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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The biochemical properties of cyclic nucleotide phosphodiesterases in a nonmetastasizing and a spontaneously metastasizing rat mammary carcinoma were compared. The phosphooiesterases in both tumors had a pH optimum of around 8.0 and preferentially hydrolysed cyclic purine nucleotides. The rate of hydrolysis of purine nucleotides in the nonmetastasizing tumor was two times higher than in the metastasizing tumor, but the rate of pyrimidine nucleotide hydrolysis was equal in both tumors. Theophylline, caffeine, and D,L-4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro20-1724) inhibited the enzyme activity in both tumors; the percent inhibition was the same by each inhibitor. The cyclic nucleotie phosphodiesterase activity in either tumor was stimulated by Mg++, Mn++, and Co++ and suppressed by Ca++, Zn,++, and Ni++. EDTA inhibited the activity below the basal level (activity in the absence of added cation), an this inhibition could be recovered up to the basal level by an equimolar quantity of either Mn++ or Mg++. Further stimulation of the enzyme activity with increasing concentrations of divalent cations was observed only with Mn++. Similar effects were observe with ethylene glycol bis(beta-aminoethyl ether)-tn,n-tetraacetic acid. The stimulatory cations affected both the low and high Michaelis constant (tkm) enzymes in these tumors by increasing the maximum velocity. In the low Km enzyme, the Km was also slightly increased. Neither guanosine 3',5'-cyclic monophosphate nor adenosine 3',5'-cyclic monophosphate had any effect on the hydrolysis of the other at physiologic levels.
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PMID:Biochemical properties of cyclic nucleotide phosphodiesterase in metastasizing and nonmetastasizing rat mammary carcinomas. 0 60

Two hydrophilic polymers, dextran and polyethylene glycol, were found to enhance in vitro MLR-type reactions which are weak or nonexistent in normal culture media. BALB/c and C57BL/6 thymocytes were cultured for 4 days in Eagle's MEM + 10% FCS, with or without the x-irradiated lymphomas LSTRA AND EL-4, respectively. By thymidine incorporation no stimulation was observed with EL-4 in plain culture whereas occasionally a very small stimulation was observed with LSTRA. Four percent dextran (w/v, m.w. greater than or equal to 40,000) improves stimulation (E/C) by about 2-fold. The effect of polyethyleneglycol m.w. 6,000 (PEG-6) is much more pronounced. At the optimal concentration of 4 to 5%, PEG-6 causes an increase of 5- to 20-fold in the stimulation index. The PEG-6 effect can also be observed microscopically by the appearance of numerous blasts clustered around the tumour cells. PEG-6 by itself has little effect on thymocytes in the absence of tumor cells. In the case of one-way allogeneic MLR under suboptimal ratios, dextrans (m.w. greater than or equal to 40,000) enhance the reaction dramatically. We speculate that these effects are occurring via a change in the solvent (such as solvent exclusion) in a way which enhances immunologic interactions under conditions which are tolerable to cells in vitro.
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PMID:Enhancement of weak mixed lymphocyte-type reactions by hydrophilic polymers. 6 71

A human glioblastoma multiforme (M27) tested in early cell cultures by indirect immunofluorescence staining showed SV40-related tumor (T)-antigen, 95% of the cells being positive. SV40-related viral capsid (V)-antigen was absent in all cells tested. Experiments to rescue this virus were performed by fusing M27 cells with CV-I monkey cells, which were permissive for SV40, using polyethylene glycol (PEG) as fusion factor. We succeeded in isolating virus particles SV40-GBM which electron microscopy showed to correspond in size and morphology to papovaviruses. Serological tests (hemagglutination, neutralization, fluorescent antibody) revealed that the virus is indistinguishable from SV40. Despite this apparent antigenic identity SV40-GBM differs slightly from SV40 wild type. This virus can propagate and produce CPE in both CV-I cells and primary fetal human kidney cells. Furthermore digestion of SV40-GBM DNA with the HindII/III restriction endonucleases revealed minor differences compared with the SV40 DNA. Therefore the virus SV40-GBM obtained from glioblastoma cells seems to be closely related to the SV40-PML viruses described earlier.
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PMID:Isolation of a SV40-like Papovavirus from a human glioblastoma. 9 81

A new procedure for the fractionation of mucopolysaccharides based upon differences in their partition behavior in aqueous polymer two-phase systems has been devised. Systems containing dextran, poly(ethylene glycol), trimethylamino-poly(ethylene glycol), potassium bromide and sodium phosphate buffer were employed. Countercurrent distributions were performed with a miniature countercurrent distribution device designed especially for use with aqueous polymer two-phase systems. An advantage over the widely used procedures involving precipitation of mucopolysaccharides as their quaternary ammonium detergent complexes is that the countercurrent distribution pattern of a particular mucopolysaccharide is not affected by the simultaneous presence of other mucopolysaccharides. Preliminary distributions of labelled mucopolysaccharides isolated from the cells and culture medium of monolayer cultures of rat tumor cells demonstrate that the procedure is particularly well suited for the fractionation of very minute quantities of mucopolysaccharides.
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PMID:Fractionation of mucopolysaccharides by countercurrent distribution in aqueous polymer two-phase systems. 12 1

During the first two years with the 160 X 160 matrix EMI scanner at Rigshospitalet, Copenhagen 108 consecutive patients referred with the suspicion of intra- or juxtasellar tumor were subjected to 166 computed tomography (CT) examinations. The X-ray attenuation and contrast enhancement patterns of the various lesions were analyzed. In general, it was difficult to correlate these parameters with the histopathological features. Arachnoid cysts, however, had typical low preinjection attenuation and no contrast enhancement. Chromophobe and eosinophilic pituitary adenomas rarely contained calcium and only in minute amounts, hardly visible on the polaroid pictures. Craniopharyngiomas and low grade suprasellar gliomas frequently contained large calcifications. Grade I gliomas, when located in the optic nerves or hypothalamus, showed significantly higher contrast enhancement than elsewhere in the brain. Three purely intrasellar adenomas were demonstrated with CT only. The diagnostic accuracy of CT was compared to that of carotid angiography, PEG and plain skull films in the lesions verified by initial operation (n = 32). CT gave the highest accuracy of the four methods, but the accuracy of CT differed statistically only from that of carotid angiography.
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PMID:Computed tomography of intra- and juxtasellar lesions. A radiological study of 108 cases. 19 49

In this communication we report that fusion of viral and cellular membranes by polyethylene glycol is a convenient approach to overcoming genetically determined resistance to infection. Using this method, avian sarcoma virus-transformed mammalian cells have been produced which serve as useful model systems for the study of Rous sarcoma virus-specific tumor antigens.
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PMID:Polyethylene glycol-mediated infection with avian sarcoma viruses. 21 91

The Ca2+ content of glial tumor (C6) cells was reduced approximately 5-fold by repeated treatment with media containing ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA) without loss of cellular viability. The ability of the cells to accumulate cAMP in response to beta-adrenergic agonists was reduced 60 to 70% following Ca2+ depletion. Ca2+ did not affect the apparent KACT for norepinephrine, nor did it change the concentration of propranolol required to produce 50% inhibition of the maximal norepinephrine response. Phentolamine did not alter the Ca2+ dependence of the response. The binding of dihydroalprenolol by intact C6 cells was not influenced by Ca2+. Furthermore, pretreatment with norepinephrine did not affect the Ca2+ dependence of cAMP accumulation. The effects of Ca2+, therefore, appeared to be exerted on components of the adenylate cyclase system other than the catecholamine receptor. Micromolar free Ca2+ concentration in the extracellular medium were sufficient to restore a maximal norepinephrine response to Ca2+-depeleted cells. The effect of Ca2+ on cAMP accumulation in response to hormone was immediate and was rapidly reversible upon the addition of EGTA in excess of the cation. Cells in media containing Ca2+ exhibited a characteristic biphasic time course of cAMP accumulation; with Ca2+-depleted cells cAMP was accumulated more slowly and the subsequent decline in cAMP content was also reduced. Verapamil, an inhibitor of plasmalemmal Ca2+ influx, decreased the Ca2+-dependent component of the cAMP accumulation when added prior to the cation. The effect of Ca2+ on cAMP accumulation was reduced more extensively by pretreatment of cells at 45 degrees C under Ca2+-depleted (80% loss) than under Ca2+-restored (30% loss) conditions. Trifluoperazine at micromolar concentrations decreased the Ca2+-dependent increment in accumulation of cAMP in Ca2+-restored cells. This inhibition was not overcome by increasing concentrations of norepinephrine or of extracellular Ca2+.
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PMID:Calcium dependence of hormone-stimulated cAMP accumulation in intact glial tumor cells. 22 32

This study describes the generation of permanent T cell tissue culture lines by cell fusion techniques. The AKR strain-derived T cell tumor BW 5147 was hybridized in the presence of polyethylene glycol with various T cell populations isolated from antigen-sensitized mice. Surface analysis of resulting hybrid cell lines showed expression of both Thy-1.2 and H-2 antigens which are characteristic for the lymphocyte used for fusion. In contrast, in hybrids derived from spleen cells neither expression of Ig nor of B cell-typicyl Ia determinants was found suggesting either preferential hybridization of BW 5147 cells with T lymphocytes or extinction of B cell markers in hybrid cells. These hybrid lines which may display the immunological properties of the T cell population chosen are presently investigated for their antigen reactivity.
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PMID:T lymphocyte tissue culture lines produced by cell hybridization. 30 2

A review is presented of 34 cerebellopontine angle tumors surgically removed between 1973 and 1978 by the author at the New York University Medical Center. A diagnostic protocol is outlined: An acoustic PEG (small volume pneumoencephalogram with polytomography) is utilized where a medium to large tumor is suspected, and a Pantopaque fossagram for the smaller tumors. Indications are given for the middle fossa, translabyrinthine and suboccipital approaches, depending on tumor size and level of hearing. Hearing was successfully preserved at or near the preoperative level in 3 of 6 extracanalicular tumors operated upon using the suboccipital microsurgical approach. Audiometric data are given, demonstrating the preservation of hearing. The surgical technique is described. There were no fatalities in the entire series. The incidence of permanent facial nerve palsy was 8%. Nerve palsy occurred in large tumors only.
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PMID:Acoustic neuroma surgery with emphasis on preservation of hearing. 44 34

A congenital dermal sinus at the midline of the parietal region, which extends into the falx, is relatively rare. The following case is illustrative. A 3-year-old girl was noticed by her parents to have tumor at the midline of the parietal region without other disturbances and complaints. This girl had the normal mental and motor development, and was admitted to our clinic for cosmetic surgery. A round, elastic soft tumor, roughly 1x1x1 cm in diameter, was located at the midline of the parietal region. This tumor had a port wine cutaneous discoloration and an absence of normal hair growth in this area. Abnormal hair did not protrude from the sinus. This tumor had no dimple nor sinus opening. Skull XP showed a round lucent bone defect at the midline of the parietal region. This bone defect with sclerotic margin, was about 1 cm in diameter. Skull XP and tomography, with contrast medium injection into the tumor, showed that this tumor extended into the falx through bone defect. Angiography showed that there were no relations between the tumor and the superior sagittal sinus. PEG showed that there were no mass lesion nor dilatation of ventricles. Both spinal tap and EEG were normal. Operation for the congenital dermal sinus was performed on Nov. 4, 1977. This congenital dermal sinus extended into the falx and congenital cell rest tumor was not elicited.
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PMID:[A case of congenital dermal sinus in the parietal region (author's transl)]. 47 Nov 73


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