Imaging plasma formation in isolated nanoparticles with ultrafast resonant scattering

We have recorded the diffraction patterns from individual xenon clusters irradiated with intense extreme ultraviolet pulses to investigate the influence of light-induced electronic changes on the scattering response. The clusters were irradiated with short wavelength pulses in the wavelength regime of different 4d inner-shell resonances of neutral and ionic xenon, resulting in distinctly different optical properties from areas in the clusters with lower or higher charge states. The data show the emergence of a transient structure with a spatial extension of tens of nanometers within the otherwise homogeneous sample. Simulations indicate that ionization and nanoplasma formation result in a light-induced outer shell in the cluster with a strongly altered refractive index. The presented resonant scattering approach enables imaging of ultrafast electron dynamics on their natural timescale.

Limits of Life and the Habitability of Mars: The ESA Space Experiment BIOMEX on the ISS

BIOMEX (BIOlogy and Mars EXperiment) is an ESA/Roscosmos space exposure experiment housed within the exposure facility EXPOSE-R2 outside the Zvezda module on the International Space Station (ISS). The design of the multiuser facility supports-among others-the BIOMEX investigations into the stability and level of degradation of space-exposed biosignatures such as pigments, secondary metabolites, and cell surfaces in contact with a terrestrial and Mars analog mineral environment. In parallel, analysis on the viability of the investigated organisms has provided relevant data for evaluation of the habitability of Mars, for the limits of life, and for the likelihood of an interplanetary transfer of life (theory of lithopanspermia). In this project, lichens, archaea, bacteria, cyanobacteria, snow/permafrost algae, meristematic black fungi, and bryophytes from alpine and polar habitats were embedded, grown, and cultured on a mixture of martian and lunar regolith analogs or other terrestrial minerals. The organisms and regolith analogs and terrestrial mineral mixtures were then exposed to space and to simulated Mars-like conditions by way of the EXPOSE-R2 facility. In this special issue, we present the first set of data obtained in reference to our investigation into the habitability of Mars and limits of life. This project was initiated and implemented by the BIOMEX group, an international and interdisciplinary consortium of 30 institutes in 12 countries on 3 continents. Preflight tests for sample selection, results from ground-based simulation experiments, and the space experiments themselves are presented and include a complete overview of the scientific processes required for this space experiment and postflight analysis. The presented BIOMEX concept could be scaled up to future exposure experiments on the Moon and will serve as a pretest in low Earth orbit.

Cellular Responses of the Lichen Circinaria gyrosa in Mars-Like Conditions

Lichens are extremely resistant organisms that colonize harsh climatic areas, some of them defined as "Mars-analog sites." There still remain many unsolved questions as to how lichens survive under such extreme conditions. Several studies have been performed to test the resistance of various lichen species under space and in simulated Mars-like conditions. The results led to the proposal that Circinaria gyrosa (Lecanoromycetes, Ascomycota) is one of the most durable astrobiological model lichens. However, although C. gyrosa has been exposed to Mars-like environmental conditions while in a latent state, it has not been exposed in its physiologically active mode. We hypothesize that the astrobiological test system "Circinaria gyrosa," could be able to be physiologically active and to survive under Mars-like conditions in a simulation chamber, based on previous studies performed at dessicated-dormant stage under simulated Mars-like conditions, that showed a complete recover of the PSII activity (Sánchez et al., 2012). Epifluorescence and confocal laser scanning microscopy (CLSM) showed that living algal cells were more abundant in samples exposed to niche conditions, which simulated the conditions in micro-fissures and micro-caves close to the surface that have limited scattered or time-dependent light exposure, than in samples exposed to full UV radiation. The medulla was not structurally affected, suggesting that the niche exposure conditions did not disturb the lichen thalli structure and morphology as revealed by field emission scanning electron microscopy (FESEM). In addition, changes in the lichen thalli chemical composition were determined by analytical pyrolysis. The chromatograms resulting from analytical pyrolysis at 500°C revealed that lichen samples exposed to niche conditions and full UV radiation consisted primarily of glycosidic compounds, lipids, and sterols, which are typical constituents of the cell walls. However, specific differences could be detected and used as markers of the UV-induced damage to the lichen membranes. Based on its viability responses after rehydration, our study shows that the test lichen survived the 30-day incubation in the Mars chamber particularly under niche conditions. However, the photobiont was not able to photosynthesize under the Mars-like conditions, which indicates that the surface of Mars is not a habitable place for C. gyrosa.

Electronic and Optical Properties of Methylated Adamantanes

Recent theoretical work has identified functionalized diamondoids as promising candidates for the tailoring of fluorescent nanomaterials. However, experiments confirming that optical gap tuning can be achieved through functionalization have, up until now, found only systems where fluorescence is quenched. We address this shortcoming by investigating a series of methylated adamantanes. For the first time, a class of functionalized diamondoids is shown to fluoresce in the gas phase. In order to understand the evolution of the optical and electronic structure properties with degree of functionalization, photoelectron spectroscopy was used to map the occupied valence electronic structure, while absorption and fluorescence spectroscopies yielded information about the unoccupied electronic structure and postexcitation relaxation behavior. The resulting spectra were modeled by (time-dependent) density functional theory. These results show that it is possible to overcome fluorescence quenching when functionalizing diamondoids and represent a significant step toward tailoring the electronic structure of these and other semiconductor particles in a manner suitable to applications.

Recombination-Enhanced Surface Expansion of Clusters in Intense Soft X-Ray Laser Pulses

We studied the nanoplasma formation and explosion dynamics of single large xenon clusters in ultrashort, intense x-ray free-electron laser pulses via ion spectroscopy. The simultaneous measurement of single-shot diffraction images enabled a single-cluster analysis that is free from any averaging over the cluster size and laser intensity distributions. The measured charge state-resolved ion energy spectra show narrow distributions with peak positions that scale linearly with final ion charge state. These two distinct signatures are attributed to highly efficient recombination that eventually leads to the dominant formation of neutral atoms in the cluster. The measured mean ion energies exceed the value expected without recombination by more than an order of magnitude, indicating that the energy release resulting from electron-ion recombination constitutes a previously unnoticed nanoplasma heating process. This conclusion is supported by results from semiclassical molecular dynamics simulations.

Correction: Size and shape dependent photoluminescence and excited state decay rates of diamondoids

Correction for ‘Size and shape dependent photoluminescence and excited state decay rates of diamondoids’ by Robert Richter et al., Phys. Chem. Chem. Phys., 2014, 16, 3070–3076.

Generation and structure of extremely large clusters in pulsed jets

Extremely large xenon clusters with sizes exceeding the predictions of the Hagena scaling law by several orders of magnitude are shown to be produced in pulsed gas jets. The cluster sizes are determined using single-shot single-particle imaging experiments with short-wavelength light pulses from the free-electron laser in Hamburg (FLASH). Scanning the time delay between the pulsed cluster source and the intense femtosecond x-ray pulses first shows a main plateau with size distributions in line with the scaling laws, which is followed by an after-pulse of giant clusters. For the extremely large clusters with radii of several hundred nanometers the x-ray scattering patterns indicate a grainy substructure of the particles, suggesting that they grow by cluster coagulation.

Hidden charge states in soft-x-ray laser-produced nanoplasmas revealed by fluorescence spectroscopy

Highly charged ions are formed in the center of composite clusters by strong free-electron laser pulses and they emit fluorescence on a femtosecond time scale before competing recombination leads to neutralization of the nanoplasma core. In contrast to mass spectrometry that detects remnants of the interaction, fluorescence in the extreme ultraviolet spectral range provides fingerprints of transient states of high energy density matter. Spectra from clusters consisting of a xenon core and a surrounding argon shell show that a small fraction of the fluorescence signal comes from multiply charged xenon ions in the cluster core. Initially, these ions are as highly charged as the ions in the outer shells of pure xenon clusters with charge states up to at least 11+.

The influence of a single thiol group on the electronic and optical properties of the smallest diamondoid adamantane

At the nanoscale, the surface becomes pivotal for the properties of semiconductors due to an increased surface-to-bulk ratio. Surface functionalization is a means to include semiconductor nanocrystals into devices. In this comprehensive experimental study we determine in detail the effect of a single thiol functional group on the electronic and optical properties of the hydrogen-passivated nanodiamond adamantane. We find that the optical properties of the diamondoid are strongly affected due to a drastic change in the occupied states. Compared to adamantane, the optical gap in adamantane-1-thiol is lowered by approximately 0.6 eV and UV luminescence is quenched. The lowest unoccupied states remain delocalized at the cluster surface leaving the diamondoid's negative electron affinity intact.

Prevention of thromboembolism with low-molecular-weight heparin in orthopedic surgery: a 5-year experience

A regimen of prophylaxis of thromboembolism with low molecular weight heparin (LMWH) and unfractionated heparin (UFH) in orthopedic surgery is presented. Over a 5-year period, 11,905 patients have been operated in all fields of orthopedic surgery in a big trauma center. In 498 cases, deep vein thrombosis (DVT) was clinically suspected and phlebography was performed: 122 patients had confirmed DVT (rate 0.98%); 59.8% of the DVT were limited to the calf. Nineteen pulmonary embolisms (rate 0.16%) were diagnosed (3 lethal). Heparin-induced thrombocytopenia type II was diagnosed in 12 of 122 patients. Only one of these had received LMWH. The related rates of DVT were highest for tibial head fractures (12.4%), total knee replacement (6.7%), and multiple trauma (6.4%). The extent of DVT was most severe in multiple trauma. The results proved the regimen to be of good clinical use and showed that more attention has to be paid to fractures, especially of the knee; and to patients with multiple injuries.

Three-dimensional load measurements in an external fixator

On the basis of a six-degree-of-freedom adjustable fracture reduction hexapod external fixator, a system which can be used for measuring axial and shear forces as well as torsion and bending moments in the fixator in vivo was developed. In a pilot study on 9 patients (7 fresh fractures and 2 osteotomies of the tibia), the load in the fixator during the healing process was measured after 2, 4, 8 and 12 weeks and at fixator removal. The measured values enabled both the type of fracture to be determined as well as the monitoring of the healing process. In well-reduced type A3 fractures small axial (direction of the bone axis) forces were found in the fixator. A2, B2 and C3 fractures showed distinct axial forces, which decreased during the healing process, according to an increasing load transfer over the bone. Bending moments in the fixator showed good correspondence with the clinical healing process, except in the case of a C3 fracture. A combination of bending moment and axial force proved to be particularly suitable to assess fracture healing. In transverse fractures, the well-known resorption phenomenon of bone in the fracture gap at approximately 4 weeks was detected by the system. Compared with other external fixator load measurements in vivo, the hexapod offers the advantage of being able to measure all forces and moments in the fixator separately and with a relatively simple mechanical arrangement. In our opinion, it will be possible to control fracture healing using this system, thereby minimizing radiation exposure from radiographs. Furthermore, the measurement system is a step towards the development of external fixator systems that enable automatic adjustments of the callus mechanical situation ("automatic dynamization") and inform the patients about the optimal weight bearing of their extremity ("intelligent fixator").

[Experiences in the treatment of midfacial fractures using a fixed-angle osteosynthetic system. Biomechanical results]

AIM

Fixed-angle osteosynthetic systems are characterized by mechanical "locking" of the osteosynthetic screw and plate. These systems have found increasing acceptance and use for osteosynthetic fixation and temporary reconstruction of the mandible. The aim of this study was to investigate the applicability and performance of fixed-angle systems in the treatment of midfacial fractures.

MATERIAL AND METHOD

A newly developed fixed-angle osteosynthetic plate system (smart lock) was compared to a conventional system using fresh human skulls. The iatrogenically produced zygomatic fractures of the human skulls were treated by osteosynthesis and biomechanically tested. Furthermore, in a dynamic test series, an artificial bone was subjected to an alternating force of 15 N of up to 1,000,000 cycles. The new screws and plates were subjected to further biomechanical tests.

RESULTS

The tests using the fixed-angle implants revealed that an increase of stability of up to 40% can be expected after osteosynthetic fixation. Furthermore, the plates resisted 1,000,000 cycles of alternating forces, whereby the conventional systems failed after 170,000 cycles on the average.

CONCLUSION

Fixed-angle systems, due to their construction, provide a high degree of stability even in thin bones of the midface. They appear to be promising for the treatment of midfacial fractures.

Dimensional variability of nonstandardized greater taper finger spreaders with matching gutta-percha points

AIM

The purpose of this research was to determine the compatibility and dimensional variability between nonstandardized gutta-percha points and matching finger spreaders.

METHODOLOGY

The diameters of nonstandardized gutta-percha points (n = 15) and matching finger spreaders (n = 15) from different manufacturers (Kerr, Dentsply Maillefer, Vereignigte Dentalwerke and Roeko) were determined and statistically analysed using a profile projector under a magnification of 50 x (+/- 0.002 mm).

RESULTS

The dimensions of the finger spreaders and gutta-percha cones were inconsistent. Of the 29 groups of nonstandardized gutta-percha cones evaluated, 22 had standard deviations larger than 0.020 at D1. The standard deviations at D11 were greater than at D1, with the exception of those manufactured by Roeko. Overall, nonstandardized gutta-percha cones made by VDW had the greatest dimensional consistency within each size group; the largest variations were seen in the Dentsply Maillefer gutta-percha points. The 13 sizes of nonstandardized finger spreaders were more consistent.

CONCLUSIONS

The results of this study show that corresponding sizes of nonstandardized finger spreaders and gutta-percha cones have statistically significant differences. There were large dimensional variations within sizes and discrepancies between the nominal size and actual size. Thus, these discrepancies may cause problems during root canal filling.

[Corrections using the hexapod]

The hexapod is a construction that has been subjected to a great deal of investigation in robotics for use in three-dimensional positioning. One use of it is for positioning of the cockpit in flight simulators. Application of the hexapod principle in the external fixator makes it possible to realize prescribed movements of bone fragments with a simple and stable design. The precise setting of the system requires software that has been developed and optimized for clinical use. Translations, axis corrections and rotations are possible individually and also in combinations for correction of complex deformities. The system has advantages, especially in the case of rotations around the longitudinal axis of the bone and in the realization of translation movements. Because the centres of rotation are taken into account by the mathematical calculations, the planning of corrections is simplified. The hexapod system is described, and its clinical application is presented with reference to case reports.

Fracture reduction and deformity correction with the hexapod Ilizarov fixator

A configuration for the Ilizarov external fixator with six distractors and 12 ball joints in the form of a hexapod was developed. The system allows for six degrees of freedom bone fragment displacement by controlling the distractors. Using this assembly, universal three-dimensional corrections or reductions are possible without the need for complicated joint mechanisms. The device was used in 16 patients: five had displaced tibial fractures with severe soft tissue damage, 10 had deformities or pseudarthroses subsequent to treatment of tibial fractures, and one had an axis deviation in the course of tibial lengthening. Translational (to 40 mm) and rotational deformities (to 33 degrees) were corrected. Final radiographic examinations after the correction procedure was complete showed median residual deformities of 3.5 mm (range, 0-5 mm) and 1 degree (range, 0 degree-4 degrees) in the anteroposterior projection and of 1.5 mm (range, 0-6 mm) and less than 1 degree (range, 0 degree-9 degrees) in the lateral projection. The construction is a useful and important addition to the Ilizarov fixator system. As a bone fixation device it is unique in that its optimal use depends on the availability of computer software.

Follow-up evaluation of open intra-articular fractures of the calcaneus

The results of a follow-up evaluation of open intra-articular calcaneal fractures are presented. A modified Merle d'Aubigné functional score and Zwipp radiographic score were used. A retrospective analysis of 35 patients with 36 open intra-articular fractures represents the basis of the study. At the time of follow-up examination (on average 44 months after the injury), 5 amputations of the affected extremity and 4 ankle arthrodeses had been carried out. The 23 patients still able to bear weight on the affected hindfoot and possessing a functional ankle joint were radiographically and functionally evaluated. No excellent results were documented. Only 6 good functional and 2 good radiographic outcomes were noted. In 17 instances, a poor functional or radiographic score was given. Devastating results were seen in the course of treatment of third-degree open joint depression or comminuted intra-articular fractures (n = 15): 9 cases of osteomyelitis, 5 amputations, 1 partial calcanectomy, 1 arthrodesis. An open reduction as part of the primary treatment (n = 6) led to local complications in all instances. The most favorable results were seen after nonoperative fracture management: complication-free course of treatment in 4 of 11 patients. All workmen's injuries led to a permanent disability, and these patients received compensation. The treatment and salvage of the soft-tissue envelope should be paramount in all therapeutic decisions. The fracture treatment must not further jeopardize these tissues. An aggressive operative treatment of local complications, including arthrodesis or amputation, is recommended.

[Aplasia of the articular process of the 2nd cervical vertebra]

The X-ray diagnosis of a contusion of the cervical spine showed unilateral aplasia of the inferior articular process of C2 in a 7-year-old boy. The literature, diagnosis and differential diagnosis are discussed.

[Transoral metal implant removal after ventral C2/C3 spondylodesis in pharyngo-vertebral fistula]

A 26-year-old man sustained a C2 arc fracture. Ventral spondylodesis using an H-plate was performed. The patient developed a pharyngovertebral fistula which remained undetected for 1 year. Spontaneous fusion of C3/C4 and osteolysis of the cortical block occurred. The fistula was demonstrated intraoperatively and the implant was transorally removed. No further problems occurred after this unusual method of treatment. The anatomy of the cervical spine, special problems of intensive care patients and the use of proper instrumentation are discussed.

[Dangers and risks of thoracic drainage at the accident site]

For several years it has been argued that a chest tube should be placed at the scene of an accident if thoracic trauma is suspected. However, during emergency treatment in hospital it has been observed that a high number of such tubes have been placed incorrectly. To validate this impression, we conducted a retrospective analysis of the clinical course of 33 trauma victims who had chest tubes placed at the scene of accident. It was found that 39.4% of the chest tubes were placed completely incorrectly and 21.2% required some correction; 39.4% were placed correctly. In two cases (6.1%) life-threatening complications developed because of the chest tube, necessitating a thoracotomy in 1 patient and repeated pericardial punction in the other. Based on the results of our study we believe that a more critical attitude should be adopted to the placement of chest tubes at the scene of the accident.

[Significance of isthmic spondylolisthesis in expert assessment of occupational disease of the lumbar spine]

In Germany, disc-related disease of the lumbar spine is eligible for workmen's compensation if caused by long-standing work requiring heavy lifting or carrying or extreme trunk-bending (BK 2108). The appraisal of causality is particularly difficult if conditions like isthmic spondylolisthesis preexist. 250 consecutive appraisals in nurses concerning the BK 2108 were analysed, 12 applicants (4.8%) had isthmic spondylolisthesis (4.6% of females and 5.9% of males). The literature about the natural history of isthmic spondylolisthesis is reviewed. A person who has isthmic spondylolisthesis is up to 25% more likely to have significant back trouble during his life than one who does not. Back pain in adults associated with spondylolisthesis is usually heralded by back pain in the late teens or early twenties. Progression of the slip is rarely seen after maturity. Due to the loss of protection by the posterior elements the disc is prone to premature degeneration which, however, does not become clinically apparent in most cases. Longstanding vocational heavy lifting or excessive stooping can negatively influence the natural history of isthmic spondylolisthesis. It can produce symptomatic disease in a person who would otherwise have remained asymptomatic, or it can cause a deterioration in those with preexisting symptoms. Criteria for the appraisal of causality are proposed. It is stressed that the course of the disease in relation to age and vocational strains has to be analysed in each individual case.

[Universal 3-dimensional correction and reposition with the ring fixator using the hexapod configuration]

A new configuration for the Ilisarov fixator with 6 distractors and 12 ball joints in the form of a hexapod is proposed. Using this assembly, a correction or reduction is possible with respect to any given point and axis in space. The primary position of the rings is not critical. The fixator system is statically determined and there is no stress between the longitudinal rods. Difficult corrections like those necessary for rotational deformities can be done without complicated joint mechanisms.

[The transparent tibia]

To keep damage to vascular and neural structure in the lower leg to a minimum when Ilizarov ring fixators are mounted, a transparent model of the lower leg has been designed and produced. In this model the course of the vascular and neural structures is shown anatomically correct relative to the bones of the lower leg. This model makes it easier to imagine the spatial relations and helps in correct placement of the Kirschner wires in the lower leg.

[Development and characterization of an absorbable temporary wound dressing]

Most of the temporary dressings used in the treatment of burns do not meet the objectives of a skin substitute concerning application, safety and comfort. Removal is often painful and traumatic and increases the risk of infection. Biodegradable polymers of lactic and caproic acid were developed as part of a research programme (BMFT/FRG 01 KG 8809/7), and chemical and physical properties were investigated. Films made of the copolymer material were characterized by structure, transparency, permeability, tensile strength, flexibility and degradation. The transparent films appeared increasingly opaque during hydrolysis. The water vapour permeance could be varied between 40 and 250 (40-136) ml/m2 per h (according to the method of measurement). The mechanical properties are characterized by a maximum elongation of > 2000% at 37 degrees C and a very low elastically modulus. When the results were compared with those of three established film dressings, no restriction was found in the aptitude of the material as a wound dressing.

[Mechanoreceptors in the distal aspects of the m. vastus medialis?]

Five cadavers were fixed in Jores' solution and alcohol. The distal parts of the medial vastus muscle and the medial parts of the patella ligament and of the capsule of the knee joint were prepared and histologically examined. Previous examinations had shown mechanoreceptors in the knee joint ligaments; the present study was designed to find whether mechanoreceptors could be identified in the anatomical structures mentioned, in which case an arthrotomy by the Payr access would interrupt the muscle reflexes. Only some mechanoreceptors in the medioventral parts of the knee joint capsule close to the tendon of the great muscle could be identified. Thus, when the Payr access is used there is no interruption of the sensibility transmitted by proprioceptors.

[Fracture treatment in the area of the tibia]

From May 1990 to March 1992 17 open and 6 closed fractures of tibia and fibula with second- to third-degree soft tissue injuries were treated by external fixation using the Ilisarov technique. In 14 patients this external fixation was used as the primary treatment. In nine cases it was used secondarily, mainly in patients transferred after stabilization with other internal or external devices. The mean duration of fixation for diaphyseal tibial fractures was 127 days and for metaphyseal fractures, 107 days. After removal of the fixation device, a brace was temporarily fitted for full weight-bearing. Disadvantages observed include less comfort for the patient and longer operation time compared to other external fixation systems. On the other hand, this method allows full weight-bearing soon after the operation and involves minimal damage of soft tissue. Furthermore, injured soft tissue was well protected during healing.

[Treatment of calcaneus and mid-foot fractures using closed reposition and fixation with the Ilisarov fixator]

Sixteen fractures of the calcaneus involving the subtalar joint were treated by closed reduction and external fixation using the Ilisarov apparatus. Except for four cases in which temporary arthrodesis of the subtalar or ankle joint was used, fixation was usually only used for the calcaneus. The operative technique is described precisely. Initial follow-up examinations (on average after 1 year) show advantages over conservative treatment, e.g. better anatomical reduction. In addition, early mobilization of the joint and early weight-bearing result in less pain from disuse osteoporosis. Furthermore, several case reports demonstrate the efficiency of this method in tarsal and metatarsal fracture-dislocations.

[In vivo measurements of electric potentials of the Ilisarov external fixator]

Ilisarov's idea that electrical phenomena could contribute to the efficacy of the ring fixation apparatus prompted us to carry out this preliminary investigation. Patients with lower leg fractures and a four-ring fixation apparatus were selected; the electrical potentials were measured over non-fractured and fractured bones. Patients who could not be studied in the Faraday box were subjected to great disturbances, caused by mains voltage and a neighbouring transmitter; in these cases no objective results could be obtained. Only measurements in the Faraday box yielded reproducible results. The results demonstrate that there is generally a difference in electrical potential among the four rings in patients fitted with an Ilisarov apparatus. Furthermore, weight-bearing on the fixator-bone system causes changes in the electrical potential among the rings.

[Initial modifications of the ring fixator apparatus]

To increase the practicability of Ilisarov's ring fixation apparatus, we introduced the following modifications: Clamping of the fixation wires using a quick collet with a force indicator, which enables reproducibly preuse and rapid clamping. Hardened screws to maintain the tension longer. Production of the olive wire from homogeneous implant steel by the cold-press method. Optimization of the cutting edge at the wire tip. Measurement of tension in the fixation wire. A distractor incorporating a clock and a device showing the distraction achieved so that doctor and patient can better supervise the distraction procedure. Simplifications of the wound dressing.

[The arterial blood supply of the tibial and practical consequences]

In the periosteum of the human tibia, the arterial blood supply shows a general sectorial angioarchitecture. There are 4 segments: proximal and distal 1/5, proximal and distal diaphysis. The proximal 1/5 of the tibial periosteum is supplied with blood by the aa. recurrentes tibiales anterior et posterior and the aa. inferiores medialis et lateralis genus. At the proximal diaphysis (next 3/10 of the tibia) periosteal branches arise from the a. tibialis anterior and the a. tibialis posterior. The distal diaphysis (following 3/10 below the middle of the tibia) is nourished exclusively by semicircular rami periostales of the a. tibialis anterior, which move around the bone from both sides and join with each other at the facies medialis. It is the only sector, which is supplied by a single main artery. Concerning the periosteal blood supply of the distal 1/5 of the tibia 2 different types are found. In 2/3 of the cases the lateral side is nourished by a great vessel of the a. fibularis, which is supported by branches arising from the a. tibialis anterior. In 1/3 of the cases this vessel of the a. fibularis is absent and rami periostales of the a. tibialis anterior nourish the lateral aspect of the distal tibia alone. The dorsal region is supplied in all cases by rami of the a. fibularis and a. tibialis posterior. On the medial side the periosteal nourishment is ensured only by anastomoses. Both the facies lateralis and the facies posterior are supplied by direct branches, which arise from the main arteries of the lower leg.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of an angle-stable plate-screw connection and various screw diameters on the stability of plate osteosynthesis. An FE model study]

In a finite element model of a human femur with an attached stainless steel six-hole plate exposed to a load equivalent to that set up by standing on one leg, pressures on the face of the screw holes, bending stresses in the screws, and axial bone stresses in the mid-plate transverse section were determined. The calculations were performed for minor thread diameters of 3 mm, 5 mm and 8 mm. Further calculations were done assuming a fixator-like rigid screw-plate connection. As a model of a fracture a medial bone defect was chosen. The results show a definitive influence of the screw diameter and the screw-plate connection on the load distribution in the system. Increasing screw diameter makes for lower bone stresses combined with increased bending stability, a larger part of the load being carried by the plate. The rigid screw-plate connection (plate fixator) causes less bone stresses, but high bending stresses are set up the points of screw-plate fixation. Maximal stresses for screw and bone are found at the end of the plate, caused by the large difference in the E-module between the steel plate and the bone. End-plate bone and screws are loaded in excess of their material limits when 3 mm core diameters are used, and sometimes when 5 mm core diameters are used, under the assumed conditions. When a medial bone defect reducing the bone cross-sectional area by 44% is present, the loads on the inner screws increase by a factor of 3 and the loads of the distant screws, by a factor of only 1.3. The maximal pressure in the bone cross section increases 4-fold.

Glucocorticoids inhibit prostaglandin synthesis not only at the level of phospholipase A2 but also at the level of cyclo-oxygenase/PGE isomerase

1. Prostanoid synthesis was induced in bone marrow-derived macrophages by addition of exogenous arachidonic acid to the cell cultures. When the cells were preincubated with dexamethasone (10(-7) and 10(-6) M) overnight, prostaglandin synthesis was inhibited by 66.5 +/- 2.8% and 56.7 +/- 2.9% (mean +/- s.d.; n = 3) respectively. 2. Endogenous membrane bound phospholipase A2 was measured with labelled phospholipids used as substrates. The enzyme activity with phosphatidylcholine and phosphatidylethanolamine as substrates was inhibited by 27.0 +/- 8.3% and 23.3 +/- 11.1% (n = 4) respectively, in dexamethasone-treated macrophages compared to control cells. Neither the distribution of radiolabelled arachidonic acid among the different phospholipid species nor the release of arachidonic acid from prelabelled cells were significantly impaired by pretreatment of the macrophages with dexamethasone (1 microM). 3. The enzyme activity of the cyclo-oxygenase/prostaglandin E (PGE) isomerase was measured in cell membranes from control cells and dexamethasone-treated cells. It was inhibited by 40.0 +/- 8.4% (n = 4) in dexamethasone-treated cells as compared to control cells. Thus, glucocorticoids inhibit not only phospholipase A2 in these cells, but predominantly inhibit arachidonic acid metabolism subsequent to its release from phospholipids.

Progress in purification of virus-inactivated factor VIII concentrates. Three generations of solvent/detergent treated plasma derivatives

A production process of a newly developed highly purified and virus-inactivated Factor (F) VIII-concentrate (Octa V.I. and Octavi) is presented. Taking advantage of a selective resin matrix and the solvent/detergent procedure for virus inactivation--known not to denaturate proteins--a product of a specific activity greater than or equal to 100 IU F VIII/mg could be developed in the final container without the use of an immuno-affinity adsorption step. The main steps of the procedure are: Pooled cryoprecipitate is extracted, the extract is cleared from fibrinogen at + 10 degrees C and virus-inactivated at + 28 degrees C after addition of tributyl-phosphate (TNBP) and detergent. Thereafter the extract is brought in contact to a F VIII-selective anion exchange resin using a chromatographic column. TnBP and the detergent are removed by an extensive washing process and the F VIII-activity is concentrated in a fraction, ready for filling, by means of a cascade of wahing- and elution-buffers. The product is free from coagulable protein and gamma-globulins. The F VIIIC: Ag/F VIII:C-ratio is about unity, suggesting the F VIII-molecule remained in its native state. The development of highly purified F VIII concentrate is based on two previous products of lesser purity (spec. activity of about 1 and 10 IU/mg). The evolution is shown by a comparison of detailed analytical data.

[Possibilities and limits of therapy of injuries of the cervical vertebrae with halo fixation]

74 patients were treated with a Halo-thoracic brace in the Department of Traumatology of the AK St. Georg between 1980 and 1986. Of these, 61 had fractures of the cervical spine, nine had tumor-osteolysis, and four had inflammatory destructions of the vertebrae. In almost all cases of fractures of the upper cervical spine (C0-C2) bone healing occurred with applying the Halo fixation alone. In the middle and lower cervical spine, however, secondary operative measures were often necessary because of persistent instabilities, redislocations or neurologic disturbances. New experience in the palliative treatment of malignant osteolysis of the cervical spine shows, that restabilisation of the segments concerned can be achieved by the combined use the Halo apparatus, surgical resection of the involved vertebral bodies with bone grafting and radiotherapy. A new radiolucent Halo apparatus broadens diagnostic and therapeutic facilities.