bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential induction of stromelysin mRNA by bovine articular chondrocytes treated with interferon‐γ and interleukin‐1α
Authors: Quintavalla J. C. , Berg R. A. , Beavis A. J. , Piccoli S. P. , Rediske J. J. , Kurkinen M. , Patrick R. A. , Robertson F. M. 
Published: February 2005

AbstractArticular chondrocytes from rheumatoid joints have been shown to express class II major histocompatibility (MHC) antigens that were correlated with the presence of interferon‐gamma (IFN‐γ) in the inflamed joint. Chondrocytes expressing MHC antigens function as antigens function as antigen presenting cells and thus stimulate lymphocyte proliferation. These responses suggest a powerful role for the IFN‐γ stimulation of chondrocytes. The present studies were designed to examine the functional role of chondrocytes exposed to IFN‐γ during cartilage degradation that occurs in synovial disease. Destruction of cartilage in arthritis is partially attributable to metalloproteinases released by the chondrocytes in response to interleukin‐1 (IL‐1). Bovine articular chondrocytes treated with interleukin‐1 alpha (IL‐1α) produced enhanced levels of stromelysin mRNA, however, Northern blots could not determine the percentage of cells responding. Exposure of bovine articular chondrocytes to IFN‐γ induced the expression of bovine HLA‐DR (boHLA‐DR) antigen in 50% of the cells. Using a modified cell sorting technique, chondrocytes that expressed class II MHC antigens produced two fold greater stromelysin mRNA than chondrocytes that did not express this antigen. In contrast, collagen type II mRNA levels were similar in chondrocytes, regardless of the expression of class II MHC antigens. In situ hybridization studies showed that less than half of all cartilage chondrocytes were induced to synthesize stromelysin mRNA. These observations suggest that IFN‐γ stimulates specific subpopulations of chondrocytes to be functionally active in inflammation‐induced metalloprotease secretion. © 1993 Wiley‐Liss, Inc.
Increase in epidermal growth factor receptor and its messenger ribonucleic acid levels with differentiation of human trophoblast cells in culture
Authors: Alsat Eliane , Haziza Jocelyne , Evain‐Brion Danièle 
Published: February 2005

AbstractEpidermal growth factor receptor (EGFR) expression was studied during the differentiation of human trophoblast cells in culture. In vitro, intravillous mononuclear cytotrophoblasts aggregate and fuse within 24 h to form a syncytium. This morphological differentiation was associated with a significant twofold increase in specific 125I‐EGF binding capacity (P < 0.01). Scatchard analyses showed an apparent rise in the number of high‐affinity binding sites (0.33 ± 0.04 and 0.63 ± 0.07 pmol/mg protein at 24 and 48 h, respectively), with no change in their affinity (1.34 and 1.42 × 10−10 mol/L). Affinity labeling of 125I‐EGF in cultured trophoblast cells followed by SDS‐PAGE and autoradiography revealed a band of 175 KDa corresponding to EGFR, the intensity of which increased with the time in culture. EGF‐dependent phosphorylation of membrane proteins from cultured trophoblast cells revealed major phosphorylated proteins of 170 KDa (EGFR) and 35 KDa, which were both increased at 48 h, indicating a rise in EGFR‐kinase activity during syncytium formation. Northern blot analysis of EGFR‐mRNA, followed by hybridization with a 32P‐cDNA probe for EGFR, revealed an increase in EGFR gene expression in syncytiotrophoblasts, as compared to cytotrophoblasts. Thus, the increase in bioactive EGFR observed during the differentiation of trophoblast cells was due to an increase in their synthesis. Cultured trophoblast cells are therefore a good model of spontaneous up‐regulation of EGFR expression with cell differentiation. © 1993 Wiley‐Liss, Inc.
Content of nonhistone protein in nuclei after hyperthermic treatment
Authors: Chu G. L. , Ross G. , Wong R. S. L. , Warters R. , Dewey W. C. 
Published: February 2005

AbstractWhen nuclei were isolated from Chinese hamster ovary cells after being heated, there was a large increase in the amount of 3H‐tryptophan labeled nonhistone protein in the nucleus relative to the whole cell. After 15 min or 30 min of heating at 45.5°C, the nuclear nonhistone protein content increased by 1.6 or 1.8, respectively. In contrast, when the nuclear nonhistone protein content was determined in the intact cell by using autoradiography to quantify 3H‐tryptophan labeled protein in the nucleus and cytoplasm in sections of fixed cells, the nuclear nonhistone protein content increased by only 1.14 or 1.28 for 15 or 30 min at 45.5°C, respectively. Therefore, heat does not induce a massive movement of cytoplasmic protein into the nucleus. © 1993 Wiley‐Liss, Inc.
Polyamine regulation of Na+/glucose symporter expression in LLC‐PK1 cells
Authors: Peng Hua , Lever Julia E. 
Published: February 2005

AbstractAddition of polyamines or their analogs to newly confluent LLC‐PK1 cells resulted in down‐regulation of Na+‐glucose transport (symport) activity. Polyamines prevented the induction of this symporter by the differentiation inducer hexamethylene bisacetamide (HMBA) but did not influence induction by the phosphodiesterase inhibitor 3‐isobutyl‐1‐methylxanthine (IBMX). Partial depletion of endogenous polyamines after addition of α ‐difluoromethylornithine (DFMO) resulted in a 4 to 5‐fold increase in symporter expression. Symporter induction by either HMBA or DFMO was inhibited by the protein kinase inhibitor H‐7 but H‐7 did not affect symporter induction by IBMX. Changes in symporter activity were accompanied by changes in levels of the 75 kD symporter subunit detected by Western blot. Cultures exposed to HMBA exhibited reduced levels of ornithine decarboxylase activity. Our results suggest that induction of symporter expression by HMBA may be mediated in part by its effects on polymine metabolism, and point to parallel roles of polyamines and cyclic AMP in regulating the expression of this physiologically important renal transport system. © 1993 Wiley‐Liss, Inc.
Structural reaction pattern of hepatocytes following exposure to hypotonicity
Authors: Pfaller Walter , Willinger Christian , Stoll Barbara , Hallbrucker Christian , Lang Florian , Häussinger Dieter 
Published: February 2005

AbstractIsolated rat hepatocytes were exposed to hypotonic media (225 mosmol/l) for 5 and 15 min and processed for a quantitative electron microscopic stereologic analysis. Within 5 min of hypotonicity, the hepatocyte volume increased by 25% and thereatter displayed a volume regulatory decrease leading to mean cellular volume, which was 16% above that of controls. Stereologic analysis of the major subcellular compartment, the cytosol, showed an identical change as the whole cell. In contrast to that, the mitochondrial compartment increased in volume by 30% within the first 5 min of exposure and returned by regulatory volume decrease back to values of the isotonic controls after 15 min of hypotonicity. In contrast, hypotonicity (220 mosmol/l)‐stimulation of flux through mitochondrial glutaminase and the glycine cleavage enzyme complex, as assessed by 14CO2 production from [1‐14C]glutamine or [1‐14C]glycine in isolated perfused rat liver persisted throughout a 15‐min period of hypotonic exposure. Thus hypotonicity‐induced alterations of mitochondrial metabolism apparently do not parallel the time course of mitochondrial volume changes. This suggests that persistent mitochondrial swelling is not required for functional alterations, but that the latter may be triggered by the initial swelling of mitochondria. Hypotonic exposure did not alter the nuclear volume of isolated hepatocytes. Cell membrane surface nearly doubled after 5 min of hypotonic exposure, but returned within 15 min of exposure to values observed in normotonic media. This may reflect the participation of exocytosis in hepatocyte volume regulation. © 1993 Wiley‐Liss, Inc.
Regulation of matrix synthesis rates by the ionic and osmotic environment of articular chondrocytes
Authors: Urban J. P. G. , Hall A. C. , Gehl K. A. 
Published: February 2005

AbstractChondrocytes in cartilage are embedded in a matrix containing a high concentration of proteoglycans and hence of fixed negative charges. Their extracellular ionic environment is thus different from that of most cells, with extracellular Na+ being 250–350 mM and extracellular osmolality 350–450 mOsm. When chondrocytes are isolated from the matrix and incubated in standard culture medium (DMEM; osmolality 250–280 mOsm), their extracellular environment changes sharply. We incubated isolated bovine articular chondrocytes and cartilage slices in DMEM whose osmolity was altered over the range 250–450 mOsm by Na+ or sucrose addition. 35S‐sulphate and 3H‐proline incorporation rates were at a maximum when the extracellular osmolality was 350–400 mOsm for both freshly isolated chondrocytes and for chondrocytes in cartilage. The incorporation rate per cell of isolated chondrocytes was only 10% that of chondrocytes in situ both 4 and 24 hours after isolation. For freshly isolated chondrocytes, the rate increased 30–50% in DMEM to which NaCl or sucrose had been added to the increase osmolality. In chondrocytes incubated overnight in DMEM, the rate was greatest in DMEM of normal osmolality and fell from the maximum in proportion to the change in osmolality. The effects of surcrose addition on incorporation rates were similar but not identical to those of Na+ addition. Changes in cell volume might be linked to changes in synthesis rates since the cell volume of chondrocytes (measured by Coulter‐counter) increased 30–40% when the cells are removed from their in situ environment into DMEM. Synthesis rates can thus be partly regulated by changes in extracellular osmolality, which in cartilage is controlled by proteoglycan concentration. This provides a mechanism by which the chondrocytes can rapidly respond to changes in extracellular matrix composition. © 1993 Wiley‐Liss, Inc.
Effect of cell age and phenylhydrazine on the cation transport properties of rabbit erythrocytes
Authors: Brugnara Carlo , De Franceschi Lucia 
Published: February 2005

AbstractWe studied the effect of cell age on the cation transport systems of rabbit erythrocytes by increasing the proportion of circulating young erythrocytes with either repeated bleeding or with phenylhydrazine (PHZ) treatment. We found that when the reticulocyte content of rabbit blood is increased by bleeding (from 1 to 40–50% of the circulating red cells), the response of the various transport pathways differs. The largest increase (fivefold) was found in the activity of K‐CI contransport which peaked 3 days after the last bleeding. The Na‐K pump activity peaked at a similar time, but the % increase was twofold less than the K‐CI contransport. There was very small increase in the activity of the Na‐Li exchange, whereas the Na‐H exchange reached peak values 10 days after the last bleeding (twofold increase), when activities of K‐Cl contransport and Na‐K pump had returned to almost normal levels. In vivo PHZ treatment resulted in anemia and marked reticulocytosis (80–90% of circulating cells). Transport rates were markedly increased (Na‐K pump 9.6‐fold, Na‐H exchange 6.8‐fold, Na‐Li exchange 2.75‐fold; K‐CI contransport: 10–20‐fold). When blood from PHZ‐treated rabbits was incubated in vitro for 24–48 hour, red cell volume and K content decreased. This process was associated with a 70% reduction in the activity of the K‐CI contransport after 24 hours and a 90% reduction after 48 hours. The activity of the other systems also declined and approached baseline values after 48 hours. Loss of transport activity was not affected by 10 μM E‐64, whereas 10 mM methylamine reduced the inactivation of the Na‐H exchange and of the Na‐Li exchange. PHZ treatment of rabbit red cells in vitro resulted in marked increase of the K‐CI contransport and inhibition of Na‐K pump, Na‐H exchange, and Na‐Li exchange. These effects were abolished by DTT, with the exception of the Na‐K pump inhibition, which was DTT insensitive. Thus both cell age and oxidative damage are important determinants of cation transport in rabbit red cells. © 1993 Wiley‐Liss, Inc.
Osteoblastic gene expression during adipogenesis in hematopoietic supporting murine bone marrow stromal cells
Authors: Dorheim Marie‐Annette , Sullivan Mary , Dandapani Viji , Wu Xiying , Hudson Jane , Segarini Patricia R. , Rosen David M. , Aulthouse Amy L. , Gimble Jeffrey M. 
Published: February 2005

AbstractA growing body of data suggests that the bone marrow stroma contains a population of pluripotent cells capable of differentiating into adipocytes, osteoblasts, and lymphohematopoietic supporting cells. In this work, the murine stromal cell lines BMS2 and +/+ 2.4 have been examined as preadipocytes and adipocytes for evidence of osteoblastic gene expression. Adipocyte differentiation has been quantitated using fluorescence activated cell sorting. Within 7–10 days of adipocyte induction by treatment with glucocorticoids, indomethacin, and methylisobutylxanthine, between 40% to 50% of the cells contain lipid vacuoles and exhibit a characteristic adipocyte morphology. Based on immunocytochemistry, both the adipocytes and preadipocytes express a number of osteoblastic markers; these include alkaline phosphatase, osteopontin, collagen (I, III), bone sialoprotein II, and fibronectin. Based on biochemical assays, the level of alkaline phosphatase expression is not significantly different between preadipocyte and adipocyte cells. However, unlike rat cell lines, dexamethasone exposure causes a dose‐dependent decrease in enzyme activity. The steady‐state mRNA levels of the osteoblast associated genes varies during the process of adiopogenesis. The relative level of collagen I and collagen III mRNA is lower in adipocyte‐induced cells when compared to the uninduced controls. Osteocalcin mRNA is detected in preadipocytes but absent in adipocytes. These data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated. © 1993 Wiley‐Liss, Inc.
Angiotensin II‐induced vascular smooth muscle cell hypertrophy: PDGF A‐chain mediates the increase in cell size
Authors: Berk Bradford C. , Rao Gadiparthi N. 
Published: February 2005

AbstractWe report here that angiotensin II‐mediated hypertrophy of vascular smooth muscle cells (VSMC) exhibits PDGF A‐chain‐and ‐pathways. Secretion of PDGF A‐chain is required for the increase in cell size, but not for the increase in protein synthesis. Angiotensin II stimulates a hypertrophic growth response in VSMC characterized by increases in cell size and protein synthesis, but not cell number. Because angiotensin II‐stimulated VSMC hypertrophy has been associated with increased PDGF A‐chain expression, we studied its role in the hypertrophic response by inhibiting PDGF A‐chain expression with hydrocortisone or anti‐PDGF antibody. Hydrocortisone (1 μM for 48 h) inhibited basal protein synthesis by 47%, but angiotensin II‐stimulated protein synthesis was enhanced (111% increase after hydrocortisone treatment vs. 25% increase in control). In contrast, hypertrophy, as measured by cell size, was completely inhibited. Although hydrocortisone had no effect on early growth signals stimulated by angiotensin II (e.g., activation of protein kinase C, stimulation of Na+/H+ exchange, and c‐fos and c‐myc expression), it significantly decreased angiotensin II‐stimulated secretion of PDGF‐like material into the medium from 0.4 to 0.1 ng/ml/24 h (p < 0.01). However, the time course for PDGF secretion (maximal at 16–24 h) was significantly slower than the time course for angiotensin II‐stimulated protein synthesis (maximal at 4–12 h). To block the action of PDGF A‐chain selectively, VSMC were treated with anti‐PDGF A‐chain antibody. The antibody completely inhibited the angiotensin II‐stimulated increase in cell size, but it had no significant effect on protein synthesis at early times (<8 h). These findings demonstrate two pathways involved in angiotensin II‐stimulated VSMC hypertrophy: an increase in cell size dependent on PDGF A‐chain and an increase in protein synthesis independent of PDGF A‐chain. © 1993 Wiley‐Liss, Inc.
Platelet‐activating factor secreted by DDAVP‐treated monocytes mediates von willebrand factor release from endothelial cells
Authors: Hashemi S. , Palmer D. S. , Aye M. T. , Ganz P. R. 
Published: February 2005

AbstractWe have previously shown that although DDAVP (1‐deamino‐8‐D‐arginine vasopressin), a synthetic analogue of the natural hormone arginine vasopressin, does not directly promote release of vWf from human umbilical vein endothelial cells (ECs), enhanced release does occur when ECs were exposed to either monocytes or to supernatants recovered from DDAVP‐treated monocytes. In the present study, we have found that exposure of monocytes to DDAVP did not increase secretion of interleukins (IL)‐1β, IL‐6, IL‐8, tumor necrosis factor (TNF‐α), growth factors G‐CSF (granulocyte‐), GM‐CSF (granulocyte, monocyte‐colony stimulating factor), prostaglandins (PG) E2, PGF2α, or PGI2 or purine nucleotides such as ATP and ADP. However, increased levels of platelet‐activating factor (PAF) were secreted by DDAVP‐treated monocytes in a time‐ and dose‐dependent manner that positively correlated with the enhancement in vWf release from ECs. Moreover, this effect could also be elicited when lipid extracts of these supernatants or purified PAF were added directly to ECs. This response could be inhibited with (±)‐trans‐2,5‐Bis(3,4,5‐trimethoxyphenyl)‐1,3‐dioxolane, a specific PAF receptor antagonist, when the ECs were exposed to supernatants from DDAVP‐treated monocytes or to pure PAF. The present data indicate that enhanced secretion of PAF from monocytes is one mechanism whereby DDAVP can provoke release of vWf from ECs. © 1993 Wiley‐Liss, Inc.
Low oxygen stimulates proliferation of fibroblasts seeded as single cells
Authors: Falanga Vincent , Kirsner Robert S. 
Published: February 2005

AbstractIn standard tissue culture conditions (20% oxygen), single human dermal fibroblasts (one cell per well) do not proliferate. We now report that low oxygen tension is a potent stimulus for the proliferation and expansion of human adult and neonatal dermal fibroblasts seeded as single cells. This preferential single‐cell proliferation in low oxygen is shown to be also a feature of human lung and dermal rodent fibroblasts, but not of human fibrosarcoma and immortalized 3T3 cells, which proliferate without difficulty in standard oxygen conditions. It is suggested that single‐cell proliferation and its dramatic stimulation in low oxygen may represent a fundamental biologic process with an opportunity to better understand mammalian cell growth regulation. © 1993 Wiley‐Liss, Inc.
Microscale autoradiographic method for the qualitative and quantitative analysis of apoptotic DNA fragmentation
Authors: Tilly Jonathan L. , Hsueh Aaron J. W. 
Published: February 2005

AbstractA method combining the advantages of electrophoretic DNA fractionation and autoradiography is described for the qualitative and quantitative analysis of internucleosomal DNA fragmentation that occurs during apoptosis, or “programmed cell death”. This procedure utilizes terminal transferase enzyme to uniformly add one molecule of [α 32P]‐to the 3′‐of DNA fragments. Following gel electrophoresis and autoradiographic analysis, the total amount of radiolabel incorporated into the low molecular weight DNA fraction can be quantitated and used to estimate the degree of apoptotic DNA fragmentation in any given sample. This method requires as little as 15 ng of total cellular DNA and increases the sensitivity of apoptotic DNA detection by at least 100‐fold over the widely used ethidium bromide staining method. The procedure should prove valuable for the analysis of apoptosis in minute quantities of tissues and cultured cells. © 1993 Wiley‐Liss, Inc.
Adhesiveness and proliferation of epithelial cells are differentially modulated by activation and inhibition of protein kinase C in a substratum‐dependent manner
Authors: Zhou You , Dziak Ewa , Opas Michal 
Published: February 2005

AbstractIn the present study, we have examined the regulation of attachment, onset of proliferation and the subsequent growth, in vitro, of chick retinal pigmented epithelial (RPE) cells as a function of the nature of the substratum and of either the activation or inhibition of protein kinase C (PKC). The RPE cells have an adhesive preference for protein carpets which contain laminin. This preference disappears gradually with time in culture. The adhesion of RPE cells to fibronectin is shown to be a receptor‐mediated process which involves the RGD recognition signal. This study also demonstrates that a PKC activator, 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA), affects RPE cell adhesion in a substratum‐dependent manner. Exposure of RPE cells to TPA lowers the cell attachment efficacy to ECM protein substrata but does not affect cell attachment to plastic. The onset of cell proliferation is accelerated by TPA on all of the substrata tested. The minimal duration of an effective TPA pulse exerting a long‐lasting influence on RPE cell proliferation is between 1.5 and 3.5 hr. Stimulation of cell proliferation by TPA in long‐term cultures is independent of the nature of the growth substratum. The acceleration of the onset of cell proliferation by TPA is sensitive to 1‐(5‐isoquinolinesulfonyl)‐2‐methylpiperazine (H7), an inhibitor of conventional PKC, and thus appears to be dependent on the activation of conventional PKC. H7 also affects cell‐cell contacts, causing an alteration in the shape (“squaring”) of RPE cells packed into large colonies. Conversely, the effects of TPA on both the attachment and the long‐term proliferation of RPE cells are not dependent a conventional PKC isotype, since H7 cannot abolish the influence of TPA on either process. We conclude that the effect of TPA on long‐term proliferation of RPE cells is either dependent on a novel PKC isotype or independent of PKC. © 1993 Wiley‐Liss, Inc.
Synergistic effects of cytokine and hyperthermia on cytotoxicity in HT‐29 cells are not mediated by alteration of induced protein levels
Authors: Lee Yong J. , Hou Zizheng , Curetty Lindali , Cho Joong M. , Corry Peter M. 
Published: February 2005

AbstractIn this study, we investigated the mechanism of synergistic effects of cytokine and hyperthermia on cytotoxicity in HT‐29. When cells were heated at 42°C in the presence of recombinant human tumor necrosis factor (rhTNF‐α), recombinant interferon‐gamma (rhIFN‐γ), or in a combination of both, a synergistic increase in the cytotoxic effects of the respective drugs was observed. We hypothesized that alteration of cytokine or heat‐induced polypeptides synthesis was responsible for a synergistic interaction between heat and cytokine.Five heat shock proteins (HSPs, Mr 110,000, 100,000, 90,000, 70,000, and 28,000) were preferentially synthesized during chronic heating at 42°C. In contrast, the synthesis of two proteins (Mr 60,000 and 29,000) was induced by treatment with rhIFN‐γ (1,000 U/ml). Although the combination of chronic hyperthermia (42°C) with TNF‐α, IFN‐γ, or TNF‐α + IFN‐γ increased cytotoxicity, alteration/induction of polypeptides was not correlated with the synergistical cytotoxic effects of cytokine and heat. Thus, the synergistic effects of cytokine and hyperthermia are not mediated through an induction of polypeptides. © 1993 Wiley‐Liss, Inc.