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At least 793 records · Page 44Linked to original sources
PubMed2005

Opsonized virulent Brucella abortus replicates within nonacidic, endoplasmic reticulum-negative, LAMP-1-positive phagosomes in human monocytes.

Cells in the Brucella spp. are intracellular pathogens that survive and replicate within host monocytes. Brucella maintains persistent infections in animals despite the production of high levels of anti-Brucella-specific antibodies. To determine the effect of antibody opsonization on the ability of Brucella to establish itself within monocytes, the intracellular trafficking of virulent Brucella abortus 2308 and attenuated hfq and bacA mutants was followed in the human monocytic cell line THP-1. Early trafficking events of B. abortus 2308-containing phagosomes (BCP) were indistinguishable from those seen for control particles (heat-killed B. abortus 2308, live Escherichia coli HB101, or latex beads). All phagosomes transiently communicated the early-endosomal compartment and rapidly matured into LAMP-1(+), cathepsin D(+), and acidic phagosomes. By 2 h postinfection, however, the number of cathepsin D(+) BCP was significantly lower for live B. abortus 2308-infected cells than for either Brucella mutant strains or control particles. B. abortus 2308 persisted within these cathepsin D(-), LAMP-1(+), and acidic vesicles; however, at the onset of intracellular replication, the numbers of acidic B. abortus 2308 BCP decreased while remaining cathepsin D(-) and LAMP-1(+). In contrast to B. abortus 2308, the isogenic hfq and bacA mutants remained in acidic, LAMP-1(+) phagosomes and failed to initiate intracellular replication. Notably, markers specific for the host endoplasmic reticulum were absent from the BCPs throughout the course of the infection. Thus, opsonized B. abortus in human monocytes survives within phagosomes that remain in the endosomal pathway and replication of virulent B. abortus 2308 within these vesicles corresponds with an increase in intraphagosomal pH.

Antibodies, Bacterial↗
PubMed2006

Plasmacytoid dendritic cell activation by foot-and-mouth disease virus requires immune complexes.

Natural IFN-producing cells (NIPC), also called plasmacytoid dendritic cells, represent an essential component of the innate immune defense against infection. Despite this, not much is known about the pathways involved in their activation by non-enveloped viruses. The present study demonstrates that the non-enveloped foot-and-mouth disease virus (FMDV) cannot stimulate IFN-alpha responses in NIPC, unless complexed with FMDV-specific immunoglobulins. Stimulation of NIPC with such immune complexes employs FcgammaRII ligation, leading to strong secretion of IFN-alpha. In contrast to the stimulation of NIPC by many enveloped viruses, FMDV induction of IFN-alpha production requires live virus. It is necessary for the virus to initiate its replicative cycle. Moreover, it is an abortive replication, as witnessed by the decrease of dsRNA levels and viral titers with time post infection. Sensitivity of the NIPC stimulation to wortmannin and chloroquin, but not leupeptin, indicates an essential role for the pre-lysosomal stage endosomal compartment. In conclusion, the present study demonstrates that immune complexes provide the means for a non-interferogenic virus to induce IFN-alpha responses by NIPC. This indicates an important link between NIPC and antibodies in immune responses against non-enveloped viruses such as FMDV.

Animals↗
PubMed1987

Role of human serum and cellular factors on the growth of peripheral blood CFU-gm.

The effects of fetal calf serum (FCS), autologous serum (AS) and pooled human serum (PS) on granulocyte-macrophage progenitors (CFU-gm) from normal human peripheral blood mononuclear non-adherent cells (MNAC) were studied to determine optimal growth conditions. PS provided fewer variations and better growth conditions than AS and FCS. Moreover, serum inhibitors affecting both autologous and heterologous CFU-gm were detected in a small group (10%) of donors. Since CFU-gm from different donors display a relatively uniform cell-cycle status and membrane phenotype, under optimal growth conditions the number of CFU-gm probably reflects the size of the circulating myeloid progenitor cell compartment.

Adult↗
PubMed1984

Coexpression of a PDGF-like growth factor and PDGF receptors in a human osteosarcoma cell line: implications for autocrine receptor activation.

The expression of both a PDGF-like growth factor and functional PDGF receptors within a clonal human osteosarcoma cell line (U-2 OS Cl 6) is demonstrated. These molecules are able to interact and induce tyrosine-specific phosphorylation and early actin reorganization in the osteosarcoma cells, effects similar to those that PDGF induces in normal responsive cells. Furthermore, immunoprecipitation with an antiserum against phosphotyrosine revealed that a 115 kd protein was constitutively phosphorylated in U-2 OS Cl 6 cells. A phosphorylated protein of similar apparent molecular weight has been found in human fibroblasts, but only after stimulation with PDGF. These data indicate that the PDGF-receptor-dependent pathway is constitutively activated in this cell line. Extracellularly added PDGF antibodies did not, however, affect the transformed properties or growth rate of U-2 OS Cl 6 cells in vitro. This indicates that autocrine PDGF receptor activation may be insignificant for maintaining the transformed state of this tumor cell line, or that autocrine receptor activation occurs in a compartment where it is inaccessible to extracellularly added antibodies.

Antibodies↗
PubMedDate not supplied

Neurobehavioral toxicity of methanol reflected by operant running.

Eleven Long-Evans male rats were trained to respond for food delivery by running in wheels under a Fixed Ratio = FR 20 schedule of reinforcement. Each 360 degrees rotation counted as a single response. Three food pellets were delivered for each reinforcement. The wheels, which provided transverse rods to be gripped by the rats, were specifically designed to reflect motor deficits produced by neurotoxicants. Each animal received two replicates of three different doses of methanol (50% in water): 1.0, 2.0, and 3.0 g/kg by gavage. The sequence for each animal was determined by a counterbalanced design. Gavage was followed by admitting the animal to the running wheel compartment 10 min later. Running wheel sessions lasted for 1 hour daily and were conducted 6 days/week. Statistical analyses showed insignificant differences between water and no-treatment control days, indicating no effect of the gavage procedure. However, a dose-effect relationship between methanol dose and responses per session proved statistically significant and linear (p < 0.0001) down to a dose equivalent to 10% of the LD50. In addition, detailed analyses of intervals between successive rotations (IRTs) indicated a displacement of the distribution toward longer intervals (decreased velocities) with increasing dose. The absence of a corresponding rise in the incidence of long pauses suggested that impaired coordination, reduced endurance, or their combination, rather than nonspecific variables, accounted for these results.

Animals↗
PubMed2005

Statistics of assay validation in high throughput cell imaging of nuclear factor kappaB nuclear translocation.

This report describes statistical validation methods implemented on assay data for inhibition of subcellular redistribution of nuclear factor kappaB (NF kappaB) in HeLa cells. We quantified cellular inhibition of cytoplasmic-nuclear translocation of NF kappaB in response to a range of concentrations of interleukin-1 (IL-1) receptor antagonist in the presence of IL-1alpha using eight replicate rows in each four 96-well plates scanned five times on each of 2 days. Translocation was measured as the fractional localized intensity of the nucleus (FLIN), an implementation of our more general fractional localized intensity of the compartments (FLIC), which analyzes whole compartments in the context of the entire cell. The NF kappaB antagonist assay (inhibition of IL-1- induced NF kappaB translocation) data were collected on a Q3DM (San Diego, CA) EIDAQtrade mark 100 high throughput microscopy system. [In 2003, Q3DM was purchased by Beckman Coulter Inc. (Fullerton, CA), which released the IC 100 successor to the EIDAQ 100.] The generalized FLIC method is described along with two-point (minimum-maximum) and multiple point titration statistical methods. As a ratio of compartment intensities that tend to change proportionally, FLIN was resistant to photobleaching errors. Two-point minimum-maximum statistical analyses yielded the following: a Z' of 0.174 with the data as n = 320 independent well samples; Z' by row data in a range of 0.393-0.933, with a mean of 0.766; by-plate Z' data of 0.310, 0.443, 0.545, and 0.794; and by-plate means of columns Z' data of 0.879, 0.927, 0.945, and 0.963. The mean 50% inhibitory concentration (IC50) for IL-1 receptor antagonist over all experiments was 213 ng/ml. The combined IC50 coefficients of variation (CVs) were 0.74%, 0.85%, 2.09%, and 2.52% for the four plates. Repeatability IC50 CVs were as follows: day to day 3.0%, row to row 8.0%, plate to plate 2.8%, and day to day 0.6%. The number of cells required for statistically resolvable differences in dose concentrations, plotted in a family of FLIN sigma/deltamicro (SD/range) curves and tabulated, demonstrated cell-by-cell assay precision with our combined sigma/deltamicro = 0.32 that required approximately 10-fold fewer cells than in a previously reported NF kappaB assay with sigma/deltamicro = 1.52. To better understand the relationship between cell-by-cell measurements and IC50 precision, 500 Monte Carlo simulations with varying cell-measurement SDs were used to explore three-, five-, seven-, and 11-point model titrations. The reductions in deltaIC50 90% confidence intervals from 11- to three-point titrations were 10-fold with the previously reported sigma/deltamicro = 1.52 and twofold with our sigma/deltamicro = 0.32. With these normalized parameters, this report provides a common statistical foundation, independent of the assay details, for evaluating the performance of imaging data on any instrument.

Active Transport, Cell Nucleus↗
PubMed1995

Infection of circulating and liver infiltrating T cells by hepatitis C virus of different subtypes.

Hepatitis C virus (HCV) infection display a very high rate of progression to chronicity and, like many other viruses causing persistent infections, it displays a tropism for the cells of the immune system. Peripheral blood mononuclear cells (PBMCs) from 21 HCV chronic carriers and long-term T cell clones derived from circulating or liver infiltrating T lymphocytes were tested by cDNA "nested" PCR for positive and negative strand HCV-RNA. The presence of HCV genomes in PBMCs is a frequent, although not constant, finding and can be accompanied by active viral replication, as suggested by the coexistence of negative strand HCV-RNA. Infected T cells are more represented in livers than in periphery, as indicated by comparing HCV-RNA detection in T cell clones isolated from both the compartments. Sequencing of viral genomes present in PBMCs and liver infiltrating lymphocytes showed that all the three major HCV genotypes present in our population of chronic carriers can infect lymphoid cells. Although each clonal population of T cells is infected by a single strain of HCV, in the same patient lymphoid cells can harbor different viral populations, different from those circulating at that moment in the serum.

Adult↗
PubMed2005

The amazing complexity of transcription factories.

Multicellular eukaryotes orchestrate immensely complex patterns of gene expression in order to define numerous specialised cell types. Patterns of expression are regulated at the level of DNA modification, chromatin structure, genome architecture and nuclear organisation. Each aspect of these features of regulation is controlled by complex nuclear systems, and each of the systems must interact to define a coherent regulatory network. In proliferating cells, and particularly during development, patterns of gene expression must be preserved in cells that have active DNA repair mechanisms and efficiently duplicate both DNA and the associated chromatin status--the histone code. The systems that regulate DNA synthesis and genome stability are integrated with those that regulate the efficacy of RNA synthesis, such that patterns of gene expression are maintained. This review analyses how different experimental approaches are revealing the amazing complexity of the transcriptionally active compartment of mammalian cells. The functional implications of this complexity will be discussed.

Animals↗
PubMed1998

Collagenous skeleton of the human mitral papillary muscle.

The papillary muscles (PM) of the heart have been the subject of numerous structural and functional studies. However, despite the importance of the collagenous compartment of the heart in the mechanical and electrical properties of the myocardium, little information is available on the structural organization of collagen within the PM. We study here the structural organization of collagen within the mitral papillary muscles (PM) of the human heart. Fragments of human mitral PM from normal and hypertensive subjects were macerated in NaOH to eliminate the cellular components. Macerated and nonmacerated samples were then studied with the scanning electron microscope (SEM). SEM shows that cardiac myocytes and endomysial capillaries are ensheathed in a layer of collagenous tissue. The myocyte sheath wall is formed by thin collagen fibers oriented at right angles to the main cell axis. These sheaths are open structures, collagen fibers continuing into adjacent sheaths at the points of lateral communications. Thick perimysial septa do not divide the PM tissue into separate compartments. Hypertensive hearts show perivascular and interstitial fibrosis. In addition, the lumen of the coronary vessels is reduced or obliterated, and large areas of the myocardium are substituted by densely packed collagen. Endomysial sheaths constitute a continuous collagenous layer that replicates the myocyte network. The endomysium should play a complex role in myocardial mechanics, assuring the equal distribution of force during the cardiac cycle. The absence of insulating boundaries should facilitate lateral propagation of excitation. Fibrosis in hypertensive hearts appears to be both reactive and reparative. The increase in the amount of collagen should greatly impair contractile capabilities and electrical conductance, severely compromise heart function, and contribute to development of heart failure.

Aged↗
PubMed1997

Differential oligonucleotide activity in cell culture versus mouse models.

The usual course of drug discovery begins with the demonstration of compound activity in cells and, usually, a lower level of activity in animals. Successive rounds of drug design may result in a compound with sufficient activity in animals to justify clinical trials. The basic endpoints of therapeutic oligonucleotide experiments include target antigen reduction, target messenger reduction and inhibition of transformed cell proliferation or viral replication. However, one should expect oligonucleotides to exhibit pleiotropic behaviour, as do all other drugs. In an animal oligonucleotides will necessarily bind to and dissociate from all macromolecules encountered in the blood, in tissues, on cell surfaces and within cellular compartments. Contrary to expectations, oligonucleotides designed to be complementary to certain transcripts have sometimes been found moderately effective in cell-free extracts, more effective in cell culture and most effective in animal models. If greater potency against standard endpoints is reported in mouse models than was observed in cell culture, critical examination must consider alternate modes of action in animals that may not apply in cell culture. This counterintuitive paradox will be examined, based on studies of Ha-ras expression in bladder cancer, Ki-ras expression in pancreatic cancer, erbB2 expression in ovarian cancer and c-myc expression in B cell lymphoma.

Animals↗
PubMed2006

Ehrlichia subversion of host innate responses.

Anaplasma (formerly Ehrlichia) phagocytophilum and Ehrlichia chaffeensis, upon infection of humans, replicate in host leukocyte granulocytes and monocytes/macrophages, respectively. These unusual Gram-negative bacteria lack genes for biosynthesis of the lipopolysaccharide and peptidoglycan that activate host leukocytes. Caveolae-mediated endocytosis directs A. phagocytophilum and E. chaffeensis to an intracellular compartment secluded from oxygen-dependent and -independent killing. Furthermore, these bacteria orchestrate a remarkable series of events that culminate in suppression of NADPH oxidase, phagocyte activation and differentiation pathways, apoptosis, and interferon-gamma signaling in host leukocytes. They offer a fascinating example of how pathogens employ intricate strategies to usurp and subvert host cell function.

Anaplasma↗
PubMed2000

Treatment-induced decline of human immunodeficiency virus-1 p24 and HIV-1 RNA in lymphoid tissue of patients with early human immunodeficiency virus-1 infection.

We report detailed quantitative analysis of human immunodeficiency virus-1 (HIV-1) p24 and HIV-1 RNA in tonsil biopsies from 13 patients with early, asymptomatic HIV infection before and during combination antiretroviral therapy. Using fluorescent microscopy in conjunction with reverse transcriptase-polymerase chain reaction of frozen tissue sections, we show that plasma and tissue viral loads decreased by approximately 3 logs during the 1-year treatment period, with good correlation between the HIV-1 p24 and HIV-1 RNA response in tissue. The decrease of tissue viral load was delayed compared to plasma viral load, possibly explained by the observation that the amount of follicular dendritic cell-associated virus correlated best with the area under the curve of plasma HIV-1 RNA throughout the last 12 weeks. Before and during treatment, the relative proportions of HIV-1 on follicular dendritic cells and within mononuclear cells remained constant, suggesting similar decay characteristics in these two lymphoid tissue compartments. However, viral p24 or RNA remained almost always detectable in tissue despite full suppression of HIV-1 RNA in plasma, and increased even after short-term rebounds in plasma viral load. Thus, full and sustained suppression of viral replication was required to efficiently decrease viral load in lymphoid tissue, but complete abolition of residual viral replication was not achieved.

Anti-HIV Agents↗
PubMed2004

Near-simultaneous and real-time detection of multiple analytes in affinity microcolumns.

A miniaturized immunoassay system based on beads in poly(dimethylsiloxane) microchannels for analyzing multiple analytes has been developed. The method involves real-time detection of soluble molecules binding to receptor-bearing microspheres, sequestered in affinity column format inside a microfluidic channel. Identification and quantitation of analytes occurs via direct fluorescence measurements or fluorescence resonance energy transfer. A preliminary account of this work based on single-analyte format has been published in this journal (Buranda, T.; Huang, J.; Perez-Luna, V. H.; Schreyer, B.; Sklar, L. A.; Lopez, G. P. Anal. Chem. 2002, 74, 1149-1156). We have extended the work to a multianalyte model system composed of discrete segments of beads that bear distinct receptors. Near-simultaneous and real-time detection of diverse analytes is demonstrated. The importance of this work is established in the exploration of important factors related to the design, assessment, and utility of affinity microcolumn sensors. First, beads derivatized with surface chemistry suitable for the attachment of fluorescently labeled biomolecules of interest are prepared and characterized in terms of functionality and receptor site densities by flow cytometry. Second, calibrated beads are incorporated in microfluidic channels. The analytical device that emerges replicates the basic elements of affinity chromatography with the advantages of microscale and real-time direct measurement of bound analyte on beads rather than the indirect determination from eluted sample typical of affinity chromatography. In addition, the two-compartment analysis of the assay data as demonstrated in single-analyte columns provides a template upon which the dynamics of multiple-analyte assays can be characterized using existing theoretical models and be tested experimentally. The assay can potentially detect subfemtomole quantities of protein with high signal-to-noise ratio and a large dynamic range spanning nearly 4 orders of magnitude in analyte concentration in microliter to submicroliter volumes of analyte fluid. The approach has the potential to be generalized to a host of bioaffinity assay methods including analysis of protein complexes (e.g., biomolecular indicators of diseases). Proof-of-principle analytes include FLAG peptide and carcinoembryonic antigen detected at physiologically relevant concentration levels.

Carcinoembryonic Antigen↗
PubMed2003

Intracellular activities of Salmonella enterica in murine dendritic cells.

Dendritic cells (DC) efficiently phagocytose invading bacteria, but fail to kill intracellular pathogens such as Salmonella enterica serovar Typhimurium (S. Typhimurium). We analysed the intracellular fate of Salmonella in murine bone marrow-derived DC (BM-DC). The intracellular proliferation and subcellular localization were investigated for wild-type S. Typhimurium and mutants deficient in Salmonella pathogenicity island 2 (SPI2), a complex virulence factor that is essential for systemic infections in the murine model and intracellular survival and replication in macrophages. Using a segregative plasmid to monitor intracellular cell division, we observed that, in BM-DC, S. Typhimurium represents a static, non-dividing population. In BM-DC, S. Typhimurium resides in a membrane-bound compartment that has acquired late endosomal markers. However, these bacteria respond to intracellular stimuli, because induction of SPI2 genes was observed. S. Typhimurium within DC are also able to translocate a virulence protein into their host cells. SPI2 function was not required for intracellular survival in DC, but we observed that the maturation of the Salmonella-containing vesicle is different in DC infected with wild-type bacteria and a strain deficient in SPI2. Our observations indicate that S. Typhimurium in DC are able to modify normal processes of their host cells.

Animals↗
PubMed2004

Reproduction of Langerin/CD207 traffic and Birbeck granule formation in a human cell line model.

Birbeck granules (BG) are organelles specific to Langerhans cells (LCs), which form where the C-type lectin Langerin accumulates. Their function remains obscure due to morphologic and dynamic alterations induced by maturation of isolated LC. In this study, we attempted to reconstitute Langerin traffic and BG formation in the endosomal pathway of a human melanoma cell line. In the selected Langerin-transfected cell line, M10-22E, Langerin is distributed between the early recycling endosomal compartment and the plasma membrane, as in LC. Whereas mainly concentrated in membranes related to the Rab11(+) endosomal recycling compartment at the steady state, Langerin also recycles in M10-22E cells and drives BG biogenesis in the endosomal recycling compartment. Interruption of endocytosis or recycling induces redistribution of intracellular Langerin with an associated alteration in BG location and morphology. We have, therefore, generated a stable, Langerin-transfected cell line in which Langerin traffic and distribution and BG morphology replicate that seen in freshly isolated LC. This practical model can now be used to further delineate the nature and function of BG.

Antigens, CD↗
PubMed2006

Diabetes promotes cardiac stem cell aging and heart failure, which are prevented by deletion of the p66shc gene.

Diabetes leads to a decompensated myopathy, but the etiology of the cardiac disease is poorly understood. Oxidative stress is enhanced with diabetes and oxygen toxicity may alter cardiac progenitor cell (CPC) function resulting in defects in CPC growth and myocyte formation, which may favor premature myocardial aging and heart failure. We report that in a model of insulin-dependent diabetes mellitus, the generation of reactive oxygen species (ROS) leads to telomeric shortening, expression of the senescent associated proteins p53 and p16INK4a, and apoptosis of CPCs, impairing the growth reserve of the heart. However, ablation of the p66shc gene prevents these negative adaptations of the CPC compartment, interfering with the acquisition of the heart senescent phenotype and the development of heart failure with diabetes. ROS elicit 3 cellular reactions: low levels activate cell growth, intermediate quantities trigger cell apoptosis, and high amounts initiate cell necrosis. CPC replication predominates in diabetic p66shc-/-, whereas CPC apoptosis and myocyte apoptosis and necrosis prevail in diabetic wild type. Expansion of CPCs and developing myocytes preserves cardiac function in diabetic p66shc-/-, suggesting that intact CPCs can effectively counteract the impact of uncontrolled diabetes on the heart. The recognition that p66shc conditions the destiny of CPCs raises the possibility that diabetic cardiomyopathy is a stem cell disease in which abnormalities in CPCs define the life and death of the heart. Together, these data point to a genetic link between diabetes and ROS, on the one hand, and CPC survival and growth, on the other.

Adaptor Proteins, Signal Transducing↗
PubMed1992

In vitro HIV-1 entry and replication in Langerhans cells may clarify the HIV-1 genome detection by PCR in epidermis of seropositive patients.

Being dendritic antigen-presenting cells in skin and mucous membrane, Langerhans cells (LC) occur in areas at risk for inoculation by human immunodeficiency virus (HIV), and the question whether LC act as a target, reservoir, or vector for transmission of HIV has given rise to much controversy. To address this question, we first analyzed the epidermal compartment of skin from patients seropositive for HIV DNA. Second, we tested the susceptibility of each cell type normally found in this compartment to in vitro infection by HIV-1. A non-denatured DNA was obtained from epidermal sheets after a thermochemical treatment of biopsies (0.5 M ethylenediaminetetraacetic acid (EDTA), pH 7.5 at 60 degrees C for 90 seconds). Optimization of amplification of viral genome was performed with three primer pairs derived from gag, env, and pol sequences. Polymerase chain reaction (PCR) products were analyzed by Southern blot. Viral genome was found in five of 11 HIV-seropositive patients. To control the permissivity of epidermal cell population for HIV, cells isolated from the epidermal sheet of normal skin by trypsinization were co-cultured with HIV-1-carrying promonocytic cells (U937) and observed by electron microscopy. After 3-6 h of co-culture, numerous virions were either tightly bound or apparently engaged in the process of internalization through receptor-mediated endocytosis. At day 4 of co-culture, some infected LC appeared to release mature viral particles through bud formation. The in vitro HIV-1 entry and replication in LC may confirm the presence of the HIV-1 genome by PCR in epidermis of seropositive patients. The consequences of the permissivity of LC for HIV on the antigen-presenting function remain to be determined.

DNA, Viral↗
PubMed2004

Comparative study of the short-term effects of a novel selective estrogen receptor modulator, ospemifene, and raloxifene and tamoxifen on rat uterus.

To investigate the differential short-term effects of selective estrogen receptor (ER) modulators (SERMs) on uterus, we treated adult ovariectomized rats with a novel SERM, ospemifene (Osp), two previously established SERMs (tamoxifen and raloxifene (Ral)) and estradiol. The expression of two estrogen-regulated early response genes c-fos and vascular endothelial growth factor (VEGF), and DNA synthesis were analysed at 1-24 h after treatment of ovariectomized rats. Induction of c-fos mRNA by each of the SERMs showed a biphasic pattern with peaks at 3 and 20 h, respectively. The maximum level of VEGF mRNA was observed at 1 h after raloxifene and 6 h after tamoxifen or ospemifene treatment. Maximum levels of the c-fos and VEGF mRNA after raloxifene treatment were higher than those seen after treatments with E2 or a corresponding dose of tamoxifen or ospemifene. DNA synthesis was significantly increased by ospemifene, tamoxifen and raloxifene both in luminal and glandular epithelium. The stimulation was transient, peaking at 16 h. In comparison, the maximum level observed at 16 h after E2 treatment sustained at least until 24 h. DNA synthesis in stromal cells was increased by the SERMs but not by E2 at 24 h. When treated together with E2, the SERMs were able to antagonise E2-stimulated DNA synthesis at 16 h. Our results demonstrate that the initial response of uterus to ospemifene, raloxifene and tamoxifen includes activation of early response genes and even transient stimulation of DNA synthesis in spite of their different long-term effects. However, the early stimulatory events may be mediated by different mechanisms leading to diverging pathways in various tissue compartments and development of differential SERM-specific long-term responses of uterus.

Animals↗