bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sonication‐enhanced histochemistry of wheat germ agglutinin binding to intracellular sites of rat layer V cortical neurons and spinal motoneurons
Authors: Wells Michael R. , Bernstein Jerald J. 
Published: January 2005

AbstractCellular surface carbohydrates have been studied extensively in relation to cell interactions. However, the presence of intracellular carbohydrates not associated with cell surface membranes has not been well‐defined histochemically. We describe a technique for the ultrastructural localization of intracytoplasmic carbohydrates using a wheat germ agglutinin peroxidase conjugate.The ultrastructural aspects of wheat germ agglutinin (WGA) binding to intracellular structures of rat somatomotor cortex layer V neurons and spinal cord motoneurons were examined using sonication to enhance penetration of the lectin–peroxidase conjugate. In addition to the membrane‐associated structures previously described by others, WGA binding was observed on neuronal nuclear chromatin, nuclear pores, ribosomes, microtubules, vesicular organelles, and to synaptic complexes, primarily in the presynaptic bouton. The results support data indicating that complex carbohydrates may be important in neuronal molecular processing.
Prenatal development of the human spinal cord. I. Ventral motor neurons
Authors: Rath G. , Gopinath G. , Bijlani V. 
Published: January 2005

AbstractDifferentiation of the ventral motor neurons were followed in the developing human spinal cord from week 8 to week 26 of intrauterine life by thionin staining and the rapid Golgi method. Ventral roots were seen as translucent rootlets by week 8 and the ventral motor neurons were clearly identifiable by week 10, indicating that the ventral grey was earlier to differentiate than the dorsal grey, which showed a small, darkly stained, undifferentiated cell population. Lateral groupings of the motor neurons in the cervical and lumbar enlargements were obvious by week 10. Nissl substance and dendrites had reached an adult pattern by about week 18 of intrauterine life.
Kinetic evidence for decreased methionine adenosyltransferase activity in erythrocytes from schizophrenics
Authors: Kelsoe John R. , Tolbert Lelland C. , Crews Eugene L. , Smythies John R. 
Published: January 2005

AbstractWe have observed significantly lower kinetic parameters (KM and Vmax) for methionine adenosyltransferase activity in erythrocytes obtained from early onset schizophrenics when compared to samples from normal subjects. These differences are apparently not due to differences in S‐adenosylmethionine (SAM) utilization. These results offer an explanation for the conflicting reports of previous investigators and support the concept that undermethylation may characterize some forms of schizophrenia. Methylation is involved in multiple aspects of metabolism and although similar differences in the MAT enzyme in the brain have not been reported, such a deficit could have profound effects on the nervous system. Decreased availability of SAM could decrease catecholamine metabolism or rates of phospholipid methylation.
Serum‐free culture of chicken embryonic sensory ganglia in a balanced salt solution with nerve growth factor for periods up to two weeks
Authors: Rusenko Kirt W. , Stach Robert W. 
Published: January 2005

AbstractCulture of embryonic chicken dorsal root ganglia for periods exceeding a week generally require serum supplementation and a trophic factor such as nerve growth factor. In this communication we describe the culture of chicken E‐9 dorsal root ganglia for period up to 2 weeks in a system that is composed only of a simple basic salts solution and 10 ng/ml (3.8 × 10−10 M) β nerve growth factor. Commercially available tissue culture dishes are used which have a hydrophilic, gas‐diffusable membrane on the bottom to which the ganglia directly attach, eliminating the need for added substratum. Sparse fiber outgrowth appears after 24 hours and growth of the fibers continues for 120 hours of incubation. At this time, the fibers are extremely dense and reach approximately 3.5–4.0 diameters from the body of the ganglion. Continued survival of these fibers appears to depend on the concentration of nonneuronal cells present in the dish. No fiber outgrowth occurs at any time in the absence of β nerve growth factor. The simplicity and purity of this culture system makes it an attractive tool in the study of primary cell‐cell interactions, the production of trophic factors by non‐neuronal cells, and biochemical and physiological analyses of growing neurons.
Target control of neuronal development during formation of the spinal reflex arc: An operant model
Authors: Pollack Emanuel D. , Muhlach William L. 
Published: January 2005

AbstractThe effects of target tissues on the neural centers of the developing spinal reflex arc of frog tadpoles have been integrated to form a model explaining the spatial and temporal interactions of neuron and target. Spinal cord responds to appropriate targets earlier than does sensory ganglion in tissue culture. Neuronal growth and survival responses to target tissues in vitro may explain the regulation of development in situ.
Labeling of poly(A) associated RNA in synaptosomes and the other subcellular fractions of rat cerebral cortex in basal conditions and during training
Authors: Cupello Aroldo , Hyden Holger 
Published: January 2005

AbstractThe labeling of total and poly(A) associated RNA from the subcellular fractions of cerebral cortex was studied after a 1‐hour 3H‐uridine pulse in control and trained rats. In the control animals, the fraction of newly synthesized brain cortex RNA which is found in synaptosomes is the minimal one. However, in synaptosomes the proportion of poly(A)+ RNA within newly synthesized RNA is maximal. Training of the rats does not influence total incorporation of label into RNA in the brain cortex and the distribution of newly synthesized RNA within the subcellular fractions. The proportions of poly(A)+ RNA within total labeled RNA in the various fractions are also unaffected.
Development of bilateral somesthetic inputs into the pericruciate cortex of kittens: Postsynaptic and evoked potentials
Authors: Lenkov Dmitrij N. , Vasilieva Liudmila A. 
Published: January 2005

AbstractThe early postnatal development of somesthetic inputs into the pericruciate cortex of kittens was studied by intra‐ and extracellular recording and cortical surface evoked potential monitoring. Equipotent bilateral influences from the forepaw and hindpaw skin to cortical neurons during the initial postnatal weeks in kittens were revealed. During the fourth week, the functional dominance of contralateral inputs into the motor area becomes evident. Considerable reduction of the latency of postsynaptic and evoked responses only to the contralateral stimulation and the enhancement of their stability and intensity occur.
Loss of Purkinje cell‐associated benzodiazepine receptors spares a high affinity subpopulation: A study with pcd mutant mice
Authors: Vaccarino F. M. , Ghetti B. , Wade S. E. , Rea M. A. , Aprison M. H. 
Published: January 2005

AbstractIn order to identify the relative number of benzodiazepine (BZ) receptors in Purkinje and granule cells, the Purkinje cell degeneration (pcd) mutant mouse was used at, different ages. In these mice, Purkinje cells have degenerated almost completely by 45‐50 days of age. Granule cell loss occurs only later, and is most severe between 180 and 300 days. [3H]Flunitrazepam (FNZ) and [3H]ethyl‐carboline‐3‐carboxylate (β‐CC) were used as ligands. In the 45‐50‐day‐old pcd mice, it was found that there is approximately a 50% decrease in the number of receptors as labeled by [3H]/β‐CC or [3H]FNZ, when the binding is expressed as fmol/cerebellum. The binding decreased by approximately 80%in 300‐day‐old pcd mice (frnol/cerebellum). [3H]FNZ was not displaced by 1 μM R05‐4864, ruling out binding to glial cells. Nonlinear regression analysis of FNZ saturation data provided evidence for two populations of receptors (high and low affinity sites). Only the low‐affinity sites were reduced in number at 45 days. [3H]β‐CC saturation data showed, however, only one population of receptors. The total number of receptors (Bmax) was significantly lower for β‐CC than for FNZ in the control mice. It appears that 50% of the total BZ receptors is associated with Purkinje cells. In addition, our data on 300‐day‐old pcd mutants strongly suggest the existence of granule cell‐associated BZ receptors.
Mouse sciatic nerve regeneration through semipermeable tubes: A quantitative model
Authors: Uzman B. G. , Villegas G. M. 
Published: January 2005

AbstractThe regeneration of transected mouse sciatic nerves using semipermeable acrylic copolymer tubes to enclose both stumps has been qualitatively assessed from 1 to 30 weeks post‐operative. Quantitative morphometric analysis of electron micrograph montages of complete transverse sections of the segment regenerated between stumps has permitted determinations of the percents of total area occupied by the various tissue constituents—blood vessels, epineurium, perineurium, endoneurium, myelinate d axon/Schwann cell units, and unmyelinated axon/Schwann cell units. Significant differences were found in the total cross‐sectional area of segments regenerated through tubes of 1.0 mm versus 0.5 mm internal diameters. Segments regenerated with the distal stump inserted in the tube contained significantly greater percentages of neural units and were significantly larger at 8 weeks post‐operative compared to segments regenerated for 9‐10 weeks with the distal stump avulsed. The morphometric method permits rapid quantitation of sizeable electron micrograph montages which at 1300 × permit all types of tissue components, including the unmyelinated axons, to be visualized.
Distribution of radioactivity among total myelin protein amino acids following administration of labeled glycine, leucine, or methionine
Authors: Wiggins R. C. , Morell P. 
Published: January 2005

AbstractThis paper analyzes the distribution of radioactivity in the different amino acids of brain myelin protein for up to 6‐7 weeks after an intracranial pulse administration of radioactive leucine, glycine, or methionine. Results show that there is no significant accumulation or reutilization of protein radiactivity in any form other than the one administered.
Postnatal development of aminergic projections to frontal cortex: Effects of cortical lesions
Authors: Beaulieu M. , Coyle J. T. 
Published: January 2005

AbstractThe effects of lesions induced by fetal treatment with methylazoxymethanol acetate (MAM) on the developmental synaptic chemistry of the frontal cortex of rats were examined. Treatment at 14 days' gestation (DG) resulted in a 50% decrease in frontal cortical mass whereas treatment at 15 DG caused a 40% decrement. No difference in concentration between MAM and control rats was observed in the postnatal development of the GABA‐ergic markers, glutamate decarboxylase, and GABA. In contrast, the concentrations of the presynaptic markers for the dopaminergic, noradrenergic, and serotonergic terminals were generally elevated in the MAM lesioned frontal cortex throughout postnatal development. The effects of MAM lesion on cholinergic markers were mixed, with minimal alterations in concentration during the first 2 postnatal weeks followed by an increasing disparity thereafter. The results of this study provide additional evidence in support of the differential impact of the cortical hypoplasia on intrinsic neurons as contrasted to aminergic afferents.
Characterization of a subset of oligodendrocytes separated on the basis of selective adherence properties
Authors: Szuchet S. , Yim S. H. 
Published: January 2005

AbstractA subset of oligodendrocytes (B3,f) was isolated by taking advantage of selective cell–substratum interaction. B3,f cells were characterized morphologically, biochemically, and immunocytochemically. Oligodendrocytes were isolated from 4‐to‐6‐month‐old lamb brains by a modified version of our published procedure [Szuchet et al, J Neurosci Methods 3:7–19, 1980]. Freshly isolated cells from band III were plated on plastic culture plates at a concentration of 2 × 106 cells/ml. Approximately 40% of the cells attached to the plate under these conditions. The remaining cells formed small floating clusters. We refer to the latter as B3,f oligodendrocytes. After 4 to 5 days, the supernatant containing B3,f cells was removed and centrifuged, and the pellet was resuspended in culture medium and replated on polylysine‐coated petri dishes. B3,f oligodendrocytes attached to this surface and extended an intricate network of processes. The purity of the cultures, judged by the number of cells staining with a monoclonal antibody against galactocerebroside was 98–99%. This high degree of cell homogeneity was maintained throughout the life of the cultures. B3,f cells appeared to be highly differentiated and remained so in vitro. This is surmised by the expression of oligodendrocytic characteristic functions such as high levels of CNPase activity typically, 5 μM/min/mgP; high incorporation of H2 35SO4 into sulfatides, an overall lipid metabolism that mimics events associated with myelinogenesis [Szuchet et al, PNAS 80:7019–7023, 1983]; the presence, detected immunocytochemically, of myelin‐associated glycoprotein and myelin basic proteins. It is concluded that this culture system offers an opportunity for studying the biology of interfascicular oligodendrocytes and their interaction with neurons and/or astrocytes. It also should open up a way of examining the relevance of oligodendrocyte polymorphism.
Evidence for an organized lattice in the intercellular space of vestibular sensory cat epithelia
Authors: Favre Daniel , Sans A. 
Published: January 2005

AbstractThe intracellular space between sensory hair cells and nerve endings and between supporting cells of the vestibular epithelia in the cat contains a fine network of microstructures arranged obliquely between the cell membranes of adjacent cells. In situ immersion‐perfusion fixation, electron microscopy complemented by lanthanum negative‐contrast and freeze‐fracture methods suggest that these intercellular structures are tubular with an external diameter between 3 and 6 nm and an internal diameter of 1.5 nm. They could serve as intercytoplasmic tunnels. We discuss the evidence concerning the analogy between the present microchannels and the passageways regularly arranged in the intercellular space of gap‐junctions which would permit the transport of low molecular weight substances from one cell to other.
Cerebral endogenous substrate utilization during the recovery period after profound hypoglycemia
Authors: Benzi G. , Villa R. F. , Dossena M. , Vercesi L. , Gorini A. , Pastoris O. 
Published: January 2005

AbstractMarkedly decreased levels of energy‐rich phosphates were seen in cerebral cortex after severe hypoglycemia, followed by their partial restitution during the recovery period. During hypoglycemia the nonglucose endogenous substrates were provided by glycolytic intermediates, by Krebs cycle intermediates, and by related amino acids. Other potential substrates for brain oxidation were provided by the breakdown of phospholipids and fatty acids.After a 20‐min period of posthypoglycemic recovery, partial restoration of carbohydrates and amino acids occurred, although the amino acid pool size was still reduced. The alterations in phospholipids and fatty acids persisted, while there was a tendency toward normalization of the free fatty acid content. During the posthypoglycemic recovery, treatment with some specific metabolic modulators (6‐aminonicotinamide, hopantenate, uridine, L‐acetylcarnitine) suggested the possibility of an alternative cerebral substrate utilization owing to modulation of the cerebral biochemical machinery. Thus, increased carbohydrate utilization by hopantenate was consistent with decreased lipid breakdown, while increased carbohydrate utilization by uridine was concomitant with decreased amino acid degradation. In this way, decreased cerebral carbohydrate utilization by 6‐aminonicotinamide was associated with increased lipid and amino acid breakdown. Furthermore, the increased loss of cerebral phospholipids and phospholipid‐bound fatty acids by L‐acetylcarnitine occurred in the presence of a large glucose availability and was associated with an extensive reduction of cerebral glycolytic flux.
Astrocyte cell lineage. V. Similarity of astrocytes that form in the presence of dBcAMP in cultures to reactive astrocytes in vivo
Authors: Fedoroff S. , McAuley W. A. J. , Houkle J. D. , Devon R. M. 
Published: January 2005

AbstractThe relationship between astrocytes forming in the presence of dibutyryl cyclic AMP (dBcAMP) in culture and reactive astrocytes responding to a cerebral cortex stab wound was investigated using computerized image analysis (Zeiss IBAS 1) and immunocytochemical staining. The diameters of the nuclei of astrocytes in primary cultures of newborn mouse neopallial cells were compared to those of the nuclei of normal and reactive astrocytes in histological sections of mouse cerebral cortex. We found that the nuclei of astrocytes that formed in the presence of dBcAMP in cultures are significantly larger than those of spontaneously occurring small stellate astrocytes in culture and of normal astrocytes of the cerebral cortex in vivo but corresponded more closely to the nuclei of reactive astrocytes in the area surrounding a stab wound in the cerebral cortex. Large stellate cells formed in the presence of dBcAMP had vimentin and an increase in GFP‐containing intermediate filaments. Formation of reactive astrocytes in vivo is also associated with an increase in both vimentin and GFP‐containing intermediate filaments. These observations indicate a closer relationship of astrocytes formed in the presence of dBcAMP in cultures to the reactive astrocytes in the cerebral cortex than to normal astrocytes. We propose, therefore, that the large stellate astrocytes that form in the presence of dBcAMP be referred to as reactive astrocytes in culture.
Ganglioside biosynthesis in Golgi apparatus: New perspectives on its mechanism
Authors: Yusuf H. K. M. , Pohlentz G. , Sandhoff K. 
Published: January 2005

AbstractThe synthesis of gangliosides GM1 and GM2 in intact rat liver Golgi vesicles is stimulated by phosphatidylglycerol as much as or even more than by detergents (Triton X‐100 and octyglucoside, respectively). The antibiotic tunicamycin, known as an inhibitor of the N‐glycosylation of proteins, strongly inhibits the synthesis of the above gangliosides, in the presence as well as in the absence of the phospholipid. Both phosphatidylglycerol dependence and tunicamycin inhibition disappear when the Golgi vesicles are solubilized by addition of detergents or disrupted by ultrasonication or pretreated with pronase.Transport studies with UDP‐[3H]Gal show that tunicamycin blocks the penetration of the sugar nucleotide into the Golgi vesicles in a concentration‐dependent manner up to 80%. The results show that tunicamycin inhibits ganglioside biosynthesis by blocking the transport of the nucleotide sugar and not by inhibiting the transferase directly.Studies on glycoprotein‐galactosyltransferase with ovalbumin as exogenous acceptor showed that phosphatidylglycerol does not destroy the integrity of the Golgi vesicles. So this phospolipid is an excellent tool for studying ganglioside biosynthesis at optimal transferase activities without solubilizing the Golgi membranes.
Lateral distribution of gangliosides in bilayer membranes: Lipid and ionic effects
Authors: Peters M. W. , Barber K. R. , Grant C. W. M. 
Published: January 2005

AbstractNative Ricinus communis agglutinin (RCA 60) has been used as a visual marker to localize the ganglioside GM1 under a variety of conditions in model membranes. By employing the technique of freeze‐etch electron microscopy, it was possible to resolve membrane structural details down to some 3 nm. The most striking feature was frequent existence of the marker lectin in clusters—presumably reflecting the underlying presence of clustered receptor. This feature persisted at glycolipid concentrations from 0.5 to 7 mol%. It was visible in membranes of single pure phospholipids above and below their phase transition temperatures, in membranes of mixed phospholipids, and in membranes containing cholesterol. The presence of cations, including Ca2+, was not seen to alter the pattern of lectin binding at a resolution of 3 nm. In pure dipalmitoyl phosphatidylcholine, a lining‐up of glycolipid in the “troughs” between ripples in rigid lipid was apparent, in agreement with a similar phenomenon reported by Tillack et al for a neutral glycosphingolipid in pure dimyristoyl phosphatidylcholine [1982: Biochim Biophys Acta 691:261–273]; but this feature was not evident in host matrices composed of several different lipids.
Release of polyunsaturated fatty acids from phospholipids and alteration of brain membrane integrity by oxygen‐derived free radicals
Authors: Hoo Chan P. , Fishman R. A. , Schmidley J. W. , Chen S. F. 
Published: January 2005

AbstractWe studied the effects of oxygen‐derived free radicals on the ultrastructure of brain cortical slices and the release of fatty acids from phospholipids of crude synaptosomes. Xanthine oxidase, hypoxanthine, and ADP‐Fe3+, a free‐radical‐generating system, caused swelling of cellular processes and mitochondria. The oxygen‐derived free radicals also caused the rapid release and accumulation of endogenous polyunsaturated fatty acids (PUFA) from membrane phospholipids as determined by high‐performance liquid chromatography (HPLC). Furthermore, [3H]‐arachidonic acid was also rapidly released from prelabeled phospholipids concomitant with a decrease in radioactivity in various phospholipid fractions. The radioactivities of neutral lipids including diacylglycerols were unchanged by free radicals. These data indicate that the activation of phospholipase A2 and the release of PUFA may have overt effect on membrane integrity and the subsequent development of cellular injury and brain edema.
Growth cones of developing retinal cells in vivo, on culture surfaces, and in collagen matrices
Authors: Harris W.A. , Holt C.E. , Smith T.A. , Gallenson N. 
Published: January 2005

AbstractThe outgrowth of axons from the early retina in vivo is compared with that from retinal explants in two types of culture systems. The normal time course of axonal growth along the primordial optic pathway to the optic tectum is characterized, using tritiated proline and horseradish peroxidase (HRP) as anterograde tracers. The rate of axonal elongation in vivo is estimated to be about 32 μm/hr at 22°C. The HRP technique allows visualization of retinal growth cones in vivo. Observations can thus be made on their microanatomy and on the environment through which they navigate. The growth cones of retinal ganglion cells in the embryo have lamellipodia and fairly short filopodia ( ∼ 10 μm) which are directed forward. The growth cones are found near the pial surface of the brain but do not seem to maintain contact with it.Two culture systems were developed to investigate axonal pathways in vitro. In the first, different substrates and culture media were explored. Results indicate that growth cones prefer a polyornithine substrate over a collagen one. The media that promotes the best neurite outgrowth consists of L15 (60%), fetal calf serum (10%) and Xenopus embryo extract (1 mg/ml). Time‐lapse video monitoring of substrate cultures reveals an average rate of outgrowth of about 18 μm/hr with great variability. The growth cones in these cultures are large, flattened, and complex compared to those in vivo, and their filopodia extend in many different directions.The second culture system is a collagen gel infiltrated with growth medium. In these conditions neurite outgrowth more closely mimics that in vivo. The rate is faster than on substrates, and the growth cones appear morphologically similar to those in the embryo. Preliminary experiments using the gel culture system to test for chemotaxis of retinal axons toward their targets failed to demonstrate such an effect.