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I Prohovnik

Publications and source records attributed to I Prohovnik.

99 records · Page 6Linked to original sources
PubMed1981

rCBF measurements by 133Xe inhalation: applications in neuropsychology and psychiatry.

This review describes recent advances in the application of rCBF measurements by the 133Xe-inhalation method to neuropsychological and psychiatric research. Studies mapping cortical activity, as indicated by flow variations during visual, auditory and tactile tasks of varying complexity are described. The bilateral rCBF measurements do also offer information concerning lateralization of mental processes. Some clinical applications in psychiatry are finally reviewed demonstrating the use of the technique in differential diagnosis of dementia of organic ethiology (Alzheimer's disease, multi-infarct dementia) against pseudodementia due to psychosis. The method is also very useful in the study of cases with toxic influence by alcohol and other agents.

Auditory Perception↗
PubMedDate not supplied

Muscarinic and nicotinic contributions to cognitive function and cortical blood flow.

Muscarinic receptor blockade in humans induces a transient memory deficit claimed to mimic aspects of Alzheimer's disease (AD). AD is also strongly associated with a specific blood flow abnormality in parietotemporal cortex; we previously showed that, despite induction of a dementia-like state, scopolamine does not produce these blood flow changes. In the present study, we administered both muscarinic and nicotinic receptor blockade (using scopolamine and mecamylamine) to seven elderly healthy subjects and measured subsequent changes in cognition and cortical perfusion, using the 133Xe inhalation method to quantify regional cerebral blood flow (rCBF). Results confirmed earlier findings of scopolamine-induced memory deficit and frontal cortex flow reduction. Only mecamylamine, however, produced a perfusion deficit in parietotemporal cortex. All effects were transient and dose-dependent. These findings demonstrate the safety and feasibility of differential and combined blockade of nicotinic and muscarinic cholinergic blockade in human subjects. Furthermore, the nicotinic antagonist mecamylamine yields rCBF changes similar to those seen in AD, despite producing only minimal cognitive effects on its own. The rCBF and behavioral manifestations in AD may therefore reflect the functional loss of nicotinic receptors in addition to alterations in other receptor systems.

Aged↗
PubMedDate not supplied

Cerebral hemodynamic response to mental activation in normo- and hypercapnia.

Changes of regional cerebral blood flow from rest to mental activation by a visually presented spatial reasoning test were measured during normo- and hypercapnia in 10 healthy subjects. Hypercapnia, elicited by inhalation of 6% CO2, resulted in similar flow increases in all 32 cortical regions measured. Increases of flow during testing were seen in post-central regions of the brain whether the resting level was augmented by hypercapnia or not. The results show that an elevated local functional level in the cortex causes an automatic local vasodilatory response which is totally independent of the basal level of perfusion and availability of metabolic substrates.

Adult↗
PubMedDate not supplied

Archival, formalin-fixed tissue: its use in the study of Alzheimer's type changes.

Preparing for a retrospective study of senile degeneration in schizophrenia, we had occasion to explore the suitability of an old collection formalin-fixed brains and paraffin blocks for study by modern staining methods. Tissue that had been in formalin for 50 years was embedded in paraffin. Sections were then stained with thioflavine S and with immunoperoxidase stains using Alz 50 and antibodies to paired helical filaments, ubiquitin, and beta-amyloid. In all 4 cases that had originally (50 years earlier) received neuropathologic diagnoses of Alzheimer's disease, large numbers of neocortical senile plaques and neurofibrillary tangles were clearly demonstrated by thioflavine S stain and by immunohistochemistry for paired helical filaments, ubiquitin, and beta-amyloid. In each of 4 other cases, in which the original neuropathologic examination had not revealed Alzheimer's disease, no plaques or tangles were observed. Immunoreactivity with Alz 50 was completely absent after 50 years in formalin. Examination of additional cases of Alzheimer's disease revealed that Alz 50 immunoreactivity was well preserved after 10 years in formalin and completely absent after 30 years in formalin. Alzheimer's disease tissue stored in paraffin for 30 years was clearly stained by all modalities. We conclude that immunohistochemical identification of senile plaques and neurofibrillary tangles is practical even after decades of storage in formalin or paraffin. The applicability of techniques that did not exist when these specimens were collected indicates that the systematic, permanent retention of formalin-fixed material may yield unanticipated future benefits.

Adult↗