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Biomedical subjects

M Noble

Publications and source records attributed to M Noble.

At least 73 records · Page 4Linked to original sources
PubMed1993

The inhibition of oligodendrocytic differentiation of O-2A progenitors caused by basic fibroblast growth factor is overridden by astrocytes.

The inhibition of differentiation of oligodendrocyte-type-2 astrocyte (O-2A) progenitors into oligodendrocytes caused by basic fibroblast growth factor (bFGF) can be overcome by non-O-2A lineage cells present in the optic nerve and by astrocytes purified from cerebral cortices. Although purified O-2A progenitors grown in the presence of bFGF for up to 6 days were inhibited from differentiating into oligodendrocytes, O-2A progenitors growing in heterogeneous optic nerve cultures did not show a similar inhibition of differentiation. The factor(s) responsible for overriding the inhibitory effects of bFGF appeared to be secreted by astrocytes, as extensive generation of oligodendrocytes was seen in cultures of purified O-2A progenitors exposed to bFGF+ medium conditioned by purified astrocytes (ACM). In addition, purified O-2A progenitors displayed a remarkable sensitivity to bFGF, which extended at least down to concentrations of 0.03 ng/ml, a concentration of < 2 x 10(-12) M. At a bFGF concentration of just 0.1 ng/ml, this mitogen still promoted DNA synthesis in as many O-2A progenitors as in cultures exposed to 1-30 ng/ml of this growth factor, but exhibited a reduced ability to promote DNA synthesis in oligodendrocytes. In addition, although concentrations of bFGF as low as 0.03 ng/ml were a potent stimulator of DNA synthesis in O-2A progenitors, application of this amount of bFGF no longer inhibited the differentiation of progenitors into oligodendrocytes as effectively as application of higher bFGF concentrations. Thus, the induction of DNA synthesis by bFGF can be uncoupled from the inhibition of differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Purification of olfactory nerve ensheathing cells from the olfactory bulb.

Cells of the olfactory nerve layer of the olfactory bulb are labeled with the O4 antibody, which also labels Schwann cells, oligodendrocytes, and many oligodendrocyte-type-2 astrocyte (O-2A) progenitors. Purification of cells which were O4+, but did not express galactocerebroside (GC), from spinal cord, hippocampus, corpus callosum, and cerebellum of perinatal rats always yielded cells with the expected characteristics of O-2A progenitors. In contrast, the great majority of O4+GC- cells isolated from the olfactory bulb expressed an antigenic phenotype and pattern of differentiation in vitro which did not correspond with that of any previously described glial populations. As the localization of O4 staining in the olfactory bulb indicates that these cells are olfactory nerve ensheathing cells (ONECs), our results therefore suggest that ONECs represent a novel glial cell-type which can now be analyzed as a purified population.

Animals↗
PubMed1993

The characterization of astrocyte cell lines that display properties of glial scar tissue.

The glial scar has been proposed to be a major impediment to regeneration in the adult CNS. Analysis of glial scars in vivo is complicated, however, by the large number of cell types present in such lesions. We have attempted to simplify analysis of the glial scar environment by deriving a series of conditionally immortal astrocyte cell lines that display several properties expressed by glial scar tissue in vitro. The astrocyte lines, which were derived from H-2KbtsA58 transgenic mice, expressed macromolecules associated with glial scars in vivo and were significantly less effective than neonatal astrocytes at promoting neurite outgrowth from postnatal central and peripheral neurons. The astrocyte lines also inhibited migration of oligodendrocyte type-2 astrocyte progenitor cells in vitro. We propose that certain properties shown previously to be expressed by glial scars may be reconstituted in vitro by astrocytes alone.

Animals↗
PubMed1993

Single cell analysis of the expression of a nuclear protein, SCIP, by fluorescent immunohistochemistry visualized with confocal microscopy.

A widely applicable method for the accurate quantification or semiquantification of macromolecules at the level of individual cells is described and validated; this is a method which may considerably facilitate the study of many biological processes. This method relies on measuring fluorescent emission in immunocytochemically labelled cells with a confocal microscope. Emission is related quantitatively to the level of the fluorophore by the combination of an analysis of the polarization of the fluorescent emission and fluorophore rationing methods. The method was applied to the study of the expression of the suppressed cyclic AMP-induced POU protein (SCIP) transcription factor in glial cells of the central nervous system. In particular, the method allowed the study of transcription factor expression in defined cells present in heterogeneous cultures and in cell types which cannot be isolated in sufficient numbers for biochemical analysis using conventional techniques.

Animals↗
PubMed1993

Overexpression of Her-2/neu may be an indicator of poor prognosis in prostate cancer.

Previous reports have shown that Her-2/neu oncogene expression in human breast cancer and ovarian cancer may be associated with poorer prognosis. We report the expression of Her-2/neu on fresh samples of known prostatic adenocarcinoma but not on those of benign prostatic hypertrophy. Using a monoclonal antibody (TA1) directed against human Her-2/neu oncogene product and an immunohistochemical staining method, no Her-2/neu expression was noted with benign prostatic hypertrophy (15 samples). With prostatic adenocarcinoma samples, a subset (9 of 25) showed overexpression of Her-2/neu. Such overexpression is correlated with higher histological grade, higher stage of disease, and high S phase and aneuploidy on flow cytometric analysis. These findings suggest that Her-2/neu may be a prognostic marker in prostate cancer as well.

Adenocarcinoma↗
PubMed1993

Profile of prostatic-specific antigen in prostatic carcinomas.

Prostatic carcinomas (PCs) may be divided into two distinct categories: latent PCs, found mostly at autopsy, and clinical cases, which present with signs and symptoms. These two categories correspond fairly well to histologic grading of PCs and immunoperoxidase staining for prostatic specific antigen (PSA). The objective of this study was to find quantitative and qualitative differences if any, of PSA in PCs, corresponding to Gleason's histologic grade. By radiometric assay of PSA in tissue cytosol, PCs especially those of high histologic grade, were found to have lower PSA concentrations than normal and glandular hyperplastic prostatic tissue. Western blotting of cytosol was performed to detect differences between immunoreactive PSA of PCs compared with noncancerous tissue using both polyclonal and monoclonal antibodies against PSA. Western blotting with anti-PSA revealed some different bands between cancerous and noncancerous cytosols. Western blotting of cancerous and noncancerous cytosols was also performed using anti-prostatic acid phosphatase and anti-beta micro-seminoprotein. Reduced PSA concentration and different immunoblotting pattern of PSA were found to be characteristic for PCs, especially in carcinomas with grades higher than 7, which usually present with more aggressive invasion and metastases.

Acid Phosphatase↗
PubMed1993

Proton nuclear magnetic resonance spectroscopy unambiguously identifies different neural cell types.

Proton nuclear magnetic resonance (1H NMR) spectroscopy is a noninvasive technique that can provide information on a wide range of metabolites. Marked abnormalities of 1H NMR brain spectra have been reported in patients with neurological disorders, but their neurochemical implications may be difficult to appreciate because NMR data are obtained from heterogeneous tissue regions composed of several cell populations. The purpose of this study was to examine the 1H NMR profile of major neural cell types. This information may be helpful in understanding the metabolic abnormalities detected by 1H NMR spectroscopy. Extracts of cultured cerebellar granule neurons, cortical astrocytes, oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells, oligodendrocytes, and meningeal cells were analyzed. The purity of the cultured cells was > 95% with all the cell lineages, except for neurons (approximately 90%). Although several constituents (creatine, choline-containing compounds, lactate, acetate, succinate, alanine, glutamate) were ubiquitously detectable with 1H NMR, each cell type had distinctive qualitative and/or quantitative features. Our most unexpected finding was a large amount of N-acetyl-aspartate (NAA) in O-2A progenitors. This compound, consistently detected by 1H NMR in vivo, was previously thought to ne present only in neurons. The finding that meningeal cells have an alanine:creatine ratio three to four times higher than astrocytes, neurons, or oligodendrocytes is in agreement with observations that meningiomas express a higher alanine:creatine ratio than gliomas. The data suggest that each individual cell type has a characteristic metabolic pattern that can be discriminated by 1H NMR, even by looking at only a few metabolites (e.g., NAA, glycine, beta-hydroxybutyrate).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Crystal structure of a Src-homology 3 (SH3) domain.

The Src-homologous SH3 domain is a small domain present in a large number of proteins that are involved in signal transduction, such as the Src protein tyrosine kinase, or in membrane-cytoskeleton interactions, but the function of SH3 is still unknown (reviewed in refs 1-3). Here we report the three-dimensional structure at 1.8 A resolution of the SH3 domain of the cytoskeletal protein spectrin expressed in Escherichia coli. The domain is a compact beta-barrel made of five antiparallel beta-strands. The amino acids that are conserved in the SH3 sequences are located close to each other on one side of the molecule. This surface is rich in aromatic and carboxylic amino acids, and is distal to the region of the molecule where the N and C termini reside and where SH3 inserts into the alpha-spectrin chain. We suggest that a protein ligand binds to this conserved surface of SH3.

Amino Acid Sequence↗
PubMed1992

The differentiation of glial cell progenitor populations following transplantation into non-repairing central nervous system glial lesions in adult animals.

The non-repairing nature of the locally x-irradiated ethidium bromide (EB)-induced demyelinating white matter lesion has been further validated by showing that injections of two cultures which promote host remyelination of EB lesions in normal tissue do not do so in x-irradiated lesions. The behaviour of an oncogene-immortalized glial cell line and a growth-factor-expanded glial progenitor population have been examined following transplantation into the non-repairing EB lesion. Our studies indicate that the selected glial cell populations were each capable of establishing glial environments around demyelinated axons. Extensive oligodendrocyte remyelination with little astrocytic presence was observed in lesions transplanted with growth-factor-expanded optic nerve progenitors, while less extensive oligodendrocyte remyelination with the establishment of astrocyte-like cells was found in lesions transplanted with ts A58-SV40T immortalized glial cells. Prolonged expansion of both populations resulted in a loss of differentiation to normal glial phenotypes.

Animals↗
PubMed1992

Development and regeneration in the O-2A lineage: studies in vitro and in vivo.

This brief review discusses selected aspects of our studies on the control of division and differentiation of the glial precursor cells which give rise to oligodendrocytes. For more extensive reviews on this topic, the reader is referred to recent reviews by Raff (1989), Richardson et al. (1991), Noble (1991) and Noble et al. (1991).

Aging↗
PubMed1992

Adjuvant radiotherapy in high stage transitional cell carcinoma of the renal pelvis and ureter.

This review was undertaken to assess the influence of adjuvant radiation therapy on failure patterns and survival in high stage transitional cell carcinoma of the renal pelvis or ureter. Ninety-four patients with transitional cell carcinoma of the renal pelvis or ureter were retrospectively reviewed. Twenty-six had American Joint Commission stage T3 or T4 N0/+, M0 disease and underwent curative resections (median follow-up 13.5 months, range 3-311). Local failure was defined as recurrence in the tumor bed, regional nodes, or ureteral stump. Time to recurrence and survival were calculated from the time of pathologic diagnosis. Variables associated with local failure, distant metastasis, and survival were analyzed using univariate and multivariate analysis. Seventeen received surgery only, nine received adjuvant radiation therapy (median dose 50 Gy). Local failure occurred in 9 of 17 without and 1 of 9 with adjuvant radiation therapy (p = 0.07). Actuarial 5-year local control was 34% without and 88% with adjuvant radiation therapy. Cox step-wise regression confirmed adjuvant radiation therapy (p = 0.006) and grade (p = 0.006) as significantly associated with local failure. No patients with low grade lesions suffered local failure either with or without adjuvant radiation therapy. High grade lesions had an local failure rate of 15% with and 71% without adjuvant radiation therapy. Metastatic disease occurred in 4 of 9 and 8 of 17 with and without radiation therapy. No significant factors influencing distant failure were identified. Five-year actuarial survival was 44% with and 24% without adjuvant radiation therapy. The survival differences were not statistically significant on univariate or multivariate analysis. High staged transitional cell carcinoma of the renal pelvis or ureter has a substantial local failure risk after surgery alone. Adjuvant radiation therapy markedly reduces this risk but has no impact on distant disease which occurs in approximately 50%. Effective adjuvant therapy will require effective systemic therapy in addition to adjuvant radiation therapy.

Aged↗
PubMed1992

The O-2A(adult) progenitor cell: a glial stem cell of the adult central nervous system.

Systematic comparison of the properties of oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells derived from optic nerves of perinatal and adult rats has revealed that these two populations differ in many fundamental properties. In particular, O-2A(perinatal) progenitor cells are rapidly dividing cells capable of generating large numbers of oligodendrocytes over a relatively short time span. Oligodendrocyte differentiation generally occurs synchronously in all members of a clone, thus leading to elimination of that clone from the pool of dividing cells. However, some O-2A(perinatal) progenitors are also capable of giving rise to O-2A(adult) progenitors. These latter cells express many of the characteristics of stem cells of adult animals, including the capacity to undergo asymmetric division and differentiation. We suggest that precursors which function during early development give rise to terminally differentiated end-stage cells and to a second generation of precursors with properties more appropriate for later developmental stages. It is this second generation of precursors which express the properties of stem cells in adult animals, and we therefore further suggest that our work offers novel insights into the possible developmental origin of stem cells.

Animals↗
PubMed1992

In vitro analysis of the origin and maintenance of O-2Aadult progenitor cells.

We have been studying the differing characteristics of oligodendrocyte-type-2 astrocyte (O-2A) progenitors isolated from optic nerves of perinatal and adult rats. These two cell types display striking differences in their in vitro phenotypes. In addition, the O-2Aperinatal progenitor population appears to have a limited life-span in vivo, while O-2Aadult progenitors appear to be maintained throughout life. O-2Aperinatal progenitors seem to have largely disappeared from the optic nerve by 1 mo after birth, and are not detectable in cultures derived from optic nerves of adult rats. In contrast, O-2Aadult progenitors can first be isolated from optic nerves of 7-d-old rats and are still present in optic nerves of 1-yr-old rats. These observations raise two questions: (a) From what source do O-2Aadult progenitors originate; and (b) how is the O-2Aadult progenitor population maintained in the nerve throughout life? We now provide in vitro evidence indicating that O-2Aadult progenitors are derived directly from a subpopulation of O-2Aperinatal progenitors. We also provide evidence indicating that O-2Aadult progenitors are capable of prolonged self renewal in vitro. In addition, our data suggests that the in vitro generation of oligodendrocytes from O-2Aadult progenitors occurs primarily through asymmetric division and differentiation, in contrast with the self-extinguishing pattern of symmetric division and differentiation displayed by O-2Aperinatal progenitors in vitro. We suggest that O-2Aadult progenitors express at least some properties of stem cells and thus may be able to support the generation of both differentiated progeny cells as well as their own continued replenishment throughout adult life.

Aging↗
PubMed1992

Cooperation between PDGF and FGF converts slowly dividing O-2Aadult progenitor cells to rapidly dividing cells with characteristics of O-2Aperinatal progenitor cells.

We have shown previously that oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells isolated from adult rat optic nerves can be distinguished in vitro from their perinatal counterparts on the basis of their much slower rates of division, differentiation, and migration when grown in the presence of cortical astrocytes or PDGF. This behavior is consistent with in vivo observations that there is only a modest production of oligodendrocytes in the adult CNS. As such a behavior is inconsistent with the likely need for a rapid generation of oligodendrocytes following demyelinating damage to the mature CNS, we have been concerned with identifying in vitro conditions that allow O-2Aadult progenitor cells to generate rapidly large numbers of progeny cells. We now provide evidence that many slowly dividing O-2Aadult progenitor cells can be converted to rapidly dividing cells by exposing adult optic nerve cultures to both PDGF and bFGF. In addition, these O-2Aadult progenitor cells appear to acquire other properties of O-2Aperinatal progenitor cells, such as bipolar morphology and high rate of migration. Although many O-2Aadult progenitor cells in cultures exposed to bFGF alone also divide rapidly, these cells are multipolar and migrate little in vitro. Oligodendrocytic differentiation of O-2Aadult progenitor cells, which express receptors for bFGF in vitro, is almost completely inhibited in cultures exposed to bFGF or bFGF plus PDGF. As bFGF and PDGF appear to be upregulated and/or released after injury to the adult brain, this particular in vitro response of O-2Aadult progenitor cells to PDGF and bFGF may be of importance in the generation of large numbers of new oligodendrocytes in vivo following demyelination.

Animals↗
PubMed1992

The quantification of fluorescent emission from biological samples using analysis of polarization.

The quantification of fluorescent emission from biological specimens can only be carried out in cellular regions where the relationship between fluorophore concentration and fluorescent emission is linear. Using a confocal scanning laser microscope, we show that quantification of fluorescent emission from biological samples labelled with fluorescein and fluorescein analogues mounted in a viscous medium can be readily achieved. Where the distribution of fluorophore is highly localized, for example in cells labelled for immunofluorescence analysis, we demonstrate that analysis of fluorescence depolarization can identify regions in which fluorophore concentration exceeds the range in which the relationship to fluorescent emission is linear. We also demonstrate that, under the conditions examined, depth-dependent effects, fading and quenching are either small enough to be ignored or can be corrected for mathematically when quantifying fluorescent emission.

Animals↗
PubMed1992

Specific expression of N-acetylaspartate in neurons, oligodendrocyte-type-2 astrocyte progenitors, and immature oligodendrocytes in vitro.

To test the specificity of N-acetylaspartate (NAA) as a neuronal marker for proton nuclear magnetic resonance (1H NMR) spectroscopy, purified and characterized cultured cells were analyzed for their NAA content using both 1H NMR and HPLC. Cell types studied included cerebellar granule neurons, type-1 astrocytes, meningeal cells, oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells, and oligodendrocytes. A high concentration of NAA was found in extracts of cerebellar granule neurons (approximately 12 nmol/mg of protein), whereas NAA remained undetectable in purified type-1 astrocytes, meningeal cells, and mature oligodendrocytes. However, twice the neuronal level of NAA was found in O-2A progenitors grown in vitro. In addition significant levels of NAA were also detected in cultures of immature oligodendrocytes. Our data partly support previous suggestions that NAA may be a useful neuronal marker for 1H NMR spectroscopic examination of the adult brain. However, they also raise the further possibility that alterations of NAA associated with some specific brain disorders, particularly disorders seen in newborn and young children, may reflect abnormalities in the development of oligodendroglia or their precursors.

Animals↗
PubMed1992

From chance to choice in the generation of neural cell lines.

Despite the central importance of cell lines in contemporary studies in cellular and molecular biology, many areas of potential investigation remain impeded by the limited number of lines available and by the difficulty in generating new lines of interest. Thus, there has been a constant pressure to develop improved methods for obtaining cell lines of particular interest. This review examines some of the problems associated with in vitro approaches to cell line generation. In addition, two different ways in which transgenic animals can be used to overcome the limitations of in vitro production of cell lines are discussed. In the first approach, specific promoters are utilized to target expression of immortalizing genes to cells of interest. The second approach is concerned with development of a strain of transgenic animals (the H-2KbtsA58 transgenic mouse) designed to obviate the need for identification of cell-type specific promoters, and in which it is theoretically possible to directly generate conditionally immortal cell lines from any tissue of the body by simple dissection and growth of cells in appropriate tissue culture conditions. Finally, approaches are also discussed in which investigations on the control of precursor differentiation have been applied so as to bypass the need for expression of activated immortalizing oncogenes in the generation of large quantities of conditionally immortalized cells with the capacity to undergo normal differentiation in vitro and in vivo.

Animals↗