RESUMO
Regional cerebral blood flow (rCBF; 133Xe-inhalation method) was investigated in 32 industrial workers (age: 51 +/- 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents.
Assuntos
Circulação Cerebrovascular/efeitos dos fármacos , Memória/efeitos dos fármacos , Solventes/efeitos adversos , Envelhecimento , Aprendizagem por Associação/efeitos dos fármacos , Lobo Frontal/irrigação sanguínea , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Sanguíneo Regional , Comportamento Verbal/efeitos dos fármacosRESUMO
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.
Assuntos
Encéfalo/fisiopatologia , Hemodinâmica , Hipercapnia/fisiopatologia , Adulto , Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Dióxido de Carbono/sangue , Humanos , Masculino , Resolução de Problemas , Respiração , DescansoAssuntos
Córtex Cerebral/irrigação sanguínea , Lateralidade Funcional , Memória/fisiologia , Rememoração Mental/fisiologia , Aprendizagem por Associação de Pares/fisiologia , Adulto , Lobo Frontal/irrigação sanguínea , Habituação Psicofisiológica/fisiologia , Humanos , Masculino , Córtex Motor/irrigação sanguínea , Lobo Occipital/irrigação sanguínea , Lobo Parietal/irrigação sanguínea , Fluxo Sanguíneo Regional , Lobo Temporal/irrigação sanguíneaRESUMO
The effects of piracetam (Nootropil, UCB6215) on mental functions and on regional cerebral blood flow (rCBF) were investigated in eight patients in the presenile age who displayed symptoms of moderate dementia. The double-blind crossover design included nine measurement occasions, each involving rCBF measurement by the 133-Xe inhalation method, ratings of symptoms of dementia, personality changes, and side effects, and a psychometric investigation. Three investigations were included in each of three treatment periods. The first investigation in a period was made without medication. Then either placebo or piracetam 4.8 g/day or 9.6 g/day was given during four weeks with measurements after 2 weekks and 4 weeks. There were intervals of 4 weeks without medication between the treatment periods. Piracetam had no significant effect on either mental functions or rCBF.
