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Biomedical subjects

E Zeitler

Publications and source records attributed to E Zeitler.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Early and late results of PTA in relation to the patient's age].

506 cases of percutaneous transluminal angioplasty performed between 1983 and 1988 in the iliac, femoropopliteal and crural segments were analyzed with special consideration of the patients' age. The early results were significantly worse only in the age group over 70. The late results were evaluated by the life table method. Relapses within the first 6 months occurred in 13.8% of the patients over 60 and in 8.2% of the younger age group (under 60). After 12 months, however, no significant difference was observed between the two age groups. The rate of complications (overall value 7.9%) was twice as high in the geriatric age group than among the younger patients. Type and extent of the occlusion, clinical stage and run-off conditions determine the early and late results.

Age Factors↗
PubMed1989

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.

Bacterial Outer Membrane Proteins↗
PubMed1989

Peripheral percutaneous transluminal laser angioplasty in humans: in vitro investigations and clinical results with a novel laser catheter system.

Percutaneous transluminal laser angioplasty has become an accepted method of treatment of peripheral arterial occlusive disease. To minimize the risk of arterial wall perforation during laser angioplasty, a novel laser catheter system was developed. In 113 obliterated postmortem human arteries the perforation rate was 0.9%. The mean degree of stenosis was reduced from 89 +/- 9% before, to 53 +/- 11% after laser irradiation. Clinical Nd:YAG laser angioplasty was performed in 19 patients suffering from peripheral arterial occlusive disease. The Fontaine stage improved in 16 patients; in no case did it deteriorate. The mean degree of stenosis was reduced by laser angioplasty from 91 +/- 12% to 31 +/- 19%. A further reduction down to 13 +/- 18% was achieved by subsequent percutaneous transluminal balloon angioplasty. The systolic Doppler ankle-arm pressure gradient was improved from 0.58 +/- 0.26 to 0.89 +/- 0.25. In 7 patients microembolisms were detectable on the final angiogram. There was no acute reocclusion and no perforation. Within a follow-up period of 12 months, four restenoses were diagnosed by digital subtraction angiography. On average, the Doppler index was 0.75 +/- 0.32.

Angioplasty, Balloon↗
PubMed1989

The value of angiography in cerebrovascular disease.

The expanding availability of digital subtraction angiography has essentially contributed in lowering the risks in the use of angiography of the cerebral arteries. The best results in imaging the cerebral artery are achieved by conventional subtraction angiography after selective catheterisation. This is, however, only important for diagnosis in intracerebral pathological changes distal of the Circulus Willisi or in connection with preoperative interventional radiological treatment. Pre-clinical diagnosis of patients with cerebrovascular occlusive disease as well as clinical diagnosis with Doppler and B-scan US sonography can be optimally complemented by DSA using 4-5 French catheters entered in the thoracic ascending aorta. Using this technique, the sensitivity and specificity with an image-matrix of 512 is diagnostically adequate and includes an only limited examination risk. Complication with lasting neurological defects will be least observed after intravenous pre-atrial application of contrast media and most after selective angiography of the carotid artery. Here the extent of the multiple arteriosclerotic obliteration is of essential importance. The quality of interpretation of the diagnostic findings essentially depends on indications not only about the grade of obliteration but also on the morphological details. At present DSA with application of contrast media into the thoracic ascending aorta in combination with the duplex-scan method represent the optimum for the diagnosis of cerebrovascular disease. In spite of lower specificity intravenous application of contrast media has to be preferred for post-operative controls and controls of progressing disease with "screening".

Carotid Arteries↗
PubMed1989

MR imaging of the breast: fast imaging sequences with and without Gd-DTPA. Preliminary observations.

Of a total of 191 magnetic resonance breast studies performed since March 1984, 82 were performed with gradient-echo fast low-angle shot (FLASH) sequences and fast imaging with steady precession (FISP). These techniques permit imaging of thin and contiguous sections, resulting in high resolution of the parenchymal structure. Intravenous injection of 0.1 mmol/kg of gadolinium diethylenetriamine-pentaacetic acid dimeglumine (50% of the dose used in spin-echo sequences) aided in detection of carcinomas as small as 3 mm in dense breast tissue. In 25 patients, dynamic studies were performed at short intervals after the injection of contrast medium in an attempt to differentiate more reliably between breast tissue types. All six malignant tumors found in these 25 patients showed enhancement characterized by a sudden increase in signal intensity on the order of 100% within the first 2 minutes after injection and a much slighter increase thereafter. Sixteen benign lesions showed a substantially different pattern of enhancement. Further studies are required to confirm these findings.

Breast↗
PubMed1989

[Results of percutaneous transluminal angioplasty].

Percutaneous transluminal angioplasty (PTA) can be subdivided into three epochs: 1. from its inception by Dotter and Judkins up to the first coronary artery stenosis dilatation with the Grüntzig balloon catheter system; 2. from the introduction of coronary stenosis dilatation by Grüntzig up to its unequivocal acceptance; 3. the period of influence of low-risk coronary dilatation on peripheral angioplasty and the search for techniques to compliment or obviate the need for balloon dilatation. The Grüntzig double-lumen balloon catheter system contributed to the lower rate of complications and higher success rate. The clinical acceptance appeared greater for the coronary arteries since, in contrast to the peripheral vascular system, the indication for treatment is established by the physician performing the dilatation. PTA implies percutaneous puncture of a vessel with Seldinger technique and introduction of devices such as guidewires, Dotter or Grüntzig catheters among others, catheters with fiberglass for laser conduction and instruments for fractionating, drilling and cutting. The goal of PTA is to completely or partially eliminate, without surgery, intraluminal vascular narrowing in the presence of peripheral arterial disease in stage II, III or IV. Prerequisite to the use of PTA are: 1. adequate fluoroscopic and angiographic facilities; 2. adequate instrumentation; 3. experience with at least 200 procedures; 4. knowledge of the pathophysiology and adjunctive treatment; 5. knowledge of the treatment of complications; 6. cooperation with a vascular surgery service. A number of factors may influence the results of treatment. Adjunctive medical treatment: the use of platelet aggregation inhibitors and heparin influences the rate of early rethrombosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

[Angioradiology in geriatric patients].

The number of geriatric patients has increased in the last decade, as shown in diagnostic angiography and angioplasty. Therefore, the radiologist must be prepared for technical problems. Elderly patients need special premedication, care and also more time for each diagnostic and interventional procedure. In these patients, in several situations DSA can be done more efficiently as an inpatient procedure and not on an outpatient situation. Angioplasty of iliac and femoropopliteal injuries in this population is not only a means of treating claudicatio without high risk, but of also preventing amputation of the leg. Also, even though there are few long-term results, it is of interest that PTA can be done again at the same location. Therefore, early DSA is an important method of reducing the amount of high-risk surgery required. The radiologist must therefore realize that geriatric patients require special management and that excellent interdisciplinary cooperation is needed.

Aged↗
PubMed1988

[Diagnosis of kidney transplant rejection. The value of scintigraphy, sonography and NMR tomography].

Scintigraphy, ultrasound and magnetic resonance imaging were undertaken within three days on 73 patients who had had renal transplantation. Clinical and histological criteria were used to assess the ability of diagnosing rejection of the transplant. In all instances of rejection cortex-marrow differentiation was absent on magnetic resonance (MR) imaging; there were no false-negative results. Sensitivity as to rejection was 100% for MR imaging, 58% for scintigraphy and 32% for ultrasound. It may be possible to distinguish between cytomegalovirus infection and rejection reaction by MR imaging. It is concluded that MR imaging is the most reliable method for predicting rejection reactions, while ultrasound and scintigraphy are valuable for making other diagnostic decisions.

Evaluation Studies as Topic↗
PubMed1988

[Percutaneously implantable balloon-inflatable vascular prostheses. Initial clinical results].

Restenosis and occlusion of atherosclerotic arteries are prevented by a newly developed arterial prosthesis consisting of a pliable and elastic wire mesh tube positioned to the balloon of an angioplasty catheter. As the balloon is inflated the prosthesis dilates and provides the arterial wall with a new mechanical support. This new device was successfully implanted in ten patients having an iliac artery stenosis and improved the therapeutic result of the preceding angioplasty. There were no complications.

Aged↗
PubMed1988

[Percutaneous peripheral laser angioplasty: initial clinical results].

Laser angioplasty has developed as a new method for the treatment of peripheral arterial occlusive disease. In 19 patients with high grade stenoses or obstructions of the superficial femoral, popliteal or posterior tibial arteries (Fontaine stage IIa-IV) percutaneous transluminal laser angioplasty was performed using a novel laser catheter system. The laser catheter itself is made of polyethylene. Its distal tip is formed ovally and marked X-ray densely. A silica fiber (core diameter 0.6 mm) for delivering the laser energy is inserted into the laser catheter. Through a sheath with hemostatic valve, laser catheter and silica fiber are introduced into the artery and then advanced to the stenosis over a guide wire. During laser angioplasty, laser catheter and silica fiber are rotated around the guide wire. We use a cw-Nd: YAG laser with a wavelength of 1064 nm. The mean degree of stenosis decreased from 92 +/- 12% before to 31 +/- 19% after laser angioplasty. By conventional balloon angioplasty a further reduction of the degree of stenosis down to 15 +/- 20% was achieved. The mean systolic Doppler ankle-arm pressure ratio improved from 0.56 +/- 0.25 before laser angioplasty to 0.89 +/- 0.24 after combined laser and balloon angioplasty. In seven patients, clinically non-significant distal embolization occurred. In no patient there was a perforation of the arterial wall. Up to now, digital subtraction angiography 3 months after laser angioplasty has been performed in five patients and showed patency of all lesions. The mean systolic Doppler ankle-arm pressure ratio was 0.84 +/- 0.20.

Aged↗