bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vitamin D analogues in the treatment of psoriasis
Authors: Kragballe Knud 
Published: May 2005

AbstractPsoriasis is a chronic hyperproliferative skin disease in which inflammatory and immunologic processes may play important pathophysiologic roles. Recently the skin has been identified as a target tissue for vitamin D. Because 1,25‐dihydroxy vitamin D3 inhibits epidermal proliferation and promotes epidermal differentiation, it has been introduced for the treatment of psoriasis vulgaris. In addition to 1,25‐(OH)2‐D3, synthetic vitamin D3 analogues have undergone clinical evaluation. Calcipotriol (INN) (calcipotriene [USAN]) has been studied most extensively. Compared with 1,25‐(OH)2‐D3, calcipotriol is about 200 times less potent in its effects on calcium metabolism, although similar in receptor affinity. Topical calcipotriol 50 μg/g applied twice daily is efficacious and safe for the treatment of psoriasis. Because topical calcipotriol is slightly more efficacious than betamethasone 17‐valerate and dithranol, calcipotriol should be considered a first line drug in the management of psoriasis. These results illustrate that it is possible to separate the vitamin D effects on the cellular level from those on calcium metabolism not only in vitro, but also in a clinical setting.
Oncogene expression in mammary epithelial cells
Authors: Groner Bernd 
Published: May 2005

AbstractMouse strains which develop tumors at a high incidence with characteristics very similar to human cancers have been derived over the last 8 years. The tumors are caused by defined genetic alterations in the mouse genome. Three areas of research have contributed to the derivation of these mouse strains: (1) Molecular analysis of human tumors has shown that distinct oncogenes and tumor suppressor genes are consistently involved in a high percentage of primary tumors. (2) Regulatory enhancer‐promoter sequences have been identified which direct gene expression to specific target cells, preferentially mammary epithelial cells. (3) The introduction of recombinant DNA molecules into fertilized mouse eggs by microinjection and integration of the injected DNA into the genome of injected cells has given rise to mutant mouse strains with unique and defined genetic alterations. Studies with different promoter‐oncogene combinations introduced into transgenic mouse strains have led to the following general conclusions: (1) Oncogenes expressed in mammary gland cells predispose transgenic mice to mammary tumors. (2) The oncogenic potential of indivdiual oncogenes in mammary epithelial cells differs. (3) Oncogene expression initially often causes a preneoplastic state affecting growth and differentiation parameters of cells. (4) The expression of different oncogenes synergizes to reduce tumor latency. Synergism can also be observed with physiological growth signals like estrogen or growth hormone. The oncogenes with a role in mammary carcinomas which have been investigated in transgenic mice will be described here. The phenotypic consequences of oncogene expression and the implications for the multistep carcinogenesis model will be discussed.
Differential induction of heme oxygenase in the hepatocarcinoma cell line (Hep3B) by environmental agents
Authors: Lutton J. D. , da Silva J.‐L. , Moqattash S. , Brown A. C. , Levere R. D. , Abraham N. G. 
Published: May 2005

AbstractIn situ hybridization and Northern analysis of heme oxygenase (HO) mRNA was used to determine the induction and expression of HO by various environmental agents. Exposure of Hep3B cells to hemin (10 μM) for as little as 5 min resulted in significant production of HO transcripts and mRNA expression as seen by in situ hybridization. We followed the pattern of HO transcript accumulation by heme and results indicate that the peak of induction of HO by heme was reached between 10 and 20 minutes. Other metalloporphyrins were all effective in inducing HO mRNA after 1 h exposure. On the other hand, CoCl2 caused accumulation of HO mRNA at a later time than seen with the metalloporphyrins. However, lipopolysaccharide (LPS) gave a more immediate effect on HO induction which was somewhat similar to heme in its time course. Direct measurements of HO activity revealed that enzyme activity could be detected after about 20 min exposure to hemin, and this activity was inhibited by tin protoporphyrin (SnPP). The different pattern of HO mRNA induction by LPS as contrasted with CoCl2 suggests that LPS may act through a different translational factor, or stimulate free radical formation and the subsequent release of heme and induction of HO. These results indicate that heme causes accumulation of HO mRNA by a different mechanism than that of CoCl2. Finally, LPS shares a concomitant effect on induction of HO as an acute phase reactant type protein.
Disulfide‐linked and noncovalent dimers of p185HER‐2 in human breast carcinoma cells
Authors: Lin Yuzhong J. , Christianson Tracy A. , Clinton Gail M. 
Published: May 2005

AbstractEnhanced levels of disulfide‐linked dimers of the neu oncogene product have been suggested to be associated with the transformed state [Weiner DB, Liu J, Cohen JA, Williams WV, Greene MI: Nature 338 : 230–231, (1989)]. We, therefore, investigated the properties of the dimeric forms of p185HER‐2/neu from the human breast carcinoma cell line, SK‐BR‐3. We found disulfide‐linked dimers as well as noncovalently associated dimers that were detected by cross‐linking with bis(sulfosuccinimidyl) suberate (BS3). However, the disulfide‐linked dimers did not exist in intact cells, since they were eliminated when the cells were lysed in the presence of the alkylating agent, sodium iodoacetate. Moreover, the disulfide‐linked dimeric molecules were not the activated form of p185HER‐2 since they incorporated about the same level of phosphate in an in vitro kinase reaction as the monomeric molecules. In contrast, the noncovalent dimers appeared to be present on the surface of intact cells and were phosphorylated at levels at least tenfold higher than monomers in an in vitro kinase reaction.
Altered DNA/Protein complexes specific for the β‐Interferon regulatory region observed in murine embryonal carcinoma F9 cells
Authors: Francis Mary Kay , Lehman John M. 
Published: May 2005

AbstractMurine embryonal carcinoma (EC) F9 cells do not produce interferon (IFN) at the protein or RNA level in response to inducing agents, while retinoic acid differentiated F9 cells do produce IFN. A probe was constructed spanning positions −104 to −39 of the human β‐IFN upstream regulatory region to examine this developmental control at the level of a transcriptional regulatory mechanism. Gel mobility shift analyses were used to examine this molecular mechanism to determine whether the differential expression of positive or negative trans‐acting factors may act to control β‐IFN expression in undifferentiated EC cells. These analyses showed that while nuclear extracts from poly‐l,C induced L929 cells, in the IFN producing cell line, showed two shifted bands, nuclear extracts from both induced and uninduced F9 cells showed only one shifted band using the −104/ −39 probe. While this single shifted band co‐migrated with the faster migrating species of L929 cell extracts, competition analysis revealed differences between the two complexes. An oligonucleotide representing the positive regulatory domain PRDII competed efficiently for the probe when induced F9 cell extracts were examined, but failed to compete when induced L929 cell extracts were examined. In contrast, an oligonucleotide representing the positive regulatory domain PRDI competed very well when induced L929 cell extracts were examined but had only a minimal effect when induced F9 cell extracts were examined. These data suggest the involvement of developmentally regulated transcriptional factors(s) which have yet to be characterized.
Differential transport and processing of variant mouse mammary tumor virus glycoproteins
Authors: Platt Emily J. , Kain Steven R. , Goodman Laurie J. , Firestone Gary L. 
Published: May 2005

AbstractThe transport and proteolytic processing of two individual gene isolates of the mouse mammary tumor virus (MMTV) glycoprotein were compared in transfected rat HTC hepatoma cells. Plasmids were constructed such that the MMTV glycoprotein genes were constitutively expressed from the promoter within the Rous Sarcoma Virus 5′ Long Terminal Repeat in the absence of other MMTV proteins. An isolate of the GR strain MMTV glycoprotein was efficiently transported and processed resulting in the localization of MMTV glycoproteins at the cell surface and in the extracellular environment. Moreover, the kinetics of acquisition of endoglycosidase H resistant oligosaccharide side chains and the rate of endoproteolytic cleavage of the glycosylated polyprotein expressed in transfected cells were virtually identical to that observed in viral‐infected rat hepatoma cells. In contrast, a natural variant of the C3H strain MMTV glycoprotein expressed in transfected cells was retained in an intracellular compartment by a heavy chain binding protein (Bip)‐independent pathway in an endoglycosidase H sensitive and uncleaved form. This MMTV glycoprotein isolate was retained early in the exocytic pathway and displayed a half‐life of approximately 45 min in transfected cells. Only a minor fraction of the expressed C3H variant glycoprotein was detected at the cell surface but was not externalized. Our results suggest that the variant C3H MMTV glycoprotein contains one or more mutations that preclude its efficient transport through the exocytic pathway.
Glucocorticoid and retinoid regulation of alpha‐2 type I procollagen promoter activity
Authors: Perez Jose R. , Shull Susan , Cutroneo Kenneth R. , Gendimenico Gerard J. , Capetola Robert J. , Mezick James A. 
Published: May 2005

AbstractGlucocorticoids decrease type I procollagen synthesis by decreasing the steady state levels of procollagen mRNAs and mRNA synthesis. The present studies were undertaken to determine the functional sequences of the proα2(1) collagen gene required for the glucocorticoid‐mediated decrease of type I procollagen mRNA synthesis. Embryonic mouse fibroblasts were stably transfected with the pR40 DNA CAT construct containing the 5′ flanking region fragment from −2048 to +54 and the intronic fragment from +418 to +1524 of the mouse α2(I) collagen gene. Dexamethasone treatment of these pR40 transfected fibroblasts resulted in a significant decrease in CAT activity which agrees with the glucocorticoid‐mediated decrease of the steady state levels of type I procollagen mRNAs. To determine the ppossible role of the first intron fragment in the dexamethasone‐mediated decrease of CAT activity, pR36, a CAT plasmid containing the first intron fragment and the SV40 early promoter, was trasnfected into mouse fibroblasts and treated with dexamethasone. No significant decrease in CAT activity was observed. The dexamethasone‐mediated response was then localized within the 5′ flanking region by preparing a series of constructs containing internal deletions and transfecting these plasmids into mouse fibroblasts. The regions −2048 to −981 and −506 to −351 were required for the dexamethasone response of gene activity. However, the DNA stretch from −981 to −506 was not. Analysis of the DNA sequences of these regions revelaed a singel GRE at −1023 to −1018 and a modified doublet at −873 to −856. The doublet GRE contains and A/T strand switch of the third base pair as compared to the single GRE and is not necessary for dexamethasone regulation of gene activity. All‐trans‐retionic acid increased CAT activity of the same pR40 CAT construct transfected in the mouse fibroblasts. DNA sequencing revealed a RARE and a modified RARE in the stretch of DNA from −981 to −506. Deletion of only the latter DNA region eliminated the elevation of CAT activity elicited by all‐trans‐retinoic acid. Our results indicate that the single GRE and the RARE are required for glucocorticoid and retinoic acid regulation of proα2(I) collagen gene activity, respectively.
Replacement of lysine‐181 by aspartic acid in the third transmembrane region of endothelin type B receptor reduces its affinity to endothelin peptides and sarafotoxin 6c without affecting G protein coupling
Authors: Wu Lan‐Hsin , Mauzy Camilla , Egloff Ann Marie , Chung Fu‐Zon , Zhu Guochang , Mirzadegan Taraneh 
Published: May 2005

AbstractA conserved aspartic acid residue in the third transmembrance region of many of the G protein‐coupled receptors has been shown to play a role in ligand binding. In the case of endothelin receptors, however, a lysine residue replaces this conserved aspartic acid residue. To access the importance of this residue in ligand binding, we have replaced it with an aspartic acid in the rat endothelin type B (ETb) receptor by PCR mediated mutagenesis. The binding characteristics and functional properties of both the wild type and mutant receptors were determined in COS‐7 cells transiently expressing the cloned receptor cDNAs. Using 125I‐ET‐I as the radioactive peptide ligend in displacement binding studies, the wild type receptor displayed a typical non‐isopeptide‐selective binding profile with similar IC50 values (0.2–0.6 nM) for all three endothelin peptides (ET‐1, ET‐2, and ET‐3) and sarafotoxin 6c (SRTX 6c). Interestingly, the mutant receptor showed an increase in IC 50 values for ET‐1 (5nM), ET‐2 (27nM), and ET‐3 (127nM) but displayed a much larger increase in 1C50 value for SRTX 6c ( > 10uM). The lysine mutant receptor still elicited full incositol phosphate (IP) turnover responses in the presence of saturating concentrations of endothelins (10nM of ET‐1, 100nM of ET‐2, or 1uM of ET‐3), indicating that the mutation (K181D) did not affect the coupling of mutant receptor to the appropriate G protein. These demonstrate that lysine‐181 on the receptor is important for binding ET peptides; however, it is required for binding the ETb selective agonist‐SRTX5c. © 1992 Wiley‐Liss, Inc.
Phosphorylation of vinculin in human platelets spreading on a solid surface
Authors: Hagmann Jörg , Burger Max M. 
Published: May 2005

AbstractVinculin is a cytoskeletal protein believed to be involved in linking microfilaments to the cell membrane. it is a substrate for the Ca2+ ‐ and phospholipid‐dependent protein kinase C. We show here that when human platelets attach and spread on a solid surface, the α isoforms of vinculin become phosphorylated at serine and/or threonine residues. Phosphorylation is dependent on adhesion to a surface, since suspended, unattached platelets can produce filopodia but no phosphorylation of vinculin. Phosphorylation is also dependent on actin polymerization, as it does not occur when platelets had been pretreated with cytochalasin B. Most likely, protien kinase C is responsible for the phosphorylation of vinculin, since phosphorylation also occurs when platelets are treated with a phorbol ester, which activates protein kinase C, and is blocked by treatment with a staurosporine derivative which inhibits this enzyme. These results suggest that phosphorylation plays a role in anchoring vinculin at sites of microfilament‐membrane interaction. © 1992 Wiley‐Liss, Inc.
Transforming growth factor‐beta1 induces expression of statin during differentiation of human promonocytic leukemia cells
Authors: Lgnotz Ronald A. 
Published: May 2005

AbstractTransforming growth factor‐Beta (TGF‐β) is a potent growth inhibitor for several cell types including epithelial cells and hematopoietic progenitor cells. Using a human promonocytic leukemia cell line, THP‐1, we have shown that TGF‐β inhibits their proliferation and promotes differentiation into cells exhibiting macrophage‐like properties. Therefore, a key question is whether TGF‐β influences the expression of genes associated with proliferation and/or growth inhibition. TGF‐β treatment of THP‐1 cells results in downregulation of expression of c‐myc. We also observe that TGF‐β1‐treated cells express reduced levels of the cell cycle regulated histone, H2B, but express elevated levels of an RNA splicing variant of this histone that has been observed to be upregulated in growth inhibited and terminally differentiated cells. In addition, a nuclear protein associated with senescence and withdrawal of cells from the cell cycle, statin, is also expressed by THP‐1 cells in response to TGF‐β1 ttreatment. These results suggest that TGF‐β1 is capable of inducing expression of specific nuclear proteins associated with differentiation and/or cessation of proliferation that may result in changes in nuclear organization and altered gene expression. Such changes in nuclear organization may be incompatible with continued proliferation of the cells. © 1992 Wiley‐Liss, Inc.
Induction of an immune response through the idiotypic network with monoclonal anti‐idiotype antibodies in the carcinoembryonic antigen system
Authors: de Moraes Jane Z. , Lopes J. Daniel , Carneiro Célia R. W. , Buchegger Franz , Mach Jean‐Pierre 
Published: May 2005

AbstractAnti‐idiotype antibodies can mimic the conformational epitopes of the original antigent and act as antigent substitutes for vaccination and/or serological purposes. To investigate this possibility concerning the tumor marker carcinoembryonic antigent (CEA), BALB/c mice were immunized with the prevously described anti‐CEA monoclonal antibody (MAB) 5.D11 (AB1). After cell fusion, 15 stable cloned cell lines secreting anti‐lds (AB2) were obtained. Selected MAbs gave various degrees of inhibition (up to 100%) of the binding of 125I‐labeled CEA to MAb 5.D11. Abesence of reactivity of anti‐ld MAbs with normal mouse lgG was first demontrated by the fact that anti‐ld MAbs were not absorbed by passage through a mouse lgG column, and second because they bound specifically to non‐reduced MAb 5.D11 on Western blots. Anti‐5.D11 MAbs did not inhibit binding to CEA of MAb10.B9, another anti‐CEA antibody obtained in the same fusion as 5.D11, or that of several anti‐CEA MAbs reported in an international workshop, with the exception of two other anti‐CEA MAbs, bothe directed against the GOLD IV epitope. When applied to an ld‐anti‐ld competitive radioimmunoassay, a sensitivity of 2 ng/ml of CEA was obtained, which is sufficient for monitoring circulating CEA in carcinoma patients. To verify that the anti‐ld MAbs have the potential to be used as CEA vaccines, syngeneic BALB/c mice were immunized with these MAbs (AB2). Sera from immunized mice were demonstrated to contain AB3 antibodies recongnizing the original antigen, CEA, both in enzyme immunoassay and by immunoperoxidase staining of human colon carcinoma. These results open the perspective of vaccination against colorectal carcinoma through the use of anti‐idiotype antibodies as antigen substitutes. © 1992 Wiley‐Liss, Inc.
Glucocorticoids promote development of the osteoblast phenotype by selectively modulating expression of cell growth and differentiation associated genes
Authors: Shalhoub Victoria , Conlon Donna , Stein Gary S. , Lian Jane B. , Tassinari Melissa , Quinn Cheryl , Partridge Nicola 
Published: May 2005

AbstractTo understand the mechanisms by which glucocorticoids promote differentiation of fetal rat calvaria derived osteoblasts to produce bone‐like mineralized nodules in vitro, a panel of osteoblast growth and differentiation related genes that characterize development of the osteoblast phenotype has been quantitated in glucocorticoid‐treated cultures. We compared the mRNA levels of osteoblast expressed genes in control cultures of subcultivated cells where nodule formation is diminished, to cells continuously (35 days) exposed to 10 ‐7 M dexamethasone, a synthetic glucocorticoid, which promotes nodule formation to levels usually the extent observed in primary cultures. Tritiated thymidine labelling revealed a selective inhibition of internodule cell proliferation and promotion of proliferation and differentiation of cells forming bone nodules. Fibronectin, osteopontin, and c‐fos expression were increased in the nodule forming period. Alkaline phosphatase and type I collagen expression were initially inhibited in proliferating cells, then increased after nodule formation to support further growth and mineralization of the nodule. Expression of osteocalcin was 1,000‐fold elevated in glucocorticoid‐differentiated cultures in relation to nodule formation. Collagenase gene expression was also greater than controls (fivefold) with the highest levels observed in mature cultures (day 35). At this time, a rise in collagen and TGFβ was also observed suggesting turnover of the matrix. Short term (48 h) effects of glucocorticoid on histone H4 (reflecting cell proliferation), alkaline phosphatase, osteopontin, and osteocalcin mRNA levels reveal both up or down regulation as a function of the developmental stage of the osteoblast phenotype. A comparison of transcriptional levels of these genes by nuclear run‐on assay to mRNA levels indicates that glucocorticoids exert both transcriptional and post‐transcriptional effects. Further, the presence of glucocorticoids enhances the vitamin D3 effect on gene expression. Those genes which are upregulated by 1,25(OH)2D3 are transcribed at an increased rate by dexamethasone, while those genes which are inhibited by vitamin D3 remain inhibited in the presence of dexamethasone and D3. We propose that the glucocorticoid promote changes in gene expression involved in cell‐cell and cell‐extracellular matrix signaling mechanism that support the growth and differentiation of cells capable of osteoblast phenotype development and bone tissue‐like organization, while inhibiting the growth of cells that cannot progress to the mature osteoblast phenotype in fetal rat calvarial cultures. © 1992 Wiley‐Liss, Inc.
Expression of histone and alkaline phosphatase genes in UMR 106‐01 rat osteoblast‐like cells exposed to the hoechst dye H33342
Authors: Zheng M. H. , Wysocki S. , Papadimitriou J. M. , Wood D. 
Published: May 2005

AbstractThe fluorescent Dye H33342 (H342) is a bis‐benzimidazole used for intravital fluorescent staining. In this report, we found that H342 completely abolished histone 2a mRNA but had no effect on alkaline phosphatase gene expression and protein synthesis in UMR 106‐01 rat osteoblast‐like cells. The complete loss of histone 2a mRNA occurred after only 20 min of treatment with H342. This effect is unlikely to be a result of inhibition of DNA synthesis, which was only partly suppressed. The mechanism of the action of H342 on histone 2a mRNA is presently unknown. © 1993 Wiley‐Liss, Inc.
Effect of retinyl acetate on the assembly of the fibronectin extracellular matrix and the processing of the fibronectin receptor β subunit of confluent C3H/10T1/2 mouse embryo fibroblasts
Authors: Suzuki Satoshi S. , Piette Lawrence H. 
Published: May 2005

AbstractThe mouse embryo fibroblast cell line, C3H/10T1/2, synthesized and deposited a large amount of fibronectin especially in the pericellular matrix. Confluent cultures of these cells cultured in the presence of 0.3 μg/ml of retinyl acetate released cell surface fibronectin and the extracellular matrix fibronectin fibrils were disorganized. The immunoblot analysis demonstrated that the number of the fibronectin receptor was decreased in the prolonged culturing of retinyl acetate‐treated cells. Immunoprecipitation of 35S‐methionine pulse‐chase labeled cell extracts by antifibronectin receptor antibody indicated that about one‐half of the pre‐β subunit was processed and converted to the mature form in control cells, and only about one‐fourth of the pre‐β subunit was processed in the retinyl acetate‐treated confluent cells. 1‐deoxymannojirimycin (MNJ), which is an inhibitor of oligosaccharide processing, induced disorganization of the extracellular matrix fibronectin assembly similar to that observed with retinyl acetate. The results of this study suggest that a mechanism of action of retinyl acetate is inhibition of the glycosylation during processing of the fibronectin receptor, a step necessary for fibronectin binding and for assembly of the extracellular matrix. © 1993 Wiley‐Liss, Inc.