderma [Hypocrea and Trichoderma are the names for the teleo- and anamorph forms of the same taxon; where known to occur in nature, the teleomorph is used to name the species. To aid the inexperienced reader, both names (the less well known one in parentheses) are given at the first mention of each species.] Here we have investigated whether phylogenetic relationships within Trichoderma permit a prediction of the peptaibol production profiles. To this end, representative strains from a third (28) of the known species of Trichoderma, identified by the sequences of diagnostic genes and covering most clades of the established multilocus phylogeny of Trichoderma/Hypocrea, were investigated by intact-cell MALDI-TOF mass spectrometry. Peptaibols were detected in all strains, and some strains were found to produce up to five peptide families of different sizes. Comparison of the data with phylogenies derived from rRNA spacer regions (ITS1 and 2) and RNA polymerase subunit B (rpb2) gene sequences did not show a strict correlation with the types and sequences of the peptaibols produced, but the production of some groups of peptaibols appears to be found only in some clades or sections of the genus, which could be used for more targeted screening of novel compounds of this type. In an analysis of peptaibol structures, we have defined conserved key positions and have further identified and compared sequences of the corresponding adenylate domains within non-ribosomal peptide synthetases producing trichovirins, paracelsins and atroviridins. These phylogenies are not concordant with those of their producers Hypocrea virens, Hypocrea jecorina and Hypocrea atroviridis as obtained from ITS1 and 2, and rpb2, respectively, and therefore hint at a complex history of peptaibol diversity.

Peptaibol production by sepedonium strains parasitizing boletales

Fungi of the genus Sepedonium (anamorphic ascomycetes) are known to infect fruiting bodies of Basidiomycetes of the order Boletales. We have characterized twelve Sepedonium isolates by intact-cell mass spectrometry (IC-MS) with the help of respective biomarkers and their metabolite spectra focusing on peptaibol production. A strain of mycoparasitic S. chalcipori was grown in solid-state fermentation, and tylopeptin production was found, suggesting an ascomycete origin of these peptaibols, which were first described in the basidiomycete Tylopilus neofelleus. In addition, the structures of two new peptaibols, chalciporin A (=Ac-Trp-Val-Aib-Val-Ala-Gln-Ala-Aib-Ser-Leu-Ala-Leu-Aib-Gln-Leuol) and chalciporin B (=Ac-Trp-Val-Aib-Val-Ala-Gln-Ala-Aib-Gln-Aib-Ala-Leu-Aib-Gln-Leuol) are presented. The IC-MS technique was applied for in situ peptaibol analysis of Sepedonium strains growing on Boletales, in particular S. chrysospermum infecting Xerocomus cf. badius. We found chrysospermins at the surface and within basidiomycete tissue, as well as in the cultivated parasite.

Direct identification of hydrophobins and their processing in Trichoderma using intact-cell MALDI-TOF MS

Intact-cell MS (ICMS) was applied for the direct detection of hydrophobins in various species and strains of Hypocrea/Trichoderma. In both mycelia and spores, dominating peaks were identified as hydrophobins by detecting mass shifts of 8 Da of reduced and unreduced forms, the analysis of knockout mutants, and comparison with protein databases. Strain-specific processing was observed in the case of Hypocrea jecorina (anamorph Trichoderma reesei). An analysis of 32 strains comprising 29 different species of Trichoderma and Hypocrea showed hydrophobin patterns that were specific at both at the species and isolate (subspecies) levels. The method therefore permits rapid and direct detection of hydrophobin class II compositions and may also provide a means to identify Trichoderma (and other fungal) species and strains from microgram amounts of biomass without prior cultivation.

Full recovery of electron damage in glass at ambient temperatures

An unusually complete recovery of extensive electron-beam-induced damage in a thin film of a CaO-Al2O3-SiO2 glass was discovered. Nanoscale measurements show that the Ca ions migrate about 10 nm away during irradiation and return during recovery. Oxygen atoms are trapped largely as molecular oxygen and do not migrate. Electron energy loss measurements demonstrate that the glass returns completely to the original compositional and structural state thus indicating that the glass is in a deep thermodynamic energy minimum.

Nonribosomal Peptide Synthesis in Schizosaccharomyces pombe and the Architectures of Ferrichrome-Type Siderophore Synthetases in Fungi

A nonribosomal peptide synthetase (NRPS) in Schizosaccharomyces pombe, which possesses an unusual structure incorporating three adenylation domains, six thiolation domains and six condensation domains, has been shown to produce the cyclohexapeptide siderophore ferrichrome. One of the adenylation domains is truncated and contains a distorted key motif. Substrate-binding specificities of the remaining two domains were assigned by molecular modelling to glycine and to N-acetyl-N-hydroxy-L-ornithine. Hexapeptide siderophore synthetase genes of Magnaporthe grisea and Fusarium graminearum were both identified and analyzed with respect to substrate-binding sites, and the predicted product ferricrocin was identified in each. A comparative analysis of these synthetase systems, including those of the basidiomycete Ustilago maydis, the homobasidiomycete Omphalotus olearius and the ascomycetes Aspergillus nidulans, Aspergillus fumigatus, Fusarium graminearum, Cochliobolus heterostrophus, Neurospora crassa and Aureobasidium pullulans, revealed divergent domain compositions with respect to their number and positioning, although all produce similar products by iterative processes. A phylogenetic analysis of both NRPSs and associated L-N5-ornithine monooxygenases revealed that ferrichrome-type siderophore biosynthesis has coevolved in fungi with varying in trans interactions of NRPS domains.

Biomechanical evaluation of a bioabsorbable expansion bolt for hamstring graft fixation in ACL reconstruction: an experimental study in calf tibial bone

INTRODUCTION

The purpose of our study was to evaluate and compare the primary fixation strength of a novel bioabsorbable two shell expansion bolt (EB) with that of a well-established interference screw-fixation technique in hamstring reconstruction of the anterior cruciate ligament.

MATERIALS AND METHODS

Thirty calf tibia plateaus (age 5-6 months) were assigned to three groups: In group I (n = 10) triple-stranded hamstring grafts were fixed with titanium interference screws (7 mm thread / 8 mm head x 25 mm). Specimens of group II (n = 10) received bioabsorbable poly-L-lactide interference screws (8 x 23 mm). In group III (n = 10), the grafts were fixed using bioabsorbable poly-D,L-lactide expansion bolts (5.8/8.5/10 mm x 35 mm). The tensile axis was placed parallel to the bone tunnel. The construction was then loaded until failure under a displacement rate of 1 mm per second.

RESULTS

There were no significant differences concerning the maximum pullout force (group I: 357 N +/- 61; group II: 326 N +/- 92; group III: 343 N +/- 55). In case of the expansion bolt, we found the stiffness to be higher (61 N/mm) when compared to group I (48 N/mm), and group II (52N/mm) (P < 0.01 I vs. III). Using interference screws, we were able to demonstrate a strong correlation between torque and pullout forces (group I: r2 = 0.7; group II: r2 = 0.92). Ruptures of the suturing material occurred only in groups I and II.

CONCLUSION

We conclude that hamstring graft fixation, using the presented expansion bolt, demonstrates fixation strength similar to the established screw fixation and can therefore be regarded as a reasonable alternative fixation method. Especially, since some specific disadvantages of screw fixation can be prevented by application of the bolt fixation.

Relationship between activating and editing functions of the adenylation domain of apo-tyrocidin synthetase 1 (apo-TY1)

Tyrocidine synthetase 1 (TY1), the initial monomodular constituent of the tyrocidine biosynthetic system, exhibits relaxed substrate specificity, however an efficient editing of the mis-activated amino acid provides for fidelity of product formation. We chose to analyse the consequence of single amino acid substitutions, in the amino acid activation site of apo-TY1, on the editing functions of the enzyme. Discrimination between L-Phe and D-Phe by apo-TY1 depends primarily on the editing reaction. Distraction of unnatural amino acid substrates, such as L-PheSer, implies that editing is not designated to select a specific mis-activated amino acid, but instead to discriminate all mis-activated amino acid analogues. It was shown that active site residues which interact with the adenylate are essential for both activation and editing. Substitution of Lys186 with arginine substantially reduces the editing capacity of the protein. Loss of amino acid discrimination ability by the apo-K186T and apo-R416T mutant proteins suggests a role of active site residues in maintaining the structural determinants for substrate selection. Inadequate conformational changes, induced by non-cognate amino acid substrates, promote ATP breakdown yielding P(i) and ADP. Replacement of residue Lys186 or Arg416 enhances ATP hydrolysis implying a role in binding or adjusting of the triphosphate chain for adenylate formation and pyrophosphate cleavage.

Hassallidin A, a glycosylated lipopeptide with antifungal activity from the cyanobacterium Hassallia sp

Hassallidin A (1), a new antifungal glycosylated lipopeptide, was isolated from an epilithic cyanobacterium collected in Bellano, Italy, identified as Tolypothrix (basionym Hassallia) species. Chemical, mass spectrometric, and spectroscopic analyses, including one- and two-dimensional NMR, were performed to determine an esterified eight-residue cyclic peptide linked with a carbohydrate and a fatty acid residue. Chiral GC-MS analysis revealed the occurrence of the nonproteinogenic amino acids D-allo-Thr, D-Thr, D-Tyr, D-Gln, and dehydroaminobutyric acid (Dhb) within the peptide moiety. The additional components of hassallidin A could be identified as alpha,beta-dihydroxytetradecanoic acid (Dht) and mannose. This is the first report on a cyclic peptide of cyanobacterial origin that contains both a fatty acid and a carbohydrate moiety. Compound 1 exhibits antifungal activity against Aspergillus fumigatus and Candida albicans with MIC values of 4.8 microg/mL for both test organisms.

Rapid screening and dereplication of bacterial isolates from marine sponges of the sula ridge by intact-cell-MALDI-TOF mass spectrometry (ICM-MS)

Rapid grouping of bacterial isolates is critical in comprehensive microbial studies of environmental samples or screening programmes e.g. in unknown marine environments where large numbers of strains have to be isolated on different growth media. Sets of bacteria have been cultured from the marine sponges Isops phlegraei, Haliclona sp. 1, Phakellia ventilabrum and Plakortis sp. growing at a depth of about 300 m on the Sula Ridge close to the Norwegian coast. We employed Intact-Cell MALDI-TOF (ICM) mass spectrometry to achieve a rapid proteometric clustering of a subset of the strain collection including 456 isolates. Cluster analysis of mass spectra resolved the strains into 11 groups corresponding to species of Alteromonas (15), Bacillus (3), Colwellia (31), Erythrobacter (19), Marinobacter (14), Marinococcus (6), Pseudoalteromonas (297), Pseudomonas (56), Roseobacter (3), Sphingomonas (2) and Vibrio (10) as verified by 16 S rDNA analysis. A further discrimination into subgroups was demonstrated for different isolates from the genus Pseudoalteromonas. The approach described here permits the rapid identification of isolates for dereplication, and the selection of strains representing rare species for subsequent characterization.

Pr�valenz sexueller Probleme bei Medizinstudentinnen

Female sexual dysfunction and even female sexual function are widely unknown. We therefore evaluated the sexual behaviour of younger and older women using a questionnaire. A total of 998 young women entered the study at Hannover Medical school. They were between 19 and 43 years old (median 24 years), and 64% answered the questionnaire. A total of 97.1% of the female students were heterosexual, 1.6% were lesbians and 1.3% were bisexual. Lack of sexual intercourse in the previous month was recorded by 21.1%, while 21.3% recorded intercourse 1-3 times a month, 46.8% 1-3 times a week and 5.5% daily. Adverse reactions to sexual situations were reported by 25% of the women, 20.5% had a negative perception for special partners or circumstances. Some 55% of the evaluated women were satisfied with their sexual life in the last month, 20% were fairly satisfied and 21% were un-satisfied. This study of a selected population of medical students shows a wide variety of sexual problems with a high prevalence of different disorders.

Metal-ion induced conformational changes in alkaline phosphatase from E. coli assessed by limited proteolysis

Alkaline phosphatase (AP) displays significant structural changes during metal-ion binding, supporting cooperative interactions between the subunits of the dimeric enzyme. Here, we present data on the dynamic properties of AP from E. coli, and characterize the structural changes that accompany variations in metal-ion content, combining limited proteolysis and MALDI-TOF mass spectrometry. Limited proteolysis revealed an internal cleavage site at Arg-293, reflecting a position of conformational flexibility supporting subunit communication essential for catalysis. A specific shielding of a region distant from the metal-binding site has been demonstrated, implying transmission of conformational changes, induced by metal-ion binding to the adjacent subunit, across the subunit interface.

ATPase activity of non-ribosomal peptide synthetases

Adenylation domains of non-ribosomal peptide synthetases (NRPS) catalyse the formation of aminoacyl adenylates, and in addition synthesize mono- and dinucleoside polyphosphates. Here, we show that NRPS systems furthermore contain an ATPase activity in the range of up to 2 P(i)/min. The hydrolysis rate by apo-tyrocidine synthetase 1 (apo-TY1) is enhanced in the presence of non-cognate amino acid substrates, correlating well with their structural features and the diminishing adenylation efficiency. A comparative analysis of the functional relevance of an analogous sequence motif in P-type ATPases and adenylate kinases (AK) allowed a putative assignment of the invariant aspartate residue from the TGDLA(V)R(K) core sequence in NRPS as the Mg(2+) binding site. Less pronounced variations in ATPase activity are observed in domains with relaxed amino acid specificity of gramicidin S synthetase 2 (GS2) and delta-(L-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS), known to produce a set of substitutional variants of the respective peptide product. These results disclose new perspectives about the mode of substrate selection by NRPS.

Nonribosomal peptide synthetases-evidence for a second ATP-binding site

delta-(L-alpha-Aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS) catalyses, via the protein thiotemplate mechanism, the nonribosomal biosynthesis of the penicillin and cephalosporin precursor tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV). The complete and fully saturated biosynthetic system approaches maximum rate of product generation with increasing ATP concentration. Nonproductive adenylation of ACVS, monitored utilising the ATP-[32P]PP(i) exchange reaction, has revealed substrate inhibition with ATP. The kinetic inhibition pattern provides evidence for the existence of a second nucleotide-binding site with possible implication in the regulatory mechanism. Under suboptimal reaction conditions, in the presence of MgATP(2-), L-Cys and inorganic pyrophosphatase, ACVS forms adenosine(5')tetraphospho(5')adenosine (Ap(4)A) from the reverse reaction of adenylate formation involving a second ATP molecule. The potential location of the second ATP binding site was deduced from sequence comparisons and molecular visualisation in conjunction to data obtained from biochemical analysis.

Dipeptide synthesis by an isolated adenylate-forming domain of non-ribosomal peptide synthetases (NRPS)

A deletion mutant of tyrocidine synthetase 1 (DeltaDeltaTY1), comprising the adenylation domain of TY1 as an independent functional adenylate-forming unit, was used to investigate the ability of the adenylation domain in non-ribosomal peptide synthetases to catalyse peptide bond formation from the aminoacyl adenylate intermediate. The results demonstrate that only one substrate amino acid needs to be activated as an aminoacyl adenylate. In view of the potential exploitation of peptide synthetases for enzymatic synthesis of dipeptides of choice, it is important to note that this does not necessarily require a dimodular construct or an intermediate acyl transfer step.

Synthesis of (di)adenosine polyphosphates by non-ribosomal peptide synthetases (NRPS)

In response to nutritional stress conditions, Bacillus brevis produces the cyclodecapeptide antibiotic tyrocidine via tyrocidine synthetase, a multifunctional non-ribosomal peptide synthetase. The apo-form of tyrocidine synthetase 1 forms adenosine (5')tetraphospho(5')adenosine, when incubated with MgATP(2-), amino acid and inorganic pyrophosphatase. The synthesis is an intrinsic property of the adenylation domain, is strictly dependent upon the amino acid, and proceeds from a reverse reaction of adenylate formation involving a second ATP molecule. In the presence of tri- or tetrapolyphosphate preferential synthesis of adenosine 5'-tetraphosphate and adenosine 5'-pentaphosphate occurs, respectively. A potential involvement of adenosine (5')-n-phospho(5')adenosine in the regulation of the biosynthetic process has been suggested.