bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sodium exchange between blood, brain, and CSF in normal and hydrocephalic cats
Authors: Hochwald G. M. , Wald A. , Marlin A. E. , Stern J. , Malhan C. 
Published: January 2005

AbstractThe exchange of sodium between blood, brain, and cerebrospinal fluid was studied in normal and kaolin‐induced hydrocephalic cats. The ventricles were perfused to measure fluid formation and Na+ exchange rates. 22Na was added to the perfusion fluid or injected intravenously as a tracer for Na+ movement. Na+ and 22Na were also measured in cortical gray and white matter. Na+ relative specific activities were calculated for brain, effluent fluid, and serum. With 22Na in the perfusion fluid, Na+ exchange was not different from nascent Na+ influx for both normal and hydrocephalic cats. Na+ relative specific activities of cortical gray and white matter were 10 times greater in hydrocephalic than in normal cats. This difference in Na+ relative specific activity for brain may be due to a higher diffusion constant or to a lower brain capillary permeability.When 22Na was given intravenously, the Na+ diffusional exchange for normal cats was less than that measured when 22Na+ was in the perfusion fluid. In hydrocephalic cats, the Na+ diffusional exchange was effectively zero. Na+ relative specific activities of cortical gray and white matter were the same for normal and hydrocephalic cats. These findings suggest that the impaired Na+ diffusional exchange may be due to pathological changes in the choroid plexus.
Developmental changes of RNA, DNA, lipid, protein and glutamic acid decarboxylase of rat forebrain, anterior midbrain, posterior midbrain, and cerebellum
Authors: Gaitonde M. K. , Tannock Christine , Evans Gwyneth 
Published: January 2005

AbstractThe concentration of glutamic acid decarboxylase (μmoles of glutamic acid decarboxylated/hr/gm) was found higher in the anterior midbrain than in several other regions of the adult rat brain. It was the highest in the anterior colliculus.A developmental study of the forebrain, cerebellum, anterior midbrain, and posterior midbrain showed that the four regions behaved as distinct organs as regards the deposition of structural constituents and the activity of glutamic acid decarboxylase. There was evidence of postnatal cell acquisition by the four regions. The rate of accretion of DNA, RNA, phospholipid, and protein was the highest in the cerebellum, but that of glutamic acid decarboxylase was highest in the forebrain during postnatal development. The results indicated that the average size of the cerebellar cell in the adult rat was smaller than that of the cell of the forebrain, anterior midbrain, and posterior midbrian. The phospholipid content compared to that of protein was higher in the posterior midbrain than in the other three brain regions.The presence of fully differentiated GABAergic neurons in the cerebellum appear by the end of the first postnatal week.
Activation of brain typtophan hydroxylase by a phosphorylating system
Authors: Lysz Thomas W. , Sze Paul Y. 
Published: January 2005

AbstractA significant activation of tryptophan hydroxylase (TPH) was achieved by the addition of 1 mM ATP and 10 mM MgCl2 to 100,000g supernatant prepared from mouse midbrain. The activation produced an increase of enzyme activity by 50–70% above control. Cyclic AMP was not a necessary component in the activation as initially suspected; neither was the involvement of a cyclic AMP‐dependent protein kinase detected. The enzyme activation by Mg+2‐ATP was totally retained after dialysis, thus excluding the possibility of an allosteric effect. In contrast to the activation, TPH was found to be sensitive to inactivation by acid phosphatase, a dephosphorylating enzyme. These findings are consistent with the proposal that the enzyme activation may involve a phosphorylation process. Furthermore, the activation by Mg+2‐ATP in the brain preparations was only minimally observed from neonatal mice and could be abolished from adult mice by administration of hydrocortisone. It appears that the phosphorylation process, as postulated here, may be under developmental and hormonal influences.
Cannabis sativa: Ultrastructural changes in organelles of neurons in brain septal region of monkeys
Authors: Myers William A. , Heath Robert G. 
Published: January 2005

AbstractUltrastructural studies of layer V pyramidal neurons of the septal region of rhesus monkeys exposed to smoke of active marihuana and of those exposed to intravenous delta‐9‐THC revealed low volume density and various degrees of fragmentation and disorganization of rough endo‐plasmic reticulum. In contrast, no changes were observed in these neurons of the septal region of control monkeys (unexposed monkeys and one monkey exposed to smoke of inactive marihuana). There were no significant differences in volume density of mitochondria or golgi apparatus between exposed animals and controls.
Molecular forms of cholinesterases in cerebrospinal fluid, blood plasma, and brain tissue of the beagle dog
Authors: Scarsella G. , Toschi G. , Bareggi S. R. , Giacobini E. 
Published: January 2005

AbstractIn the present study we have investigated the activity of AChE and BuChE in the cisternal CSF of the Beagle dog and have outlined the characteristics of the molecular forms of both enzymes. The same enzymes were also investigated in samples from blood plasma and brain tissue. It is concluded that AChE in CSF originates from the spinal cord and brain tissues as a result of some secretory process. A combined origin from both blood plasma and brain tissue appears to be probable for the BuChE of the CSF.
A regional study of electrophoretically separated proteins from the crude synaptosomal fractions of the developing rat brain
Authors: Davis Leonard G. , Brunngraber Eric G. , Routtenberg Aryeh 
Published: January 2005

AbstractAlbino rats of 1, 5, 9, 16, and 25 days of age were sacrificed, and six brain regions were dissected free. Crude synaptosomal preparations from each brain region and age were obtained by differential centrifugation. Protein content in these fractions from the six brain regions increased almost threefold between 1 and 25 days of age. The preparations were delipidated, solubilized, and subjected to polyacrylamide gel electrophoresis. The densitometric patterns of five samples from each age and brain region were analyzed for changes in the relative amount of stained protein bands. Of the polyacrylamide gel‐separated protein bands, 16 regional differences at specific ages and 20 developmental changes in specific brain regions were found to be statistically significant. The hippocampal region showed the greatest number of statistical changes in the protein pattern as a function of age, whereas the cerebellum showed none. The results suggest the importance of considering regional differences in studies of biochemical developmental changes.
Distribution of glutamate in layers of the rabbit hippocampal fields CA1, CA3, and the dentate area
Authors: Nitsch Cordula , Okada Yasuhiro 
Published: January 2005

AbstractThe distribution of L‐glutamic acid in single layers dissected from freezedried sections of the rabbit hippocampus was estimated by means of an enzymatic cycling procedure. Although the regional variation in glutamate content is less than that of other transmitter candidates, there were present significant differences in it between the projection fields of certain fiber connections. Glutamate concentration was highest in the termination areas of commissural fibers and Schaffer's collaterals.
Effects of excitatory and inhibitory amino acids on phasic respiratory neurons
Authors: Toleikis J. R. , Wang L. , Boyarsky L. L. 
Published: January 2005

AbstractThe responsiveness of phasically active brainstem respiratory neurons to several amino acids was investigated in cats under Dial anesthesia. Four‐barreled microelectrodes were used to extrude iontophoretically the putative neurotransmitters L‐glutamate, L‐aspartate, glycine, and gamma‐aminobutyric acid (GABA). L‐glutamate and L‐aspartate caused increased activity when applied to either inspiratory or expiratory neurons and appeared to be equal in efficacy. Likewise, GABA and glycine depressed ongoing phasic neural activity of both inspiratory and expiratory units. In this case, however, the dosage of GABA required to produce a given depression was significantly less than the required dosage of glycine. These findings support the hypothesis that L‐glutamate and/or L‐aspartate may act as excitatory neurotransmitter agents at the synapses of brainstem respiratory neurons and conversely, GABA may act as the natural inhibitory neurotransmitter.
Effects of anoxia and depolarization on the movement of carbon atoms derived from glucose into macromolecular fractions in rat brain slices
Authors: Domańska‐Janik Krystyna , Zalewska Teresa 
Published: January 2005

AbstractIncorporation of U‐14 C‐glucose into macromolecules (lipid, protein and nucleic acid fractions) of rat brain cortex slices was studied in vitro under conditions of anoxia and reoxygenation. Additionally, the influence of depolarization on control and postanoxic U‐14 C‐glucose metabolism was investigated.Potassium‐induced depolarization of the slices lowered their capacity to incorporate 14C from U‐14C glucose into proteins and nucleic acids without any changes in the labeling the lipids. Fifteen and 30 minutes of anoxia depressed the rate of 14C incorporation into each of the above macromolecules. When slices after 15 minutes of anoxia were transferred to an oxygenated medium their capacity to incorporate 14C from glucose into macromolecules was partly restored compared to the control.Excess of potassium in the medium during the reoxygenation period inhibited restoration of the synthetic capacity of the slices except lipids, into which incorporation of 14C was even stimulated under depolarizing conditions.The influence of anoxia and depolarization were investigated also in different classes of lipids and proteins. 14C incorporation into SDS‐extractable and residual proteins and phospholipid fraction containing phosphoinositol was closest to the control during reoxygenation which suggests the relatively highest resistance of these fractions to anoxia.
Similarities in effects of acetylcholine and dopamine on horizontal cells in the fish retina
Authors: Negishi K. , Drujan B. D. 
Published: January 2005

AbstractThe effect of acetylcholine (ACh) on cone‐ and rod‐connected horizontal cells (generating photopic and scotopic L‐type S‐potentials, respectively) in the fish (Eugerres plumieri) retina was compared with that of dopamine (DA), and some similarities were found in the effects. About two‐thirds of the L‐type horizontal cells examined were sensitive to a test solution containing ACh (10 mM in concentration) and BW‐anticholinesterase (BW; 1.0 mM). ACh with BW augmented a center response and attenuated a surround response as did DA (0.2 mM), although the latter effect was more pronounced and longer‐lasting. ACh with BW frequently produced oscillations of the horizontal cell membrane potential as did DA with clonidine (α‐adrenergic stimulant). Phentolamine (α‐adrenergic blocker) interrupted both the effects of DA and ACh on the center and surround responses, while hexamethonium (cholinergic antagonist) appeared to interfere selectively with the effect of ACh. Therefore, the ACh‐induced changes observed in the horizontal cell membrane potential are assumed to be mediated by the adrenergic system in the fish retina.
Effects of some amino acids on horizontal cells in the fish retina
Authors: Negishi K. , Drujan B. D. 
Published: January 2005

AbstractEffects of some amino acids on horizontal cells were examined in the fish (Eugerres plumieri) retina. L‐aspartate (5 mM in concentration) and L‐glutamate (10 mM) consistently depolarized all types of horizontal cells, although the effect of L‐aspartate was more pronounced. γ‐Aminobutyric acid (GABA; 10 mM) consistently hyperpolarized the cone‐connected L‐ and C‐type horizontal cells, whereas the effect on the rod‐connected cells was slight or nonexistent. The hyperpolarizing effect of GABA on the cone‐horizontal cells was markedly diminished by picrotoxin (0.1 mM). Usually, glycine (10 mM) showed slight and variable effects. It merely depolarized some cone‐horizontal cells but weakly hyperpolarized some rod‐horizontal cells. In a few cases, however, glycine began to drastically hyperpolarize the cone‐horizontal cells in retinas that had been repeatedly treated with certain agents used. Taurine and β‐alanine (10 mM each) had negligible effects, although the former slightly depolarized and the latter merely hyperpolarized both cone‐ and rod‐horizontal cells.
Effects of cortical ablation on the neurotoxicity and receptor binding of kainic acid in striatum
Authors: Biziere Kathleen , Coyle Joseph T. 
Published: January 2005

AbstractLesions of the cerebral cortex alter striatal neuronal vulnerability to locally injected kainic acid. Whereas extensive lesions involving the frontal‐parietal‐occipital cortex are most effective, lesions limited to the frontal or to the dorsal‐lateral parietal cortex offer partial protection. The extensive cortical lesions are associated with selective, marked reductions in the presynaptic markers for glutamatergic afferents in striatum. The protective effects of decortication appear between 6 and 24 hours the lesion and are maintained up to 30 days after decortication. Whereas decortication results in only a transient reduction of specific receptor binding of [3H] kainic acid to striatal membranes, lesion of striatal intrinsic neurons with kainic acid causes a delayed but marked reduction in specific binding of the ligand. Coadministration of L‐glutamic acid (1 μmole) with kainic acid (9 nmoles) partially restores the neurotoxic action of kainic acid in the decorticate striatum; GABA, alanine, and proline (1 μmole) are ineffective with regard to restoring kainate's toxicity for striatal GABAergic neurons. These results suggest that afferent input exerts a permissive effect on the neurotoxic action of kainic acid and that neurotoxicity may involve a cooperative interaction between kainic acid at specific receptors on vulnerable neurons and synaptically released endogenous neurotransmitters, in particular L‐glutamic acid.
Some mechanisms underlying actions of ketamine on electromechanical coupling in skeletal muscle
Authors: Marwaha J. 
Published: January 2005

AbstractThe effects on excitation contraction coupling (ECC) of ketamine (a dissociative general anesthetic) were investigated using the sartorius muscle of the frog. Extracellular studies revealed that ketamine depressed action potential production in a concentration‐dependent manner. Ketamine decreased both the conduction velocity and the compound action potential while concomitantly increasing the threshold current. Intracellular studies showed that ketamine caused a slight non‐significant decrease in the membrane potential and also decreased the threshold potential (mechanical threshold). Ketamine (1.5 × 10−4 M and 3.0 × 10−4 M) initially potentiated and then blocked the twitch response elicited by direct muscle stimulation. Both of these effects were statistically different from control values. These findings suggest that ketamine alters action potential production in frog skeletal muscle. This property of ketamine contributes in part to the disruption of ECC observed with this drug. The results suggest that ketamine probably interferes with calcium binding, its release and/or its fluxes which may contribute to the initial potentiation and subsequent depression of twitch tension.
Partition coefficients of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) in erythrocyte lipids in multiple sclerosis
Authors: Berner Bret , Blanco Cesar E. , Ellison George W. , Myers Lawrence W. , Hirsch Hilde E. 
Published: January 2005

AbstractElectron spin resonance (ESR) was used in a search for a possible generalized membrane defect underlying myelin instability in multiple sclerosis (MS). In contrast to most ESR studies of biological membranes, a small, nonelectrolyte spin label, TEMPO, was chosen; its partition coefficient was determined in extracted erythrocyte lipids from MS patients and normal controls. No differences were observed. The advantages and limitations of TEMPO in comparison with lipid spin labels as probes for the study of biological membranes are discussed.
Depth‐duration profile of the immobility reflex: Theoretical implications for its triggering, sustaining, and terminating mechanisms
Authors: Rakshit A. , Klemm W. R. 
Published: January 2005

AbstractImmobility reflex (IR) durations of rabbits were remarkably consistent (weighted average range of 0.36–0.70 minutes/trial), under the special conditions when rabbits were “habituated” by approximately 25 preliminary trials and when termination of IR was operationally defined as the point at which any attempt, even abortive, at righting occurred. When the mean duration for each rabbit was normalized (into quartile duration points) and then rabbits were tested at these points to determine arousal threshold, each rabbit revealed a clear progressive decrease in the “depth” of IR as the duration of a given episode progressed.Both duration and depth were decreased when body hair was removed. The hippocampal EEG revealed persistent theta activity throughout a given trial; but the specific frequency the theta increased briefly just prior to induction of IR and decreased immediately afterwards. In Short‐duration trials, theta frequency increased progressively until the IR terminated spontaneously. In long‐duration trials frequency changes oscillated.Each of these observations in interpreted to support the theory that, during IR, reverberating neural circuits (in the brainstem reticular formation) are activated and their output inhibits spinal motor neurons.
Behavioural effects of chronic treatment with apomorphine in combination with neuroleptic drugs
Authors: Kenny Marie , Leonard B. E. 
Published: January 2005

AbstractGroups of male Wistar rats were injected with either apomorphine alone twice daily for one week or with apomorphine in combination with chlorpromazine or thioridazine. The neuroleptics were adminsitered once daily so that it was possible to assess their duration of effect on the apomorphine responses. Other groups were injected with saline (controls) chlorpromazine or thioridazine.The nature and time of onset and duration of the stereotyped response following apomorphine injection was determined twice daily. In addition, the behaviour of the rats on the hole board apparatus was also assessed after seven days of drug treatment.Apomorphine was found to induce either a “sniffing/burrowing” or a “fighting” stereotypy. Chlorpromazine in creased the latency and reduced the duration of both types of stereotypy. In contrast thioridazine only increased the latency and reduced the duration of response in the “fighting” group. On the hole board apparatus, both neurolepties reduced the ambulation and rearing scores of the “fighting” groups alone.It is suggested that the different types of stereotypy induced by chronic apomorphine administration, and their sensitivity to the two neuroleptics, are mediated by different types of dopamine receptors.
Hippocampal glutamate release after porta cava anastomosis: Reduced sensitivity to ammonia inhibition
Authors: Hamberger Anders , Hedquist Bo , Lundborg Hugo , Nyström Britta 
Published: January 2005

AbstractIn vitro measurements of basal efflux and evoked release of exogenous and endogenous glutamate from rat hippocampus showed that exposition of the tissue to pathophysiological concentrations of ammonium chloride (3 mM) for 40–60 min abolished the KC1‐induced release of endogenous glutamate. Basal efflux of endogenous glutamate was elevated by ammonium chloride with a delay of 30–40 min.In an attempt to link these observations to the pathogenesis of hepatic coma, rats were subjected to porta‐cava anastomosis, and the hippocampal tissue was tested for ammonia sensitivity 3–4 weeks after the operation. The results showed that ammonia perfusion of the tissue was without effect on either basal or KCl‐evoked release of endogenous glutamate. In addition, the utilization of glutamine for glutamate formation was influenced in hippocampal but not cortical tissue form porta‐cava anastomized rats. The results suggest that ammonia is an important factor for the disturbed metabolism of the neurotransmitter pool of glutamate in hepatic failure.
Effect of peptides of bovine myelin basic protein on dermal fibroblasts
Authors: Chiang T. M. , Whitaker J. N. , Seyer J. M. , Kang A. H. 
Published: January 2005

AbstractBovine basic protein (BP) was digested with purified bovine brain cathepsin D to produce well defined BP derived peptides 1–42, 43–88, 43–169, and 89–169. BP and these BP peptides were tested for their effects on cultured human dermal fibroblasts using a concentration range of 0.01–1,000 ng/ml. No effect was found on cellular proliferation, and neither total protein nor collagen synthesis was altered in the presence of these substances. Although preparations of brain which contain a fibroblast‐growth factor also contain BP peptides, these results indicate that the purified BP peptides studied have no detectable biological effect on the growth of human dermal fibroblasts.
Ultrastructural differentiation and synaptogenesis in aggregating rotation cultures of rat cerebral cells
Authors: Lu Elizabeth J. , Brown W. Jann , Cole Ruth , deVillis Jean 
Published: January 2005

AbstractCerebral cortices from fetal rats were dissociated into single cells by either trypsinization or mechanical sieving. Then the cells were allowed to form aggregates in rotation cultures. At 7, 14, 21, 28, and 35 days, aggregates were processed for electron microscopic study of morphological differentiation with special emphasis on synaptogenesis.Whether the tissue was initially dissociated by trypsin treatment or by mechanical sieving, the aggregating cultures did not exhibit any apparent differences in ultrastructural differentiation and synaptogenesis. At day 7, most neurons were immature and the extracellular space was large. Cell processes had not yet branched extensively but did contain numerous microtubules. A few immature synapses were observed. Astrocytes and oligodendrocytes displayed many of their typical cytological features. At day 14, dendritic spines had developed, some of which formed axodendritic spinous synapses. Multilayered myelin sheaths were tightly wrapped around axons. At day 21, synapses appeared mature and their number per unit area was maximal. The extracellular space had greatly decreased. At this age, asymmetrical synapses had increased approximately sixfold, whereas symmetrical synapses increased only fourfold when compared with the 7‐day‐old aggregates. Multifocal degeneration became apparent at 28 days and was accompanied by a significant decline in the number of synapses.
Inhibition of cyclic nucleotide accumulation following hippocampal tetanic potentiation: Effects of diazepam
Authors: Clement‐Cormier Yvonne , DeFrance Jon , Divakaran Putevah , Stanley James , Taber Katherine , Marchand James 
Published: January 2005

AbstractBiochemical studies on the hippocampus of acutely prepared rabbits revealed more than two fold increases in cyclic GMP levels following tetanic potentiation of the pathway from the medial septal region to CA1 pyramidal cells. Diazepam, administered intravenously, prevented the elevation in cyclic GMP levels in this region and also attenuated the post‐tetanic potentiation seen following the presentation of trains at frequencies within theta rhythm. The results imply a modulatory role for cyclic nucleotides in the enhancement of pyramidal cell excitability and suggest that the biochemical mechanism for the psychoactive benzodiazepines may well include the suppression of cyclic GMP levels.