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At least 451 records · Page 25Linked to original sources
PubMed1991

Arteriovenous malformations. Locations and evolution in the fetal brain.

Almost all cerebral arteriovenous malformations in the fetus involve the vein of Galen, although occasionally they may involve the frontal area of the brain instead. In all reported cases arteriovenous malformations have presented some time after 30 weeks as a sonolucent oval lesion located in the midline behind the third ventricle. Previous scans have been normal. Evidence of high output failure such as cardiomegaly, enlarged neck veins, or hydrops predicts a poor outcome.

Aneurysm↗
PubMed1991

Further observations on pineal brain sand formation and evolution in man.

Acervuli obtained from fragments of the human pineal glands of subjects of both sexes and age ranging from 23 to 87 years were analyzed by light microscopy after histochemical stains and by EDS-microanalysis. It was found that the sub-units and acervuli are positive to P.A.S., Alcian Blue pH 2.5, Gomori-Bargmann procedures for the presence of proteins, glycoproteins, proteoglycans and of the neurosecretory material in different layers of the sub-units and acervuli. We suppose that the increase of Mg++ in the sub-unit from the core to the periphery is responsible for the inhibition of following hydroxyapatite deposition and for growth. We suggest that the presence of glycoproteins and proteoglycans can represent the aggregation factor for bindings between disulphide bonds and calcium.

Adult↗
PubMed1991

Temporal evolution of ischemic damage in rat brain measured by proton nuclear magnetic resonance imaging.

We studied the effect of focal cerebral ischemia on the "state" of brain water using proton nuclear magnetic resonance imaging. Focal cerebral ischemia was induced in five halothane-anesthetized rats via tandem occlusion of the left common carotid artery and the left middle cerebral artery. The proton transverse relaxation time, the proton density, and the water diffusion coefficient were measured at various times from the same region of brain tissue from 1.5 to 168 hours after occlusion. Early measurements indicated significant changes in the transverse relaxation time (p = 0.004) and water diffusion coefficient (p = 0.002) of ischemic brain tissue compared with a homologous region from the contralateral hemisphere. However, the transverse relaxation time, proton density, and water diffusion coefficient in ischemic brain tissue showed different temporal evolutions over the study period. Diffusion coefficient weighting was superior to relaxation time and proton density weighting for the visualization of early cerebral ischemia. Our data suggest that nuclear magnetic resonance imaging is sensitive in detecting changes in proton-associated parameters during early cerebral ischemia and confirm significant changes (p less than or equal to 0.01) in the temporal evolution of transverse relaxation times, proton densities, and diffusion coefficients following middle cerebral artery occlusion.

Animals↗
PubMed1999

Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain.

The African savanna ecosystem of the large mammals and primates was associated with a dramatic decline in relative brain capacity associated with little docosahexaenoic acid (DHA), which is required for brain structures and growth. The biochemistry implies that the expansion of the human brain required a plentiful source of preformed DHA. The richest source of DHA is the marine food chain, while the savanna environment offers very little of it. Consequently Homo sapiens could not have evolved on the savannas. Recent fossil evidence indicates that the lacustrine and marine food chain was being extensively exploited at the time cerebral expansion took place and suggests the alternative that the transition from the archaic to modern humans took place at the land/water interface. Contemporary data on tropical lakeshore dwellers reaffirm the above view with nutritional support for the vascular system, the development of which would have been a prerequisite for cerebral expansion. Both arachidonic acid and DHA would have been freely available from such habitats providing the double stimulus of preformed acyl components for the developing blood vessels and brain. The n-3 docosapentaenoic acid precursor (n-3 DPA) was the major n-3-metabolite in the savanna mammals. Despite this abundance, neither it nor the corresponding n-6 DPA was used for the photoreceptor nor the synapse. A substantial difference between DHA and other fatty acids is required to explain this high specificity. Studies on fluidity and other mechanical features of cell membranes did not reveal a difference of such magnitude between even alpha-linolenic acid and DHA sufficient to explain the exclusive use of DHA. We suggest that the evolution of the large human brain depended on a rich source of DHA from the land/water interface. We review a number of proposals for the possible influence of DHA on physical properties of the brain that are essential for its function.

Animals↗
PubMed1982

Evolution of tubulin heterogeneity during mouse brain development.

In this report, we have characterized tubulin subunit heterogeneity and its evolution during mouse brain development, from embryonic to adult stages. A modification of the two-dimensional protein analysis was used to specify these events. The number of isotubulins increases from 6 (4 alpha and 2 beta), in the embryonic brain, to 11 (6 alpha and 5 beta), in the adult. The changes occurring in tubulin heterogeneity are developmentally controlled but it seems that alpha and beta isotubulins are independently regulated: changes in alpha tubulin occur only just before birth whereas the major evolution is concerned with the appearance and accumulation of acidic beta isotubulins throughout development.

Aging↗
PubMed1995

[Nuclear magnetic resonance spectroscopy: methodology and applications to the study of asphyxia neonatorum].

Cerebral metabolism has been extensively studied by magnetic resonance spectroscopy (MRS). MRS allows the study of neonates brain maturation as well as the onset and the evolution of brain injury. The use of phosphorous spectroscopy allows the quantification of phosphorylated metabolites. Thus, the measurement of the relative concentrations of creatine-phosphate and inorganic-phosphate is a prognostic factor of the outcome of a neonate after birth asphyxia. Absolute concentrations have more recently been studied and seem to be more significant. Proton MRS gives access to brain metabolites such as choline, lactate, N-acetyl aspartate and taurine. Its use is more recent than the phosphorous spectroscopy but first results already show its potential in neonatology.

Asphyxia Neonatorum↗
PubMed1994

Cerebral blood flow and effects of cerebrospinal fluid on calcium transport in patients with cerebral infarction.

BACKGROUND AND PURPOSE: In this study we investigated whether cerebrospinal fluid in patients with brain infarction possesses an activity that contributes to the evolution of brain ischemia. As a test, the effect of cerebrospinal fluid on Ca2+ influx into the intracellular space was chosen because this process is a mechanism for vasospasm, platelet aggregation as thrombi, and neuron damage. METHODS: Effects of cerebrospinal fluid taken from 48 patients with cerebral hemispheric infarction on the concentration of cytosolic free Ca2+ in platelets were studied using the fluorescent probe quin-2. Hemispheric cerebral blood flow was measured using 133Xe intravenous injection. RESULTS: Cerebrospinal fluid in 19 of 48 patients with cerebral hemispheric infarction increased the level of cytosolic free Ca2+ in platelets. The course of the disease in the patients who showed a positive effect of cerebrospinal fluid on Ca2+, when compared with that of patients who showed a negative effect, was characterized by a more severe clinical manifestation and mortality. The decrease in hemispheric cerebral blood flow was more marked in both ischemic and contralateral hemispheres in patients with positive effects of cerebrospinal fluid on the level of Ca2+. CONCLUSIONS: These data suggest that the ability of cerebrospinal fluid to evoke Ca2+ influx into the intracellular space in patients with brain infarction is a factor that aggravates ischemic brain damage.

Biological Transport↗