摘要:

AbstractFour human myelin basic protein (MBP) variants with molecular masses of 21.5, 20.2, 18.5, and 17.3 kilodaltons (kDa) have been identified in the developing human spinal cord and their structures determined through an analysis of cDNA clones of their mRNAs. The 20.2‐kDa MBP mRNA encoded a novel MBP variant, the structure of which has not been reported in any species. Its amino acid sequence was identical with that of the 21.5‐kDa MBP except for a deletion of 11 amino acid residues encoded by exon 5 of the MBP gene. All four human MBP variants were identical except for the insertion or deletion of two peptide fragments corresponding to those encoded by exons 2 and 5 of the MBP gene. In this study, no mature human MBP cDNAs missing exon 6 sequences were identified. This suggests that, unlike the mouse, the four human MBP mRNAs encoding these MBP variants arise by the alternative splicing of only exons 2 and 5 from the primary MBP gene transcript. This indicates that the predominant MBP splicing pathways in human and mouse are different.Immunoblots of human fetal spinal cords (11–21 weeks) indicated that MBP expression turned on abruptly between 14 and 16 weeks. Expression of the 20.2‐kDa MBP variant was most evident at 16 weeks and its relative proportion declined thereafter, suggesting that its expression was developmentally re

ISSN:0360-4012    

DOI:10.1002/jnr.490170402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMonoclonal antibody, 1A9, prepared against bovine white matter, recognizes a proteinaceous, myelin‐specific domain in the CNS that is restricted to the surface of oligodendroglia in primary dissociated cell cultures. The antigen is not detected in the PNS or non‐neural tissues. Antibody binding is abolished by heating, exposure to SDS and delipidation, indicating that a conformationally sensitive epitope is recognized. The antigen is present in tracts of developing white matter in rat cerebellum beginning at 5 days postnatally. In developing cultures of fetal rat brain the period of rapid onset for the phenotypic expression of 1A9 antigen is similar to that of galactocerebroside, corresponding to 2–4 postnatal days of age. The 1A9 antigen is not observed in white matter or cultured oligodendroglia of the hypomyelinating jimpy mutant mouse, but its expression is qualitatively normal in the quaking mutant. The possibility is raised that 1A9 may be the primary target of the jimpy mut

ISSN:0360-4012    

DOI:10.1002/jnr.490170403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractT lymphocyte lines and clones selected from Lewis rats immunized with guinea pig basic protein (GP‐BP) proliferate and acquire the ability to transfer experimental autoimmune encephalomyelitis (EAE) after activation by the 68–88 peptide of GP‐BP in concert with autologous I‐A major histocompatibility antigens. In order to evaluate the amino acid sequence required for activation, encephalitogenic T lymphocytes were stimulated with synthetic peptides representing the 69–89, 69–84, 72–84, and 75–84 sequence of GP‐BP. The three longest peptides, but not the 75–84 peptide, induced encephalitogenic lines and clones to proliferate and to transfer clinical EAE; none of the peptides, however, could activate T cell lines of a different epitope specificity. The 69–89 sequence was the most efficient of the synthetic peptides, inducing optimal stimulation comparable to GP‐BP at 10 μg/ml. The 69–84 and 72–84 sequences induced comparable levels of stimulation at 250 μg/ml, but the 75–84 sequence was not active at any concentration. These results show that the 11 amino acids representing the 72–84 sequence of GP‐BP are sufficient to trigger encephalitogenic T cell activity, and suggest that the 85–89 sequence may stabilize the conformation of the encephalitogenic epitope. The close association observed between proliferation and EAE transfer activities, induced in highly purified T cell populations using synthetic peptides, suggests that these two functional properties of T cells result from a common activation pathway involving

ISSN:0360-4012    

DOI:10.1002/jnr.490170404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe substantia nigra (SN) is one of the earliest targets of the 5‐HT neurons of the raphe nuclei (RN). To test the hypothesis that embryonic 5‐HT and catechol‐amine neurons may influence the differentiation of their target cells or source neurons, we have produced dissociated cell cultures from embryonic day 14 (E14) rat rhombencephalon (containing the serotonergic RN) and mesencephalon (containing the dopaminergic substantia nigra, SN). These cells were grown for 6 days in vitro, either as single cultures (RN or SN) or cocultures (RN + SN). Effects of coculture on the morphological development of neurons immunoreactive (IR) for 5‐HT or tyrosine hydroxylase (TH) were studied by measuring a series of morphological parameters related to size of the cell body and dendritic field, as well as to the complexity of neurites within this field, using computer‐assisted morphometry. Increases in a number of these parameters were found in cocultures compared to single cultures for both types of monoamine neurons, but a greater number of parameters were increased for TH‐IR cells, including size of the cell body. Although this might suggest that there was a greater effect of coculture on the TH‐IR (dopaminergic) cells of the SN than on the 5‐HT‐IR cells of the RN, we must consider the fact that a significant population of TH‐IR cells were present in single RN cultures, which contributed to the total population of TH‐IR cells in cocultures. Indeed, when morphometric parameters for TH‐IR cells in RN and SN single cultures were compared, it was found that TH‐IR cells from the RN were generally larger and more complex than those from the SN. Therefore, an analysis was made of which parameters were significantly increased for TH‐IR cells in cocultures compared to single cultures from both SN and RN. This was the case for two parameters: cell body size and absolute field area, indicating that these increases were probably due to the effects of coculture itself rather than to contamination by the larger and more complex TH‐IR cells from the RN. It is impossible to ascertain, however, whether this effect was on cells from the RN, SN, or both. Coculture effects on 5‐HT‐IR cells were easier to analyze, since no such cells were found in single cultures of SN. Three parameters were consistently increased for 5‐HT‐IR cells in coculture: cumulative length of all segments, segment length density, and absolute field area. This indicates that 5‐HT‐IR cells in coculture had larger dendritic fields that contained a more complex array of neurites than their counterparts in single cultures. In sum, coculture seems to promote the growth of both 5‐HT and TH‐IR neurons, but in different ways and to different degrees. These results suggest that some factor or factors related to growth of these monoamine neurons are altered when the rhombencephalon and mesencephalon are cultured together. The exact nature of this

ISSN:0360-4012    

DOI:10.1002/jnr.490170405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAlthough plasma lipoproteins have been demonstrated to have a major role in regulating cholesterol biosynthesis in extraneural cells, no data concerning such regulation are available for developing brain, when cholesterol synthesis is especially active. Glial primary cultures derived from neonatal rat brain and by morphological and biochemical criteria essentially exclusively composed of astrocytes were utilized to examine such regulation. When the primary cultures, which had been maintained in 10% fetal calf serum, were placed in 10% lipoprotein‐poor serum on day 7 of culture, an induction of sterol synthesis (1.6–2.2‐fold) and of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase‐specific activity (1.5‐2‐fold) resulted after 24 hr. Addition of low‐density lipopro‐tein (LDL) to the 10% lipoprotein‐poor serum prevented the induction of both sterol synthesis and HMG‐CoA reductase. However, addition of high‐den‐sity lipoprotein (HDL) to the 10% lipoprotein‐poor serum caused a 1.5–2‐fold further induction of sterol synthesis relative to that in cultures containing 10% lipoprotein‐poor serum alone. In contrast to the glial primary cultures, cultures of C‐6 glioma cells responded to replacement of 10% fetal calf serum with 10% lipoprotein‐poor serum with much more marked increases of sterol synthesis and HMG‐CoA reductase. Although, as with the primary cultures, addition of LDL to the C‐6 glioma cell cultures prevented the increases in sterol synthesis and reductase activity, addition of HDL had no effect. Thus, these results indicate that in developing glial cells in primary culture, cholesterol synthesis and HMG‐CoA reductase are capable of responsiveness to both LDL and HDL. Moreover, at least in terms of regulation of sterol synthesis, C‐6 glioma cells and developin

ISSN:0360-4012    

DOI:10.1002/jnr.490170406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe mammalian neurofilament is made of three neu‐ron‐specific proteins with approximate molecular weights of 70 kilodaltons (kDa) (NF 70K), 150 kDa (NF 15OK), and 200 kDa (NF 200K) by SDS‐PAGE. As previously reported in the rat by Strocchi et al (J Neurochem39:1132–1141,1982) and Nixon et al (J Cell Biol) 94:150–58, 19821, NF 150K comprises three molecular weight variants with the same isoelectric point. A fourth lower molecular weight and slightly less acidic variant was identified by monoclonal and polyclonal antibodies reacting with the a‐helical middle domain of NF 150K. With few exceptions, this lower molecular weight variant did not stain with monoclonal antibodies reacting with the peripheral carboxyterminal domain. Staining with these antibodies was abolished or markedly reduced following neurofilament dephosphorylation. The distribution of the NF 150K variants varied in different regions of the nervous system. The higher molecular weight variant (componenta) was less prominent in brain compared to spinal cord, optic nerve, and sciatic nerve. Further‐more, the lower molecular weight variant (componentd) was not identified in optic nerve and sciatic nerve. All four variants were identified in brain and spinal cord extracts of newborn rats with monoclonal and polyclonal antibodies reacting with the a‐helical middle domain of NF 150K. As a general rule (see Results for exceptions) monoclonal antibodies reacting with the carboxy‐terminal region of NF 150K did not stain the variants in newborn rat brain extracts until day 10 when immunoreactivity of component a first appeared. The adult pattern was first observed on postnatal day 15. With the same antibodies component a was already stained at birth in spinal cord extracts while the adult pattern first appeared on day 10. The delayed appearance of immunoreactivity of the NF 150K variants in development suggests the occurrence of post‐translational modifications probably related t

ISSN:0360-4012    

DOI:10.1002/jnr.490170407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractStudies from our laboratory have shown that classical clinical and histological signs of experimental allergic encephalomyelitis (EAE) may be induced in Lewis rats by synthetic peptides S49 or S55. Peptides S49S and S55S are defined by residues 69–84 and 72–84 of the guinea pig myelin basic protein (MBP), respectively. Peptide S53 (residues 75–84 of the guinea pig MBP), six residues shorter than S49S at the N‐terminal end, induced mild clinical signs of disease unaccompanied by hind leg paralysis, incontinence, or central nervous system pathology. In contrast, peptide S67 (residues 69–81 of the guinea pig MBP), three residues shorter than S49S at the C‐terminal end, did not induce either clinical or histological signs of EAE despite the fact that the S67‐sequence houses an epitope known to induce cell‐mediated immunity. Peptides S49S, S55S, and S53 are antigenic and gave rise to antibodies that recognized either of the three peptide sequences. In this report we explore the interrelationship between cellular immunity induced by the S67 sequence and humoral immunity, induced by the S53 sequence and the development of classical clinical and histological signs of EAE. The results show that the nonencephalitogenic sequence of S67 may be rendered encephalitogenic in the presence of antibody directed against the S53 sequence. Lewis rats immunized with S53 developed pathological signs of EAE only after they were challenged with S67. The fact that a simultaneous challenge with S67 and S53 was as effective in inducing EAE pathology as a delayed one (up to 40 days) suggests that the cellular response to S67 is dependent upon the humoral response to S53. The response to both peptides injected into separate sites mimics the response to the encephalitogenic S49S within which the S67 and the S53 sequences are subsumed. Clearly, a causal relationship is established between the humoral and cellular immunities in inducing EAE. This conclusion is supported by the results of the transfer experiments which showed that either anti‐S53 antibodies or S53‐primed lymphocytes may substitute for S53‐priming in potentiating the development of S67‐induced cell‐mediated immunity an

ISSN:0360-4012    

DOI:10.1002/jnr.490170408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractBrainstem pieces from the trigeminal region of the metencephalic basal plate of 10‐day chick embryos were dissociated and cultured in control conditions or in the presence of muscle‐conditioned medium (MCM). The MCM was derived from age‐matched target tissue relevant to this neuronal region (jaw musculature), from relevant target tissue of an age at which innervation would initially be taking place (4 days), and from nonrelevant target tissue also of an early stage (4‐day limb bud). Neuronal survival and differentiation was assessed daily, for 7 days. Survival and differentiation were significantly enhanced by the 4‐day jaw MCM compared to both the controls and the cultures grown with 10‐day jaw MCM and 4‐day limb MCM. These measures in the presence of 10‐day jaw MCM and 4‐day limb MCM did not differ, but surpassed that seen in control cultures. The results are compared to the more specific responsiveness seen in earlier (2‐day) neural tube cultures, and their relationship to in vivo regenerative nerve fiber outg

ISSN:0360-4012    

DOI:10.1002/jnr.490170409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractFourteen‐day gestation fetal cerebral cortex homografts were transplanted into the thoracic (T6) spinal cord between the left dorsal column and dorsal horn of adult host rats. The transplants were soaked in 2.0 pg/ml of the lectin Phaseolus vulgaris leucoagglutinin (PHAL) prior to implantation. Transplanted host spinal cords were utilized at 7, 14, and 24 d and at 1 and 2 months postimplantation. Paraffin‐sectioned spinal cords were double labeled for PHAL and glial fibrillary acidic protein (GFAP) by using FITC‐ and RITC‐conjugated secondary antisera, respectively. Montages of FITC‐ and RITC‐positive cells were analyzed for cells containing both fluorescences. Double‐labeled cells (PHAL‐GFAP) were transplant‐derived astrocytes. Transplant‐derived astrocytes were observed to initiate migration in the white matter columns of the host at approximately 14 d after transplantation. Double‐labeled astrocytes were observed in cervical and lumbar spinal cord of the host (ca. 3.5 cm away from the center of the transplant) at 2 months postoperative. These astrocytes migrated at approximately 0.76 mm a day (after a 14‐d delay). At 2 months, transplant‐derived astrocytes composed as much as 50% of the astrocytes in the white matter of the host 2.0 mm from the transplant. The migrated astrocytes were hypertrophied and appeared reactive. Astrocytes in spinal gray matter only migrate about 1.0 mm from the graft‐host interface. Transplant‐derived astrocytes can migrate the entire length of

ISSN:0360-4012    

DOI:10.1002/jnr.490170410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractPostsurgical injections of GM1 gangliosides (30 mg/kg IP) reduced neither behavioral deficits in rats following bilateral ablation of the visual cortex nor the extent of retrograde degeneration of neurons in the dorsolateral geniculate nucleus that typically accompanies large lesions of the visual cortex. Our findings are in contrast to previous research, in which ganglioside treatments have been shown to enhance the rate of functional recovery after lesions in other parts of the central nervous system. The negative findings in the present experiment may be due to the disruption of normal circadian rhythms caused by occipital cortex injury.

ISSN:0360-4012    

DOI:10.1002/jnr.490170411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY