Biomedical subjects

W Scheidler

Publications and source records attributed to W Scheidler.

4 recordsLinked to original sources

PubMed1995

Vibrameter testing facilitates the diagnosis of uremic and alcoholic polyneuropathy.

The diagnostic sensitivity of Vibrameter and tuning fork examination towards uremic and alcoholic neuropathy was tested in 75 patients. In 40 uremic and 35 alcoholic patients, we compared the sensitivity of neurological examination, nerve conduction studies (NCS) and vibration thresholds assessed at the malleoli by means of Vibrameter and scaled tuning fork. Vibrameter results were correlated with NCS. Polyneuropathy was diagnosed in 52 patients, but in 16 patients diagnosis depended upon inclusion of Vibrameter testing in the examination protocol. In uremic patients, Vibrameter (47.5%) showed abnormalities as often as NCS (45%), and more often than clinical (32.5%) or tuning fork examination (2.5%). In alcoholic patients, Vibrameter revealed abnormalities more often (60%) than NCS (34.3%) or tuning fork (14.3%). Correlations between NCS and vibratory thresholds were low (-0.52 < or = Rs < or = -0.35). Vibrameter studies are far more sensitive than tuning fork tests. The technique complements NCS and refines the diagnosis of uremic and alcoholic neuropathies.

Adult↗

PubMed1994

[Cerebral sinus-venous thrombosis in protein S deficiency].

The coagulation inhibitor protein S is a cofactor for the protein C, which inactivates the factors V and VIII. In very rare cases a congenital or acquired protein S deficiency leads to a cerebral sinus or venous thrombosis. Guided by an own case report the other 15 cases of the literature are described. In most cases there was a thrombosis of the sinus sagittalis superior. Usually the active form, which is not bound to protein in plasma, is reduced. Women are more frequently involved than men. Partly there are additional risk factors to inheritance, such as pregnancy, puerperium or anticonceptive pills. In the acute stage the patients have to be treated with heparin, afterwards for a long time with dicumarol.

Adult↗

PubMed1987

Visual pattern recognition in humans. I. Evidence for adaptive filtering.

We have investigated how observers learn to classify compound Gabor signals as a function of their differentiating frequency components. Performance appears to be consistent with decision processes based upon the least squares minimum distance classifier (LSMDC) operating over a cartesian feature space consisting of the real (even) and imaginary (odd) components of the signals. The LSMDC model assumes observers form prototype signals, or adaptive filters, for each signal class in the learning phase, and classify as a function of their degree of match to each prototype. The underlying matching process can be modelled in terms of cross-correlation between prototype images and the input sample.

Form Perception↗

PubMed1986

Steady-state pattern VEP uncorrelated with suprathreshold contrast perception.

Campbell and Maffei (1970) reported a linear relationship between the logarithm of the grating pattern contrast and the amplitude of the visual evoked response (VEP). This enabled them to predict the pattern visibility by extrapolating to zero amplitude. By using a new digital fast sweep technique for acquiring and analysing steady state evoked potentials we show that, at clearly suprathreshold contrast levels, such a linear relationship only exists for certain spatial frequencies. In general, the VEP saturates with increasing contrast in a way that critically depends on stimulus spatial frequency. Such a dependency on spatial frequency is not obtained for suprathreshold contrast perception which is characterized by a remarkable contrast constancy. Thus the amplitude of the pattern VEP does not convey information about visual perception other than contrast detection thresholds.

Animals↗