bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersion and distribution of organically modified montmorillonite in nylon‐66 matrix
Authors: Yu Zhong‐Zhen , Yang Mingshu , Zhang Qingxin , Zhao Chungui , Mai Yiu‐Wing 
Published: April 2003

AbstractNylon‐66 nanocomposites were prepared by melt‐compounding nylon‐66 with an alkyl ammonium surfactant pretreated montmorillonite (MMT). The thermal stability of the organic MMT powders was measured by thermogravimetric analysis. The decomposition of the surfactant on the MMT occurred from 200 to 500 °C. The low onset decomposition temperature of the organic MMT is one shortcoming when it is used to prepare polymer nanocomposites at high melt‐compounding temperatures. To provide greater property enhancement and better thermal stability of the polymer/MMT nanocomposites, it is necessary to develop MMT modified with more thermally stable surfactants. The dispersion and spatial distribution of the organic MMT layers in the nylon‐66 matrix were characterized by X‐ray diffraction. The organic MMT layers were exfoliated but not randomly dispersed in the nylon‐66 matrix. A model was proposed to describe the spatial distribution of the organic MMT layers in an injection‐molded rectangular bar of nylon‐66/organic MMT nanocomposites. Most organic MMT layers were oriented in the injection‐molding direction. Layers near the four surfaces of the bar were parallel to their corresponding surfaces; whereas those in the bulk differed from the near‐surface layers and rotated themselves about the injection‐molding direction. The influence of the spatial distribution of the organic MMT on crystallization of nylon‐66 was also investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1234–1243, 2003
On the Heisenberg principle, namely on the information‐disturbance trade‐off in a quantum measurement
Authors: D'Ariano G.M. 
Published: April 2003

AbstractCommon misconceptions on the Heisenberg principle are reviewed, and the original spirit of the principle is reestablished in terms of the trade‐off between information retrieved by a measurement and disturbance on the measured system. After analyzing the possibility of probabilistically reversible measurements, along with erasure of information and undoing of disturbance, general information‐disturbance trade‐offs are presented, where the disturbance of the measurement is related to the possibility in principle of undoing its effect.
Smooth muscle relaxant effect of kaurenoic acid, a diterpene from Copaifera langsdorfﬁi on rat uterus in vitro
Authors: de Alencar Cunha K. M. , Paiva L. A. F. , Santos F. A. , Gramosa N. V. , Silveira E. R. , Rao V. S. N. 
Published: April 2003

AbstractThe effect of kaurenoic acid, a diterpene isolated from the oleo‐resin of the popular medicinal plant Copaifera langsdorfﬁi (Leguminaceae), was analysed on rat uterine muscle responsiveness to various drugs in vitro. Cumulative concentration‐response curves to acetylcholine and oxytocin were obtained before and after incubation of uterine segments with up to 160 µm of kaurenoic acid. The maximal contractile response (Emax) evoked by these agonists was inhibited by kaurenoic acid in a concentration‐related manner; at 160 µm, kaurenoic acid depressed the Emax of oxytocin and acetylcholine by 83% and 91%, respectively. The relaxation caused by kaurenoic acid on oxytocin‐induced contraction was unaffected in the presence of tetraethyl ammonium, a compound that blocks the calcium activated potassium channels. It was partially reversed by glibenclamide (10‐5 m), an ATP‐sensitive potassium channel blocker. Also, kaurenoic acid at 160 µm concentration was found to inhibit signiﬁcantly the CaCl2‐evoked contractile responses in a medium of high potassium and zero calcium. Furthermore, kaurenoic acid was found to relax the sustained tonic contraction induced by acetylcholine, oxytocin, BaCl2 and KCl in a concentration‐dependent way. However, KCl‐induced tonic contraction was only weakly inhibited by kaurenoic acid. These data indicate that the diterpene, kaurenoic acid, exerts a uterine relaxant effect acting principally through calcium blockade and in part, by the opening of ATP‐sensitive potassium channels. Copyright © 2003 John Wiley & Sons, Ltd.
Distribution of the neural antigen BSP‐2 in the cerebellum during development
Authors: Langley O. K. , Gombos G. , Hirn M. , Goridis C. 
Published: April 2003

AbstractThe monoclonal antibody anti‐BSP‐2 recognizes three glycosylated peptide chains of 180,000, 140,000 and 120,000 daltons in extracts from adult mouse forebrain and cerebellum. In extracts of embryonic or neonatal brain, it recognizes a different form, migrating as a broad band of higher molecular weight on SDS polyacrylamide gels. This report describes the distribution of the antigen BSP‐2 in developing mouse cerebella using a sensitive immunoperoxidase technique at the electron microscope level. As early as 3 days after birth the antigen can be detected on the surface of all cerebellar neurons, including neuroblasts in the external granular layer, basket and stellate neurons and Purkinje cells. In addition, radial glial fibres (astrocytes) terminating on the pial surface contain BSP‐2. At later stages a pronounced surface labelling of parallel fibres is observed. Migrating granule cell perikaryal membranes possess the glycoprotein. The results are discussed in relation to the apparent identity of BSP‐2 and the cell adhesion molecule N‐CAM and its physiological properties.
Cultured embryonic non‐innervated mouse muzzle is capable of generating a whisker pattern
Authors: Andrés Filipe L. , Van der Loos Hendrik 
Published: April 2003

AbstractThe whisker pattern on the muzzle of the mouse is mapped in the contralateral parietal neocortex, each whisker follicle projecting to its own multineuronal unit (‘barrel’). To determine the role, if any, of the peripheral innervation in the establishment of the vibrissal array, we cultured non‐innervated prospective whiskerpads from 9‐ and 10‐day‐old embryos, mostly on chorioallantoic membrane. The results show that skin, alone, is capable of generating the whisker pattern, thus adducing a strong argument for the hypothesis that the central brain maps have their origin in the periphery.
Prenatal and postnatal development of synapses and acetylcholinesterase staining in the dentate gyrus of the rhesus monkey
Authors: Vijayan Vijaya K. 
Published: April 2003

AbstractMorphogenesis, distribution of cholinergic enzyme acetylcholinesterase and synaptogenesis in the dentate gyrus of the rhesus monkey during the pre‐ and postnatal periods of development were examined using histological, histochemical and ultrastructural methods. The pattern of neuronal differentiation in the dentate gyrus demonstrated distinct superficial‐to‐deep and lateral‐to‐medial gradients. The histochemical reaction for acetylcholinesterase was present on gestation day 120 as minimal staining in the supragranular band and in the inner one‐third of the dentate molecular layer. At term, the laminar distribution of the enzyme assumed mature pattern although considerable enhancement in staining intensity was achieved postnatally. At term and at 9 months of postnatal age, the most pronounced enzyme activity was found in the supragranular band and in the inner one‐third of the molecular layer. Synaptogenesis in the dentate molecular layer was characterized by the early formation of axo‐dendritic contacts on dendritic trunks and branches followed by the appearance of synapses on simple and complex spines. Spines were detected infrequently on gestation day 132. On day 148, they ranged in morphology from short stubby protrusions to pedunculated, triangular processes. The majority of the spines exhibited flat postsynaptic surfaces. Complex, synapse‐bearing U‐ and W‐shaped spines were observed rarely at this age but appeared more frequently at term and at 15 months of postnatal age. However, at all ages, including 15 months postnatally, synapses on flat‐surfaced simple spines predominated. Most synapses were of the asymmetric variety.With certain exceptions, these features of development of the rhesus dentate gyrus resemble the reported patterns of postnatal ontogenesis of this structure in the rat. However, the ingrowth of cholinergic afferents and the major modifications in synapse structure occur prenatally in the rhesus monkey during the second half of the gestation period. This temporal difference between the two species should receive consideration in the planning of neuroplasticity experiments designed to explore lesion‐induced adaptations in afferent growth and synaptogenesis in the rhesus dentate gyrus.
Ontogenetic changes of the soluble and membrane‐bound D2 glycoprotein in rat forebrain
Authors: Gennarini Gianfranco , Corsi Patrizia , Pavia Rosalia , Vitiello Francesco , Di Benedetta Carlo 
Published: April 2003

AbstractA soluble form of the D2 glycoprotein, detected in the rat brain hypotonic extract, is described. Its specific relative concentration did not differ significantly in the three examined cerebral regions (forebrain, brainstem and cerebellum), while in the cerebellum the membrane‐bound form was about three and four times more concentrated than in the forebrain and brainstem, respectively. No sizeable developmental variations of the soluble D2 concentration could be detected in forebrain, whereas the amount of the membrane‐bound protein rose from birth to postnatal day 6 and then decreased to the adult value (about 40% of the newborn concentration). Ontogenetic modifications of the membranous D2 glycans (studied through the binding of the molecule to several lectins) occur around postnatal day 18 when the binding to Ricinus communis lectin, specific for galactose, becomes evident. At all ages both soluble and membrane‐bound forms bind to Concanavalin A, specific for mannose and glucose, and to wheat germ agglutinin, specific for N‐acetylglucosamine, while the lack of binding to Ulex europeus lectin suggests the absence of discrete amount of fucose. The results are discussed in relation to the possible involvement of D2 glycoprotein in cell‐to‐cell adhesion.
Influence of brain extract and dibutyryl cyclic AMP on the amount of carbonic anhydrase in primary glial cell cultures from newborn rat brain
Authors: Delaunoy J. P. , Hog F. , Sensenbrenner M. 
Published: April 2003

AbstractThe effect of brain extracts from rat and beef, and of 2′,5′‐dibutyryl cyclic AMP on the CAII content was investigated in rat primary glial cultures maintained in serum‐containing or serum‐free medium. All cultures contained a mixed population of oligodendroglial and astroglial cells, but under certain conditions the cultures were highly enriched in oligodendroglial cells. An immunocytochemical positive reaction to CAII was observed in oligodendrocytes, while astrocytes were not stained. The content of CAII per culture and per oligodendroglial cell was higher after treatment of the culture with soluble brain extract and a partially purified fraction. A combined autoradiographic‐ immunohistochemical study, after [3H]thymidine incorporation and staining for CAII, showed that under the influence of rat brain extract the number of mitotic CAII positive cells was greater at day 11 compared to control cultures. But the proliferation rate decreased with time in culture after brain extract treatment and the number of mitotic CAII positive cells became far below that of controls. Since at the same time CAII quantity per cell was higher in the treated ones it is suggested that brain extract not only influences the proliferation of oligodendroglial cells, but also their maturation. The addition of 2′,5′‐dibutyryl cyclic AMP had no effect on oligodendroglial cells and the amount of CAII in the cultures was not affected. It is discussed that agents, which stimulate 3′,5′‐cyclic AMP content, may not influence the CAII content, but may stimulate the enzymatic activity.
Properties of γ‐glutamyltransferase in developing rat brain
Authors: Pajari M. 
Published: April 2003

AbstractThe activity and properties of brain γ‐glutamyltransferase (EC 2.3,2.2) were studied in 7‐, 14‐and 90‐day‐old rats. The enzyme activity was highest in the pons‐medulla and lowest in the cerebellum in each age group. The activity of glycylglycine, 10 protein amino acids, GABA and taurine as acceptor of the γ‐glutamyl group was studied with 7‐day‐old and adult rats. The best acceptors were glycylglycine, lysine and methionine and the poorest taurine, valine and isoleucine. The relative acceptor activity of lysine changed most during development. Km for the γ‐glutamyl donor, γ‐glutamyl‐p‐nitroanilide, with glycylglycine was about 3 mM in all experimental groups. It did not change during development but V increased about fivefold in all brain areas studied. A mixture of serine and borate strongly inhibited γ‐glutamyltransferase in each age group. Potassium and magnesium ions had no measurable effect on the enzyme activity but sodium ions were stimulatory.
Some properties of uridine‐5′‐diphospho‐N‐acetylgalactosamine:Hematoside N‐acetylgalactosaminyltransferase at early and late stages of embryonic development of chicken retina
Authors: Maccioni H.J.F. , Panzetta P. , Arrieta D. 
Published: April 2003

AbstractSome properties of the uridine‐5′‐diphospho‐N‐acetylgalactosamine:hematoside N‐acetylgalactosaminyltransferase were studied in retina tissue from chick embryos at 7 and 14 days of development. The Vmax was about 6‐fold higher in retinas from 14 day embryos than in retinas from 7 day embryos. No differences were found either in the apparent Michaelis constant for both donor nucleotide and acceptor glycolipid, or in the optimal detergent concentration, or in the stability upon storage at −14°C or heating at 50°C. Mixtures of homogenates of retinas from 7 day and from 14 day embryos gave the activity values expected for samples free of effectors diffusible and in excess. From experiments of partial delipidation of retina homogenates and reconstitution with lipid from retina homogenates from one or the other age, no indications were found that the activity was modulated by developmental changes in the lipid environment of the enzyme. Taken together, the results suggest that the increase of activity during development was not due to qualitative changes in the catalytic characteristics of the enzyme.
In Purkinje cell dendrites of the young rat, thyroid hormone controls the resistance of microtubules to fixation at low temperature
Authors: Faivre Catherine , Legrand Christiane , Rabié Alain 
Published: April 2003

AbstractMicrotubules were studied in parallel fibres and Purkinje cell dendrites of 14‐day‐old normal and propylthiouracil‐treated rats after fixation of the cerebellum at room and low temperature (4°C). In both control and propylthiouracil‐treated animals, nearly all the microtubules of parallel fibres disappeared after fixation at low temperature. In Purkinje cell dendrites of control animals, 60% of the microtubules persisted at low temperature. Propylthiouracil treatment led to a 78% decrease in the density of these cold‐stable microtubules. In contrast, the density of cold‐labile microtubules remained normal. Administration of low doses of thyroxine to the propylthiouracil‐treated rats produced a rapid increase in the density of cold‐labile microtubules, but long‐term treatment with the hormone was necessary to obtain normal density of cold‐stable microtubules. Thyroid hormone thus seems to regulate some properties of microtubules involved in their resistance to fixation at low temperature. These properties could be of importance in growth and branching of dendrites.
Development of mouse spinal cord in tissue culture—III. Quantification of neuron development in neural tube microfragment cultures
Authors: Houle John , Fedoroff Sergey 
Published: April 2003

AbstractMouse neural tube development in vitro was examined following the isolation and culturing of specific regions of the neural tube. Developmental characteristics of neuron formation and differentiation were assessed both quantitatively and qualitatively.A 1 mm length of embryonic day 10 mouse neural tube was cut into 32 microfragments of equal size and cultured on collagen coated cover‐slips. Neuronal cells were observed to emerge after 3 days in culture and to migrate away from the fragment upon an immature astroglial precursor cell layer that had begun to form within the first 24 h of culturing. The extent of neuronal migration, the density and total number of neurons per outgrowth zone, and the size distribution of neurons was quantitated after 21 days in culture. Three distinct patterns of neuronal outgrowth (Types II, III and IV) could be observed with a fourth pattern (Type I) best described as being neuron free. Neuron free outgrowth zones (Type 1) were comprized totally of glial cells and represented approximately 10% of the outgrowth zones examined. Characteristics of Type II outgrowth zones were a relatively restricted neuronal migration and a predominance (85%) of small neurons (< 10μm diameter) scattered around the outgrowth zone. In contrast the area of Type III outgrowth zones was twice that of the Type II, with a neuronal density 2.5 times greater, composed of a near equal proportion of small to medium sized (10–18 μm) neurons. The neuronal density and extent of migration of Type IV zones was similar to that of Type II zones; however the neurons of this fragment type were primarily medium and large sized neurons.In a second experiment the brachial region of E10 neural tube was sectioned into dorsal and ventral halves and microfragments from each half were cultured separately. Dorsal fragments produced primarily Type I and Type II outgrowth zones, and never a Type IV. In contrast, ventral fragments produced primarily Type III and Type IV zones with a small proportion of Type II zones.The results indicate that neuronal precursor cells in vitro maintain an adherence to patterns of neurogenesis programmed in vivo during early stages of neural tube development. The present culture system thus provides a means for the study of the expression in vitro of specific patterns of neuronal development and of the possible environmental influences (epigenetic factors) upon these patterns.
Alterations in the development of the main olfactory bulb of the mouse after ethanol exposure
Authors: Nyouist‐Battie Cynthia , Gochee Angel 
Published: April 2003

AbstractThe effect of ethanol on the development of the main olfactory bulb (OB) was examined by light and electron microscopy in 21‐day‐old Swiss mice (CD‐1), exposed to ethanol from embryonic day 13 to postnatal day 21. Two control groups were included in the study to rule out changes due to malnourishment: a normal control group, whose dams were fed rodent lab chow throughout the study and a pairfed group, whose dams were fed the same amount of liquid diet as the dams in the ethanol group but with sucrose replacement of ethanol. Somatic growth, measured by length and body weight, was retarded to the same degree in ethanol and pairfed mice, indicating a similar level of malnourishment in both groups without an additional ethanol effect. The most striking change in olfactory bulb development was the stunted growth of this structure in the ethanol‐exposed animals with reductions in the volume of the glomerular. external plexiform and granular cell layers. The laminar organization and cellular cytoarchitecture were not substantially altered by ethanol or malnourishment except for a retarded migration of the periglomerular cells in the ethanol‐treated group. Examination of synaptogenesis in the external plexiform layer (EPL) of olfactory bulb from 21‐day‐old mice in the three groups revealed no treatment‐related changes in synaptic structure, appositional length or ratios of the two dominant type of EPL synapses, which are formed between dendrites of the output neurons (mitral and tufted cells) and granule cells. However, morphometric analysis revealed elevated densities of both synaptic types in the ethanol‐exposed group but with no change in the total synaptic number per olfactory bulb. The results suggest that ethanol exposure of mice after the latter half of gestation and during the postnatal period primarily affects the growth of the olfactory bulb probably by decreasing neuronal cell growth, and/or proliferation but has little affect on other aspects of maturation such as formation of cortical structure, differentiation and synaptogenesis.
Microtubules and neurofilaments in the sciatic nerve fibres of the developing rat: Effects of thyroid deficiency
Authors: Marc Christine , Rabié Alain 
Published: April 2003

AbstractMicrotubules and neurofilaments were counted in cross‐sections of the sciatic nerve fibres of young rats at various stages of development. A linear relationship was found between the numbers of microtubules and neurofilaments and the size of the fibre. The number of microtubules progressively increased during the first two postnatal weeks. Neurofilaments appeared slightly later than microtubules. In thyroid deficiency, the number of microtubules was diminished. The number of neurofilaments was not markedly affected. The ratio of neurofilaments to microtubules was thus increased. The severe retardation of sciatic nerve growth observed in thyroid deficiency might be related to the reduced number of microtubules and to a diminution in fibre plasticity induced by the higher neurofilament to microtubule ratio.
Effects of forskolin on growth and morphology of cultured glial and cerebrovascular endothelial and smooth muscle cells
Authors: Kempski O. , Wroblewska B. , Spatz M. 
Published: April 2003

AbstractThe present experiments were designed to evaluate the effectiveness of forskolin on cAMP production, growth and morphology on cell cultures of glia, endothelium and smooth muscle derived from brain microvessels.Forskolin significantly increased formation of cAMP and decreased incorporation of thymidine in all three cell types. The thymidine incorporation was reduced dose‐dependently with maximal growth inhibition at 100 μM forskolin. A 1 hr preincubation with forskolin abolished thymidine incorporation by cells grown in fetal calf serum (FCS)‐containing media over the following 24 hr.In cerebromicrovascular endothelium and smooth muscle, forskolin caused drastic and immediate changes of cell morphology and F‐actin composition that were reversible. In glial cells, morphological changes were visible only after exposure to forskolin for more than 24 hr. These changes were accompanied by increased staining with antibodies against glial fibrillary acidic protein (GFAP).These findings support the contention of cAMP involvement in growth regulation of these cells and indicate that forskolin might be used as a tool to induce growth arrest and possible differentiation in cell cultures from mammalian brain.
Effects of nerve growth factor on sensory neurons in the chick embryo: A stereological study
Authors: Dimberg Yvonne , Hedlund Kjell‐Olof , Ebendal Ted 
Published: April 2003

AbstractChicken embryos on days 6–13 of incubation received injections of purified βNGF (80 μ/ day) for 3 or 4 days and were then killed. Sensory ganglia were fixed and taken for embedding and sectioning. A stereological method based on unfolding of cell‐diameter frequencies was used to determine the number of neurons of different size in the spinal, trigeminal and nodose ganglia. The total volume of the ganglia was also determined. NGF induced increases in diameter of the neural crest‐derived dorsomedial (DM) neurons in spinal and trigeminal ganglia. Injected NGF did not influence ventrolateral (VL) neurons of neural crest origin in the spinal ganglia nor the ventrolateral neurons of placodal origin in the trigeminal ganglion. The volumes of spinal and trigeminal ganglia increased by 50 and 100%, respectively. The volume of the nodose ganglion and the total number and size of the placodal nodose neurons were unaffected by NGF. The results demonstrate a clear difference in the response to NGF in vivo between smaller and larger sensory neurons.