Search Results
Results 351 - 400 of 1586
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Fujieda M - - 1999
The effects of prostaglandin E(2) (PGE(2)) on the parameters for proliferation and differentiation were studied in calvarial osteoblast-like cells isolated from rats of various ages. In cells not treated with PGE(2), it was found that mineralized bone nodule (BN) formation, alkaline phosphatase (ALP) activity, and the incorporation rate of [(3)H]thymidine ...
Kumar A - - 1999
Beta-Amyloid (Abeta), a 39-43 residue peptide generated by splicing of the amyloid precursor protein (APP), is one of the major components of senile plaques which are the hallmark of Alzheimer's disease (AD); and therefore, a role of Abeta in neuronal degeneration has been proposed. The factors which regulate the levels ...
Toki S - - 1999
Results from previous studies suggested that chronic treatment of rats or C6 glioma cells with antidepressants augments the coupling between Gs and adenylyl cyclase. As these effects on C6 glioma cells are seen in the absence of presynaptic input, several antidepressant drugs may have a direct "postsynaptic" effect on their ...
Stamer W D - - 1999
PURPOSE: Fluid flow across various endothelia results in a variety of intracellular and extracellular adaptations. In the living eye, aqueous humor flows across the surface of endothelial cells on trabecular meshwork (TM) beams and in the juxtacanalicular tissue and through or between a continuous monolayer of endothelial cells that line ...
Medentsev A G - - 1999
Changes in respiratory activity and in the contents of adenine nucleotides (ATP, ADP, AMP) were studied in cells of the yeast Yarrowia lipolytica during the development of cyanide-resistant respiration. The transition of the yeast from the logarithmic to the stationary growth phase due to exhaustion of glucose was associated with ...
Hatse S - - 1999
N6-Cyclopropyl-PMEDAP (cPr-PMEDAP) is a novel derivative of the acyclic nucleoside phosphonate 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP). Its cytostatic activity was found to be 8- to 20-fold more pronounced than that of PMEDAP and equivalent to that of the guanine derivative 9-(2-phosphonylmethoxyethyl)guanine (PMEG) against a variety of tumor cell lines. Unlike PMEDAP, but like ...
Zhou L - - 1999
PURPOSE: To characterize cyclic nucleotide phosphodiesterase isozyme activities in human trabecular meshwork cells and primary cultures of porcine trabecular meshwork cells. METHODS: Radioimmunoassay of acetylated acid extracts was used to determine changes in cyclic adenosine monophosphate (cAMP) and cyclic quanosine monophosphate (cGMP) in human trabecular meshwork cells treated with phosphodiesterase ...
Kocsis J F - - 1999
Previous work with mammalian and frog adrenocortical tissue and cells indicates that prostaglandins (PGs) can directly stimulate corticosteroidogenesis. However, work with avian adrenal preparations is absent. Therefore, the present studies with isolated chicken (Gallus gallus domesticus) and turkey (Meleagris gallopavo) adrenal steroidogenic cells were conducted to determine whether PGs can ...
Aouani A - - 1999
The polar planar compound hexamethylene bisacetamide (HMBA) is an inducer of terminal differentiation which has been extensively studied in the murine erythroleukemia cells (MELC). We have tested this compound in normal porcine thyroid cells in primary culture where it either activates or inhibits the major tissue specific functions of these ...
Makino Y - - 1999
Sodium-L-ascorbate, L-ascorbic acid, D-isoascorbic acid, sodium 5,6-benzylidene-L-ascorbate and sodium-6-beta-O-galactosyl-L-ascorbate, which produce ascorbyl radicals during the oxidative degradation, also induced cytotoxicity against cultured human renal carcinoma (TC-1) and glioblastoma multiform tumor (T98G) cell lines. On the other hand, L-ascorbic acid 2-phosphate magnesium and L-ascorbic acid 2-sulfate dipotassium salt, which do not ...
Saltarelli D - - 1999
In granulosa cells, the luteinising hormone (LH) and the follicle-stimulating hormone (FSH) receptors are coupled to the adenylyl cyclase-cAMP pathway. We identified at least eight different G proteins belonging to three families--Gs, Gq, and Gi/o--in primary human granulosa-lutein cells. By exploring the function of Gi/o by time-lapse and digital-imaging microscopy ...
Goto T - - 1999
BACKGROUND: Intracellular cyclic adenosine monophosphate (AMP) level changes are thought to play an important role in inhibiting cell proliferation and inducing differentiation in several types of cells. It has been reported that cyclic AMP analogs induce terminal differentiation in human prostate cancer cells. Consequently, phosphodiesterase inhibitors may be useful in ...
Komarova S V - - 1999
In suspensions of washed human erythrocytes, adenosine added in a single dose to concentrations of 0.1-10.0 mmol/l suspension was deaminated at rates ranging from 10 to 50 mmol/l cells h. The sum of adenosine, inosine, and hypoxanthine concentrations in the suspension, as well as the intracellular concentration of ATP, remained ...
Grasso Y Z - - 1999
The stable transfectants of wild-type (W25) and mutant thyrotropin-receptor (TSH-R) allow detection of the bioactivities of TSH-R antibodies in Graves' patients. A mutant Chinese hamster ovary (CHO) cell line (Mc1+2) transfected with a chimeric construct, where residues 8 to 165 of the TSH-R are replaced with residues 10 to 166 ...
Parsley S - - 1999
The alpha2-adrenoceptor mediating inhibition of forskolin-stimulated cyclic AMP accumulation in human neuroblastoma SH-SY5Y cells was further characterized. The alpha2-adrenoceptor agonists, UK 14,304 (5-bromo-6-(2-imidazolin-2-ylamino)quinoxaline), oxymetazoline, guanfacine, (-)-noradrenaline and clonidine concentration-dependently decreased cyclic AMP accumulation in this cell line (Emax ca. 50% inhibition). Agonist pEC50 values ranged between 6.7 and 7.8. Clonidine ...
Liu J G - - 1999
AIM: To study the mechanism underlying the difference in physical dependence potential of morphine (Mor), methadone (Met), buprenorphine (Bup), etorphine (Eto), and dihydroetorphine (DHE). METHODS: Adenylate cyclase of NG108-15 cells were used for studying the effects of different opiates on cAMP second messenger system. RESULTS: Bup, DHE, and Eto were ...
Deleu S - - 1999
The regular doubling of cell mass, and therefore of cell protein content, is required for repetitive cell divisions. Preliminary observations have shown that in dog thyrocytes insulin induces protein accumulation but not DNA synthesis, while TSH does not increase protein accumulation but triggers DNA synthesis in the presence of insulin. ...
Drissi H - - 1999
Although calcitonin gene-related peptide (CGRP) may act as a local factor in bone, its mechanisms of action on osteoblasts are not well understood. We previously showed the presence of CGRP transcripts and peptide in human OHS-4 osteoblastic cells. The authors investigated the expression of CGRP receptor (CGRP-R) and its intracellular ...
Kozlowska M - - 1999
Purine riboside (purine-1-D-ribofuranoside, nebularine), an adenosine analog, exerts cytotoxic effect both in vivo and in vitro. However, exact biochemical mechanism for its toxicity and sensitivity of lymphoid cells remains unknown. The present experiments have examined the sequential metabolic changes leading to cell death, induced in cultured rat thymocytes during incubation ...
Klussmann E - - 1999
The antidiuretic hormone arginine-vasopressin (AVP) regulates water reabsorption in renal collecting duct principal cells by inducing a cAMP-dependent translocation of water channels (aquaporin-2, AQP-2) from intracellular vesicles into the apical cell membranes. In subcellular fractions from primary cultured rat inner medullary collecting duct (IMCD) cells, enriched for intracellular AQP-2-bearing vesicles, ...
Steinberger O - - 1999
The effect of the novel, naturally occurring nucleotide cyclic diguanylic acid (c-di-GMP) on the lymphoblastoid CD4+ Jurkat cell line was studied. When exposed to 50 microM c-di-GMP, Jurkat cells exhibited a markedly elevated expression of the CD4 receptor of up to 6.3-fold over controls. C-di-GMP also causes blockage of the ...
Mauriège P - - 1999
The aim of the present study was to examine whether site differences in s.c. adipose tissue (AT) lipolysis may be considered a contributing factor to the altered metabolic risk profile of visceral compared to peripheral obese men once the concomitant variation in adipose cell size is taken into account. For ...
Bak A - - 1999
PURPOSE: To evaluate the chemical and enzymatic stability, as well as the cellular permeation characteristics, of the acyloxyalkoxy-based cyclic prodrugs 1 and 2 of the opioid peptides [Leu5]-enkephalin (H-Tyr-Gly-Gly-Phe-Leu-OH) and DADLE (H-Tyr-D-Ala-Gly-Phe-D-Leu-OH), respectively. METHODS: The rates of conversion of 1 and 2 to [Leu5]-enkephalin and DADLE, respectively, were measured by ...
McDaid H M - - 1999
Taxol is a unique anticancer agent that is used in treatment of advanced ovarian cancer. Taxol exposure results in the polymerization and stabilization of the microtubule skeleton of eukaryotic cells, hence blocking replication and intracellular motility. 8-Chloro-adenosine 3',5'-monophosphate (8-Cl-cAMP) is a cAMP analogue, currently in Phase II clinical trials, that ...
Steiner MS - - 1999
Like many other carcinomas, prostate cancer develops resistance to inhibition by transforming growth factor (TGF)-&be;1 during oncogenesis. One proposed mechanism of TGF-&be;1 action posits action of the retinoblastoma protein (pRb) to suppress c-myc transcription to inhibit cellular proliferation. A metastatic human prostate cancer cell line, DU145, has both nonfunctional pRb ...
Sadanari H - - 1999
The effect of dibutyryl cyclic AMP (dbcAMP) on interaction of human cytomegalovirus (HCMV) with human central nervous system cell lines was examined. Activation of the major immediate-early (IE) promoter (MIEP) of HCMV by dbcAMP was observed in human neuroblastoma IMR-32 cells, but not in glioma 118MGC and astrocytoma U373-MG cells. ...
Mertens P R - - 1999
Calcitonin secretion by C-cells is mediated through intracellular 3'5'-cyclic adenosine monophosphate (cAMP) and calcium signaling. Calcitonin release stimulation tests may take advantage of both signaling cascades in screening for medullary thyroid carcinomas (MTC). To elucidate the regulation of the adenylyl cyclase system we have determined cAMP levels of a calcitonin-expressing ...
Borgen E - - 1999
BACKGROUND: Detection of isolated tumor cells (TC) in BM from carcinoma patients can predict future relapse. Various molecular and immunocytochemical (ICC) methods have been used to detect these cells, which are present at extremely low frequencies of 10(-5) - 10(-6). The specificity and sensitivity of these techniques may vary widely. ...
Haque M S - - 1998
PURPOSE: To characterize effects of endothelins on activities of phospholipase C (PLC) and nucleotide cyclases in human trabecular meshwork (TM) cells. METHODS: Cultured simian virus 40-transformed human TM (HTM-3) or non-transformed (HTM-16) cells were used. Changes in the PLC activity were determined by assaying the production of [3H] inositol phosphates. ...
Knight M M - - 1998
Mechanically induced cell deformation is one of a number of possible mechanotransduction pathways by which chondrocytes sense and respond to changes in their mechanical environment. The present study describes a system for measuring the deformation of isolated chondrocytes in agarose during both static and cyclic compression. A test rig mounted ...
Zimmermann-Belsing T - - 1998
Fischer rat thyroid cells (FRTL-5) are widely used for the study of thyroid cell function. With age or transformation the characteristics of FRTL-5 cells change, leading to poor differentiation and accelerated growth. Thyroglobulin production from FRTL-5 cells indicates differentiation to a higher extent than does the cyclic adenosine-3',5'-monophosphate (cAMP) response ...
Shafer S H - - 1998
This study investigated the effects of the adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase inhibitors caffeine, theophylline, and 3-isobutyl-1-methyl-xanthine (IBMX) on the proliferation and viability of the small cell lung carcinoma (SCLC) cell lines NCI-H345, NCI-H128, and SCC-9. These effects were correlated with the ability of the drugs to induce intracellular Ca2+ ...
Inoue M - - 1998
The expression of thyrotropin receptor (TSH-R) on various cells derived from bone, including osteoblast-like rat osteosarcoma cells (UMR106 cells), was investigated. TSH receptor mRNA was detected in UMR106 cells by Northern blot analysis. 125I-labeled TSH binding analysis revealed specific high- and low-affinity binding sites (association constants of 5.6 x 10(9) ...
Navarro J M - - 1998
Differences on 5'-nucleotidase activity in intact Rugli and BCS-TC2 cells (rat glioblastoma and human colon adenocarcinoma cell lines, respectively) are not due to differences in the characteristics of the ectoenzyme. A membrane-bound 5'-nucleotidase from BCS-TC2 cells has been purified to homogeneity with a high specific activity (130 U/mg), yielding a ...
Rillema J A - - 1998
In earlier studies the uptake of iodide into mammary cells was found to occur by a mechanism similar to that in thyroid cells (i.e., the uptake occurs via a sodium-iodide symporter that is inhibited by perchlorate and thiocyanate). Although cyclic AMP stimulates the iodide transport mechanism in thyroid cells, the ...
Kim D H - - 1998
Theophylline, a drug known to inhibit several classes of adenosine 3'5' cyclic monophosphate (cAMP) phosphodiesterases (PDEs), induces apoptosis in chronic lymphocytic leukemia (CLL) cells. Because the PDE target for theophylline in CLL remains unknown, we examined the ability of isoform-specific PDE inhibitors to increase cAMP levels and induce apoptosis in ...
Wiendl H S - - 1998
Extracellular ATP, when added as a single dose at concentrations higher than 0.1 mM to the culture medium, was growth inhibitory or even cytotoxic for human epidermoid carcinoma cells (A431). Adenosine at the same concentrations was much less potent. The molecular mechanism underlying the inhibitory effect of extracellular ATP has ...
Seybold J - - 1998
In this study, a potential mechanism of beta2-adrenoreceptor desensitization has been explored that is based upon the enhanced degradation of cAMP by phosphodiesterase (PDE). Pretreatment of Jurkat T-cells with 8-bromo cAMP (8-Br-cAMP) or prostaglandin E2 increased PDE3 and PDE4 activity in an actinomycin D- and cycloheximide-sensitive manner. This effect was ...
Veithen A - - 1998
Stable transformation of Rat-1 fibroblasts by the v-Src oncoprotein results into the constitutive formation of macropinosomes. In the present report, we found that macropinosomes do not fuse with transferrin-containing endosomes and investigated the effects of cyclic AMP as a regulator of macropinocytosis in this cell system. The permeant analogs dibutyryl ...
O'Reilly C M - - 1998
The regulation of chloride efflux from cystic fibrosis pancreatic adenocarcinoma cells (CFPAC-1) and wild-type CFTR-transfected CFPAC-1 cells (TPAC) was compared. Forskolin (10 microM) stimulated chloride efflux from the corrected TPAC cells but not from CFPAC-1 cells. Chloride efflux from both cell types was activated by thapsigargin (0.5 microM). The nucleotides ...
Quissell D O - - 1998
The purpose of this investigation was to develop well-differentiated rat parotid and submandibular acinar cell lines. Acinar cells dissociated from rat parotid and submandibular glands were grown on Mitomycin C-treated 3T3 fibroblasts or Matrigel in primary culture and transfected by CaPO4 precipitation using a plasmid containing a replication-defective simian virus ...
Toyoda T - - 1998
It generally is recognized that tensile load plays a major role in maintaining the homeostasis of the anterior cruciate ligament fibers, but its detailed mechanism remains a matter of controversy. The effect of cyclic tensile load on the metabolism of the anterior cruciate ligament were investigated experimentally using cultured cells ...
Tam V K - - 1998
The interaction of cells with the surrounding extracellular matrix (ECM) or basement membrane (BM) brings about profound changes in cellular biological responses, such as cell differentiation, proliferation, and gene expression. We studied the effect of ECM on PTH receptor binding and on biological responses mediated by PTH, in two cell ...
Spessert R - - 1998
In the rat pineal, formation of the second messenger cyclic GMP (cGMP) is under adrenergic control. Two important sequential steps mediate adrenergic signal transduction by cGMP, receptor-stimulated nitric oxide (NO) formation by the enzyme NO synthase I (NOS I), and NO-induced cGMP formation by the cytosolic enzyme guanylyl cyclase. With ...
Wilson P K - - 1998
BACKGROUND AND AIMS: the purine nucleoside analogues cladribine (CdA), fludarabine (F-Ara-AMP) and pentostatin (dCf), are effective therapy for a range of T- and B-cell lymphoid malignancies. The effects upon nucleotide metabolism in human CCRF-CEM T-cell leukaemia and Raji B-cell lymphoma cell lines of these drugs have been compared to assess ...
Juranić Z - - 1998
The effects of adenosine, aminophylline, dipyridamole and salbutamol on the amine oxidase-mediated spermine cytotoxicity to KS62 human myelogenous leukemia cells without Ph-chromosome, spontaneously enriched with mildly adherent cells, were studied. In the absence of spermine, adenosine expressed very mild inhibitory action on K562 cell survival, while in combination with the ...
Watt W C - - 1998
The cystic fibrosis (CF) transmembrane regulator (CFTR) is a cyclic AMP-dependent Cl- channel that is defective in CF cells. It has been hypothesized that CFTR exhibits an ATP release function that controls the airway surface ATP concentrations. In airway epithelial cells, CFTR-independent Ca2+-activated Cl- conductance is regulated by the P2Y2 ...
Brodsky A - - 1998
The present study examines the effects of forskolin on U937 cell differentiation. We recently reported that dibutyryl cAMP (dbcAMP), but not cAMP-elevating agents such as histamine, promotes U937 cell differentiation. cAMP production elicited by stimulation of histamine H2 receptors showed a rapid, homologous desensitization, which might explain the dissimilar responses ...
Doyle P S - - 1998
All parasitic protozoa examined to date are incapable of de novo synthesis of purine nucleotides and rely on salvage mechanisms for survival. We have identified hypoxanthine, guanine, xanthine phosphoribosyl-transferase activities in crude cell-free extracts of Cryptosporidium sporulated oocysts utilizing radiolabeled substrates. Guanine, hypoxanthine, and xanthine were converted to their corresponding ...
Girouard H - - 1998
The aim of this study was to investigate and clarify the role of prostaglandins (PG) on fat cell lipolysis in female rats. Incubations with adenosine deaminase (ADA) were used for the deamination of endogenous adenosine and increased basal (155%) and isoproterenol (10(-9) M) (348%) stimulation of glycerol release from adipocytes. ...
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