Oleofoams: Properties of Crystal-Coated Bubbles from Whipped Oleogels-Evidence for Pickering Stabilization.

Interfacially stabilized nonaqueous lipid-based foams, which we name here oleofoams, are rarely encountered as opposed to the large number of aqueous foams stabilized by molecular or particulate emulsifiers. There is no case well described in the literature with a convincing characterization of the interfacial contribution to oleofoam stability. Methods for filling this gap are described here, which reach out to a large part of the lipid phase diagram. We bring here complete evidence that lipidic crystals made of a high fraction of fully soluble monoglyceride (MG) in oil do not only adsorb at the oil-air interface but also can easily form a jammed, closely packed layer of crystals around the bubbles of a foam produced by whipping (Pickering effect). Very fine bubbles, soft textures, or firmer ones such as for shaving foams could be obtained, with a high air fraction (up to 75%), which is unprecedented. A thin, jammed layer of crystals on bubbles can cause bubbles to retain nonspherical shapes in the absence of bulk effects for times much longer than the characteristic capillary relaxation time for bare bubbles, which is actual evidence for Pickering-type interfacial stabilization. By comparing to foams obtained by depressurization, we show that whipping is necessary for bubble wrapping with a layer of crystals. The origin of high stability against Ostwald ripening at long times is also discussed. Furthermore, we show that these Pickering whipped foams have rheological properties dominated by interfacial or film contributions, which is of high interest for food and cosmetics applications because of their high moduli. This system can be considered to be a model of the crystallization behavior of MG in oil, which is similar to that in many fats. Our methods are very general in the context of lipid-based foaming, in particular, from food materials, and were used in patent applications.

Nephron sparing surgery in von Hippel-Lindau associated renal cell carcinoma; clinicopathological long-term follow-up.

We evaluated the clinicopathological outcome of von Hippel-Lindau (VHL)-patients who had mainly undergone nephron sparing surgery (NSS) for renal cell carcinoma (RCC) when the tumour diameter has reached 4.0 cm. Multiple, bilateral RCC with high recurrence rates and subsequent repeated interventions, followed by increasing risk for end-stage renal failure and metastases is characteristic for VHL. NSS is widely used for VHL-associated RCC at 3.0 cm cut-off. 54 VHL patients underwent NSS, nephrectomy or thermal ablation for RCC. We analysed time to second treatment, overall and cancer specific survival, intra- and post-operative data as well as tumour characteristics. We also examined the effects of delaying removal of RCC to 4.0 cm cut-off. Median follow-up was 67 months. 54 patients underwent 97 kidney treatments. 96 % of first and 67 % of second interventions comprised of NSS. 0 % metastases were observed in the group with largest tumour size ≤4 cm. The probability for second surgery was 21 %, at 5 years and 42 % at 10 years. Median time to second NSS was 149.6 months. The overall and cancer specific survival rate was 96.5 and 100 % at 5-year follow-up, and 82.5 and 90.5 % respectively at 10-year follow-up. Median delay to second NSS at 4.0 cm cut-off versus 3.0 cm was 27.8 months. NSS was both successfully used in first and second surgery and to some extent even in third surgery. By following a strict surveillance protocol it is possible to support a 4.0 cm-threshold strategy for NSS, based on the assumption that delaying time to second NSS prevents patients from premature renal failure.

Growth kinetics in von Hippel-Lindau-associated renal cell carcinoma.

OBJECTIVE: To evaluate the growth kinetics of renal cell carcinoma (RCC) in von Hippel-Lindau (VHL) disease in a large trial by CT/MRI scan. VHL disease is a multisystemic disorder predisposing to renal cysts and cancer. There is a general assumption that VHL-associated RCC presents slower growth rates than sporadic RCC. PATIENTS AND METHODS: We describe growth kinetics of 96 renal tumours in 64 VHL patients with analysed germline mutation (54/64 treated, 10/64 active surveillance) over a mean follow-up of 54.9 months. We calculated tumour volume, growth rate, multiplication of tumour volume per year and overall, as well as tumour volume doubling time. RESULTS: The mean growth rate of 96 tumours was 4.4 mm/year (SD 3.2, median 4.1 mm/year), mean volume doubling time was 25.7 months (SD 20.2, median 22.2 months). We saw a median 1.4-fold increase in tumour volume per year. At treatment time point, VHL kidneys comprised 39% tumour and 15.7% cyst volume fraction. We saw no correlation between tumour size and growth parameters. CONCLUSION: VHL-associated RCC show large variances in tumour growth behaviour. Compared to the literature, in our study the growth rates (mm/year) of RCC in VHL disease did not differ from those of sporadic RCC. Fast tumour growth increases the risk for metastases.

Rock salt-urea-water (1/1/1) at 293 and 117 K.

The crystal structure of NaCl.CH(4)N(2)O.H(2)O has been determined at 117 K and redetermined at room temperature. It can be described as consisting of alternating ;organic' and ;inorganic' planar layers. While at room temperature the structure belongs to the space group I2, the low-temperature structure belongs to the space group Pn2(1)m. All water O atoms are located on positions with crystallographic symmetry 2 (m) in the room-temperature (low-temperature) structure, which means that the water molecules belong, in both cases, to point group mm2. During the phase transition, half of the urea molecules per unit cell perform a 90 degrees rotation about their respective C-O axes. The other half and the inorganic parts of the structure remain unaltered. The relationship between the two phases is remarkable, inasmuch as no obvious reason for the transition to occur could be found; the internal structures of all components of the two phases remain unaltered and even the interactions between the different parts seem to be the same before and after the transition (at least when looked at from an energetic point of view).

[A method for reassessment of cost-intensive cases in visceral surgery. Results of project by the German Society for Visceral Surgery]. / Methode zur Abbildung kostenintensiver Fälle in der Viszeralchirurgie. Ergebnisse des DRG-Projekts der Deutschen Gesellschaft für Viszeralchirurgie.

Since the introduction of diagnosis-related groups (DRGs) many surgical departments report inappropriate reimbursement for complex cases and a shift in costly cases. To evaluate this situation, the German Society for Visceral Surgery inaugurated the present cost calculation project. In three university hospitals for 50 cases each, we depicted possible cost separators and utilized the complete cost calculation data (so-called Paragraph 21 data set) to test these separators. We identified "admission from another hospital", "severe surgically relevant concomitant disease", and "reoperation during the same hospital admission". The last was considered the economically most significant and medically most valid factor and was submitted as a possible modification to the german DRG system. The proposed cost separator "reoperation during the same hospital admission" was introduced into the DRG system after validation and leads to better allocation of reimbursements to complex and costly cases.

[Von Hippel-Lindau disease. Interdisciplinary patient care]. / Von-Hippel-Lindau-Erkrankung. Interdisziplinäre Patientenversorgung.

Von Hippel-Lindau disease is an important hereditary tumor syndrome with a clear option for effective treatment if diagnosed in time. Interdisciplinary cooperation is the key to successful management. Major components of the disease are retinal capillary hemangioblastomas, hemangioblastomas of cerebellum, brain stem and spine, renal clear cell carcinomas, pheochromocytomas, multiple pancreatic cysts and islet cell carcinomas, tumors of the endolymphatic sac of the inner ear, and cystadenomas of the epididymis and broad ligament. A well structured screening program should be performed at yearly intervals.

Artifact reduction in moving-table acquisitions using parallel imaging and multiple averages.

Two-dimensional (2D) axial continuously-moving-table imaging has to deal with artifacts due to gradient nonlinearity and breathing motion, and has to provide the highest scan efficiency. Parallel imaging techniques (e.g., generalized autocalibrating partially parallel acquisition GRAPPA)) are used to reduce such artifacts and avoid ghosting artifacts. The latter occur in T(2)-weighted multi-spin-echo (SE) acquisitions that omit an additional excitation prior to imaging scans for presaturation purposes. Multiple images are reconstructed from subdivisions of a fully sampled k-space data set, each of which is acquired in a single SE train. These images are then averaged. GRAPPA coil weights are estimated without additional measurements. Compared to conventional image reconstruction, inconsistencies between different subsets of k-space induce less artifacts when each k-space part is reconstructed separately and the multiple images are averaged afterwards. These inconsistencies may lead to inaccurate GRAPPA coil weights using the proposed intrinsic GRAPPA calibration. It is shown that aliasing artifacts in single images are canceled out after averaging. Phantom and in vivo studies demonstrate the benefit of the proposed reconstruction scheme for free-breathing axial continuously-moving-table imaging using fast multi-SE sequences.

Whole-body MRI in comparison to skeletal scintigraphy in detection of skeletal metastases in patients with solid tumors.

AIM: To evaluate the diagnostic value of whole-body magnetic resonance imaging (MRI) and skeletal scintigraphy in the detection of skeletal metastases in patients with solid tumors. MATERIALS AND METHODS: One hundred and twenty-nine tumor patients were examined with whole-body MRI using coronal TIRM sequences for the different anatomical regions. Skeletal scintigraphy was performed with 99mTc-DPD. RESULTS: In 105/129 (81%) patients, the whole-body MRI and skeletal scintigraphy findings were concordant. In 56/129 (43%) patients, both imaging modalities excluded skeletal metastases. In 49/129 (38%) patients, whole-body MRI and skeletal scintigraphy revealed metastases, however whole-body MRI demonstrated more extensive disease in 22/49 (45%) cases. In 6/49 (12%) cases, skeletal scintigraphy was superior to whole-body MRI in detecting more skeletal metastases. In 24/129 (19%) cases, the imaging findings were discordant. In 15 cases, skeletal scintigraphy was negative, whereas whole-body MRI revealed skeletal metastases. In 9 cases, skeletal scintigraphy was positive, whereas whole-body MRI failed to detect these metastases. In 77/129 (60%) patients, whole-body MRI revealed additional tumor-related findings. CONCLUSION: Whole-body MRI, as a new staging method, is superior to skeletal scintigraphy with respect to the detection of skeletal metastases and the extent of metastastic disease. Furthermore, whole-body MRI yields additional tumor-related findings. Therefore, whole-body MRI should be performed as an alternative to skeletal scintigraphy for the assessment of skeletal metastases.

Diagnostic value of MRI in comparison to scintigraphy, PET, MS-CT and PET/CT for the detection of metastases of bone.

The initial localization of metastases in the bone in patients with solid tumors has a relatively good prognosis in comparison with visceral metastasization. The early detection of bone marrow metastases allows for a rapid initiation of therapy and a subsequent reduction in the morbidity rate. Modern MRI is superior to the 30-year-old skeletal scintigraphy and bone marrow scintigraphy with respect to sensitivity, specificity, as well as the extent of osteal metastasis. MRI provides substantial, therapy-relevant additional information. MSCT plays an important role in the management of cancer patients in clinical routine and gives an excellent survey of the axial skeleton by demonstrating osteolytic and osteoblastic metastases. Extensive comparative studies of MRI with 18F-FDG-PET and 18F-fluoride-PET have not yet been carried out. Whole body MRI is a very promising new staging method for the oncological diagnosis of solid tumors and the detection of osteal metastases. The adoption of 18F-FDG-PET and 18F-fluoride-PET FDG as well as the side by side PET-CT image fusion and the two in one PET/CT examinations appears to be slightly less sensitive to whole body MRI in the detection of osteal metastases. Larger, prospective multicenter studies are necessary to establish these as new, promising methods for the detection of osteal metastases.

[Radiofrequency ablation of malignant lung tumours. Judicious approach?]. / Radiofrequenzablation maligner Lungentumore. Eine sinnvolle Methode?

BACKGROUND: Radiofrequency ablation (RFA) is a minimally invasive technique and well established in the treatment of malignant hepatic tumours. This method could also find application in patients with malignant lung tumours who, for functional reasons, have to be excluded from standard surgery. Until now, however, very little data have been available on the application of RFA in malignant pulmonary tumours. PATIENTS AND METHODS: From November 2001 to January 2004, eleven malignant lesions of the lung were treated with RFA. The indication for RFA resulted from an inadequate pulmonary reserve and additional severe risk factors. RESULTS: Eleven lesions were treated in ten patients with RFA. The malignancies were primary non-small cell bronchial carcinomas (n=9) as well as metastases of non-small cell carcinomas (n=2). Early complications of RFA were pneumothorax, hemorrhagic intrapleural effusion, bronchopleural fistula and pericarditis. Two weeks after RFA, pneumonia appeared as a late complication. No patient's death was related to the RFA procedure. After a mean follow-up of 8.5 months five patients died. Five patients are still alive, two of whom exhibit no tumour recurrence. CONCLUSION: RFA in patients with lung tumours is possible from a technical viewpoint. It is possibly a therapeutic alternative for patients with localized tumours that are inoperable. However, in this series, the morbidity of the procedure -- taking the degree of invasiveness into account -- is high, and the oncological results are unsatisfactory, possibly due to a small cohort of patients.

[Whole-body MRI in comparison to skeletal scintigraphy for detection of skeletal metastases in patients with solid tumors]. / Ganzkörper-MRT vs. Skelettszintigraphie bei der Detektion ossärer Metastasen solider Tumoren.

PURPOSE: The aim of this study was to compare the diagnostic efficacy of whole-body magnetic resonance imaging (WB-MRI) as a new and rapid examination technique with skeletal scintigraphy for detection of skeletal metastases from solid tumors. MATERIAL AND METHODS: In 129 patients with solid malignant tumors, WB-MRI was performed for individual comparison with skeletal scintigraphy. Examinations were performed with the innovative AngioSURF rolling table with integrated phased array surface coil and coronary TIRM sequences for different body regions. RESULTS: The results for WB-MRI and skeletal scintigraphy were concordant in 81% of the cases, whereby both procedures excluded skeletal metastases in 43%. WB-MRI and skeletal scintigraphy demonstrated skeletal metastases in 38% of the cases, whereby WB-MRI provided more comprehensive findings in 45%. In 12% of the cases, skeletal scintigraphy was superior to WB-MRI and in 19% the findings were discordant, whereby WB-MRI detected skeletal metastases in 15 cases which had not been found on skeletal scintigraphy. In nine cases, skeletal scintigraphy was positive when the WB-MRI was negative. In 60% of the cases, WB-MRI evidenced tumor-associated findings. CONCLUSION: WB-MRI represents a promising new staging technique for detection of skeletal metastases, which is more sensitive in many cases than skeletal scintigraphy in detecting and assessing the extent of skeletal metastases-and tumor-associated findings that are relevant for treatment strategy.

Gadolinium-enhanced elliptically reordered three-dimensional MR angiography in the assessment of hand vascularization before radial artery harvest for coronary artery bypass grafting: first experience.

RATIONALE AND OBJECTIVES: To assess the suitability of contrast-enhanced magnetic resonance angiography (MRA) in the preoperative evaluation of hand vasculature in potential candidates for radial artery bypass grafting. METHODS: In 21 patients, gadobenate dimeglumine-enhanced, three-dimensional gradient-echo sequences of both hands were performed, as well as a Doppler ultrasound study with radial artery compression. Doppler findings were correlated with MRA, focusing on the assessment of anastomoses between the vascular bed of the ulnar and radial arteries. RESULTS: One individual had to be excluded because of accidentally disclosed metal foreign bodies. Sufficient depiction of the hand vasculature was achieved in the remainder. Seventeen patients had evidence of adequate collateral flow between the ulnar and radial artery supply on Doppler ultrasound. Three patients exhibited inadequate collateral flow, with angiographic signs of vessel occlusion or missing collaterals between the palmar arches. Two patients presented with stenosis or occlusion of the radial artery. Magnetic resonance angiograms displayed great variations in hand vasculature and collateral formation, with no mismatch compared with Doppler ultrasound results. CONCLUSIONS: Contrast-enhanced MRA displays vascularization of the hand in detail and supplies ultrasound flow measurements for radial artery harvest, with high-resolution angiographic data about possible vessel variations and the presence of anastomoses between the radial or ulnar artery supply.

Structural intermediates in the putative pathway from the cellular prion protein to the pathogenic form.

The conversion of the alpha-helical, protease sensitive and noninfectious form of the prion protein (PrP(C)) into an insoluble, protease resistant, predominantly beta-sheeted and infectious form (PrP(Sc)) is the fundamental event in prion formation. In the present work, two soluble and stable intermediate structural states are newly identified for recombinant Syrian hamster PrP(90-231) (recPrP), a dimeric alpha-helical state and a tetra- or oligomeric, beta-sheet rich state. In 0.2% SDS at room temperature, recPrP is soluble and exhibits alpha-helical and random coil secondary structure as determined by circular dichroism. Reduction of the SDS concentration to 0.06% leads first to a small increase in alpha-helical content, whereas further dilution to 0.02% results in the aquisition of beta-sheet structure. The reversible transition curve is sigmoidal within a narrow range of SDS concentrations (0.04 to 0.02%). Size exclusion chromatography and chemical crosslinking revealed that the alpha-helical form is dimeric, while the beta-sheet rich form is tetra- or oligomeric. Both the alpha-helical and beta-sheet rich intermediates are soluble and stable. Thus, they should be accessible to further structural and mechanistic studies. At 0.01% SDS, the oligomeric intermediates aggregated into large, insoluble structures as observed by fluorescence correlation spectroscopy. Our results are discussed with respect to the mechanism of PrP(Sc) formation and the propagation of prions.

[Quality assessment using AGIR: results and experience]. / Qualitätsmanagement mittels AGIR: Ergebnisse und Erfahrungen.

PURPOSE: To evaluate whether a new software from the working group for interventional radiology (AGIR) is an appropriate tool for quality assurance in interventional radiology, and presentation of results acquired within the quality improvement process in 1999. PATIENTS AND METHODS: AGIR-defined parameters such as patient data, risk profile, given interventions as well as complications were registered by a recently developed software. Based on monthly data analyses, possible complications were identified and discussed in morbidity and mortality conferences. RESULTS: 1014 interventions were performed in our institution in 1999. According to criteria established by AGIR, the complication rate was 2.7%. In addition and according to SCVIR criteria, complications were distinguished quantitatively in five classes and semiquantitatively in minor and major groups. The result was a minor complication rate of 1.8%, and a major rate of 0.9%. There were no cases of death associated with the intervention. Further strategies were developed in order to reduce the complication rate. CONCLUSION: Extensive quality assurance methods can be integrated in daily routine work. These methods lead to an intensive transparency of treatment results, and allow the implementation of continuous quality improvements. The development of the software is a first step in establishing a nation-wide quality assurance system. Nevertheless, modification and additional definition of the AGIR predefined parameters are required, for example, to avoid unnecessary procedures.

Optimization of contrast-enhanced MR angiography of the hands with a timing bolus and elliptically reordered 3D pulse sequence.

Our objective was to optimize bolus administration and sequence setting in gadolinium-enhanced magnetic resonance (MR) angiography of the hands. Elliptically reordered three-dimensional (3D) spoiled gradient-echo sequence with non-slab-selective radio frequency excitation was optimized according to the measurements of arterial and venous time-signal curves in 21 patients. Great variations in bolus arrival time and arterio-venous transit time could be observed. In most patients high-quality arterial depiction could be obtained with minor venous contamination. Contrast-to-noise, spatial resolution, and selective arterial filling is still a challenge for 3D MR angiography of the hand but can be optimized using Gadolinium-BOPTA and a dedicated pulse sequence setting with exact bolus timing.

Cerivastatin prevents angiotensin II-induced renal injury independent of blood pressure- and cholesterol-lowering effects.

BACKGROUND: Statins are effective in prevention of end-organ damage; however, the benefits cannot be fully explained on the basis of cholesterol reduction. We used an angiotensin II (Ang II)-dependent model to test the hypothesis that cerivastatin prevents leukocyte adhesion and infiltration, induction of inducible nitric oxide synthase (iNOS), and ameliorates end-organ damage. METHODS: We analyzed intracellular targets, such as mitogen-activated protein kinase and transcription factor (nuclear factor-kappaB and activator protein-1) activation. We used immunohistochemistry, immunocytochemistry, electrophoretic mobility shift assays, and enzyme-linked immunosorbent assay techniques. We treated rats transgenic for human renin and angiotensinogen (dTGR) chronically from week 4 to 7 with cerivastatin (0.5 mg/kg by gavage). RESULTS: Untreated dTGR developed hypertension, cardiac hypertrophy, and renal damage, with a 100-fold increased albuminuria and focal cortical necrosis. dTGR mortality at the age of seven weeks was 45%. Immunohistochemistry showed increased iNOS expression in the endothelium and media of small vessels, infiltrating cells, afferent arterioles, and glomeruli of dTGR, which was greater in cortex than medulla. Phosphorylated extracellular signal regulated kinase (p-ERK) was increased in dTGR; nuclear factor-kappaB and activator protein-1 were both activated. Cerivastatin decreased systolic blood pressure compared with untreated dTGR (147 +/- 14 vs. 201 +/- 6 mm Hg, P < 0.001). Albuminuria was reduced by 60% (P = 0.001), and creatinine was lowered (0.45 +/- 0.01 vs. 0.68 +/- 0.05 mg/dL, P = 0. 003); however, cholesterol was not reduced. Intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression was diminished, while neutrophil and monocyte infiltration in the kidney was markedly reduced. ERK phosphorylation and transcription factor activation were reduced. In addition, in vitro incubation of vascular smooth muscle cells with cerivastatin (0.5 micromol/L) almost completely prevented the Ang II-induced ERK phosphorylation. CONCLUSION: Cerivastatin reduced inflammation, cell proliferation, and iNOS induction, which led to a reduction in cellular damage. Our findings suggest that 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase inhibition ameliorates Ang II-induced end-organ damage. We suggest that these effects were independent of cholesterol.

A case of spinal glioblastoma multiforme: immunohistochemical study and review of the literature.

A 31-year old female underwent subtotal resection of a spinal glioblastoma multiforme (GBM) at level D 10/11 in June 1997. Immunohistochemistry revealed increased MIB-1 labeling index and accumulation of p53 protein. Routine MRI in February 1998 showed multiple tumors of the lumbar spinal cord. At open biopsy, diffuse infiltration of multiple radices was seen. Histologically and immunohistochemically, the tumor was similar to the primary. In May 1998, MRI revealed multiple intracranial metastases and meningeal involvement. The patient died in June 1998, 13 months after the onset of symptoms. The lifes of patients with spinal gliomas are not endangered by direct compression of the brain stem, and systemic metastases are extremely uncommon with gliomas. Yet, survival times in the reported case and in the literature are not better than with cerebral localization. Analysis of the present case and a survey of the literature indicate that CSF involvement and consecutive intracranial seeding determine the prognosis of patients with spinal GBM. Thus, regular monitoring of CSF-cytology and/or spinal MRI appear to be advisable in spinal GBM.

Indirect MR arthrography of the unexercised glenohumeral joint in patients with rotator cuff tears.

RATIONALE AND OBJECTIVES: To evaluate the diagnostic utility of indirect MR arthrography of the unexercised glenohumeral joint in patients with rotator cuff tears confirmed by arthroscopy or arthrotomy as the gold standard. METHODS: Twenty-six patients underwent conventional MR imaging and indirect MR arthrography of the stationary glenohumeral joint using a wrap-around surface coil. Unenhanced T1-weighted spin echo/T2-weighted fast spin echo sequences and T1-weighted gradient echo sequences, adding spectral fat suppression after intravenous administration of contrast medium, were performed in the oblique coronal and oblique sagittal planes. Images were analyzed by three experienced radiologists in consensus. Levels of diagnostic confidence were evaluated using a four-point scale of diagnostic certainty. RESULTS: Performing indirect MR arthrography of the unexercised shoulder leads to a diagnostically efficient enhancement of joint fluid (120% at 4 minutes and 145% at 8 minutes after intravenous injection of gadodiamide). In terms of soft tissue delineation, characterization of rotator cuff tears was significantly improved by using enhanced fat-suppressed T1-weighted gradient echo sequences compared with conventional MR imaging. CONCLUSIONS: Indirect MR arthrography without glenohumeral joint exercise in the diagnosis of rotator cuff tears is feasible and represents a more convenient and less time-consuming alternative to indirect MR arthrography after joint exercise.

[Kinematic versus static MRI study of the cervical spine in patients with rheumatoid arthritis]. / Kinematische versus statische MRT-Untersuchung der Halswirbelsäule bei Patienten mit rheumatoider Arthritis.

PURPOSE: The objective of this study was to compare the diagnostic value of cinematic magnetic resonance imaging with static MRI examinations in patients with rheumatoid arthritis and concomitant attack of the cervical spine. METHODS: Dynamic functional MRI examinations of the cervical spine were performed one five subjects without complaints and 20 patients with rheumatoid arthritis. For the functional studies, a positioning frame was used that allowed infinitely variable forward and backward inclinations of the head. RESULTS: Functional magnetic resonance imaging made possible a sufficiently good differentiation of the extension of pannus tissue cranial, ventral, and dorsal of the dens with possible displacing and impinging effects on the spinal cord during flexing and stretching movements. In addition, it is suitable for demonstration of the degree of instability in the atlanto-occipital and atlanto-axial planes. In contrast to conventional X-rays, CT, and static MRI, basilary impression as well as compressions and angulations of the cervical bone marrow are better visualized by cinematic magnetic resonance tomography. CONCLUSIONS: Functional magnetic resonance tomography is an important diagnostic method for the induction of the cervical spine in patients with rheumatoid arthritis. In particular, fusion and instabilities as well as compressions of the bone marrow often can only be detected with the help of functional MRI.

Rapid acquisition of beta-sheet structure in the prion protein prior to multimer formation.

The N-terminally truncated form of the prion protein, PrP 27-30, and the corresponding recombinant protein, rPrP, were solubilized in 0.2% SDS, and the transitions induced by changing the conditions from 0.2% SDS to physiological conditions, i.e. removing SDS, were characterized with respect to solubility, resistance to proteolysis, secondary structure and multimerization. Circular dichroism, electron microscopy and fluorescence correlation spectroscopy were used to study the structural transitions of PrP. Within one minute the alpha-helical structure of PrP was transformed into one that was enriched in beta-sheets and consisted mainly of dimers. Larger oligomers were found after 20 minutes and larger multimers exhibiting resistance to proteolysis were found after several hours. It was concluded that the monomeric alpha-helical conformation was stable in SDS or when attached to the membrane; however, the state of lowest free energy in aqueous solution at neutral pH seems to be the multimeric, beta-sheet enriched conformation.