bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of calcium in the initiation of fast axonal transport of protein: Effects of divalent cations
Authors: Hammerschlag Richard , Bakhit Charles , Chiu Arlene Y. , Dravid Anant R. 
Published: January 2005

AbstractFast axonal transport of [3H]protein has been examined in bullfrog primary afferent neurons incubated in media supplemented with divalent cations that can act as agonists or antagonists of calcium ions. Incubation in calcium‐free medium (CFM) had no effect on the rate of transport, but reduced the amount of transported [3H]protein by 40–60% relative to transport in the contralateral preparation maintained in normal medium. Preparations incubated in CFM supplemented with 1.8 mM SrCl2 (equimolar to the CaCl2 concentration in normal medium) carried out transport at control levels. Incubation conditions in which primary afferent somata were exposed to the Sr2+‐medium while nerve trunks were maintained in CFM also supported normal transport. By contrast, selective exposure of nerve trunks to Sr2+‐medium, and somata to CFM resulted in a reduced level of transport similar to that observed when the whole preparation was incubated in CFM. The depression of transport resulting from incubation in CFM was shown to be reversible when preparations were transferred from CFM to either Sr2+‐supplemented CFM or to normal medium. By contrast to the effects of Sr2+, Ba2+ (up to 18 mM) did not substitute for Ca2+ in the transport process. When normal medium was supplemented with calciumantagonist cations, the amount of transport was depressed (Co2+ > Mn2+ >> Mg2+), with no concomitant effect on the rate of transport. Results of studies with Co2+, as well as those with Sr2+, suggest that a major locus of action of these cations is within the neuronal soma at a step subsequent to protein synthesis, and prior to the onset of protein translocation via the transport system. Thus, it is inferred that these divalent cations affect a calcium‐dependent step that occurs during the initiation phase of fast axonal transport.
Computer‐assisted analysis of particulate axoplasmic flow in organized CNS tissue cultures
Authors: Leestma Jan E. , Freeman Stephennie S. 
Published: January 2005

AbstractUsing organized nervous system tissue cultures of embryonic mouse spinal cord, time‐lapse motion pictures of intra‐axonal particle movements were made using Nomarski optics. The paths of 272 particles were followed and analyzed using digital computer methods. Particles had a bidirectional saltatory motility with net anterograde and retrograde velocities which were shown to be the same (about 1 micron per second). When anterograde moving and retrograde moving particles were analyzed separately for anterograde and retrograde saltations, the velocities of saltations in the direction of net movement were found to be 1.5 times greater than saltations against the direction of net movement. These differences were statistically significant. In addition, it was shown that there were regions within the axon where variations in particle motion were similar from particle to particle as they passed, and that more disturbed motion was found to occur near intra‐axonal objects which were judged to be mitochondria. No decrease of particle velocity was noted in regions away from mitochondria nor was an increase in velocity noted near them. Computer‐drawn particle plots illustrate the various facets of particle motion.
Distribution of 45Ca in the superior cervical ganglion of the cat
Authors: Robinson Joseph D. , Kabela Emilio 
Published: January 2005

AbstractSuperior cervical ganglia isolated from immature cats accumulated 0.9 ng atoms of 45Ca per mg wet weight during 10‐min incubations at 37°C; when expressed as an equivalent volume of medium the accumulation was four times the uptake of 3H‐inulin. Orthodromic stimulation of the ganglia doubled 45Ca accumulation, whereas excitation with 50 mM KCl, 5 mM glutamate, or antidromic stimulation increased accumulation by one‐half. Hexamethonium reduced the increment in 45Ca accumulation due to orthodromic stimulation only, but another ganglionic blocking agent, tetraethylammonium, did not reduce accumulation in any case. Both agents blocked ganglionic transmission monitored electrophysiologically. To resolve this discrepancy, and to approach the localization of 45Ca within the ganglia, the efflux of previously accumulated 45Ca was examined. The data could be fitted by an equation incorporating the sum of three exponentials, representing a rapidly exchanging compartment plus two more slowly exchanging ones. The latter two appeared to reflect the pre‐ and postganglionic elements in the ganglia: 45Ca content of the “preganglionic” compartment was increased by orthodromic but not by antidromic stimulation, and was not decreased by either blocking agent; conversely, 45Ca content of the “postganglionic” compartment was increased by both orthodromic and antidromic stimulation, and was decreased by both blocking agents after orthodromic stimulation. The lack of effect of tetraethylammonium on the whole ganglion resulted from an increase in “preganglionic” accumulation that offset the “postganglionic” decrease. After preganglionic denervation, the 45Ca content of the “preganglionic” compartment was reduced by two‐thirds, while the 45Ca content of the “postganglionic” compartment was unchanged. Chemical stimulation increased 45Ca accumulation in both compartments. Diphenylhydantoin, 0.1 mM, decreased the increment in 45Ca accumulation due to electrical stimulation and to 50 mM KCl; this inhibition occurred in the “preganglionic” compartment (and perhaps also in the “postganglionic”), and was accompanied by an increased efflux of 45Ca.
Protein composition of cockroach muscles: Identification of candidate recognition macromolecules
Authors: Denburg Jeffrey L. 
Published: January 2005

AbstractThe protein composition of each of the coxal depressor muscles from the leg of the cockroach, Periplaneta americana, was analyzed by SDS polyacrylamide gel electrophoresis. The proteins from each muscle were fractionated according to their extractability in Ringer's solution, 1% Triton X‐100 and 1% SDS. The gel protein patterns of the fractionated muscles revealed some biochemical differences that could be correlated with mechanical and ultrastructural differences observed among the muscles. In addition, proteins were detected that were considered to be candidate recognition macromolecules that are responsible for the intercellular recognition process that enables regenerating motor neurons to specifically recognize and make stable, functional connections only with the muscles to which they were originally connected. The major evidence for this identification of candidate recognition macromolecules was that their presence in the muscle could best be correlated with innervation by an identified motor neuron. In addition, these proteins remain present in denervated muscles for at least as long as it takes for the original innervation pattern to be reformed by the regenerating motor neurons.
Uptake of radiolabeled glucose analogues by organotypic cerebellar cultures
Authors: Renkawek K. , Spatz M. , Murray M. R. , Klatzo I. 
Published: January 2005

AbstractPermeability of brain cells to radiolabeled glucose analogues with sucrose or inulin or L‐glucose was studied in the living, intact state of the organotypic cerebellar cultures. In vitro uptake of 3H 3‐O‐methyl D‐glucose and 3H 2‐deoxy‐D‐glucose exhibited saturation kinetics with increasing substrate concentrations. Each of the labeled sugars uptake could be self‐inhibited in the presence of unlabeled (cold) substrate and cross‐inhibited with cold glucose or xylose or phlorizin present in the incubating medium. The uptake was Na‐independent and stereo‐specific for D‐form.
Anoxic block and recovery of axoplasmic transport and electrical excitability of nerve
Authors: Leone J. , Ochs S. 
Published: January 2005

AbstractAxoplasmic transport of cat sciatic nerves was studied in vitro in a chamber in which maximal α action potentials could also be elicited. After initiation of N2 anoxia, electrical responses fell to zero at an average time of 22 min. A shorter time to zero of 11 min was seen during a second period of anoxia.A good recovery of both action potential responses and axoplasmic transport occurs after a period of anoxia lasting 1–1.5 hr. An apparent failure of recovery of axoplasmic transport was seen after 2 hr of anoxia with a good recovery of electrical responses. Axoplasmic transport tended to return toward normal when more time was allowed for recovery after anoxia. An adequate supply of ∼P was shown to be present by measurement of ATP and creatine phosphate levels. The delay in recovery of transport thus signifies a failure of utilization of ∼P by the transport mechanism.Longer periods of anoxia and recovery were limited in vitro and for this reason, ischemic anoxia was produced in vivo. Blood pressure cuffs were placed on the upper thigh of cats and maintained for times of 1–8 hr at pressures of 300–310 mm Hg. Then, recovery times up to 7 days were allowed. It was shown that axoplasmic transport could gradually recovery after an anoxia lasting up to 6–7 hr if sufficient recovery times were allowed.A possible explanation for the delay in the recovery of axoplasmic transport and the disassociation in the earlier recovery of electrical responses as against the recovery of transport was discussed.
Synaptic connections and functional organization in Aplysia buccal ganglia
Authors: Fiore L. , Meunier J.‐M. 
Published: January 2005

AbstractThe buccal ganglion of Aplysia contains three morpho‐functional groups (A, B, and C) of large cells and two groups (s1 and s2) of small cells. The A cells evoke monosynaptic IPSPs in the B cells. We found that s1 cells can evoke large EPSPs in the A cells, IEPSPs in the B cells, and EIIPSPs in the C cells; several s1 cells are able to evoke all three types of responses. Many s2 cells can evoke these same responses, but only in the A and B cells. Furthermore, the s cells can evoke depolarizing PSPs in other s cells; this relation is often reciprocal. All these responses may also be contralateral. Their monosynaptic nature is shown by the consistent 1:1 relationship with the presynaptic spike, and also by the effects of intracellular tetraethylammonium and of high Mg2+ concentration in the bathing medium. D‐tubocurarine reversibly suppresses the I phase of the IEPSP evoked by the s cells in the B cells. All the responses evoked by the s cells undergo depression with repetition.The network formed by all these relations is outlined, and a double relationship proposed between s cells and B cells. By electrophysiological tracing of axonal pathways it is shown that the A cells send axons into the 3rd buccal nerve, the B cells into the 2nd and/or 3rd buccal nerve and in two cases into the redular nerve, and the C cells into the gastro‐oesophageal nerve. Spontaneous synaptic activity of the buccal neurons appears to be formed mostly by the described PSPs. Spontaneous firing inside the isolated ganglion corresponds well to the alternate pattern of muscular contractions of the buccal mass.
The structure and function of serially homologous leg motor neurons in the locust. I. Anatomy
Authors: Wilson John A. 
Published: January 2005

AbstractTwenty‐one prothoracic and 17 mesothoracic motor neurons innervating leg muscles have been identified physiologically and subsequently injected with dye from a microelectrode. A tract containing the primary neurites of motor neurons innervating the retractor unquis, levator and depressor tarsus, flexor tibiae, and reductor femora is described. All motor neurons studied have regions in which their dendritic branches overlap with those of other leg motor neurons. Identified, serially homologous motor neurons in the three thoracic ganglia were found to have: (1) cell bodies at similar locations and morphologically similar primary neurites (e.g., flexor tibiae motor neurons), (2) cell bodies at different locations in each ganglion and morphologically different primary neurites in each ganglion (e.g., fast retractor unguis motor neurons), or (3) cell bodies at similar locations and morphologically similar primary neurites but with a functional switch in one ganglion relative to the function of the neurons in the other two ganglia. As an example of the latter, the morphology of the metathoracic slow extensor tibiae (SETi) motor neurons was similar to that of pro‐and mesothoracic fast extensortibiae (FETi) motor neurons. Similarly the metathoracic FETi bears a striking resemblance to the pro‐ and the mesothoracic SETi. It is proposed that in the metathoracic ganglion the two extensor tibiae motor neurons have switched functions while retaining similar morphologies relative to the structure and function of their pro‐ and mesothoracic serial homologues.
The intra‐axonal transport of acetylcholine and cholinergic enzymes in rat sciatic nerve during regeneration after various types of axonal trauma
Authors: Heiwall P.‐O. , Dahlström A. , Larsson P.‐A. , Bööj S. 
Published: January 2005

AbstractThe proximo‐distal intra‐axonal transport of acetylcholine (ACh) and cholinergic enzymes (choline acetyltransferase, CAT, and ACh‐esterase, AChE) in rat regenerating sciatic nerve was studied by accumulation technique. Four types of axonal trauma were performed: freezing with solid CO2, crushing, ligating the nerve with remaining tight silk ligature, and cutting the nerve. Normal and sham‐operated rats were used as controls. One to twenty‐nine days later, the nerves were crushed about 15 mm proximal to the trauma. The nerve segment proximal to this crush was dissected out 12 hr later and assayed for ACh‐content and enzyme activities. The increase in this segment 12 hr after crushing was taken as an indication of proximo‐distal transport in the regenerating nerves. ACh transport did not seem to vary during regeneration as compared to controls. In contrast, the transport of both CAT and AChE was initially markedly depressed. Towards the end of the observation period (29 days), a recovery of CAT‐transport occurred in all groups. Recovery of AChE‐transport was marked in the freeze and crush groups. In the cut group no recovery was seen and in the ligated group only a small recovery occurred. Thus, in the nerves where regeneration was facilitated by the presence of intact connective tissue sheaths (freezing and crushing) recovery of transport occurred earlier than in cut or ligated nerves.
Dopamine β‐hydroxylase distribution in density gradients: Physiological and artefactual implications
Authors: Klein Richard L. , Thureson‐Klein Åsa K. , Yen Shu‐Hui Chen , Baggett Jack McC. , Gasparis Milton S. , Kirksey Donny F. 
Published: January 2005

AbstractKnowledge of the vesicular origin of circulating dopamine β‐hydroxylase (DβH) is indispensable for any attempts to explain the parallelism or lack of it between circulating enzyme and catecholamines as they may relate to physiological stress, forms of hypertension, neurological disorders, and the response to pharmacological agents. The present study represents an effort to evaluate and to place in proper perspective data based on the DβH activity found in the region of the light vesicle peak of noradrenaline (NA), which is used as a quantitative measure of a population of small terminal vesicles.Distributions of vesicles and subvesicular components are compared with DβH and NA in sucrose‐D2O density gradients used to prepare relatively pure fractions of large dense cored vesicles (LDV) from bovine splenic nerve. Although NA in sedimentable particles of the light vesicle peak is likely to be a valid measure of a small vesicle population, the following is demonstrated: (1) A substantial fraction (25%–37%) of the total sedimentable DβH acitivity can be proven to distribute in the region of the light vesicle peak from a tissue with an insignificant small vesicle population. Based on studies of vesicles from sequential nerve segments, this enzyme activity probably corresponds to a population of “immature” LDV which are undergoing axoplasmic transport and have not synthesized their full complement of transmitter. (2) Physical lysis which depletes the matrix of LDV causes redistribution of DβH activity from the heavy vesicle peak into the region of the light vesicle peak. Analogously, DβH associated with exocytosed LDV and retrograde transport particles is also likely to contaminate the region of the light vesicle peak. (3) Based on available data, it can be calculated that each small dense cored vesicle could contain only 0.1–0.5 molecules of DβH and that a contamination of only 0.016% LDV can account for all of the DβH reported to occur in the light vesicle peak of normal rat vas deferens preparations.
The morphology and coupling of Aplysia bag cells within the abdominal ganglion and in cell culture
Authors: Kaczmarek L. K. , Finbow M. , Revel J. P. , Strumwasser F. 
Published: January 2005

AbstractThe bag cells in the abdominal ganglion of Aplysia californica control egglaying behavior by releasing a polypeptide (ELH) during an afterdischarge of synchronous action potentials. We have used intracellular injection of Lucifer Yellow to study the morphology and interconnections of the bag cells. These neurosecretory cells are typically multipolar and their processes extend in all directions out from the bag cell clusters into the surrounding connective tissue, where they branch in a complex manner. In some of the dye injection experiments, dye transfer from the injected cell to neighboring cells was observed. Freeze fracture of the bag cell clusters and their surrounding connective tissue revealed numerous gap junctions on bag cell processes within the clusters as well as on more distal processes. We have also examined the morphology and coupling between bag cells in primary culture. As in the intact ganglion, bag cells in culture were found to be multipolar. All pairs of bag cells whose somata or processes had formed contacts in culture were electrically coupled. The strongest coupling was observed between pairs of cells whose somata appeared closely apposed. In these cases transfer of Lucifer Yellow between cells could also be observed. It is therefore likely that the synchrony of bag cell action potentials during a bag cell afterdischarge is a result of coupling between individual cells in the bag cell cluster.
Electrical and dye coupling in an identified group of neurons in a coelenterate
Authors: Spencer Andrew N. , Satterlie Richard A. 
Published: January 2005

AbstractA compressed network of “giant” neurons, lying within the inner nerve‐ring of the hydrozoan jellyfish Polyorchis, functions as the overall pattern generator and the motor neuron system for the subumbrellar swimming musculature. The neurons that form the network are all electrically coupled. The coupling is tight, so that action potentials and slow membrane‐potential oscillations are synchronous throughout the network. The fluorescent dye Lucifer Yellow CH passes throughout the network following iontophoretic injection into a single neuron. The sites of both current and dye passage are presumably the numerous gap junctions which are found where the giants run together. Based on the morphological identification of the giant network from the dye injections and ultrastructural studies, the electrophysiological data on the firing pattern and input–output relations of the network, and its position relative to other neurons in the inner nerve‐ring, the giant network can be considered an identified neuronal group.
The deutocerebrum of the cockroach Blaberus craniifer burm. Spatial organization of the sensory glomeruli
Authors: Chambille Irène , Masson Claudine , Rospars Jean Pierre 
Published: January 2005

AbstractThe objective of this work is to describe the glomerular organization of the deutocerebrum in Blaberus craniifer and to test the hypothesis that the glomeruli are identifiable. The problem is studied using the techniques of analytical geometry, i.e., by measuring the location of the glomeruli in cartesian coordinate systems. Computerized geometrical and statistical techniques are described for the three‐dimensional reconstruction and quantitative study of these brain structures. The invariance of the glomerular organization, and consequently the identifiability of the glomeruli, is based on three criteria: (1) the number of glomeruli per hemideutocerebrum (hDTC) is a constant (109); (2) the position of the glomeruli is symmetrical in the two sides of one individual and identical in the same side of two individuals, except for small local variations, (3) the dimensions of two positionally homologous glomeruli are statistically equal in the same and in different individuals, except for a macroglomerulus which is found only in the male. The causes of variability, from experimental and biological origin, are discussed and quantitatively evaluated. The interindividual biological variability, not ascribable to differences in size between brains, expressed as a 95% interval, is estimated to be 27 μm for the location of glomeruli and 12 μm for the diameter of glomeruli.
Characteristics of tetanic and post‐tetanic potentiation in the septohippocampal and hippocampal commissural systems in the acute rabbit
Authors: Stanley James C. , DeFrance Jon F. , Marchand James E. 
Published: January 2005

AbstractThe frequency characteristics of tetanic and post‐tetanic potentiation of the septohippocampal and hippocampal commissural systems were studied in the acute rabbit preparation. Glass micropipettes were employed to stimulate the medial septal (MSR) and contralateral CA1 (cCA1) regions. Extracellular postsynaptic potentials were recorded in the stratum radiatum and stratum oriens layers of dorsal CA1. Low frequencies of stimulation (2–12 Hz) and brief stimulus trains (7 or 16 stimuli) ensured that only short‐term effects appeared in the data. With MSR and cCA1 stimulation, tetanic potentiation became pronounced at 4 Hz, and plateaued at 6–8 Hz. Thus potentiation was found to be pronounced within the range of the rabbit hippocampal theta rhythm. No differences were found in the characteristics of potentiation evoked by stimulation of MSR and cCA1. Post‐tetanic potentiation lasting 6–12 sec was found. Again, potentiation characteristics did not depend on stimulus site, suggesting a common mechanism for the pathways studied. A two‐factor mechanism was proposed to account for the post‐tetanic potentiation data.
Slice preparation of rat medulla and pons maintained for five hours in vitro
Authors: Hinrichsen C. F. L. 
Published: January 2005

AbstractSlices of rat medulla and pons were incubated in bicarbonate‐buffered medium and their electrical activity was monitored for five hours with microelectrodes. The morphology of these slices was compared with that of the same region of rats of the same age using prior perfusion or immersion in fixatives before incubation. Many neurons in incubated slices show shrinkage necrosis (apoptosis) but not dilatation of the endoplasmic reticulum seen in most neurons fixed immediately after slicing. In incubated slices, some processes but not somata of glia appeared swollen: to a lesser extent some dendritic and axonal processes were swollen. Glia showed no cytoplasmic reaction after five hours to indicate that they might phagocytose damaged tissue components. Synapses appeared morphologically normal after the period of incubation and there was an apparent increase in numbers of profiles resembling growth cones.