bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abnormal extracellular matrix and excessive growth of human adult polycystic kidney disease epithelia
Authors: Wilson Patricia D. , Hreniuk David , Gabow Patricia A. 
Published: February 2005

AbstractHuman autosomal dominant polycystic kidney disease (ADPKD) epithelia were grown in primary monolayer cultures and their properties compared with intact kidney epithelial cultures derived from individually microdissected normal human kidney proximal convoluted tubules (PCT), proximal straight tubules (PST), and cortical collecting tubules (CCT). In vivo, ADPKD cyst epithelia exhibited a thickened basement membrane, and immunofluorescence demonstrated the presence of laminin, fibronectin, type IV collagen, and heparan sulfate proteoglycan in basement membranes and type I collagen in the interstitium. ADPKD epithelia grown in culture synthesized and secreted basally a unique, extracellular matrix that took the form of proteinaceous spheroids when the cells were grown on dried, type I collagen. Incorporation of H2[S35O4] into basement membrane extracts was increased more than ten‐fold in ADPKD epithelia by comparison to normal PST and CCT. In addition to incorporation into the normal tubular basement membrane 220 kD band, radioactivity was also seen at 175 kD and 150 kD in ADPKD extracts. Growth in culture of cyst‐lining ADPKD epithelia was more rapid than normal tubules, and was abnormal since there was no absolute requirement for added extracellular matrix. However, when ADPKD epithelia were grown on different, exogenous matrix protein components, a profound influence on both structure and epithelial cell proliferation was seen. Growth on a complete basement membrane three‐dimensional gel derived from the Engelbreth‐Holm‐Swarm (EHS) sarcoma led to a reduction in the numbers of spheroids and increase in amorphous filaments. Incorporation of [3H]‐thymidine into ADPKD epithelia was greater than into normal PCT, PST, and CCT and was also greatly modified by the type of extracellular matrix components provided. In studies using single matrix components, the strongest proliferative response was seen when ADPKD epithelia were plated on type I collagen > type IV collagen > fibronectin > laminin. These findings suggest that the excessive growth of cystlining epithelia may be, at least in part, a result of abnormal basement membrane and extracellular matrix production by ADPKD cells.
Treatment of myeloid leukemic cells with the phosphatase inhibitor okadaic acid induces cell cycle arrest at either G1/S or G2/M depending on dose
Authors: Ishida Yuji , Furukawa Yusuke , Decaprio James A. , Saito Masaki , Griffin James D. 
Published: February 2005

AbstractThe phosphatase inhibitor okadaic acid was found to induce cell cycle arrest of human myeloid leukemic cell lines HL‐60 and U937 in a concentration‐ and time‐dependent manner. Exposure to low concentrations of okadaic acid (2–8nM) for 24–48 hr caused >70% of cells to arrest at G2/M, with up to 40% of the cells arrested in early mitosis. Cell viability decreased rapidly after 48 hr of treatment, and morphological and DNA structure analysis indicated that this was primarily due to the induction of apoptosis. The cells arrested in mitosis by 8 nM okadaic acid could be highly enriched by density gradient centrifugation and underwent apoptosis when further cultured either with or without okadaic acid, indicating that the effects of okadaic acid were irreversible. In contrast to the effects of low concentrations of okadaic acid, high concentrations (500 nM), inhibited proliferation in less than 3 hr. Remarkably, the majority of cells also entered a mitosis‐like state characterized by dissolution of the nuclear membrane and condensation and partial separation of chromosomes. However, these cells had a diploid content of DNA, indicating that the cell cycle arrest occurred at G1/S with premature chromosome condensation (PCC), rather than at G2/M. If cells were first blocked at G1/S with hydroxyurea and then treated with okadaic acid, >90% developed PCC in less than 3 hr without replicating their DNA. Caffeine was not able to induce PCC in these cells, either with or without prior inhibition of DNA synthesis. These results provide further evidence that an interacting system of cell cycle associated phosphatases and kinases control the initiation of each phase of the cell cycle in higher eukaryotes and further suggest that okadaic acid will be useful in manipulating the cell cycle of leukemic cells.
Cell cycle dependent gene expression in quiescent stimulated and asynchronously cycling arterial smooth muscle cells in culture
Authors: Campan Michel , Desgranges Claude , Gadeau Alain‐Pierre , Millet Dominique , Belloc Francis 
Published: February 2005

AbstractThe expression of a set of cell cycle dependent (CCD) genes (c‐fos, c‐myc, ornithine decarboxylase (ODC), and thymidine kinase (TK)) was comparatively studied in cultured arterial smooth muscle cells (SMC) during exit from quiescence and exponential proliferation. These genes, which were not expressed in quiescent SMC, were chronologically induced after serum stimulation. c‐fos mRNA were rapidly and transiently expressed very early in the G1 phase; c‐myc and ODC peaked a few hours after serum stimulation and then remained at an intermediary level throughout the first cell cycle; TK mRNA and activity then appeared at the G1/S boundary and peak in G2/M phases. Except for c‐fos, the other genes were also expressed in asynchronously cycling SMC (ACSMC); their expression was studied in elutriated subpopulations representative of cell cycle progression. c‐fos mRNA were undetectable in any sorted subpopulations, even in the pure early G1 population. Despite a slight increase as the cell cycle advanced, c‐myc and ODC genes were expressed throughout the ACSMC cell cycle. A faint TK activity was found in G1 subpopulations and increased in populations enriched in other phases; in contrast, TK mRNA remained highly expressed in all elutriated subpopulations. This study demonstrates significant modulations in CCD gene expression between quiescent stimulated and asynchronously cycling SMC in culture. This suggests that the events occurring during the emergence of SMC from quiescence are probably different from those in the G1 phase of ACSMC.
Vasoactive intestinal peptide and forskolin regulate proliferation of the HT29 human colon adenocarcinoma cell line
Authors: Gamet Laurence , Murat Jean‐Claude , Remaury Anne , Remesy Christian , Valet Philippe , Paris Hervé , Denis‐Pouxviel Colette 
Published: February 2005

AbstractAlthough several lines of evidence implicate cAMP in the regulation of intestinal cell proliferation, the precise role of this second messenger in the control of the human colon cancer cell cycle is still unclear. In order to investigate the role of cAMP in HT29 cell proliferation, we have tested the effect of vasoactive intestinal peptide (VIP) and forskolin on DNA synthesis and cell number, focusing on the time‐dependent efficacy of the treatment. The cells were arrested in GO/G1 phase by incubation for 24 h in serum‐free medium and proliferation was re‐initiated by addition of either 85 nM insulin or 0.5% fetal calf serum. In the presence of fetal calf serum, G1/S transition was found to occur earlier than with insulin. Exposure of the HT29 cells to 10−5 M forskolin in the early stages of growth induction (within 12 h from FCS addition or within 14 h from insulin treatment) resulted in a significant inhibition of DNA synthesis and a delayed entry in the S phase. By contrast, VIP (10−7 M) was inhibitory only when added within a narrow window (10 to 12 h or 12 to 14 h following FCS or insulin addition, respectively). The difference in efficiency of forskolin and VIP to inhibit cell proliferation may be correlated with their own potency to promote long‐lasting cAMP accumulation. The combination of VIP plus forskolin had synergistic effects on both cAMP accumulation and cell‐growth inhibition. Taken together, our data indicate that cAMP may act at a step in the late G1 or G1/S transition.
Shear‐induced platelet‐derived growth factor gene expression in human endothelial cells is mediated by protein kinase C
Authors: Hsieh Hsyue‐Jen , Li Nan‐Qian , Frangos John A. 
Published: February 2005

AbstractOur previous studies have shown that steady shear stress causes a transient increase of platelet‐derived growth factor (PDGF) A and B chain mRNA levels in human umbilical vein endothelial cells (HUVEC). In the present study, we elucidated the signaling pathway of shear stress in HUVEC by examining the roles of protein kineses, intracellular calcium, cyclooxygenase, and guanine nucleotide‐binding proteins (G proteins) in the PDGF gene induction by shear. The protein kinase C inhibitors, H7 and staurosporine, strongly inhibited the shear‐induced PDGF gene expression in HUVEC. In contrast, HA1004, a cAMP‐ and cGMP‐dependent protein kineses inhibitor, was only slightly inhibitory. BAPTA/AM, an intracellular calcium chelator, partially (50%) inhibited the shear‐induced PDGF gene expression. The cyclooxygenase inhibitors, ibuprofen and indomethacin, were slightly inhibitory. A 35–50% inhibition of shear‐induced PDGF gene expression was found with GDP‐β‐S, an inhibitor of G proteins. These results suggest that shear‐induced PDGF gene expression in HUVEC is mainly mediated by protein kinase C activation and requires intracellular calcium. Furthermore, G proteins seem to be involved in this process, whereas prostaglandin synthesis via cyclooxygenase pathway is not. We propose a mechanism of shear‐induced gene expression in HUVEC: Shear stress, either directly or indirectly (G protein‐mediated), enhances the membrane phosphoinositide turnover via phos‐pholipase C, producing diacylglycerol, an activator of protein kinase C. The activated protein kinase C then triggers the subsequent PDGF gene expression.
The differential effects of N,N‐dimethylformamide and transforming growth factor‐β1 on a human ovarian cancer cell line (HOC‐7)
Authors: Grunt Thomas W. , Somay Canatay , Ellinger Adolf , Pavelka Margit , Dittrich Evelyn , Dittrich Christian 
Published: February 2005

AbstractWe have compared the effects of N, N‐dimethylformamide (DMF) and transforming growth factor (TGF)‐β1 on the growth and phenotype of HOC‐7 ovarian cancer cells. Previous density gradient fractionation of untreated HOC‐7 cells suggested that rapidly growing small polygonal medium density cells revert spontaneously into less malignant flattened low density cells. Here we demonstrate that DMF and TGF‐β1 induce similar flattened cell phenotypes. Both agents induce qualitatively similar alterations in the cells. DMF, however, exerted stronger effects than TGF‐β1. The cells become flattened, develop cytoplasmic extensions, and reduce DNA‐synthesis as well as anchorage‐dependent and ‐independent growth. These effects are reversible after removal of the inducers, indicating that the cells have not become terminally differentiated. Electron microscopy demonstrates prominent filament bundles in treated cells. Immunofluorescence further shows that these cells contain large amounts of cytokeratin. Immunocytochemistry and ELISA demonstrate 1‐ to 5‐fold higher amounts of desmoplakin and fibronectin after DMF‐ or TGF‐β1‐exposure. The described differentiation‐like responses of HOC‐7 cells can be used for recognition of pharmacologically induced maturation of ovarian cancer cells. © 1992 Wiley‐Liss, Inc.
Cyclical strain effects on production of vasoactive materials in cultured endothelial cells
Authors: Carosi Joseph A. , Eskin Suzanne G. , McIntire Larry V. 
Published: February 2005

AbstractMechanical forces due to fluid flow and cyclical strain can alter endothelial cell morphology and function, including the release of vasoactive materials endothelin, prostacyclin (PGI2), and tissue plasminogen activator (t‐PA). In this study, effects of cyclical strain were modeled by culturing bovine aortic endothelial cells on fibronectin‐coated elastic membranes of silicone rubber (Silastic®) or poly‐etherurethane urea (Mitrathane™). After growing to confluence under static conditions of 37°C in humidified air with 5% CO2, cells were strained cyclically at membrane elongations of 5% or 10% for 24 hours at 1 Hz. Controls were maintained under static conditions or were exposed to fluid motions similar to the strained cells but without stretching. Secretion rates were constant throughout experiments in the strain chamber with no initial burst in metabolism associated with the initiation of strain. Secretion rates were not altered by choice of elastic membrane. At a physiological level of 10% cyclical strain, prostacyclin and endothelian secretion rates were increased by 2.5‐fold and 1.7‐fold, respectively, above stationary controls. Endothelin production demonstrated a dose‐dependent response with cyclical strain, while PGI2 appeared to require a threshold strain before an increase in secretion occurred. No significant differences in t‐PA levels were seen in cyclically strained cells compared with controls. These results indicate that endothelial cells respond metabolically to cyclical strain and suggest that mechanical strain may modulate secretion of selective vasoactive materials by vascular endothelial cells. © 1992 Wiley‐Liss, Inc.
Changes in luminal flow rate modulate basal and bradykinin‐stimulated cell [Ca2+] in aortic endothelium
Authors: Oliver Juan A. , Chase Herbert S. 
Published: February 2005

AbstractHemodynamic forces influence many endothelial cell functions. The coupling between hemodynamic forces and cell function could be mediated by mechano‐sensitive ion channels present in the plasma membrane of endothelial cells. Because one of these channels is permeable to Ca2+, we tested whether hemodynamic forces influence endothelial cell Ca2+ ([Ca2+]i). Bovine aortic endothelial cells were grown inside cylindrical glass tubes, loaded with fura‐2, and perfused at different pressures and flow rates on the stage of a fluorescence microscope. Decreasing flow from 110 to 2 ml.min−1 raised [Ca2+]i from 57 ± 11 to 186 ± 29 nM (mean ± SEM, p < 0.01) by increasing the entry of extracellular Ca2+ into the cytoplasm. Increasing flow from 2 to 110 ml.min−1 transiently decreased [Ca2+]i from 62 ± 3 to 33 ± 5 nM (p < 0.01) apparently due to reduced Ca2+ entry and concomitant extrusion by the plasma membrane Ca2+‐ATPase. The rise in [Ca2+]i induced by bradykinin was magnified during a decrease in flow; in control cells, 10−7 M bradykinin increased [Ca2+]i by 162 ± 26 nM, whereas [Ca2+]i increased 350 ± 67 nM (p < 0.05) in cells previously exposed to 110 ml.min−1. These observations suggest that flow‐induced changes in [Ca2+]i might be a signal‐transduction mechanism for endothelial functions responsive to hemodynamic forces and may also modulate the magnitude of hormonally mediated increases in [Ca2+]i. © 1992 Wiley‐Liss, Inc.
Secretion of stromelysin by cultured dermal papilla cells: Differential regulation by growth factors and functional role in mitogen‐induced cell proliferation
Authors: Goodman Linda V. , Ledbetter Steven R. 
Published: February 2005

AbstractTo understand better the molecular nature of the epithelial‐mesenchymal interactions that govern folliculogenesis and hair growth, we have studied the behavior of cultured rat dermal papilla cells (rDP), the mesenchymal component of the hair follicle. Basic fibroblast growth factor (bFGF) and platelet‐derived growth factor (PDGF) both potentiated the growth of rDP in culture, and transforming growth factor‐β (TGF‐β) inhibited rDP proliferation. Biosynthetic labeling studies demonstrated that both PDGF and bFGF induced synthesis of a major secreted protein(s) with Mr = 55–60 kD. It was noted that PDGF and bFGF differentially regulated synthesis of this major secreted protein; PDGF‐mediated induction was found to be transient, while bFGF allowed prolonged synthesis of the protein. Sodium dodecyl sulfate (SDS)‐substrate gel analysis of rDP‐conditioned media revealed that this protein is a metalloproteinase with casienolytic activity and Mr ≈︁ 51 kD (unreduced). We have identified the growth factor‐regulated rDP protein as the matrix metalloproteinase stromelysin by immunoprecipitation. Northern analysis established that increased secretion of stromelysin was accompanied by an increased expression of stromelysin‐specific mRNA. Remarkably, stromelysin antisera interfere with stimulation of dermal papilla cell growth, demonstrating that stromelysin production serves a functional role in mitogen‐induced proliferation in these cells. These findings provide insight into the mechanism by which the connective tissue remodeling required for formation of hair embryonically and the postembryonic hair cycle may be regulated. © 1992 Wiley‐Liss, Inc.
Repression of SV40 T oncoprotein expression by DMSO
Authors: Witte Michael M. , Parker Robert F. , Wang Hanlin , Scott Robert E. 
Published: February 2005

AbstractSV40 large T oncoprotein‐transformed murine mesenchymal 3T3 T stem cells (CSV3 cells) can be induced to growth arrest and then differentiate into adipocytes. When differentiation occurs, SV40 T oncoprotein expression is repressed (Estervig et al., J Virol 63:2713, 1989). To determine if repression of T oncoprotein expression can also be induced pharmacologically, the effect of a variety of agents that have been reported to effect differentiation in various cell types but not in 3T3 T or CSV3 cells was tested. This rationale suggests that if any of these agents repress T oncoprotein expression in CSV3 cells, then the results would establish that repression of T oncoprotein expression can be mediated by mechanisms independent of overt differentiation. The results show that dimethylsulfoxide (DMSO) is the only agent tested that represses T oncoprotein expression in CSV3 cells. Repression occurs in a dosage‐dependent manner within 24–96 hours after exposure to DMSO. The effect of DMSO on T oncoprotein expression is mediated by posttranslational mechanisms that decrease the stability of the T oncoprotein. DMSO‐induced repression of T oncoprotein expression is also associated with reversion of the transformed phenotype in CSV3 cells as demonstrated by the loss of responsiveness to a specific transformation‐associated mitogen. These data support the conclusion that the pharmacological repression of T oncoprotein expression represents a form of cancer suppressor activity that can be mediated by a distinct molecular mechanism. © 1992 Wiley‐Liss, Inc.
Peroxisome assembly mutations in humans: Structural heterogeneity in Zellweger syndrome
Authors: Santos Manuel J. , Hoefler Sigrid , Moser Ann B. , Moser Hugo W. , Lazarow Paul B. 
Published: February 2005

AbstractEmpty membrane ghosts of peroxisomes were found in fibroblasts from a patient with Zellweger's syndrome, a genetic disease of humans (Santos et al: Science 239:1536–1538, 1988). Import of soluble matrix proteins into the organelle was defective. We have now studied fibroblasts from seven patients representing five complementation groups of the syndrome (defined by complementation for peroxisome enzyme function). We find that empty peroxisome ghosts are present in all seven cell samples. Three patients, representing three complementation groups, give the same membrane pattern by immunofluorescence: few large ghosts. Three other patients, representing two complementation groups, give a second pattern: many large ghosts. The seventh patient's pattern is distinct. Thus, all seven of these patients exhibit Peroxisome IMport (PIM) mutations. Since membrane assembly occurs in these cells, the results indicate that biogenesis of organelle content and membrane proteins proceed by different mechanisms. Growth and division of the empty peroxisomal membrane must occur, but are modified by the mutations (ghost size and abundance vary). Cell fusion and immunofluorescence analyses of peroxisome size and catalase packaging formally demonstrate genetic complementation groups for peroxisome assembly in Zellweger syndrome. © 1992 Wiley‐Liss, Inc.
Multipotent marrow stromal cell line is able to induce hematopoiesis in vivo
Authors: Umezawa Akihiro , Maruyama Tatsuya , Segawa Kaoru , Shadduck Richard K. , Waheed Abdul , Hata Jun‐Ichi 
Published: February 2005

AbstractSeveral murine marrow stromal cells were established from murine bone marrow cultures. Stromal cell lines transfected with a tumor‐inducing polyoma virus middle T antigen (MTAg) were inoculated into nude mice subcutaneously. KUSA‐MTAg cells, one of these cell lines, led to the rapid local development of bone marrow consisting of trilineage hemantopoietic cells and bone; other cell lines produced spindle cell sarcoma or hemangiosarcoma. These results suggested that a single stromal cell line, KUSA‐MTAg cells, may induce hematopoietic stem cells or early progenitors of three lineages of hematopoietic cells in vivo. Interestingly, untransfected KUSA cells expressed three new mesenchymal phenotypes, osteocytes, adipocytes, and myotubes, after treatment with 5‐azacytidine. © 1992 Wiley‐Liss, Inc.
Mechanism of zinc uptake by microvilli isolated from human term placenta
Authors: Aslam Nadim , McArdle Harry J. 
Published: February 2005

AbstractThe mechanism of zinc (Zn) uptake by microvillous membrane vesicles prepared from human term placenta has been studied. The uptake was complex, with two processes being identified. In the first process, uptake was rapid, reaching equilibrium within 2 min, and was temperature dependent, with a Q10 of 1.5. Equilibrium Zn levels were sensitive to osmotic pressure, with Zn binding at infinite osmolarity being 69% iso‐osmotic value. The uptake was saturable, with a Vmax of 58 ± 2 nmol/mg protein/min and an apparent Kt of 128 ± 13 μM. Uptake was inhibited by increasing extravesicular K+ concentration, dropping from 0.91 ± 0.03 nmol/mg/min at 0 extravesicular K+ to 0.47 ± 0.03 at an extravesicular K+ concentration of 150 mM ([Zn] = 1.0 μM). In the presence of both valinomycin, an electrogenic ionophore, and nigericin, an electroneutral exchanger, an outwardly directed K+ gradient stimulated Zn uptake. Similarly, preloading vesicles with Zn and imposing an inward gradient resulted in a temperature dependent efflux of Zn. The data suggest that there is a K+ dependent Zn transporter in vesicle membranes, and we suggest that the evidence is biased in favour of a Zn/K+ exchanger rather than Zn being dependent on the membrane potential. © 1992 Wiley‐Liss, Inc.
Identification of multiple PKC isoforms in Swiss 3T3 cells: Differential down‐regulation by phorbol ester
Authors: Olivier Andrée R. , Parker Peter J. 
Published: February 2005

AbstractThe expression of members of the Ca2+ and phospholipid‐dependent protein kinase (PKC) family were studied in murine Swiss 3T3 cells. In addition to PKC‐α, the presence of immunoreactive PKC‐δ, ‐ε, and ζ was detected. Treatment with 500 nM 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) led to the down‐regulation of α, δ, and ε isoforms, but not that of ζ. Higher concentrations of TPA similarly had no effect on the level of PKC‐ζ. In contrast to PKC‐α, the membrane localization of PKC‐δ, ‐ε, and ‐ζ was not enhanced by extraction in Ca2+‐containing buffers, whereas acute TPA treatment increased membrane association of PKC‐α, ‐δ, and ‐ε but not that of PKC‐ζ. © 1992 Wiley‐Liss, Inc.