Biomedical subjects

Z Grujic

Publications and source records attributed to Z Grujic.

3 recordsLinked to original sources

PubMed1998

Dopamine agonists reorient visual exploration away from the neglected hemispace.

OBJECTIVE: To study the effects of bromocriptine, a dopamine agonist, on visual search. BACKGROUND: The anatomic substrate of spatial attention takes the form of a distributed network with interconnected cortical (frontal, parietal, and cingulate) and subcortical (striatal and thalamic) components. Dopamine appears to exert a modulatory effect on the function of this network. METHODS: Seven consecutive right-handed subjects with right-sided cerebral lesions were studied using a computerized target search paradigm. Eye movements were recorded. RESULTS: Bromocriptine caused the subjects to spend more time exploring the ipsilesional hemispace and therefore increased the relative neglect of the contralesional left hemispace. However, target detection accuracy did not change. Bromocriptine thus had a differential impact on the exploratory-motor versus sensory-perceptual components of directed attention. CONCLUSIONS: Our results show that bromocriptine may worsen some aspects of hemispatial neglect in patients with lesions that include the postsynaptic components of ascending dopaminergic pathways.

Adult↗

PubMed1997

Apolipoprotein E genotypes in primary progressive aphasia.

We obtained apolipoprotein E genotyping in a population of 12 consecutive patients who fulfilled rigorous criteria for the clinical diagnosis of primary progressive aphasia (PPA). The allele frequencies were 4% for E2, 83% for E3, and 13% for E4. This pattern of allele distribution was significantly different from the pattern seen in groups of patients either with the clinical diagnosis of probable Alzheimer's disease (PRAD) or the histopathologic diagnosis of Alzheimer's disease (AD). The E4 allele frequency in the group of patients with PPA was in the range seen in control populations and was much lower than the one reported in populations of patients with PRAD or AD. The E4 allele is therefore not a significant risk factor for developing PPA. These results provide neurobiological support for the syndromic distinction of PPA from PRAD and are in keeping with neuropathologic evidence showing that the vast majority of patients with PPA do not have the histopathology of AD. Although we do not yet have neuropathologic information on our patients, these results indicate that the clinical diagnosis of PPA has biological validity in that it identifies a population that is genetically different from the population of patients with a clinical diagnosis of PRAD.

Adult↗

PubMed1995

5-Hydroxytryptamine induces endothelium-independent relaxations of sheep pulmonary vein: role of cyclic nucleotide.

5-Hydroxytryptamine produced concentration-dependent relaxations in isolated sheep pulmonary vein, which were insensitive to removal of the endothelium. 5-Hydroxytryptamine stimulated concentration-dependent increases of cyclic AMP levels in the pulmonary vein, and there was a significant linear correlation between relaxations elicited by 5-hydroxytryptamine and tissue cyclic AMP formations. The soluble guanylate cyclase inhibitor methylene blue (10 microM) failed to block 5-hydroxytryptamine-induced relaxations. The results suggest that 5-hydroxytryptamine-induced relaxations of sheep pulmonary vein are mediated, at least in part, by increases of tissue cyclic AMP levels.

Animals↗