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  • 1980-1984  (5)
  • 1970-1974  (1)
  • 1965-1969  (3)
  • Polymer and Materials Science  (5)
  • Mouse teratoma  (3)
  • Allopurinol  (1)
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    A prospective study of the development of hypertension and renal stone disease in subjects with increased blood urate (1983)
    Springer
    Urological research 11 (1983), S. 211-213 
    Details
    ISSN: 1434-0879
    Keywords: Allopurinol ; Blood pressure ; Renal stones ; Hyperuricaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The results of a prospective study of the development of hypertension and renal stone disease in subjects with increased blood urate are reported and compared with matched controls. None of the 14 patients on Allopurinol developed a renal stone but one untreated control did. For male patients there was a significant difference (p〈0.01) in diastolic blood pressure between the 2 groups over the 5-year study period, with treated patients having higher blood pressures than untreated controls. This suggests that Allopurinol has had no effect on lowering diastolic blood pressure. Long-term therapy with Allopurinol was effective in reducing mean blood urate levels. It is suggested that blood urate levels are more relevant in predicting renal stone formation and of less value in assessing the therapy and prognosis in hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272281
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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
    Temperature dependence of secondary crystallization in linear polyethylene (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 659-666 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A specimen of linear polyethylene was subjected to isothermal secondary crystallization at a series of temperatures below the primary isothermal crystallization temperature, the melting and primary crystallization stages being held constant throughout the investigation. Dilatometric measurements exhibit an S-character at low values of undercooling Tp - Ts, where Tp and Ts are, respectively, the primary and secondary crystallization temperatures; at larger undercoolings, however, an initial very rapid crystallization is followed by a very slow stage. When corrected for thermal contraction of the polymer, the net degree of secondary transformation is seen to peak at a temperature in the range 109-113°C. The S-character of the isotherms and the peaked temperature variation of degree of transformation lead to the conclusion that a large portion of the secondary crystallization consists of the nucleation and growth of the new crystallites. Johnson-Mehl-Avrami analysis leads to a model of heterogeneous nucleation within the remaining amorphous zones, followed by one-dimensional, diffusion-controlled growth.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.160070405
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of thermal history on fusion curves of polyethylene (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2325-2330 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of thermal history on the melting behavior of several linear polymer and copolymers of ethylene has been studied by using a Perkin-Elmer DSC-1 differential scanning calorimeter. Samples of film were heated above their melting point and then cooled at various rates in order to establish a known thermal history. During melting, homopolymers showed one peak and the copolymers two peaks in the DSC scan. The positions and relative sizes of the peaks were dependent on the prior cooling rate. It is suggested that two crystal types occur in the case of copolymers because of entanglements in the branched segments of the molecules. The position of the lower melting endotherm in blown films suggests that cooling rates of about 500°C./min. are achieved in this process.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1967.070111119
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of proccessing on flow properties of some linear polyethylene resins (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 547-555 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Changes in flow properties of polyethylene resins have often been observed during processing operations. Studies in this laboratory show that melt viscosity of polyethylene normally increases when the resin is heated in a compression mold at temperatures below 300°C. At the same time, the solution viscosity actually decreases in some cases. During extrusion, on the other hand, both melt viscosity and solution viscosity are shown to decrease. In addition, the logarithm of melt flow rate is seen to deviate markedly from the expected linear dependence on reciprocal of absolute temperature. The results suggest that both crosslinking and chain-scission reactions occur during processing, the former predominating at low or zero shear, the latter at high shear.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1968.070120313
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of sulfur-cured styrene-butadiene copolymer rubbers and their polybutadiene blends (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 14 (1970), S. 1-9 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dissolution of sulfur-cured, carbon black-loaded copolymers and their blends with cis-1,4-polybutadiene (PBD) are brought about by boiling with o-dichlorobenzene which contains a small amount of 2,2′-dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high-speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD microstructures permit nominal identification of the kinds of styrene-butadiene rubber and the amounts of cis-1,4-PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis-1,4-PBD, 6.65μ for bound styrene, 10.35 μ for trans-1,4-PBD; and 11.0 μ for vinyl-1,2-PBD. Efforts are being made to improve the data by using a grafting infrared instrument and also to extend the calibrations to include other rubber blends.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1970.070140101
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  • 9
    Electronic Resource
    Electronic Resource
    Copolymerization of liquid sulfur with certain olefinic systems and structure-property studies on the polymeric materialsAbstracted in part from a dissertation submitted to the Departments of Chemistry and Chemical Engineering, Polytechnic Institute of New York, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Polymer Science and Engineering, 1979. (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 383-406 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Liquid sulfur-olefinic reactions at 140°C forming crosslinked polysulfide polymers have been investigated. A systematic approach to the characterization and some structure-property studies on these new polymeric materials has been presented. The olefinic systems of interest are endo-and exo-dicyclopentadiene and an oligomeric alkenyl polysulfide. Equimolar S8-olefinic system copolymers are amorphous and they show no tendency for sulfur crystallization. A correlation has been drawn between chemical structure and glass transition temperature of the copolymers and terpolymers. Mechanical properties and, in particular, chemical stress relaxation of the crosslinked polysulfide polymers have been investigated.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170180201
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