bluuebunny/crossref_metadata_2025_split huggingface dataset:
The threshold quantity of nerve required to induce limb regeneration in the chick embryo
Authors: Sisken B. F. , Fowler I. , Barr E. J. , Kryscio R. J. 
Published: January 2005

AbstractWingbuds of 4‐day chick embryos were amputated at the future elbow joint and a segment of embryonic neural tube was implanted longitudinally in the stump. The cross‐sectional area and number of nerve bundles were determined in limbs in which limb regeneration occurred and compared with similar measurments in control limbs without neural tube implant. The number of nerve bundles in regenerated limbs was not significantly greater than in control limbs which did not regenerate. However, the cross‐sectional area of nerve bundles was significantly greater in the limbs that had undergone regeneration. The data support the view that the amount of axoplasm available at the amputation (surface) site is the essential factor in determining the success or failure of regeneration.
Influences of the neural cell adhesion molecule on axon growth and guidance
Authors: Rutishauser U. 
Published: January 2005

AbstractThe neural cell adhesion molecule (NCAM) has been shown to be a ligand in the formation of cell‐cell bonds. This molecule is present on essentially the entire surface of differentiated nerve cells, including the cell body, neurite shaft, and growth cone. In mediating membrane‐membrane adhesion, NCAM appears to ligate with itself, and one of its most obvious functions is in the self‐association of nerve fibers to form fascicles. In most cases fasciculation occurs by the successive elongation of axons along other axons and, therefore, is likely to represent a growth cone‐neurite shaft interaction as well as a shaft‐to‐shaft adhesion. Competition between neurite shafts and the surrounding substrate for growth cone adhesion probably represents a major factor in the branching of nerve bundles. In addition to neurons, NCAM appears on some glial and muscle cells. Recent experiments suggest that this molecule is involved in growth cone guidance along adhesive pathways on glial precursors in the vertebrate central nervous system, and in the initial interaction of axons with muscle prior to synaptogenesis.
Morphological properties and membrane channels of the growth cones induced in PC12 cells by nerve growth factor
Authors: O'Lague P.H. , Huttner S.L. , Vandenberg C.A. , Morrison‐Graham K. , Horn R. 
Published: January 2005

AbstractLarge growth cones were produced in vitro by nerve growth factor (NGF) treatment of multinucleate cells produced by chemical fusion of cells of the neuron‐like clone PC12. These endings were studied both at the light microscopic and ultrastructural levels. The activity of ionic channels at growth cones was recorded with intracellular microelectrodes, patch recording of single channels, and whole cone recording from mechanically isolated growth cones. Morphologically, these large growth cones were characterized by the presence of microspikes and filopodia, by the presence of actin demonstrated immunohistochemically, and by the presence of catecholamine fluorescence. At the ultrastructural level they contained a broad spectrum of organelles with a distribution characteristic of neuronal growth cones, including dense core vesicles, abundant smooth membrane cisternae, microtubules, and a filamentous network. The presence of channels capable of generating action potentials was revealed by intracellular microelectrode recording from the growth cone in the presence of locally applied tetraethylammonium (TEA). TEA appeared to block outward current channels that could effectively shunt inward current activated by depolarization. Action potentials elicited by depolarizing current in the presence of TEA could be blocked reversibly by Cd2+, a specific blocker of Ca channels. These action potentials were often followed by a long after‐hyperpolarization lasting hundreds of milliseconds. This after‐hyperpolarization was similar to that recorded in the cell body of PC12 cells where it appears to be mediated by Ca‐activated K current. Single channel recording from outside‐out excised patches of membrane from the growth cones perfused with KF revealed the presence of voltage sensitive Na channels, Ca‐activated K channels, and K channels resembling delayed rectifier K channels. Macroscopic currents recorded from mechanically isolated growth cones in the “whole cone” configuration showed rapid inward currents at potentials ≥ ‐40 mV, followed by delayed outward currents at more positive potentials, a finding providing additional evidence for the presence of Na and K channels in growth cones.
Myelin basic protein‐responsive blood T lymphocytes in patients with multiple sclerosis
Authors: Hashim G.A. , Brewen M. 
Published: January 2005

AbstractPrevious studies from our laboratory showed the development of circulating T lymphocytes sensitized to myelin basic protein (MBP) in guinea pigs challenged with MBP. Also, lymphocytes sensitized to MBP were found in patients with multiple sclerosis (MS). In this report, we describe the kinetics of MBP‐sensitized lymphocytes in a longitudinal study (140–316 days) of seven MS patients using the MBP‐stimulated active rosette‐forming T cell assay (MBP‐ARFC). Expressed as the ratio of MBP‐ARFC over ARFC (early and 37°C stable rosette‐forming T lymphocytes without added antigen), the results show a considerable degree of variation in the levels of MBP‐ARFC. Although the levels of ARFC during the study period were relatively unchanged for each patient, increases in the MBP‐ARFC/ARFC ratios were associated with the development of neurological symptoms of disease. The results of this study demonstrate the development of T‐cell‐mediated immunity to MBP in patients with MS. Detection of MBP‐sensitive cells was possible during the course of the disease. The level of sensitivity was influenced by the clinical status, degree of neurological deficit, and particular treatment course.
The effect of nerve lesions on the inflammatory response to injury
Authors: Helme R.D. , Andrews P.V. 
Published: January 2005

AbstractThe effects of surgical denervation, capsaicin, and 6‐Hydroxydopamine pretreatment on the inflammatory response to thermal injury have been investigated in the rat. Surgical denervation and capsaicin pretreatment reduced the cellular and exudative reactions to the injury. 6‐Hydroxydopamine appeared to have a selective effect on the exudative reaction only. The effects of surgical denervation are partly explained by local and systemic effects of the procedure.
The effect of inhibiting brain thromboxane biosynthesis on pentylenetetrazole‐induced seizure threshold
Authors: McGinley S. , Centra M. , Lysz T.W. 
Published: January 2005

AbstractThe effect of inhibiting endogenous brain thromboxane (TXB2) on pentylenetetrazole‐induced seizures was studied using the thromboxane synthetase inhibitors OKY‐1581 (20 mg/kg) and UK 38,485 (50 mg/kg). Both compounds selectively decreased (> 90%) TXB2 production in brain measured after 2 min of convulsive activity but had no effect on brain PGE2, PGF2α, or 6‐keto‐PGF1α No effect of these agents on the tonic seizure threshold was observed, whereas 10 mg/kg ip indomethacin, an agent which inhibits both TXB2 and prostaglandin production, reduced the tonic seizure threshold from 78 ± 2.6 mg/kg in controls to 62 ± 3.7 mg/kg. Thus, this study concludes that the availability of TXB2 with convulsant activity is unlikely to be a factor in altering tonic seizure activity observed with indomethacin.
Response of abdominal muscle to graded mechanical loads
Authors: Baker J.P. , Frazier D.T. 
Published: January 2005

AbstractAbdominal muscle electromyograms were monitored in response to graded mechanical loads added to either inspiration or expiration in anesthetized cats. The surgical preparation, the apparatus, and the levels of loads applied (resistive, tracheal occlusion, and continuous positive pressure) were matched with those employed in our previous study on medullary expiratory neurons [Baker et al, 1979]. Although expiratory neuron firing was significantly increased by each of three graded levels of expiratory resistive loads, abdominal muscles were activated in only about 50% of the animals exposed to the highest‐level resistive load. The smaller resistive loads failed to elicit any discernible abdominal muscle activity. These findings suggest that the lower motor neurons have a higher threshold for activation than the medullary neurons. Recruitment of medullary expiratory neurons and integration of synaptic input at the spinal level must play important roles in the response to expiratory loading. Abdominal muscles did not respond to mechanical loading during inspiration. Bilateral cervical vagotomy eliminated the abdominal muscle responses to expiratory loads.
Prenatal and postnatal hypothyroidism abolishes lesion‐induced noradrenergic sprouting in the adult rat
Authors: Gottesfeld Z. , Butler I. J. , Findley W. E. 
Published: January 2005

AbstractThe effects of altered thyroid states on regeneration in the nervous system are equivocal. This work was undertaken to examine the influence of propylthiouracil‐induced (PTU‐induced) pre‐ and postnatal hypothyroidism on collateral sprouting of noradrenergic (NA) axons in the habenula (Hb), following lesions in the stria medullaris (SM) of the adult rat. Ten pregnant dams were divided into control and PTU‐treated groups. Control rats had free access to food and water and the hypothyroid group received, in addition, 0.05% (w/v) of PTU in their drinking water, beginning on day 12 of gestation and continuing post partum through lactation until the offspring were weaned at age 22 days. The pregnant dams received, in addition, daily injections of thyroxine (25 μg/kg, ip) and only male pups were used in the study. At weaning he pups were removed from the dams and placed in cages with free access to food and water. The hypothyroid offspring received 0.05% (w/v) PTU in the drinking water until sacrificed at 10 weeks of age. At 6 weeks, some rats in each group received bilateral lesions in the SM and the remainder were sham‐operated. All rats were sacrificed 4 weeks after operation. Thus, four groups wre formed: (1) control/sham, (2) control/lesion, (3) PTU/sham, (4) PTU/lesion. Sprouting of NA fibers in discrete regions of the Hb was identified by norepinephrine (NE) levels and by fluorescence histochemistry. Blood levels of thyroid stimulating hormone (TSH) were determined. The results show that pre‐ and postnatal induced chronic hypothyroidism abolished NA sprouing in the partially deafferented Hb. Furthermore, lesions of the SM resulted in a marked decrease in serum TSH levels.
Intraocular kainic acid injection suppresses fast axonal transport in the developing rat optic nerve
Authors: Riccio R. V. , Calle R. P. , Matthews M. A. 
Published: January 2005

AbstractA single intraocular injection of 1 or 3 nmol kainic acid (KA) into the right eye of rats aged 5 days postnatal (5 dpn) significantly reduced the incorporation of 3H‐proline into retinal proteins and suppressed the amount of 3H‐proline‐labeled materials fast axonally transported in the optic nerve for at least 2 weeks thereafter. Intraocular KA injection within this dose range had no adverse effect on the optic axon population compared to normal nerves determined at 21 dpn; however, doses above 3 nmol (i.e., 6 nmol) caused significant axonal degeneration. Although partially recovered by 21 dpn this effect of KA on protein synthesis and axonal transport suggests that, as in the adult, retinal ganglion cells are also KA‐sensitive during postnatal development.
Modulation of immunoactive levels of DSIP and blood‐brain barrier permeability by lighting and diurnal rhythm
Authors: Banks W. A. , Kastin A. J. , Selznick J. K. 
Published: January 2005

AbstractThe brain and plasma levels of immunoactive delta sleep‐inducing peptide (DSIP) as well as the permeability of the blood‐brain barrier (BBB) to radioiodinated N‐Tyr‐DSIP (125I‐DSIP) were measured at 0400, 0800, 1200, 1600, 2000, and 2400 hr in rats in a normal 12‐hr‐light/12‐hr‐dark cycle and at 0800 in rats in constant light or constant dark. Both brain and blood levels of immunoactivity showed statistically significant dirunal changes, whereas the measurement of BBB permeability varied in a regular fashion over time without the changes reaching statistical significance. Immunoactive levels of DSIP in both plasma and the brain were higher and permeability of the BBB to 125I‐DSIP increased in both the constant light and especially the constant dark groups incomparison with the cycled 0800 group. Diurnal variations continued to occur in the blood levels of immunoactive DSIP in the constant dark animals. Studies with radioiodinated serum albumin (RISA) showed that these findings did not result from a change in brain hemodynamics. Immunoactive levels of DSIP in the plasma correlated with brain immunoactive levels and with BBB permeability to 125I‐DSIP. The increase in penetration of 125I‐DSIP into the brain that occurred with changes in the lighting cycle appeared to be magnified by pre‐treatment with aluminum. The results show interrelationships among various aspects of the neuroendocrine axis for DSIP and their modulation by physiological factors.
Cerebral citric acid cycle enzymes in methionine sulfoximine toxicity
Authors: Ratnakumari L. , Subbalakshmi G. Y. C. V. , Murthy Ch. R. K. 
Published: January 2005

AbstractThe activity levels of pyruvate dehydrogenase, enzymes of the citric acid cycle, aspartate and alanine aminotransferases, and NADP+ ‐isocitrate dehydrogenase were determined in the cerebral cortex, cerebellum, brain stem, corpus striatum, hippocampus, and midbrain regions of normal rats and rats injected with acute and subacute doses of methionine sulfoximine (MSI). In both conditions there was an elevation in the activities of pyruvate dehydrogenase and all the enzymes of the citric acid cycle except malate dehydrogenase, whereas the activities of aminotransferases and NADP+ ‐isocitrate dehydrogenase were suppressed in all the cerebral regions. It is suggested that the operational rates of the citric acid cycle would be enhanced in MSI‐induced hyperammonemia and that there might be a derangement in the transport of reducing equivalents across mitochondrial membranes. It has been suggested that the convulsant action of the drug is due to its effects on ionic gradients and may not be due to depletion of α‐ketoglutarate from the citric acid cycle.
Hypotaurine uptake by the retina
Authors: Pasantes‐Morales H. , Morán J. , Fellman J. H. 
Published: January 2005

AbstractA study of the transport of 3H‐hypotaurine by rat retina has been carried out. The process is markedly sodium and temperature dependent. Kinetic analysis of the data revealed two values for the affinity constant (K) of 4.91 μM and 1,071.3 μM. Some related and unrelated amino acids were examined as competitive inhibitors of 3H‐hypotaurine transport. Only GABA and β‐alanine exhibited appreciable inhibitory activity. Taurine, glycine, and guanidine ethane sulfonate were not inhibitors.3H‐hypotaurine uptake was similarly distributed in the retinal subcellular fractions P1 and P2. The active uptake of 3H‐Hypotaurine by retinas of the rat and other species including chick and frog was studied and compared to cerebral cortex slices. The chick retina was similar to the rat in its capacity to transport hypotaurine whereas frog exhibited fourfold less activity. Slices of cerebral cortex from rat and chick exhibited hypotaurine uptake but again the magnitude of the transport was three to fourfold less than in the comparative retinas.
The synaptic form of acetylcholinesterase binds to cell‐surface heparan sulfate proteoglycans
Authors: Brandan E. , Inestrosa N. C. 
Published: January 2005

AbstractWe have previously communicated that heparan sulfate and heparin released 16S acetylcholinesterase (AChE) from cholinergic synapses. These experiments suggest that heparan‐like molecules are involved in the anchorage of AChE to the neuromuscular junction. In order to prove the in vivo interaction between the 16S AChE and heparan sulfate residues, the binding of exogenously added 16S enzyme to intact cells rich in cell‐surface heparan sulfate proteoglycans was examined; 16S AChE form was shown to bind to intact endothelial cells in a specific, time‐dependent, saturabel fashion. A single class of binding sites was involved and at saturation around 2.52 × 1011 molecules of 16S AChE/cm2 were bound. Fifty percent of the binding of the 16S AChE was blocked by heparan sulfate, heparin, or previous treatment of the cell with heparitinase. The binding was reversed by exogenous heparin, but not by chondroitin sulfate or hyaluronic acid. Our results demonstrate that the synaptic form of AChE binds to heparan sulfate proteoglycans on the surface of the cell.
Pharmacological identification of retinal cells releasing taurine by light stimulation
Authors: Salazar P. , Quesada O. , Campomanes M. A. , Morán J. , Pasantes‐Morales H. 
Published: January 2005

AbstractThe effect of drugs blocking synaptic activity at different retinal levels was examined in this study, in an attempt to identify the origin of the light‐stimulated release of 3H‐taurine from the chick retina. It was determined by autoradiography that the chick retina accumulates taurine in photoreceptors, in cells from the inner nuclear layer, and in processes of the inner plexiform layer. All these are possible sites for the release of taurine upon illumination. To discriminate among these possibilities, the effects of aspartate, tetrodotoxin, strychnine, picrotoxin, chlorpromazine, tubocurarine, atropine, glutamate diethyl esther, α‐amino adipate and 2‐amino‐4‐phosphonobutyrate were studied. Aspartate (10 mM), which is known to eliminate the light response of cells postsynaptic to photoreceptors, induced a marked increase of 150% in the resting efflux of 3H‐taurine but did not decrease significantly the light‐stimulated release. Tetrodotoxin, which blocks amacrine cell responses, decreased 3H‐taurine release stimulated by light by less than 20%. The efflux of taurine was unaffected by strychnine, pictrotoxin, tubocurarine, atropine, chlorpromazine, and 2‐amino‐4‐phosphonobutyrate, whereas it was increased by glutamate diethyl esther and α‐amino adipate. These results, all together, point to photoreceptors as the cells releasing 3H‐taurine in response to light.
Antigen‐specific adherence of antibody‐producing hybridoma cells: Application to neural and nonneural antigens
Authors: Najbauer J. , Tigyi G. J. , Nemeth P. 
Published: January 2005

AbstractAntibody‐producing hybridoma cells specifically bind to microgram quantities of antigen molecules adsorbed onto the surface of plastic microtiter plates. The binding of hybridoma cells to nonantigen is optimally below 5%, similar binding of non‐antibody‐producing cells is 4–7%, compared to the binding of the hybridomas to their antigen. There is a difference in the kinetics of binding hybridomas to antigen compared to nonantigen. The number of bound cells depends on the amount, i.e., the surface density, of the antigen molecules and shows typical saturation effects.Preincubation of hybridomas with excess free antigen and saturation of the antibody binding site on the surface with the hybridoma‐produced antibody reduces binding of the hybridoma cells to the antigen. Treatment of cells with trypsin reduces binding to antigen‐coated plastic surfaces. Drugs such as sodium azide, cytochalasin B, colchicine, vinpocetine, and vincristine sulfate reduce binding to the antigen. Hybridoma cells adhering to the antigen produce more antibody than nonadhering cells.The results reported in this paper show that antigen molecules adsorbed to include a plastic surface and hybridoma cells interact specifically. This system forms a suitable model to study the interaction of antigen with antigen‐specific cells and may be useful as a separation method for specific antibody‐producing cells.
Delayed phosphorylation of the largest neurofilament protein in rat optic nerve development
Authors: Dahl D. , Crosby C. J. , Gardner E. E. , Bignami A. 
Published: January 2005

AbstractMonoclonal antibodies selectively reacting with the high molecular weight neurofilament proteins (NF 150K and NF 200K) on immunoblots of bovine spinal cord extracts were obtained upon immunization of mice with chicken brain antigen and with highly purified NF 150K or NF 200K isolated from bovine spinal cord by anion exchange chromatography. Antibodies reacting with NF 200K or with both NF 150K and NF 200K were selected for this study. The antibodies were screened on immunoblots for reactivity with phosphorylated epitopes by dilution of the supernatants in sodium potassium phosphate as well as by treatment of nitrocellulose transfers with alkaline phosphatase. Abolishment of staining under these conditions was taken as evidence of reactivity with phosphorylated epitopes. With phosphate/phosphatase‐sensitive antibodies, NF 200K immunoreactivity was a late event in rat optic nerve development. It was first observed at day 18 on immunoblots of sodium dodecyl sulfate extracts analyzed by gel electrophoresis. Conversely, with phosphate/phosphatase‐insensitive antibodies, NF 200K immunoreactivity was already present on day 10, the earliest age in this study. With one monoclonal reacting with phosphorylated NF 150K and NF 200K, NF 150K immunoreactivity was already present on day 10. It is proposed that NF 200K expression precedes NF 200K phosphorylation in development.
Cellular localization of proglucagon/glucagon‐like peptide I messenger RNAs in rat brain
Authors: Han V.K.M. , Hynes M.A. , Jin C. , Towle A.C. , Lauder J.M. , Lund P.K. 
Published: January 2005

AbstractTechniques of in situ hybridization histochemistry, Northern blot hybridization, and immunocytochemistry were used to investigate the biosynthesis of glucagonlike immunoreactants (GLIs) in rat brain. Cells in the nucleus tractus solitarius of the medulla oblongata of adult rat brain hybridized to a synthetic oligonucleotide probe (GLP‐I oligomer) corresponding to nucleotide sequences in pancreatic proglucagon mRNA encoding glucagon‐like peptide I (GLP‐I), and stained with antisera specific for two antigenic determinants of pancreatic proglucagon, glucagon, and GLP‐I. These data suggest that there is de novo synthesis of proglucagon in cells of the nucleus tractus solitarius via expression of a proglucagon mRNA similar to that produced in pancreas. Previous studies have shown that cells in hypothalamus stain with GLP‐I antisera, but not with glucagon antisera. However, cells in the hypothalamus did not hybridize with the GLP‐I oligomer and may therefore produce a GLP‐I immunoreactant that is encoded by a mRNA different from the pancreatic proglucagon‐mRNA‐encoding glucagon and GLP‐I. Northern blot hybridizations with a cDNA probe encoding the entire pancreatic proglucagon sequence did not detect proglucagon/GLP‐I mRNAs in polyadenylated RNAs (Poly A RNA) from adult rat brainstem and hypothalamus, probably because of their low abundance. Poly A RNAs from fetal rat brain, however, contained two mRNAs that hybridized to the proglucagon cDNA probe. One mRNA of 1,300 bases is the same size as pancreatic proglucagon mRNA. The second mRNA of 1,500 bases may encode the GLP‐I immunoreactant detected in the hypothalamus of adult rat brain. The presence of neurons with glucagon and glucagon‐like peptides in the nucleus tractus solitarius suggests a role of these peptides in gustatory and/or cardiopulmonary control.