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PubMed2005

Primary pediatric brain tumors: statistics of Taipei VGH, Taiwan (1975-2004).

BACKGROUND: The purpose of the current study was to investigate a hospital series of 986 cases of primary pediatric brain tumors in Taiwan. METHODS: The authors reviewed the database of primary pediatric brain tumors in patients < 18 years of age collected in Taipei Veterans General Hospital (Taipei VGH) from 1975 to May 2004. Age and gender distribution, location, and classification of brain tumors were analyzed. Intracranial tumors with diagnostic imaging were included. Nontumoral lesions, cysts, and vascular malformations were excluded. RESULTS: The mean age of these 986 patients was 7.8 years, and the male to female ratio was 1.4:1. Supratentorial (including pineal-quadrigeminal) located tumors (58.3%) was predominant to infratentorial tumors (41.1%). In these series, 886 patients had either histologic diagnosis (842 patients) or clinical diagnosis (44 patients). The most common 5 categories of tumors were astrocytic tumors (31.1%), germ cell tumors (14.0%), medulloblastomas (13.3%), craniopharyngiomas (8.3%), and ependymal tumors (5.8%). Atypical teratoid/rhabdoid tumors (AT/RTs), a rare but highly malignant tumor, were 2.1%. The high incidence of primary intracranial germ cell tumors correlated with reported series from Japan and Korea. For the remaining 100 patients without diagnostic classifications, the majority were most likely astrocytic tumors in brain stem. CONCLUSIONS: The authors analyzed a large hospital series of primary brain tumors in children. Both histologically verified and unverified tumors were recruited to avoid selective bias. Although it was not a study of a population-based brain tumor registry, it could still be representative of primary pediatric brain tumors in Taiwan.

Adolescent↗

PubMed1995

Effects of amitriptyline on rat plasma and brain content of monoamine precursors and other large neutral amino acids.

Amitriptyline caused decreased concentrations in rat plasma of the amino acids tyrosine and tryptophan, which are precursors to monoaminergic neurotransmitters, and also of those other large neutral amino acids (LNAAs) (valine, phenylalanine, leucine and isoleucine) with which tyrosine and tryptophan compete for the carrier-mediated transport from plasma into the brain. The various LNAAs were, however, not decreased to the same extent. Thus, the relative concentrations, calculated as the ratio of each one of them to the total concentration of LNAAs, were also influenced by amitriptyline. The relative concentrations of tryptophan were decreased while the relative concentrations of phenylalanine and leucine were increased. Those of tyrosine, valine and isoleucine were not influenced by amitriptyline. The relative concentrations of the LNAAs in plasma are considered to be of importance to how much of each of them that will be transported into the brain. Based on this assumption one would have expected that the amitriptyline-induced changes in the relationships between different LNAAs would have caused changes in their brain concentrations in accordance with their relative concentrations in plasma. However, amitriptyline caused decreased concentrations of all LNAAs in rat whole brain. This finding cannot be explained by altered relationships between the LNAAs but must be explained by other mechanisms. Nevertheless, this effect of amitriptyline on brain LNAA concentrations might be of importance to monoamine function.

Adrenergic Uptake Inhibitors↗

PubMed1986

Three-dimensional ultrasound imaging of brain for neurosurgery.

The ultrasound study group at the Departments of Neurosurgery and Electrical Engineering, University of Oulu, has worked since 1980 on the development of ultrasound holographic B (UHB) imaging for clinical use. It has produced images of human brain based on synthetic focusing of data obtained by wide-angle nonfocused transducers. At the same time, clinical ultrasound B-imaging has been applied to brain and spinal cord surgery. On the basis of laboratory and clinical investigations, some of the possibilities of three dimensional ultrasound imaging in neurosurgery are presented. Particularly the role of supplementary three-dimensional ultrasound imaging data in computer-controlled brain surgery is stressed.

Animals↗

PubMed1993

Infrared spectroscopic characterisation of multiple sclerosis plaques in the human central nervous system.

Fourier transform infrared spectroscopy has been used for the characterisation of white matter, grey matter and multiple sclerosis plaques from human central nervous system tissue. We demonstrate significant differences in the infrared spectra of the three types of tissue, which show that an infrared spectroscopic discrimination of multiple sclerosis plaques from healthy brain tissue is possible in principle. The spectral changes reveal pronounced lipid loss in plaques, consistent with the demyelinating nature of the disease. The chronic plaques studied here can also be distinguished from other non-myelinated areas of the brain, based on differences in water content.

Amides↗

PubMed2003

Positron emission tomography imaging in depression: a neural systems perspective.

PET measures of regional glucose metabolism, although chemically nonspecific, are sensitive indices of brain function in the untreated state and following disparate treatments. The continued development of imaging and multivariate statistical strategies is expected to provide an important perspective toward the full characterization of the depression phenotype at the neural systems level. An additional goal is the development of routine, brain-based clinical algorithms that optimize diagnosis and treatment of individual depressed patients.

Antidepressive Agents↗

PubMed2006

Developmental changes in the expression of ATP7A during a critical period in postnatal neurodevelopment.

ATP7A is a P-type ATPase that transports copper from cytosol into the secretory pathway for loading onto cuproproteins or efflux. Mutations in Atp7a cause Menkes disease, a copper-deficiency disorder fatal in the postnatal period due to severe neurodegeneration. Early postnatal copper injections are known to diminish degenerative changes in some human patients and mice bearing mutations in Atp7a. In situ hybridization studies previously demonstrated that ATP7A transcripts are expressed widely in the brain. ATP7A-specific antibody was used to study the neurodevelopmental expression and localization of ATP7A protein in the mouse brain. Based on immunoblot analyses, ATP7A expression is most abundant in the early postnatal period, reaching peak levels at P4 in neocortex and cerebellum. In the developing and adult brain, ATP7A levels are greatest in the choroid plexus/ependymal cells of the lateral and third ventricles. ATP7A expression decreases in most neuronal subpopulations from birth to adulthood. In contrast, ATP7A expression increases in CA2 hippocampal pyramidal and cerebellar Purkinje neurons. ATP7A is expressed in a subset of astrocytes, microglia, oligodendrocytes, tanycytes and endothelial cells. ATP7A is largely localized to the trans-Golgi network, adopting the cell-specific and developmentally-regulated morphology of this organelle. The presence of ATP7A in the axons of postnatal, but not adult, optic nerve suggests stage-specific roles for this enzyme. In sum, the precisely-regulated neurodevelopmental expression of ATP7A correlates well with the limited therapeutic window for effective treatment of Menkes disease.

Adenosine Triphosphatases↗

PubMed2006

Oxidative stress in mouse brain exposed to lead.

This study was carried out to investigate effects of developmental Pb-exposure on antioxidant enzyme activities of mice brain. BALB dams were exposed to 600 p.p.m. of Pb-acetate in drinking water during pregnancy and lactation. Pb-exposure presented significant increase of plasma and brain Pb and 5-aminolevulinic acid (ALA) concentrations of weaned pups. In Pb-exposed 21-day-old pups, activities of superoxide dismutase, glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Re) decreased significantly in hypothalamus, corpora quadrigemina and corpus striatum compared with Na-exposed pups. Regarding 70-day-old pups, Pb-exposure had different effects on antioxidant enzymes of the three brain regions. The activities of GSH-Px and GSH-Re in corpora quadrigemina and GSH-Re in hypothalamus of Pb-exposure group did not decrease significantly. That meant that the lead employed might make occurrence of long-term effect on the antioxidant enzymes possible. The result also implied a correlation between ALA and oxidative stress in mice brain. Based on these results, it seemed that oxidative stress because of decreased antioxidant function, induced by significant accumulation of ALA, might be the main mechanism involved in mice brain neurotoxicity induced by developmental Pb-exposure.

Aminolevulinic Acid↗

PubMed2004

Global cerebral atrophy in early stages of Huntington's disease: quantitative MRI study.

Global brain atrophy was determined in 70 patients suffering from Huntington's disease (HD) and 70 healthy controls, using brain parenchymal fractions calculated from 3D MRI data in a standardized procedure. In HD patients, brain parenchymal fractions were significantly reduced compared to controls in all age groups; the physiological decline with age was less pronounced in HD. However, brain parenchymal fraction values did not allow the prediction of clinical impairment (as assessed by clinical scores). Global brain parenchyma reduction seems to be an early or even constitutional feature of HD, but clinical symptoms appear to reflect regional rather than global atrophy. Overall, MRI-based brain volume quantification correlated with clinical scores clarifies the functional impact of morphological brain alterations.

Adolescent↗

PubMed1996

[Morphological changes in the rat brain after applying electrostimulation to the emotiogenic areas of the lateral hypothalamus].

Celloidin slices of brain were studied histologically by means of Nissl method in Wistar line rats 3 and 8 months after kindling formation initiated by electrostimulation of the lateral hypothalamus emotiogenic zones. part of brain neurons appeared to acquire destructive changes, grow dark and wrinkle, while some of them died. A great number of such neurons were found in the nuclei of base brain, thalamus, hypothalamus and pons varolii with hemorrhages seen in different brain zones. Besides, 8 months after the kindling formation, large spherical bodies painted metachromatically by toluidin blue were found in white substance of many brain zones. These bodies are likely the product of generation and metabolic disorders in myelinated fibres. The data obtained indicate that kindling initiated by hyperexcitation of emotiogenic brain systems results in organic brain disease similar to that in epilepsy.

Animals↗

PubMed2005

An automated approach to connectivity-based partitioning of brain structures.

We present an automated approach to the problem of connectivity-based partitioning of brain structures using diffusion imaging. White-matter fibres connect different areas of the brain, allowing them to interact with each other. Diffusion-tensor MRI measures the orientation of white-matter fibres in vivo, allowing us to perform connectivity-based partitioning non-invasively. Our new approach leverages atlas-based segmentation to automate anatomical labeling of the cortex. White-matter connectivities are inferred using a probabilistic tractography algorithm that models crossing pathways explicitly. The method is demonstrated with the partitioning of the corpus callosum of eight healthy subjects.

Algorithms↗

PubMedDate not supplied

An algorithm for MR imaging of the short T2 fraction of sodium using the FID signal.

Multiecho magnetic resonance imaging of 23Na in the human body could provide valuable information regarding the distribution of the sodium in the intracellular and extracellular spaces in living tissues. Since it is known that more than half the intracellular sodium has a T2 value of less than 3 ms, the conventional spin-echo imaging technique is not appropriate for the quantitative study of sodium in living tissues. A pulse sequence using the three-dimensional planar-integral projection reconstruction algorithm was developed to provide images from the free induction decay (FID) signal and from the spin-echo. Using this imaging sequence, we are able to produce human head images with the FID signal immediately following the 90 degrees radiofrequency pulse thus preserving the signal from the very short T2 components. This technique with a multiple echo imaging scheme may open the possibility of discriminating between intracellular and extracellular sodium compartments in the human brain based on the T2 relaxation properties.

Algorithms↗

PubMed1997

The neural substrates of religious experience.

Religious experience is brain-based, like all human experience. Clues to the neural substrates of religious-numinous experience may be gleaned from temporolimbic epilepsy, near-death experiences, and hallucinogen ingestion. These brain disorders and conditions may produce depersonalization, derealization, ecstasy, a sense of timelessness and spacelessness, and other experiences that foster religious-numinous interpretation. Religious delusions are an important subtype of delusional experience in schizophrenia, and mood-congruent religious delusions are a feature of mania and depression. The authors suggest a limbic marker hypothesis for religious-mystical experience. The temporolimbic system tags certain encounters with external or internal stimuli as depersonalized, derealized, crucially important, harmonious, and/or joyous, prompting comprehension of these experiences within a religious framework.

Epilepsy↗

PubMed1986

Lashley's shift from bacteriology to neuropsychology, 1910-1917, and the influence of Jennings, Watson, and Franz.

From 1910 to 1917, Karl S. Lashley's research moved from bacteriology to neuropsychology through intermediate stages of zoology, comparative psychology, and the psychology of learning. This shift is examined with particular reference to Lashley's associations with John B. Watson, Shepherd I. Franz, and Herbert S. Jennings. Watson's impact was substantial, for he attracted Lashley to comparative psychology and was the source of many of his later research interests. The bridge to neuropsychological research was provided by Franz who trained Lashley in the lesion method of investigating the brain bases of learning. The influence of Jennings, Lashley's Ph.D. supervisor, was most evident in the divergence of the post-1915 interests of Lashley and Watson. Lashley's search for brain mechanisms of learning, as contrasted with Watson's concern with behavioral prediction and control, mirrored a similar earlier difference between Jennings and Jacques Loeb.

Animals↗

PubMed1989

Proteolysis of tau by calpain.

The calpain-induced proteolysis of tau associated with twice-cycled microtubules or from a total brain heat-stable fraction was studied. Twice-cycled microtubule tau was rapidly hydrolyzed by calpain. In contrast, tau purified from the total brain heat-stable fraction was very resistant to degradation by calpain. These results clearly demonstrate that there are at least 2 populations of tau in the brain based on calpain-sensitivity, a calpain-sensitive form that is associated with microtubules and a calpain-resistant form that may represent another population of tau in the brain.

Animals↗

PubMed1992

Authentic and artifactual detection of the E. coli lacZ gene product in the rat brain by histochemical methods.

The accurate detection of a marker gene is fundamental to the assessment of any gene delivery protocol. The use of E. coli lacZ as such a marker gene has become common in studies on gene transfer to the central nervous system. The straightforward histochemical assay that is available to detect the gene product, beta-galactosidase; has made it an attractive system. However, using standard protocols, we have found dramatic non-E. coli lacZ staining in cells with neuronal, glial and endothelial morphology in the normal, adult rat brain. This false staining is primarily in the brainstem, but is evident in cortical and subcortical regions as well. This endogenous reactivity is independent of substrate concentration within the range tested, but is exquisitely sensitive to even small fluctuations in pH. In light of these findings, one must carefully examine any findings of E. coli lacZ gene expression in the rat brain based solely on histochemical analysis of tissue sections.

Animals↗

PubMed1997

Kinetics of phenylalanine transport at the human blood-brain barrier investigated in vivo.

In vivo proton magnetic resonance spectroscopy was used to investigate intracerebral phenylalanine (Phe) concentrations in nine patients with classical phenylketonuria (PKU). The study included serial examinations (n = 31; plasma Phe levels: 0.47-2.24 mmol/l) of patients either receiving a Phe-restricted diet (200 mg Phe per day; four patients) or a diet rich in Phe (1000 mg Phe per day; three patients). No spectrum showed metabolic abnormalities besides elevated Phe. Difference spectroscopy yielded intracerebral Phe concentrations between 0.20 and 0.76 mmol/l. Regional variations between parieto-occipital periventricular brain, frontal brain, and cerebellum were not statistically significant. Data could be fitted assuming saturable Phe transport into the brain, based on a symmetric Michaelis-Menten model (characterized by an apparent Michaelis transport constant, K(t,app), and a maximum transport velocity, Tmax) and constant Phe consumption in the brain cells (described by a velocity Vmax). Non-linear least-squares fitting of the combined data from all patients yielded K(t,app) = 0.16 +/- 0.11 mmol/l and (Tmax / Vmax) = 9.0 +/- 4.1. Carrier saturation and competitive inhibition of the influx of other large neutral amino acids can be expected at plasma Phe levels usually found in PKU patients.

Adolescent↗

PubMed1998

"Brainstem death," "brain death" and death: a critical re-evaluation of the purported equivalence.

The author challenges brain-based diagnoses of death by re-examining the concept of death, its definition, the anatomical criterion, and the clinical signs or tests. Dr. Shewmon challenges the fundamental assumptions underlying brain death: (1) that the brain is the body's "critical system"; and (2) that the body even has a localized "critical system." He does not redefine death, but shifts the anatomical criterion from a single focus (the brain) to the entire body. The clinical tests correspondingly shift from those implying loss of brain function to those implying thermodynamically supracritical microstructural damage diffusely throughout the body. He concludes that the notion of "brain death" as bodily death is logically and physiologically incoherent, and that its replacement by something scientifically more credible would promote not only the sanctity of life, but ironically even transplantation as well.

Age Factors↗

PubMed2004

Identifying corollary discharges for movement in the primate brain.

The brain keeps track of the movements it makes so as to process sensory input accurately and coordinate complex movements gracefully. In this chapter we review the brain's strategies for keeping track of fast, saccadic eye movements. One way it does this is by monitoring copies of saccadic motor commands, or corollary discharges. It has been difficult to identify corollary discharge signals in the primate brain, although in some studies the influence of corollary discharge, for example on visual processing, has been found. We propose four criteria for identifying corollary discharge signals in primate brain based on our experiences studying a pathway from superior colliculus, in the brainstem, through mediodorsal thalamus to frontal eye field, in the prefrontal cortex. First, the signals must originate from a brain structure involved in generating movements. Second, they must begin just prior to movements and represent spatial attributes of the movements. Third, eliminating the signals should not impair movements in simple tasks not requiring corollary discharge. Fourth, eliminating the signals should, however, disrupt movements in tasks that require corollary discharge, such as a double-step task in which the monkey must keep track of one saccade in order to correctly generate another. Applying these criteria to the pathway from superior colliculus to frontal eye field, we concluded that it does indeed convey corollary discharge signals. The extent to which cerebral cortex actually uses these signals, particularly in the realm of sensory perception, remains unknown pending further studies. Moreover, many other ascending pathways from brainstem to cortex remain to be explored in behaving monkeys, and some of these, too, may carry corollary discharge signals.

Animals↗