bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of insulin receptors on the insulin‐independent variant 1246‐3A cell line
Authors: Gazzano Helene , Serrero Ginette 
Published: February 2005

Abstract1246‐3A cell line is an insulin‐independent variant isolated from the adipogenic cell line 1246 which can proliferate in the absence of insulin, has lost the ability to differentiate, and secretes an insulin‐related factor called IRF similar to pancreatic insulin and different from IGFs. In contrast, the parent adipogenic cell line 1246 is dependent on the presence of insulin to proliferate and differentiate in defined medium. In the present paper, we examined if the loss of response to insulin observed for 1246‐3A cells was accompanied by alterations in the insulin receptor properties. Insulin binding and tyrosine kinase activity of insulin receptors isolated from 1246‐3A cells and from the parent cell line 1246 were measured; 125I‐insulin binding to intact cells was 75% lower for the 1246‐3A cells than for the 1246 cells. This was due to a decrease in receptor number without major change in receptor affinity. However, when the cells were solubilized in 1% Triton X‐100 and the insulin receptor was partially purified by chromatography on wheat germ agglutinin‐agarose, a similar pattern of binding was observed for both cell lines. Down regulation of insulin receptors by insulin occurred in a dose‐dependent fashion, which was similar for both cell lines. Phosphorylation experiments were performed by incubation of the partially purified insulin receptor with insulin and [γ‐32P]ATP. They indicated that insulin stimulated phosphorylation of the 95‐kDa molecular weight β subunit of the receptor, in a similar fashion for both cell types. These data suggest that the insulin‐independent cell line 1246‐3A does not possess a specific defect in the insulin receptor which alters both its binding and autophosphorylation properties and that the loss of response to insulin can be attributed to the fact the 1246‐3A cells secrete IRF which bind to cell surface receptors and stimulate their proliferation.
Similarities in glycosylation and transport between the secreted and plasma membrane forms of the epidermal growth factor receptor in A‐431 cells
Authors: Soderquist Ann Mangelsdorf , Stoscheck Christa , Carpenter Graham 
Published: February 2005

AbstractWe have studied the synthesis and oligosaccharide processing of the 110,000 dalton form of the epidermal growth factor (EGF) receptor that is secreted into the medium of A‐431 cells. Its 90,000 dalton precursor is soluble within the lumen of intracellular membrane vesicles shortly after synthesis, indicating that it lacks a membrane anchor. Analysis of labeled glycopeptides reveals that the glycosylation of the 110,000 dalton, secreted receptor is very similar to that of the 170,000 dalton, plasma membrane receptor. Based on Concanavalin A‐Sepharose elution profiles of its glycopeptides, the secreted receptor has both complex and high‐mannose N‐linked oligosaccharides. Also, like the plasma membrane receptor, the secreted receptor contains N‐acetylgalactosamine residues in its complex chains. Not only are major features of oligosaccharide processing of the soluble and membrane‐bound forms of the receptors similar, but the kinetics of transport to the cell exterior is the same for each. These data indicate that the glycosylation pattern and kinetics of cellular transport of the EGF receptor are determined by factors other than the sequence of its cytoplasmic and transmembrane domains.
Inhibition of macrophage activation by isoquinolinesulfonamides, phenothiazines, and a napthalenesulfonamide
Authors: Holian Andrij , Jordan Mark K. , Nguyen Hanh V. , Devenyi Zoltan J. 
Published: February 2005

AbstractThe influence of isoquinolinesulfonamides (H‐7 and H‐8), phenothiazines(trifluoperazine and fluphenazine), and a naphthalenesulfonamide (N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulfonamide (W‐7)) on stimulated superoxide anion production and phosphatidyl inositol (PI) cycle activity was investigated in the guinea pig alveolar macrophage. All five drugs were able to inhibit superoxide anion production stimulated by n‐formyl‐nel‐leu‐phe (FNLP), leukotriene B4 (LTB4), and phorbol‐12,13‐dibutyrate (PDB). The order of potency was trifluoperazine ≥ fluphenzine > H‐7 = W‐7 > H‐8. The dose response curves could be shifted to less efficacy by increasing extracellular calcium. By itself, W‐7 markedly stimulated 45Ca+2 efflux, efflux, fluphenazine and trifluoperazine slightly stimulated 45Ca+2 efflux from macrophages preloaded with 45Ca+2. Consistent with these results, W‐7 markedly stimulated PI cycle activity, fluphenazine and trifluoperazine slightly stimulated PI cycle activity, while H‐7 and H‐8 had no significant effects on PI cycle activity. In addition, W‐7 by itself was able to stimulate a weak and short‐lived “burst” of superoxide anion production. In order to evaluate whether a site of action of the inhibitors was at protein kinase C and whether protein kinase C was involved in terminating the normally short‐lived FNLP‐ and LTB4‐stimulated macrophage activation, fluphenazine and H‐7 were used to evaluate the duration of FNLP‐ and LTB4‐stimulated PI cycle activity, at concentrations of the inhibitors that significantly blocked stimulated superoxide anion production. In all cases, FNLP and LTB4 still stimulated PI cycle activity, which still terminated even though protein kinase C was inhibited. These results suggest that all five drugs block protein kinase C, but H‐7 was the most specific in its action at protein kinase C, while the phenothiazines and W‐7 have multiple sites of action. In addition, these results suggest that protein kinase C may not function to cause the termination of FNLP‐ and LTB4‐stimulated PI cycle activity and subsequent superoxide anion production.
Stimulation by thyroid hormone of phosphate transport in primary cultured renal cells
Authors: Noronha‐Blob Lalita , Lowe Valerie , Sacktor Bertram 
Published: February 2005

AbstractThe regulation by thyroid hormone of phosphate transport in primary cultured chick renal cells was examined. The more physiologically active L‐analogs of triiodothyronine and thyroxine, but not the D‐analogs of the hormones, stimulated the Na+ ‐dependent phosphate uptake system. Na+ ‐independent phosphate uptake and Na+ ‐dependent uptakes of α‐methylglucoside and L‐proline were unaffected. The increase in Na+ ‐dependent phosphate uptake was concentration dependent, exhibited an induction period, and was blocked by inhibitors of RNA and protein synthesis. The stimulation of phosphate uptake by triiodothyronine was due to an increased Vmax rather than to an altered affinity for phosphate. These findings demonstrate that thyroid hormone acts directly on renal cells to modulate phosphate transport and suggest that the renal cell system may serve as a model to examine the mechanism by which thyroid hormone controls gene expression and regulates plasma membrane transport function.
Intercellular adhesion molecule‐1 (ICAM‐1) is involved in the cytolytic T lymphocyte interaction with a human synovial cell line
Authors: Mentzer Steven J. , Rothlein Robert , Springer Timothy A. , Faller Douglas V. 
Published: February 2005

AbstractThe cell surface molecules involved in the human cytolytic T lymphocyte (CTL)‐synovial cell interaction may play an important role in T cell interactions with connective tissue mesenchymal cells. To examine the molecular basis for the CTL‐synovial cell interaction, we immortalized synovial cell explants to establish the cell line SYN.SPP. The SYN.SPP cell line was compared to the established B lymphoblastoid cell line JY. Cell surface immunofluorescence demonstrated significantly different levels of the immunologically relevant cell surface molecules ICAM‐1 and LFA‐3. Both cell lines were used to stimulate CTL precursors. After several months in culture, CTL lines stimulated by the SYN.SPP and JY cell lines demonstrated HLA class I‐directed cytolytic activity. The cell surface molecules utilized by the anti‐SYN.SPP and anti‐JY CTL lines were identified by monoclonal antibody (MAb) inhibition. MAb recognizing the CTL cell surface molecules CD3, CD8 and LFA‐1 (CD11a) significantly inhibited CTL‐mediated lysis of both target cells. An interesting observation was that the anti‐SYN.SPP CTL line appeared to utilize the ICAM‐1 and not the LFA‐3 target cell molecule. In contrast, the anti‐Y CTL line utilized the LFA‐3 and not the ICAM‐1 membrane molecule. These results indicate that CTL interactions with connective tissue mesenchymal cells may be regulated by a unique pattern of antigen nonspecific cell‐cell interaction molecules.
Elevation of angiotensin converting enzyme by 3‐isobutyl‐1‐methylxanthine in cultured endothelial cells: A possible role for calmodulin
Authors: Dasarathy Yamuna , Fanburg Barry L. 
Published: February 2005

AbstractIncubation of cultured bovine pulmonary artery endothelial cells with 200 μM of 3‐isobutyl‐1‐methylxanthine (IBMX) for 24 hr produced a five‐to tenfold increase in cellular angiotensin converting enzyme activity (ACE) above that of untreated control cells. A lesser increase was observed in medium ACE. Other methylxanthines produced a similar, but less marked, effect. The elevation of ACE seemed to require de novo protein synthesis since it was reduced by 0.1 μ/ml cycloheximide. Elevation of cellular cAMP was detected at 30 min after introduction of IBMX, then rapidly returned to control levels at 1 hour, while elevation in cellular ACE at 24 hr required contact with IBMX for at least 2 hr. Hence, the transient elevation in cAMP is unlikely to be the cause of the elevation of ACE. Phorbol ester and synthetic diacyl glycerol OAG, activtors of protein kinase C, did not elevate ACE. Indomethacin, at a concentration known to inhibit cycloxygenase activity, had no effect on the elevation of ACE. The elevation of ACE by IBMX was not affected by the calcium channel blocker verapamil or the calcium chelator EGTA. In contrast, the effect of IBMX was totally abolished by the calmodulin inhibitors trifluoperazine and calmidazolium. The data show that IBMX elevates endothelial cell ACE and suggest that the elevation is mediated by a calcium‐calmodulin complex. The studies demonstrate a novel effect of methylxanthines on endothelial cells in culture.
Influence of the extracellular matrix on the proliferative response of human skin fibroblasts to serum and purified platelet‐derived growth factor
Authors: Rhudy Roberta W. , McPherson John M. 
Published: February 2005

AbstractThe culture of adult human skin fibroblasts on reconstituted bovine type I fibrillar collagen gels, ranging in concentration from 2.5–35.0 mg/ml, results in a reduction in proliferation rate by 40%–60% as measured by (3H) thymidine incorporation. The suppressive effect was noted when cells were cultured in both human and bovine serum. Drying the gels into thin films abolishes the suppressive effect of the fibrillar collagen on cell proliferation. Cell attachment studies showed that differences in the proliferation rate of cells on the various substrata were not simply due to differences in initial attachment. Studies with purified platelet‐derived growth factor (PDGF) demonstrated that the reduced responsiveness of cells to this factor, when cultured on collagen gels as compared to plastic, was largely responsible for the reduced proliferative activity of the cells when cultured in the presence of serum. The reduced proliferative activity of fibroblasts in response to PDGF, when cultured on collagen gels, was confirmed by total DNA determination. It was shown that the reduced responsiveness of cells to PDGF was not simply because the factor bound to the fibrillar collagen gel or was inaccessible to the cells. The data indicate that the reduced proliferation rate of fibroblasts cultured on collagen gels is a direct result of the influence of the extracellular matrix on the cells' ability to respond to a soluble mitogenic mediator.
Effect of hypo‐osmotic incubation on membrane recycling
Authors: Novak Jeanne M. , Ward Diane McVey , Buys Saundra S. , Kaplan Jerry 
Published: February 2005

AbstractIncubation of alveolar macrophage in hypo‐osmotic media causes a time‐and temperature‐dependent increase in the number of surface receptors for three different ligands. Exposure of cell to solutions of 210 mOsM or less, at 37°C but not at 0°C, resulted in an increase in the number of surface receptors for diferric transferrin, alpha‐macroglobulin‐protease complexes, and mannose‐terminated glycoproteins. Upon media dilution at 37°C, surface receptor number reached a maximum within 5 min and returned to near‐normal values by 30 min. The increase in surface receptor number was the result of a decrease in the rate of internalization of receptors, either occupied or unoccupied. The rate of receptor exteriorization was unaltered by hypo‐osmotic incubation of cells. The rate of fluid‐phase pinocytosis was also inhibited upon incubation in hypo‐osmotic solution. In experiments in which both receptor‐mediated endocytosis and fluid phase pinocytosis were measured on the same samples, inhibition of both processes occurred with the same kinetics and to a similar extent. The rate of receptor‐mediated endocytosis recovered to normal rates after 60 min in hypo‐osmotic solutions, whereas the rate of fluid phase pinocytosis did not recover to the same extent.
Identification of neutrophil alkaline phosphatase‐inducing factor in cystic fluid of a human squamous cell carcinoma as granulocyte colony‐stimulating factor
Authors: Sato Noriharu , Asano Shigetaka , Koeffler H. Phillip , Yoshida Satoru , Takaku Fumimaro , Takatani Osamu 
Published: February 2005

AbstractWe have previously shown that a factor termed neutrophil alkaline phosphatase‐inducing factor (NAP‐IF) has the capacity to induce neutrophil alkaline phosphatase (NAP) in postmitotic granulocytes (PMGs). This factor has characteristics similar to those of granulocyte colony‐stimulating factor (G‐CSF), suggesting that the two factors assayed by different methods may be attributable to an identical macromolecule. In a preliminary experiment, we showed that purified natural G‐CSF (nG‐CSF) could induce NAP in vitro in the presence of 10% (v/v) fetal calf serum (FCS). In this study, purified human nG‐CSF and recombinant G‐CSF (rG‐CSF) induced NAP in granulocytes from both normal individuals and patients with chronic myelogenous leukemia in a dose‐dependent fashion in serum‐free and serum‐containing culture conditions. The induction of NAP by G‐CSF was detectable at 0.4 ng/ml and became maximal between 10 and 20 ng/ml. Anti‐G‐CSF serum incubated with either NAP‐IF or rG‐CSF inhibited induction of NAP. Morphological examinations revealed that granulocytes cultured with G‐CSF were more mature than those cultured without G‐CSF, indicating that G‐CSF promoted maturation of granulocytes in parallel with NAP induction. These results indicate that NAP‐IF in the cystic fluid of a human squamous cell carcinoma is identical to G‐CSF and that induction of NAP by G‐CSF is really a reflection of cell maturation promoted by G‐CSF.
Pyrimido‐pyrimidine modulation of EGF growth‐promoting activity and p21ras expression in rat mammary adenocarcinoma cells
Authors: Lichtner Rosemarie B. , Gallick Gary E. , Nicolson Garth L. 
Published: February 2005

AbstractRA 233, a pyrimido‐pyrimidine analogue developed originally as an antiplatelet agent, has reduced the incidence of tumor metastases in clinical trials. However, in animal tumor models antimetastatic therapy using RA 233 has been inconsistent. We therefore tested RA 233 for additional effects, such as its direct action on tumor cells. Using the rat 13726NF mammary adenocarcinoma tumor system, low, nontoxic concentrations of RA 233 had pleiotropic and differential effects on two 13762NF tumor cell clones. The growth of MTC cells (low spontaneous metastatic potential) was not affected by low concentrations of RA 233 (50 m̈M) or epidermal growth factor (EGF) (up to 10 ng/ml) for 3 days in 0.5–10% fetal bovine serum. In contrast, MTLn3 (high spontaneous metastatic potential) cell cultures maintained for 3 days in low (0.5–1%) serum in the presence of 1.25–10 ng/ml EGF doubled in cell numbers compared with control cultures, and addition of 50 m̈M RA 233 abrogated the growth‐stimulatory effect of EGF. The inhibitory effect of RA 233 on MTLn3 cells was dose dependent and not due to cell toxicity as determined by cell viability, cell growth, and colony formation properties after drug removal. In addition, incubation of MTLn3 cell with 50 m̈M RA 233 resulted in an increase of p21ras protein expression, whereas there was no effect on the level of p21ras in identically treated MTC cells or when either clone was treated with 10 ng/ml EGF. The results suggest that among the heterogeneous effects of RA 233 on tumor cells, modulation of growth factor responses and regulatory molecules may be important.
Relative contribution of the leukocyte molecules MO1, LFA‐1, and p150,95 (LeuM5) in adhesion of granulocytes and monocytes to vascular endothelium is tissue‐ and stimulus‐specific
Authors: Arnaout M. Amin , Lanier Lewis L. , Faller Douglas V. 
Published: February 2005

AbstractAdhesion of human monocytes and granulocytes to vascular endothelium plays an important role in migration of these cells to inflammatory sites in tissues. A family of three human leukocyte heterodimeric surface molecules named Mo1, LFA‐1, and p150,95 (LeuM5) has been shown to mediate leukocyte adhesion to confluent monolayers of human umbilical vein endothelial cells (HUVE). The relative contribution of each of the three molecules in leukocyte endothelial adhesion was studied using a variety of stimuli. Purified human granulocytes and monocytes were radiolabelled and incubated with HUVE for 45 minutes in a 37°C humidified 5% CO2 incubator in the presence or absence of subunit‐specific monoclonal antibodies (MAbs). Adhesion was assessed by quantitation of endothelial cell‐associated radioactivity and confirmed by microscopic evaluation. MAbs directed against the alpha subunit of LFA‐1 as well as to the beta subunit common to all three antigens significantly inhibited unstimulated monocyte adhesion to HUVE. Small but significant inhibition was also observed using MAbs directed against Mo1a and p150. Phorbol myristate acetate (PMA)‐induced grranulocyte adhesion to HUVE was significantly inhibited by anti‐Mo1a and anti‐beta, but not by anti‐LFA‐1a or anti‐p150. When HUVE were prestimulated by recombinant IL‐1, a different pattern of antigen utilization by granulocytes was observed. MAbs directed against each of the three alpha subunits as well as the common beta subunit all inhibited granulocyte adhesion to HUVE. Furthermore the effect of the three anti‐alpha subunit MAbs on granulocyte‐HUVE adhesion was additive. These studies show that relative contribution of Mo1, LFA‐1, and p150,95 to leukocyte endothelial adhesion varies depending on the cell type and the stimulus used. These studies also reveal a novel role for p150,95 in promoting monocyte and granulocyte adhesion to HUVE.
Cell‐to‐cell heterogeneity in the expression of carbohydrate‐based epitopes of a mucin‐type glycoprotein on the surface of human mammary carcinoma cells
Authors: Moss Lenny , Greenwalt Dale , Cullen Betsey , Dinh Nina , Ranken Ray , Parry Gordon 
Published: February 2005

AbstractA large, O‐linked glycoprotein, termed PAS‐O, is a major differentiation antigen on the surface of normal lactating breast epithelia and is also found on the surface of many mammary tumors and mammary carcinoma cell lines. A characteristic feature of populations of tumor cells that express PAS‐O is the cell‐to‐cell heterogeneity with respect to the presence or absence of the molecule. In this study, we used the human mammary carcinoma line 734B and a set of six monoclonal antibodies reactive with PAS‐O to study the basis of this heterogeneity. Extensive Western blot analysis of antibody binding to PAS‐O in milk fat globule membranes and in skim milk revealed that the antibodies all recognized different epitopes of PAS‐O. Moreover, the epitopes were destroyed by periodic acid oxidation, demonstrating their oligosaccharide basis. All six monoclonal antibodies stained the 734B cells heterogeneously. In addition, five clones derived from the parent 734B population also exhibited heterogeneity in the expression of each of the epitopes. An analysis of staining of the 734B clones revealed that, in some cases, certain cells within the cloned population stained with one monoclonal antibody but not with another antibody. Significantly, though, when the 734B cells were treated with neuraminidase prior to antibody staining, most of the heterogeneity was eliminated, and all but one of the monoclonal antibodies stained 90–100% of the cells. This increase in cell staining was matched by an increase in PAS‐O staining on Western blots. We conclude that heterogeneity in PAS‐O expression on 734B cells is due partly to masking of epitopes by sialic acid and a variation (on a cell‐to‐cell basis) in the extent of PAS‐O sialylation.
Effect of continuous heat stress on cell growth and protein synthesis in Aedes albopictus
Authors: da Gloria da Costa Carvalho Maria , Freitas Marcia Soares 
Published: February 2005

AbstractAedes albopictus (clone C6/36) cells, which normally grow at 28°C, were maintained at a supraoptimal temperature of 37°C. The effect of continuous heat stress (37°C) on cell growth was analyzed as were the modifications occurring with protein synthesis during short‐ and long‐term heat stress. We observed that cells in lag or exponential growth phase, present inhibition of cell growth, and cells in the lag phase showed more sensitivity to death than cells growing exponentially. During the first hour of exposing the cells to 37°C, they synthesized two heat shock proteins (hsps) of 82 kd and 70 kd, respectively, concomitant with inhibition of normally produced proteins at control temperature (28°C). However, for incubations longer than 2 hr at 37°C, a shift to the normal pattern of protein synthesis occurred. During these transitions, two other hsps of 76 kd and 90 kd were synthesized. Pulse chase experiments showed that the 70‐kd hsp is stable at least for 18 hr, when the cells are returned to 28°C. However, if cells were incubated at 37°C, the 70‐kd hsp is stable for at least 48 hr. The 70‐kd hsp was localized in the cytoplasmic and in the nuclear compartment. OUr results indicate a possible role of hsp 70‐kd protein in the regulation of cell proliferation.
Glucose elevates ornithine decarboxylase expression in vero cells
Authors: Lundgren David W. , Prokay Sandra L. 
Published: February 2005

AbstractThe addition to Earle's balanced salt solution (EBSS) of amino acids that are transported by a Na+‐dependent cotransport system was not required by Vero cells for ornithine decarboxylase (ODC:EC 4.1.1.17) amplification. Vero cell ODC activity was elevated tenfold above basal levels when confluent cells were incubated for 5 hr in EBSS alone. ODC activity increased as a function of the incubation time in EBSS and was not elevated above basal enzyme levels when cells were incubated in EBSS minus glucose. ODC expession increased as a function of the glucose concentration in EBSS, with 20 mM glucose producing a 90‐fold increase in ODC activity. ODC expression is more responsive to glucose in high‐density quiescent cultures than in low‐density growing cultures. Enhanced ODC expression by glucose depended on Na+ and K+ concentrations. The specific activity of ODC was also elevated above basal levels when mannose or fructose replaced glucose in EBSS. The addition of alanine or asparagine to EBSS enhanced ODC activity above levels obtained with EBSS containing standard (5.5 mM) glucose concentrations. In the absence of glucose, alanine was more effective than asparagine in enhancing ODC expression. These results suggest that the transport of amino acids is not an absolute requirement for Vero cell ODC expression and that ODC expression is linked to changes in cellular energetics and/or ion fluxes.