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Biomedical subjects

U Raff

Publications and source records attributed to U Raff.

31 records · Page 2Linked to original sources
PubMed1977

[The influence of antiarrhythmic drugs on the exercise-ecg (author's transl)].

The influence of five most common antiarrhythmic drugs on exercise-electrocadiogram was investigated: prajmaliumbitartrat, quinidinbisulfate, diphenylhydantoine, propranolol, and verapamil. All exercise-tests were performed in eight healthy males. During exercise and the subsequent resting period, the changes in the following parameters were analysed: blood pressure, heart rate, P-Q-time, Q-T-time, and the formal course of the Ecg as well as individual reactions. None of the drugs produced a pathological ECG. As for the analysed parameters, diphenylhydantoine was entirely neutral, whereas propranolol caused the most significant changes. Propranolol lowered heart rate by more than 20% and blood pressure by 10%. Verapamil had a less pronounced effect on diastolic blood pressure and heart rate. Prajmaliumbitartrat and quinidine had no definite effect during exercise and resting period.

Adult↗
PubMedDate not supplied

Lesion detection in radiologic images using an autoassociative paradigm: preliminary results.

An area of artificial intelligence that has gained recent attention is the neural network approach to pattern recognition and classification. The use of neural networks in radiologic lesion detection is explored by employing what is known in the literature as the "novelty filter." This filter uses a linear algebraic model, whereupon in neural network terms, images of normal patterns become "training vectors" and are stored as columns of a matrix. An image of an abnormal pattern is introduced and the abnormality or the "novelty" is extracted. A noniterative technique has been applied. In a preliminary experiment, autoassociative recall was tested using alphabetic characters as training vectors. The second experiment used sections of transverse magnetic resonance (MR) images (TR = 3000 ms, TE = 40 ms) of normal patients as the training vectors. A section of a transverse MR brain image with multiple sclerosis lesions was introduced to the filter and the abnormalities were extracted. In conclusion, a neural network based lesion detector may have great promise in medical pattern recognition.

Humans↗
PubMedDate not supplied

Automated lesion detection and lesion quantitation in MR images using autoassociative memory.

Previous efforts concerning lesion extraction in radiologic images indicated that autoassociative memory models can be a valuable tool in automated lesion detection. Preliminary results are expanded to resolve the technical problems of image registration and magnification. Instead of operating on selected portions of the MR images, each entire image matrix is operated upon as image vector comprising all stacked columns of the matrix. Spin density weighted images (TR = 3000 ms and TE = 40 ms) of 42 normal subjects were remapped and standardized with respect to location and magnification. All image vectors were orthonormalized to span a linear manifold. Standardized abnormal image vectors were then tested by the stored autoassociative memory and the abnormalities (novelties) were extracted by application of an autocorrelation matrix to the input vector. The autocorrelation matrix is computed using image vectors from normal subjects. The lesions (multiple sclerosis and tumors) are then identified as the orthogonal component to the linear manifold spanned by the basis vectors of the normal brain scans. Lesion extraction has been achieved with the intention of quantitating and staging diseased parenchyma after automated edge detection.

Algorithms↗
PubMedDate not supplied

CA 125 as an indicator of pleural metastases in breast cancer patients.

In this study we analyzed the role of CA 125 serum levels in the diagnosis and follow-up of pleural metastases in breast cancer patients. CA 125 serum levels were measured in patients with lung and/or pleural metastases: a) at the time of detection of the metastases, b) 3 months thereafter during therapy and c) before and after drainage of pleural effusions. In all patients occurrence of metastases at other localisations was excluded. For CA 125 measurements ELISA sandwich assays were performed. In 76 patients with metastases CA 125 levels were elevated in 8% of patients with lung metastases, in 89% with pleural metastases and in 94% with-both sites of metastases. In patients with lung metastases, the CA 125 concentrations did not follow the clinical course of disease, while in patients with pleural metastases CA 125 levels followed the course of disease in 25 of 25 progressions and in 5 of 6 remissions. After the puncture of pleural effusions CA 125 levels decreased in 7 of 14 patients and remained stable in the other 7 patients.

Biomarkers, Tumor↗