Investigation of pH-Responsiveness inside Lipid Nanoparticles for Parenteral mRNA Application Using Small-Angle X-ray Scattering

Messenger ribonucleic acid (mRNA)-based nanomedicines have shown to be a promising new lead in a broad field of potential applications such as tumor immunotherapy. Of these nanomedicines, lipid-based mRNA nanoparticles comprising ionizable lipids are gaining increasing attention as versatile technologies for fine-tuning toward a given application, with proven potential for successful development up to clinical practice. Still, several hurdles have to be overcome to obtain a drug product that shows adequate mRNA delivery and clinical efficacy. In this study, pH-induced changes in internal molecular organization and overall physicochemical characteristics of lipoplexes comprising ionizable lipids were investigated using small-angle X-ray scattering and supplementary techniques. These changes were determined for different types of ionizable lipids, present at various molar fractions and N/P ratios inside the phospholipid membranes. The investigated systems showed a lamellar organization, allowing an accurate determination of pH-dependent structural changes. The differences in the pH responsiveness of the systems comprising different ionizable lipids and mRNA fractions could be clearly revealed from their structural evolution. Measurements of the degree of ionization and pH-dependent mRNA loading into the systems by fluorescence assays supported the findings from the structural investigation. Our approach allows for direct in situ determination of the structural response of the lipoplex systems to changes of the environmental pH similar to that observed for endosomal uptake. These data therefore provide valuable complementary information for understanding and fine-tuning of tailored mRNA delivery systems toward improved cellular uptake and endosomal processing.

Introducing a soil universal model method (SUMM) and its application for qualitative and quantitative determination of poly(ethylene), poly(styrene), poly(vinyl chloride) and poly(ethylene terephthalate) microplastics in a model soil

Methods for analysis of microplastic in soils are still being developed. In this study, we evaluated the potential of a soil universal model method (SUMM) based on thermogravimetry (TGA) for the identification and quantification of microplastics in standard loamy sand. Blank and spiked soils (with amounts of one of four microplastic types) were analyzed by TGA. For each sample, thermal mass losses (TML) in 10 °C intervals were extracted and used for further analysis. To explain and demonstrate the principles of SUMM, two scenarios were discussed. The first refers to a rare situation in which an uncontaminated blank of investigated soil is available and TML of spiked and blank soils are subtracted. The results showed that the investigated microplastics degraded in characteristic temperature areas and differences between spiked and blank soils were proportional to the microplastics concentrations. The second scenario reflects the more common situation where the blank is not available and needs to be replaced by the previously developed interrelationships representing soil universal models. The models were consequently subtracted from measured TML. Sparse principal component analysis (sPCA) identified 8 of 14 modeled differences between measured TMLs and the universal model as meaningful for microplastics discrimination. Calibrating various microplastics concentrations with the first principal component extracted from sPCA resulted in linear fits and limits of detection in between environmentally relevant microplastics concentrations. Even if such an approach using calculated standards still has limitations, the SUMM shows a certain potential for a fast pre-screening method for analysis of microplastics in soils.

Metaproteome analysis reveals that syntrophy, competition, and phage-host interaction shape microbial communities in biogas plants

BACKGROUND

In biogas plants, complex microbial communities produce methane and carbon dioxide by anaerobic digestion of biomass. For the characterization of the microbial functional networks, samples of 11 reactors were analyzed using a high-resolution metaproteomics pipeline.

RESULTS

Examined methanogenesis archaeal communities were either mixotrophic or strictly hydrogenotrophic in syntrophy with bacterial acetate oxidizers. Mapping of identified metaproteins with process steps described by the Anaerobic Digestion Model 1 confirmed its main assumptions and also proposed some extensions such as syntrophic acetate oxidation or fermentation of alcohols. Results indicate that the microbial communities were shaped by syntrophy as well as competition and phage-host interactions causing cell lysis. For the families Bacillaceae, Enterobacteriaceae, and Clostridiaceae, the number of phages exceeded up to 20-fold the number of host cells.

CONCLUSION

Phage-induced cell lysis might slow down the conversion of substrates to biogas, though, it could support the growth of auxotrophic microbes by cycling of nutrients.

Infrared thermography of the pig thorax: an assessment of selected regions of interest by computed tomographical and anatomical parameters

Current methods of diagnosis of respiratory diseases in swine are invasive, time‐consuming and expensive. Infrared thermography (IRT) of the thorax might provide a new method of high specificity to select swine affected with lung alterations for further diagnostics. In this study, layer thickness of different tissues was determined in frozen thorax slices (FTS) by computed tomography (CT) and then related to skin temperatures measured by IRT in healthy pigs. The aim was to determine appropriate regions of interest (ROI) for evaluation of IRT images. Organ layer thicknesses measured in CT images correspond to those measured in FTS. Temperature differences between lung ROIs and abdomen ROIs were positively correlated with lung layer thickness at certain localizations, and negatively correlated with the thickness of the thorax wall and of inner organ layers. Reference values of differences between skin temperatures were established for two ROIs on the thorax with potential practical use for lung health status determination. Respective ROIs were located on vertical lines crossing the 7th (right) and the 10th (left) thoracic vertebrae. The presence of ribs affected skin temperature significantly.

[Rare injury from blunt abdominal trauma in a child]

Presented in this work is a rare injury of a blunt abdominal trauma in a child. Besides a partial rupture of the kidney and a retro-/intraperitoneal haematoma, a further injury occurred from the accident: an initially clinically indetectable tear of the A. iliaca communis which was found intraoperatively and with systematic CT analysis. Traumatic blood vessel lesions of the abdominal aorta and in particular the iliac blood vessels are very rare in children. By such violent impact injuries, it is therefore vital to perform a clinical examination of the foot pulse, systematic analysis of radiology diagnostics, and intraoperative exploration. The growth phase should be considered for therapy of the blood vessels depending on the child's age group. As the long-term results of graft implants are practically unknown, if possible a primary suture or vein patch should be performed.

Magnetic Resonance Female Breast Imaging (MRFBI) - Evaluation of the Changes in Signal Intensity over Time Pre- and Post-administration of 0.2 mmol/kg Gd-DTPA

PURPOSE

We are looking for a threshold value to discriminate between benign and malign breast lesions in MRI of female breast after administration of 0.2 mmol Gadolinum-DTPA/kg bw.

MATERIALS AND METHODS

Double coil breast MRI (1.5 Tesla) were performed in 65 patients with an suspicious lesion for malignancy in an anteriorly examination. 57 patients could be evaluated in our study design. Histopathological 35 patients had an invasive carcinoma, 3 patients had an in-situ-carcinoma and in 27 patients benign changes were found.

RESULTS

For different carcinoma diameters we found a different increase of signal intensity (SI): small carcinoma (< 10 mm) had an maximum increase of SI of 102 %, medium sized (10 to 20 mm) 222 % and carcinomas over 20 mm showed an increase of 271 %. We did not find a significant difference between SI in benign and malign lesions. The sensitivity was 94.6 % the specificity 65 %.

CONCLUSION

A threshold value to distinguish between malign and benign in MRI could not be defined. With the double normal Gd-DTPA dose we do not have better specificity and sensitivity than for normal dose (0.1 mmol/kg bw) is described.

[Cutting speeds and success of biopsy with different punch biopsy instruments]

PURPOSE

The goal of our investigations was the verification of the relationship between the reachable cutting speed and the biopsy success for different large-core needle biopsy devices in dependence of the cutting depth as well as different kinds of tissue.

METHODS

We measured the dynamic cutting properties of five large-core needle devices with moveable outer needles in air and different tissues. An incremental stripe had been attached on to the outer needle and was moved through a photooptical sensor during the cutting phase. For the valuation of the biopsy success we compared the absolute weight respectively the volume of the tissue probes as well as the relative weight in relation to the size of the sample chambers within the inner trocars.

RESULTS

A clear correlation between the cutting speed, the tissue properties and the biopsy success had been registered, especially for more solid tissues.

CONCLUSIONS

For a successful large-core needle biopsy a cutting speed of 8 to 12 metres per second is essential. To compensate slower needle movements high quality requirements for the surface, geometry and edge have to be fulfilled.

Rapid enrichment and detection of melanoma cells from peripheral blood mononuclear cells by a new assay combining immunomagnetic cell sorting and immunocytochemical staining

Commonly used methods for detection of melanoma cells in blood, including RT-PCR and immunocytochemistry, display only a limited sensitivity and specificity. Reliable detection of less than one melanoma cell per ml of blood is hardly possible using these methods. To obtain greater sensitivity so that a single melanoma cell in up to 25 ml of blood can be detected (5 x 10(7) peripheral blood mononuclear cells, or PBMC), we developed a new assay for combined enrichment and immunocytochemical detection of disseminated melanoma cells from PBMC of patients with malignant melanomas. Melanoma cells are directly magnetically labeled using colloidal superparamagnetic microparticles approximately 60 nm in diameter conjugated to the anti-melanoma monoclonal antibody 9.2.27, with no reactivity to normal cells in blood. Magnetically labeled melanoma cells are enriched from PBMC by magnetic cell separation and detected by a new approach for immunocytochemical staining with monoclonal mouse anti-melanoma antibodies (anti-MelanA and HMB-45). The efficiency of this assay was demonstrated in a model system in which 5-500 tumor cells from the melanoma cell line SK-MEL-28 were seeded into PBMC samples from healthy donors containing 5 x 10(7) leukocytes. Mean recovery of the seeded tumor cells was 47.4 +/- 13.99% (n = 15). Applying the assay to 20-50 ml blood samples of patients with stage III-IV malignant melanomas, we were able to detect melanoma cells in two of eight patients (25%).

Pre-operative staging of cervical cancer: comparison of magnetic resonance imaging (MRI) and computed tomography (CT) with histologic results

Thirty-two patients with histologically confirmed cervical carcinoma were preoperatively investigated using MRI; in addition, a CAT-scan was performed on 15 of these patients. The diagnostic results using both modalities were compared with the histological findings (after hysterectomy according to Wertheim-Meigs, including lymph node dissection in the pelvic and, in part, in para-aortal regions). Determination of tumour volume was possible with high accuracy using MRI. Accuracy in assessing the parametria was 86%, vagina 90%, bladder and rectum 97%. The shortcoming of MRI is still the detection of infiltrated lymph nodes. The accuracy of 69% achieved for lymph nodes is equal to results with computed tomography. The general accuracy for our patients in staging was 81% for MRI versus 47% for CT. MRI-based diagnosis enables us to determine a correct tumour staging preoperatively, and is therefore very helpful in planning an adequate therapy. If MRI were used more widely it would contribute to simplification and shortening of the preoperative diagnostic procedure in patients with cervical carcinoma.

1H and 31P NMR characterisation of a double breast coil for spectroscopic measurements and imaging

For the first time a double turn breast coil has been described which can be used for 1H imaging, 1H spectroscopy and 31P spectroscopy. The paper describes basic technical features of the coil, coil design, B1 field/excitation field distribution for 1H and 31P, sensitivity, and feasibility for 31P spectroscopic in vivo studies. The main advantage of the double frequency tuneable coil is that 1H imaging for tumor localization and 31P spectroscopy for response control can be done without an additional repositioning of the patient.

Fluoride release/uptake of polyacid-modified resin composites (compomers) in neutral and acidic buffer solutions

The aim of the present study was to evaluate the fluoride uptake/release of polyacid-modified resin composites (compomers) in neutral and acidic buffer solutions. Two compomers (Dyract and Compoglass) were tested and the conventional glass-ionomer cement (GIC) Vivaglass Base served as a control. Forty specimens were fabricated from each of the respective materials. Twenty of these specimens were placed in artificial saliva and the other 20 specimens in a fluoridated dentifrice slurry for 5 min. Then, 10 fluoridated and 10 non-fluoridated specimens were immersed in a neutral buffer solution (pH 6.8), and the other specimens were immersed in an acidic solution (pH 4.0). After 1, 2, 3, 4, and 5 days the samples were again placed in either a fluoridated dentifrice slurry or saliva for 5 min, after which time they were transferred to fresh buffer solutions. The fluoride content of the solutions was assessed with a fluoride sensitive electrode. Fluoride release from all the materials decreased continuously during the experiment, with a significantly higher release in the acidic solution compared to the neutral buffer solution. Fluoridation did not result in an increased fluoride release for the compomers. However, the conventional GIC revealed a significantly higher fluoride release after fluoridation. It is concluded that Dyract and Compoglass can not be replenished with fluoride, irrespective of the pH value of the environment.

[Optimal use of MRI mammography from the economic viewpoint]

With the introduction of the contrast agent gadolinum DTPA there were hopes that "MRM" would prove to be the investigatory technique that would largely solve the problems of breast diagnostics. However, after the early years of acceptance, the new method of investigation became a subject of controversy. Nonetheless, MRM today occupies a recognized place in diagnostics for certain indications. It is still true, however, that reliable use of this procedure requires a great deal of experience, since there is a relatively large area of overlap between benign and malignant tumors. Further, the costs are significantly higher than those for conventional methods of investigation. New studies that have been conducted at the Charité, Campus Virchow Medical Center in Berlin, suggest that, if one takes the relevant indications into account, MRM can be economic and contribute significantly to cost reduction. Application of a newly developed software package has shown that the good discrimination in a suspect area resulting from contrast agent enhancement makes possible a reliable differentiation between malignant and benign tissue changes. A further result was that, when certain boundary conditions are satisfied, a contrast agent bolus of 0.1 mmol/kg BW is sufficient, making a double dose (0.2 mmol/kg BW) unnecessary.

[Cervix carcinoma: staging, therapy, after-care. Experiences with magnetic resonance tomography of cervix carcinoma based on recent literature 1993 to 1997]

The investigation of cervix carcinoma with magnetic resonance tomography (MRT) is still controversially discussed with regard to its diagnostic value as well as for planning radiation therapy. The purpose of this article is to present and discuss papers published between 1993 and 1997 in this field with respect to the technique used, the contrast media applied and its clinical value. A literature search using three different databases (Medline, Embase, Cancerlit) identified 39 publications, which were then analysed. Despite the partially suboptimal presentation of results in these papers MRT proved superior to other imaging modalities. Due to better demarcation of cervix carcinoma with MRT, it was possible to calculate tumor value as well as to correctly judge the infiltrative character. This allows for a more precise treatment and staging of the patient's prognosis. In the future, MRT might be useful in diagnosing recurrence at relatively early stage. Unfortunately lymphatic nodes can only be insufficiently verified using MRT.

[Effects of para- and diamagnetic materials in a 1.5 Tesla high field magnetic resonance tomography system]

This article shows the results of an experimental investigation of the interference by paramagnetic and diamagnetic materials on imaging in a closed 1.5 Tesla high field magnetic resonance imaging system (MRI). For different types of sequences (SE, GE, EPI) the effects of metal and non-metal profiles in producing artefacts were investigated. A phantom (plastic trunk) filled with Gd-Mn-solution was used for representation of the artefacts. The materials analysed were placed parallel to the phantom at predetermined distances. The images were obtained in transverse and sagittal planes and analysed with respect to the resulting artefacts. The results show that aluminum and polymer profiles produce the weakest artefacts, even when the material is positioned close to the phantom. A comparison of the sequence types shows that the SE-sequence has a low sensitivity to artefacts, despite the great profile variation in size and shape. The SE-sequence accordingly showed a higher imaging stability as compared with the GE- and EPI-sequences. Steel and copper produced the strongest artefacts. The examination was begun after an intensive study of the literature (Internet, Medline, Meditec). So far have been few publications on this subject.

[Imaging tumor extension of renal cell carcinomas with magnetic resonance tomography. Improved tumor-tissue contrast with Gd-DTPA-assisted spin-echo sequences and simultaneous fat suppression]

PURPOSE

To evaluate the use of contrast-enhanced T1-weighted images with fat suppression (T1FS) to improve the contrast-to-noise ratio of renal cancer and renal parenchyma as well as perirenal fat.

METHODS

25 patients with histologically proven unilateral renal cancer after nephrectomy were examined before surgery. In addition to plane and contrast-enhanced T1-weighted as well as T2-weighted spin-echo images, all patients had T1 FS immediately after administration of Gd-DTPA in two planes. The contrast-to-noise ratio was calculated using circular regions-of-interest which outlined the tumor, the renal parenchyma, pyelon, and the perirenal fat.

RESULTS

T1 FS significantly improved the contrast-to-noise ratio of renal cancer and renal parenchyma compared to all conventional spinecho sequences (p < 0.001; Wilcoxon-Test). Compared to contrast-enhanced T1-weighted images without fat-suppression T1 FS yielded a higher CNR of the tumor, the perirenal fat and the pyelon. Another advantage was the absence of the chemical-shift artifact which is mostly pronounced in T2-weighted images and a reduced number of observed artifacts due to breathing.

CONCLUSION

T1 FS should replace conventional contrast-enhanced T1-weighted spin-echo images in the work-up of renal cancer using MRI.

Immunomagnetic enrichment of disseminated epithelial tumor cells from peripheral blood by MACS

Disseminated epithelial tumor cells have been detected in the bone marrow and blood of cancer patients by means of immunocytochemical or immunofluorescent staining of cytocentrifuge slides, multiparameter flow cytometry, and reverse transcriptase-polymerase chain reaction. However, it is hardly possible using such methods to detect tumor cells at a frequency below 10(-6). To increase the sensitivity of these detection techniques we have developed a new technology for the enrichment of disseminated epithelial tumor cells from hematopoietic cell samples by high-gradient magnetic cell sorting (MACS). Cells are permeabilized and fixed and carcinoma cells are magnetically labeled specifically with an anti-cytokeratin 8 monoclonal antibody (mAb) directly conjugated to superparamagnetic microbeads. Magnetically labeled cells are enriched on high-gradient magnetic columns. Tumor cells are detected in the enriched cell fraction by flow cytometry, fluorescence microscopy, or immunocytochemisty. In this study we demonstrated the method using a model system in which five to 5,000 cells from a breast cancer cell line were seeded into blood cell samples from a healthy donor containing 1.2 x 10(8) leukocytes. Tumor cells were 10,477+/-4242 (n=25)-fold magnetically enriched, and 57.7%+/-16.9% (n=33) of the initially seeded tumor cells were recovered. Applying the method to 20-40 mL blood samples from patients with advanced carcinomas of the breast, prostate, colon, rectum, or lung, we were able to detect between one and 6.8 x 10(4) cytokeratin-expressing tumor cells in 21 of 34 patients. This corresponds to frequencies of tumor cells between 6.8 x 10(-9) and 1.1 x 10(-3) among nucleated cells in the original sample. Enriched tumor cells were further analyzed for expression of tissue-specific and prognostic markers such as breast mucin glycoproteins, erbB2, and CD44v6 for additional characterization and to confirm their tumor origin. The technique described could become a valuable tool for the quantification and molecular characterization of metastatic carcinoma cells in hematopoietic tissue, and may ultimately prove useful in the diagnosis, prognosis, and monitoring of patients with carcinoma.

Boeck sarcoidosis of the breast: mammographic, ultrasound, and MR findings

The rare case of sarcoidosis of the breast is presented. The mammographic, ultrasound, and MR appearances are described.

Skeletal muscle-specific myosin binding protein-H is expressed in Purkinje fibers of the cardiac conduction system

Heart contraction is coordinated by conduction of electrical excitation through specialized tissues of the cardiac conduction system. By retroviral single-cell tagging and lineage analyses in the embryonic chicken heart, we have recently demonstrated that a subset of cardiac muscle cells terminally differentiates as cells of the peripheral conduction system (Purkinje fibers) and that this occurs invariably in perivascular regions of developing coronary arteries. Cis regulatory elements that function in transcriptional regulation of cells in the conducting system have been distinguished from those in contractile cardiac muscle cells; eg, 5' regulatory sequences of the desmin gene act as enhancer elements in skeletal muscle and in the conduction system but not in cardiac muscle. We hypothesize that Purkinje fiber differentiation involves a switch of the gene expression program from that characteristic of cardiac muscle to one typical of skeletal muscle. To test this hypothesis, we examined the expression of myosin binding protein-H (MyBP-H) in Purkinje fibers of chicken hearts. This unique myosin binding protein is present in skeletal but not cardiac myocytes. A site-directed polyclonal antibody (AB105) was generated against MyBP-H. Immunohistological analysis of the myocardium mapped the AB105 antigen predominantly to A bands of myofibrils within Purkinje fibers. Western blot analysis of whole extracts from the ventricular wall of adult chicken hearts revealed that the AB105 epitope was restricted to a single protein of approximately 86 kD, the same size as MyBP-H in skeletal muscle. Biochemical properties of the Purkinje fiber 86-kD protein and RNase protection analyses of its mRNA indicate that Purkinje fiber 86-kD protein is indistinguishable from skeletal muscle MyBP-H. The results provide evidence that skeletal muscle MyBP-H is expressed in a subset of cardiac muscle cells that differentiate into Purkinje fibers of the heart.

Is there a correlation in breast carcinomas between tumor size and number of tumor vessels detected by gadolinium-enhanced magnetic resonance mammography?

Tumor vessels are known as a sign of malignancy in breast tumors. Is there a correlation between tumor size and the number of vessels in cases of breast tumor examined by dynamic gadolinium (Gd)-enhanced MR imaging? Eighteen patients (mean age, 46 +/- 7 years) underwent dynamic Gd-enhanced MR imaging of the breast by three-dimensional gradient echo sequence using thin-layer technique (2.5 mm) at 1.5T. The dynamic study included one precontrast and four postcontrast sequences (every 90 seconds) in coronal slices. Postprocessing by subtraction method and reconstruction in both transverse and sagittal planes were performed. All carcinomas showed rapid Gd enhancement. Tumor size (0.5 to 31.5 cm3; mean, 6.3 +/- 3.7 cm3) and number of vessels (1 to 10; mean, 3 +/- 2.1) were detected in summation of all three directions. A significant correlation was found between number of vessels and tumor size (r = 0.787, p < or = 0.01). Breast tumor size significantly correlated with the number of vessels detected by Gd-enhanced MR mammography. The introduced method is a further important step in differentiating a carcinoma from a benign lesion.

[Diagnostic value of magnetic resonance tomography of the upper ankle joint--imaging of ligaments and tendons in standard slice orientation]

PURPOSE

Evaluation of the capability of high field strength MRI in depicting clinically important tendons and ligaments of the ankle joint using slice orientations parallel to the standard space directions without angulation.

MATERIALS AND METHODS

65 patients whose ankle joint complaints were not sufficiently clarified by conventional radiology sphere underwent MRI using plain T1-weighted spin echo sequences. Tendons and ligaments were classified by three independent radiologists with regard to their perceptibility on images of the different slice orientations.

RESULTS

Good perceptibility of at least two-thirds of each structure with the possibility for a decision regarding continuity or rupture of the remaining part was given most frequently in the following slice orientations: Axially for the tendons of peroneus longus, peroneus brevis, tibialis posterior, flexor digitorum longus, flexor hallucis longus, tibialis anterior, extensor digitorum longus, and extensor hallucis longus muscles, and for the calcanear tendon (each over 94% of cases), anterior (68%) talofibular ligament, deltoid (77%), anterior (63%), and posterior (72%) tibiofibular ligaments and coronally for the calcaneofibular (39%) and posterior talofibular ligaments (70%). The sagittal orientation was never the favoured one.

CONCLUSIONS

All tendons and ligaments of the ankle joint, except for the calcaneofibular and anterior tibiofibular ligaments, can be sufficiently visualized in the majority of cases by non-angulated spin echo sequences in standard slice orientations if the examination is performed in at least two slice directions. Thus, the minimal examination program should be: one T2-weighted sequence, T1-weighted sequences axially and in a further orientation, i.e. slightly angulated coronally for depicting the calcaneofibular ligament.

[MR urography with the T2-weighted turbo-spin-echo sequence]

Tumor-induced dilatation of the urinary tract is difficult to diagnose in the distal part of the ureter, including the stenosis, by ultrasound and X-ray. Often on account of renal insufficiency and allergy, i.v.-contrast media cannot be used. The present study should show the suitability of fast T2-weighted (turbo-) spin-echo sequences (T2-TSE) for MR-urography (MRU). Seven patients (62.3 +/- 6.1 years) were examined in the coronal plane with T2-TSE sequence (TR = 4500 ms, TE = 160 ms) and an MRU was calculated by using the MIP method (maximal intensity projection). This technique enabled urogram-like morphological representation of dilated urinary tract including stenosis in 6 of 7 patients. Assuming a high magnetic field homogeneity, MRU by using a T2-TSE-sequence, without i.v.-contrast media administration, can visualize the urinary tract dilatation and localize tumor-induced stenosis.

[Digital image intensification radiography in endoscopic retrograde cholangiopancreatography]

The standard in ERCP is the use of the conventional radiography system. Digital radiography system are very seldom used in ERCP, and then mostly by digital luminescence radiography. In this study we report our experience with digital image amplification radiography (DIAR) in ERCP. We examined 53 patients of clinical routine aged from 21 to 90 years. During the ERCP we used the X-ray statues and the real-time exposures. At the end of an examination the image post-processing followed. Both conventional and digital image amplification radiography needed the same examination conditions. The special X-ray protection (special lead-shields) used at digital ERCP did not hinder the examination. The DIAR provided at least the same amount of information as conventional radiography. An advantage of DIAR is the possibility of image post-processing such as contrast change, zooming, etc., and the digital archiving and communication. The examination time was reduced by about 30% as compared conventional ERCP, resulting in a reduction of the X-ray exposure time for the patients. The disadvantages of DIAR can surely be compensated by a high ERCP-rate.

[The behavior of central and peripheral hemodynamics in isometric and dynamic stress in hypertensive patients treatment with regular sauna therapy]

Effective treatment of hypertension includes decrease of blood pressure at rest, dynamic and isometric exercise. Therefore, we investigated the hemodynamic changes by radiocardiography (central hemodynamic) and Xenon-133-muscle clearance (peripheral hemodynamic) before and after a sauna treatment during a period of 3 months. 46 hypertensive men (WHO I-II, aged 41 +/- 11 years) participated in the study. Systolic and diastolic blood pressure at rest and during dynamic exercise were decreased significantly (p < or = 0.01) by sauna therapy. Change of blood pressure at isometric exercise was not significant (from 157.5 +/- 16.5 mmHg to 155.0 +/- 15.4 mmHg). The changes of cardiac output and total peripheral resistance were also not significant. Half-time of muscle clearance decreased significantly (from 4.4 +/- 1.9 min to 3.2 +/- 1.2 min, p < or = 0.01) and functional cross-section A increased significantly (from 3.8 +/- 0.9 mm2.c to 4.4 +/- 0.9 mm2.c, p < or = 0.01) after the sauna therapy at dynamic exercise, but not at isometric exercise. These results show the changes between isometric and dynamic exercise, which can only be explained well by a study of peripheral hemodynamic. Contrary to dynamic exercise, sauna therapy did not significantly decrease blood pressure at isometric exercise.

[The use of the T2-weighted turbo-spin-echo sequence in studying the neurocranium. A comparison with the conventional T2-weighted spin-echo sequence]

T2-weighted spin-echo imaging is the standard screening procedure in MR imaging of the neurocranium. We evaluated fast spin-echo T2-weighted imaging (TT2) of the neurocranium in comparison to conventional spin-echo T2-weighted imaging (T2). Signal-to-noise and contrast-to-noise ratio of normal brain tissues (basal ganglia, grey and white matter, CSF fluid) and different pathologies were calculated. Signal-to-noise ratio and contrast-to-noise ratio were significantly higher in TT2 than in T2 (with the exception of gray-to-white matter contrast). Tissues with increased content of water protons (mobile protons) showed the highest contrast to surrounding tissues. The increased signal intensity of fat must be given due attention in fatty lesions. Because the contrast-to-noise ratio between white matter and basal ganglia is less in TT2, Parkinson patients have to be examined by conventional T2. If these limitations are taken into account, fast spin-echo T2-weighted imaging is well appropriate for MR imaging of the neurocranium, resulting in heavy T2-weighting achieved in a short acquisition time.