bluuebunny/crossref_metadata_2025 huggingface dataset:
Childhood‐onset oculopharyngodistal myopathy with chronic intestinal pseudo‐obstruction
Authors: Amato Anthony A. , Jackson Carlayne E. , Ridings Larry W. , Barohn Richard J.
Published: January 2005

Oculopharyngodistal myopathy is characterized by the adult onset of ptosis, external ophthalmoplegia, dysphagia, and distal weakness. Although dysphagia is common, other gastrointestinal involvement has not been described. We report a case with childhood onset who developed chronic intestinal pseudo‐obstruction. Other myopathies associated with ophthalmoplegia and intestinal pseudo‐obstruction such as mitochondrial cytopathies were excluded. Whether oculopharyngodistal myopathy is a variant of oculopharyngeal muscular dystrophy or a distinct neuromusclar disorder is unknown and requires further study. © 1995 John Wiley & Sons, Inc.
Ca2+ Release channels of pigs heterozygous for malignant hyperthermia
Authors: Shomer Nirah H. , Mickelson James R. , Louis Charles F.
Published: January 2005

Porcine malignant hyperthermia (MH) is an autosomal recessive disorder resulting from a mutation in the skeletal muscle sarcoplasmic reticulum (SR) Ca2+ release channel. The Ca2+ release properties of SR vesicles isolated from pigs heterozygous for the MH gene have been demonstrated previously to be intermediate to those of vesicles isolated from MH‐susceptible (MHS) and normal pigs. The Ca2+ release channel is tetrameric, so the intermediate Ca2+ release properties of heterozygous pig SR preparations could result either from populations of MHS and normal homotetramers, or populations of heterotetrameric Ca2+ release channels with properties unique from those of the two types of homozygous channels. To discriminate between these possibilities, the single channel percent open time (Po) and channel dwell time distributions of SR Ca2+ release channels were analyzed. These data suggest that the heterozygous porcine Ca2+ release channel population must contain heterotetramers with properties distinct from those of either MHS or normal channels. The data also imply that the Ca2+ release channel population in MHS humans who are heterozygous for a dominant mutation in this protein also contains heterotetrameric channels.© 1995 John Wiley & Sons, Inc.
Immunolocalization of triadin, DHP receptors, and ryanodine receptors in adult and developing skeletal muscle of rats
Authors: Carl S. Lewis , Felix K. , Caswell A. H. , Brandt N. R. , Brunschwig J.‐P. , Meissner G. , Ferguson D. G.
Published: January 2005

The dihydropyridine receptors (DHPR) and the ryanodine receptors (RyR) are well‐characterized proteins of the triad junctions of skeletal muscle fibers. Recently, a newly discovered 95‐kDa protein, triadin, has been purified from rabbit skeletal muscle heavy sarcoplasmic reticulum (SR) vesicles. WE have used indirect immunogold EM to localize triadin to the junctional face of the SR in isolated triads. In addition, we have used indirect immunofluorescence to localize triadin in relation to the DHPR and the RyR in adult and developing rat skeletal muscle. In double immunolabeling experiments of longitudinally oriented adult rat skeletal muscle tissue, triadin‐specific and RyR‐specific antibodies resulted in a characteristic striated staining pattern. The staining arising from these antibodies completely overlapped when examined by computer analysis of digitized laser scanning confocal microscopy images. A similar result was obtained in double staining experiments using antibodies raised against the DHPR and the RyR suggesting that all three proteins are located in the triads in situ. The developmental expression of the three triad proteins was examined using double labeling of skeletal muscle tissue from several fetal and early postnatal ages. The staining patterns of triadin, RyR, and DHPR antibodies were overlapping throughout development, suggesting that from their earliest appearance the three proteins are components of the triads. © John Wiley & Sons, Inc.
Immunocytochemical localization of vinculin in muscle and nerve
Authors: Massa Roberto , Silvestri Giulia , Sancesario Giuseppe , Bernardi Giorgio
Published: January 2005

A complete survey of the immunofluorescence distribution of the cytoskeletal protein vinculin in the normal skeletal muscle and peripheral nerve of humans and of different rodent species was performed. Our results enable us to localize vinculin in different types of adhesion plaques such as sarcolemmal costameres and neuromuscular and myotendinous junctions, but also in a fine intermyofibrillar lattice, possibly associated with intermediate filaments and/or with the triads. Moreover, we describe the presence of vinculin in junctional domains of several, previously unrecognized, specialized cells such as: the outer sheath of the muscle spindle capsule, the multilayered flat cells of the perineurium, the smooth muscle cells of epineurial blood vessels, and the endothelial cells in the endoneurium. These data call for a major role of vinculin in mechanisms of adhesion between cells, between cell and substrate and between intermyofibrillar components in the neuromuscular system. Such knowledge provides an anatomical background for studies on the possible pathological effects induced by an impairment in vinculin function. © John Wiley & Sons, Inc.
Desmin‐related neuromuscular disorders
Authors: Goebel Hans H.
Published: January 2005

Desmin, the intermediate filament protein of skeletal muscle fibers, cardiac myocytes, and certain smooth muscle cells, is a member of the cytoskeleton linking Z‐bands with the plasmalemma and the nucleus. The pathology of desmin in human neuromuscular disorders is always marked by increased amounts, diffusely or focally. Desmin is highly expressed in immature muscle fibers, both during fetal life and regeneration as well as in certain congenital myopathies, together with vimentin. Desmin is also enriched in neonatal myotonic dystrophy and small fibers in infantile spinal muscular atrophy. Focal accretion of desmin may be twofold, in conjunction with certain inclusion bodies, cytoplasmic and spheroid bodies, and in a more patchy fashion, granulofilamentous material. Both lesions have been found in certain families, affected by a myopathy and/or cardiomyopathy. Other proteins, e.g., dystrophin, vimentin, actin, ubiquitin, and α‐B crystallin, may also be overexpressed. Desmin pathology may be genetically regulated or may merely reflect profoundly impaired metabolism of several proteins within myofibers. © John Wiley & Sons, Inc.
Electrophysiological and urodynamic studies to monitor surgical outcome in children with tethered spinal cords
Authors: Kothari Milind J. , Bauer Stuart B. , Logigian Eric L. , Shefner Jeremy M.
Published: January 2005

Children with myelodysplasia often develop tethering of their spinal cord within 2–3 years after correction of their initial birth defect, leading to either neurological or urological dysfunction. Surveillance of these children includes electrophysiologic/urodynamic (EMG/UDS) studies to monitor improvement or deterioration of their neurourological function. We reviewed 39 patients who underwent surgical untethering from 1979 to 1994 to determine whether postoperative EMG/UDS studies were useful in assessing outcome after surgery. All patients had a complete neurologic examination and an EMG/UDS prior to and 3 months after surgery. Twenty patients (51%) showed improvement in their EMG/UDS study after untethering, 15 (39%) demonstrated no significant change, and 4 (10%) showed deterioration. Improvement consisted of either return of previously absent motor units, return of sacral reflexes, or improved bladder dynamics. In a further 3 patients, subsequent deterioration on serial postoperative EMG/UDS testing was the first indication of recurrent tethering. We conclude that serial EMG/UDS evaluation in patients at risk for tethering of the spinal cord may serve as a useful adjunct to close clinical observation. © 1995 John Wiley & Sons, Inc.
Vrms/T quantitation: usefulness in patients with neuropathies
Authors: Fisher Morris A. , Itkin Arthur
Published: January 2005

This 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

Because 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

Manganese 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

It 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

A 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

Among 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

The 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

The 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

The 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

We 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

The 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

The 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

The 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

Embryonic 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

Acrylamide 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

Three 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.
Bidirectional axonal transport of free glycine in identified neurons R3–R14 of Aplysia
Authors: Price Christopher H. , McAdoo David J. , Farr William , Okuda Roy
Published: January 2005

The axonal transport of 3H‐amino acids was studied in the axons of identified neurons R3–R14 in the parietovisceral ganglion (PVG) of the mollusc Aplysia. The PVG was incubated (3–24 hr) in media containing physiological concentrations of single 3H‐amino acids while the isolated nerve was superfused with plain or chemically altered media. The nerve was then sliced into sequential segments for biochemical analyses or fixed for autoradiography. 3H‐glycine was transported at 70 mm/day in 6X greater quantities than other amino acids which were transported at <40 mm/day. In the 3H‐glycine experiments, >80% of the label transported into the nerve remained as free glycine, comigrating with glycine in thin‐layer chromatographs. In autoradiographs of sections 4 mm from the ganglion‐nerve barrier, >50% of the silver grains were over R3–R14 axons which occupy <10% of the nerve cross‐sectional area. EM autoradiographs confirmed that grains were within R3–R14 and not in surrounding glia. The selective transport of glycine was inhibited by Hg2+, by vinblastine and Nocodazole, and by low Ca2+ media. Autoradiographs of vinblastine‐treated nerves showed a drastic reduction in label over R3–R14 and other axons. Label was also transported retrogradely; this transport rate was similar to the orthograde rate, but 5–10 times less label moved retrogradely. Autoradiographs showed that the retrograde label was localized to R3–R14 axons. This report clearly demonstrates the rapid, selective, and bidirectional transport of a free amino acid and provides further evidence that glycine may be used as a neurochemical messenger by neurons R3–R14.
Investigation of burst generation by the electrically coupled cyberchron network in the snail Helisoma using a single‐electrode voltage clamp
Authors: Merickel Michael , Gray Richard
Published: January 2005

This paper describes the results of investigating burst generation by the cyberchron network in the snail Helisoma. The cyberchron network is composed of approximately 20 electrically coupled neurons and controls the feeding behavior of the snail. The electrical coupling between network members has made it particularly difficult to distinguish between the importance and involvement of single‐cell and network properties in burst generation by this system. The present investigations utilized the new single‐electrode voltage clamp to examine the membrane properties and network interactions of the cyberchron neurons: (1) A slow outward current is activated by moderately large depolarizing commands (−40 to 0 mV) and does not undergo inactivation decay (i.e., decline in magnitude) during a command potential step maintained for 10 sec or more. The lack of inactivation of the outward current in cyberchron neurons appears to be due to the dominating role of a Ca‐dependent K current. (2) There are two functionally distinct classes of cyberchrons—current generator cyberchrons and follower cyberchrons. (3) Primary current generator cyberchrons have membrane properties similar to endogenous bursting neurons (e.g., persistent inward Ca current and negative resistance region in I–V plot) and appear to provide the main driving and timing current for the rest of the network. (4) The vast majority of cyberchrons are secondary current generator cyberchrons with membrane properties which exhibit inward‐going rectification and appear to burst as a result of regenerative excitation with one another and the primary current generator cyberchrons. (5) The second class of cyberchrons are driven by the electrical synaptic input from the current generator cyberchrons, do not exhibit inward‐going rectification, and are called follower cyberchrons. (6) Burst termination is due to activation of a slow outward tail current in most cyberchrons during the burst (probably Ca‐activated K current) which causes a hyperpolarization in individual cyberchrons, terminating the burst. (7) Decay of the outward tail current causes the cyberchrons to depolarize, which activates the persistent inward Ca current in the primary current generator cyberchrons, starting the burst cycle anew.
Muscarinic cholinergic binding sites in an orthopteran central nervous system
Authors: Meyer Mark R. , Edwards John S.
Published: January 2005

Homogenates of cricket (Acheta domesticus) central nervous system (CNS) specifically bind the potent muscarinic ligand [3H]‐QNB. Binding assay and pharmacologic data indicate that the cricket CNS contains a high density of muscarinic cholinergic binding sites. These sites appear to be a unique class of invertebrate cholinergic receptor with properties distinct from those of previously described nicotinic receptors.
The peripheral and central nervous organization of the locust coxo–trochanteral joint
Authors: Bräunig Peter
Published: January 2005

The micromorphology of the locust coxo–trochanteral joint was examined in cobalt‐stained material. Peripheral nervous system, musculature, and internal proprioceptors—two strand receptors and a muscle receptor organ—of the metathoracic coxa are compared with those of the pro‐ and mesothoracic legs. The number and position of trochanter levator and depressor motoneurons as well as the central projections of coxal sense organs are described. Evidence for a femoro–tibial strand receptor was obtained by tracing the path of a particular nerve branch.
A comparative study by serial electron microscopy of neuromuscular junctions in the dimorphic claws of the snapping shrimp, Alpheus heterochelis
Authors: Phillips Christine E. , Wilson John A. , Mellon Deforest
Published: January 2005

We compared the neuromuscular junctions on the main closer muscle in the first pair of chelipeds in the snapping shrimp Alpheus heterochelis by serial section electron microscopy. We sought an ultrastructural basis for the different behavioral and physiological functions of these dimorphic claws and for the role of the nervous system in claw transformation. We were unable to detect any statistically significant morphological differences between the junctions. Further, we found the muscle fiber populations and filament arrangements, as well as the electrical properties of the fibers, to be more homogeneous and similar to each other in A. heterochelis than those reported for another species, A. armillatus. We consider our results in light of recent data on the anatomy and electrical properties of the motor neurons within the CNS and conclude that the neural trigger for claw transformation involves factors not revealed by conventional electron microscopy.
Calcium‐activated potassium conductance noise in snail neurons
Authors: Westerfield Monte , Lux H. D.
Published: January 2005

Current fluctuations were measured in small, 3–6‐μm‐diameter patches of soma membrane in bursting neurons of the snail, Helix pomatia. The fluctuations dramatically increased in magnitude with depolarization of the membrane potential under voltage clamp conditions. Two components of conductance noise were identified in the power spectra calculated from the membrane currents. One component had a corner frequency which increased with depolarization. This component was blocked by intracellular injection of TEA and was relatively insensitive to extracellular calcium levels (as long as the total number of effective divalent cations remained constant). It was identified as fluctuations of the voltage‐dependent component of delayed outward current. The second component of conductance noise had a corner frequency which decreased with depolarization. It was relatively unaffected by TEA injection and was reversibly blocked by substitution of extracellular calcium with magnesium, cobalt, or nickel. This second component of noise was identified as fluctuations of the calcium‐dependent potassium current. The results suggest that the two components of delayed outward current are conducted through physically distinct channels.
Rapid axoplasmic transport of free leucine
Authors: Schmid Georg , Wagner Lothar , Weiss Dieter G.
Published: January 2005

Axoplasmic transport of free 3H‐leucine has been studied in vivo in the pike olfactory nerve following application of labeled leucine to the olfactory mucosa. A considerable amount of free 3H‐leucine is transported at constant velocity along the axon in the form of a distinct peak. The maximum transport velocity for free 3H‐leucine is the same as for rapidly transported 3H‐protein (130 and 135 mm/day, respectively, at 19°C). Microtubule inhibitors block or significantly reduce the amount of free 3H‐leucine transported, but do not influence the transport velocity. Disruption of the oxygen supply abolishes free 3H‐leucine transport, so that this phenomenon cannot be explained by diffusion. The amount of free leucine in the rapidly moving peak decreases with time and distance along the axon and is not detectable after 5 h or more. The transported 3H‐leucine is not derived from the circulation or from proteolysis of rapidly transported proteins. This study may help to resolve the controversy over the axoplasmic transport of free amino acids since it shows that free 3H‐leucine is transported rapidly but does not travel by rapid axoplasmic transport to the end of axons longer than about 30 mm.
Electrophoretic analysis of axonally transported proteins in rabbit vagus nerve
Authors: McLean W. G. , McKay A. L. , Sjøstrand J.
Published: January 2005

Proteins synthesized in the nodose ganglia of rabbits were radiolabeled with 35S‐methionine and the proteins present in the vagus nerve, at various times later, were analyzed by SDS (sodium dodecyl sulfate)–polyacrylamide gel electrophoresis. Three major groups of proteins were transported as waves of radioactivity within the nerve at rates of 15–17 mm/h, 12–15 mm/day, and 25–30 mm/day. The front of the fastest wave was composed of two proteins only, of apparent molecular weights 21,000 and 24,000. These were followed after a delay by a number of proteins of higher molecular weight, traveling at the same fast rate. The 25‐mm/day wave contained several proteins including a major one of molecular weight 43,000 while the 12‐mm/day wave was composed entirely of two proteins of molecular weights 54,000 and 56,000. These groups of slowly transported proteins are therefore similar to those transported much more slowly in other mammalian nerves, with the exception that no proteins with molecular weight similar to the neurofilament proteins could be detected. We have confirmed the dependence of slow transport for both groups of proteins on contact between cell body and axon and suggest that it may be a general phenomenon in all mammalian nerves.
Dopamine in a molluscan nervous system: Synthesis and fluorescence histochemistry
Authors: Trimble Dorothea L. , Barker David L. , Bullard Brad J.
Published: January 2005

The nervous system of the pond snail, Helisoma trivolvis, was investigated for its ability to synthesize and accumulate 3H‐catecholamines from 3H‐tyrosine. 3H‐Dopamine, but not 3H‐norepinephrine, was synthesized by several ganglia. The highest accumulations were found in the cerebral, pedal, and buccal ganglia. The Falck‐Hillarp and glyoxylic acid fluorescence histochemical techniques were applied to the buccal ganglia to visualize dopamine‐containing cells. Fluorescing cells were found on both dorsal and ventral sides of the ganglion. Peripheral nerves of the buccal ganglia also displayed catecholamine fluorescence and accumulated 3H‐dopamine. However, no 3H‐dopamine synthesis occurred in the cerebral‐buccal connectives, which connect the buccal ganglia with the rest of the central nervous system. Therefore, we conclude that there is a dopaminergic system intrinsic to the buccal ganglia and their peripheral targets.
One‐trial reward learning in the snail Lymnea stagnalis
Authors: Alexander James , Audesirk Teresa E. , Audesirk Gerald J.
Published: January 2005

We present evidence that the pond snail Lymnaea stagnalis is capable of aquisition and extensive retention of an appetitively reinforced feeding response after only a single training trial. Food‐deprived snails presented with a single pairing of a phagostimulant (a mixture of sucrose and casein digest) and a novel, non‐food chemostimulus (amyl acetate) subsequently made feeding responses to the amyl acetate and retained the association for at least 19 days. This demonstration of one‐trial, non‐aversive classical conditioning enhances the utility of Lymnaea stagnalis as a model system for the detailed analysis of neural mechanisms underlying plasticity.
Extracellular calcium dependence of contracture and modulation by serotonin in buccal muscle E1 of Aplysia
Authors: Ram Jeffrey L. , Shukla Umesh A. , Parti Rajesh , Goines Roy L.
Published: January 2005

Serotonin [5‐hydroxytryptamine (5‐HT)] enhances acetyl choline (ACh)‐elicited contractures of Aplysia buccal muscles E1 and I5. The possible role of external calcium in regulating the magnitude of ACh contracture in the presence and absence of 5‐HT was investigated. Superfusion of E1 with zero calcium medium caused ACh contractures to fail within one to two minutes. Recovery of ACh contracture upon restoring normal medium occurred within two to four minutes. In the absence of 5‐HT, ACh contracture decreased proportionally to external [Ca++] in the concentration range of 0–10 mM; however, the amount of enhancement of of ACh contracture following 5‐HT treatment did not decrease with external [Ca++] as long as [Ca++] was above a threshold concentration that varied from preparation to preparation. For most preparations, the enhancement of ACh contracture by 5‐HT was dependent on the presence of external calcium during 5‐HT treatment. Calcium influx into muscles E1 and I5 increased approximately two and a half fold in the presence of 10−6 M 5‐HT. A model in which 5‐HT brings about calcium “loading” of an ACh releasable intracellular storage site is discussed.
Inhibition of the retrograde axonal transport of acetylcholinesterase by the anti‐calmodulin agents amitriptyline and desipramine
Authors: Tiberi M. , Lavoie P.‐A.
Published: January 2005

The possible involvement of calmodulin in mediating the calcium requirement for retrograde axonal transport of acetylcholinesterase was studied in vitro in bullfrog spinal nerves, with the use of the calmodulin inhibitors amitriptyline and desipramine. When nerves were preincubated with 0.2 mM amitriptyline or desipramine for 5 h, and were then ligated and incubated for an additional 17–18 h in drug‐containing medium, the accumulation of acetylcholinesterase distal to the ligature was significantly reduced as compared to contralateral control nerves maintained in drug‐free medium. The identical degree of transport inhibition observed for both drugs is consistent with their similar anti‐calmodulin activity.
Restoration of sensory and motor function in earthworm escape reflex pathways following ventral nerve cord transplantation
Authors: Vining E. P. , Drewes C. D.
Published: January 2005

Twelve segments of earthworm ventral nerve cord (VNC) were excised from either segments 10–22 (i.e., within the MGF sensory field) or segments 75–87 (i.e., within the LGF sensory field) in donor worms and heterotopically, or homotopically, transplanted into recipient animals. Morphological evidence indicated that by four days after transplantation, peripheral connections were formed between the transplanted VNC and the body wall of the recipient, many of these connections involving novel pathways projecting ventrally from the transplant. Restoration of giant fiber touch sensitivity in the transplant occurred from 4–14 days after transplantation. Regardless of the site of transplantation, the restored sensitivity (i.e., MGF versus LGF sensory field) always reflected the origin of the donor VNC. Restoration of MGF‐mediated motor activity in the transplant occurred approximately 17–22 days after transplantation. In the case of heterotopic transplants (i.e., anterior VNC into posterior segments), the restored MGF‐mediated muscle potentials were facilitating, indicating at least some tendency for persistance of this feature after transplantation. Behavioral observations suggested that reconnections involving other reflex pathways (e.g., those controlling setal movements and peristaltic locomotion) were made within the transplant region and that properties of the restored reflexes reflected those of the donor VNC. The rapid restoration of sensory and motor connections, despite heterotopic placement, indicates a significant capacity for peripheral regeneration by the transplanted VNC. On the other hand, the maintenance of various properties of reflex function, despite heterotopic transplantation, suggests a limited capacity for rearrangement of established central connections in the transplanted VNC.