[Which factors are predictive for long-term complaints after mild traumatic brain injuries?]. / Lassen sich Langzeitfolgen eines leichten Schädelhirntraumas anhand von Labor- und bildgebender Diagnostik vorhersagen?

Each year 330 of every 100,000 inhabitants in Germany suffer a mild traumatic brain injury. About 25% suffer persisting post-concussion syndrome (headache, dizziness). Although many studies have been carried out to make a prognosis of the long-term outcome of these patients, there are still no relevant tests for a valuable statement. The aim of our study was to identify parameters to predict post-traumatic complaints. Therefore we conducted a prospective study of 74 patients who were admitted with a mild traumatic brain injury in our hospital from March 2004 till October 2006. We were able to show a significant correlation between complaints and a pathological CT-scan and biochemical markers during the first two weeks. For long-term complaints only the SKT (Syndromkurztest) we used for a neuropsychological assesment was able to show a significant correlation.

Industrial carbohydrate biotransformations.

Nearly all major industrial processes which involve carbohydrates, include biotechnological transformations. This is due to the complex nature of carbohydrates where stereo- and regioselectivity are highly complex and difficult to control. Enzymes and microorganisms work highly selectively and efficiently in water solution, and provide high yield in general. The article focuses on different types of reactions, including large-scale processes. Topics are hydrolytic reactions, including starch processing, oxidation and reduction transformations including organic acids, such as gluconic and ketogluconic acids and vitamin C synthesis, and isomerization and transfer reactions, which are established on a very large scale to produce glucose/fructose syrups and sucrose isomers. The article will further discuss some mechanistic aspects which are relevant for technology and present selected details of industrial-scale processing. Finally an outlook outlines perspectives of future processes.

Salt-sensitive men show reduced heart rate variability, lower norepinephrine and enhanced cortisol during mental stress.

Salt sensitivity (SS) represents a risk factor for essential hypertension, which has been related to enhanced cardiovascular stress reactivity possibly mediated by increased noradrenergic susceptibility. We investigated biophysiological responses to mental stress in salt-sensitive (ss) and salt-resistant (sr) subjects, hypothesizing lower heart rate variability (HRV) and higher cortisol in the ss. A total of 48 healthy normotensive Caucasian men (age 25.6+/-2.6, body mass index 22.9+/-2.3) were phenotyped for SS (defined as significant drop in mean arterial pressure>3 mm Hg under the low-salt diet) by a 2-week high- versus low-salt diet. Subjects underwent a standardized mental stress task with continuous cardiovascular monitoring before, during and after the test (Finapres; Ohmeda, Louisville, CO, USA). Blood samples were drawn to examine cortisol and catecholamines before, after and 20 min after stress. The task elicited significant increases of systolic blood pressure (SBP), diastolic BP (DBP) and heart rate (HR) and a significant decrease of HRV (all time effects P<0.0001). The ss subjects showed lower norepinephrine (NE) and higher cortisol, indicated by significant group effects (P=0.009 and 0.025, respectively). HR increased and HRV decreased more in the ss under the stress, shown by significant time by group interactions (P=0.045 and 0.003, respectively). The observation of a more pronounced HR rise coupled with a greater decrease of HRV in healthy ss men under the influence of brief mental stress confirms their enhanced physiological stress reactivity. The lower peripheral NE may represent an effort to compensate for increased noradrenergic receptor sensitivity. The enhanced cortisol levels are backed by recent genetic findings on HSD11B2 polymorphisms and may promote hypertension.

Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation.

We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.

Image transfer by mobile phones in neurosurgery.

Image transfer by mobile phones with built-in cameras (1 Megapixel CCD digital camera, 7 stage digital zoom, max. picture size 858 x 1 144 pixels, display resolution 240 x 320 dots, 262 K colour system CGS LCD) was introduced into clinical practice in the author's department in July 2004 to improve communication between neurosurgeons. During the first 12 months of use 13-72 images per month with an average of 1.4 images/case were transmitted via the regular German mobile phone net (GRPS standard, 40 KBit/s) among all neurosurgeons. Most images were transferred from the resident on call to the senior neurosurgeon backing him up. Overall, the system was extremely reliable, quick, and enabled immediate decisions in all emergency situations. In conclusion, image transfer by mobile phones has significantly improved communication within our department.

Investigations of the transfructosylation reaction by fructosyltransferase from B. subtilis NCIMB 11871 for the synthesis of the sucrose analogue galactosyl-fructoside.

The exo-fructosyltransferase produced from B. subtilis NCIMB 11871 strain transfers the fructose moiety from donor alpha12 linked saccharides such as sucrose, raffinose and stachyose to the acceptor d-galactose, leading to the sucrose analogue, galactosyl-fructoside. Here, we report detailed kinetic studies. The enzyme showed a remarkably high optimal temperature at 50 degrees C and was effectively immobilised on Eupergit C 250 L and Trisopor-Amino. This is also the first report about the equilibrium of the transfructosylation reaction, its activation energy determination, the structure of the product and its preparative scale isolation.

Design of immobilised dextransucrase for fluidised bed application.

Immobilisation of dextransucrase from Leuconostoc mesenteroides NRRL B-512F in alginate is optimised for applications in a fluidised bed reactor with high concentrated sugar solutions, in order to allow a continuous formation of defined oligosaccharides as prebiotic isomalto-oligosaccharides. Efficient design of fluidised bed immobilised biocatalyst in high density solutions requires particles with elevated density, high effectiveness and both thermal and mechanical stability. Inert silica flour/sand (Mikrosil 300) as supplement turned out to be best suited for increasing the density up to 1400 kg m(-3) of the alginate beads and generating a stable expanded bed without diffusional restrictions. Kinetic investigations demonstrate that low effectiveness of immobilised enzyme due to close association to dextranpolymers (dextran content of enzyme preparation >90%) is compensated by reducing the particle size and/or by decreasing the dextran content. A low dextran content (5%) is sufficient to immobilise and stabilise the enzyme, thus diffusional limitation is reduced essentially while operational stability is maintained. Fluidisation behaviour and bed expansion proved to be appropriate for the intended application. Both calculated and measured expansion coefficients showed good agreement for different conditions.

Cloning of the pelA gene from Bacillus licheniformis 14A and biochemical characterization of recombinant, thermostable, high-alkaline pectate lyase.

The pectate lyase gene pelA from alkaliphilic Bacillus licheniformis strain 14A was cloned and sequenced. The nucleotide sequence corresponded to an open reading frame of 1,026 bp that codes for a 39 amino acid signal peptide and a mature protein with a molecular mass of 33,451 Da. The mature PelA showed significant homology to other pectate lyases belonging to polysaccharide lyase family 1, such as enzymes from different Bacillus spp. and Erwinia chrysanthemi. The pelA gene was expressed in Escherichia coli as a recombinant fusion protein containing a C-terminal His-tag, allowing purification to near homogeneity in a one-step procedure. The values for the kinetic parameters K(m) and Vmax of the fusion protein were 0.56 g/l and 51 micromol/min, respectively. The activity of purified PelAHis was inhibited in the presence of excess substrate. Characterization of product formation revealed unsaturated trigalacturonate as the main product. The yields of unsaturated trigalacturonic acids were further examined for the substrates polygalacturonic acid, citrus pectin and sugar-beet pectin.

Fluidized bed adsorption of cephalosporin C.

Fluidized bed adsorption can substantially simplify the recovery of products from fermentation. There are, however, several critical parameters, which have a significant influence on the performance of such systems. This paper presents experimental results on the adsorption of an antibiotic, Cephalosporin C, on macroporous adsorbents of the polystyrene type and on an ion exchanger. Internals (static mixers) were used to control bed expansion and mixing, the range of flow rates could thus be extended significantly. An integrated mathematical model was developed comprising bed expansion, residence time distribution and mixing, adsorption kinetics and equilibria.

Enhanced affective startle modulation in salt-sensitive subjects.

Salt-sensitive normotensive men exhibit an enhanced pressor response to mental stress. Although an enhanced pressor response is associated with higher affective startle modulation in men, an association between salt sensitivity of blood pressure and affective startle modulation has not been studied so far. We studied reactivity to mental stress and startle modulation in 14 salt-sensitive healthy white male students and 14 salt-resistant control subjects, who were well matched for age, body mass index, physical fitness, and family history of hypertension. Subjects performed a computerized information-processing task under time pressure (manometer test), while heart rate and blood pressure were continuously registered. In a separate session, subjects viewed a series of 42 pictures of the International Affective Picture System (IAPS), varying in pleasure and arousal, while acoustic startle probes were administered randomly, and electromyogram activity of the orbicular eye muscle was continuously recorded. Startle modulation was calculated as the difference between startle responses under negative and positive affective stimuli. In contrast to salt-resistant subjects, salt-sensitive subjects showed significantly enhanced startle amplitudes under negative stimuli and diminished amplitudes under positive stimuli. Thus, salt-sensitive subjects displayed a significantly higher startle modulation than did salt-resistant subjects (P<0.05). Subjective ratings of the presented IAPS pictures did not differ between the groups. The increased startle modulation of salt-sensitive subjects suggests an enhanced activity of the central nucleus of the amygdala. This enhanced central nervous responsiveness may contribute to higher sympathetic pressor reactivity and, thus, to the later development of hypertension in salt-sensitive individuals.

Claudin-1, claudin-2 and claudin-11 are present in tight junctions of choroid plexus epithelium of the mouse.

The choroid plexus epithelium forms the blood-cerebrospinal fluid (CSF) barrier and is responsible for the secretion of the CSF from the blood. The morphological correlate of the blood-CSF barrier are the tight junctions of choroid plexus epithelium. By freeze-fracture electron microscopy it has been demonstrated that choroid plexus epithelial tight junctions form parallel strands resembling those of Sertoli cells building the blood-testis barrier and those of the myelin sheaths of oligodendrocytes. As the oligodendrocyte specific protein/claudin-11 has been shown to be the central mediator of parallel-array tight junctions in Sertoli cells and myelin sheaths in mice, we asked whether claudin-11 is present in the tight junctions of choroid plexus epithelial cells of the mouse. Here, we present the first direct evidence that claudin-11 besides claudin-1 and -2, occludin and the zonula occludens protein ZO-1 is present in choroid plexus epithelial tight junctions. During inflammation in the central nervous system such as experimental autoimmune encephalomyelitis, the molecular composition of choroid plexus epithelial tight junctions does not change considerably. Their unique molecular composition, with claudin-11 accompanied by claudin-1 and claudin-2 points to a unique regulatory mechanism of the blood-CSF-barrier function.

Salt-sensitivity and other predictors of stress-related cardiovascular reactivity in healthy young males.

Individuals whose mean arterial blood pressure is depending on oral salt intake are considered salt-sensitive and are at risk of developing essential hypertension. This study investigates the role of salt-sensitivity with respect to systolic blood pressure reactions under standardized mental stress. Forty-three healthy young males, previously characterized as salt-sensitive (n=16) or salt-resistant (n=27) by a dietary regimen, were subjected to multimodal physiological measurement during a computerized stress test and underwent comprehensive psychometrical testing. The most important predictors for systolic blood pressure reactions to stress were the degree of salt-sensitivity, body mass index and psychological characteristics like anxiety. The highest correlations with the degree of salt-sensitivity were found for the parameters age, systolic blood pressure reaction under stress, high frequency band of heart rate variability and two psychological variables. The concept of salt-sensitivity is a novel biological component that might contribute to reactivity research in subjects at high risk for essential hypertension.

Involvement of the choroid plexus in central nervous system inflammation.

During inflammatory conditions in the central nervous system (CNS), immune cells immigrate into the CNS and can be detected in the CNS parenchyma and in the cerebrospinal fluid (CSF). The most comprehensively investigated model for CNS inflammation is experimental autoimmune encephalomyelitis (EAE), which is considered the prototype model for the human disease multiple sclerosis (MS). In EAE autoagressive CD4(+), T cells gain access to the CNS and initiate the molecular and cellular events leading to edema, inflammation, and demyelination in the CNS. The endothelial blood-brain barrier (BBB) has been considered the obvious place of entry for the circulating immune cells into the CNS. A role of the choroid plexus in the pathogenesis of EAE or MS, i.e., as an alternative entry site for circulating lymphocytes directly into the CSF, has not been seriously considered before. However, during EAE, we observed massive ultrastructural changes within the choroid plexus, which are different from changes observed during hypoxia. Using immunohistochemistry and in situ hybridization, we observed expression of VCAM-1 and ICAM-1 in the choroid plexus and demonstrated their upregulation and also de novo expression of MAdCAM-1 during EAE. Ultrastructural studies revealed polar localization of ICAM-1, VCAM-1, and MAdCAM-1 on the apical surface of choroid plexus epithelial cells and their complete absence on the fenestrated endothelial cells within the choroid plexus parenchyme. Furthermore, ICAM-1, VCAM-1, and MAdCAM-1 expressed in choroid plexus epithelium mediated binding of lymphocytes via their known ligands. In vitro, choroid plexus epithelial cells can be induced to express ICAM-1, VCAM-1, MAdCAM-1, and, additionally, MHC class I and II molecules on their surface. Taken together, our observations imply a previously unappreciated function of the choroid plexus in the immunosurveillance of the CNS.

[Emotional irritability and anxiety in salt-sensitive persons at risk for essential hypertension]. / Salzsensitive Risikopersonen für die Entwicklung einer essentiellen Hypertonie sind emotional gereizt und ängstlich.

Personality traits such as anxiety and anger have long been associated with essential hypertension. However, the results of past studies have been criticised for selection bias, and it has not been clarified whether psychological traits are causes or consequences of high blood pressure. We studied emotional state and trait patterns and reactivity to mental stress in 16 healthy salt-sensitive volunteers at genetic risk of developing hypertension, and a well-matched control group. We have previously reported increased blood pressure reactivity to mental stress in those individuals. In this paper, we present the results of several standardized psychological questionnaires in which salt-sensitive individuals displayed increased anxiety (p < 0.01), emotional irritation (p < 0.01) and a lower level of anger control (p < 0.01). Thus, an elevated level of anxiety and irritation, as well as an increased blood-pressure response to mental stress may play a role in the development of salt-sensitive hypertension.

Modelling of oligosaccharide synthesis by dextransucrase.

Dextransucrase catalyses the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. Much experimental work has been carried out and a scheme of reactions and a mathematical model have been developed to describe the complex kinetic behaviour of the enzyme. A computer program was used to calculate the parameters of the model from a broad range of experimental data, investigating a large number of kinetic tests with the acceptors maltose and fructose. The results lead to design considerations for a continuous reactor system with immobilized dextransucrase to produce leucrose, a disaccharide of industrial interest.

Kinetic modeling of oligosaccharide synthesis catalyzed by leuconostoc mesenteroides NRRL B-1299 dextransucrase

The kinetic behavior of soluble and insoluble forms of dextransucrase from Leuconostoc mesenteroides NRRL B-1299 was investigated with sucrose as substrate and maltose as acceptor. To study the parameters involved, a kinetic model was applied that was previously developed for L. mesenteroides NRRL B-512F dextransucrase. There are significant correlations between the parameters of the soluble form of B-1299 dextransucrase and those calculated for the B-512F enzyme; that is, their properties are comparable and differ from those of the insoluble form of B-1299 dextransucrase. Whereas the calculated parameters for high maltose concentrations describe the kinetic behavior very well, the time curves for low maltose concentrations were not described correctly. Therefore, the parameters were calculated separately for the two ranges. Copyright 1999 John Wiley & Sons, Inc.

Nonselective nerve fibre damage in peripheral nerves after experimental thermocoagulation.

In this study the morphological effects of local heat application by controlled thermocoagulation to the sciatic nerve of rabbits are investigated. It concentrates on the question of a possible selective elimination of nerve fibres depending on their calibers. Temperatures of 50 degrees C, 55 degrees C, 60 degrees C, 70 degrees C and 90 degrees C were applied for 45 seconds. The nerves were examined histologically after 2-3 minutes, 7 and 12 days and 5 weeks. The light and electronmicrographs show no differential vulnerability of small myelinated or unmyelinated fibres as proposed by Sweet and Wepsic [20]. At a temperature of 50 degrees C no fibre is damaged whereas at 60 degrees C the fibre damage extends over nearly the total cut surface of the nerve. Even at the critical temperature of 55 degrees C affecting only part of the cross-section no predilection of any fibre caliber was observed. In summary thermocoagulation seems not to be able to cause selective fibre damage.