Molecular resolution electron micrographs of monolamellar paraffin crystals.

A liquid helium-cooled cryoelectron microscope, operated to expose the specimen to only a very low electron dose, was used to obtain structural images of monolamellar n-tetratetracontane (n-C44H90) crystals at 0.25-nanometer resolution. These results are in contrast to earlier predictions that such extremely beam-sensitive materials could not be studied directly at this level of detail. Analysis of the resultant lattice images gives direct evidence for crystal bending as well as direct visualization of edge dislocations in this material.

Electron imaging of crotoxin complex thin crystal at 3.5 A.

Crotoxin complex forms thin crystals which are suitable for electron crystallographic analysis. We have used a 100 kV electron microscope equipped with a superconducting lens to image this crystal embedded in glucose. Optical diffraction analysis of the micrographs show unambiguously a structural resolution of 3.9 A which has not been obtained with the conventional microscope at room temperature. A density map with a nominal resolution of 3.5 A has been synthesized from these images by computer processing techniques.

Densely packed beta-structure at the protein-lipid interface of porin is revealed by high-resolution cryo-electron microscopy.

Porin is an integral membrane protein that forms channels across the outer membrane of Escherichia coli. Electron microscopic studies of negatively stained two-dimensional porin crystals have shown three stain accumulations per porin trimer, revealing the locations of pores spanning the membrane. In this study, reconstituted porin lattices embedded in glucose were investigated using the low-dose technique on a cryo-electron microscope equipped with a helium-cooled superconducting objective lens. The specimen temperature was maintained at 5 K to yield an improved microscopic and specimen stability. Under these conditions, we obtained for the first time electron diffraction patterns from porin lattices to a resolution of 3.2 A and images showing optical diffraction up to a resolution of 4.9 A. Applying correlation averaging techniques to the digitized micrographs, we were able to reconstruct projected images of the porin trimer to a resolution of up to 3.5 A. In the final projection maps, amplitudes from electron diffraction and phases from these images were combined. The predominant feature is a high-density narrow band (about 6 A in thickness) that delineates the outer perimeter of the trimer. Since the molecule consists of almost exclusively beta-sheet structure, as revealed by spectroscopic data, we conclude that this band is a cylindrical beta-pleated sheet crossing the membrane nearly perpendicularly to its plane. Another intriguing finding is a low-density area (about 70 A2) situated in the centre of the trimer.

Time-resolved low-dose microscopy of glutamine synthetase molecules.

Time sequences of low-exposure images from the enzyme molecules of glutamine synthetase have been recorded digitally using an on-line recording system. Processing the images results in a time sequence of averaged molecule images, which, in the very beginning, exhibit the molecule structure still undamaged by electron irradiation. Different sources of the noise which obscures structural details, such as shot noise, stain embedding and radiation damage, are investigated.

[On the reliable visualization of digital arteries as recorded by arteriography applying only local anesthesia and alcoholic drink (author's transl)]. / Zur sicheren Darstellung von Digitalarterien an Händen und Füssen in Lokalanästhesie nach oraler Alkoholgabe

Reliable visualization of arteries in hands, fingers, feet and toes largely depends on the tone of peripheral vessels. This can be lowered by general anesthesia but also under local anesthesia if local warming and oral Alcohol are added. Differential diagnosis between organic and functional disturbances of circulation is guaranteed in this way. Digital arteries can be well shown right down to the tips of fingers and toes.

[Percutaneous removal of a guide wire from the right ventricle and pulmonary artery (author's transl)]. / Perkutane Entfernung eines Führungsdrahtes aus dem rechten Ventrikel und der Arteria pulmonalis

Successful removal of an opaque guide-wire from the right ventricle and left pulmonary artery is reported. The wire was extracted into the right external iliac and common femoral vein and then removed by a venotomy. Percutaneous removal of embolised foreign bodies should be carried out as soon as possible. An attempt at percutaneous removal is to be preferred to a thoracotomy because of the considerably reduced risk.

[Digital-subtracted magnetic resonance (DSMR). A new procedure for improved imaging of vascular processes]. / Digital-Subtrahierte Magnetische Resonanz (DSMR). Ein neues Verfahren zur besseren Darstellung von Gefässprozessen.

Using varying echo-sequences, NMR studies of flow in vessels shows varying signal relationships which are caused by intermittent re-focussing of the elementary magnetic particles. By means of digital subtraction of the tomograms, this effect can be clearly shown. It has been demonstrated that this particular procedure can be used for improved visualisation of vessels and of abnormal vascular processes (thrombosis, tumours, aneurysms etc.).

[Early clinical experience with nuclear magnetic resonance (author's transl)]. / Erste klinische Erfahrungen mit der Kernspintomographie (KST).

Previous work on adults with carcinomas, benign polyps, postoperative changes or inflammatory or radiation induced swellings in the facial skeleton has shown that it is possible to demonstrate the local anatomy, and particularly the orbits and sinuses without subjecting the patients to radiation. Differentiation between fat, oedema and malignant tissue appears to be possible, as has been demonstrated by our early cases. Early attempts at examining the trunk could only be carried out in infants. These suggest that in the thorax and abdomen differentiation of anatomical structures is not possible. The value of nuclear magnetic resonance in clinical diagnosis is still uncertain. Its advantage depends on the ability to differentiate tissues because of their varying water content. It raises the possibility of differentiating soft tissues by a non-invasive method and without using radiation. Further investigations are necessary in order to evaluate the clinical usefulness of the new technique. The physical basis of the method, compared with conventional radiology, permits only guarded optimism.

[Nuclear magnetic resonance tomography of the breast: diagnosis, differential diagnosis, problems and possible solutions. II: Diagnosis]. / Kernspintomographie der Mamma: Diagnose, Differentialdiagnose, Probleme und Lösungsmöglichkeiten. Teil II: Diagnostik.

Eighty-five MR examinations were carried out on both breasts of 72 patients. A special surface coil was used. The results were compared with the findings of mammography and with the post-operative findings. There were 16 fibrocystic mastopathies, seven isolated cysts, 22 fibro-adenomas and 25 carcinomas. Differentiation between fibro-adenomas and carcinomas is only possible on the basis of morphological criteria. Cysts and fibrocystic mastopathies can be identified with certainty. Typical patterns of the various pathological conditions are described, but these will have to be confirmed by the study of a larger number of patients, in order to make them statistically significant. The advantage of MR consists in the simultaneous demonstration of the thoracic wall and the axilla.

[Nuclear resonance tomography of the breast--diagnosis, differential diagnosis, problems and solutions. I. Study procedures]. / Die Kernspintomographie der Mamma--Diagnose, Differentialdiagnose, Probleme und Lösungsmöglichkeiten. Teil I: Untersuchungsverfahren.

The experience gained from performing nuclear resonance tomography on the breast, using a special surface coil, is described. The technical problems, causes of artefacts and the advantages of tomography in three planes are discussed. The procedure is slow. Images obtained by various repetition and echo delay times in several planes are illustrated. Problems in quantifying T1 and T2 images and methods for improving the technique are described in detail. During the course of 85 examinations on 72 patients, it has been possible to achieve technical improvements.

[The accuracy of surface kymography following myocardial infarcts, with special reference of cardiac aneurysms (author's transl)]. / Sicherheit der Flächenkymographie nach Myokardinfarkt unter besonderer Berücksichtigung der Herzwandaneurysmen

Surface kymography in three planes were performed in 180 patients following myocardial infarcts, and these were compared with the results of coronary angiography and selective laevocardiography. Kymography performed for the diagnosis of cardiac aneurysms and myocardial scars is relatively accurate (53%), as shown by a comparison with the laevocardiograms. Of the aneurysms demonstrated by laevocardiography in the left ventricle (31), it was possible to show 22 (71%) kymographically. In order to achieve these results, it is necessary to examine at least three marginal contours of the left ventricle by kymography (left heart border, anterior and posterior wall). The routine use of kymography before employing invasive techniques provides useful information regarding the optimal plane of the laevocardiogram. Furthermore, it indicates the presence of myocardial disease and the need for further investigation.

[Changes in serum osmolarity after high contrast doses during angiography]. / Verhalten der Serumosmolarität bei hohen Kontrastmitteldosen im Rahmen der Angiographie

Analysis of changes in osmolarity of the serum after various doses of hypertonic radiographic contrast media, following a single injection, showed an initial rise of about 35 m/mosm/1, followed by a rapid fall in osmolarity with a subsequent short hypo-osmolar phase. With repeated injections, similar changes are found if the intervals between the injections are long enough. Following repeated injections over a short interval, there may be a more prolonged phase of hyperosmolarity. In this phase of delayed dehydration, there may be clinical complications. Possible forms of treatment are discussed.

[Radiation exposure of the population from examination of the thoracic organs]. / Die Strahlenexposition der Bevölkerung durch Untersuchung der Thoraxorgane.

The radiographic examination of the lung is still the most frequently carried out radiodiagnostic procedure, and--as explained--will remain so in future, too. The article reports on the significance that the examination of the lung has for the x-ray exposure of the population, the body surface dose, the bone marrow dose, the effective dose equivalent, and the energy absorbed being the measure for the exposure. The considerable variation of the absorbed doses dependent on the different x-ray systems and the effect of new techniques (large screen intensifiers) are described.

[Post-traumatic findings in the cerebral arteries in the neck (author's transl)]. / Posttraumatische Befunde an Hirnarterien im Halsbereich.

Starting from the observation of a post-traumatic thrombosis in the cervical portion of the carotid artery, with two subsequent similar findings, it is shown that angiography is of special importance in assessing these cases. Investigation of the cervical region of this artery should be considered in all cases of skull and cerebral trauma. On the other hand, the cases described by Sullivan show that the presence of a carotid lesion must be considered in all multiple injuries, just as injuries to vessels and organs must be excluded in patients with intracranial haematomas. Consultation between physician and radiologist is necessary for all injured patients in order not to omit any important steps during angiography.

[Venous and arterial digitalised video subtraction angiography (DVSA). Initial experience with 120 examinations (author's transl)]. / Transvenöse und arterielle digitale Videosubtraktionsangiographie (DVSA). Erste Erfahrungen nach 120 Patientenuntersuchungen.

Digitalised video subtraction angiography permits the demonstration of arteries in the trunk by means of intravenous injection. Initial experience with 120 examinations has demonstrated its usefulness for showing the arteries in the neck, the aorta, the renal arteries, pelvic arteries and arteries in the thigh in between 80 and 90% of cases. Use of the technique during arterial arteriography avoids the need for photographic subtraction and permits a reduction of contrast volume and flow rate. Further clinical experience will be necessary in order to determine the value of the technique.

[Catheter dilatation of arterial stenoses of supra-aortic vessels and late results]. / Katheterdilatation der arteriellen Stenosen supraaortaler Gefässe und Spätergebnisse.

Arterial stenoses of supra-aortic vessels, particularly of the subclavian and vertebral arteries, can be successfully treated by percutaneous transluminal angioplasty (PTA). In 125 patients primary success was achieved in 93% by PTA; 84 patients have been followed up for an average of 46 months and a clinical cure rate of 98.8% has been achieved. Apart from one re-stenosis all patients were symptom free and no other re-stenoses could be demonstrated. PTA of occlusions of supra-aortic vessels has less chances of success.

[Technic and results of computed tomography of the base of the nose and orbit with multiplanar reconstructions]. / Technik und Ergebnis der Computertomographie der Rhinobasis und der Orbita mit multiplanaren Rekonstruktionen.

The additional use of a 3-D display programme provides valuable information in cases of trauma to the mid-face and tumours of the bony orbits. The computer programme provides important additional information for the radiologist and, in future, will influence treatment significantly.

[The long-term results after Hydrolyser-supported angioplasty--a prospective study]. / Langzeit-Ergebnisse nach Hydrolyser-unterstützter Angioplastie--eine prospektive studie.

PURPOSE: Data of a three-year follow-up after mechanical thrombolysis with the Hydrolyser catheter were evaluated. Patients have otherwise been treated by local thrombolysis. METHOD: 35 patients were treated by thrombolysis, balloon angioplasty, aspiration, local thrombolysis, and stent placement, if necessary. Morphological results following Hydrolyser treatment and additional treatment were evaluated. RESULTS: Following Hydrolyser treatment a significant reduction of the degree and length of the occlusion was observed. Primary clinical success was 80%. Patency rate after 3 years was 0.5. 23% of all patients died in the follow-up period. CONCLUSION: The Hydrolyser treatment is a relevant alternative to local thrombolysis. This method reduces the time of treatment. The authors favor the lateral opening of the catheter to remove mural thrombus.

[The reduction of the extent of vascular lesions during angioplasty by the use of a sheath]. / Reduktion des Ausmasses von Gefässläsionen im Rahmen der Angioplastie bei Gebrauch einer Schleuse.

PURPOSE: To document the protection of the vessel using an introducer sheath. MATERIAL AND METHODS: In eleven in situ specimens we compared in the inguinal vessel the macroscopic and histologic trauma to the vascular wall during antegrade percutaneous balloon dilatation either without or with a sheath. RESULTS: Significant differences we observed regarding both the puncture site configuration and the puncture hole border, which were evaluated macroscopically. During the histological assessment we found only small intimal trauma in the puncture track in the group where a sheath had been used. Severe intimal damages and the media showed tears if no sheath had been used (100/36% vs. 0/64%). CONCLUSION: It is evident that using a sheath during angioplasty reduces the risk of intimal damage and, consequently, of complications such as recurrent haematoma, stenosis at the puncture site or formation of aneurysms due to the puncture.

[Importance of MR tomography for the diagnosis of bone marrow diseases in childhood]. / Bedeutung der Kernspintomographie für die Diagnostik von Knochenmarkserkrankungen im Kindesalter.

As a diagnostic and follow-up method of bone marrow diseases in children, magnetic resonance imaging (MRI) possesses special importance. It is characterised by high sensitivity in detecting bone marrow lesions, high soft tissue--bone tissue contrast, sharp demarcation of intraosseous lesions and visualisation of vascular structures without application of contrast medium. Thus it is able above all to take on the findings of radionuclide bone scanning, computed tomography and angiography. In the detection of pathophysiological alterations of the corticalis and of calcifications it is less reliable than x-ray images and CT.