bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axonal dependency of the postnatal upregulation in neurofilament expression
Authors: Schwartz M. L. , Shneidman P. S. , Bruce J. , Schlaepfer W. W. 
Published: January 2005

AbstractA coordinated up‐regulation in the expression of all three neurofilament (NF) proteins occurs during postnatal development in the rat (Schlaepfer and Bruce, J Neurosci Res [in press], 1990a). In the present study, sciatic nerves were transected in neonatal rats in order to determine the effects of axotomy on the postnatal upregulation of NF expression in neurons of rat dorsal root ganglia (DRG). Left sciatic nerves were transected at postnatal day 3 (P3), 6 (P6), 8 (P8), or 10 (P10). mRNA and protein levels of the light (NF‐L), mid‐sized (NF‐M), and heavy (NF‐H) NF proteins were compared in L4 and L5 DRGs from the transected (left) vs. control (right) sides of the same animals at varying intervals after transection. When nerves were transected at P10, mRNA levels of all three NF proteins declined markedly in the parent DRG neurons, thereby completely interrupting the postnatal upregulation of NF expression. P10 transections also led to widespread chromatolytic changes in axotomized neurons, indistinguishable from those that occur in adult DRG following sciatic nerve transection (Goldstein et al., J Neurosci 7:1586–1594, 1987). Nerve transections at earlier (e.g., P3) neonatal timepoints also led to a decrease of NF expression, but to a lesser extent than that which resulted from a P10 transection. Also, P3 transections caused only minimal chromatolytic changes in the axotomized neurons. Thus, the postnatal upregulation of NF expression is dependent upon axonal continuity and the extent of axonal dependency increases during early postnatal development. These findings support the hypothesis that the postnatal upregulation of NF expression, the axotomy‐induced downregulation of NF expression and the chromatolytic reaction to nerve transection are all dependent upon or responsive to axonal‐ or target cell‐derived signals that are acquired during postnatal maturation.
Rat facial motoneurons express increased levels of calcitonin gene‐related peptide mRNA in response to axotomy
Authors: Haas C. A. , Streit W. J. , Kreutzbeg G. W. 
Published: January 2005

AbstractThe expression andAbteilung localization of the mRNA encoding the calcitonin gene‐related peptide (CGRP) were analyzed in the rat facial nucleus after axotomy by Northern blot analysis and by in situ hybridization histochemistry (ISH) using a synthetic 32P‐labeled oligonucleotide probe. Northern blot analysis revealed the presence of the 1.2 kb CGRP mRNA in RNA extracted from the facial nucleus. This mRNA species was strongly increased after axotomy of the facial nerve. By ISH increased levels of CGRP mRNA were observed as soon as 16 hr after axotomy compared with the unoperated nucleus. CGRP mRNA could be localized in more than 50% of the motoneurons. Three populations of motoneurons with no, moderate, or strong labeling for CGRP mRNA could be distinguished. Peak expression of CGRP mRNA during the first 48 hr was followed by a decline to moderate levels at day 4 after lesion, and to almost basal levels at days 7 and 9. These data demonstrate that axotomy of the facial nerve leads to an early and strong induction of CGRP gene expression in motoneurons of the facial nucleus.
Regulation of β‐nerve growth factor expression by inflammatory mediators in hippocampal cultures
Authors: Friedman W. J. , Lärkfors L. , Ayer‐LeLievre C. , Ebendal T. , Olson L. , Persson H. 
Published: January 2005

AbstractSubstances which regulate expression of nerve growth factor (NGF) were examined in embryonic rat: hippocampal cultures containing both neurons and glial cells. Both cell types expressed NGF mRNA when cultivated in vitro. Lipopolysaccharide, an activator of macrophages, elicited a significant increase in NGF mRNA. Interleukin‐1β evoked a similar increase in NGF mRNA which was accompanied by a rise in NGF protein. The II‐1‐induced increase was partially blocked by indomethacin, suggesting that prostaglandins might mediate this effect. Treatment of the cultures directly with prostaglandin E2 resulted in elevated levels of both NGF mRNA and protein. Thus, agents which promote inflammatory activity appear to increase NGF expression. Moreover, a suppressor of inflammation, dexamethasone, decreased NGF expression. Our observations indicate that a variety of immunomodulators regulate NGF expression in the hippocampus.
Gene delivery to glioma cells in rat brain by grafting of a retrovirus packaging cell line
Authors: Short M. P. , Choi B. C. , Lee J. K. , Malick A. , Breakefield X. O. , Martuza R. L. 
Published: January 2005

AbstractRetrovirus vectors only integrate into the genome of dividing cells and can thus be used to selectively infect tumor cells in the adult rat brain. Gene delivery was assessed by using the retrovirus BAG vector, which bears the Escherichia coli lacZ gene under the MoMLV LTR promoter‐enhancer element, and by histochemical staining for bacterial beta‐galactosidase activity. Direct injection of this vector (90–900 cfu) into the adult rat brain, with or without prior inoculation of C6 glioma cells (2 × 105 cells) resulted in labeling of only a few cells as assessed 1 week later. When the psi 2‐BAG packaging line was grafted into the brain, labeled psi 2‐BAG cells could be found after 1 day, but not after 5 days, following grafting, suggesting that the grafted cells had been rejected and that no endogenous cells had integrated released vector, or that expression of lacZ had been turned off. In contrast, when the psi 2‐BAG packaging line was grafted into a brain region, which had been inoculated previously with rat C6 glioma cells (2 × 105 cells), beta‐galactosidase labeling of these tumor cells, identified by immunocytochemistry for glial fibriliary acidic protein and S100, could be demonstrated 10 days later. Thus, grafting of retrovirus packaging lines into adult brain provides a means to infect tumor cells in situ. The grafted packaging cells may continue to release retrovirus particles for an extended period, thus infecting more cells at the stage of division appropriate for viral integration, as compared to inoculation of the virus alone. Grafting of retrovirus packaging cell lines could be used to selectively deliver “killer” or “suppressor” genes to tumor cells in the brain to curtail their growth.
Preferential uptake and metabolism of docosahexaenoic acid in membrane phospholipids from rod and cone photoreceptor cells of human and monkey retinas
Authors: de Turco E. B. Rodriguez , Gordon W. C. , Peyman G. A. , Bazan N. G. 
Published: January 2005

AbstractThe uptake, metabolism, and cellular distribution of [3H]docosahexaenoic acid (DHA) in human and monkey retinas were studied with biochemical and autoradiographic techniques. In specimens from two human retina biopsies, incubated for 4 hr or 6 hr with [3H]docosahexaenoic acid (110 nM), 80% of the esterified [3H]fatty acid was recovered in phospholipids and the remainder in triacylglycerols and diacylglycerols. The distribution of [3H]DHA in individual phospholipids (PL) was similar in both retinas, with phosphatidylcholine (PC) and phosphatidylethanolamine (PE) accounting for most of the label. A similar labeling profile was observed in glycerolipids from monkey retina, and after 1 hr of incubation, high labeling of phosphatidic acid (PA, 11%) and phosphatidylinositol (PI, 20%) was observed.In both human and monkey retinas, a preferential uptake of [3H]DHA by photoreceptor cells was revealed by autoradiography. Cone photoreceptors showed a slightly higher density of silver grains in their inner segments than did rod photoreceptors. Photoreceptors accounted for 59% and 79% of the total [3H]DHA taken up by the human and monkey retinas, respectively, the remainder being distributed throughout the neural retina. In conclusion, this study shows for the first time that in human and monkey retinas, DHA is taken up with a high degree of selectivity by photoreceptor cells, and then becomes esterified mainly into phospholipids that will be subsequently utilized for the synthesis of new disc membranes.
Age‐related decreases in muscarinic cholinergic receptor binding in the human brain measured with positron emission tomography (PET)
Authors: Dewey S. L. , Volkow N. D. , Logan J. , MacGregor R. R. , Fowler J. S. , Schlyer D. J. , Bendriem B. 
Published: January 2005

AbstractMuscarinic cholinergic Ml and M2 receptors in young and aged adult male volunteers were studied using [N‐11C‐methyl]‐benztropine, a specific muscarinic cholinergic receptor ligand, and high resolution positron emission tomography (PET). A regionally specific pattern of decreased binding was observed in aged volunteers. Using two separate methods of data analysis, thalamic, hippocampal and cerebellar regions showed no decreases in the apparent specific binding of [N‐11C‐methyl]‐benztropine while frontal, parietal, temporal and occipital cortices as well as the corpus striatum showed age related changes in binding that declined (in 82 yrs old subject) to about 50 % of the value obtained from the youngest volunteer (19 yrs). These data suggest that regions high in muscarinic receptor density, the corpus striatum and the cortical mantle, show a greater rate of decline than those areas that have a relatively low number of muscarinic receptors. Furthermore, this study demonstrates the usefulness of PET and [N‐11C‐methyl]‐benztropine for assessing age related regional changes in muscarinic cholinergic receptor binding in the living human brain.
Cellular distribution of transferrin, ferritin, and iron in normal and aged human brains
Authors: Connor J. R. , Menzies S. L. , Martin S. M. St. , Mufson E. J. 
Published: January 2005

AbstractThe iron transport protein, transferrin, and the iron storage protein ferritin were examined immunohistochemically along with iron in a number of brain regions from normal and aged humans. Two age groups were examined: a middle‐aged group (28–49 years), and an older group (60‐90 years). Transferrin, ferritin, and iron are found throughout all brain regions examined, predominantly in the perikaryal cytoplasm of cells that are small and round, fitting the description of oligodendrocytes. These cells are present in the optic nerve and in both the gray and white matter of the cerebral cortex, cerebellum, and olfactory bulb in both age groups. Ferritin is also found in microglial cells in the gray matter of most of these brain regions. In the subcortical regions examined (corpus striatum, hippocampus, amygdala), in addition to oligodendrocytes, astrocytes can frequently be observed that contain transferrin, ferritin, and iron. There is an age‐related alteration in cell labeling: astrocytes in both gray and white matter contained transferrin in the oldest age group, whereas in the younger group the subcortical transferrin immunoreactivity was confined mostly to oligodendrocytes. Ferritin in the subcortical brain regions is also present in astrocytes but is primarily confined to those in the gray matter, even in the oldest age group. Iron is found predominantly in oligodendrocytes, although a few iron‐positive astrocytes and microglia can be identified. These results indicate that (1) normally oligodendrocytes contain much of the iron and iron‐binding proteins found in the brain; and (2) an increase in age is associated with altered cellular distribution of iron‐binding proteins, but the altered distribution is specific to glial cells. These results suggest glial cells may have previously undescribed functions related to metal regulation and sequestration.
Morphologic heterogeneity of human adult astrocytes in culture: Correlation with HLA‐DR expression
Authors: Yong V. W. , Yong F. P. , Olivier A. , Robitaille Y. , Antel J. P. 
Published: January 2005

AbstractHuman adult astrocytes derived from brain surgical resections showed marked morphologic heterogeneity when cultured in vitro, ranging from a flat, fibroblast‐like appearance to process‐bearing cells with little soma cytoplasm. The majority of cells were intermediate in morphology, bearing a prominent cytoplasmic cell body with processes radiating from them. The morphologic heterogeneity was more extensive than that of adult rat astrocytes, and was not correlated with the extent of attendant gliosis in the surgical specimens, or the site of the surgical resection. None of the human astrocytes expressed A2B5, thus preventing their classification on basis of lineage into type 1 or type 2 astrocytes. However, functional differences appear to exist between subpopulations of human astrocytes, since the proportion of process‐bearing human astrocytes that expressed HLA‐DR in vitro was significantly greater than that found for flat astrocytes.
Active polysomes in the axoplasm of the squid giant axon
Authors: Giuditta Antonio , Menichini E. , Capano C. Perrone , Langella M. , Martin R. , Castigli E. , Kaplan B. B. 
Published: January 2005

AbstractAxons and axon terminals are widely believed to lack the capacity to synthesize proteins, relying instead on the delivery of proteins made in the perikaryon. In agreement with this view, axoplasmic proteins synthesized by the isolated giant axon of the squid are believed to derive entirely from periaxonal glial cells. However, squid axoplusm is known to contain the requisite components of an extra‐mitocliondrial protein synthetic system, including protdn factors, tRNAs, rRNAs, and a heterogeneous family of mRNAs. Hence, the giant axon could, in principle, maintain an endogenous protein synthetic capacity. Here, we report that the squid giant axon also contains active polysomes and niRNA, which hybridizes to a riboprobe encoding murine neurofilament protein. Taken together, these findings provide direct evidence that proteins (including the putative neuron‐specific neurofilament protein) are also synthesized de novo in the axonal compartment.
Increased PKA and PKC activities accompany neuronal differentiation of NT2/D1 cells
Authors: Abraham I. , Sampson K. E. , Powers E. A. , Mayo J. K. , Ruff V. A. , Leach K. L. 
Published: January 2005

AbstractAfter retinoic acid treatment, a large percentage of cells of the human embryonal carcinoma cell line NT2/D1 differentiate into neuronal cells. We demonstrate here that the differentiated cells, but not the undifferentiated cells, contain high levels of neurofilament mRNA. We have also measured mRNA, protein, and activity levels of two kinases, cAMP‐dependent protein kinase (PKA) and protein kinase C (PKC), in order to explore the role of protein kinases in the establishment of the differentiated state. RNA levels for the catalytic (Cα and Cβ) subunits of PKA increased after differentiation. Total PKA activity levels increased 7‐fold in the differentiated cells. Parallel with this, a rise in the level of catalytic subunit protein occurred. A 12‐fold induction of Type 2 (β) PKC mRNA levels was observed after neuronal differentiation. Increases in PKC activity and in Type 2 (β) and Type 3 (α) PKC protein levels also accompa nied differentiation. These changes in PKA‐ and PKC‐specific RNA levels and enzyme activity may be necessary for production and maintenance of the differentiated state in these cells.
Microglial cells are a component of the perivascular glia limitans
Authors: Lassmann H. , Zimprich F. , Vass K. , Hickey W. F. 
Published: January 2005

AbstractThe ultrastructural relation between microglial cells and cerebral blood vessels was studied in rat brains by immune electron microscopy using antibodies against the common leukocyte antigen (Oxl), the complement receptor 3 (Ox42), and against class I and class II histocompatibility antigens (MHC antigens; Ox3, Ox6, Oxl8, and I1‐69). Microglial cell processes were found incorporated between the astrocytic foot processes of the glia limitans in 4–13% of cerebral microvessels. After intravenous injection of γ‐interferon, either alone or in combination with tumor necrosis factor, these microglial cell processes expressed classes I and II MHC antigens. Studies in (Lewis × DA)F1‐DA bone marrow chimeras demonstrated that these cell processes belonged to resident microglia. This study suggests that microglial cells may play an important role in antigen recognition at the blood‐brain barrier.
Expression of IGF‐I and insulin receptor genes in the rat central nervous system: A developmental, regional, and cellular analysis
Authors: Baron‐Van Evercooren A. , Olichon‐Berthe C. , Kowalski A. , Visciano G. , Van Obberghen E. 
Published: January 2005

AbstractUsing a solution‐hybridization assay and specific oligonucleotidic probes, we have studied IGF‐I and insulin receptor mRNAs in the rat central nervous system during development. The expression of mRNAs was maximal at embryonic day 15 and 20 for IGF‐I receptors, and at embryonic day 20 and the day of birth for insulin receptors. After birth, the expression of both receptor transcripts decreased and reached minimal levels in the adult. At the time at which these transcripts were maximally expressed (embryonic day 20), the regional analysis indicated that IGF‐I receptor transcripts were widely distributed in the brain. In contrast, insulin receptor transcripts were restricted to certain areas in which they were coexpressed with the IGF‐I receptor transcripts. We next analyzed which cells at embryonic day 20 expressed those receptor transcripts. Late embryonic neurons, astrocytes, and neonatal progenitors of oligodendrocytes synthesized both IGF‐I and insulin receptor mRNAs after a short time in culture. However, astrocytes expressed preferentially IGF‐I receptor transcripts, while young progenitors for oligodendrocytes expressed high levels of insulin receptor transcripts. As a whole, our data indicate that during rat CNS development expression of IGF‐I and insulin receptors appears to be stage‐and cell‐specific. The differences observed between the expression of both receptors might point to a specific, but coordinative role of IGF‐I and insulin and their receptors during that time.
T‐lymphocyte entry into the central nervous system
Authors: Hickey W. F. , Hsu B. L. , Kimura H. 
Published: January 2005

AbstractThe entry of T‐lymphocytes into the parenchyma of the central nervous system is a critical early feature in the pathogenesis of many experimental and spontaneously occurring immune‐mediated illnesses. The physiological mechanisms controlling this entry have not been elucidated. This study reports that T‐cell entry into the rat CNS appears to be primarily dependent upon the activation state of the lymphocytes; T‐lymphoblasts enter the CNS (and all other tissues examined) in an apparently random manner while T cells not in blast phase are excluded. Antigen specificity, MHC compatibility, T‐cell phenotypce and T‐cell receptor gene usage do not appear related to the ability of cells to enter. This study demonstrates that when T‐lymphoblasts are introduced into the circulation they rapidly appear in the CNS tissue. Their concentration in the CNS reaches a peak between 9 and 12 hr, and lymphocytes which have entered, exit within 1 to 2 days. Cells capable of reacting with a CNS antigen remain in the tissue or cyclically reenter to initiate inflammation if they are able to recognize their antigen in the correct MHC context. This observation also appears to pertain to the entry of activated T cells into many other tissues, although their concentrations in these non‐CNS sites was not quantitatied.
Increased expression of pp60c‐src protein‐tyrosine kinase during peripheral nerve regeneration
Authors: Le Beau J. M. , Tedeschi B. , Walter G. 
Published: January 2005

AbstractSince little is known about the intracellular changes that take place in response to Schwann cell‐neuron interactions that occur during neurite outgrowth and myelination, we investigated the expression of protein‐tyrosine kinase, pp60c‐src, nerve regeneration through a silicone tube. Segments of regenerated nerve, extracted at various times following nerve‐transection, showed an induction of in vitro c‐src kinase activity as measured by autophosphorylation of immunoprecipitated pp60c‐src. This activity occurred at 7 days following nerve transaction coincident with the onset of neurite outgrowth in vivo. This kinase activity, which peaked out between 21 and 35 days and decreased thereafter, appeared to be associated with axonal growth and myelination, but not mitogenesis in the tube. Analysis of c‐src proteins levels by Western blot showed a similar expression profile as that of the kinase activity. Qualitatively, the expression of an immunoreactive c‐src band, migrating slightly slower than pp60, was detected in extracts of regenerating nerve segments as well as in the corresponding L4 and L5 dorsal root ganglia. This protein may be the CNS neuronal‐specificform (pp60 + ) of the c‐src protein. In situ hybridization revealed that Schwann cells and sensory and motor neurons associated with the regenerated sciatic nerve were positive for c‐src mRNA during regeneration possibly accounting for the increased src protein expression during regeneration, Since the in creased expression of pp60c‐src in regenerated nerve segments coincides with both axonal sprouting and myelination, our findings suggest that the c‐src protein may play a role in Schwann cell‐neuron interactions which facilitate the occurrence of these events during regeneration. In addition, although pp60 + generally not detectable in the mature PNS, our findings show that this protein may be induced during conditions of PNS differentiation which promote neurite outgrowth.
Effect of Na+, K+‐ATPase modifiers on high‐affinity ouabain binding determined by quantitative autoradiography
Authors: Antonelli M. , Casillas T. , Rodríguez de Lores Arnaiz G. 
Published: January 2005

AbstractThere is growing evidence on the existence of endog enous ouabain‐like factors that modulate Na+, K+‐ATPase activity. In this laboratory, two soluble sub‐fractions (peaks I and II) were previously separated from rat cerebral cortex, which, had opposite effects on Na,+K+ ‐ATPase activity. Peak I stimulated and peak II inhibited the enzyme (Rodríguez de Lores Arnaiz and Antonelli de Gomez de Lima, Neurochem Res 11:933‐947, 1986). The same effects are now re ported for K+‐p‐nitrophenyphosphatase activity. Lo calization of high‐affinityouabain binding in rat brain was done by quantitative atitoradiography us ing amicrocomputer digital imaging system. Peak I did not modify, whereas peak II blocked ouabain binding in areas 3–4 of cerebral cortex, dentate gyrus, stria terminalis, thalamic nuclei, and basal gan glia. Similar results were obtained when ouabain binding was determined in rabbit cerebral cortex and by a conventional filtration assay in nerve ending membranes obtained from rat cerebral cortex. These results favour the idea that the factor present in peak II fraction might behave as an ouabain‐like substance.