bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Relaxation Properties of bis(5‐Hydroxypenthyl)Phthalate ‐ the Model Oligoester to Study the Relaxation Properties of Polyesters
Authors: Sułkowski Wiesław W. , Maślanka Sławomir , Pentak Danuta , Wolińska Agnieszka , Janeczek Henryk , Paluch Marian , Sułkowska Anna 
Published: February 2007

AbstractThe description of polymer relaxation proprieties is the way to characterize the influence of polymer structure on its useful proprieties of stability and resistance. To perform physicochemical profiles of polymers the synthesis and investigation of model compounds was required. The instrumental methods such as NMR, FTIR, dielectric spectroscopy were used. The results of the experiments allowed us to improve the technology of the synthesis processes and the extension of the range of their usage. Moreover the obtained polymers were more stable and more resistant to degradation. To acquire the profile of the relaxation properties of the linear, hyperbranched and dendrite unsaturated polyester resins, the synthesis of the oligoesters as the model compounds was performed. Pentane‐1,5‐diol phthalic anhydride was used as substrate of the process. The structures of the obtained model compound were confirmed by elemental analysis and 1H NMR and FTIR spectroscopy. Measurements of the relaxation processes of the model compound were also done. The determination of the α, β and β′ relaxation processes for model oligoesters allow us to describe the practical properties of commercial compounds.The description of model relation of the relaxation process may facilitate the interpretation of the dependence between useful properties of polyesters and their molecular structure.
Modification Reactions of Methylhydrosiloxanes with Tricyclodecadiene
Authors: Mukbaniani O. , Zaikov G. , Tatrishvili T. , Mukbaniani N. , Koberidze Kh. 
Published: February 2007

AbstractThe reaction of hydride polyaddition of methylhydridesiloxane and methylhydridesiloxane‐dimethylsiloxane oligomers to unsaturated carbocyclic compound ‐ tricyclodecadiene, at the various ratio of initial compounds, in the presence of platinum hydrochloric acid has been investigated. It was shown that hydrosilylation reaction proceeds both to 1.2 and 9.10 positions and by intermolecular with formation of branching systems. The polyorganosiloxanes with tricyclodecenyl fragment in the side chain, completely soluble in organic solvents were synthesized. For fully characterization of hydride addition of methylhydridesiloxane to tricyclodecadiene, by quantum‐chemical half empiric AM1 method, for all initial, intermediate and final products, in modelling reaction of hydrosilylation of methyldimethoxysilane to tricyclodecadiene, the heats of formations (ΔHf), change of energy (ΔH) of the system depending on the change of distance (RC‐Si) between C‐Si bonds, also the charges values (q) on the atoms, dipole moments (µ) and bonds orders (Pij) are calculated. It was concluded, that the course of hydride addition of modelling reaction of methyldimethoxysilane to tricyclodecadiene energetically is more favourable by 9.10‐addition. The hydride polyaddition reaction order, activation energies and rate constants were found. The synthesized oligomers were characterized by 1H and 13C NMR, FTIR, thermogravimetry, gel permeation chromatography, differential scanning calorimetry and wide angle X‐ray methods.
Expression pattern of a gene for a secreted metalloproteinase during late stages of tumor progression
Authors: Ostrowski Lawrence E. , Finch Joanne , Krieg Peter , Matrisian Lynn , Patskan George , O'connell John F. , Phillips James , Slaga Thomas J. , Breathnach Richard , Bowden G. Tim 
Published: February 2007

AbstractWe have reported that transin RNA, a 1.9‐kb RNA coding for a novel, secreted proteinase, was overexpressed during the progression of benign mouse skin papillomas to malignant squamous cell carcinomas (SCCs) induced by a two‐stage protocol (Proc Natl Acad Sci USA 83:9413, 1986). Recently a high degree of similarity has been demonstrated between rabbit stromelysin, a secreted metalloproteinase that degrades proteoglycans found in the basement membrane and the amino acid sequence predicted in rat transin cDNA.DNA sequencing of a mouse cDNA isolated from an SCC (initiated by 7,12‐dimethylbenz[a]anthracene [DMBA] and promoted by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPAJ) showed greater than 85% nucleotide similarity and 90% amino acid similarity to the rat transin‐1 cDNA nucleotide and predicted amino acid sequences. Using this mouse transin cDNA clone as a probe (labeled with 32P) we found enhanced levels of transin mRNA transcripts in SCCs induced by a protocol giving rise to metastatic tumors (repeated N‐methyl‐N‐nitroso‐N'‐nitroguanidine [MNNG] treatments) compared with the level found in SCCs induced by a protocol that had a lower probability of giving rise to metastatic tumors (MNNG initiation followed by TPA promotion). A study of primary SCCs and metastatic lesions induced by repeated benzo[a]pyrene treatment showed that the levels of transin mRNA transcripts were reduced in the metastatic lesions in comparison to the primary tumors. Southern analysis of the DNA isolated from epidermis, papillomas, and SCCs indicated that neither transin gene amplification nor rearrangement accounted for increased levels of the transin mRNA transcripts. These data suggest a role for enhanced levels of transin production in the invasion and metastasis of chemically induced SCCs.
The chemical carcinogen, chloroacetaldehyde, modifies a specific site within the regulatory sequence of human cytomegalovirus major immediate early gene in vivo
Authors: Kohwi‐Shigematsu Terumi , Nelson Jay A. 
Published: February 2007

AbstractThe reaction of chemical carcinogens with DNA is well documented, but whether this interaction occurs at specific sites in chromatin is unknown. We have examined in vivo the reaction of a known carcinogen, chloroacetaldehyde, with the active and inactive major immediate early gene of human cytomegalovirus. We found that during active transcription of the gene, this chemical carcinogen reacts with a unique DNA site in the 5′ flanking sequence of the major immediate early gene. However, no reaction was detected in infected nonpermissive cells in which the gene was inactive. The chloroacetaldehyde‐reactive site is located at ‐836 pmn 10 bp from the mRNA cap site in the part of the regulatory region that can both negatively and positively affect promoter activity [Nelson et al., Mol Cell Biol 7:4125–4129, 1987]. These results suggest, at least in the case of chloroacetaldehyde, the possibility that the molecular mechanism of chemical carcinogenesis involves a chemical reaction at specific sites in chromatin within the sequences responsible for regulation of gene expression. Such carcinogen‐DNA interaction occurs as a consequence of a non‐B DNA structure that contains unpaired DNA bases existing at specific sites in chromatin.
In vitro and in vivo regulation of liver epithelial cells carrying a metallothionein‐rasT24 fusion gene
Authors: Seyama Toshio , Godwin Andrew K. , Dipietro Margaret , Winokur Thomas S. , Lebovitz Russell M. , Lieberman Michael W. 
Published: February 2007

AbstractWe inserted a zinc‐responsive metallothionein‐rasT24 fusion gene in both orientations into a retroviral vector (SVX) and infected Fisher rat liver epithelial cells. Only the construction in which the viral long terminal repeat and the metallothionein promoters were in opposite orientations resulted in cell lines with biologically altered behavior. Two lines (MTR‐1 and MTR‐6) showed altered morphology in vitro when ZnSO4 was added to the medium. These cell lines grew in soft agarose in a dose‐dependent manner. Immunoprecipitation experiments revealed dose‐dependent increases in the rate of synthesis of the mutant p21Ha‐ras protein in these lines in response to ZnSO4. Both lines produced poorly differentiated metastatic adenocarcinomas when injected subcutaneously in Fisher rats, and tumors derived from MTR‐6 cells grew more rapidly in animals on a zinc‐supplemented diet than on a zinc‐deficient diet. Uninfected liver epithelial cells showed no change in morphology in vitro after ZnSO4 addition and did not grow in soft agarose or after subcutaneous transplantation during the 14‐wk experimental period. These results indicate that altered levels of expression of a single gene (rasT24) can have profound effects on the biologic behavior of tumor cells both in vitro and in vivo.
Characterization of DNA‐protein complexes induced in intact cells by the carcinogen chromate
Authors: A. Charles Miller , Costa Max 
Published: February 2007

AbstractPotassium chromate induced the formation of DNA‐protein complexes in cultured Chinese hamster ovary cells. The DNA‐protein complexes were isolated by ultracentrifugal sedimentation in the presence of 2% sodium dodecyl sulfate (SDS) and 5 M urea. Two‐dimensional SDS‐polyacrylamide gel electrophoresis analysis of the chromate‐induced DNA‐protein complexes revealed that two acidic proteins of 53 and 45 kDa and a basic protein of 54 kDa were selectively complexed to the DNA. Numerous other proteins also became associated with the DNA to a lesser degree as the chromate concentration was increased. Nuclease digestion was not a prerequisite for the resolution of the protein component of the DNA‐protein complexes using two‐dimensional gel electrophoresis. Ultracentrifugal analysis of the DNA‐protein complexes in the presence of proteinase K, nucleases, or a chelating agent demonstrated that protein aggregation was not responsible for the increased protein recovery in chromate‐treated samples and that the complexes were disrupted by EDTA. These data suggest that the selectively complexed proteins were associated with the DNA through strong interactions that may be mediated by the trivalent form of chromium.
Differences between normal and transformed murine fibroblasts in the expression of various promoter/enhancer—chloramphenicol acetyltransferase constructs
Authors: Begemann Martin , Hsiao W.‐L. Wendy , Weinstein I. Bernard 
Published: February 2007

AbstractHigh levels of poly(A)+ RNAs homologous to certain endogenous retrovirus‐related DNA sequences are frequently seen in carcinogen‐transformed rodent cells. To explore the underlying mechanism, transient expression assays were done to determine whether carcinogen‐ or radiation‐transformed C3H 10T1/2 cell lines differ from normal 10T1/2 cells in terms of their ability to express the chloramphenicol acetyltransferase (CAT) gene when it is linked to various promoter/enhancer sequences, including two independently isolated intracisternal A particle (IAP) long terminal repeat sequences designated prcm and pMIA6. We found that with several constructs, CAT activity was always 3‐ to 10‐fold higher in the transformed 10T1/2 cell lines than in the normal 10T1/2 cells. The prcm‐CAT construct displayed the highest CAT activity in both the normal and transformed C3H 10T1/2 cells. Studies with 32P‐labeled prcm‐CAT DNA and Southern blot analyses indicated that the differences in CAT activity between normal and transformed cells were not due to greater uptake or retention of the transfected DNA by the transformed cells. Competition studies provided evidence that factors required for the expression of the prcm‐CAT construct are present in limited amounts in normal 10T1/2 cells and in excess amounts in transformed 1011/2 cells. These putative factors may play a role in the increased expression of endogenous retrovirus‐related sequences in the transformed cells.
Molecular cloning of mouse epidermal cystatin A and detection of regulated expression in differentiation and tumorigenesis
Authors: Hawley‐Nelson Pamela , Roop Dennis R. , Cheng Christina K. , Krieg Thomas M. , Yuspa Stuart H. 
Published: February 2007

AbstractA Xgt 11 cDNA expression library representing mouse epidermis mRNA was screened with polyclonal rabbit antiserum directed against 10–13 kDa epidermal antigens that had previously been shown to be regulated during epidermal differentiation. A cDNA clone was detected and isolated and its identity as the coding sequence for one of the antigens was confirmed by translation of hybrid‐selected mRNA from mouse epidermis. The cDNA sequence predicted a peptide homologous to the reported sequence of rat epidermis cystatin A, a thiol proteinase inhibitor. This identification was confirmed by cross‐reactivity of the μgm clone fusion protein with authentic antiserum to rat epidermis cystatin A. Southern gel analysis showed that mouse DNA may contain several closely related genes homologous to the cystatin probe. An mRNA of about 0.6 kb from epidermis and cultured mouse epidermal cells hybridized with the cystatin probe on northern analysis. The abundance of the message was high in cultured basal cells and was selectively diminished by inducing terminal differentiation in culture with an elevated Ca2+ concentration in the medium. Cystatin message was abundant in chemically induced mouse skin papillomas but reduced in carcinomas. In epidermis, mRNA was localized to the less differentiated basal and lower spinous layers by in situ hybridization. Regulation of expression of cystatin A in epidermis and tumors suggests that it may be important in the control of normal keratinocyte proliferation and differentiation and in malignant conversion.
Mutagen activation by cDNA‐expressed P1450, P3450, and P450a
Authors: Aoyama Toshifumi , Gonzalez Frank J. , Gelboin Harry V. 
Published: February 2007

AbstractcDNAs for rodent P1450, P3450, and P450a were expressed in the modified vaccinia virus‐T7 RNA polymerase system. Each P450 exhibited its appropriate molecular weight and characteristic enzyme activity. Aryl hydrocarbon hydroxylase activity was catalyzed by P1450, acetanilide hydroxylase by P3450, and testosterone 7a‐hydroxylase by P450a. Ethoxycoumarin deethylase was exhibited by both P1450 and P3450. Each expressed P450 was also analyzed for its ability to activate 19 carcinogens of diverse classes to their mutagenic forms. Most notable was the activation of several polycyclic aromatic hydrocarbons by P1 and the activation of acetylaminofluorene, 4‐aminobiphenyl, and several heterocyclic amine food pyrolysate products by P3450. P450a, in contrast, showed slight mutagen activation only toward N‐hydroxy‐2‐acetyl aminofluorene. The vaccinia virus‐T7 RNA polymerase system described here can express cDNAs for diverse forms of P450, each of which can then be characterized for substrate and product specificity and for mutagen activation.
Transformation of an established mouse mammary epithelial cell line following transfection with a human transforming growth factor alpha cDNA
Authors: Shankar Vidya , Ciardiello Fortunato , Kim Nancy , Derynck Rik , Liscia Daniel S. , Merlo Giorgio , Langton Beatrice C. , Sheer Donald , Callahan Robert , Bassin Robert H. , Lippman Marc E. , Hynes Nancy , Salomon David S. 
Published: February 2007

AbstractTo determine whether the enhanced expression of transforming growth factor α (TGFα) is sufficient to induce the neoplastic transformation of an immortalized population of mammary epithelial cells, we cotransfected NOG‐8 cells, a cloned mouse mammary epithelial cell line, with a simian virus 40‐human TGFα cDNA expression vector plasmid and a pSV2neo plasmid. After cotransfection, nine G418‐resistant NOG‐8 colonies were cloned and expanded. All clones were subsequently analyzed for TGFα mRNA expression by northern blot analysis, TGFα secretion, anchorage‐dependent growth in serum‐free medium, anchorage‐independent growth in soft agar, and tumorigenicity in nude mice. Three TGFα‐transfected NOG‐8 clones expressed high levels of a specific TGFα mRNA, secreted elevated levels of TGFα into the culture medium (177–595 ng/108 cells/48h), exhibited an enhanced growth rate, grew aggressively as colonies in soft agar, and formed undifferentiated, invasive carcinomas in nude mice. A neutralizing mouse monoclonal antibody generated against the low molecular weight human TGFα peptide was able to inhibit colony formation in soft agar by TGFα‐transfected NOG‐8 clones that produced high levels by TGFα This inhibition suggested that TGFα acted through an external autocrine loop. NOG‐8 cells and NOG‐8 cells transfected with a pSV2neo plasmid alone secreted very low levels of TGFα, failed to grow as colonies in soft agar and did not form tumors in nude mice. These results demonstrate that overexpression of a human TGFα cDNA in immortalized, nontransformed mouse mammary epithelial cells can induce a transformed phenotype in vitro and can facilitate tumor formation in vivo.
Molecular analysis of DNA isolated from the different stages of X‐ray‐lnduced transformation in vitro
Authors: Krolewski Bozena , Little John B. 
Published: February 2007

AbstractA major challenge in radiation carcinogenesis is to identify the cellular gene or genes involved in initiating the process. We examined the transforming activities of DNAs obtained from C3H10T1/2 cells during x‐ray‐induced morphological transformation. DNAs extracted from mass cultures of 10T1/2 cells at different times after irradiation with 600 rad and from type III‐transformed foci were transfected into NIH 3T3 cells. The results indicate that certain oncogenes are activated beginning 3 wk after irradiation, well before the appearance of macroscopically visible transformed foci. For DNA isolated from x‐ray‐transformed 10T1/2 cells (type III foci), the frequencies of transfection were 0.003–0.11 foci/μg of genomic DNA with NIH 3T3 cells and 0.004–0.04 foci/μg genomic DNA using 10T1/2 cells as recipients. Southern blot analysis of DNAs obtained from 23 primary transfectants and from 23 x‐ray‐transformed cell lines indicated no gross rearrangements or amplification of any of the 14 oncogenes screened (v‐Ha‐ras, v‐Ki‐ras, N‐ras, v‐myc, v‐raf, v‐src, v‐fes, v‐abl, v‐mos, v‐erbA, v‐erbB, M‐myb, v‐fos, v‐sis). This suggests that x‐irradiation may activate as yet unidentified oncogenes. The occurrence of positive transfection 3 wk after irradiation is discussed in terms of the hypothesis that transformation may not occur as a direct consequence of the exposure to x‐rays but develops as a rare event in the progeny of the irradiated cells at some later time, as a consequence of the delayed activation of certain genes.
Intracellular receptor binding and nuclear transport of nerve growth factor in intact cells and a cell‐free system
Authors: Rakowicz‐Szukzynska Ewa M. , Linnenbach Alban J. , Koprowski Hilary 
Published: February 2007

AbstractNuclear uptake of125I‐labeled nerve growth factor (NGF) by cells that either express or do not express the cell surface receptor was tested using intact cells and a cell‐free system. Intracellular and consequently nuclear uptake of NGF in intact cells was dependent on the presence of surface NGF receptor, whereas nuclear uptake in a cell‐free system did not correlate with cell surface receptor expression. In the cell‐free system, nuclear transport was inhibited when NGF receptor was being actively synthesized. Preincubation of intact cells with unlabeled NGF, cycloheximide, puromycin, or actinomycin D increased nuclear uptake up to threefold. The data suggest that, in intact cells, NGF transported into the cell via the surface receptors is also bound by the NGF receptor being synthesized in the cytoplasm. NGF taken up by the nucleus inhibited transcription of ribosomal RNA genes by 70% and, in turn, inhibited cell proliferation by 60%. A direct effect of NGF on transcription is discussed.
Effects of various chemical agents on the transformation of rat fibroblasts by an activated c‐Ha‐ras oncogene
Authors: Lopez Cecilia A. , Hsiao W.‐L. Wendy , Weinstein I. Bernard 
Published: February 2007

AbstractWe have previously reported that the potent tumor‐promoting agent 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) and a factor from fetal calf serum (FCS) markedly enhance the transformation of mouse C3H 10T1/2 and Rat 6 fibroblasts, when added to cultures following transfection with plasmid pT24 DNA that contains an activated c‐Ha‐ras oncogene. In the present study, we examined possible enhancing or inhibiting effects of various chemicals on the transformation of Rat 6 fitbroblasts by T24 DNA when tested in the presence of calf serum, calf serum plus TPA or FCS. We found that, like TPA, the chemicals mezerein, 1‐oleoyl‐2‐acetylglycerol, and phospholipase C increased the yield of T24‐induced foci, thus further implicating protein kinase C as a critical constituent in this process. Low concentrations (10−6–10−7M) of retinoic acid (both trans and 13‐cis) also stimulated cell transformation. Several compounds inhibited T24‐induced transformation. These included nontoxic concentrations of the calcium ionophore A23187, indomethacin, and ϵ‐amino‐n‐caproic acid. Compounds that failed to exert a significant reproducible effect included vasopressin, vitamin D3, selenium, antipain, Bowman‐Birk inhibitor, vitamin B12, epidermal growth factor, platelet‐derived growth factor, insulin, and transferrin. These findings suggest that this simple in vitro system might be useful for detecting enhancers and inhibitors of ras oncogene‐induced cell transformation and also elucidating their mechanisms of action.
Mutational specificities of environmental carcinogens in the lacl gene of Escherichia coli. II: A host‐mediated approach to N‐nitroso‐N, N‐dimethylamine and endogenous mutagenesis in vivo
Authors: Horsfall Michael J. , Zeilmaker Marco J. , Mohn Georges R. , Glickman Barry W. 
Published: February 2007

AbstractAn intrasanguineous host‐mediated assay was used to determine the mutational specificity of the hepato‐carinogen N‐nitroso‐N, N‐dimethylamine metabolized in vivo. A total of 114 forward mutations in the lacl gene of Escherichia coli reisolated from the livers of treated Swiss albino mice were characterized at the DNA sequence level. Consistent with the methylating ability of this compound and the demonstrated mutagenic specificity of O6‐methylguanine, the predominant mutation was the G:C→A:T transition. These were recovered, on average, seven times more frequently at guanines flanked (5′) by a purine residue than at those preceded by a pyrimidine residue—a specificity similar to that reported for many direct‐acting SN1 alkylating agents. This nitrosamine appears to be distinguished from related N‐nitroso methylating compounds by the induction of additional mutational events. Here, the exceptions consisted of four A:T→G:C transitions, four A:T site transversions, and a single G:C→T:A transversion. In addition, the DNA sequence alterations of 34 I− mutants of E. coli reisolated from otherwise untreated mice were identified. The predominant mutation was the G:C→A:T transition, which accounted for almost half of all background mutations. The sites at which these mutations were recovered appear to indicate that some of these mutations may have arisen as a result of an accelerated rate of cytosine deamination. These data suggest that many of the additional “spontaneous” mutations observed under in vivo conditions resulted from genotoxic events occurring during the host‐defense (immune) reaction.
Cellular oncogene expression in cell lines derived from tumors produced by transformed rat tracheal epithelial cells
Authors: Walker Cheryl , Nettesheim Paul 
Published: February 2007

AbstractFive tumor‐derived cell lines established from transformed rat tracheal epithelial (RTE) cells were examined for activated oncogenes using the NIH 3T3 assay, and the expression of 11 cellular oncogenes in the transformed cells was quantitated and compared with expression in normal RTE cells. DNA from the tumor‐derived cell lines lacked transforming activity, but expression of several oncogenes (fos, abl, Ki‐ras, Ha‐ras, and p53) was higher in the transformed cells than in normal RTE cells.