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Biomedical subjects

J Balík

Publications and source records attributed to J Balík.

At least 19 recordsLinked to original sources
PubMed1983

Changes in electroretinogram and serum potassium during L-DOPA treatment in parkinsonism.

The relationship of L-DOPA plasma level, parameters of ERG and severity of extrapyramidal symptoms after a single dose of L-DOPA was investigated in 11 patients suffering from parkinsonism of idiopathic or arteriosclerotic origin. After a drug-free night, each patient received his/her usual morning dose of L-DOPA. In the subsequent 3 h, the ERG recordings, blood levels and clinical ratings of extrapyramidal symptoms significantly dropped after a delay of 60 min in relation to the occurrence of the peak plasma L DOPA level. The initial "b" wave amplitudes as well as initial serum potassium values were abnormally high. There was a statistically significant correlation between the decrease of "b" wave amplitude (delta "b") and the potassium "normalization index" (i.e. the ratio between the observed decrease of serum potassium and the pretreatment difference from the middle normal potassium value). A definite interpretation of the data cannot be provided until more knowledge about the origin of "b" wave of ERG is available. It can be concluded tentatively that dopaminergic processes influence electrophysiological reactivity of the retina.

Aged↗
PubMed1978

Possible indication of dopaminergic blockade in man by electroretinography.

In view of the finding that dopamine is the principle neurotransmitter in the retina, an attempt was made to demonstrate dopaminergic receptor blockade by means of electroretinography. In an open experimental setting, the effect of 50 mg thioridazine was compared with that of placebo in 2 groups of 10 normal volunteers. In the placebo group, the post-drug scotopic electroretinogram (ERG) was not significantly different from the pre-drug ERG, while in the thioridazine group, the post-drug scotopic ERG showed prolongation of 'a' wave latency time, prolongation of 'b' wave evolution time, and diminution of 'b' wave amplitude.

Action Potentials↗
PubMed1975

Incipient atrophy of cornea. Experimental study.

The essence of the process in which the corneal tissue disappears in atrophy of the eye has not yet been studied. The authors of this investigation studied the changes in cornea as they developed after a gross perforating injury to the eye in rabbit. They found that the diameter of the cornea had grown smaller by 2 mm and its radius by 0.5 mm. The tensile strength of the cornea had decreased and hydration increased. Histologically there were but little changes and histochemically a decreased amount of acid mucopolysaccharides was ascertained in the corneal stroma. Incorporation of radioactive sulphate (Na2-35SO4) in vivo disclosed decreased biosynthesis of glycosaminoglycans. Clinically, even though the eye ball atrophied, complete atrophy with flattening and complete diminution, as in the human eye, never developed. The question arises whether the six-months period was sufficient for rabbit cornea to develop clinically similar atrophy as in human cornea or whether the clinical features are principally different in the two species. Foci of ossification, as found in atrophic eye balls, which are known to develop after a long time, would be evidence of the second alternative.

Animals↗