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Biomedical subjects

A Scheffler

Publications and source records attributed to A Scheffler.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Acral skin circulation following intra-arterial infusion of vasodilating substances in patients with intermittent claudication].

The value of vasodilator drugs for the conservative treatment of peripheral arterial occlusive disease is widely questioned because clinical and experimental studies have shown paradoxical redistribution phenomena of blood flow in disfavour of an already ischemic peripheral circulation. This paper deals with acute effects of intraarterially infused prostaglandin E1 and buflomedil on the overall foot sole perfusion as well as its distribution patterns. Measurements were performed in patients with sufficiently compensated obstructions of the superficial femoral artery by means of dynamic fluorescein angiography. After i.a. infusion in general an increase of the total blood supply to the feet was found. However, in response to this common vasodilator effect in some patients apparently non-perfused circumscribed skin areas occurred which could never be observed under control conditions. With respect to these results the clinical value of vasodilator drugs as well as the meaning of such adverse redistribution phenomena are discussed from a pathophysiological and pharmacodynamical point of view. It is proposed that the therapeutical concept of pharmacological vasodilation should not be rejected in general. However, special attention should be paid to the development of steal effects.

Aged↗
PubMed1990

Morphological changes in cultures of hippocampus following prenatal irradiation in the rat.

The effect of prenatal irradiation was studied in organotypic cultures of hippocampus, prepared from newborn rats that had been exposed to whole-body irradiation of 1 Gy from a 60Co-source at day 13 of pregnancy. Light and electron microscopic observations showed remarkable damage to neuronal mitochondria accompanied by extensive swelling, vacuolation of the Golgi complex, and formation of multilamellar bodies and vesicles of the lysosomal type. In contrast to neuronal alterations, no delay in synaptogenesis or onset of myelination was observed based upon the absence of significant morphological changes in synapses and myelin sheaths. Using this tissue culture model it could be confirmed that prenatal exposure to irradiation, even at low doses, induces specific morphological changes in the brain.

Animals↗
PubMed1990

[Local lysis therapy in acute arterial thrombosis].

Acute thrombotic arterial occlusion is a complication of chronic vascular arterial disease. The arteriogram usually reveals a sudden occlusion and the collateral vessels. Treatment with low-dose fibrinolytic therapy is widely accepted. A combination of low-dose fibrinolysis, aspiration embolectomy and angioplasty yields the best primary success rate. In cases of sudden popliteal occlusion and dilating arteriopathy ultrasound sonography should be used to exclude the presence aneurysm which is a contraindication for fibrinolysis. There is a high risk of peripheral embolisation, in the presence of an aneurysm and this may cause severe deterioration of the arterial blood supply.

Angioplasty, Balloon↗
PubMed1990

A microcomputer system for evaluation of laser Doppler blood flux measurements.

Results of local skin perfusion measurements performed by laser-Doppler-fluxmetry (LDF) are generally expressed in terms of relative mean values of time constants of signal responses to various procedures. In addition, information is obtained from the frequency and amplitude of temporal signal variations. In this report, a microcomputer system designed for recording, storage, artifact elimination, evaluation, and documentation of LDF measurements will be described. This system consists of a desk-top computer with additional hardware necessary for digital data acquisition and acceleration of mathematical operations. A three-phase model defined by a control, a transient, and an effect interval was programmed in order to standardize calculations within the time domain. For spectral analysis of periodical signal fluctuations, an algorithm was implemented based on a Fast-Fourier-Transformation (FFT) in combination with an optional averaging of several spectra within the frequency domain. Clinical measurements performed on patients with peripheral arterial occlusive disease (PAOD) and healthy volunteers illustrate the features of the system.

Arterial Occlusive Diseases↗
PubMed1990

[Doppler ultrasound determination of pressure decrease in model peripheral arterial stenoses].

In a pulsatile in vitro flow model with mounted concentric peripheral arterial stenoses, we compared the mean trans-stenotic pressure difference between pre- and poststenotic segment with the Doppler-estimated mean pressure gradient calculated according to the simplified Bernoulli equation applied over an entire stroke cycle. A close linear correlation was found between Doppler-estimated and invasively measured pressure drop values: Y = 1.13X + 0.47 (r = 0.98, SEE = 1.4 mmHg, n = 16). The Doppler-derived overestimation of the invasively measured mean pressure-drop by an average of 16% (absolute values 2.2 +/- 1.7 mmHg) suggests that in this in vitro model a small part of the kinetic energy of the stenotic jet is recovered distal to the poststenotic turbulences. The difference between both methods is so little that the Doppler-estimated mean pressure drop is acceptable in concentric peripheral model arterial stenoses.

Arterial Occlusive Diseases↗
PubMed1986

[Fractionated afterloading irradiation as a new procedure for treating inoperable brain tumors].

A method is shown for fractionated afterloading therapy of inoperable cerebral tumors. A 3 mm thick, tube-form applicator of noble metal which is closed at the front side is implanted into the tumor by a stereotaxic technique and firmly screwed together with the osseous calotte. It remains there up to two weeks, giving full mobility to the patient. The afterloading therapy with a moving iridium source is performed one or two times per day with individual doses of 2 Gray. Thus, the chronological and--to a certain extent--also the spatial dose distribution is variable when applying this method.

Brachytherapy↗
PubMed1978

[The place of ultrasonic tomography in irradiation planning (author's transl)].

Therapy-planning frequently requires cross-section sketches of the body in correct scale. The use of anatomic-topographic standard cross sections can lead to considerable errors in the estimation of the actual position of the organs and yields no information on the extension of the pathological process. The kidney, the bladder and the prostate were used as examples to demonstrate the capacity of ultrasonic tomography to supply all information, including body contour, relevant to therapy planning, as long as no limits are set to the procedure, as in the thorax area. Ultrasonic tomography can supplement but not replace the radiological procedure in therapy-planning.

Humans↗