bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinoids upregulate phagocytosis by human dermal microvascular endothelial cells
Authors: Vora Meena , Karasek Marvin A. 
Published: February 2005

AbstractAnimals fed a diet deficient in vitamin A show severe physiological changes that often result in death. At the cellular level, retinoids have been shown to induce differentiation of cells dervied from a wide spectrum of tissues, including the vasculature. To understand further the mechanisms for these events, we studied the effects of 13‐cis‐retinoic acid, all trans‐retinoic acid, all‐trans‐retinol, and all‐trans‐retinol acetate on human dermal microvascular endothelial cells (HDMEC). Concentrations of retinoids in the physiological range from 0 to 1 μM were used in our experiments. These concentrations were nontoxic to HDMEC. Here we report that in addition to the known effect of retinoids on keratinocytes and sebacytes, retinoids induced morphological and functional changes in HDMEC that gave these cells macrophage like characteristics. 13‐Cis‐retinoic acid and all‐trans‐RA induced HDMEC to phagocytize and to increase the production of hydrogen peroxide and superoxide anion. These two retinoids also changed the morphology of endothelial cells from typical small compact cuboidal epithelioid cells to cells with larger cytoplasm and indistinct cell membranes. The retinoidstimulated HDMEC deposited increased amounts of extracellular matrix. All‐trans‐retinol and all‐trans‐retinol acetate did not significantly affect HDMEC in all parameters tested. The induction of these properties provides a new model with which to study how retinoids regulate gene expression using a normal, nontransformed cell line. © 1994 wiley‐Liss, Inc.
Heat sensitivity of Hela S3 Cell DNA topoisomerase II
Authors: Warters Raymond L. , Barrow Louis R. 
Published: February 2005

AbstractThe sensitivity of HeLa DNA topoisomerase II to 45°C heat shock was measured both in the intact cell and in vitro. In the intact cell, DNA topoisomerase II activity was estimated by measuring the formation and reversal of enzyme‐DNA cleavable complexes by alkaline filter elution of cells exposed to the enzyme poison 4′‐(9‐acridinylamino)(methanesulfon‐m‐anisidide). In vitro enzymatic activity was estimated by measuring changes in the topological state of plasmid and kinetoplast DNA produced by sonicates of nuclei from previously heated cells. The capacity of the enzyme to form, or reverse, enzyme‐DNA cleavable complexes was inactivated during 45°C heating with a reciprocal slope of 120 or 15 min, respectively. In vitro estimates of the activity of the enzyme from previously heated cells indicated that the enzyme was inactivated with a reciprocal slope of 99, 45, and 21 min after 45, 46 and 47°C heating, respectively. DNA topoisomerase I activity was inactivated with a reciprocal slope of 130 min at 45°C. The cumulative results indicate that during 45°C heat shock, thermal inactivation of neither DNA topoisomerase I nor II is rate limiting for either cell survival or for DNA replication. While DNA topoisomerase II is resistant in situ to heat inactivation, in vivo assays indicate that the enzyme's capacity to function in the intact cell may be compromised by hyperthermic changes in the enzyme's environment. © 1994 wiley‐Liss, Inc.
Understanding the dynamics of cellular responsiveness to modifications of metabolic substrates in perifusion
Authors: Brand Rhonda M. , Lyons R. H. , Midgley A. Rees 
Published: February 2005

AbstractA novel microperifusion system with capabilities for continuous, real‐time, potentiometric monitoring of extracellular hydrogen ion concentration has been used to define the response of HeLa cells to abrupt changes in extracellular energy sources or introduction of an inhibitor of glycolysis. Glycolytic inhibition, induced by removal of glucose or introduction of iodoacetate, each led to a rapid, continuous decrease in acid release. The response to iodoacetate took longer than removal of glucose, perhaps due to the time required for binding and activation. Once inhibition began, however, the rate of change was greater than following glucose removal. Conversely, recovery time following iodoacetate inhibition was much slower than with glucose removal. Unlike the response to short‐term glucose depletion, a second pulse of iodoacetate resulted in a faster response followed by an even longer recovery time. The response to switching between glucose and glutamine began almost without evident delay. The response patterns revealed that HeLa cells prefer glutamine to glucose, but, in the presence of both energy sources, some glucose continues to be used. In summary, these results indicate that continuous, real‐time monitoring of the kinetics of hydrogen‐ion release can be used to gain new insights into the dynamics of cellular response to perturbations of extracellular energy sources. © 1994 Wiley‐Liss, Inc.
Effects of epoxyeicosatrienoic acids on 86Rb uptake in renal epithelial cells
Authors: Staudinger R. , Abraham N. G. , Schwartzman M. L. , Escalante B. 
Published: February 2005

AbstractEpoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites formed endogenously via the cytochrome P450 pathway in rat, rabbit, and human kidney. We characterized the effects of the four regioisomeric EETs on ion transport in the renal epithelial cell line, LLC‐PK1. Among the EETs, 14, 15‐EET was the most potent inhibitor of 86Rb uptake. Its effect was concentration‐dependent (IC50 = 75 nM) and stereoselective to the 14S, 15R‐EET. Experiments measuring 14, 15‐EET–induced 86Rb uptake inhibition in the presence of inhibitors of Na+‐K+‐ATPase activity (ouabain), Na+‐K+‐Cl− cotransporter (furosemide), and Na+‐H+ exchanger (amiloride) suggested that 14, 15‐EET inhibits ion transport via an amiloride‐sensitive mechanism. These results, together with previous reports demonstrating their endogenous production in the kidney, suggest an important role for EETs, specifically 14, 15‐EET, in the regulation of ion and water reabsorption in the kidney and implicate their function in renal pathophysiology. © 1994 Wiley‐Liss, Inc.
Involvement of Na+, K+‐ATPase inhibition in K562 cell differentiation induced by bufalin
Authors: Numazawa Satoshi , Shinoki Masa‐Aki , Ito Hisatomi , Yoshida Takemi , Kuroiwa Yukio 
Published: February 2005

AbstractHuman leukemia K562 cell differentiation induction by naturally occurring bufadienolides purified from the Chinese drug Senso and synthetic bufalin derivatives was examined by a nitro blue tetrazolium reduction assay. Bufalin showed the strongest activity among all the bufadienolides tested in this study. The degree of the induction of nitro blue diformazan positive cells by the bufadienolides correlated well with their inhibitory activities against Na+, K+ ‐ATPase prepared from K562 cells in vitro. N+, K+ ‐ATPases from a variant K562 clone (ouabain resistant, OuaR) and murine leukemia cell line M1‐T22, which were insensitive to the bufadienolides in terms of growth inhibition and cell differentiation, appeared to be refractory to bufalin in vitro. A binding study of 3H‐bufalin and 3H‐ouabain revealed that saturated levels of both ligands associated with K562 cells were virtually similar; however, affinity of 3H‐bufalin was considerably higher than 3H‐ouabain. The saturated level of 3H‐bufalin observed in the OuaR cells was approximately half of that observed in K562 cells without a change in its affinity. Association of 3H‐bufalin with K562 cells was completely blocked by pretreatment of the cells with cold ouabain at concentrations saturating the binding sites. These results suggest that bufalin acts on the cells by binding to sites on the cell membrane which also bind ouabain. It is thus proposed that N+, K+ ‐ATPase inhibition is closely related to the initiation process in the induction of K562 cell differentiation induced by bufalin. © 1994 Wiley‐Liss, Inc.
Reactive oxygen metabolite‐induced toxicity to cultured bovine endothelial cells: Status of cellular iron in mediating injury
Authors: Hiraishi Hideyuki , Terano Akira , Razandi Mahnaz , Pedram Ali , Sugimoto Tsuneaki , Harada Takashi , Ivey Kevin J. 
Published: February 2005

AbstractWe aimed to determine the status of iron in mediating oxidant‐induced damage to cultured bovine aortic endothelial cells. Chromium‐51‐labeled cells were exposed to reaction mixtures of xanthine oxidase/hypoxanthine and glucose oxidase/glucose; these produce superoxide and hydrogen peroxide, or hydrogen peroxide, respectively. Xanthine oxidase caused a dose dependent increase of 51Cr release. Damage was prevented by allopurinol, oxypurinol, and extracellular catalase, but not by superoxide dismutase. Prevention of xanthine oxidase‐in‐duced damage by catalase was blocked by an inhibitor of catalase, aminotriazole. Glucose oxidase also caused a dose‐dependent increase of 51Ci release. Glucose oxidase‐induced injury, which was catalase‐inhibitable, was not prevented by extracellular superoxide dismutase. Both addition of and pretreatment with deferoxamine (a chelator of Fe3+) prevented glucose oxidase‐induced injury. The presence of phenanthroline (a chelator of divalent Fe2+) prevented glucose oxidase‐induced 51Cr release, whereas pretreatment with the agent did not. Apotransferrin (a membrane impermeable iron binding protein) failed to influence damage. Neither deferoxamine nor phenanthroline influenced cellular antioxidant defenses, or inhibited lysis by non‐oxidant toxic agents. Treatment with allopurinol and oxypurinol, which inhibited cellular xanthine oxidase, failed to prevent glucose oxidase injury. We conclude that (1) among the oxygen species extracellularly generated by xanthine oxidase/hypoxanthine, hydrogen peroxide induces damage via a reaction on cellular iron; (2) deferoxamine and phenanthroline protect cells by chelating Fe3+ and Fe2+, respectively; and (3) reduction of cellular stored iron (Fe3+) to Fe2+ may be a prerequisite for mediation of oxidantinduced injury, but this occurs independently of extracellular superoxide or cellular xanthine oxidase‐derived superoxide. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Laminin SIKVAV peptide‐induced angiogenesis in vivo is potentiated by neutrophils
Authors: Kibbey Maura C. , Kleinman Hynda K. , Corcoran Marta L. , Wahl Larry M. 
Published: February 2005

AbstractAngiogenesis has been investigated in vivo using subcutaneously injected reconstituted basement membrane (Matrigel) supplemented with angiogenic factors. Previously we found that the laminin‐derived synthetic peptide containing SIKVAV (ser‐ile‐lys‐val‐ala‐val) promoted angiogenesis in vivo. In parallel studies, it was observed that new vessel formation in response to this peptide occurred several days after basic fibroblast growth factor‐induced angiogenesis. Since this delay suggested that SIKVAV‐induced angiogenesis may be secondary to other events, we investigated here earlier time points to determine if both indirect and direct mechanisms of angiogenesis are involved. We found that neutrophils are continuously recruited to the SIKVAV‐containing plugs between 4 hours to 3 days following the initial injection. By day 7, columns of endothelial cells begin to migrate into the plug and form small blood vessels. In contrast, neutropenic mice had a 62% reduction in SIKVAV‐induced angiogenesis when compared to control mice. Freshly isolated neutrophils also degraded laminin, the major component of the basement membrane Matrigel. These cells also produced factors in response to SIKVAV peptide which induced proliferation of human umbilical vein endothelial cells relative to a control peptide. In vitro experiments utilizing human neutrophils demonstrated that these cells migrate to the SIKVAV peptide and possess a specific cell surface SIKVAV binding protein of ∼56 kD. These data suggest that neutrophils are induced to migrate to the Matrigel plugs, at least in part, by SIKVAV peptide, where they may release their own angiogenic factors and degrade the matrix, thus physically facilitating cell migration and liberating additional angiogenic matrix fragments and/or cytokines. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America
Inhibition of angiogenesis by tissue inhibitor of metalloproteinase
Authors: Johnson Mark D. , Kim Hyeong‐Reh Choi , Chesler Louis , Tsao‐Wu Gladys , Polverini Peter J. , Bouck Noel 
Published: February 2005

AbstractMatrix proteases play a critical role in cell invasion and migration, including the process of angiogenesis. The ability of specific factors to induce angiogenic responses correlates with their stimulation of matrix protease synthesis and release. Using an in vivo angiogenesis assay, the endothelial cell response to known angiogenic factors, basic fibroblast growth factor (bfGF) and adipocyte conditioned medium, was blocked by an inhibitor of matrix metalloproteinase activity, TIMP‐1. The TIMP effect was mediated, at least in part, through the inhibition of endothelial cell migration, as determined by the ability of TIMP to block chemotaxis in a Boyden chamber assay. These results indicate that the inhibition of migration is a direct effect on the endothelial cells and does not require accessory cells. An additional observation was that the RNA levels for TIMP were significantly reduced in differentiated adipocytes, compared to undifferentiated F442A controls. Therefore, the acquisition of an angiogenic phenotype may involve not only the induction of positive factors, but also the suppression of angiogenesis inhibitors. © 1994 Wiley‐Liss, Inc.
Senescence and cell density of human diploid fibroblasts influence metabolism of insulin‐like growth factor binding proteins
Authors: Grigoriev Vitalii G. , Moerman Elena J. , Goldstein Samuel 
Published: February 2005

AbstractIn order to analyze changes in metabolism of insulin‐like growth factor binding proteins (IGFBPs) related to cell senescence and cell density, we compared human diploid fibroblasts (HDF) in the proliferatively vigorous first half (young cells) and senescent HDF in the last 10% (old cells) of the replicative lifespan after seeding cells over an eighfold range and proliferation to high density. Increasing the seeding cell density of both young and old HDF led to elevated rates of IGFBP‐3 secretion, an increasing ratio of the 42/38 kDa species of IGFBP‐3, and degradation of all species of IGFBPs derived from both the fetal bovine serum component of the culture medium and from HDF. At a given seeding density old HDF produced more IGFBP‐3 and degraded more IGFBPs than young HDF. IGFBP‐4 was degraded by a protease that appeared to be different from the protease(s) involved in degradation of the other IGFBPs. Young HDF at all seeding densities contained a cell‐associated 29 kDa IGFBP, whereas this protein could not be detected in old cells. Thus, although certain changes in IGFBP metabolism are similar in young HDF seeded at high densities and in old HDF, young and old phenotypes can be distinguished by characteristic qualitative and quantitative changes in IGFBPs derived from fetal bovine serum and from HDF. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America
Stable differentiation of a human colon adenocarcinoma cell line by sodium butyrate is associated with multidrug resistance
Authors: Ho Samuel B. , Yan Pei‐Sha , Dahiya Rajvir , Neuschwander‐Tetri Brent A. , Basbaum Carol , Kim Young S. 
Published: February 2005

AbstractColorectal cancers are often composed of cell types representing various differentiated cell lineages, however little is known concerning the relationship of differentiation and drug resistance in these cancers. The present study was performed to develop and characterize a stable, differentiated clone of the human colon cancer cell line LS174T and to characterize the drug resistance of this cell line in relation to its undifferentiated parental cell line. LS174T cell line was treated with the differentiating agent sodium butyrate (0.5 mM) for 30 days, then recultured in standard medium. Foci of flat‐appearing cells appeared and were isolated using cloning rings, and subcloned. One subclone was designated LS174T‐D. The LS174T‐D clone maintains a stable, differentiated phenotype in standard culture conditions in the absence of sodium butyrate. It is characterized by the formation of a polarized monolayer with dome formation and the presence of prominent apical microvilli and tight junctions. This cell line demonstrated reduced growth in soft agar and nude mice compared with the parental cell line. LS174T‐D cells expressed immunoreactive intestinal mucin antigens and brush border enzymes dipeptidyl aminopeptidase (DAP)‐IV and aminopeptidase. The activities of DAP‐IV and aminopeptidase were increased 5.6‐fold and 3.4‐fold, respectively, in LS174T‐D compared with parental cells. Proliferation assays demonstrated that, compared with the parental cell line, LS174T‐D cells were more resistant to doxorubicin (93‐fold), cisplatin (23‐fold), 5‐fluorouracil (12‐fold), 5‐fluorodeoxyuridine (31‐fold), and methotrexate (12.5‐fold). Intracellular uptake of (3H)‐5‐fluorodeoxyuridine did not differ significantly in the differentiated and undifferentiated cell lines. Levels of mdr‐1 p‐glycoprotein measured by Western blot and RNA Northern blot assays were also similarly low in both cell lines. However, total glutathione content and glutathione‐S‐transferase activities were increased in LS174T‐D cells by sixfold and threefold, respectively, compared with parental cells. Depletion of glutathione by pretreatment with DL‐buthionine sulfoximine reversed LS174T‐D resistance to cisplatin. Long‐term treatment with sodium butyrate induces or selects for colon cancer cells with features of enterocytic differentiation. This stably differentiated cell line is associated with glutathione‐mediated multidrug resistance, and provides a model for further studies of differentiation in normal and cancerous colon. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America
Regulation of γ‐actin gene expression by insulin
Authors: Messina Joseph L. 
Published: February 2005

AbstractInsulin exerts rapid effects on cellular metabolism and can cause morphological changes by inducing rearrangements of cytoskeletal components. The regulation of specific cytoskeletal genes by insulin, however, has not been studied extensively. In the present work insulin was found to rapidly, but transiently, increase transcription of the cytoskeletal γ‐actin gene in rat H4IIE (H4) hepatoma cells. Insulin‐induced transcription of the γ‐actin gene was evident within 5 min and was maximal by 15 min at 10‐fold above control levels. The stimulation of transcription was transient, with a return towards basal levels by 120 min. Transcription of γ‐actin was increased at insulin concentrations as low as 1 × 10−11 M and was maximal at 1 × 10−9 to 1 × 10−8 M. Transcription of several control genes (skeletal and cardiac α‐actin and β‐tubulin) were unaltered by insulin administration. Messenger RNA (mRNA) levels for the γ‐actin gene increased, but to a lesser degree than transcription. Since the γ‐actin message is an abundant and stable mRNA, its levels would not be expected to change dramatically from a transient induction of transcription. Like insulin, phorbol esters transiently increased transcription of the γ‐actin gene. In addition, pretreatment of cells with phorbol esters for 24 h reduced the ability of insulin to induce γ‐actin transcription. These data support our hypothesis that insulin and phorbol esters share intracellular signalling pathways in the control of transcription of specific genes. © 1994 Wiley‐Liss, Inc.
Cultured rat hepatocytes adapt their cellular glycolytic activity and adenylate energy status to tissue oxygen tension: Influences of extracellular matrix components, insulin and glucagon
Authors: Ohno Kouji , Maier Peter 
Published: February 2005

AbstractThe influence of extracellular matrix components, insulin, and glucagon on the cellular response to periportal‐ or pericentral‐equivalent tissue oxygen tension was investigated in freshly isolated rat hepatocytes cultured at 13% O2 or 4% O2 in Teflon membrane dishes. With extended culture time, significant increases in lactate release and cellular lactate content were observed in cultures at 4% O2 compared with 13% O2. This shift toward glycolysis was detectable when hepatocytes were cultured on dishes coated with rat liver crude membrane fraction (CMF/COL) but not in collagen type I‐coated dishes. This indicates that extracellular matrix components are involved in the process of adaptation. ATP and total adenylate content in cells cultured at 4% O2 were up to 40% lower than in cells cultured at 13% O2. However, the adenylate energy charge was not affected, suggesting that an adequate energy supply was maintained also in hepatocytes cultured at pericentral‐equivalent oxygen tension. This adaptation was reversible. When hepatocytes were transferred either from 4% to 13% O2 or from 13% to 4% O2, they adapted the corresponding metabolic profile to the new oxygen tension within 2 days. This demonstrates that hepatocytes are not fully unidirectionally programmed. The modulation of the glycolytic activity by insulin and glucagon was effective in cultures at pericentral‐equivalent oxygen tension (4% O2) only. Insulin (0.1‐100 nM) counteracted the effect of insulin in a dose‐dependent manner. Clearly, oxygen tension is the principal regulator in the hepatic glycolytic activity, whereas the hormones (insulin and glucagon) act as secondary modulators. © 1994 Wiley‐Liss, Inc.
Enhancement of proliferation in cultures of Chinook salmon embryo cells by interactions between inosine and bovine sera
Authors: Ganssin R. C. , Tran Q. H. , Rabgey T. F. , Bols N. C. 
Published: February 2005

AbstractThe influence of inosine on DNA synthesis by Chinook salmon embryo cells (CHSE‐214) was investigated because previously cell number was shown to increase from six‐ to thirtyfold if inosine was added to the basal medium (L‐15) supplemented with either dialyzed fetal bovine serum (dFBS), calf serum (CS), or dCS. Relative to L‐15, 3H‐thymidine incorporation was inhibited by these sera alone but elevated in nondialyzed (intact) FBS. Inosine at 10 μM stimulated 3H‐thymidine incorporation from ten‐ to seventyfold in dFBS, CS, and dCS but was only slightly stimulatory in FBS and in L‐15 alone. As well as inosine, hypoxanthine, cIMP, IMP, IDP, and ITP were just as stimulatory, but the nonsalvageable purines (xanthine, xanthosine, and XMP) were not. The stimulatory action of inosine was highest in low density cultures. Dipyridamole and S‐(p‐nitrobenzyl)‐6‐thioinosine (NBTI), inhibitors of facilitated nonconcentrative nucleoside transport, did not completely block the enhancement of cell number by inosine and by themselves increased proliferation in CS and dCS. Overall, these results suggest that exogenous inosine promoted CHSE‐214 proliferation by overcoming factors in the nondialyzable fraction of sera that led to purine loss and by raising intracelular purine nucleotides to levels necessary for cells to respond to growth factors in the nondialyzable fraction of sera. © 1994 Wiley‐Liss, Inc.