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Biomedical subjects

E P Strecker

Publications and source records attributed to E P Strecker.

At least 37 records · Page 2Linked to original sources

[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↗

[Experimental research with a new percutaneously insertable and expandable vascular prosthesis].

Restenosis and occlusion are the most common reasons why transluminal balloon angioplasty may fail to provide long-term benefit. To prevent restenosis and occlusion of diseased arteries after angioplasty an arterial endoprosthesis has been developed which is positioned to the balloon of an angioplasty catheter and which consists of a stainless steel pliable and elastic tube. With the inflation of the balloon the endoprosthesis will dilate and give the arterial wall a new mechanical support. This new device has been implanted in 12 experimental dogs in arteries of different size and lumen. The longest patency rate of nine months was observed with the completely developed method.

Angioplasty, Balloon↗

NMR tomography for the visualization of the diffusion of Gd-DTPA in agar-gel and in brain tissue--in vitro studies.

Serial magnetic resonance images of a diffusion model and of brain specimens have been performed to study the diffusion behavior of a paramagnetic complex (Gd-DTPA). The model consisted of solidified agar gel with layered Gd-DTPA solution on top of the gel. Corresponding studies have been performed with the brain specimen to visualize the penetration of the marker through the extracellular space into the brain tissue. Diffusion coefficients for the agar gel and the brain tissue model have been calculated. Magnetic resonance tomography proves to be a promising method for the study of complicated diffusion processes of paramagnetic complexes in biological tissue.

Agar↗

Cerebrospinal fluid pressure alterations in experimental communicating hydrocephalus. Response of cerebrospinal fluid pressure to increase in arterial carbon dioxide tension.

The response of cerebrospinal fluid (CFS) pressure to increased arterial carbon dioxide tension (PCO2) was evaluated in 5 control animals and 7 animals with experimentally induced communicating hydrocephalus. The CSF pressure in control dogs increased moderately in response to PCO2; in dogs with hydrocephalus, an increase in PCO2 produced a pronounced increase in CSF pressure accompanied by a simultaneous decrease in cerebral perfusion pressure. Progression of hydrocephalus can be explained by increased intracranial pressure, periventricular edema and cerebral ischemia.

Animals↗

Influence of NMR measuring sequences and gradient variation on signals from flowing systems. Magnetic resonance tomography on experimental models.

The influence of flow on MR tomography images and signal intensities has been studied using experimental model tubes and an aqueous NiCl2 solution having the same relaxation time as human blood. We applied the inversion recovery (IR) and the spin-echo (SE) sequence on a .15T MR tomography system. The influence of RF pulse distance (tau) in the IR and SE experiment as well as the influence of magnetic z-gradient strength on the flow images has been investigated. IR images revealed that signals from flowing systems recover more rapidly due to influx of non-inverted longitudinal magnetization into the scan slice. SE images in presence of flow are characterized by signal intensity loss with increasing time caused by the outflow and dephasing of transverse magnetization. With increasing strength of the z-gradient, the MR signals of flowing fluids decrease drastically. Thus for detection of flow, all the above mentioned parameters are of importance.

Blood↗

[Microangiographic examinations of different human tumors after transplantation to thymus aplastic nude mice].

Ten different human tumors (two soft tissue sarcomas, seven adenocarcinomas of the colon and stomach and, one squamous cell carcinoma of the lung) were implanted s.c. in thymus-aplastic mice and retransplanted over several generations. In 40 animals, the tumors were studied by microangiography and microscopy and classified according to angiographic tumor criteria. Tumor transplants always revealed similar angiographic patterns. The microscopic results presented a good correlation with the roentgenologic findings. The microstructure of the tumor vessels and lacunes are analyzed and discussed. The nude mice model is well suitable for the research of human tumors.

Angiography↗

[Experimentally induced tumors used for angiographic estimation of embolisation and cytostatic treatment (author's transl)].

In 12 rats tumors have been induced chemically by intraperitoneal application of dimethylnitrosamine. This method is simple and reliable and the effect of tumor embolisation can be followed easily. Thymus aplastic nude mice with transplanted human tumors deserve strict care. Tumor microangiograms of 48 animals demonstrate a close similarity with angiograms of corresponding human tumors. The vascular pattern does not alterate after several transplantations, after cytostatic therapy a slight hypervascularisation develops.

Angiography↗

[Clinical experiences in rapid infusion of jotroxamide in cholegraphie (author's transl)].

Jotroxamid has been infused intravenously in 60 patients within 10 minutes for cholegraphy. At the evaluation, contrast medium side effects, heterotopie excretion, quality of contrast and length of examination time have been considered. Reactions to the contrast medium were low compared with the results of other authors, an increase of cases with roentgenographie demonstrable heterotopic excretion could not be observed. Opacification of the biliary duct system was except in 2 cases very good. The total examination time was compared with the conventional infusion rate 30 minutes less.

Biliary Tract Diseases↗

Indications and use of abdominal angiography in trauma.

A series of 148 angiographic examinations in patients with blunt abdominal trauma have been reviewed. The major indications for arteriography were: (1) manifestations of shock in conjunction with clinical signs of abdominal injury; (2) the necessity for differentiation of multiple abdominal injuries; and (3) clinical signs of delayed rupture. Few false positive or false negative results were noted. The typical angiographic findings are discussed.

Abdominal Injuries↗

[Indications and value of treatment by catheter occlusion (author's transl)].

The value of the catheter occlusion therapy is analyzed in 92 cases retrospectively, and the indication, and complication risk of these procedures are considered. In the following vessel areas occlusion with different methods have been performed with decreasing frequency; kidneys, pelvis, legs, gastrointestinal tract, external carotid and internal carotid artery. Serious complications have been observed in therapeutic investigations at the head, especially in occlusions of the external carotid artery. In this group embolisation therapy should be performed with strict indication only.

Adrenal Gland Neoplasms↗

[The effect of selective autoperfusion through an extracorporeal circulation on the formation of arterial collaterals. Animal experimental results (author's transl)].

In 11 mongrel dogs (10-15 kg) with ligated superficial femoral arteries the formation of collaterals induced by increased arterial pressure with an extracorporal circulation was studied. In general anesthesia a teflon tube was inserted into one deep femoral artery. The other end of this tube war introduced through the right carotid artery into the thoracic aorta and arterial blood was drawn by a peristaltic tube pump from the aorta to the femoral artery. Different arterial pressures created by the pump were used to perfuse this hind limb. After 40 minutes perfusion time with 200 mmHG pressure, there was marked increase of collateralization by the deep femoral artery. At the contralateral non treated side, only minimal development of collaterals was visualized. These angiograms demonstrate that collaterals are opened by increased pressure within a short time interval The experimental model might have clinical implisations and accelerate collateral formation in non-surgical treatment of arterial occlusive disease.

Animals↗

Inhalation bronchography using powdered calcium ioglycamic acid.

In 16 baboons, reproducible bronchograms could be achieved by inhalation of 400--800 mg of powdered calcium ioglycamic acid. Anesthesia, tracheal intubation, or premedication were not necessary. In patients and volunteers, the inhalation of the contrast medium dust caused strong cough. Local anesthesia allowed inhalation for about 10 minutes, which resulted in successful demonstration of the pharynx, larynx, and trachea with bifurcation. Lobular and segmental bronchi were demonstrated only after a longer inhalation time. The contrast medium was completely eliminated and did not cause any recognizable adverse reaction. Nonspecific inflammatory reaction of the bronchial mucosa was seen microscopically in baboons.

Adult↗