bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in Polyamine Concentrations in Amygdaloid‐Kindled Rats
Authors: Hayashi Yasushi , Hattori Yukio , Moriwaki Akiyoshi , Saeki Kiyomi , Hori Yasuo 
Published: October 2006

AbstractConcentrations of the polyamines putrescine, spermidine, and spermine were investigated in the left and right amygdala and in the remaining cerebrum, in which kindling was induced by repeated application of electrical stimulation of the left amygdala of rats. In kindled rats, the concentrations of spermidine and spermine increased slightly, but elevations did not reach significant levels in any brain regions. The most profound increase was detected in the putrescine concentration in all parts of the cerebrum 1–8 h after the final stimulation. These results suggest that the increases in concentrations of polyamines, particularly of putrescine, are involved in the pathogenesis of amygdaloid kindling.
Effect of Desipramine on a Glycoprotein Sialyltransferase Activity in C6 Cultured Glioma Cells
Authors: Broquet Pierre , Baubichon‐Cortay Hélèna , George Pascal , Peschard Marie‐Jo , Louisot Pierre 
Published: October 2006

Abstract:The tricyclic antidepressant desipramine, when added to culture medium, gave rise in C6 rat glioma cells to a decrease of the activity of the enzyme asialofetuin sialyltransferase. The inhibition was dose and time dependent and was observed in both multiplying cells and cells blocked with 2 mM thymidine or depletion of amino acids. This inhibition was rather specific to the sialyltransferase, as under the conditions where this enzyme was inhibited up to 70%, other enzymes such as dolichol phosphate mannose synthetase, glutamine synthetase, and glycerol phosphate dehydrogenase remained unaffected. This inhibition was not reversed after removal of desipramine from the medium and was not observed by direct addition of desipramine to the sialyltransferase incubation assay. Under the same conditions, W‐7 [N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide], which is known to be a potent calmodulin antagonist and an inhibitor of calmodulin‐dependent kinases, gave the same concentration‐dependent inhibition profile of sialyltransferase as desipramine, whereas H‐7 [1‐(5‐isoquinolinylsulfonyl)‐2‐methylpiperazine], which is an inhibitor of protein kinase C and cyclic nucleotide‐dependent kinases, had no effect. So, it is suggested that desipramine inhibits the sialyltransferase activity in C6 glioma cells through a calmodulin‐dependent system.
Vesicular and Ganglionic Norepinephrine in the Rat: Progressive Increase with Age
Authors: Buu Nguyen T. , Debinski Waldemar 
Published: October 2006

Abstract:This study analyzed dopamine (DA) and norepinephrine (NE) in the synaptic vesicles and cytoplasm of brains of rats of 2 months and 14 months. The data revealed a clear NE increase in the synaptic vesicles of the 14‐month‐old rats, contrasting with NE in the cytoplasmic fraction of the rat brain, which remained unchanged with age. Synaptic vesicles from different regions of rat brain, including those from the striatum, consistently exhibited higher NE than DA concentrations, suggesting that they are predominantly noradrenergic. In the brain, DA concentrations in vesicular and cytoplasmic fractions did not vary with age, whereas in the superior cervical ganglia DA and NE concentrations increased in the older rats. L‐3,4‐Dihydroxyphenylalanine administration significantly increased DA without affecting NE in the ganglia of rats of all ages. In the brain, such a treatment significantly raised DA only in the synaptic vesicles of the older rats, suggesting an increased facilitation of DA transport into the synaptic vesicles with age, which may account for the higher vesicular NE in the older rats.
Survival of Chick Embryonic Sensory Neurons in Culture Is Supported by Phorbol Esters
Authors: Bhave Sanjiv V. , Malhotra Ravindra K. , Wakade Taruna D. , Wakade Arun R. 
Published: October 2006

Abstract:Sensory neurons of the chick embryo are supported in culture by several neurotrophic factors, including the phorbol esters. Because phorbol esters are known to activate one of the second messengers, namely, protein kinase C, it was of interest to see if the neurotrophic action of phorbol 12,13‐dibutyrate (PDB) was related to the activation of protein kinase C in sensory neurons. Sensory neurons were obtained from dorsal root ganglia of 10‐day‐old chick embryos and maintained in a serum‐free medium for several days to quantify survival and analyze protein kinase C activity. PDB (30 nM) supported the survival of ± 50% of the total number of neurons plated. This value was comparable to that supported by nerve growth factor (NGF; 40 ng/ml). If PDB and NGF were added together, there was no additive effect on the survival. The protein kinase C activity of the particulate and cytosolic fractions of sensory neurons supported by NGF for 3 days was 1.26 ± 0.1 and 2.9 ± 0.32 pmol/min/mg of protein, respectively. In contrast, neurons supported by PDB showed an ± 500% increase in enzyme activity in their particulate fraction. The enzyme activity of the cytosolic fraction was decreased by ± 40%. If NGF‐supported neurons were treated with PDB (30 nM) for 15 min, protein kinase C activity increased > 400% in the particulate fraction, whereas an ± 50% decrease was observed in the cytosolic fraction. The protein kinase C value, expressed as a ratio of the activities in the particulate to cytosol fractions, showed large increases after phorbol treatment. The ratio was 0.43 in NGF‐supported neurons and increased to 3.57 in PDB‐supported neurons. NGF‐supported neurons treated with PDB for 15 min had a ratio of 4.1. Phorbol‐13‐acetate did not support the survival, nor did it increase protein kinase C activities in NGF‐supported neurons. Because sensory neurons contain substantial amounts of choline acetyltransferase (ChAT) activity, we compared ChAT activity in NGF‐ and PDB‐supported sensory neurons. Values were 21.93 ± 3.7 and 22.09 ± 4.6 pmol of acetylcholine formed/min/mg of protein, respectively. These results suggest that neurotrophic action of PDB on chick sensory neurons is probably mediated through protein kinase C. The present data also suggest that NGF and PDB act on the same subpopulation of sensory neurons of the dorsal root ganglia of the chick to support their survival in culture.
Estimation of Free Dopamine in the Cytoplasm of the Giant Dopamine Cell of Planorbis corneus by Voltammetry and Capillary Electrophoresis
Authors: Chien Jennifer B. , Wallingford Ross A. , Ewing Andrew G. 
Published: October 2006

Abstract:Voltammetric electrodes having a tip diameter of 2–12 μ and microscale capillary zone electrophoresis have been used for dynamic and static monitoring of dopamine in the somal cytoplasm of the giant dopamine neuron of Planorbis corneus. Intracellular dopamine levels can be altered by extracellular application of dopamine or ethanol. The latter experiment provides a means to estimate total stores of endogenous dopamine, and the evidence presented suggests that at least 98% of these stores are bound and not directly accessible to the cytoplasm.
Autoradiographic Characterization and Localization of Quisqualate Binding Sites in Rat Brain Using the Antagonist [3H]6‐Cyano‐7‐Nitroquinoxaline‐2,3‐Dione: Comparison with (R,S)‐[3H]α‐Amino‐3‐Hydroxy‐5‐Methyl‐4‐Isoxazolepropionic Acid Binding Sites
Authors: Nielsen Elsebet Ø. , Drejer Jørgen , Cha Jang‐Ho J. , Young Anne B. , Honoré Tage 
Published: October 2006

Abstract:Using quantitative autoradiography, we have investigated the binding sites for the potent competitive non‐N‐methyl‐D‐aspartate (non‐NMDA) glutamate receptor antagonist [3H]6‐cyano‐7‐nitro‐quinoxaline‐2,3‐dione ([3H]‐CNQX) in rat brain sections. [3H]CNQX binding was regionally distributed, with the highest levels of binding present in hippocampus in the stratum radiatum of CA1, stratum lucidum of CA3, and molecular layer of dentate gyrus. Scatchard analysis of [3H]CNQX binding in the cerebellar molecular layer revealed an apparent single binding site with a KD= 67 ± 9.0 nM and Bmax= 3.56 ± 0.34 pmol/mg protein. In displacement studies, quisqualate, L‐glutamate, and kainate also appeared to bind to a single class of sites. However, (R,S)‐α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) displacement of [3H]CNQX binding revealed two binding sites in the cerebellar molecular layer. Binding of [3H]AMPA to quisqualate receptors in the presence of potassium thiocyanate produced curvilinear Scatchard plots. The curves could be resolved into two binding sites with KD1= 9.0 ± 3.5 nM, Bmax= 0.15 ± 0.05 pmol/mg protein, KD2= 278 ± 50 nM, and Bmax= 1.54 ± 0.20 pmol/mg protein. The heterogeneous anatomical distribution of [3H]CNQX binding sites correlated to the binding of L‐[3H]glutamate to quisqualate receptors and to sites labeled with [3H]AMPA. These results suggest that the non‐NMDA glutamate receptor antagonist [3H]CNQX binds with equal affinity to two states of quisqualate receptors which have different affinities for the agonist [3H]AMPA.
Calmodulin‐Binding Proteins and Calcium/Calmodulin Regulated Enzyme Activities Associated with Brain Actomyosin
Authors: Larson Roy E. , Espindola Foued S. , Espreafico Enilza M. 
Published: October 2006

Abstract:Calcium‐ and calmodulin‐regulated ATPase and protein kinase activities are shown to be strongly associated with brain actomyosin. Similar enzymatic activities and an invariable polypeptide profile on sodium dodecyl sulfatepolyacrylamide gel electrophoresis were obtained for brain actomyosin taken through a solubilization‐precipitation cycle (1.0–0.1 M KC1), or precipitated from buffers containing 1% Triton X‐100 or 10 mM EDTA and 10 mM EGTA. These data suggest a specific complex of brain actomyosin with a protein kinase similar to calmodulin‐dependent kinase II, a 190‐kDa calmodulin‐binding protein (P190), and a calmodulin‐like polypeptide. P190 was the major substrate for endogenous calcium‐dependent phosphorylation. 125I‐Calmodulin overlay technique revealed four major calmodulin‐binding polypeptides associated with brain actomyosin: 50‐and 60‐kDa subunits of the calmodulin‐dependent kinase II, P190, and a high molecular weight polypeptide which is probably fodrin. A fraction enriched in P190 had Ca2+‐ and calmodulin‐stimulated MgATPase activity, but not myosin‐like K‐EDTA ATPase activity. The lack of immunological crossreactivity between brain myosin heavy chain and P190 confirmed that they are distinct molecules.
Formation of [Leu5]Enkephalin from Dynorphin A(1–8) by Rat Central Nervous Tissue In Vitro
Authors: Dixon D. M. , Traynor J. R. 
Published: October 2006

Abstract:[3H]Dynorphin A(1–8) is readily metabolised by rat lumbosacral spinal cord tissue in vitro, affording a variety of products including a significant amount (20% recovered activity) of [3H][Leu5]enkephalin. In the presence of the peptidase inhibitors bestatin, captopril, thiorphan, and leucylleucine, [3H][Leu5]enkephalin was the major metabolic product, accounting for 60% of recovered activity. Production of [3H][Leu5]enkephalin was seen across all gross brain regions. The enzyme responsible for the cleavage has an optimal substrate length of 8–13 amino acids and is inhibited b N‐[1‐(RS)‐carboxy‐2‐phenylethyl]‐Ala‐Ala‐Phe‐p‐aminobenzoate, a site‐directed inhibitor of the metalloendopeptidase EC 3.4.24.15. However the enzymic breakdown also has properties in common with involvement of endo‐oligopeptidase A. Possible consequences of the formation of [Leu5]enkephalin from the smaller dynorphins are discussed.
Acetylcholine Synthesis and Release in the Extensor Digitorum Longus Muscle of Mature and Aged Rats
Authors: Smith Dean O. 
Published: October 2006

Abstract:Uptake of labeled choline and its incorporation into acetylcholine (ACh) were assayed at the neuromuscular junction of the extensor digitorum longus (EDL) muscle of rats aged 11 (mature adult) and 27 (aged) months. Under resting conditions, there were no significant differences in muscle ACh or choline levels. Following a 1‐h incubation in labeled choline, however, tissue from the younger rats contained significantly greater amounts of labeled choline and labeled ACh; the specific activities of ACh and choline were nearly 10‐fold higher in the 11‐month‐old animals, indicating reduced uptake of labeled choline in the older animals. ACh and choline efflux rates under resting conditions did not change with age, indicating an uncoupling of exogenous choline uptake and ACh efflux in EDL during aging. During nerve stimulation (1 Hz), the amount of labeled choline incorporated into ACh was 150% greater in the aged animals. The specific activity of ACh released during stimulation was correspondingly greater in the 27‐month‐old animals, although total ACh released did not change appreciably with age. There were no age‐related differences in choline acetyltransferase activity. Contrasting results were obtained from diaphragm in previous studies; the linkage between choline uptake and ACh efflux was maintained during rest and stimulation in the diaphragm. Hypothetically, these differences between EDL and diaphragm may be related to their diverse activation patterns: EDL is recruited much less frequently and less regularly than diaphragm, a continually active vital muscle.
Effects of Different Semipermeable Membranes on In Vitro and In Vivo Performance of Microdialysis Probes
Authors: Hsiao John K. , Ball Beth Ann , Morrison Paul F. , Mefford Ivan N. , Bungay Peter M. 
Published: October 2006

Abstract:The in vitro and in vivo performance of three different semipermeable microdialysis membranes was compared: a proprietary polycarbonate‐ether membrane made by Carnegie Medecin; cuprophan, a regenerated cellulose membrane; and polyacrylonitrile. When microdialysis probes were tested in a stirred in vitro solution, large and statistically significant differences among the three membranes in extraction of acid metabolites (3,4‐dihydroxyphenylacetic acid, 5‐hydroxyindoleacetic acid, and homovanillic acid) and acetaminophen were found. Polyacrylonitrile had the highest extractions in vitro. In contrast, when microdialysis probes were implanted in vivo (in rat striatum), extraction of acid metabolites and acetaminophen did not differ significantly among the different membranes. These results are consistent with predictions made by a mathematical model of microdialysis and can be explained by the fact that in vitro the main factor limiting extraction is membrane resistance to diffusion, whereas tissue resistance to diffusion plays a more dominant role in vivo. These findings suggest that (aside from differences in surface area), the choice of semipermeable membrane will generally have little effect on in vivo microdialysis results. Furthermore, in vitro measurements of microdialysis probe extractions are not a reliable way of calibrating in vivo performance.
Critique of the Linear Theory of Carcinogenesis
Authors: Brues Austin M. 
Published: October 2006

1) Present data on human leukemogenesis by radiation fail to indicate a linear relation between dose and effect. Because data are scanty, such a hypothesis cannot be ruled out statistically, but it is less probable than a nonlinear or threshold relation.
2) Other instances in which carcinogenic agents have been examined from the standpoint of dose and dose-rate relations show many clear instances where the relation is nonlinear and none in which linearity is unquestionably demonstrated.
3) Theoretical consideration of the probability that a single critical molecular event, such as a mutation, will give rise to cancer indicate that a malignant change must be an extraordinarily improbable result of such a perturbation. It is also very difficult to reconcile this mechanism with the rather comparable spontaneous and induced-cancer incidences in species with greatly different numbers of cells.
4) Any scheme in which multiple events caused by the carcinogen are required to produce a tumor is incompatible with a linear relation, while, if a disordered state of tissue is an important factor, a true threshold may even occur. There is much evidence, from cancer research of all sorts, indicating that one or both of these conditions is involved in the carcinogenic process.
Sterile-Male Method of Population Control
Authors: Knipling E. F. 
Published: October 2006

The principle of animal population control through the use of sexually sterile males has been demonstrated for insects. Sexually sterile males that retain their sexual vigor and behavior will exert greater influence in regulating animal populations than can be achieved by destroying or removing the same number of individuals from the population. This hypothesis is supported by calculations showing theoretical population trends in assumed insect and animal populations subjected to treatments that destroy or eliminate certain percentages of the individuals as compared with a procedure that retains or replaces the same number of males in the population after sterilization. The maximum regulating effect that can be achieved is in direct proportion to the ratio of sterile to fertile males competing for mates.
The advantages of inducing sexual sterility in a natural population of an insect species by chemical or other treatment over the method of rearing and releasing a dominating population of sterile males are considered. It is suggested that the sterile-male method may have practical application for undesirable populations of certain wild animals as well as for insects.
Crystalline Structure and Surface Reactivity
Authors: Gatos Harry C. 
Published: October 2006

The role of crystalline structure in the surface reactivity of predominantly covalent materials has been examined in terms of chemical bonding concepts. In this context a solid surface can be viewed as a giant lattice defect characterized by dangling bonds. Although it is difficult, at the present stage of development of the quantum mechanical approach to surfaces, to define precisely the perturbations resulting from the abrupt termination of the lattice at the surface, a host of experimental observations can be understood by assuming displacements of surface atoms and distortions of bonding configurations in accordance with simple chemical bonding principles.
A purely atomistic approach has been shown to account not only for the chemical behavior but also for certain structural and electrical characteristics of the surfaces considered. A number of phenomena, such as crystal growth and the behavior of certain lattice defects (for example, dislocations), are intimately related to the presence of dangling bonds and the associated distortions of the lattice at the surface.
The Spread of Western Science
Authors: Basalla George 
Published: October 2006

There is no need to summarize the features of this simplified model, which describes the manner in which modern science was transmitted to the lands beyond Western Europe. The graph of Fig. 1 and the examples drawn from science in various lands should have made them clear. It may be in order, however, to reiterate that there is nothing about the phases of my model that is cosmically or metaphysically necessary. I am satisfied if my attempt will interest others to go beyond my crude analysis and make a systematic investigation of the diffusion of Western science throughout the world.Such an investigation would include a comparative appraisal of the development of science in different national, cultural, and social settings and would mark the beginnings of truly comparative studies in the history and sociology of science. The present lack of comparative studies in these disciplines can be attributed to the widespread belief that science is strictly an international endeavor. In one sense this is true. As Sir Isaac Newton remarked in his Principia, "the descent of stones in Europe and in America" must both be explained by one set of physical laws. Yet, we cannot ignore the peculiar environment in which members of a national group of scientists are trained and carry on their research.While I do not hold with the Nazi theorists that science is a direct reflection of the racial or national spirit, neither do I accept Chekhov's dictum that "there is no national science just as there is no national multiplication table. . . ." In emphasizing the international nature of scientific inquiry we have forgotten that science exists in a local social setting. If that setting does not decisively mold the conceptual growth of science, it can at least affect the number and types of individuals who are free to participate in the internal development of science. Perhaps the effect is more profound; only future scholarship can determine the depth of its influence/
Dormancy of Trees in Winter
Authors: Perry Thomas O. 
Published: October 2006

Early dormancy involves a number of phenomena: cessation of active growth, formation of terminal buds, formation of abscission layers in leaves, development of cold resistance, development of winter rest (a chilling requirement), and leaf fall. The buds of some tree species (or some races of a species) have a true rest or winter chilling requirement; usually the roots do not; perhaps the cambium does not. There is a wide range of genetic variation within and between species in response to photoperiod, winter chilling, water nutrients, and other environmental factors which affect the dormancy condition of plants.
During the period of winter rest there are many metabolic and developmental processes going on in the buds and twigs. These processes include respiration, photosynthesis, some cell division, enzyme synthesis, production of growth stimulators, and dissipation of growth inhibitors.
Dormancy of trees can be divided arbitrarily into three phases: early rest, winter rest, and after-rest. Each of these phases is marked by a distinct set of physiological processes. The transition between the three phases is gradual. Some processes of after-rest can proceed even though the winter chilling requirement (winter rest) of a tree has not been completed fully.
Evidence from grafting experiments and chemical treatments to break winter rest, and studies of genetic variability indicate that the processes and phenomena of dormancy are at least partially independent of each other. Different buds and branches and other parts of the same plant may initiate dormancy, break dormancy, and renew vegetative growth independently.
Initiation and cessation of dormancy can be triggered by a number of environmental variables: photoperiod, temperature, nutrition, water, an array of chemicals, and shock treatments. Dormancy regulation must either involve a variety of receptors or involve receptors that are responsive to a variety of stimuli. Unless dormancy is defined in a highly restricted sense (that is, possession of chilling requirement), it is hard to conceive of a single receptor or regulator that controls all of the phenomena of dormancy. A large number of genes are definitely involved and hence a large number of enzymes. The kinds of enzymes, their numbers, and their concentrations can be regulated by manipulating the environment.