Understanding oligomerization in 3α-hydroxysteroid dehydrogenase/carbonyl reductase from Comamonas testosteroni: An in silico approach and evidence for an active protein

3alpha-Hydroxysteroid dehydrogenase/carbonyl reductase (3alpha-HSD/CR) from Comamonas testosteroni belongs to the short chain dehydrogenase/reductase (SDR) protein superfamily and catalyzes the oxidoreduction of a variety of steroid substrates, including the steroid antibiotic fusidic acid. The enzyme also mediates the carbonyl reduction of non-steroidal aldehydes and ketones such as a novel insecticide. It is suggested that 3alpha-HSD/CR contributes to the bioremediation of natural and synthetic toxicants by C. testosteroni. Crystallization and structure analysis showed that 3alpha-HSD/CR is active as a dimer. Dimerization takes place via an interface axis which has exclusively been observed in homotetrameric SDRs but never in the structure of a homodimeric SDR. The formation of a tetramer is blocked in 3alpha-HSD/CR by the presence of a predominantly alpha-helical subdomain which is missing in all other SDRs of known structure. For example, 3alpha/20beta-HSD from Streptomyces hydrogenans exhibits two main subunit interfaces arranged about two non-crystallographic two-fold axes which are perpendicular to each other and referred to as P and Q. This mode of dimerization is, however, sterically impossible in 3alpha-HSD/CR because of a 28 amino acids insertion into the classical Rossmann-fold motif between strand betaE and helix alphaF. This insertion is masking helices alphaE and alphaF, thus preventing the formation of a four helix bundle and enables the dimerization via a P-axis interface. This type of dimerization in SDRs has never been observed in a crystal structure so far. The aim of this study was to investigate whether the lack of this predominantly alpha-helical subdomain keeps 3alpha-HSD/CR to be an active enzyme and whether, by an in silico approach, the formation of a homotetramer or even a novel oligomerization mode can be expected. Redesign of this interface was performed on the basis of site directed mutagenesis and according to other SDR structures by an approach combining "in silico" and "wet chemistry". Simulations of sterical and structural effects after different mutations, by applying a combination of homology modelling and molecular dynamic simulations, provided an effective tool for extensive mutagenesis studies and indicated the possibility of tetramer formation of truncated 3alpha-HSD/CR. In addition, despite lacking the extra loop domain, mutant 3alpha-HSD/CR was shown to be active towards a variety of standard substrates.

Typisierung beim HLA-Matching

Matching of human leukocyte antigens of donors and recipients (HLA matching) plays a significant role in kidney, heart, lung, and stem cell transplantation. New data demonstrate that HLA matching also significantly prolongs the survival of corneal grafts. The reasons for the late recognition of the significance of HLA matching in corneal transplantation are on the one hand the immune privilege of the eye, which allows corneal transplantation under certain conditions without immunosuppressive therapy, and on the other hand highly erroneous serological typing. Recent molecular DNA typing is almost without errors, and the selection of grafts on the basis of results obtained using this method will improve the long-time survival of future corneal grafts. Today, there are several reasons arguing for the general practice of HLA matching in keratoplasty.

[Incidence of hip fracture in Germany--person-related analysis of health insurance population]

BACKGROUND AND PURPOSE

An increasing number of hip fractures were reported world wide during the last decades. Up to now incidence data are rare for Germany. The aim of this study is to determine actual person-related age- and sex-specific rates of hip fractures in Germany.

METHODS

The linkable and person-specific but non-identifying database of a German statutory health insurance company, Gmuender ErsatzKasse (GEK), was used. All subjects who were admitted to hospital with a primary diagnosis of hip fracture (ICD-10: S72.0-S72.2) in 2004 were identified. Incidence rate ratios (IRR), age- and sex-specific rates (per 1000 person-years) were calculated. Annual numbers of hip fractures for all persons covered by statutory health insurances (Gesetzliche Krankenversicherung- GKV) and the German population were estimated.

RESULTS

The incidence of hip fracture increases exponentially with age. Hip fractures occur 129 times more often (IRR: 129.07; 95 % CI: 66.55 - 269.78) in women aged 90 - 94 years and 79 times more often (IRR: 78.97; 95 % CI: 30.02 - 185.87) in men aged 90 - 94 years compared to those aged 50 - 54 years. Approximately 101 037 (95 % CI: 91 779 - 110 294) persons are annually admitted to hospital in Germany due to this event.

CONCLUSION

Hip fractures are common in the elderly and especially in women. Because of demographic changes and a possible secular trend an increasing number of hip fractures are to be expected in the future.

Multicenter-study of operative treatment of intraligamentous tears of the anterior cruciate ligament in children and adolescents: comparison of four different techniques

Tears of the anterior cruciate ligament in skeletally immature patients were operated with four different methods and their outcome compared to each other. Sixty-eight patients (33 males, 35 females), mean 12.5 years, were treated in four different centers from 1984 to 2001. Twenty-eight patients underwent the ACL-reconstruction with hamstring grafts, 16 patients with bone-patella-bone autografts, 12 patients with quadriceps grafts and 12 patients with facia lata. The mean follow-up was 32 months. Postoperative evaluation included radiographs, KT-1000/2000 stability measurements, Lysholm score, The Tegner activity scale and IKDC score. Neither leg length discrepancy nor angular deformities were noted. Mean KT-1000 difference was 2.1 mm, mean postoperative Lysholm knee score 93.3, IKDC 87% normal or nearly normal. The Tegner index decreased from 6.6 to 5.7. In total, six patients developed instability due to an adequate trauma 1 year after the index operation. Two patients showed mild arthrotic changes. All but two patients were able to return to the same level of preoperative sports participation. None of the four methods studied showed major differences in outcome compared to the other. No growth disturbance could be noted.

Inclusion body anatomy and functioning of chaperone-mediated in vivo inclusion body disassembly during high-level recombinant protein production in Escherichia coli

During production in recombinant Escherichia coli, the human basic fibroblast growth factor (hFGF-2) partly aggregates into stable cytoplasmic inclusion bodies. These inclusion bodies additionally contain significant amounts of the heat-shock chaperone DnaK, and putative DnaK substrates such as the elongation factor Tu (ET-Tu) and the metabolic enzymes dihydrolipoamide dehydrogenase (LpdA), tryptophanase (TnaA), and d-tagatose-1,6-bisphosphate aldolase (GatY). Guanidinium hydrochloride induced disaggregation studies carried out in vitro on artificial aggregates generated through thermal aggregation of purified hFGF-2 revealed identical disaggregation profiles as hFGF-2 inclusion bodies indicating that the heterogenic composition of inclusion bodies did not influence the strength of interactions of hFGF-2 in aggregates formed in vivo as inclusion bodies compared to those generated in vitro from native and pure hFGF-2 through thermal aggregation. Compared to unfolding of native hFGF-2, higher concentrations of denaturant were required to dissolve hFGF-2 aggregates showing that more energy is required for disruption of interactions in both types of protein aggregates compared to the unfolding of the native protein. In vivo dissolution of hFGF-2 inclusion bodies was studied through coexpression of chaperones of the DnaK and GroEL family and ClpB and combinations thereof. None of the chaperone combinations was able to completely prevent the initial formation of inclusion bodies, but upon prolonged incubation mediated disaggregation of otherwise stable inclusion bodies. The GroEL system was particularly efficient in inclusion body dissolution but did not lead to a corresponding increase in soluble hFGF-2 rather was promoting the proteolysis of the recombinant growth factor. Coproduction of the disaggregating DnaK system and ClpB in conjunction with small amounts of the chaperonins GroELS was most efficient in disaggregation with concomitant formation of soluble hFGF-2. Thus, fine-balanced coproduction of chaperone combinations can play an important role in the production of soluble recombinant proteins with a high aggregation propensity not through prevention of aggregation but predominantly through their disaggregating properties.

[Arthroscopic Bankart operation using absorbable suture anchors]

OBJECTIVE

Arthroscopic refixation of the labrum-ligament complex at the glenoid.

INDICATIONS

Posttraumatic anterior or anterior-inferior shoulder instability with Bankart or ALPSA lesion (anterior labral periosteal sleeve avulsion).

CONTRAINDICATIONS

Atraumatic shoulder instability. Instabilities due to blunted or frayed degeneration of the labrum-ligament complex. HAGL lesion (humeral avulsion of the glenohumeral ligaments) with humeral detachment of the glenohumeral ligaments. Larger bony glenoid defects.

SURGICAL TECHNIQUE

Mobilization of the labrum-ligament complex from the neck of the glenoid, superior tightening and refixation at the glenoid rim with the aid of absorbable suture anchors.

POSTOPERATIVE MANAGEMENT

Immobilization of the affected arm for 4 weeks in an immobilization bandage with abduction pillows. Daily pendulum exercises. Active flexion up to 70 degrees and abduction up to 40 degrees, all in neutral or internal rotation. Avoidance of external rotation for a total of 6 weeks.

RESULTS

From January 1999 to December 2001, 58 patients with a Bankart or ALPSA lesion were treated with arthroscopic shoulder stabilization using absorbable suture anchors and slowly absorbable braided sutures. 56 patients underwent a follow-up clinical examination after, on average, 31 months (24-48 months). None of these patients had suffered more than five shoulder dislocations before the operation (average 2.8). Of the intraoperative lesions, a plain Bankart lesion was present in twelve patients (21.4%), 44 patients had an ALPSA lesion (78.6%), of which one in two were combined with an SLAP 2 or SLAP 3 lesion (superior labrum from anterior to posterior). In the evaluation using the Rowe Score, there was an excellent result for 40 patients (71.4%), and a good result for twelve (21.4%). Four patients suffered a repeat dislocation and were therefore classified as poor results (7.2%).

Bendamustine in combination with thalidomide and prednisolone (BPT) in patients with refractory or relapsed multiple myeloma: Results of a phase I clinical trial

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Background: Thalidomide is an active single agent in advanced relapsed or refractory multiple myeloma (MM). Combination of low dose thalidomide with bendamustine and prednisolone might be a way to maintain efficacy of the drug without dose limiting toxicity (DLT). Methods: The treatment consists of a fixed dose of bendamustine (60mg/qm) day 1, 8, and 15 and prednisolone (100 mg) day 1, 8, 15, and 22. At the same time, thalidomide was given in patients cohorts with escalating doses, starting with 50 mg to a maximum of 200 mg daily. 8 patients (4 after conventional chemotherapy and 4 after APBSCT) were enrolled at each dose level. Cycles were repeated every 28 days for a minimum of 2 and a maximum of 10 cycles until a maximal response was achieved, a DLT or a disease progression were observed. 23 patients ( 8 in the first dose level with 50 mg thalidomide, 8 in the second dose level with 100 mg and 7 patients in the third dose level with 200 mg) are enrolled until now. The number of prior treatment regimens was 2 or more in all patients. 6 patients were refractory for the last treatment. Median age was 67 years (range: 40 - 78). Results: All patients completed 2 cycles of BPT-treatment and were hence evaluable. Response was assessed using EBMT criteria modified to include near complete remission (nCR) and very good partial remission (VGPR). 20 of 23 patients responded after at least 2 cycles of chemotherapy with 3 CR, 5 VGPR, 11 PR and 2 MR. 2 patients had stable disease. With a median follow up of ten months, EFS and OS at twelfe months were 36 % and 85 %, respectively. Most common site effects were constipation (10 patients WHO grade 1, 8 patients WHO grade 2), polyneuropathy (14 patients WHO grade 1, 2 patients WHO grade 2) and somnolence (4 patients WHO grade 1). None of the 23 patients developed dose-limiting hematoxicity as defined by an ANC < 1,0 Gpt/l for > 7 days or an ANC < 0,5 Gpt/l for > 3 days or platelet count < 25 Gpt/l. Short neutropenia was reported in 8 patients (WHO grade 3 and 4) but no thrombocytopenia was observed. Conclusions: BPT with a dose between 50 and 200 mg thalidomide daily is well tolerated in patients with relapsed or refractory MM.

No significant financial relationships to disclose.

Gelatinase B [matrix metalloproteinase (MMP)-9] and collagenases (MMP-8/-13) are upregulated in cerebrospinal fluid during aseptic and bacterial meningitis in children

We investigated the protein expression of gelatinases [matrix metalloproteinase (MMP)-2 and -9] and collagenases (MMP-8 and -13) in cerebrospinal fluid (CSF) from patients with bacterial (BM, n = 17) and aseptic (AM, n = 14) meningitis. In both, MMP-8 and -9 were increased in 100% of patients, whereas MMP-13 was detectable in 53% and 82% respectively. Three patients with clinical signs of meningitis, without CSF pleocytosis, scored positive for all three MMPs. MMP-8 appeared in two isoforms, granulocyte-type [polymorphonuclear cell (PMN)] and fibroblast/macrophage (F/M) MMP-8. Analysis of kinetic changes from serial lumbar punctures showed that these MMPs are independently regulated, and correlate only partly with CSF cytosis or levels of the endogenous inhibitor, tissue inhibitor of matrix metalloproteinase-1. In vitro, T cells, peripheral blood mononuclear cells (PBMCs) and granulocytes (PMN) release MMP-8 and -9, whereas MMP-13 could be found only in the former two cell types. Using models of exogenous (n-formyl-Met-Leu-Phe, T cell receptor cross-linking) and host-derived stimuli (interleukin-2), the kinetics and the release of the MMP-8, -9 and -13 showed strong variation between these immune cells and suggest release from preformed stocks. In addition, MMP-9 is also synthesized de novo in PBMCs and T cells. In conclusion, invading immune cells contribute only partially to MMPs in CSF during meningitis, and parenchymal cells are an equally relevant source. In this context, in patients with clinical signs of meningitis, but without CSF pleocytosis, MMPs seem to be a highly sensitive marker for intrathecal inflammation. The present data support the concept that broad-spectrum enzyme inhibition targeting gelatinases and collagenases is a potential strategy for adjunctive therapy in infectious meningitis.

Silica-Based Mesoporous Organic–Inorganic Hybrid Materials

Mesoporous organic-inorganic hybrid materials, a new class of materials characterized by large specific surface areas and pore sizes between 2 and 15 nm, have been obtained through the coupling of inorganic and organic components by template synthesis. The incorporation of functionalities can be achieved in three ways: by subsequent attachment of organic components onto a pure silica matrix (grafting), by simultaneous reaction of condensable inorganic silica species and silylated organic compounds (co-condensation, one-pot synthesis), and by the use of bissilylated organic precursors that lead to periodic mesoporous organosilicas (PMOs). This Review gives an overview of the preparation, properties, and potential applications of these materials in the areas of catalysis, sorption, chromatography, and the construction of systems for controlled release of active compounds, as well as molecular switches, with the main focus being on PMOs.

Posttraumatic anterior-inferior instability of the shoulder: arthroscopic findings and clinical correlations

INTRODUCTION

The main purpose of our study was to evaluate intra-articular lesions in glenohumeral-instability with arthroscopy and correlate them with clinical findings as well as history of instability.

MATERIAL AND METHODS

In this prospective multi-centre study, we evaluated arthroscopic findings in 303 patients with posttraumatic anterior-inferior instability of the shoulder. The study cohort was divided into 2 groups: patients with a history of one dislocation (Group 1, n=61, 20.1%) and patients with a history of more than one dislocation (Group 2, n=242, 79.9%).

RESULTS

In Group 1, 37 patients had an IGHL-lesion, 31 a MGHL-lesion and 41 a Hill-Sachs lesion. In Group 2, 182 patients had an IGHL-lesion, 172 a MGHL-lesion and 203 a Hill-Sachs lesion. The percentage of lesions in Group 2 (IGHL-75.2%, MGHL-71.1%, Hill-Sachs-83.9%) was significantly higher than in Group 1 (IGHL-60.7%, MGHL-50.8%, Hill-Sachs-67.2%, P=0.0233, P=0.0026, and P=0.0033, respectively). Within Group 2 we found significantly more Hill-Sachs-lesions with a history of an increasing number of recurrences (P=0.0436). We also found an increase of IGHL- and MGHL-lesions with an increasing number of recurrences, but this difference was not significant. The distribution of lesion types of the anterior labrum-ligament complex showed no significant difference between the two groups, apart from a higher incidence of ALPSA-lesions within Group 2 (34.7% versus 18.0% in Group 1). The results of this study show that recurrences after primary posttraumatic anterior-inferior shoulder dislocation cause increasing ligamental damage as well as increasing Hill-Sachs lesions within the gleno-humeral joint.

CONCLUSION

Thus we conclude that early surgical stabilization after posttraumatic anterior-inferior shoulder dislocation is necessary to prevent increasing damage within the shoulder joint.

Neugebrauch von Benzodiazepinen und das Risiko einer proximalen Femurfraktur

Benzodiazepines appear to increase the incidence of hip fractures. Their role as a time-dependent risk factor remains unclear. We therefore conducted a case-crossover study to determine whether the new use of benzodiazepines is associated with a rise in hip fractures. We analysed 49 months of the statutory health insurance Gmünder Ersatzkasse (GEK) and enrolled all first hip fractures. The index date was the day of hospital admission. Exposure to new use of benzodiazepines was compared within the five periods preceding the index date. Out of 1630 subjects, 223 (13.7%) had at least one prescription of benzodiazepines in the preceding 150 days before the index date, 74 (4.5%) of them as a first prescription. The average age of the population was 79.8 years (SD: 7.7). Odds ratio (OR) of hip fracture was highest during the initial 5 days of new use (OR: 3.43; 95% CI 1.15-10.20) and then declined to a non-significant OR of 1.59 (95% CI 0.96-2.63) after 30 days. In conclusion, the start of a new benzodiazepine is associated with an increased risk of hip fractures. However, the population attributable risk (PAR) and, therefore, the percentage of preventable events is small (PAR: 0.55%; 95% CI 0.05-1.06%).

Oxygen-limited control of methanol uptake for improved production of a single-chain antibody fragment with recombinant Pichia pastoris

The yeast Pichia pastoris is a suitable production system for recombinant proteins due to its strong methanol-inducible AOX1 promoter. A key parameter of the production process is the specific methanol uptake rate. To control the methanol uptake and simultaneously maintain a constant methanol concentration during the production phase, two strategies were developed to generate purposeful oxygen limitation and to feed-forward control the specific methanol uptake rate into the optimum range. First, the cell density at induction was adjusted by prolonged preinduction glycerol feeding. Alternatively, the airflow rate was restricted and increased in parallel with the biomass. While the product accumulation started 20 h earlier with the first approach, the specific production rate of a single-chain antibody fragment was three times higher in the latter case. After 70 h of production, both schemes yielded product concentrations in the gram-per-liter range. Moreover, they release the requirement for dosage of pure oxygen and thereby can facilitate the scale-up of the production process. The different production profiles indicate that the impact of specific methanol uptake rate on protein production by recombinant P. pastoris depends on the control mode.

Periodic mesoporous organosilicas (PMOs): past, present, and future

Periodic mesoporous organosilicas (PMOs) represent a new class of organic-inorganic hybrid materials suitable for a broad range of applications such as chromatography, catalysis, sensing and microelectronics. Unlike in organic functionalized mesoporous silica phases obtained via grafting or co-condensation procedures the organic groups in PMOs are direct parts of the 3D framework structure, thus giving raise to enormous possibilities to tune their chemical and physical properties in designated ways by varying the structure of the precursors. In this review the distinctive features of PMOs are discussed, the latest developments concerning compositions, structures, morphologies and potential applications are figured out and finally a brief outlook of future aspects is given.