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  • 1
    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
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  • 2
    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
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  • 3
    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
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  • 4
    ISSN: 1434-0879
    Keywords: Collagen vicryl composite ; Partial nephrectomy ; Urinary tract repair ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A composite membrane produced from collagen and vicryl mesh has been used to cover the kidney surface following partial nephrectomy in rabbits. The membrane readily held sutures, gave satisfactory haemostasis, and prevented leakage of urine. The experiments showed that the prosthesis biodegraded in less than twenty weeks. The only observed long-term effect of the material was thickening of the renal capsule. The results indicate that this membrane may be a suitable reparative materal for use in traumatised kidneys in humans.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-0879
    Keywords: Bladder ; Urinary tract repair ; Collagen/vicryl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Collagen/vicryl (Polyglactin) composite membrane has been used to repair full-thickness defects in the urinary bladder of rabbits. The material has been shown to be biodegradable, prevent leakage of urine, and is readily replaced by collagenous scar tissue lined with a urothelium. Regeneration of smooth nuscle has been observed in the repair area of some animals. The results suggest that such a material may well be of use to urologists wishing to augment contracted bladders or in the repair of bladder fistulae in human subjects, thereby avoiding the use of bowel or other material e.g. omentum.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-0879
    Keywords: Collagen vicryl composite ; Urinary tract repair ; Sutures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A Vicryl (Polyglactin)/Collagen composite membrane has been developed for potential use in urinary tract surgery. The compatability of this membrane, together with its two individual components, collagen film and vicryl mesh, has been tested over a three week period in urine obtained from both healthy and from stone forming patients. The rate of degradation as indicated by changes in the mechanical strength was determined at regular intervals. In addition,absorbable suture materials such as plain catgut, chromic catgut, and vicryl were similarly tested; in the latter case, the breaking stress, and actual loss of weight of the material were compared. The whole series of experiments were then repeated in urine obtained from rabbits, the animal chosen for any future in vivo studies.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-0879
    Keywords: Collage vicryl composite ; Urinary tract repair ; Urinary calculi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Collagen coated vicryl mesh has been incubated with a series of urine collections from healthy and stoneforming patients. For comparison, collagen film, vicryl mesh, and a number of absorbable and non-absorbable sutures were similarly tested. Incubation in rabbit urine were also included in the study. Deposition of urinary salts, estimated qualitatively by electron microcopy, were observed on the collagen vicryl composite in approximately two thirds of the urines tested including rabbit urine. Those urines from patients with a high calcium excretion in particular caused urinary deposits on the material. Similar results were obtained with collagen film although the latter was not tested in rabbit urine. Considerably less deposits of urinary constituents were found with other absorbable materials such as vicryl mesh, vicryl sutures, and chromic catgut, whereas a higher proportion of concretions were found with the nonabsorbable sutures. The results indicate that urinary salt deposition may be a problem associated with collagen based composite materials after prolonged exposure to urine. It must, however, be emphasised that great care should be exercised when extrapolating any results obtained in-vitro to the in-vivo situation.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-0879
    Keywords: Collagen Vicryl composite ; Urinary tract repair ; Urinary tract infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A Collagen/Vicryl (Polyglactin) composite membrane (developed for use in urinary tract surgery) has been incubated in cultures of radioactively labelled urinary tract pathogens vis Escherichia coli, Staphylococcus epidermidis, and Proteus mirabilis for up to 1h. For comparison, collagen film, Vicryl mesh, and a number of absorbable and nonabsorbable sutures were similarly tested. Following incubation, samples were also examined by scanning electron microscopy. Under the experimental conditions employed, only minimal adherence of the micro-organisms to the collagen coated Vicryl mesh, its two individual components, as well as Vicryl and nylon sutures was observed. Significantly greater numbers of bacteria, however, ahered to silk and Chromic Catgut. The results suggest that adherence of microorganisms to the prosthesis even in infected urine is unlikely to develop into a microcolony of bacteria. However, it should be emphasised that great care must be excercised when extrapolating from the in-vitro to the in-vivo situation.
    Type of Medium: Electronic Resource
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