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  • 1
    Electronic Resource
    Electronic Resource
    Neural differentiation in the OTT-6050 mouse teratoma: Enzymatic and immunofluorescence characterization of a tumor fraction showing melanogenesis in neuroepithelial cells (1981)
    Springer
    Virchows Archiv 393 (1981), S. 27-37 
    Details
    ISSN: 1432-2307
    Keywords: Melanin ; Teratoma ; Tyrosinase ; Tyrosine hydroxylase ; Immunofluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A pigmented tumor fraction, designated IB-9, obtained following cellular dissociation and elutriation procedures applied to the solid transplants of the OTT-6050 mouse teratoma cell line, was characterized enzymatically and by immunofluorescence for the presence of tyrosinase and tyrosine hydroxylase (TH). Enzymatic assays of the pigmented tumors were compared with those obtained on non-pigmented teratoma-derived tumors, on pigmented tumors obtained from the mouse melanoma B16 line as a control for tyrosinase activity, and on whole brains of adult 129/J mice as a control for TH activity. All the teratoma-derived tumors, including the IB-9 fraction, showed a predominance of TH over tyrosinase activity. The levels of TH activity appeared independent of the presence or the extent of melanin pigment. All pigmented teratoma-derived tumors showed low levels of tyrosinase activity. On the basis of the enzymatic assays, the IB-9 tumors were divided into two groups: group I, which showed low enzyme activity, almost certainly entirely tyrosinase; and group II, in which the enzyme activity appeared largely due to TH, with presumably a very low background of tyrosinase activity. Immunofluorescence demonstrated the localization of TH activity to non-pigmented cells of the IB-9 fraction, whereas the pigmented cells showed absence of TH activity. These findings, taken in conjunction with the presence by electron microscopy of premelanosomes and melanosomes, indicate that pigment formation associated with melanosomal differentiation in the neural cells of IB-9 with the histologic patterns of primitive CNS neuroepithelium results from tyrosinase activity only and is therefore unrelated to the metabolic pathways involved in catecholamine synthesis and degradation. It is suggested that, at this stage of differentiation and in this system, the expression of catecholamine synthesis via tyrosine hydroxylase in neuroepithelial cells, and of melanin pigment via tyrosinase, are probably mutually exclusive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430868
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  • 2
    Electronic Resource
    Electronic Resource
    Neural differentiation in the OTT-6050 mouse teratoma: Effects of intracerebral environment on the neural differentiation of embryoid bodies (1981)
    Springer
    Virchows Archiv 393 (1981), S. 39-52 
    Details
    ISSN: 1432-2307
    Keywords: Mouse teratoma ; Embryoid bodies ; Cerebral transplantion ; Neural differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Small embryoid bodies (EB's) from the OTT-6050 transplantable mouse teratoma, obtained by gravity filtration through a 74 μ mesh, were injected into the right cerebral hemisphere of syngeneic newborn or adult mice of both sexes in order to produce differentiating teratomas after a single passage. In subsequent experiments, two solid tumors resulting from two different EB-implants into the brains of adult hosts were used to initiate sequential tumors and were carried intracerebrally in adult mice for 12 and 18 passages respectively. The animals were sacrificed when signs of increased intracranial pressure developed. Survival times were as follows: single passages in adult mice: mean, 35 days; single passages in neonatal mice: mean, 19 days; sequential passages in adult mice: mean, 25 days. Multipotential stem cells accounted for l/2 to 3/4 of the cens in all tumors. Primitive neural cells, ependymoblastic rosettes, neuroblasts and glia were present in all; stem cells, primitive neural cells and rosettes decreased proportionately as the more differentiated neural populations became prominent. Mature ganglion cells were found only in the sequentially passaged tumors and in tumors maintained for more than one month after a single passage in adult mice. Synapses were noted in the most differentiated areas. Neuroblasts were infrequent in tumors developing in neonatal hosts, and mature ganglion cells were absent. Glial fibrillary acidic protein was present by the 24th day in tumors obtained in adult hosts after single passage and in sequential passages. Both in the OTT-6050-derived tumor fractions IB-9 and IB-21, previously reported, and in the EB-derived tumors described in the present study the cerebral microenvironment did not appear to have unique properties favoring neural differentiation and maturation, since similar neural features were found in their subcutaneous counterparts. The findings reported suggest that any accentuation of neuroepithelial differentiation elicited by injecting EB's either intracerebrally or subcutaneously is apparently directly related to the total time of in vivo maintenance of the tumor and therefore presumably to the length of time necessary for such maturation to occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430869
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  • 3
    Electronic Resource
    Electronic Resource
    Neural differentiation in the OTT-6050 mouse teratoma (1981)
    Springer
    Virchows Archiv 392 (1981), S. 281-294 
    Details
    ISSN: 1432-2307
    Keywords: Mouse teratoma ; Centrifugal elutriation ; Neuroepithelial enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dissociation and centrifugal elutriation procedures were applied to subcutaneous transplants of the OTT-6050 mouse teratoma line in order to enrich the neuroepithelial cells. One of the resultant cell fractions, designated IB-21, was then implanted beneath the renal capsule of syngeneic mice and rebanked every 3 to 6 weeks for a total of 58 passages over 5 years. Sequential passages resulted in a tumor restricted to stem cells and neural cells (neuroblasts and glial cells). The primitive neural cells lost the ability to form rosettes after the early transplants. Subcutaneous or intracerebral transplantation of these tumors evinced their capacity for further neuroepithelial differentiation, with the demonstration of astrocytes and occasional mature synapse-forming neurons. Conversion of the tumor to the ascitic form resulted in unorganized clusters of neoplastic cells in contrast to the highly structured embryoid bodies that are characteristic of the parent OTT-6050 line. The absence of non-neural cells in the IB-21 tumor fraction and its ability to demonstrate divergent neural differentiation suggest that a transplantable neural-determined cell population exists in the OTT-6050 mouse teratoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02155666
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  • 4
    Electronic Resource
    Electronic Resource
    Neural differentiation in the OTT-6050 mouse teratoma (1981)
    Springer
    Virchows Archiv 392 (1981), S. 295-308 
    Details
    ISSN: 1432-2307
    Keywords: Mouse teratoma ; Centrifugal elutriation ; Melanotic neuroepithelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dissociation and elutriation procedures were applied to the OTT-6050 mouse teratoma line carried in subcutaneous implants in 129/J mice in order to enrich the differentiating neuroepithelial cells. Subsequent renal subcapsular implantation of one of the resultant cell fractions (IB-9) in syngeneic mice led to the constant production of macroscopically pigmented tumors which, in addition to undifferentiated stem cells, contained primitive neuroepithelial populations composed of medullary epithelium, neuroblasts, and numerous ependymoblastic rosettes. Melanin pigment, confirmed by the presence of melanosomes and premelanosomes, was found in medullary epithelium and other primitive neural cells. The tumors preserved their characteristics through 65 sequential transplants over a period of 5 1/3 years. The pigment was maintained in vitro for up to 3 months in an organ culture system. Subcutaneous or intracerebral transplantation of the renal tumors of the IB-9 fraction accentuated the capacity of these primitive cells towards further neuroepithelial differentiation into mature synapse-forming neurons, and was associated with a decrease in primitive neuroepithelium and an absence or a marked decrease of melanin. Return of the tumor to the kidney resulted in the reappearance of melanin after one to three passages, again associated with the presence of primitive neuroepithelium. The recognition of melanin pigment in the OTT-6050 mouse teratoma transplants could be a useful marker for the successful selection of primitive neuroepithelial cell populations in this experimental tumor system. These populations may help to study the relationship between melanin production and certain types of primitive neuroectodermal tumors in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02155667
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  • 5
    Electronic Resource
    Electronic Resource
    Plasminogen carbohydrate side chains in receptor binding and enzyme activation: A study of C6 glioma cells and primary cultures of rat hepatocytes (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 43 (1990), S. 213-227 
    Details
    ISSN: 0730-2312
    Keywords: tissue-plasminogen activator ; α2-antiplasmin ; protein glycosylation ; miniplasminogen ; streptokinase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The human [Glu1]-plasminogen carbohydrate isozymes, plasminogen type I (Pg 1) and plasminogen type II (Pg 2), were separated by chromatography and studied in cell binding experiments at 4°C with primary cultures of rat hepatocytes and rat C6 glioma cells. In both cell systems, Pg 1 and Pg 2 bound to an equivalent number of receptors, apparently representing the same population of surface molecules The affinity for Pg 2 was slightly higher. With hepatocytes, the KD for Pg 1 was 3.2 ± 0.2 μM, and the KD for Pg 2 was 1.9 ± 0.1 μM, as determined from Scatchard transformations of the binding isotherms. The Bmax was approximately the same for both isozymes. With C6 cells, the KD for Pg 1 was 2.2 ± 0.1 μM vs. 1.5 ± 0.2 μM for Pg 2. Again, the Bmax was similar with both isozymes. 125I-Pg 1 and 125I -Pg 2 were displaced from specific binding sites by either nonradiolabeled isozyme. The KI for Pg 2 was slightly lower than the KI for Pg 1 with hepatocytes (0.9 vs. 1.3 μM) and with C6 cells (0.6 vs. 1.1 μM). No displacement was detected with miniplasminogen at concentrations up to 5.0 μM. Activation of Pg 1 and Pg 2 by recombinant two-chain tissue-plasminogen activator (rt-PA) was enhanced by hepatocyte cultures. The enhancing effect was greater with Pg 2. Hepatocyte cultures did not affect the activation of miniplasminogen by rt-PA or the activation of plasminogen by streptokinase. Unlike the hepatocytes, C6 cells did not enhance the activation of plasminogen by rt-PA or streptokinase; however, plasmin generated in the presence of C6 cells reacted less readily with α2 -antiplasmin.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240430303
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