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At least 973 records · Page 54Linked to original sources
PubMed1995

Cerebral blood flow and brain function in hypertension.

In mild hypertensive patients, regional cerebral blood flow, measured by positron emission tomography, was reduced in the frontal cortex and basal ganglia compared with normotensive patients. In moderate to severe hypertensive patients, cerebral oxygen metabolism was diminished, although the patients were neurologically intact. In elderly hypertensives, white matter vascular lesions on brain imaging were more frequent and cognitive function was impaired, compared with age-matched normotensives. In nontreated spontaneously hypertensive rats (SHR), local cerebral blood flow was decreased in the cortex and thalamus, compared with normotensive rats (NTR). Spatial memory and learning in maze tests were more impaired in aged SHR than in old NTR or young SHR. This impairment was related to decreased cerebral glucose utilization in the medial septal nucleus, hippocampus, and other regions of the brain. Reduced cerebral blood flow, increased media thickness of the cerebral arteries and impaired cognitive function in SHR were improved by long-term antihypertensive treatment. In humans as well as animals, long-standing hypertension per se leads to reductions in cerebral blood flow, metabolism, and cognitive function, each of which possibly may be improved by controlling hypertension with long-term antihypertensive treatment.

Animals↗
PubMed1996

Level of care options for the low-functioning brain injury survivor.

During the early stages of recovery from severe brain injury many patients are comatose or minimally responsive. Rehabilitation for these low-functioning survivors traditionally includes acute medical care and transfer to a skilled nursing facility or acute rehabilitation. Concerns have been expressed that customary treatment options are ineffective, costly, or both. In response, 'intermediate'-level programmes designed to provide effective, cost-efficient rehabilitation have emerged. The purpose of this paper is to provide information regarding outcome of severe brain injury and the early rehabilitation needs of survivors. Common characteristics, advantages, and disadvantages of various intermediate programmes, including 'subacute' and 'transitional' rehabilitation, are discussed and contrasted.

Brain Damage, Chronic↗
PubMed1983

Plasmodium yoelii: blood oxygen and brain function in the infected mouse.

The carriage of oxygen by the blood and the in vivo response of the brain were investigated in mice infected with a lethal strain of Plasmodium yoelii. All mice with parasitaemia exceeding 70% were severely anaemic (Hb 3.5 +/- 1.8 g/dl; mean +/- 1 SD), acidotic (blood pH 7.04 +/- 0.06) and hypoglycaemic (blood glucose 0.6 +/- 0.76 mumol/ml). The oxyhaemoglobin dissociation curve (ODC) of blood from heavily infected mice was shifted right as compared to controls, but the increase in p50 was less than expected from the accompanying acidosis. The reduced shift right was due to a decrease in the 2,3-DPG/Hb ratio in infected animals (0.72 +/- 0.12, n = 17 vs 1.10 +/- 0.09, n = 12 in controls). Despite the severity of terminal infection, the cerebral pH and the relative steady-state concentrations of PCr, ATP and Pi measured in vivo by nuclear magnetic resonance (31P NMR) were normal. Alterations in brain energy status and pH cannot account for cerebral signs or death in this proposed mouse model of cerebral malaria.

Adenosine Triphosphate↗
PubMed1997

Functional brain imaging and aging in schizophrenia.

Patients with schizophrenia, even early in the course of illness, show some similarities in their brain-imaging findings to those in older normal controls: for example, ventricular enlargement and diminished functional activity in the frontal cortex. These findings suggest a possible similarity between the normal aging process and schizophrenia, or the possible existence in some schizophrenic patients of progressive processes that prematurely affect the brain in ways analogous to normal aging. In contrast to other brain regions, the basal ganglia in schizophrenia may show an atypical pattern of volumetric and metabolic change over time, possibly because of the effects of neuroleptic treatment. However, age and illness duration are highly correlated in our samples. Interpretation of imaging results is limited by the lack of studies in an adequate number of either first-break or older schizophrenic patients and the dearth of studies with longitudinal designs.

Adult↗
PubMed1983

Ceramide synthesis from free fatty acids in rat brain: function of NADPH and substrate specificity.

At the subcellular level, the synthesis of ceramide from free lignoceric acid and sphingosine in brain required reconstituted enzyme system (particulate fraction, heat-stable and heat-labile factors) and pyridine nucleotide (NADPH). The mitochondrial electron transfer inhibitors (KCN and antimycin A), energy uncouplers (oligomycin and 2,4-dinitrophenol), and carboxyatractyloside, which prevents the transport of ATP and ADP through the mitochondrial wall, inhibit the synthesis of ceramide in the presence of NADPH but have very little effect in the presence of ATP. Similar to the synthesis of ceramide, the synthesis of ATP from NADPH and NADH by the particulate fraction also required cytoplasmic factors (heat-stable and heat-labile factors). Moreover, ATP, but not its analog (AMP-CH2-P-O-P), can replace NADPH, thus suggesting that the function of the pyridine nucleotide is to provide ATP for the synthesis of ceramide. The cytoplasmic factors were not required for the synthesis of ceramide in the presence of ATP. The maximum velocity for synthesis of ceramide from free fatty acids of different chain lengths (C16-C26) was bimodal, with maxima around stearic acid (C18) and behenic acid (C22). The relative rate of synthesis of ceramide parallels the relative distribution of these fatty acids in brain cerebrosides and sulfatides.

Animals↗
PubMed2001

Electric source imaging of human brain functions.

We review recent methodological advances in electromagnetic source imaging and present EEG data from our laboratory obtained by application of these methods. There are two principal steps in our analysis of multichannel electromagnetic recordings: (i) the determination of functionally relevant time periods in the ongoing electric activity and (ii) the localization of the sources in the brain that generate these activities recorded on the scalp. We propose a temporal segmentation of the time-varying activity, which is based on determination of changes in the topography of the electric fields, as an approach to the first step, and a distributed linear inverse solution based on realistic head models as an approach to the second step. Data from studies of visual motion perception, visuo-motor transfer, mental imagery, semantic decision, and cognitive interference illustrate that this analysis allows us to define the patterns of electric activity that are present at given time periods after stimulus presentation, as well as those time periods where significantly different patterns appear between different stimuli and tasks. The presented data show rapid and parallel activation of different areas within complex neuronal networks, including early activity of brain regions remote from the primary sensory areas. In addition, the data indicate information exchange between homologous areas of the two hemispheres in cases where unilateral stimulus presentation requires interhemispheric transfer.

Brain Mapping↗
PubMedDate not supplied

Laboratory of Caribbean Brain Research Organization in the decade of the brain midpoint. Results in reaching behavior--interferences of subcortical motor centers, neurotransmitter blocking and brain function modeling.

CARIBRO was founded in response to the United Nations declaration that the 1990s be designated the Decade of the Brain. The Program of Action is: 1. Annual meetings; 2. Training courses of the Caribbean School of Neurosciences; 3. Network scientific programs; 4. Fellowship programs; and 5. Dissemination of information on neuroscience. In the same program, a CARIBRO Laboratory was created in one of the Medical Faculties of Havana with the aim to teach students from the Caribbean in neuroscience research. As part of this program, we have been working in lateralized motor functions. Preliminary results in rats show that reaching acquisition allows classification of the animals as right-handed (40%), left-handed (40%), and ambidextrous (20%). Electrolytic lesion of caudate nucleus or amygdala impairs lateralized response. Contralateral lesions increase reaching attempts. Ipsilateral lesions to the preferred forepaw do not affect the reaction. The results remain the same 10, 20, and 90 d after the interference. Pharmacological experiments showed that trihexiphenidil (0.1 mg/kg i.p.) induced handedness reversion in 50% if the animals, whereas haloperidol (1 mg/kg i.p.) produced immobility, tremor, and autonomic symptoms. This effect remained the same in young as well as in old animals. We are also working on mathematical modelation. In this sense, preliminary reports about a model for synaptic modification in the framework of the Fukushima hypothesis is discussed.

Animals↗