bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early cytoarchitectonic development of the anlage of the basal nucleus of meynert in the human fetus
Authors: Kračun Ivica , Rösner Harald 
Published: April 2003

AbstractThe present study describes a short period of cytoarchitectonic development of the anlage of the basal nucleus of Meynert between 9 and 15 weeks of gestation (crown‐rump length 42–120 mm). On the basis of temporo‐spatial reconstruction of the cytoarchitectonic pattern within the basal telencephalon it was evident that magnocellular aggregations of the basal telencephalon contain the most differentiated cells in the whole prosencephalon of the 15‐week‐old human fetus. At this stage of development many magnocellular islands can be observed in the sublenticular region. However, it seems that they are in antero‐posterioral continuation and the real number of magnocellular islands is much smaller than observed in a single section. The most voluminous magnocellular aggregations are situated around the temporal limb of the anterior commissure and below the ventral pallidal surface in the 15th week of gestation. Between 12 and 15 weeks of gestation, at the most rostral levels, the distinct cell group appeared with unique cytoarchitectonic properties (‘albino cell group’). This cell group is situated close to the ventral putaminal surface within the capsula externa fibres and it corresponds to the subputaminal nucleus of Ayala.
Postnatal maturation of brain cholinergic systems in the precocial murid Acomys cahirinus: Comparison with the altricial rat
Authors: Pintor Annita , Alleva Enrico , Michalek Hanna 
Published: April 2003

AbstractThe spiny mouse (Acomys cahirinus) is the only precocial murid species. It has some neuroanatomical peculiarities such as a relatively thin cerebral cortex and a large hippocampus. The levels of choline acetyltransferase. membrane‐bound acetylcholinesterase and muscarinic receptor sites (measured as [3H]quinuclidynil benzilate binding) were assessed in the whole brain on days 1, 7, 14, 21, 28 and 80 (adult), and compared with those of Wistar rats of the corresponding ages. At birth choline acetyltransferase was significantly higher in spiny mice than in rats but the adult levels were similar, with an overall increase of about 5.2‐ and 14‐fold for the former and the latter species, respectively. Membrane‐bound acetylcholinesterase level and maximal density of muscarinic receptor sites in spiny mice were considerably higher at birth, in contrast adult levels were significantly lower than in rats with a respective overall increase of about 1.5‐ and over 4.5‐fold. The high degree of maturity attained at birth by spiny mice partially depends on the long gestation period. However, if we consider postconception age, the maturation of choline acetyltransferase appears to be delayed at birth in the spiny mice, probably in relation to the lack of external stimulation during intrauterine life. In the cerebral cortex, hippocampus and striatum of adult spiny mice, when compared with the rats, there were similar levels of choline acetyltransferase but lower levels of membrane‐bound acetylcholinesterase and, in the cerebral cortex, lower density of muscarinic receptor sites.
Regional and cellular differences in rat brain protein synthesis in vivo and in slices during development
Authors: Shahbazian F.M. , Jacobs Myron , Lajtha Abel 
Published: April 2003

AbstractWe compared the rate of protein synthesis in immature and adult rat brain In vivo to that in brain slices. After the incorporation of a flooding dose of [14C]valine, In vivo and in brain slices, the label in proteins was measured in CNS regions and in neuron‐ and glia‐enriched fractions. In regions In vivo in the adult, incorporation rates in corpus callosum were lower than in other regions, which were similar: in the young, cerebellum showed the highest rates and hypothalamus and cord the lowest. Since hypothalamus and cord were low in the young, there was no change during development in these two areas; in other areas incorporation rates in young were 2–3 times higher than in adult brain proteins. Incorporation rates in slices were lower than In vivo. In the young, cerebellum, olfactory bulb, and cord were close to In vivo, and other areas in slices from young incorporated at 60–90% of In vivo rates. In adult slices incorporation was 5–15% of that In vivo except in olfactory bulb, where it was 30%. In the cellular fractions, incorporation In vivo in young was close in the neuronal and glial fractions; in adults incorporation rates in neurons were higher, as the decrease in development was less in neurons than astrocytes. In slices in young, astrocytes incorporated amino acids at 100% of the In vivo rates, neurons at 60%; in adult slices, incorporation was at only 4–7% of the In vivo rate.The results show that developmental changes in protein metabolism occur in all brain areas and brain cells, with metabolic rates in young 2–3 times that in adult. Incorporation in vitro is less than In vivo: it is close in immature tissue, but is greatly decreased in adult. Although developmental and postmortem differences in rates of synthesis affect most areas and cells, regional and cellular heterogeneity can be found.
Ontogeny of flash‐evoked potentials in unanesthetized rats
Authors: Rigdon Greg C. , Dyer Robert S. 
Published: April 2003

AbstractThe effects of age and stimulation frequency (0.2/sec, 1.0/sec, 2.0/sec, or 4.0/sec) on flashevoked potentials (FEPs) were investigated in awake, unsedated, unrestrained rats. Animals were tested daily from postnatal day (PND) 8 to PND 20, and every 3 or 4 days thereafter until PND 41. On PND 9, a single negative wave (N1a) was observed following 0.2/sec flash presentation. Animals tested on PND 10 exhibited a positive wave (P2) following the return of peak N1a to baseline. On PND 13 another negative wave (N1) appeared on the leading shoulder of peak N1a. Peak N1 became the dominant negative wave on PND 14. Peak N1a merged into N1 and had disappeared by PND 19. Peak N3 was first observed as a negative shift following peak P2 on PND 15. Peaks N2 and P3 were not observed in the group average waveforms until PND 34. Peak latencies decreased through the fifth postnatal week. Peak amplitudes increased with age until after eye opening (PND 15), but were variable thereafter. No FEPs were observed following higher than 0.2/sec flash presentation until PND 13. Increasing stimulation frequency decreased N1 and P2 peak amplitudes, but had no effect on peak latencies.
Glycinergic systems in the brain stem of developing and adult mice: Effects of taurine
Authors: Kontro Pirjo , Oja Simo S. 
Published: April 2003

AbstractThe release of glycine from slices of the brain stem and binding of strychnine to brain stem membranes were characterized in adult and developing mice. Spontaneous glycine efflux was markedly facilitated by homoexchange with exogenous glycine and moderately by heteroexchange with taurine. Potassium stimulation released more glycine from brain stem slices from adult than from 7‐day‐old mice. Potassium‐stimulated glycine release was also potentiated by glycine and by the novel anticonvulsant taurine derivatives. One population of strychnine‐binding sites was found in both mature and immature brain stem. The number of binding sites increased with age, whereas the affinity of the sites for strychnine remained the same. The glycine inhibition was stronger in adult than in developing mice. In the presence of taurine the affinity for strychnine decreased without any change in the maximal binding capacity, suggesting a competitive type of inhibition. The binding constant and maximal binding capacity of strychnine increased in the presence of NaCl (200 mM) both in adult and 7‐day‐old mice. The calculated IC50 values for displacement of strychnine binding by glycine, taurine and β‐alanine were higher in the presence than in the absence of sodium. The results show that the evoked release of glycine and the number of binding sites of strychnine increase during postnatal development in the mouse but that their characteristics do not change.
Development of axonal‐oligodendroglial relationships and junctions during myelination of the optic nerve
Authors: Wiggins Richard C. , Chongjie Guo , Delaney Courtney , Samorajski Thaddeus 
Published: April 2003

AbstractThe early stages of myelination were examined in optic nerves of rats aged 12–15 days. The initial association between oligodendroglial processes and bare axons involves no junctional specialization, as the axoglial extracellular space remains unaltered. Following ensheathment by a collar of glial cytoplasm, at least one full rotation of mesaxon was evident before compact myelin formed. Furthermore, myelin was generally evident before a second rotation was completed. In longitudinal sections, an axoglial junction was always observed beginning on the first paranodal loop, continuing through to the last (or outermost) loop. Thus, the formation of myelin and elaboration of a junctional complex in the paranodal region follow a promyelination phase and appear to be synchronous (and possibly related) events. Although the paranodal plasmalemma and axolemma are in close apposition, there is a material in the extracellular space that precipitates phosphotungstic acid, a characteristic that appears to be featured in a number of different types of cell junctions.
Effects of Trembler mouse serum and laminin on oligodendrocyte proliferation and differentiation in culture
Authors: Hantaz‐Ambroise Djennet , Vigny Marc , Alliot Françoise 
Published: April 2003

AbstractOligodendrocytes in primary cultures derived from rat embryo spinal cord were examined in control medium and in Trembler mouse serum (TMS)‐supplemented medium. The Oligodendrocytes were identified on the basis of the synthesis and surface expression of galactocerebrosides revealed by a monoclonal antibody directed against this component. We noticed two effects of TMS compared to control mouse serum. First, our results revealed that in TMS medium there is a mitogenic response of galactocerebroside (GalC)‐positive cells. Second, in the presence of TMS, Oligodendrocytes do not develop processes as they do in the presence of normal mouse serum. When laminin, a basal lamina component was added to TMS medium, GalC+ Oligodendrocytes decreased in number and differentiation was normal. Possible explanations of the effects of TMS and laminin on oligodendrocyte proliferation and differentiation are discussed.
Cathepsin D and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase in developing human foetal brain
Authors: Mahajan R. G. , Mandal S. , Mukherjee K. L. 
Published: April 2003

AbstractThree peaks of proteinases were observed with hemoglobin, bovine serum albumin and casein as substrates at the pH of 3.5, 6.5 and 8.5, in prenatal human cerebral cortex. Cathepsin D (EC 3.4.23.5) was the most prominent, with hemoglobin as the preferred substrate. The enzyme was partially purified by Concanavalin A — Sepharose affinity chromatography and the nature of the active site was assessed with proteinase inhibitors. Inhibitor studies showed that similar to pepstatin A, benzethonium chloride was also strongly inhibitory to the enzyme. The distribution of cathepsin D, a neuronal marker, and 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase (EC 3.1.4.37), a oligodendroglial marker in foetal brain regions with increasing gestation revealed that neurogenesis and gliogenesis occur concomitantly from earlier periods of gestation. Glial marker acquisition was particularly high in medulla and in spinal cord between 20 and 25 weeks of gestation.
Neuronal aggregation and neurotransmitter regulation: Partial purification and characterization of a membrane‐derived factor
Authors: Adler Joshua E. 
Published: April 2003

AbstractCell membrane contact induces marked differential changes in neurotransmitter expression. In cultures of virtually pure dissociated sympathetic neurons, when such contact is provided by either high cell densities or addition of membranes derived from specific tissues, there is a marked increase in cell‐specific content of substance P and de novo induction of choline acetyltransferase. To identify molecular mechanisms underlying regulation of transmitter expression by neuronal aggregation and membrane contact, we have begun to isolate and characterize a membrane‐associated factor responsible for stimulation of choline acetyltransferase activity. The factor was found in substantial quantities in membranes from adult rat spinal cord as well as from sympathetic and sensory ganglia. Ionic mechanisms were employed to extract transmitter‐inducing activity from spinal cord membranes in soluble form. The solubilized factor was then partially purified by ion exchange and gel filtration chromatography. It appears to be an extrinsic (non‐integral) protein with an apparent molecular weight of 27. It is inactivated by trypsin and chymotrypsin, but is only moderately sensitive to heat inactivation, retaining activity at 60°C but not at 90°C. Neuronal perikaryal contact via aggregation represents a critical mechanism by which neurons themselves may influence phenotypic expression. Membrane localization of the factor provides a means by which cell contact may regulate transmitter expression.
Cytochrome c oxidase during human fetal development
Authors: Moggio Maurizio , Bresolin Nereo , Scarpini Elio , Adobbati Laura , Prelle Alessandro , Gallanti Andrea , Bet Luciano , Fortunato Francesco , Pellegrini Giulio , Scarlato Guglielmo 
Published: April 2003

AbstractHistochemical, biochemical and immunologic analysis of cytochrome c oxidase (COX) in skeletal muscle, heart and kidney during human fetal development was performed. COX histochemical activity was present only in few muscle fibres from the 11th to the 20th week of gestation. At the same developmental stage intrafusal muscle fibres, heart and kidney already showed strong activity. At the 28th week of gestation muscular COX activity was present in about 90% of the fibres. Tissue biochemical analysis confirmed these histochemical findings. Histochemical and biochemical findings compared to the immunocytochemical results and ELISA indicate that COX activity parallels the progressive synthesis of the enzyme in each tissue.
Ontogeny of the metencephalic, mesencephalic and diencephalic content of catecholamines as measured by high performance liquid chromatography with electrochemical detection
Authors: Parés‐Herbuté N. , Tapia‐Arancibia L. , Astier H. 
Published: April 2003

AbstractDevelopmental changes in norepinephrine (NE), dopamine (DA) and epinephrine (E) contents of the rat metencephalon, mesencephalon and diencephalon, have been measured by high performance liquid chromatography with electrochemical detection, from fetal stages (E15 or E17 to E21) to postnatal days (P0 to P30) and compared to the adult levels. The data show a biphasic pattern in NE changes of the three brain areas, with a first increase in the late prenatal period, followed by a further development from PO to P18, thus reaching the adult levels. A similar pattern of development is found for the mesencephalic and diencephalic DA contents. The E levels of the diencephalon are very low in comparison to the NE and DA concentrations, but present a gradual increase from E17 to P18. The results correlate with the development of catecholamine systems in brain area as measured by other methodological approaches.
Developing rat cerebellum—III Effects of abnormal thyroid states and undernutrition on gangliosides
Authors: Vitiello F. , Clos J. , Di Benedetta C. , Gombos G. 
Published: April 2003

AbstractAlteration of rat postnatal cerebellar development produced by undernutrition, thyroxine treatment and thyroid deficiency also involves ganglioside deposition. The distribution of the different ganglioside types is apparently unaffected but quantitative alterations are present that reflect the reduction of cell number and cell process surface in the adult, and either acceleration or slowing down or reduction of cell formation and maturation occurring during cerebellar development in the three experimental situations.
Effects of glycosaminoglycans and proteinase inhibitors on astroglia‐induced detachment of cultured rat cerebellar neurons
Authors: Gilad Gad M. , Dahl Doris , Gilad Varda H. 
Published: April 2003

AbstractNeurons in mixed primary embryonic CNS cultures degenerate secondary to their detachment from the substratum. The present study demonstrates that in primary cultures of postnatal cerebellum, detachment of neurons can be prevented by antiproliferative drugs which inhibit the growth of astroglia. Several types of proteinase inhibitors did not affect the process of detachment. However, among several types of glycosaminoglycans, heparan sulfate and to a lesser degree heparin, could reversibly inhibit neuron detachment without causing morphological changes of astroglia. The enzymes heparitinase and heparinase caused neuron detachment but only within the first 24–48 hr after plating and not in older cultures. We conclude: (1) cerebellar interneurons in culture are not dependent on astroglia for their survival; (2) astroglia are most probably responsible for neuron detachment via a membrane associated activity and (3) heparan sulfate‐like glycosaminoglycans are important in neuronsubstratum attachment.
Embryogenesis of the avian iris sphincter muscle: in vivo and in vitro studies
Authors: Peirone Saverio M. , Sisto‐Daneo Laura , Filogamo Guido 
Published: April 2003

AbstractThe histogenesis of iris sphincter muscle was studied in birds. Chick embryo iris “anlagen”, aged from 3 days (st. 18 H.H.) to hatching, were examined. At the 4th day (st. 24 H.H.), nerve fibers were observed in the mesenchyme of the inferotemporal quadrant of the optic cup near the colobomic fissure. Among the mesenchymal cells, there were cells characterized by AChE activity, presence of desmin filaments, exhibiting ACh receptors, and ultrastructurally similar to the presumptive skeletal myoblasts. One day later (st. 27 H.H.), these myoblasts could be cultivated. The formation of myotubes began between 10 and 12 days. From 9 to 14 days, cells left the anterior epithelium of the iris to give rise to the smooth iris muscle; during this evolution some epithelial cells fused with the myotubes taking part in the histogenesis of striated muscle. The possibility of a neurogenic determination for the iris skeletal muscle is discussed.
Effects of tunicamycin on the avoidance reaction of epidermis by sensory neurites in co‐cultures
Authors: Fichard Agnes , Verna Jean‐Marc , Saxod Raymond 
Published: April 2003

AbstractIn 7‐day chick embryo dorsal root ganglia and epidermis or dermis co‐cultures, nerve fibres establish contacts with dermis while avoiding epidermis. Previous results have indicated that factor(s) secreted by epidermis could be involved in this avoidance reaction. The present study demonstrates that the avoidance reaction is abolished when epidermal cells are treated by the N‐linked glycoproteins synthesis inhibitor, tunicamycin. The same result is obtained after monensin treatment. The epidermal cell viability, development and total protein secretion are not significantly affected by tunicamycin, as demonstrated by trypan blue exclusion, electron microscopy and SDS‐PAGE electrophoresis after 35S‐methionine labelling. It has thus been concluded that the avoidance factor is glycoproteic in nature. It is also suggested that this factor possibly contains chondroitin‐6‐sulphate moieties.
Prenatal phenytoin exposure decreases neuronal membrane order in rat offspring hippocampus
Authors: Vorhees Charles V. , Rauch Scott L. , Hitzemann Robert J. 
Published: April 2003

AbstractPregnant Sprague‐Dawley CD rats were administered 0 or 200 mg/kg of phenytoin by gavage on days 7–18 of gestation, with controls pair‐fed to the phenytoin exposed dams. At birth, litter sizes were standardized to 10, balancing for sex, and were reared by their biological dams until either day 3 or 28. At each of these ages half of the litters from each group were used to determine synaptic plasma membrane order in selected brain regions (cerebellum, cortex, hippocampus) by fluorescence polarization using the probe 1,6‐diphenyl‐1,3,5‐hexatriene (DPH). No significant differences in membrane anisotropy were noted in 3‐day‐old phenytoin offspring, but a reduction in anisotropy in 28‐day‐old phenytoin offspring hippocampal regions was observed. The effect was specific in that no changes were found in the cerebellum or cortex at this age. The magnitude of the change corresponded to an approximately 3–5°C increase in temperature and to changes produced by other known membrane disordering agents, such as ethanol. The data, together with previous findings of memory impairments in phenytoin offspring, support an association between the hippocampal membrane disordering effect and functional impairments produced by prenatal phenytoin exposure.
Substance P‐like immunoreactivity in human prenatal hippocampal formation
Authors: Del Fiacco M. , Diana A. , Floris A. , Quartu M. 
Published: April 2003

AbstractPresence and localization of substance P‐like immunoreactive neuronal structures in human hippocampal formation during prenatal stages of ontogenesis are reported. In fetuses at 16 and 17 weeks of gestation immunoreactivity is very scarce and represented only by sporadic fibres in Ammon's horn and the entorhinal area. In specimens at 25 and 26 weeks of gestation, more or less intensely labelled perikarya of different morphology are easily detectable in deep layers of Ammon's horn and the hilus of fascia dentata. Immunoreactive beaded fibres are also present at this stage. The possibility of the existence of a substance P‐containing extrinsic projection to Ammon's horn is pointed out.
Acidic and basic fibroblast growth factor levels in spinal cord cultures are not regulated by alterations in heparan sulfate proteoglycan expression
Authors: Whittemore Scott R. , White Linda A. , Sanon Henry R. 
Published: April 2003

AbstractThe present study was undertaken to assess both the levels of acidic and basic fibroblast growth factors in spinal cord cultures and to determine how they were presented to responsive cells. Western blots detected a single acidic fibroblast growth factor‐like protein (17 kDa) and two (18 kDa, 24 kDa) basic fibroblast growth factor‐immunoreactive proteins, the levels of which varied with the antibody used. Levels of all three proteins were unaltered in cultures grown in the presence of a mitotic inhibitor, which greatly reduced the number of astrocytes. Cell blots showed increased survival of spinal cord neurons at Mr that corresponded with the three proteins detected immunologically. Solubilized cultures separated on a P100 column showed mitogenic activity for NIH3T3 cells from 17–18 and 24 kDa fractions. Treatment of the cultures with heparitinase did not decrease the levels of acidic and basic fibroblast growth factors detected by Western blots, suggesting that these proteins were not associated with extracellular membrane heparan sulfate proteoglycans. The major fraction of both proteins appeared to be intracellular with a minor amount complexed with extracellular matrix proteins. An inhibitor of xylose‐linked proteoglycan synthesis significantly altered heparan sulfate proteoglycan deposition into extracellular matrix, but did not alter the levels of acidic or basic fibroblast growth factors detected by Western blots, or the levels of choline acetyltransferase, glutamic acid decarboxylase, or aspartate aminotransferase activities. These results indicate that both acidic and basic fibroblast growth factors are stored predominantly intracellularly, with only a minor fraction complexed with extracellular proteins. We suggest that these intracellular proteins may be released following injury in the CNS and mediate a cascade of neuroprotective events.