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Biomedical subjects

D Papakostopoulos

Publications and source records attributed to D Papakostopoulos.

43 records · Page 3Linked to original sources
PubMed1973

The contingent negative variation and the excitability of the spinal monosynaptic reflex.

A method is described which permits simultaneous measurement of changes in slow electroencephalographic potentials (Contingent Negative Variation-CNV) and the excitability of the spinal monosynaptic arc (H reflex) during the foreperiod of a simple reaction time experiment. Data from 11 normal subjects show that during the development of the CNV there is an augmentation of the amplitude of the H-reflex. It is suggested that the two phenomena are controlled by a common subcortical structure.

Acoustic Stimulation↗
PubMedDate not supplied

The electroretinogram in multiple sclerosis and demyelinating optic neuritis.

The electroretinogram (ERG) to flashes of white light presented under photopic conditions and the pattern reversal visual evoked potentials (PR-VEPs) from both eyes were recorded from 14 patients with multiple sclerosis (MS) with monocular demyelinating optic neuritis (DON) and from 11 patients soon after presenting with monocular demyelinating optic neuritis alone. Fifteen and 10 normal subjects, matched for age and sex, were used as controls for each group of patients respectively. In the DON group of patients and controls the flicker following ERG (FF-ERG) to white flashes of light at 40 Hz was also recorded. Skin electrodes and averaging procedures were used for all the recordings. The PR-VEP elicited with stimulation of the affected eye was absent or abnormally delayed, and the amplitude of the 'b' wave of ERG of the affected eye was diminished in all patients. The 'b' wave latency, however, was similar in both affected and non-affected eyes and the controls. There was no difference in 'a' wave amplitude and latency between eyes of patients and normal subjects. The FF-ERG in 8 out of 10 patients with satisfactory recordings was diminished in the affected eye. These results provide neurophysiological evidence that retinal damage is not due to loss of myelin but is an early feature of demyelinating optic neuritis. This damage preferentially affects the retinal elements associated with the generation of the 'b' wave of the ERG, probably the glial cells of Müller.

Demyelinating Diseases↗
PubMedDate not supplied

Changes in the pattern reversal visual evoked potentials in myasthenia gravis.

To investigate the possibility of impaired cholinergic transmission in the Central Nervous System (CNS) in patients with Myasthenia Gravis (MG), the PR-VEPs in 11 newly diagnosed MG patients before and after pyridostigmine treatment compared to those recorded from 10 normal subjects tested in two different occasions one month apart. All patients, (7 female and 4 male) had a good response to treatment. The amplitude of the P100 of the PR-VEPs of the MG patients before and after treatment was significantly lower than those recorded from the normal control subjects and the latency significantly longer. In the patient group the amplitude of the P100 improved significantly after treatment. These results provide neurophysiological evidence of impaired cholinergic transmission in the CNS in patients with MG and suggest that PR-VEPs offer an easily applicable non-invasive method to study the central effects of MG and possibly a procedure to monitor the effectiveness of pyridostigmine treatment.

Adolescent↗