bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vrms/T quantitation: usefulness in patients with neuropathies
Authors: Fisher Morris A. , Itkin Arthur 
Published: January 2005

AbstractThis study evaluates the sensitivity of root mean square voltage (Vrms)/turns (T) ratios in neuropathies. Data were recorded with concentric needle electrodes from the biceps brachii, first dorsal interosseous, tibialis anterior, and calf muscles. Recordings were analyzed from 35 normal subjects as well as 24 consecutive patients referred for evaluation of neuropathic disorders. Direct tension measurements were not required. Reasoning from studies in normal subjects in which Vrms/T values were related to measurements of relative tension, the data were recorded during strong muscle contractions of less than 80% of maximum tension as monitored by mean amplitude values. For all 5 muscles, mean Vrms/T values ≥1.0 claculated from four separate needle sites were significantly more frequent in the patients than controls (p < 0.012–0.0001). There were 13 muscles in which relevant conduction studies were abnormal and Vrms/T ≥1.0 were the only abnormality of the needle EMG examination. In addition, a Vrms/T of ≥1.0 was present in 10/14 muscles in which abnormalities might have been expected but where other needle EMG parameters were unremarkable and relevant nerve conductions normal. This study indicates that Vrms/T measurements can add meaningfully to the electrodiagnostic evaluation of neurogenic dysfunction. © 1995 John Wiley & Sons, Inc.
Insulinlike growth factor gene expression in rat muscle during reinnervation
Authors: Glazner Gordon W. , Ishii Douglas N. 
Published: January 2005

AbstractBecause insulinlike growth factors (IGFs) support motor axon regeneration, we tested whether the IGF genes expressed during the development of neuromuscular synapses are reexpressed in adult rat muscles during synapse regeneration. Following sciatic nerve crush, IGF‐II mRNAs per poly(A)+ RNA, as well as per poly(A)+ RNA per milligram muscle, were significantaly up‐regulated in denervated relative to intact contralateral gastrocnemius muscles. IGF‐II mRNAs were downregulated after the reestablishment of functional neuromuscular synapses, but remained up‐regulated when nerves were transected to prevent the reestablishment of synapses. These data are consistent with a model in which the IGF‐II gene is reexpressed during regeneration due to loss of nerve‐dependent feedback inhibition. There was a slight but significant increase in IGF‐I mRNAs per poly(A)+ RNA per milligram muscle, probably as a consequence of muscle atrophy. These results show that IGF‐II gene expression is up‐regulated in muscle during the reestablishment of synapses. © 1995 John Wiley & Sons, Inc.
Manganese‐enhanced magnetic resonance imaging (MEMRI)
Authors: Koretsky Alan P. , Silva Afonso C. 
Published: January 2005

AbstractManganese ion (Mn2+) is an essential metal that participates as a cofactor in a number of critical biological functions, such as electron transport, detoxification of free radicals and synthesis of neurotransmitters. Mn2+ can enter excitable cells using some of the same transport systems as Ca2+ and it can bind to a number of intracellular sites because it has high affinity for Ca2+ and Mg2+ binding sites on proteins and nucleic acids. Paramagnetic forms of manganese ions are potent MRI relaxation agents. Indeed, Mn2+ was the first contrast agent proposed for use in MRI. Recently, there has been renewed interest in combining the strong MRI relaxation effects of Mn2+ with its unique biology, in order to further expand the already broad assortment of useful information that can be measured by MRI. Such an approach has been continuously developed in the past several years to provide unique tissue contrast, to assess tissue viability, to act as a surrogate marker of calcium influx into cells and to trace neuronal connections. This special issue of NMR in Biomedicine on manganese‐enhanced MRI (MEMRI) is aimed at providing the readers of this journal with an extensive review of some of the most prominent applications of MEMRI in biological systems. Written by several of the leaders in the field, the reviews and original research articles featured in this special issue are likely to offer an exciting and inspiring view of the broad range of applications of MEMRI. Copyright © 2004 John Wiley & Sons, Ltd.
In vivo, trans‐synaptic tract‐tracing utilizing manganese‐enhanced magnetic resonance imaging (MEMRI)
Authors: Pautler Robia G. 
Published: January 2005

AbstractIt is well established that manganese ion (Mn2+) can access neurons through voltage‐gated calcium (Ca2+) channels. Based upon this fundamental principle, Mn2+ has long been used in biomedical research as an indicator of Ca2+ influx in conjunction with fluorescent microscopy. Additionally, after entry into neurons, Mn2+ is transported down axons via microtubule based fast axonal transport. Furthermore, Mn2+ is paramagnetic, resulting in a shortening of the spin‐lattice relaxation time‐constant, T1, which yields positive contrast enhancement in T1‐weighted MRI images, specific to tissues where the ion has accumulated. Manganese‐enhanced MRI (MEMRI) utilizes a combination of these properties of Mn2+ to trace neuronal pathways in an MRI‐detectable manner. The focus of this review will detail some of the current MEMRI tract‐tracing methodologies in mice and non‐human primates as well as biological applications of MEMRI tract‐tracing. Copyright © 2004 John Wiley & Sons, Ltd.
Biochemically differentiated clonal human glial cells in tissue culture
Authors: Lightbody J. , Pfeiffer S. E. , Kornblith P. L. , Herschman H. 
Published: January 2005

AbstractA clonal line of astrocytes (designated CHB) derived from a brain tumor of human origin has been established in tissue culture. This cell line is capable of synthesizing an acid protein unique to the nervous system (S100‐protein). The S100‐protein synthesized by CHB cells is immunologically indistinguishable (by micro‐complement fixation) from S100‐protein present in human brain.
Screening for neurotransmitters: A rapid radiochemical procedure
Authors: Hildebrand John G. , Barker David L. , Herbert Edward , Kravitz Edward A. 
Published: January 2005

AbstractAmong the known or suspected neurotransmitter compounds are: acetylcholine, norepinephrine, γ‐aminobutyric acid, epinephrine, 5‐hydroxytryptamine, dopamine, and octopamine. This communication describes a rapid screening procedure for identifying which of these substances are likely candidates for neurotransmitters in a particular tissue. The method is based on the selective synthesis and localization of transmitters in those cells which are presumed to release them. The procedural steps are: (1) incubation of tissue in a physiological medium containing one or more radiochemical precursors of suspected transmitters; (2) acidic extraction of all or selected parts (e.g., single cells) of the incubated tissue; (3) high‐voltage paper electrophoresis of the extract under conditions which separate most of the compounds of interest; and (4) quantification of isotope in each transmitter candidate. The effectiveness and sensitivity of the method have been shown with several preparations whose transmitters are known. In certain cases the sensitivity can extend to a single cell level. Preliminary results are also reported on the application of the technique to a lobster sensory system of unknown transmitter chemistry, the abdominal muscle receptor organ.
Influence of lanthanum on transmitter release at the neuromuscular junction
Authors: DeBassio William A. , Schnitzler Ronald M. , Parsons Rodney L. 
Published: January 2005

AbstractThe presynaptic influence of lanthanum on neuromuscular transmission was studied in the isolated sciatic nerve‐sartorius muscle preparation of the frog, Rana pipiens. Twitch tension output from indirectly stimulated muscles progressively decreased with increasing concentrations of La3+ from 0.01 to 1.0 mM and was abolished in the presence of 0.5 mM and 1 mM La3+ after approximately 50 min and 15 min, respectively. Studies on directly stimulated muscle indicated that the inhibition by La3+ of tension development during indirect stimulation was not primarily of myogenic origin. The decrease in indirectly stimulated twitch tension by 0.5 mM La3+ was reduced by pretreatment in 10 mM Ca2+, but was not overcome by 1 mM TEA or 5 mM guanidine. In contrast, blockade produced by 8.2 mM Mg2+ was alleviated by TEA or guanidine. In Mg2+ poisoned preparations, microperfusion of 0.001 mM La3+ decreased m by 70% (5 fibers). In curarized preparations, the presence of 0.001 mM La3+ caused the EPP to decrease by 57% (3 fibers), and 0.5 mM Mg2+ decreased the EPP by 61% (4 fibers). Although the EPP amplitude was reduced by La3+, the MEPP frequency was markedly potentiated in the presence of 0.001 to 0.5 mM La3+. The potentiation of MEPP frequency by La3+ appeared to be enhanced in the absence of calcium and reduced by pretreatment in a 10 mM Ca2+ Ringer solution. It is suggested that La3+ blocks transmission presynaptically by decreasing the quantal content of the EPP, and that it is a more efficient blocker of evoked release than Mg2+.
Effects of environmental enrichment and impoverishment on rat cerebral cortex
Authors: Diamond Marian C. , Rosenzweig Mark R. , Bennett Edward L. , Lindner Bernice , Lyon Lennis 
Published: January 2005

AbstractThe first part of this paper deals with rat brain anatomy as affected by variations of starting age and of duration of exposure to enriched (complex) or impoverished (restricted) environmental conditions. Cerebral cortical depth measurements and weights of brain samples are compared. The second part of this report is concerned with an attempt to establish the extent to which the enriched condition or the improverished condition is responsible for the histological brain changes; this is done by comparison with brains from animals in the standard colony environment. The results indicate that both larger and more extensive cortical depth effects are found in rats exposed for 30 days rather than 80 days to their respective environments. The effects of enrichment are more prominent in the dorsal cortical segments, whereas the effects of impoverishment are more evident in the lateral cortical segments. More precise localization of cortical changes is obtained by measuring the depths at many segments than by taking the weights of relatively large blocks of tissue.
Transependymal transport of thiocyanate
Authors: Pollay M. , Kaplan R. 
Published: January 2005

AbstractThe transependymal movement of thiocyanate (SCN−) was measured in the isolated choroid plexus of the sheep. The movement of SCN− from CSF to choroidal venous blood was separated into a nonlinear (saturable) and linear (nonsaturable) component. It was believed that the former component represented the active transport of SCN− from CSF to blood across the choroidal ependyma since it occurred against a concentration gradient and was adversely affected by the presence of a competing anion (iodide) and derangement of cellular respiration. These findings strongly support the role of choroid plexus in rapidly clearing the intraventricular of CSF of SCN− by an active transport process.
The neuronal basis of behavior in Tritonia. III. Neuronal mechanism of a fixed action pattern
Authors: Willows A. O. D. , Dorsett D. A. , Hoyle G. 
Published: January 2005

AbstractWe have investigated the roles played by numerous identified brain cells in initiating and controlling the coordinated sequence of movements of an instinctive escape‐swimming sequence in an intact animal preparation of the nudibranch mollusc Tritonia diomedia. Intracellular electrical activity in different neurons has been correlated with the various phases of the behavior. We recognized four major stages in the response: (1) reflex local withdrawal; (2) preparation for swimming; (3) swimming; and (4) termination. We have located and studied brain cells whose activity is associated with the following aspects of swimming: withdrawal; elongation; triggering behavior; dorsal flexion; ventral flexion; and neurons which excite both dorsal and ventral flexor neurons simulataneously.We find that specific neurons play clearly defined and invariant roles in control of escape‐swimming and that the neuronal circuitry underlying the coordination of the sequence is the same in different individuals of the species. Details of the neuronal circuitry and a number of the general functional attributes of interacting cell groups have been determined directly or inferred from observations of cell to cell interactions. A preliminary model of the neuronal apparatus which controls this behavior is discussed. The principal findings are: (1) a discrete group of electrically coupled neurons determines, by its output, whether or not escapeswimming will be executed; (2) the neuronal elements responsible for execution of the swimming stages of the sequence are maintained in an excited state for the required period, in part by a regenerative feedback system; (3) alternating bursts of impulses in functional antagonists are co‐ordinated in part by reciprocal inhibition between them; and (4) termination of the sequence occurs abruptly at a particular phase in the swimming cycle and appears to be an active neural process, rather than a simple running‐down.
Multiple forms of acetylcholinesterase and their distribution in endplate and non‐endplate regions of rat diaphragm muscle
Authors: Hall Zach W. 
Published: January 2005

AbstractThe properties of the cholinesterase activity in homogenates of whole rat diaphragm and of innervated (+EP) and non‐innervated (−EP) regions of the muscle have been investigated. Under standard assay conditions, over 90% of the cholinesterase activity of whole muscle homogenates was due to specific acetylcholinesterases. The specific activity of acetylcholinesterase was higher in +EP regions of muscle than in −EP regions. About 40% of the total activity was calculated to be specifically associated with the endplates. When a high speed supernatant fraction of muscles homogenized in 1 M NaCl, 0.5% Triton X‐100 was subjected to velocity sedimentation in a sucrose gradient, and three species of acetylcholinesterase activity with sedimentation constants of 4 S, 10 S and 16 S were observed. All three forms were stable under the conditions of sedimentation and had buoyant densities of approximately 1.28. All three hydrolyzed β‐methylacetylcholine at approximately 30% the rate that acetylcholine was hydrolyzed. The 10 S and 16 S forms were inhibited by concentrations of acetylcholine over 1.25 mM, but no substrate inhibition was observed with the 4 S enzyme. Velocity sedimentation of extracts from +EP and −EP regions of muscle demonstrated that the 4 S and 10 S forms of the enzyme were distributed throughout the muscle while the 16 S form was found only in +EP regions. Extracts of the phrenic nerve contained only 4 S and 10 S forms. Thus, the 16 S form of acetylcholinesterase is specifically associated with endplate regions of muscle and may correspond to the endplate enzyme. Seven days after denervation of the diaphragm, both endplate‐specific cholinesterase activity and the cholinesterase activity in −EP regions of muscle were decreased. Although the activity of all three forms of acetylcholinesterase were decreased in denervated muscle, the largest proportional decrease occurred in the activity of the 16 S form.
Oculomotor areas in the rabbit's midbrain and pretectum
Authors: Collewijn H. 
Published: January 2005

AbstractThe role of some meso‐ and diencephalic structures in eye movements was investigated by ablation and stimulation experiments. Optokinetic nystagmus was abolished by small lesions in the lateral pretectum, but not by complete removal of the superior colliculi. Stimulation of the superior colliculus and other visual centers was effective in eliciting nystagmus (slow phase ipsilateral), but the most efficient trigger zones are found in the lateral pretectum and the midbrain tegmentum. Only from these areas could nystagmus still be elicited after degeneration of the primary optic fibers. The lateral pretectal trigger zone is probably identical with the nucleus of the optic tract. It is postulated that this nucleus is an essential station for horizontal optokinetic reactions. Saccades were obtained by stimulation of the mesencephalic central grey, but not for any visual centers such as the superior colliculus.
Isolation and polymerization of brain actin
Authors: Moring Stephen , Ruscha Mary , Cooke Peter , Samson Fred 
Published: January 2005

AbstractThe studies presented here confirm earlier reports that an actin‐like protein is abundant in brain. However, when the traditional procedures for isolating muscle actin are applied to brain, many different proteins are extracted. Tubulin, a major protein in brain with properties similar to actin, is the major constituent. A method is described for isolating the “brain actin” to a purity of 90–95%. The isolation method begins with an extraction of bovine brain in low ionic strength buffer with ATP and sucrose. The extract is treated with NH4SO4, MgCl, and KCl and incubated at 37°C. A precipitate is formed which contains primarily tubulin and brain actin. Resolubilization of the brain actin is achieved with a low ionic strength buffer solution with sucrose and ATP. Further purification is accomplished by a cycle of polymerization—depolymerization. This “brain actin” shares with muscle actin the following properties: (1) Similar molecular weight and molecular charge as determined by SDS polyacrylamide gel and ordinary disc electrophoresis; (2) Polymerization to a filamentous form under the same conditions; (3) Contains 3‐methylhistidine; (4) Vinblastine sulfate will induce filament formation.
Development of spinal cord bioelectric activity in spinal chick embryos and its behavioral implications
Authors: Provine Robert R. , Rogers Lynn 
Published: January 2005

AbstractEmbryonic behavior of the chick is the product of spontaneous multiunit burst discharges within the ventral spinal cord. The present study describes the ontogeny of spinal cord burst discharges in embryos which were deprived of brain input by removing several neural tube segments of 2‐day embryos at cervical or mid‐thoracic levels. Characteristics of bioelectric activity present in both intact and chronically transected cords are: (a) the appearance of spike discharges; (b) the organization of unit discharges into synchronized multiunit bursts; (c) the establishment of intracord synchronization of burst discharges over wide expanses of cord tissue; (d) an increase in burst duration and complexity at 7 days due to the appearance of the burst afterdischarge; (e) an increase in the amount of burst activity from 6 to 13 days followed by a decline until hatching at 21 days; (f) a shift from periodic to irregular patterns of burst activity at 13 days; and (g) the existence of the cord burst discharge as a correlate of embryonic movement.Several differences were found between burst activity from chronic spinal and intact embryos: (a) cervical spinal embryos were significantly less active than controls from 15 through 19 days; and (b) long sequences of unusual repetitive burst afterdischarges appeared in chronic spinal embryos by 13 days.The results indicate that the transected embryonic spinal cord is remarkably autogenous in function, although patterns of activity unique to the transected cord appear and increase in prominence during later stages of incubation.
Impaired axonal regeneration in acrylamide intoxication
Authors: Griffin John W. , Price Donald L. , Drachman Daniel B. 
Published: January 2005

AbstractAcrylamide is a neurotoxin known to impair regeneration of axons following nerve crush and to produce structurally abnormal regenerating sprouts. To investigate the mechanism of these abnormalities, protein synthesis and fast axonal transport were studied in acrylamide‐intoxicated and control rats 2 weeks after sciatic nerve crush. Using an in vitro preparation of sciatic nerve‐dorsal root ganglion, there was no difference in ganglion 3H‐leucine incorporation between the two groups. In these preparations of sensory axons, as well as in motor axons studied in vivo, a smaller proportion of rapidly transported radioactivity was carried beyond the crush in the acrylamide‐regenerating nerves compared to the control‐regenerating nerves. Correlative ultrastructural studies demonstrated that this difference reflected the impaired outgrowth of the acrylamide‐regenerating nerves, rather than an abnormality in fast transport. The acrylamide‐treated sprouts often developed swellings filled with whorls of neurofilaments; in addition, many sprouts ended in massively enlarged growth cones containing membranous organelles. EM autoradiography showed labeled, rapidly transported organelles accumulated in the neurofilamentous whorls, and therefore suggested that these organelles might be “trapped” or impeded in passage through these regions. However, there was no evidence that the growth cones received insufficient amounts of transported protein; in fact, the distended endings were densely labeled and apparently “ballooned” by transported organelles.These results suggest that acrylamide intoxication does not impair regeneration by diminishing the delivery of rapidly transported materials to the growing tip. Rather, the marked distention of the growth cones is interpreted as the morphological consequence of continued delivery of rapidly transported organelles into sprouts unable to utilize them in outgrowth.
Structure and function of spiny lobster ligamental nerve plexuses: Evidence for synthesis, storage, and secretion of biogenic amines
Authors: Sullivan Robert E. , Friend Brenda J. , Barker David L. 
Published: January 2005

AbstractThree pairs of ligaments support not only the heart of spiny lobsters but also ligamental nerve plexuses, the complex terminal aborizations of segmental nerves. Segmental nerves 1–4 project from the thoracic ganglia into the pericardial cavity and ultimately ramify along the strands of the anterior, medial, and posterior ligaments. In each branch, a core of large axons sends fibers to terminate in a surrounding cortex of fine and varicose secretory processes. Electron micrographs reveal at least five distinct populations of granule‐filled neuronal profiles, many with vesicles clustered at membrane thickenings adjacent to the epineural sheath.The ligamental nerve plexuses synthesize and accumulate octopamine, dopamine, 5‐HT, and acetylcholine. Octopamine and 5‐HT are predominant, comprising 33% and 65%, respectively, of the synthetic activity devoted to the four amines. Thus, the anatomy, ultrastructure, and neurochemistry of the ligamental nerve plexuses establishes their homology with the pericardial organs of other Crustacea.Octopamine and 5‐HT are released by a Ca++‐dependent mechanism upon electrical stimulation of preterminal nerve trunks, and, in vivo, would be swept immediately through ostia into the heart. These observations, when considered with known effects of octopamine and 5‐HT on crustacean cardiac activity, neuromuscular transmission, muscle tension, and cyclic AMP metabolism provide a strong case for hormonal actions at target sites throughout the animal.Segmental nerve processes in the dorsal nerve trunk ramify into a plexus around the dorsal nerve apparatus, a small muscular bulb that lies recessed in the cardiac surface. The dorsal nerve, carrying excitatory and inhibitory input to the cardiac ganglion directly through the bulb's hollow interior. The apparatus synthesizes and contains acetylcholine and the three amines mentioned above. In situ, it may beat rhythmically out of phase with the heart.