bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological responsiveness to cholinesterase inhibition: A test for exploring the developmental maturity of the cholinergic system
Authors: Torre Carlo 
Published: January 2005

AbstractThe acute mortality caused by two irreversible inhibitors of cholinesterases [disiopropylfuorophosphate (DFP) and diethoxyphosphorylthiocholine, 217 MI‐phospholine iodide] has been investigated on chick embryos at different stages of development.The results demonstrate that the above compounds do not show any acute lethal action when administered before the 9th day of incubation; on the other hand, the administration is regularly followed by death after the 9th day of incubation. The doses are comparable to those causing death in hatched chicks.It has also been observed that no appreciable difference exists in DFP uptake from the yolk before and after the 9th day of incubation and that drug‐induced cholinesterase inhibition is of the same order of magnitude at any developmental stage; the compound pyridine‐2‐aldoxime methanesulfonate (2‐PAM) was a good antidote against DFP acute lethality.It seems likely that between the 8th and the 9th day of incubation the target system of organophosphorus inhibitors, that is, the cholinesterase enzymatic system, reaches a new point of maturation.
Regional properties of dorsal and ventral hippocampus in suppression of intralaminar thalamic unit responses
Authors: Burchell Andrea , McKenzie J. S. , Rogers D. K. 
Published: January 2005

AbstractIn chloralose‐anesthetized. Flaxedil‐paralyzed cats, the suppression of extralemniscal thalamic units by the dorsal and ventral hippocampus was investigated. Unitary responses to test somatic stimuli, recorded in centrolateral and neighboring thalamic nuclei, were interacted with conditioning electrical stimulation in different regions around the hippocampal arch, including the parahippocampal gyrus (entorhinal and retrosplenial areas).Stimulation of dorsal (DHC) and ventral (VHC) hippocampus suppressed roughly equal proportions of responses. However, within each of DHC and VHC, effectiveness depended on the region stimulated. In DHC, Fields CA1 and CA3, subiculum (SUB), and retrosplenial area, but not field CA4 with dentate gyrus (FD), while stimulation of CA1 or subiculum was almost ineffective at currents below 1.0 mA. In VHC the regions were ranked for effectiveness as follows: entorhinal cortex = CA3 > FD >SUB >CAI.No topographic relationship was found between hippocampal region and thalamic loci for unit suppression. Lemniscal‐type unit responses in ventrobasal thalamus were unaffected by stimulation of the hippocampus or parahippocampal gyrus.Interruption of the fornix‐fimbria system prevented suppression elicited from CA1 of DHC or from CA3 of VHC, but not from FD of VHC. It had no effect on suppression elicited from retrosplenial or entorhinal cortex.Hippocampal regional variation of effectiveness in suppressing extralemniscal pathways may contribute to the differential behavioral involvements reported for different hippocampal structures.
Membrane protein and glycoprotein composition of beef brain synaptic vesicles
Authors: Richter‐Landsberg Christiane , Neuhoff Volker , Waehneldt Thomas V. 
Published: January 2005

AbstractSynaptic vesicles were isolated from adult bovine cortical gray matter by differential centrifugation and membrane filtration of a hypoosmotically lysed crude mitochondrial fraction. Vesicle preparations were analyzed for purity by electron microscopy and enzyme assays. Polyacrylamide gel electrophoresis of SDS‐solubilized and 2‐mercaptoethanol‐reduced vesicle membrane proteins revealed 4 major proteins with molecular weights ranging from 17,000 to 60,000, and about 10 minor proteins with molecular weights up to 170,000. The protein profile of the Triton X‐100‐extracted vesicle membranes was less complex, with 1 major protein and 5 minor bands. The major protein of the Triton extract was identified as a glycoprotein with a molecular weight of 45,000. Two additional minor PAS‐positive bands were seen, with molecular weights of 78,000 and 95,000.
Quipazine exacerbation of a hyperkinetic syndrome: Involvement of brain dopamine and serotonin
Authors: Langlais P. J. , Gabay S. 
Published: January 2005

AbstractQuipazine (5–25 mg·kg−1, s.c.) was given to rats in which a hyperkinetic syndrome had been previously induced by administration of β;,β′‐iminodiproprionitrile (IDPN). Quipazine produced a significant increase in the circling behavior and choreiform head and neck movements, characteristic of the syndrome. This response could be blocked by pretreatment with the serotonin antagonists, SQ10, 631 (25 mg·kg −1, i.p.) and methysergide (5.0 mg·kg−1, i.p.), as well as the dopamine receptor antagonist, haloperidol (0.5 mg·kg−1, i.p.). These observations are discussed with respect to the nature of the involvement of brain serotonergic and dopaminergic systems in quipazine action on these hyperkinetic disturbances.
Response properties of cells in the dorsal lateral geniculate nucleus of the albino rat
Authors: Anderson Kenneth V. , Lemmon Vance , Rosing Howard S. 
Published: January 2005

AbstractThe response patterns of cells in the dorsal lateral geniculate nucleus of the albino rat were studied in order to examine the functional organization of the lateral geniculate nucleus. Both photic stimulation and electrical stimulation of the optic tract were used to activate single units in the lateral genicualte nuclei. Three different types of response patterns were fond for principal cells, while interneurons all had similar response patterns. The first class of principal cells, E‐S cells, responded to stimulation with a period of excitation, followed by a period when activity was suppressed. A second class of cells, S cells, responded to photic stimulation with an initial period when activity was suppressed. The final class of cells, E cells, responded with a period of excitation followed by a return to spontaneous rates of firing. The response patterns of E cells suggest that this type of principal neuron does not receive feedback inhibition of the type proposed in previous models of the lateral geniculate nuclei. Based on these and other and other observations, a new model of the functional organization of the lateral geniculate nuclei is proposed.
Amino acid incorporation into total protein and levels of S‐100 protein in discrete rat brain areas after prolonged protein or amino acid restriction
Authors: Rosengren L. , Wronski A. , Haglid K. G. , Jarlstedt J. , Rönnbäck L. 
Published: January 2005

AbstractYoung adult rats were fed an isocaloric diet for 28 days. The diet consisted of either 22% casein, or protein‐restricted food consisting of a 5% mixture of soy and whey protein, or a synthetic amino acid mixed diet devoid of the essential amino acids tryptophan, valine, lysine, and threonine.The level of the nervous tissue‐specific S‐100 protein was quantified immunoelectrophoretically in 9 different brain areas. A marked decreased of S‐100 was observed in hippocampus and posterior part of the cerebellar vermis per g wet weight in protein‐restricted rats. An additional lowering was noticed in sensory motor cortex per mg soluble protein. This effect was potentiated with the amino acid deficient diet.The in vitro incorporation of 3H‐leucine into cerebellar proteins was slightly decreased in the low protein‐fed rats, and more markedly decreased in those receiving an amino acid‐restricted diet.
Regional properties of dorsal and ventral hippocampus in suppression of intralaminar thalamic unit responses
Authors: Burchell Andrea , McKenzie J. S. , Rogers D. K. 
Published: January 2005

AbstractIn chloralose‐anaesthetized, Flaxedil‐paralysed cats, the suppression of extralemniscal thalamic units by dorsal and ventral hippocampus was investigated. Unitary responses to test somatic stimuli, recorded in centrolateral and neighbouring thalamic nuclei, were interacted with conditioning electric stimulation in different regions around the hippocampal arch, including parahippocampal gyrus (entorhinal and retrosplenial areas). Stimulation of dorsal (DHC) and ventral (VHC) hippocampus suppressed roughly equal proportions of responses. However, within each of DHC and VHC, effectiveness depended on the region stimulated. In DHC, fields CA1 and CA3, subiculum (SUB), and retrosplenial area, but not field CA4 or dentate gyrus, usually suppressed extralemniscal units at currents below 1.0 mA. In VHC, the most effective regions were entorhinal cortex, CA3, and CA4 with dentate gryus (FD), while stimulation of CA1 or subiculum was almost ineffective, at currents below 1.0 mA In VHC, the regions were ranked for effectiveness: Entorhinal cortex = CA3> FD > SUB > CA1. No topographic relationship was found between hippocampal region and thalamic loci for unit suppression. Lemniscal‐type unit responses in ventrobasal thalamus were unaffected by stimulation of the hippocampus or parahippocampal gryus. Interruption of the fornix‐fimbria system prevented suppression elicited from CA1 of DHC, or from CA3 but not FD of VHC. It had no effect on suppression elicited from retrosplenial or entorhinal cortex. Hippocampal regional variation of effectiveness in suppressing extralemniscal pathways may contribute to the differential behavioural involvements reported for different hippocampal structures.
The effect of acetylcholine and dopamine on the caudate spindle in cats
Authors: Keane P. E. , Hall R. C. 
Published: January 2005

AbstractElectrocortical activity was recorded in cats whose caudate nuclei were perfused and electrically stimulated using a push‐pull cannula. Electric stimulation invariably induced spindles (10—14Hz) in the ipsilateral frontal cortex. Perfusions of acetylcholine together with physostigmine reduced the number of spontaneous spindles, the response to electric stimulation and induced behavioural arousal. This effect was atropine‐sensitive. Perfusions of dopamine with or without tranylcypromine had no significant effect on the number of spontaneous to electric stimulation. Injections of both acetylcholine and dopamine into the cuadate nucleus invariably induced spontaneous spindles and slow waves. The significance of acetylcholine and dopamine in the caudate nucleus initiating caudate spindles and their significance in controlling arousal is discussed.
Nuclear, nucleolar repair, or turnover of dna in adult rat brain
Authors: Wintzerith M. , Wittendorp E. , Rechenmann R. V. , Mandel P. 
Published: January 2005

AbstractLabeled thymidine administered to adult rats is incorporated at a low level into brain DNA as shown by biochemical and autoradiographic methods. This incorporation takes place in part into neuronal nuclei and nucleoli and also into glial nuclei. While incorporation into glial nuclei is interpreted to represent known glial cell proliferation, incorporation into neuronal nucleoli may be related to nucleolar DNA synthesis, which in turn is responsible for the regulation of nucleolar RNA synthesis. It could also be due to DNA repair synthesis. Assuming this latter phenomenon, our results suggest that nucleolar DNA is more sensitive than chromosomal DNA to ionizing radiations and other factors.
Cyclic 3′, 5′‐nucleotides in extracellular fluids of neural systems
Authors: Cramer Hinrich 
Published: January 2005

AbstractThe cyclic nucleotides (CN) cAMP and cGMP occur in considerable amounts in body fluids such as urine, blood and cerebrospinal fluid (CSF). Whether changes in the CN concentrations of blood and CSF reflect metabolic events within the nervous tissues is a relevant question both in terms of possible roles of CN and of clinical diagnostic purposes. Studies are reviewed which show that cAMP is released from brain slices and from intact peripheral ganglia upon stimulation by electric pulses or exposure to biogenic amines in vitro. By using a prelabeling method with 14C‐adenine evidence is presented that cAMP is released preferentially from a membrane‐associated pool functionally linked to the action of neurotransmitters. In the CSF compartment which is closely related to the extracellular space of the central nervous system, CN levels are in a dynamic equilibrium. An attempt is made to estimate the magnitude of flux rates following inhibition of efflux from the compartment. CN seem to be cleared from the CNS, at least in part, by the choroid plexuses which contain high activities of CN phosphodiesterase but also of adenylate cyclase, possibly related to their secretory and homeostatic functions. Release into and rapid removal from extracellular compartments by transport and degradation may be important means to limit the actions of CN in cells. Whether extracellular CN, in addition, have regulatory functions of their own still remains a matter of speculation.
Spatial propagation of associations in a cortex‐like neural network model
Authors: Wigström Holger 
Published: January 2005

AbstractA neural network model is studied, having associative memory properties and allowing retrieved associations to propagate within the network. It is intended as a tentative description of the cerebral cortex consisting of “pyramidal cells” with modifiable synapses and “stellate cells” providing feedback through excitatory and inhibitory recurrent pathways.The model is based on some general assumptions: Learning occurs through facilitation of synapses which depends on simultaneous pre‐ and postsynaptic activity (two‐conditional facilitation). Connections within the network are realizations of a random process, implying that nearby cells are more likely to be connected than distant ones. The two‐conditional facilitation makes it possible for an output signal pattern which occurred in conjunction with a certain input pattern to be retrieved later by reapplying the particular input, the model working as an associative memory. The random connections and the operation of the stellate cell models as linear threshold units give rise to pattern separation in the feedback link. This, in addition to the fact that patterns form associations with themselves, is of importance during the associative recall enabling the network to attain alternative stable modes of activity each corresponding to a learned association.It is shown that a learned pattern of activity which is retrieved, ie, a stable mode, can propagate across the surface of the network. The mode of activity evoked through a certain association may get into contact with modes originating from different associations, forming a stable or slowly moving boundary between the interacting modes. The model is discussed in relation to some properties of the visual system.
On potassium functional feedback in neuromuscular junction
Authors: Matyushkin D. P. , Shabunova I. A. , Sharovarova G. M. , Vinogradova I. M. 
Published: January 2005

AbstractThe dependance of the reversal potential (Erev) of intracellular end‐plate potentials (epp) on activity patterns was studied in frog neuromuscular preparations. A shift of Erev to the positive side was found with change in frequency of stimulation from 1/sec to 50/sec. This shift corresponds to the increase of potassium concentration in the synaptic cleft to 7.0 mM. The effect of potassium concentration [K+]0 in the bath solution on quantal content (m) of epp was studied. The quantity m increased when [K+]0 was varied within the range 4.7–8.7 mM; m decreased when [K+]0 was > 8.7 mM. Such a relationship between m and [K+]0 is accounted for by the combined effect of potassium on transmitter secretion and electrongenic processes in motor nerve terminals.The correlation between the change of m with [K+]0 and initial epp amplitudes was found and was attributed to potassium efflux from post‐synaptic region in varying quantity depending on the initial epp amplitudes. A scheme of synaptic self‐regulation by means of potassium feedback is suggested.
Induction of pinocytosis in cerebral vessels by acute hypertension and by hyperosmolar solutions
Authors: Hansson Hans‐Arne , Johansson Barbro B. 
Published: January 2005

AbstractA new approach is described to study the mechanism of protein leakage through the endothelial cells in acute hypertension and after intracarotid infusion of hyperosmolar solutions. The luminal surface of the cerebrovascular endothelial cells was labeled with choleragenoid‐peroxidase before the blood‐brain barrier (BBB) dysfunction was induced. Numerous pinocytotic vesicles and some trans‐endothelial channels were formed and showed labeling of parts of their membranes.Our results indicate that the mechanism behind the protein leakage induced by hypertension and by hyperosmolar solutions is the same – ie, transendothelial pinocytosis.
Specificity of brain cathepsin D: Cleavage of model peptides containing the susceptible phe‐phe regions of myelin basic protein
Authors: Marks N. , Benuck M. , Hashim G. 
Published: January 2005

AbstractBrain cathepsin D, purified by affinity chromatography on Sepharose pepstatin columns, was incubated with synthetic peptides corresponding to the susceptible regions of the myelin basic protein encompassing the two Phe‐Phe bonds. One peptide, Leu‐Gly‐Arg‐Phe‐Phe‐Gly‐Gly, was cleaved by cathepsin D at the Phe‐Phe bond while another, Val‐His‐Phe‐Phe‐Lys‐Asn‐Gly, was resistant to cleavage. To determine if this was a result of His flanking the Phe‐Phe bond, or chain length on the N‐terminal side, two decapeptides were synthesized differing only in the presence or absence of His adjacent to Phe. The results show that both of the decapeptides were cleaved by cathepsin D at the Phe‐Phe linkages. In addition, prolonged incubation led to release of N‐terminal Lys, indicating an additional cleavage at the Phe‐Lys bond. In contrast to the limited cleavage by cathepsin D, pepsin split all four peptides. These results support earlier work on the limited proteolysis of basic protein at the Phe‐Phe bond and suggest additional sites upon prolonged exposure. Such peptides may have utility as alternative substrates for basic protein or as models for subsequent synthesis of possible inhibitors of the enzyme.
A sensitive radioenzymatic assay for catechol drugs
Authors: Durrett Lenard R. , Ziegler Michael G. 
Published: January 2005

AbstractThis assay measures picogram quantities of catechol drugs and endogenous catecholamines in body tissues and fluids. The catechols are converted to their 3H‐O‐methyl metabolites during incubation with 3H‐S‐adenosylmethionine and the enzyme catechol‐O‐methyltransferase. The radiolabeled compounds are then separated by solvent extraction and thin‐layer chromatography. Most drugs containing the catechol structure can be radiolabeled and separated from norepinephrine and epinephrine by this technique to provide simultaneous measurement of endogenous and exogenously administered catechols. The disposition of isoproterenol in tissues and fluids of man and experimental animals is measured to illustrate the utility of this assay. The reactivity of several commonly administered catechol drugs with COMT is described and the possible implications discussed.
Histochemical localization of carbonic anhydrase in vertebrate nervous tissue
Authors: Parthe V. 
Published: January 2005

AbstractThe histochemical method of Häusler was employed to demonstrate carbonic anhydrase (CA, carbonate hydrolase, 4.2.1.1.) in tissue sections. The CA reaction was inhibited in the presence of 5 mM acetazolamide. In the frog and fish retinas the CA activity was positive in the Müller fiber, the laminated segment of the cones and the myelin of the axons, and was negative in the laminated segment of the rods, the photoreceptor ellipsoid and myoid, the horizontal, bipolar, amacrine and ganglion cells, and the pigment epithelium. In the spinal cord of cat and fish the CA activity was positive in the myelin of the axons, the perineuronal oligodendroglia and the protoplasmic astrocytes, and was negative in the cell body, dendrite, and axon of the neurons and in the fibrous astrocytes. In the dorsal root ganglion of the cat CA reaction was positive in the satellite cells and the myelin, and was negative in the neuronal cell body and its processes. The capillaries in central nervous tissue show no CA reaction. The erythrocyte is CA positive while the mitochondria are CA negative.
Na+, K+‐ATPase and ouabain binding activities of chick embryo dorsal root ganglia supported by and deprived of nerve growth factor
Authors: Skaper Stephen D. , Varon Silvio 
Published: January 2005

AbstractRecently we have shown that nerve growth factor (NGF) influences the coupled movements of Na+ and K+ across the membrane of chick embryo dorsal root ganglion (DRG) and other target cells. These ionic effects of NGF are consistent with a model in which NGF acts through the classical Na+,K+‐ATPase pump. Direct evidence for NGF‐induced alteration of this pump has been sought in the present study through two approaches. In one approach, DRG cell dissociates were incubated for 6 hours without NGF (to allow development of the ionic defect), and [3H]ouabain binding to the cells was measured before and during a delayed administration of NGF. No differences were detected in either total binding or binding time. In the second approach, intact DRG or DRG dissociates were incubated for 6 hours with or without NGF, or received NGF after 6 hours of deprivation, and Na+,K+‐ATPase (ouabain‐sensitive) activity was measured in the corresponding microsomal preparations. Activity levels were found to be the same in all cases, and were unchanged by addition of NGF directly to the enzyme preparations. Different concentrations of Na+, K+, or ATP affected in identical manners the enzyme preparations from NGF‐treated and NGF‐deprived ganglia, speaking against NGF‐imposed changes in the affinities of the corresponding enzyme sites. Also unsuccessful were attempts to reveal NGF‐related differences by testing ouabain‐sensitive ATPase activity (1) in the presence of varying concentrations of cyclic AMP or of Ca2+, (2) after treatment with Triton X‐‐100 or in the presence of vanadate, or (3) on addition of a 100,000g DRG extract. These negative findings are discussed in terms of the Na+,K+‐ATPase hypothesis for NGF action.