Transport properties and ionicity of phosphonium ionic liquids.

Ionic liquids (ILs) are promising electrolytes and many efforts have been made in basic scientific research as well as in applied research. In this contribution, we synthesised a variety of partly novel phosphonium ILs with different anions as well as with different compositions and lengths of the side chains of the cations. We measured a variety of their important transport properties such as viscosity, conductivity and diffusivity by means of stress-controlled rheology, impedance spectroscopy and PFGSTE NMR diffusometry. The results are analysed with respect to different models for derivation from ideal behaviours such as the ionicity and the (fractional) Walden rule depending on their molecular structure. These models are well established in the literature and are herein applied to rarely investigated but promising phosphonium ILs, with a particular emphasis placed on the effect of ether side chains. In comparison, the models show a qualitative correlation but distinct deviation in the quantification especially in the temperature dependent values and with other IL systems. These results aim to facilitate a better understanding of the IL properties depending on the molecular composition and by this way help to choose the ILs with optimal properties for practical applications.

Modification of galactitol dehydrogenase from Rhodobacter sphaeroides D for immobilization on polycrystalline gold surfaces.

Galactitol dehydrogenase (GatDH) from Rhodobacter sphaeroides is a multifunctional enzyme that catalyzes in the presence of oxidized beta-nicotinamide adenine dinucleotide (NAD(+)) the interconversion of various multivalent aliphatic alcohols to the corresponding ketones. The recombinant GatDH was provided with an N-terminal His(6)-tag to which distally up to three cysteine residues were attached. This protein construct maintained nearly full enzymatic activity, and it could be covalently immobilized via thiol bonds onto the surface of a gold electrode. Binding of GatDH onto the gold electrode was verified by SPR measurements, and residual enzyme activity was measured by cyclic voltammetry using 1,2-hexanediol as substrate, the cofactor NAD(+) and the redox mediator CTFM (4-carboxy-2,5,7-trinitrofluorenyliden-malonnitrile) in solute form. The results demonstrate the possibility of a directed functional immobilization of proteins on gold surfaces, which represents a proof-of-concept for the development of reactors for electrochemical synthon preparation using dehydrogenases.

Quasielastic neutron scattering study of hydrogen motion in NbC(0.71)H(0.28).

In order to study the mechanism and parameters of H jump motion in the nonstoichiometric Nb carbides, we have performed quasielastic neutron scattering (QENS) measurements for NbC(0.71)H(0.28) over the temperature range 11- 475 K. Our results indicate that about 30% of H atoms in this system participate in a fast diffusive motion. The temperature dependence of the corresponding H jump rate in the range 298-475 K follows the Arrhenius law with an activation energy of 328 ± 9 meV. The Q dependence of the QENS data suggests that the observed jump motion corresponds to long-range diffusion of H atoms along chains of the off-centre sites in carbon vacancies.

Calorimetric method for the determination of Curie temperatures of magnetic nanoparticles in dispersion.

Mn(x)Zn(1-x)Fe(2)O(4)-based magnetic fluids with x = 0.1-0.9 are synthesized by coprecipitation. The samples are heated in a radio frequency (rf) magnetic field using an rf generator at different powers, and the temperature is measured as function of time using an optical thermometer. The heating effect of the dispersed magnetic nanoparticles is proportional to the imaginary part of the dynamic magnetic susceptibility of the ferrofluid, a quantity that depends on the temperature through the magnetization of the ferrite nanoparticles and the Néel or Brownian relaxation times, respectively. We propose an extrapolation method to actuate the Curie temperatures of the dispersed magnetic nanoparticles. By means of appropriate fitting functions for (dT/dt) versus T for both the heating and the cooling process, we deduce the Curie temperature of the samples under investigation. For Mn(x)Zn(1-x)Fe(2)O(4)-based magnetic nanoparticles the Curie temperatures decrease with increasing Zn content. They turn out to be lower than the literature values for bulk Mn(x)Zn(1-x)Fe(2)O(4), a phenomenon which is generally observed for phase transitions of nanocrystalline materials.

Complete resection of a cavernous haemangioma of the optic nerve, the chiasm, and the optic tract.

The involvement of the optic nerve, the chiasma, and the optic tract by a cavernoma has been reported in only three patients. In all of them, a biopsy of the vascular lesion was obtained. We report a further example of a 38-year-old male patient who suffered from acute onset of severe headache and progressive loss of vision. The vascular malformation of the optic pathways was completely removed via a pterional approach. This is the first reported instance of complete resection of a cavernoma involving the optic nerve, the chiasm, and the optic tract.

Functionalized polymer colloids bearing primary amino groups.

Polymer colloids are prepared via radicalic emulsion polymerisation of butylacrylate. Functionalization with amino groups is achieved by copolymerisation of 2-amino-ethylmethacrylates. In order to over-compensate the positive surface charges resulting from the amino groups additionally vinylbenzenesulfonic acid is copolymerized. The size of the resulting particles is controlled by the molar ratio of amino to sulfonic acid groups. The suitability of amino groups for coupling reactions is demonstrated by electrophilic addition of fluorescein-5-isothiocyanate. The resulting particles are characterized by dynamic light scattering and zeta potential measurements as well as by optical spectroscopy. The suitability of labelled particles for optical tracer experiments is demonstrated by fluorescence correlation spectroscopy.

Electrodeposition of nano- and microcrystalline aluminium in three different air and water stable ionic liquids.

The present work shows, for the first time, a comparative experimental study on the electrodeposition of aluminium in three different water and air stable ionic liquids, namely 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide ([BMP]Tf2N), 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide ([EMIm] Tf2N), and trihexyl-tetradecyl-phosphoniumbis(trifluoromethylsulfonyl)imide (P(14,6,6,6) Tf2N). The ionic liquids [BMP]Tf2N and [EMIm]Tf2N show biphasic behaviour in the AlCl3 concentration range from 1.6 to 2.5 mol L(-1) and 2.5 to 5 mol L(-1), respectively. The biphasic mixtures become monophasic at temperatures >/=80 degrees C. It was found that nanocrystalline aluminium can be electrodeposited in the ionic liquid [BMP]Tf2N saturated with AlCl3. The deposits obtained are generally uniform, dense, shining, and adherent with very fine crystallites in the nanometer size regime. However, coarse cubic-shaped aluminium particles in the micrometer range are obtained in the ionic liquid [EMIm]Tf2N. In this liquid the particle size significantly increases as the temperature rises. A very thin, mirrorlike aluminium film containing very fine crystallites of about 20 nm is obtained in the ionic liquid [trihexyl-tetradecyl-phosphonium]Tf(2)N at room temperature. At 150 degrees C, the average grain size is found to be 35 nm.

Self-diffusion of rodlike and spherical particles in a matrix of charged colloidal spheres: a comparison between fluorescence recovery after photobleaching and fluorescence correlation spectroscopy.

The fluorescence recovery after photobleaching (FRAP) method and the fluorescence correlation spectroscopy (FCS) have been applied on suspensions of highly charged colloidal spheres with a small content of rod-shaped tobacco mosaic virus (TMV) particles. Since these methods only determine the self-diffusion coefficient of the fluorescently labeled species, D(S) of the rods and the spheres could independently be measured. The ionic strength of the dispersion medium has been varied to measure self-diffusion of rods and spheres in dependence on the degree of order of the matrix spheres. In contrast to FRAP, which allows the determination of the long-time self-diffusion coefficient D(S) (L), FCS measures self-diffusion on a shorter time scale. Thus a comparison of the results that were obtained by FCS and FRAP, in combination with Brownian Dynamics simulations, gives insight into the time dependence of the self-diffusion coefficient of an interacting colloidal system. As the mean interparticle distance of the matrix is of the same order of magnitude as the length of a TMV rod, the rotational motion is influenced by the assembly of spheres around a TMV particle. Since FCS is sensitive both to translational and rotational motion, whereas FRAP, which probes the diffusion at much larger length scales, is only sensitive to the translational motion of TMV, the comparison of diffusion coefficients measured employing FRAP and FCS can give some insights in the rotational diffusion: the experimental data indicate a slowing down of the rotational motion of a TMV rod with increasing structural order of the matrix spheres.

Study of clinical features of amyloid angiopathy hemorrhage and hypertensive intracerebral hemorrhage.

OBJECTIVE: The purpose of this study was to differentiate between cerebral amyloid angiopathy (CAA) and hypertension (HTN) based on hemorrhage pattern interpretation. METHODS: From June 1994 to Oct., 2000, 83 patients admitted to our service with acute intracerebral hemorrhage (ICH) were investigated retrospectively; 41 patients with histologically proven diagnosis of cerebral amyloid angiography and 42 patients with clear history of hypertension were investigated. RESULTS: Patients with a CAA-related ICH were significantly older than patients with a HTN-related ICH (74.0 years vs 66.5 years, P < 0.05). There was a significantly higher number of hematomas > or = 30 ml in CAA (85.3%) when compared with HTN (59.5%). No basal ganglional hemorrhage was seen in CAA, but in 40.5% in HTN. In CAA-related ICH, subarachnoid hemorrhage (SAH) was seen in 26 patients (63.4%) compared to only 11 patients (26.2%) in HTN-related ICH. Intraventricular hemorrhage was seen in 24.4% in CAA, and in 26.2% in HTN. Typical features of CAA-related ICH included lobar distribution affecting mainly the lobar superficial areas, lobulated appearance, rupture into the subarachnoid space, and secondary IVH from the lobar hemorrhage. More specifically, multiplicity of hemorrhage, bilaterality, and repeated episodes also strongly suggest the diagnosis of CAA. Multiple hemorrhages, defined as 2 or more separate hematomas in multiple lobes, accounted for 17.1% in CAA-related ICH. CONCLUSION: There are certain features in CAA on CT and MRI and in clinical settings. To some extent, these features may contribute to distinguishing CAA from HTN related ICH.

Metastatic low-grade inflammatory myofibroblastic tumor (IMT) in the central nervous system of a 29-year-old male patient.

A case of myofibrosarcoma (IMT) of the brain and lung as well as the spinal cord is described. A 29-year-old male patient presented with fever (40 degrees C), malaise, vomitus, meningism and leukocytosis. Computer tomography identified a bleeding in the left frontal lobe. A bleeding angioma was suspected and an operation was performed. The histological examination could not reveal an exact diagnosis. Eight months after complete recovery from the first bleeding, the patient had a second intracranial temporo-occipital bleeding on the right side which has been removed operatively. A new lesion was seen in the left parietal white matter of the brain. A growing cavernoma was suspected and resection of the lesion was planned. Pre-operatively the patient suffered from hemoptysis and fever. The X-ray of the chest showed a pulmonary lesion in the left lower lobe. In the CT of the chest a large tumor in the left lower lobe of the lung and additionally a cystic structure in the mediastinum was seen. The histological examination of this tumor identified an inflammatory myofibroblastic tumor (IMT). The left parietal lesion has been resected after the thoracic operation. The brain lesions were estimated to be metastases of the IMT of the lung. In the further clinical history the patient developed a large spinal cord metastasis of the thoracic spine. The metastatic development of the tumor reported in this case is unusual. The current therapy of these tumors consists of complete tumor resection and further clinical controls. However, due to the localization and the extension of some lesions in the present case, the complete resection has not been possible. There is no proven role of chemotherapy and radiation therapy. The patient died due to the pulmonary deterioration.

Outcome and prognostic factors of hemicraniectomy for space occupying cerebral infarction.

OBJECTIVE: To determine long term functional outcome and length of survival of patients undergoing decompressive craniectomy for space occupying infarction of the middle cerebral artery (MCA), and to identify risk factors associated with death and unfavourable outcomes METHODS: Databases of patients undergoing decompressive craniectomy for space occupying MCA infarction compiled at eight neurosurgical departments (1996-2001) were merged, and 188 patients were evaluated. Mortality was calculated by the Kaplan-Meier method. Clinical outcome was rated using the Glasgow outcome scale (GOS). The prognostic impact of patient related covariates on length of survival and the GOS was analysed multivariately. RESULTS: The unadjusted 3, 6, and 12 month mortality rates were 7.9%, 37.6%, and 43.8%, respectively (median follow up, 26 weeks). In the "best" multivariate model, age >50 years (p<0.02) and the involvement of two or more additional vascular territories (p<0.01) had an unfavourable impact on length of survival. The adjusted six month mortality was as low as 20.0% (no risk factor) and as high as 59.7% (two risk factors). A GOS score of 50 years (p<0.0003): 34.9% of the patients 3, as compared with 12.0% of the elderly subpopulation. The side of the infarct did not have prognostic relevance. CONCLUSIONS: Results of surgical treatment in patients <50 years of age undergoing decompressive craniectomy are encouraging. The effectiveness of decompressive craniectomy for patients >50 years remains questionable and should be analysed in the framework of a prospective randomised study.

Subarachnoid hemorrhage of unknown origin and the basilar artery configuration.

It is unclear whether the configuration of the basilar artery (BA) in patients with subarachnoid hemorrhage (SAH) of unknown origin is comparable to that in normal subjects or whether there are differences which may help to identify the origin. We studied the BA configuration in 57 patients with SAH of unknown origin (10%), who were identified in a prospectively collected series of 549 SAH patients consecutively admitted to our service over a 9-year period. There were 30 patients (53%) with non-perimesencephalic SAH and 27 with perimesencephalic SAH (47%). According to a standardized algorithm we determined, on straight anteroposterior digital subtraction angiography (DSA), the width of the proximal BA segment at the origin of the anterior inferior cerebellar artery and the width of the most distal BA segment between the superior cerebellar arteries and the posterior cerebral arteries. Based on these measurements we calculated the distal-proximal BA ratios and compared them to the ratios obtained in a control group of 31 patients who had DSA for reasons other than aneurysmal SAH. The mean ratio in patients with non-perimesencephalic SAH of unknown origin was 1.150 (range: 1.080-1.230). In patients with perimesencephalic SAH of unknown origin it was 1.156 (range: 1.120-1.250). In the control group the mean ratio was 1.163 (range: 1.125-1.200). There are no variations in the configurations of the BA which could possibly explain the cause of this type of SAH or clarify the origin of hemorrhage.

Clinical outcome after surgery of intracranial unruptured aneurysms: results of a series between 1991 and 2001.

The clinical results of surgery for unruptured aneurysms in the Neurosurgical Department of Kiel were analyzed to further discuss whether an operative treatment can be advised. Between 1991 and 2001, 54 unruptured aneurysms in 45 patients were operated in our department. No complications occurred in 38 patients; transient complications (slight aphasia, hemiparesis, psychiatric disorders) in 4 patients; postoperative seizures in one, epidural haematoma with the need of re-operation in one, and infection in another patient. At the time of discharge, GOS was 5 in 33 patients, 4 in 12 patients. But the slight disabilities were due to the aneurysm operation only in two patients, in the other 10 patients they were caused by pre-existing concomitant diseases. The Rankin-Scale after at least 6 months was 1 (no disability) in 31 patients (37 patients investigated); 2 (slight disability) in 5, and 3 (moderate disability) in one patient. In only one of these patients, the slight disability was caused by the aneurysm operation. During a telephone interview performed between 6 months and 7 years after the operation, all patients except two (31 patients investigated) gave a positive answer to the question, whether, in case of diagnosis of an aneurysm, they would undergo an operation again. Regarding our results, we still advocate treatment of unruptured aneurysms in patients who are in stable clinical conditions, especially in young patients and in patients with unique aneurysm configurations and aneurysm sizes approaching 10 mm.

Therapeutical considerations in patients with intracranial venous angiomas.

The clinical presentation of intracranial venous angiomas are usually headache, seizures or dizziness. Very often these anomalies are found incidentally on magnetic resonance imaging (MRI). We reviewed 35 patients, which were examined in our department between 1994 and 2000. Only one patient became symptomatic with an intracranial haematoma, which was removed surgically. In three patients an associated cavernous angioma was found, which was removed successfully with preservation of the coexisting venous angioma. There is no indication in operating a venous angioma because the risk of postoperative deterioration caused by venous infarction is high. When removing cavernous angiomas the associated venous angioma has to be preserved.

Role of potassium channels in the relaxation induced by the nitric oxide (NO) donor DEA/NO in the isolated rat basilar artery.

This study investigates whether potassium ion (K+) channels are involved in the nitric oxide (NO)-induced relaxation in segments of the isolated rat basilar artery, mounted onto a wire myograph. A high extracellular K+ concentration partly inhibited the relaxant effects of the NO donors DEA/NO and SIN-1 (3-morpholino-sydnonimine). Whereas single applications of the K+ channel inhibitors tetraethyl-ammonium (10(-3) M), glibenclamide (10(-6) M), 4-aminopyridine (10(-3) M), or BaCl(2) (5 x 10(-5) M) did not affect the responses to DEA/NO, a combination of these inhibitors reduced the effects of DEA/NO. These data suggest, that the relaxant effects of NO donors are partly mediated via activation of K+channels. Different K+ channel types seem to be involved that function in a redundant manner and compensate for each other.

Stroke pattern interpretation: the variability of hypertensive versus amyloid angiopathy hemorrhage.

INTRODUCTION: It is commonly felt that cerebral amyloid angiopathy (CAA) related intracerebral hemorrhage (ICH) can be distinguished from hypertension (HTN)-related ICH by certain typical features on computerized tomography (CT) and magnetic resonance imaging (MRI). The purpose of this study was to investigate the performance of clinicians who were asked to differentiate between CAA and HTN based on hemorrhage pattern interpretation and to assess the feasibility of such classification. METHODS: The admission scans from 83 patients who were admitted to our service with an acute ICH were presented to 5 clinicians in a randomized and blinded fashion (1 junior, and 1 senior neurosurgical resident, 1 attending neurosurgeon, and 2 neurosurgeon-neuroradiologists). There were no patients who received oral anticoagulants other than low-dose aspirin, or who suffered from vascular malformations or tumors. Scans from 41 patients with a histologically proven diagnosis of CAA and from 42 patients with a clear history of HTN were investigated. Hematoma evacuation was done in all CAA patients and in 59% of HTN patients (n = 25). RESULTS: The overall average classification accuracy was 66.8% (range: 62.7-69.9). For correct HTN classification it was 69.5% (range: 64.3-81), and 63.9% for CAA, respectively (range: 48.9-75.6). There were negligible differences in classification accuracy among all observers. Patients with a CAA-related ICH were significantly older than patients with a HTN-related ICH (74 vs. 66.5 years, p < 0.05). There was a significantly higher number of hematomas >30 ml in CAA (85.3%) when compared with HTN (59.5%). No basal ganglionic hemorrhage was seen in CAA, but in 40.5% in HTN. Intraventricular hemorrhage was seen in 24.4% in CAA, and in 26.2% in HTN. Two patients (4.9%) with CAA, and 7 patients with HTN (16.7%) presented with cerebellar hematomas. CONCLUSIONS: Three of 10 scans were not correctly diagnosed regardless of the examiner's level of training. This calls into question the reliability of classifying the underlying pathological condition based on hemorrhage pattern interpretation on CT or MRI. The definite diagnosis of CAA- versus HTN-related hemorrhage requires a histopathological confirmation and should not be based solely on hemorrhage pattern interpretation.

Granular-cell tumour: a rare suprasellar mass.

Granular-cell tumour is a rare suprasellar space occupying lesion, which usually presents with visual deterioration, endocrine deficits or headache. We present two women with extraordinarily large tumours, measuring 3.8 and 4.0 cm in diameter. In both cases the tough, vascular tumour could be removed only subtotally.

Effects of potassium channel inhibitors on the relaxation induced by the nitric oxide donor diethylamine nitric oxide in isolated human cerebral arteries.

OBJECT: The goal of this study was to investigate whether K+ channels are involved in nitric oxide (NO)-induced relaxation of isolated human cerebral arteries. METHODS: Successive concentration-response curves relating to the use of the NO donor diethylamine NO (DEA/NO) were established in the absence and presence of different K+ channel inhibitors after mounting human cerebral arteries onto a wire myograph. The arteries were obtained from macroscopically intact tissue that had been removed during brain tumor operations. A high K+ concentration partially inhibited the relaxant effects of DEA/NO. Different K+ channel inhibitors (tetraethylammonium [TEA], 10(-3) M; charybdotoxin, 10(-7) M; glibenclamide, 10(-6) M; 4-aminopyridine [4-AP], 10(-3) M; BaCl2, 5 x 10(-5) M; and apamin, 10(-6) M) alone failed to affect the responses to DEA/NO. However, a combination of TEA, glibenclamide, 4-AP, and BaCl2 partially blocked the relaxant effects of DEA/NO. In addition, the effects of DEA/NO were inhibited by the thromboxane A2 analog U46619 (3 x 10(-7) M). CONCLUSIONS: Inhibitors of the large-conductance or small-conductance Ca++-activated K+ channels, the adenosine triphosphate-sensitive K+ channels, and the delayed-rectifier or inward-rectifier K+ channels failed to alter the effects of DEA/NO when only one K+ channel blocker was used. However, a regimen of a combination of K+ channel blockers that possess selectivity for different channels demonstrated that different K+ channel types are involved; these channels may function in a redundant manner and compensate for each other. Selective thromboxane A2 agonists are capable of inhibiting the relaxant response to the NO donor.

[Neuronavigation in the region of the skull base]. / Neuronavigation im Bereich der Schädelbasis.

Neuronavigation (computer-aided surgery planning and performance) has proven to be helpful in performing neurosurgical operations. The experiences of our department gained on more than 500 patients operated upon will be presented, with special focus on more than 100 operations for lesions on the skull base. Navigation is one of several modern surgical tools, its value cannot be defined without observing other improvements e.g. in the area of preoperative diagnostics, intraoperative monitoring, microsurgical instruments and microsurgical approaches.

Threshold concentrations of endothelin-1: the effects on contractions induced by 5-hydroxytryptamine in isolated rat cerebral and mesenteric arteries.

This study compares the effects of threshold concentrations of endothelin-1 in isolated rat basilar arteries with those in mesenteric arterial branches and investigates the mechanisms of inhibitory and potentiating endothelin-1-effects. In basilar arteries, endothelin-1 reduces the contractions induced by 5-hydroxytryptamine (5-HT), by the thromboxane A2 agonist U46619, and by vasopressin. The inhibitory effect of endothelin-1 on the contraction induced by 5-HT is abolished by deendothelialization, by the endothelin ET(B) receptor antagonist RES 701-1, by indomethacin, or by glibenclamide. In mesenteric arteries, endothelin-1 potentiates the contractile effects of 5-HT, U46619, and vasopressin. The potentiation of the contractile effect induced by 5-HT is only somewhat modified by deendothelialization, but abolished by the thromboxane A2 receptor antagonists GR32191 and ridogrel. U46619 potentiates the 5-HT-effect in mesenteric arteries. Thus, though the contractile endothelin ET(A) receptors were not blocked, threshold concentrations of endothelin-1 inhibited contractile effects in the rat basilar artery via activation of endothelial ET(B) receptors. Prostaglandins and ATP-sensitive K+ channels are involved in this inhibitory action. In contrast, endothelin-1 potentiates contractile actions in mesenteric arteries via the release of endogeneous thromboxane A2 from non-endothelial cells. The study points out the completely different role of the endothelium in combined effects of endothelin-1 between cerebral and mesenteric arteries.