Real-time 3-D dark-field microscopy for the validation of the cross-linking process of alginate microcapsules

Alginate-based microencapsulation is a promising method for long-term maintenance of cellular and membrane function of the cells and tissue fragments required for in vitro and in vivo biosensors, for tissue engineering and particularly for immunoisolation of non-autologous transplants. Microcapsules of high mechanical strength and optimum permeability can be produced by injection of BaCl2 crystals into alginate droplets before they come into contact with external Ba2+. A key requirement is that the system parameters (number of crystals, speed of the crystal stream etc.) are properly adjusted according to the mannuronic and guluronic acid ratio and the average molecular mass of the alginate as well as to the diameter of the microcapsules. Robust, reliable, rapid and low-cost validation tools are, therefore, needed for assurance of the microcapsule quality. Here, we describe a novel three-dimensional (3-D) dark-field microscopy that allows the real-time measurement of the number and spatial distribution of the injected Ba2+ ions throughout the microcapsules after treatment with sulphate. This novel method requires only a conventional microscope equipped with three polarising filters and a double aperture stop. In contrast to confocal laser scanning microscopy images, peripherally attached BaSO4 precipitates can clearly be distinguished from internal ones. The data also demonstrate that several steps of the alginate gelling process must be improved before such immunoisolation can be used in patients.

Combining high-field EPR with site-directed spin labeling reveals unique information on proteins in action

In the last decade, joint efforts of biologists, chemists and physicists have helped in understanding the dominant factors determining specificity and directionality of transmembrane transfer processes in proteins. In this endeavor, electron paramagnetic resonance (EPR) spectroscopy has played an important role. Characteristic examples of such determining factors are hydrogen-bonding patterns and polarity effects of the microenvironment of protein sites involved in the transfer process. These factors may undergo characteristic changes during the reaction and, thereby, control the efficiency of biological processes, e.g. light-induced electron and proton transfer across photosynthetic membranes or ion-channel formation of bacterial toxins. In case the transfer process does not involve stable or transient paramagnetic species or states, site-directed spin labeling with suitable nitroxide radicals still allows EPR techniques to be used for studying structure and conformational dynamics of the proteins in action. By combining site-directed spin labeling with high-field/high-frequency EPR, unique information on the proteins is revealed, which is complementary to that of X-ray crystallography, solid-state NMR, FRET, fast infrared and optical spectroscopic techniques. The main object of this publication is twofold: (i) to review our recent spin-label high-field EPR work on the bacteriorhodopsin light-driven proton pump from Halobacterium salinarium and the Colicin A ion-channel forming bacterial toxin produced in Escherichia coli, (ii) to report on novel high-field EPR experiments for probing site-specific pK(a) values in protein systems by means of pH-sensitive nitroxide spin labels. Taking advantage of the improved spectral and temporal resolution of high-field EPR at 95 GHz/3.4 T and 360 GHz/12.9 T, as compared to conventional X-band EPR (9.5 GHz/0.34 T), detailed information on the transient intermediates of the proteins in biological action is obtained. These intermediates can be observed and characterized while staying in their working states on biologically relevant timescales. The paper concludes with an outlook of ongoing high-field EPR experiments on site-specific protein mutants in our laboratories at FU Berlin and Osnabrück.

Epidemiologie der Frühsommer-Meningoenzephalitis (FSME) in der Schweiz 1984 bis 2004

Von 1984 bis 2004 wurden in der Schweiz im Rahmen des obligatorischen Meldesystems insgesamt 1370 FSME-Erkrankungen gemeldet, mit einer deutlichen Zunahme in den 90er-Jahren. In den letzten sechs Jahren seit 1999 waren es durchschnittlich 101 Fälle pro Jahr. Dies entspricht einer gesamtschweizerischen Inzidenz von 1,4/105/Jahr oder von ca. 6/105/Jahr bezogen auf die Bevölkerung der betroffenen Regionen. Das männliche Geschlecht war doppelt so häufig betroffen im Vergleich zum weiblichen. Die Altersverteilung zeigte zwei Gipfel im Alter von 6 bis 14 und 60 bis 69 Jahren. Bei unter 6-Jährigen waren Erkrankungen sehr selten (zwei hospitalisierte Kinder pro Jahr). Der Schweregrad der Erkrankungen nahm mit dem Alter zu. Bei 86% der Patienten lag eine neurologische Symptomatik vor, 14% der Patienten wiesen nur grippale Symptome auf. Von den Patienten mit einer neurologischen Symptomatik mussten 90% hospitalisiert werden, 1,3% überlebten die Krankheit nicht (durchschnittlich ein Todesfall pro Jahr seit 1999). Erkrankungen bei vollständig geimpften Personen waren sehr selten. Die meisten Patienten dürften sich an ihrem Wohnort oder in dessen näheren Umgebung infiziert haben, wobei die Inzidenz in den Großstädten gering war (≤ 1/105/Jahr). In kleineren direkt in Endemiegebieten liegenden Städten stieg die Inzidenz bis auf 18/105/Jahr. Im Verlaufe der 21 Jahre haben sich die zu Beginn der 80er-Jahre bekannten Endemiegebiete in vier Kantonen deutlich ausgedehnt und neue Endemiegebiete sind in sieben weiteren Kantonen dazugekommen. Eine häufige Aktivität im Wald gaben 85% der Patienten an. Obwohl es sich dabei in 80% um Freizeitaktivitäten handelte (vor allem Spaziergänge), dürfte die Inzidenz bei den beruflich exponierten Personen immer noch deutlich höher sein. Dies weist darauf hin, dass die Durchimpfung nicht nur bei den Personen, die sich in der Freizeit exponieren, sondern auch bei den beruflich exponierten Personen immer noch zu gering ist, um die Häufigkeit dieser Krankheit und deren Folgen möglichst weitgehend einschränken zu können.

[Polytrauma on the way. Simple measures for efficient life-saving care!]

The General Practitioner (GP) doesn't usually treat polytrauma often. However in Switzerland there are many remote areas where he is first on the scene of the accident. Thus it is important that he knows basic treatment principles in this situation such as the ABC according to the ATLS guidelines. We give a short overview of these important principles.

[Abdominal pain in emergency service--what should I not forget?]

Abdominal pain for the General Practitioner (GP) is an important problem and presents as a significant challenge since the complaint emerges to the primary care provider as one of the 3 most important complaints. This paper serves as a facilitator and guide in helping the General Practitioner differentiate between the so-called normal abdominal pain versus severe abdominal pain which should be referred to a specialist. One of the most important messages the paper attempts to convey is that patients have to be seen and personally examined by the General practitioner. This is a paramount feature in establishing course of severity and outcome. Since approximately 25% of all presenting abdominal pain complaints are unclear, even to the experienced specialist, the authors attempt to direct a focused exam by means of a thorough history and physical examination and then to formulate a decision tree regarding the question of referral or continued primary care by the provider.

Towards a medically approved technology for alginate-based microcapsules allowing long-term immunoisolated transplantation

The concept of encapsulated-cell therapy is very appealing, but in practice a great deal of technology and know-how is needed for the production of long-term functional transplants. Alginate is one of the most promising biomaterials for immunoisolation of allogeneic and xenogeneic cells and tissues (such as Langerhans islets). Although great advances in alginate-based cell encapsulation have been reported, several improvements need to be made before routine clinical applications can be considered. Among these is the production of purified alginates with consistently high transplantation-grade quality. This depends to a great extent on the purity of the input algal source as well as on the development of alginate extraction and purification processes that can be validated. A key engineering challenge in designing immunoisolating alginate-based microcapsules is that of maintaining unimpeded exchange of nutrients, oxygen and therapeutic factors (released by the encapsulated cells), while simultaneously avoiding swelling and subsequent rupture of the microcapsules. This requires the development of efficient, validated and well-documented technology for cross-linking alginates with divalent cations. Clinical applications also require validated technology for long-term cryopreservation of encapsulated cells to maintaining a product inventory in order to meet end-user demands. As shown here these demands could be met by the development of novel, validated technologies for production of transplantation-grade alginate and microcapsule engineering and storage. The advances in alginate-based therapy are demonstrated by transplantation of encapsulated rat and human islet grafts that functioned properly for about 1 year in diabetic mice.

Intracellular delivery of carbohydrates into mammalian cells through swelling-activated pathways

Volume changes of human T-lymphocytes (Jurkat line) exposed to hypotonic carbohydrate-substituted solutions of different composition and osmolality were studied by videomicroscopy. In 200 mOsm media the cells first swelled within 1-2 min and then underwent regulatory volume decrease (RVD) to their original isotonic volume within 10-15 min. RVD also occurred in strongly hypotonic 100 mOsm solutions of di- and trisaccharides (trehalose, sucrose, raffinose). In contrast to oligosaccharide media, 100 mOsm solutions of monomeric carbohydrates (glucose, galactose, inositol and sorbitol) inhibited RVD. The complex volumetric data were analyzed with a membrane transport model that allowed the estimation of the hydraulic conductivity and volume-dependent solute permeabilities. We found that under slightly hypotonic stress (200 mOsm) the cell membrane was impermeable to all carbohydrates studied here. Upon osmolality decrease to 100 mOsm, the membrane permeability to monomeric carbohydrates increased dramatically (apparently due to channel activation caused by extensive cell swelling), whereas oligosaccharide permeability remained very poor. The size-selectivity of the swelling-activated sugar permeation was confirmed by direct chromatographic measurements of intracellular sugars. The results of this study are of interest for biotechnology, where sugars and related compounds are increasingly being used as potential cryo- and lyoprotective agents for preservation of rare and valuable mammalian cells and tissues.

Long-term graft function of adult rat and human islets encapsulated in novel alginate-based microcapsules after transplantation in immunocompetent diabetic mice

We describe the results of the first study to show that adult rat and human islets can be protected against xenogenic rejection in immunocompetent diabetic mice by encapsulating them in a novel alginate-based microcapsule system with no additional permselective membrane. Nonencapsulated islets lost function within 4-8 days after being transplanted into diabetic Balb/c mice, whereas transplanted encapsulated adult rat or human islets resulted in normoglycemia for >7 months. When rat islet grafts were removed 10 and 36 weeks after transplantation, the mice became immediately hyperglycemic, thus demonstrating the efficacy of the encapsulated islets. The explanted capsules showed only a mild cellular reaction on their surface and a viability of >85%, and responded to a glucose stimulus with a 10-fold increase in insulin secretion. Furthermore, transplanted mice showed a slight decrease in the glucose clearance rate in response to intraperitoneal glucose tolerance tests 3-16 weeks after transplantation; after 16 weeks, the rate remained stable. Similar results were obtained for encapsulated human islets. Thus we provide the first evidence of successful transplantation of microencapsulated human islets. In conclusion, we have developed a novel microcapsule system that enables survival and function of adult rat and human islets in immunocompetent mice without immunosuppression for >7 months.

Sports related maxillofacial injuries: the first maxillofacial trauma database in Switzerland

BACKGROUND

With the increase in the amount of medical data handled by emergency units, advances in computerisation have become necessary. New computer technology should have a major influence on accident analysis and prevention and the quality of research in the future.

OBJECTIVES

To investigate the occurrence of sports related maxillofacial injuries using a newly installed relational database. To establish the first sports trauma database in Switzerland.

METHODS

The Qualicare databank was used to prospectively review 57 248 case histories of patients treated in the Department of Emergency Medicine between January 2000 and December 2002. Pre-defined key words were used to collect data on sports related maxillofacial injuries.

RESULTS

A total of 750 patients with maxillofacial injuries were identified. Ninety (12%) were sports related maxillofacial fractures. Most (27%) were sustained during skiing and snowboarding, 22% during team sports such as soccer or ice hockey, and 21% were from cycling accidents. Sixty eight per cent of the cyclists, 50% of the ice hockey players and soccer players, and 48% of the skiers and snowboarders had isolated fractures of the midface. Fractures of the mandible were noted predominantly in contact sports.

CONCLUSIONS

Computerisation of trauma and emergency units and the introduction of customised software can significantly reduce the workload of researchers and doctors. The effective use of new computer technology should have a considerable influence on research and the quality of future prospective and retrospective studies.

Interventional magnetic resonance imaging: an alternative to image guidance with ionising radiation

At present, interventional procedures, such as stent placement, are performed under X-ray image guidance. Unfortunately with X-ray imaging, both patient and interventionalist are exposed to ionising radiation. Furthermore, X-ray imaging is lacking soft tissue contrast and is not capable of true 3-D displays of either interventional device or tissue morphology. Magnetic resonance imaging (MRI) offers excellent soft tissue contrast, 3-D acquisition techniques, as well as rapid image acquisition and reconstruction. Despite these advantages, MR-guided interventions are challenging owing to the limited access to the patient, strong magnetic and radio-frequency fields that require special interventional devices, inferior image frame rates and spatial resolution, and high MRI scanner noise. For MR-guided intravascular interventions, where access to the target organ is achieved through catheters, dedicated hardware and automated image slice positioning techniques have been developed. We illustrate that MR-guided renal embolisations can be performed in closed-bore high-field MR scanners.

Influence of MMR-vaccinations and diseases on atopic sensitization and allergic symptoms in Swiss schoolchildren

The prevalence of asthma and allergic disease has increased in many countries. It has been proposed that vaccinations may contribute to the development of allergic disease by reducing clinical infections in infancy or through the direct IgE-inducing effects of the vaccines. Evidence for a potential role of immunizations in the development of allergic disease is scarce. Therefore the objective was to study the associations between vaccinations against measles, mumps and rubella (MMR), natural infections of these diseases and atopic sensitization to indoor and outdoor allergens and allergic symptoms in schoolchildren. The cross-sectional study including 1537 8(th) grade school children aged 13-15 years living in 10 communities across Switzerland was organized in the framework of an environmental health surveillance program within the School Health Services (Swiss Surveillance Program of Childhood Asthma and Allergies with respect to Air Pollution and Climate, SCARPOL). Main outcome measures were asthma and sneezing during pollen season assessed by parental questionnaires and atopic sensitization determined by IgE concentrations to various allergens. It was found that parents' reported history of measles or mumps was associated with a stronger immune response than two or more vaccinations against the respective infection (measles: geometric mean IgG titers (GMT) lU/ml (95% Cl) 2.8 (2.0-3.9) vs. 1.2 (1.0-1.4), mumps: GMT PE/ml (95% Cl) 16.3 (13.9-19.1) vs. 8.5 (6.1-11.7). With respect to atopic sensitization similar associations for exposure by natural MMR-infections or MMR-vaccinations were found: measles: OR (95% Cl) 1.02 (0.53-1.96) vs. 1.22 (0.69-2.16), mumps: 0.59 (0.38-0.93) vs. 0.79 (0.49-1.27), rubella: 0.93 (0.61-1.43) vs. 0.95 (0.66-1.37), respectively. Inverse relationships were found between the risk of asthma and a positive disease history or vaccination of measles 0.36 (0.14-0.91) vs. 0.45 (0.21-0.98) or a positive serum titer against measles 0.65 (0.35-1.20). From the present study can be concluded that exposure by MMR-vaccinations or natural MMR-infections in childhood does not increase the risk of sensitization to common allergens as well as to allergic respiratory diseases. MMR-vaccinations or natural MMR-infections are therefore an unlikely factor contributing to the increase in atopic disease in developed countries.

Electric-field driven director oscillations in a nematic liquid crystal: A NMR investigation

We have investigated the oscillatory behavior of the nematic director for 4-pentyl-4'-cyanobiphenyl (5CB) when it is subjected to a static magnetic field and a sinusoidal electric field. In these experiments the two fields were inclined at about 50 degrees and the frequency of the electric field was varied from several hertz to approximately 1000 Hz. The director orientation was measured using time-resolved deuterium NMR spectroscopy since this has the advantage of being able to determine the state of director alignment in the sample. In fact, for all of the frequencies studied the director is found to remain uniformly aligned. Since the diamagnetic and dielectric anisotropies are both positive the director oscillates in the plane formed by the two fields. These oscillations were observed to continue for many cycles, indicating that the coherence in the director orientation was not lost during this motion. The maximum and minimum angles made by the director with the magnetic field were determined, as a function of frequency, from the NMR spectrum averaged over many thousand cycles of the oscillations. At low frequencies (several hertz) these limiting angles are essentially independent of frequency but as the frequency increases the two angles approach each other and become equal at high frequencies, typically 1000 Hz. Our results are well explained by a hydrodynamic theory in which the sinusoidal time dependence of the electric field is included in the torque-balance equation. This analysis also shows that, for a range of frequencies between the high and low limits, these NMR experiments can give dynamic as well as static information concerning the nematic phase.

Sensitivity enhancement in pulse EPR distance measurements

Established pulse EPR approaches to the measurement of small dipole-dipole couplings between electron spins rely on constant-time echo experiments to separate relaxational contributions from dipolar time evolution. This requires a compromise between sensitivity and resolution to be made prior to the measurement, so that optimum data are only obtained if the magnitude of the dipole-dipole coupling is known beforehand to a good approximation. Moreover, the whole dipolar evolution function is measured with relatively low sensitivity. These problems are overcome by a variable-time experiment that achieves suppression of the relaxation contribution by reference deconvolution. Theoretical and experimental results show that this approach leads to significant sensitivity improvements for typical systems and experimental conditions. Further sensitivity improvements or, equivalently, an extension of the accessible distance range can be obtained by matrix deuteration or digital long-pass filtering of the time-domain data. Advantages and limitations of the new variable-time experiment are discussed by comparing it to the established analogous constant-time experiment for measurements of end-to-end distances of 5 and 7.5 nm on rod-like shape-persistent biradicals and for the measurement of a broadly distributed transmembrane distance in a doubly spin-labeled mutant of plant light harvesting complex II.

2D TRIPLE in orientationally disordered samples--a means to resolve and determine relative orientation of hyperfine tensors

The two-dimensional (2D) TRIPLE experiment provides correlations between electron-nuclear double resonance (ENDOR) frequencies that belong to the same electron-spin manifold, M(S), and therefore allows to assign ENDOR lines to their specific paramagnetic centers and M(S) manifolds. This, in turn, also provides the relative signs of the hyperfine couplings. So far this experiment has been applied only to single crystals, where the cross-peaks in the 2D spectrum are well resolved with regular shapes. Here we introduce the application of the 2D TRIPLE experiment to orientationally disordered systems, where it can resolve overlapping powder patterns. Moreover, analysis of the shape of the cross-peaks shows that it is highly dependent on the relative orientation of the hyperfine tensors of the two nuclei contributing to this particular peak. This is done initially through a series of simulations and then demonstrated experimentally at a high field (W-band, 95 GHz). The first example concerned the (1)H hyperfine tensors of the stable radical alpha,gamma-bisdiphenylene-beta-phenylallyl (BDPA) immobilized in a polystyrene matrix. Then, the experiment was applied to a more complex system, a frozen solution of Cu(II)-bis(2,2':6',2'' terpyridine) complex. There, the 2D TRIPLE experiment was combined with the variable mixing time (VMT) ENDOR experiment, which determined the absolute sign of the hyperfine couplings involved, and orientation selective ENDOR experiments. Analysis of the three experiments gave the hyperfine tensors of a few coupled protons.

Cross-linking properties of alginate gels determined by using advanced NMR imaging and Cu 2+ as contrast agent

The entrapment of enzymes, drugs, cells or tissue fragments in alginates cross-linked with Ca(2+) or Ba(2+) has great potential in basic research, biotechnology and medicine. The swelling properties and, in turn, the mechanical stability are key factors in designing an optimally cross-linked hydrogel matrix. These parameters depend critically on the cross-linking process and seemingly minor modifications in manufacture have a large impact. Thus, sensitive and non-invasive tools are required to determine the spatial homogeneity and efficacy of the cross-linking process. Here, we show for alginate microcapsules (between 400 microm and 600 microm in diameter) that advanced (1)H NMR imaging, along with paramagnetic Cu(2+) as contrast agent, can be used to validate the cross-linking process. Two- and three-dimensional images and maps of the spin-lattice relaxation time T(1) of Ba(2+) cross-linked microcapsules exposed to external Cu(2+) yielded qualitative as well as quantitative information about the accumulation of Cu(2+) within and removal from microcapsules upon washing with Cu(2+) free saline solution. The use of Cu(2+) (having a slightly higher affinity constant to alginate than Ba(2+)) for gelling gave a complementary insight into the spatial homogeneity of the cross-linking process together with information about the mechanical stability of the microcapsules. The potential of this technique was demonstrated for alginates extracted from two different algal sources and cross-linked either externally by the conventional air-jet dropping method or internally by the "crystal gun" method.

First steps of an interdisciplinary approach towards miniaturised cryopreservation for cellular nanobiotechnology

The only widely used and accepted method for long-term cell preservation is storage below -130 degrees C. The biosciences will make increasing use of preservation and place new demands on it. Currently, cells are frozen in volumes greater than 1 ml but the new cell and implantation therapies (particularly those using stem cells) will require accurately defined freezing and storage conditions for each single cell. Broadly-based, routine freezing of biological samples allows the advantage of retrospective analysis and the possibility of saving genetic rights. For such applications, one billion is a modest estimation for the number of samples. Current cryotechniques cannot handle so many samples in an efficient and economic way, and the need for new cryotechnology is evident. The interdisciplinary approach presented here should lead to a new sample storage and operating strategy that fulfils the needs mentioned above. Fundamental principles of this new kind of smart sample storage are: (i) miniaturisation; (ii) modularisation; (iii) informationsample integration, i.e. freezing memory chips with samples; and (iv) physical and logical access to samples and information without thawing the samples. In contrast to current sample systems, the prototyped family of intelligent cryosubstrates allows the recovery of single wells (parts) of the substrate without thawing the rest of the sample. The development of intelligent cryosubstrates is linked to developments in high throughput freezing, high packing density storage and minimisation of cytotoxic protective agents.

Microscopic origin of the nonexponential dynamics in a glassy crystal

The origin of the slow relaxation and of the dynamic heterogeneity is studied for an orientation-ally disordered crystal, orthocarborane, composed of quasi-icosahedrally shaped molecules. Multidimensional deuteron magnetic resonance reveals that large jump angles dominate their complex, anisotropic reorientational motion. It involves a sequence of small-angle tilts about locally preferred axes as well as symmetry adapted threefold jumps. The intrinsic dynamics of this glassy crystal is nonexponential and can be fully accounted for in terms of the tilt and jump motion.

Beneficial effects of human serum albumin on stability and functionality of alginate microcapsules fabricated in different ways

A key engineering challenge in designing microcapsules made from biocompatible alginate is maintaining adequate exchange of nutrients and oxygen between the entrapped cells and the environment, while simultaneously avoiding swelling and subsequent failure of the microcapsule. Approval for the use of alginate in pharmaceutical and/or biomedical applications also strictly requires that the components of the microcapsule material must meet the safety criteria of the ASTM and FDA. Incorporation of foetal calf serum (FCS) into the microcapsules for stabilization is not in accordance with the guidelines affirmed by these organizations. FCS should be substituted by microcapsule-stabilizing additives that are medically approved. In this communication, it is shown that 10% FCS can be replaced by 1% human serum albumin (i.e. by an agent for which medical approval is granted) without compromising effects on long-term in vitro stability. Furthermore, it is demonstrated that human serum albumin (HSA) significantly enhances cell survival and, particularly, insulin secretion of encapsulated rat islets over a time period of 3 weeks when incubated in culture medium. Thus, HSA-stabilized microcapsules made from UHV(Lam) alginate are apparently a promising system for immunoisolation of cells, particularly when alginate is cross-linked by injection of BaCl(2) crystals into the alginate droplets. Slight adjustments of the alginate concentration can tailor the microcapsule permeability to the released therapeutic factor.

Recent increase in measles in children and teenagers in Switzerland

A total of 387 clinical measles cases have been notified to the Swiss Federal Office of Public Health (SFOPH) in the last two months, a large increase compared to recent years.

Fabrication of homogeneously cross-linked, functional alginate microcapsules validated by NMR-, CLSM- and AFM-imaging

Cross-linked alginate microcapsules of sufficient mechanical strength can immunoisolate cells for the long-term treatment of hormone and other deficiency diseases in human beings. However, gelation of alginate by external Ba(2+) (or other divalent cations) produces non-homogeneous cross-linking of the polymeric mannuronic (M) and guluronic (G) acid chains. The stability of such microcapsules is rather limited. Here, we show that homogeneous cross-linking can be achieved by injecting BaCl(2) crystals into alginate droplets before they come into contact with external BaCl(2). The high effectiveness of this crystal gun method is demonstrated by confocal laser scanning microscopy and by advanced nuclear magnetic resonance imaging. Both techniques gave clear-cut evidence that homogeneous cross-linkage throughout the microcapsule is only obtained with simultaneous internal and external gelation. Atomic force microscopy showed a very smooth surface topography for microcapsules made by the crystal gun method, provided that excess Ba(2+) ions were removed immediately after gelation. In vitro experiments showed greatly suppressed swelling for crystal gun microcapsules. Even alginate extracted from Lessonia nigrescens (highly biocompatible) yielded microcapsules with long-term mechanical stability not hitherto possible. Encapsulation of rat islets, human monoclonal antibodies secreting hybridoma cells and murine mesenchymal stem cells transfected with cDNA encoding for bone morphogenetic protein (BMP-4) revealed that injection of BaCl(2) crystals has no adverse side effects on cell viability and function. However, the release of low-molecular weight factors (such as insulin) may be delayed when using alginate concentrations in the usual range.

Trehalose conserves expression of bullous pemphigoid antigen 180 during desiccation and freezing

Bullous pemphigoid antigen 180 (BP180) is targeted by autoantibodies in a variety of subepidermal blistering skin diseases. We have recently developed a simple, highly specific and sensitive immunofluorescence (IF) assay for the detection of circulating antibodies against BP180. This novel assay involves the expression of full-length (FL) BP180 in Sf21 insect cells that are then examined under IF microscopy after staining with anti-BP180 antibodies. Application of this assay as a routine diagnostic tool requires long-term storage of FL-BP180, which can result in substantial loss of expression. Here, we show that the disaccharide trehalose, a natural cryo- and lyoprotectant, is capable of preserving the FL-BP180 antigen expressed in Sf21 insect cells under various (dry) storage conditions including 40 degrees C, room temperature (RT), 4-8, -20, and -80 degrees C. The protective effect was dose-dependent reaching a maximum at about 200 mM trehalose. Trehalose was superior to other sugars or conventional cryoprotective agents (e.g. sucrose, myo-inositol, DMSO) in preventing greatly reduced antigen expression. Trehalose conserved the expression of both extra- and intracellular epitopes of FL-BP180. Interestingly, protection of the intracellular domain was only observed when trehalose was introduced into the cytosol. Trehalose significantly prolonged the storage time of FL-BP180 expressed in Sf21 insect cells, thus permitting the routine use of the IF assay in clinics for the detection of serum antibodies. The method described here has potential applications for the preservation of other transmembrane proteins.

Paragliding accidents--the spine is at risk. A study from a Swiss Trauma Centre

In recent decades, paragliding-like other fashionable activities-has become a part of lifestyle and outdoor activities. The introduction of protective devices has helped to reduce the risk of severe injuries. However, it seems that the spine remains the paraglider's 'Achilles heel'. Better education, training, and the introduction of innovative back protectors are required to reduce the frequency and severity of paragliding injuries.

Hoof kick injuries in unmounted equestrians. Improving accident analysis and prevention by introducing an accident and emergency based relational database

OBJECTIVE

To assess injury patterns attributable to horse kicks, to raise the issue of preventive measures, and to evaluate the role of modern accident and emergency department computer software.

METHODS

Data analysis using a new kind of full electronic medical record.

RESULTS

Seventeen kicked equestrians were unmounted at the time of injury. Eight of seventeen patients sustained contusions of the extremities, the back, and the trunk. In nine patients an isolated facial injury was diagnosed. Five of nine patients needed referrals to the department of plastic surgery because of the complexity of the facial soft tissue wounds. Three underwent maxillofacial surgery.

CONCLUSION

Clinical: the equestrian community may underestimate the risk of severe injuries attributable to hoof kicks, especially while handling the horse. Educational lectures and the distribution of educational literature should be promoted. The introduction of additional face shields may be protective. Software related issue: the handling of an increasing amount of medical data makes a development in computerisation of emergency units necessary. Thus the increasing utilisation of new computer technology could have a significant influence on accident analysis and prevention and the quality of research in the future.

[Minor craniocerebral trauma]

Mild craniocerebral injury or mild traumatic brain injury (MTBI) predominates, occurring with an 80% frequency. A 1997 publication by the American Academy of Neurology clearly defines MTBI as a transient alteration of mental status, without any neurological deficit, that may or may not involve loss of consciousness or amnesia. On the Glasgow Coma Scale (GCS), mild craniocerebral injury corresponds to a score of 14 and 15. The GCS must be taken immediately. Advanced trauma life support follows primary survey methodology and ABCDE protocol. The prognosis in MTBI is significantly worse when the patient suffers from intercurrent hypotension and hypoxia. In smaller hospitals, 24-hour monitoring is imperative. Wherever computerized tomography (CT) is available, a CT examination is broadly indicated. There is no knowledge of any adverse effects on patients whose GCS worsened when the CT revealed normal findings.

Anisotropic self-diffusion in thermotropic liquid crystals studied by 1H and 2H pulse-field-gradient spin-echo NMR

The molecular self-diffusion coefficients in nematic and smectic-A thermotropic liquid crystals are measured using stimulated-echo-type 2H and 1H pulse-field-gradient spin-echo nuclear magnetic resonance (PGSE NMR) combined with multiple-pulse dipolar decoupling and slice selection. The temperature dependence of the principal components of the diffusion tensor in the nematic phase follows a simple Arrhenius relationship except in the region of nematic-isotropic phase transition where it reflects, merely, the decrease of the molecular orientational order. The average of the principal diffusion coefficients in the isotropic-nematic phase transition region is close to the diffusion coefficient in the isotropic phase. At the nematic-smectic-A phase transition the diffusion coefficients change continuously. The results in nematic phase are best described in terms of the affine transformation model for diffusion in nematics formed by hard ellipsoids. In the smectic-A phase the data are interpreted using a modified model for diffusion in presence of a periodic potential along the director.