bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oligosaccharide Portion of GM1 Enhances Process Formation by S20Y Neuroblastoma Cells
Authors: Schengrund Cara‐Lynne , Prouty Catherine 
Published: October 2006

AbstractThe oligosaccharide portion of ganglioside GM1 was found to enhance neuritogenesis by S20Y murine neuroblastoma cells grown in vitro. The average length of the neurites produced by cells grown in the presence of the oligosaccharide portion of GM1 was comparable to that of cells grown in the presence of intact GM1. The processes of these cells were significantly longer (p < 0.005, pooled t test) than those of cells grown in the presence of comparable concentrations of sialic acid, lactose, sialyllactose, GD1a, or the oligosaccharide moiety of GD1a. These results suggest that it is the oligosaccharide portion of GM1 that is responsible for the ability of GM1 to enhance process outgrowth by S20Y neuroblastoma cells.
Evidence that Aspartate Aminotransferase Activity and Ketodicarboxylate Carrier Function Are Essential for Biosynthesis of Transmitter Glutamate
Authors: Palaiologos Georgios , Hertz Left , Schousboe Arne 
Published: October 2006

AbstractBased on the selective inhibition of glutamate release in cerebellar granule cells in primary cultures by the aspartate aminotransferase inhibitor, aminooxyacetic acid, and by the ketodicarboxylate carrier inhibitor, phenylsuccinate, a novel model for synthesis of transmitter glutamate is suggested: Glutamate is formed from glutamine in the mitochondrial intramembrane space by phosphate‐activated glutaminase, transported across the inner membrane in exchange with aspartate, transaminated in the matrix to a‐ketoglutarate, which via the ketodicarboxylate carrier is transferred to the cytoplasm, and transaminated to form transmitter glutamate. Such a mechanism would explain the functional role of aspartate aminotransferase in glutamatergic neurons.
Reduced Protein Kinase C Activity in Ischemic Spinal Cord
Authors: Kochhar Abha , Saitoh Tsunao , Zivin Justin 
Published: October 2006

AbstractProtein phosphorylation was evaluated in a rabbit spinal cord ischemia model under conditions where cyclic AMP‐dependent protein kinase (PK‐A) and calcium/phos‐pholipid‐dependent protein kinase (PK‐C) were activated. One hour of ischemia did not affect PK‐A activity significantly; however, PK‐C activity was reduced by more than 60%. In vitro phosphorylation of endogenous proteins by endogenous PK‐C revealed that eight particulate and five cytosolic proteins showed stimulated phosphorylation by PK‐C activators in control tissue, although this stimulation was virtually absent in ischemic samples. When control and ischemic particulate fractions were combined, the endogenous protein phosphorylation pattern under PK‐C‐activating conditions was similar to the ischemic sample, which suggests that inhibitory molecules may be present in the ischemic particulate fraction. In vitro phosphorylation of endogenous proteins under PK‐A‐activating conditions in ischemic tissue was similar to that in control tissue. The results suggest that the PK‐C phosphorylation system is selectively impaired in ischemic spinal cord. In addition to reduced PK‐C‐dependent phosphorylation, an Mr 64,000 protein was phosphorylated in ischemic cytosolic samples, but not in control samples. The phosphorylation of the Mr 64,000 protein was neither PK‐C‐dependent nor PK‐A‐dependent. These altered phosphorylation reactions may play critical roles in neuronal death during the course of ischemia.
[3H]N‐[1‐(2‐Thienyl)cyclohexyl]‐3,4‐Piperidine ([3H]TCP) Binding in Human Frontal Cortex: Decreases in Alzheimer‐Type Dementia
Authors: Ninomiya Haruaki , Fukunaga Reiko , Taniguchi Takashi , Fujiwara Motohatsu , Shimohama Shun , Kameyama Masakuni 
Published: October 2006

Abstract:We studied [3H]N‐[1‐(2‐thienyl)cyclohexyl]‐3,4‐piperidine ([3H]TCP) binding to human frontal cortex obtained at autopsy from 10 histologically normal controls and eight histopathologically verified cases with Alzheimer‐type dementia (ATD). Extensively washed membrane preparations were used to minimize the effects of endogenous substances. In ATD frontal cortex, the total concentration (Bmax) of [3H]TCP binding sites was significantly reduced by 40–50%. The apparent dissociation constant (KD) values showed no significant change. The reduction in binding capacity was also apparent in Triton X‐100–treated membrane preparations, and there was a linear correlation between the number of [3H]TCP binding sites and that of N‐methyl‐D‐aspartate (NMDA)‐sensitive [3H]glutamate binding sites. [3H]TCP binding sites spared in ATD brains retained the affinity for the ligand and the reactivity to NMDA, L‐glutamate, and glycine. These results suggest that the primary change in NMDA receptor‐ion channel complex in ATD brains is the reduction of its number, possibly reflecting the loss of neurons bearing these receptor complexes, and that the functional linkage within the receptor complexes spared in ATD brains remains normal.
Ventricular Cerebrospinal Fluid Monoamine Transmitter and Metabolite Concentrations Reflect Human Brain Neurochemistry in Autopsy Cases
Authors: Wester Per , Bergström Ulrica , Eriksson Anders , Gezelius Christer , Hardy John , Winblad Bengt 
Published: October 2006

Abstract:Concentrations of dopamine (DA), its metabolites 3‐methoxytyramine and homovanillic acid (HVA), noradrenaline (NA), its metabolites normetanephrine (NM) and 3‐methoxy‐4‐hydroxyphenylglycol (MHPG), 5‐hydroxytryptamine (5‐HT, serotonin), and its metabolite 5‐hy‐droxyindoleacetic acid (5‐HIAA) were measured in 14 brain regions and in CSF from the third ventricle of 27 human autopsy cases. In addition, in six cases, lumbar CSF was obtained. Monoamine concentrations were determined by reversed‐phase liquid chromatography with electrochemical detection. Ventricular/lumbar CSF ratios indicated persistence of rostrocaudal gradients for HVA and 5‐HIAA post mortem. Ventricular CSF concentrations of DA and HVA correlated positively with striatal DA and HVA. CSF NA correlated positively with NA in hypothalamus, and CSF MHPG with levels of MHPG in hypothalamus, temporal cortex, and pons, whereas CSF NM concentration showed positive correlations with NM in striatum, pons, cingulate cortex, and olfactory tubercle. CSF 5‐HT concentrations correlated positively with 5‐HT in caudate nucleus, whereas the concentration of CSF 5‐HIAA correlated to 5‐HIAA levels in thalamus, hypothalamus, and the cortical areas. These data suggest a specific topographic origin for monoamine neurotransmitters and their metabolites in human ventricular CSF and support the contention that CSF measurements are useful indices of central monoaminergic activity in man.
(+)‐[3H]MK‐801 Binding Sites in Postmortem Human Brain
Authors: Quarum Merrit L. , Parker Joel D. , Keana John F. W. , Weber Eckard 
Published: October 2006

Abstract:The pharmacological specificity and the regional distribution of the N‐methyl‐D‐aspartate receptor‐associated 5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a,d]cyclohepten‐5, 10‐imine maleate (MK‐801) binding sites in human postmortem brain tissue were determined by binding studies using (+)‐[3H]MK‐801. Scatchard analysis revealed a high‐affinity (KD= 0.9 ± 0.2 nM, Bmax= 499 ± 33 fmol/mg of protein) and a low‐affinity (KD= 3.6 ± 0.9 nM, Bmax= 194 ± 44 fmol/ mg of protein) binding site. The high‐affinity site showed a different regional distribution of receptor density (cortex > hippocampus > striatum) compared to the low‐affinity binding site (cerebellum > brainstem). The rank order pharmacological specificity and stereoselectivity of the high‐(cortex) and low‐(cerebellar) affinity binding sites were identical. However, all compounds tested showed greater potency at the high‐affinity site in cortex. The results indicate that (+)[3H]MK‐801 binding in human postmortem brain tissue shows pharmacological and regional specificity.
Origin and Migration of Oil
Authors: Baker E. G. 
Published: October 2006

A relationship exists between the composition of crude oil and the solubility of the component hydrocarbons in dilute colloidal electrolyte solutions, suggesting that crude oil consists of hydrocarbons that were once solubilized in formation waters. It is not solubility in ordinary water or solubility in complete soap solution that correlates with the composition of oil but, rather, solubility in soap micelles. Because it implies a possible unloading mechanism, this concept is attractive, for it follows that when a soap solution is diluted with water, the soap micelles disperse and the hydrocarbons solubilized therein appear as discrete, filterable oil droplets.
Thus, it would seem that crude oil originates during the compaction of a sedimentary basin by virtue of the fact that sediment hydrocarbons dissolve in waters containing natural solubilizers and then come out of solution as oil droplets. The composition of crude oil as now understood is consistent with this hypothesis. And—most important—it is now possible to formulate meaningful questions, the answers to which, upon investigation in both field and laboratory, will go far toward enabling us to assess the validity of the mechanism presented here.
In addition to the implications regarding the composition of crude oil that are inherent in the hypothesis that crude oil collects from aqueous colloidal electrolyte solutions, there are several interesting implications from the geological viewpoint. To mention one, such a mechanism would lend credence to the suggestion that the source beds of petroleum are not necessarily unique accumulations of hydrocarbons in a limited area but, rather, may generally be coincident with the area from which water is expressed into the porous strata that eventually form the reservoirs.
Spreading of the Ocean Floor: New Evidence
Authors: Vine F. J. 
Published: October 2006

It is suggested that the entire history of the ocean basins, in terms of ocean-floor spreading, is contained frozen in the oceanic crust. Variations in the intensity and polarity of Earth's magnetic field are considered to be recorded in the remanent magnetism of the igneous rocks as they solidified and cooled through the Curie temperature at the crest of an oceanic ridge, and subsequently spread away from it at a steady rate. The hypothesis is supported by the extreme linearity and continuity of oceanic magnetic anomalies and their symmetry about the axes of ridges.
If the proposed reversal time scale for the last 4 million years is combined with the model, computed anomaly profiles show remarkably good agreement with those observed, and one can deduce rates of spreading for all active parts of the midoceanic ridge system for which magnetic profiles or surveys are available. The rates obtained are in exact agreement with those needed to account for continental drift.
An exceptionally high rate of spreading (approximately 4.5 cm/year) in the South Pacific enables one to deduce by extrapolation considerable details of the reversal time scale back to 11.5 million years ago. Again, this scale can be applied to other parts of the ridge system. Thus one is led to the suggestion that the crest of the East Pacific Rise in the northeast Pacific has been overridden and modified by the westward drift of North America, with the production of the anomalous width and unique features of the American cordillera in the western United States. The oceanic magnetic anomalies also indicate that there was a change in direction of crustal spreading in this region during Pliocene time from eastwest to southeast-northwest.
A profile from the crest to the boundary of the East Pacific Rise, and the difference between axial-zone and flank anomalies over ridges, suggest increase in the frequency of reversal of Earth's magnetic field, together, possibly, with decrease in its intensity, approximately 25 million years ago.
Within the framework of ocean-floor spreading, it is suggested that magnetic anomalies may indicate the nature of oceanic fracture zones and distinguish the parts of the ridge system that are actively spreading. Thus data derived during the past year lend remarkable support to the hypothesis that magnetic anomalies may reveal the history of the ocean basins.
Mechanisms of Organic Oxidation and Reduction by Metal Complexes
Authors: Kochi Jay K. 
Published: October 2006

The mechanism of many organic oxidation and reduction reactions can be described in terms of the formation and reaction of free radicals with metal complexes. Redox (trace-metal) catalysis also involves the oxidation and reduction of radical intermediates with a metal species which oscillates between several oxidation states.
The oxidation and reduction of free radicals with metal complexes follow two general mechanisms, electron transfer and ligand transfer. Direct analogy exists with wholly inorganic descriptions of outer-sphere and innersphere processes.
In an electron transfer or outersphere mechanism the redox process is derived largely by transfer of an electron from reductant to oxidant, with only indirect contributions from the solvent and ligand. Carbonium ion intermediates and transition states are important considerations, and the scission of the β-hydrogen bond is minor during oxidation of alkyl radicals to alkenes. In contrast, ligand transfer or inner-sphere mechanism demands maximum involvement of the ligand in the transition state. Free-radical character prevails; cationic contributions from the organic moiety are minimal.
Oxidation and reduction are conjugate processes. In an electron transfer mechanism the oxidation of alkyl radicals to carbonium ions is conceptually represented by a microscopic reverse reaction in which a carbonium ion is reduced to an alkyl radical. A similar duality exists in the interconversion of carbanions and free radicals by metal complexes.

The reversibility of the ligand transfer process is easier to observe. For example, the chlorine-transfer oxidation of alkyl radicals is represented by a microscopic reverse reduction of alkyl chlorides to alkyl radicals by cuprous chlorides. A ligand transfer counterpart of the
reduction
of radicals

R"⋅+Cu
II
Cl

n

⇋R-Cl+Cu
I
Cl

n
n-1

can also be described.
Hopefully, these simple redox mechanisms will be utilized in rationalizing complex reactions and formulating new syntheses. The limited number of examples cited in this short review represent only an introduction to the vast area of chemical research to be tapped in the study of the mechanisms and the synthetic utility of oxidation-reduction reactions and catalysis.
Human Echo Perception
Authors: Rice Charles E. 
Published: October 2006

It has been shown that human test subjects have the ability, under controlled laboratory conditions, to use echoes to detect the presence or absence of targets placed before them. In addition, blind and sighted persons have been able to detect a target monaurally, to make simple shape discriminations, and to locate a target in space. Signal, environmental, and individual variability affect performance in a measurable fashion.
This research is an initial step in measuring the limits of a human being's ability to use echoes as a source of information about his physical surroundings. At this point it seems unlikely that the unaided human ear can rival the bat's auditory system for echo perception. It may be, however, that modern technology can partially bridge the evolutionary gap and bring more useful echoes to man's ear than those it now receives. Such an accomplishment would allow us to examine the extent to which man might benefit from this means of sensing his environment.
Eastern North American Archaeology: A Summary
Authors: Griffin James B. 
Published: October 2006

The initial occupation of Eastern North America was by small bands of people who gained their livelihood by hunting and gathering. As time passed, the occupants of different regions became increasingly familiar with the available natural resources. The development or introduction of new tools and devices enabled the people to exploit their environments more effectively, until, by Late Archaic times, population size had increased, in terms both of density within a given area and number of people in individual social units.
The initial agricultural productivity aided the culmination of the long cultural traditions in the remarkable productions and practices of the Hopewellian complexes of Middle Woodland times. The major Hopewellian centers reflect the marked change in societal organization and patterns. The costumes of the dead and the manner of their burial clearly reflect individual status differentiations, while artistic creativity is probably to be equated with incipient specialization of labor. Many of the Mississippian societies reached an even more advanced plateau of cultural development, with fortified towns, an organized priesthood, dominant hereditary chiefs, political and military alliances, and a well-developed class system.
The details of the cultural development in Eastern North America are unique, but the general trend may be regarded as a common one in human society, and the patterns of behavior, as analogous to those developed by other peoples in other areas of the Old World and the New.
The Role of Intuition
Authors: Wilder R. L. 
Published: October 2006

"Intuition," as used by the modern mathematician, means an accumulation of attitudes (including beliefs and opinions) derived from experience, both individual and cultural. It is closely associated with mathematical knowledge, which forms the basis of intuition. This knowledge contributes to the growth of intuition and is in turn increased by new conceptual materials suggested by intuition.
The major role of intuition is to provide a conceptual foundation that suggests the directions which new research should take. The opinion of the individual mathematician regarding existence of mathematical concepts (number, geometric notions, and the like) are provided by this intuition; these opinions are frequently so firmly held as to merit the appellation "Platonic." The role of intuition in research is to provide the "educated guess," which may prove to be true or false; but in either case, progress cannot be made without it and even a false guess may lead to progress. Thus intuition also plays a major role in the evolution of mathematical concepts. The advance of mathematical knowledge periodically reveals flaws in cultural intuition; these result in "crises," the solution of which result in a more mature intuition.
The ultimate basis of modern mathematics is thus mathematical intuition. and it is in this sense that the Intuitionistic doctrine of Brouwer and his followers is correct. Modern instructional methods recognize this role of intuition by replacing the "do this, do that" mode of teaching by a "what should be done next?" attitude which appeals to the intuitive background already developed. It is in this way that understanding and appreciation of new mathematical knowledge may be properly instilled in the student.
Physiological Role of Pleasure
Authors: Cabanac Michel 
Published: October 2006

A given stimulus can induce a pleasant or unpleasant sensation depending on the subject's internal state. The word alliesthesia is proposed to describe this phenomenon. It is, in itself, an adequate motivation for behavior such as food intake or thermoregulation. Therefore, negative regulatory feedback systems, based upon oropharingeal or cutaneous thermal signals are peripheral only in appearance, since the motivational component of the sensation is of internal origin. The internal signals seem to be complex and related to the set points of some regulated variables of the "milieu interieur," like set internal temperature in the case of thermal sensation. Alliesthesia can therefore explain the adaptation of these behaviors to their goals. Only three sensations have been studied— thermal, gustatory, and olfactory, but it is probable that alliesthesia also exists in such simple ways as in bringing a signal, usually ignored, to the subject's attention. For example, gastric contractions, not normally perceived, are felt in the state of hunger. Since alliesthesia relies on an internal input, it is possible that alliesthesia exists only with sensations related to some constants of the "milieu interieur" and therefore would not exist in visual or auditory sensations. As a matter of fact, luminous or auditory stimuli can be pleasing or displeasing in themselves, but there seems to be little variation of pleasure in these sensations, that is, no alliesthesia. There may be some esthetic value linked to these stimuli but it is a striking coincidence that they are in themselves rather neutral and that it is difficult to imagine a constant of the "milieu interieur" which could be possibly modified by a visual or an auditive stimulus—such as light of a certain wavelength or sound of a given frequency.
In the light of this theory, it is possible to reconsider the nature of the whole conscious experience. The existence of alliesthesia implies the presence of internal signals modifying the conscious sensations aroused from peripheral receptors. It is therefore necessary to question the existence of sensations aroused by direct stimulation of central receptors, such as hypothalamic temperature detectors, osmoreceptors, and others. Does their excitation arouse sensations of their own, or does the sensation have to pass through peripheral senses? Only human experimentation could answer this question. In the same way, it is possible that self-stimulation of the brain is pleasant, not by giving a sensation in itself, but because the electrical stimulus, renders peripheral stimuli pleasant.