Biomedical subjects

A van de Stolpe

Publications and source records attributed to A van de Stolpe.

11 recordsLinked to original sources

PubMed2001

[From gene to disease; risk factors for venous thrombosis: factor V Leiden and prothrombin 20210A].

Venous thromboembolic disease is an important clinical entity, in which both acquired and genetic risk factors play a causative role. Genetic factors which increase thrombotic risk consist of rare heterogeneous loss-of-function mutations in coagulation-inhibitory factors, such as antithrombin, protein S and C, and more common, but unique, gain-of-function mutations in coagulation factors V and II, so-called factor V-Leiden and prothrombin 20210A. The genetic defect underlying factor V-Leiden is a guanine (G) to adenine (A) mutation in the factor V gene, causing substitution of arginine at position 506 by glutamine, thereby providing resistance to proteolytic cleavage by activated protein C (APC). In the prothrombin 20210A allele a G to A mutation at nucleotide 20210 in the 3'-untranslated region of the prothrombin gene is associated with increased prothrombin levels. The APC-resistance assay is used to screen for the presence of factor V-Leiden. Both factor V-Leiden and prothrombin 20210A are diagnosed by DNA analysis.

Activated Protein C Resistance↗

PubMed1997

NF-kappa B/Rel family members regulating the ICAM-1 promoter in monocytic THP-1 cells.

A kappa B-site was identified in the promoter of the intercellular adhesion molecule-1 (ICAM-1) gene, which is involved in regulation of ICAM-1 expression by tumor necrosis factor alpha (TNF-alpha) and glucocorticoids. We now report on the transcription factors which bind and transactivate this enhancer sequence. In vitro, the ICAM-1 kappa B site appeared to bind RelA and c-Rel homodimers as well as heterodimers with NF-kappa B1, but weakly NF-kappa B1 homodimers. In addition, both RelA and c-Rel, but not NF-kappa B1, were shown to transactivate an ICAM-1 kappa B-reporter construct. In monocytic THP-1 cells TNF-alpha induced two nuclear complexes which in vitro bound to the ICAM-1 kappa B site. Using antibodies in an electrophoretic mobility supershift assay, one of these complexes was shown to contain NF-kappa B1 and RelA, and to bind with higher affinity to the consensus kappa B site in the HIV long terminal repeat. The second complex contained RelA, and exhibited higher affinity towards the ICAM-1 kappa B than to the HIV kappa B site. The glucocorticoid receptor was shown to repress activity of both the RelA homodimer and the NF-kappa B1/RelA heterodimer. We argue that in vivo RelA homodimers are likely to play a dominant role in TNF-alpha-induced ICAM-1 transcription in monocytic cells.

Animals↗

PubMed1996

Intercellular adhesion molecule-1.

The intercellular adhesion molecule (ICAM) 1 is an Ig-like cell adhesion molecule expressed by several cell types, including leukocytes and endothelial cells. It can be induced in a cell-specific manner by several cytokines, for example, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma, and inhibited by glucocorticoids. Its ligands are the membrane-bound integrin receptors LFA-1 and Mac-1 on leukocytes, CD43, the soluble molecule fibrinogen, the matrix factor hyaluronan, rhinoviruses, and Plasmodium falciparum malaria-infected erythrocytes. ICAM-1 expression is predominantly transcriptionally regulated. The ICAM-1 promoter contains several enhancer elements, among them a novel kappa B element which mediates effects of 12-O-tetradecanoylphorbol-13-acetate, interleukin-1, lipopolysaccharide, tumor necrosis factor-alpha, and glucocorticoids. Expression regulation is cell specific and depends on the availability of cytokine/hormone receptors, signal transduction pathways, transcription factors, and posttranscriptional modification. ICAM-1 plays a role in inflammatory processes and in the T-cell mediated host defense system. It functions as a costimulatory molecule on antigen-presenting cells to activate MHC class II restricted T-cells, and on other cell types in association with MHC class I to activate cytotoxic T-cells. ICAM-1 on endothelium plays an important role in migration of (activated) leukocytes to sites of inflammation. ICAM-1 is shed by the cell and detected in plasma as sICAM-1. Regulation and significance of sICAM-1 are as yet unclear, but sICAM-1 is increased in many pathological conditions. ICAM-1 may play a pathogenetic role in rhinovirus infections. Derangement of ICAM-1 expression probably contributes to the clinical manifestations of a variety of diseases, predominantly by interfering with normal immune function. Among these are malignancies (e.g., melanoma and lymphomas), many inflammatory disorders (e.g., asthma and autoimmune disorders), atherosclerosis, ischemia, certain neurological disorders, and allogeneic organ transplantation. Interference with ICAM-1 leukocyte interaction using mAbs, soluble ICAM-1, antisense ICAM-1 RNA, and in the case of melanoma mAb-coupled immunotoxin, may offer therapeutic possibilities in the future. Integration of knowledge concerning membrane-bound and soluble ICAM-1 into a single functional system is likely to contribute to elucidating the immunoregulatory function of ICAM-1 and its pathophysiological significance in various disease entities.

Animals↗

PubMed1996

Fibrinogen binding to ICAM-1 on EA.hy 926 endothelial cells is dependent on an intact cytoskeleton.

Fibrinogen is a ligand for Intercellular Adhesion Molecule-1 (ICAM-1), and enhances monocyte-endothelial cell interaction by coupling Mac-1 on monocytes to ICAM-1 on endothelial cells. We investigated the role of the cytoskeleton in fibrinogen binding to the human endothelial cell line EA.hy 926 using immunofluorescence techniques. In this cell line TNF alpha induced the simultaneous appearance of stress fibers and of ICAM-1, which was clustered predominantly on endothelial cell projections. Incubation of TNF alpha-stimulated endothelial cells with fibrinogen resulted in binding of fibrinogen to ICAM-1 on these cell projections. Disruption of the cytoskeleton by cytocholasin B abolished fibrinogen binding. Activation of protein kinase C with 12-O-tetradecanoyl phorbol-13-acetate resulted in simultaneous loss of both stress fibers and fibrinogen binding. These results suggest that a connection between ICAM-1 and the cytoskeleton results in clustering of ICAM-1 on cell projections, which is required for fibrinogen binding.

Cell Line↗

PubMed1996

Molecular mechanisms of steroid action: a novel type of cross-talk between glucocorticoids and NF-kappa B transcription factors.

Despite the widespread use of glucocorticoids in the treatment of diseases characterized by inflammation, the molecular mechanism(s) by which these hormones exert this beneficial effect in patients with asthma remains to be elucidated. Therefore, we have studied the transcriptional regulation of intercellular adhesion molecule-1 (ICAM-1) as adhesion molecules are likely to play a causal role in inflammation in promoting cell-cell and cell-matrix interactions. We observed that in a monocytic (U937) and a bronchial epithelial (H292) cell-line dexamethasone strongly suppressed basal and induced ICAM-1 expression. Subsequent analysis of the human ICAM-1 promoter has revealed that both 12-O-tetradecanoylphorbol 13-acetate (TPA) and tumour necrosis factor-alpha (TNF-alpha) upregulate ICAM-1 expression through the presence of a nuclear factor (NF-kappa B) target sequence (TGGAAATTCC). No glucocorticoid recognition sequences are present in this promoter region and dexamethasone is still able to repress transcription when the multimerized NF-kappa B sequence is transactivated by TNF-alpha upon transfection in 293 cells. We propose that direct interaction between the glucocorticoid receptor and nuclear factor-kappa B factors is at least a partial explanation for the effects of this hormone in inflammatory diseases.

Animals↗

PubMed1994

12-O-tetradecanoylphorbol-13-acetate- and tumor necrosis factor alpha-mediated induction of intercellular adhesion molecule-1 is inhibited by dexamethasone. Functional analysis of the human intercellular adhesion molecular-1 promoter.

Transcription regulation of the human intercellular adhesion molecule-1 gene by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), tumor necrosis factor alpha (TNF alpha), and the glucocorticoid dexamethasone was studied using transient transfections in 293 cells with intercellular adhesion molecule-1 promoter-luciferase constructs (together with a glucocorticoid receptor expression vector). TPA and TNF alpha induced promoter activity, which was repressed by dexamethasone. Four TPA-responsive DNA regions were identified, each containing a potential TPA-responsive enhancer sequence: 1) -677/-340 an AP3-like sequence; 2) -290/278 a TPA-response element (TRE); 3) -227/-175 an NF kappa B-like sequence; 4) -105/-38 an AP2-like sequence. TNF alpha enhanced transcription only through region 3. The TRE in region 2 appeared to be functionally coupled to a distal TATA box at -313 and differed from the consensus TRE with respect to binding characteristics for members of the AP1 family. The newly identified NF kappa B enhancer (TGGAAATTCC) is bound by a TNF alpha-induced nuclear protein and appears to be the key element in rapid transcription induction by TNF alpha (and TPA), while transactivation of this element is repressed by the ligand-bound glucocorticoid receptor. We propose a negative cross-talk between the NF kappa B transcription factor and the glucocorticoid receptor.

Base Sequence↗

PubMed1993

Parathyroid hormone-related peptide as an endogenous inducer of parietal endoderm differentiation.

Parathyroid hormone related peptide (PTHrP), first identified in tumors from patients with the syndrome of "Humoral Hypercalcemia of Malignancy," can replace parathyroid hormone (PTH) in activating the PTH-receptor in responsive cells. Although PTHrP expression is widespread in various adult and fetal tissues, its normal biological function is as yet unknown. We have examined the possible role of PTHrP and the PTH/PTHrP-receptor in early mouse embryo development. Using F9 embryonal carcinoma (EC) cells and ES-5 embryonic stem (ES) cells as in vitro models, we demonstrate that during the differentiation of these cells towards primitive and parietal endoderm-like phenotypes, PTH/PTHrP-receptor mRNA is induced. This phenomenon is correlated with the appearance of functional adenylate cyclase coupled PTH/PTHrP-receptors. These receptors are the mouse homologues of the recently cloned rat bone and opossum kidney PTH/PTHrP-receptors. Addition of exogenous PTH or PTHrP to RA-treated EC or ES cells is an efficient replacement for dBcAMP in inducing full parietal endoderm differentiation. Endogenous PTHrP is detectable at very low levels in undifferentiated EC and ES cells, and is upregulated in their primitive and parietal endoderm-like derivatives as assessed by immunofluorescence. Using confocal laser scanning microscopy on preimplantation mouse embryos, PTHrP is detected from the late morula stage onwards in developing trophectoderm cells, but not in inner cell mass cells. In blastocyst stages PTHrP is in addition found in the first endoderm derivatives of the inner cell mass. Together these results indicate that the PTH/PTHrP-receptor signalling system serves as a para- or autocrine mechanism for parietal endoderm differentiation in the early mouse embryo, thus constituting the earliest hormone receptor system involved in embryogenesis defined to date.

Adenylyl Cyclases↗

PubMed1993

Glucocorticoid-mediated repression of intercellular adhesion molecule-1 expression in human monocytic and bronchial epithelial cell lines.

Increased expression of the intercellular adhesion molecule-1 (ICAM-1) on cells present in the airways has been suggested to play a role in the pathogenesis of asthma by enhancing airway inflammation. We used the monocytic U937 cell line, both undifferentiated and differentiated to a macrophage-like phenotype, and the bronchial epithelial cell line NCI-H292 as cellular model systems for human monocytes/macrophages and bronchial epithelial cells, respectively, and studied the effects of 12-O-tetradecanoyl phorbol-13-acetate (TPA) and dexamethasone on ICAM-1 expression. Both cell lines expressed the ICAM-1 protein constitutively. In addition, TPA- or 1,25-dihydroxyvitamin D3-mediated differentiation of the U937 cell line into a macrophage-like phenotype was associated with increased expression of ICAM-1. In both cell lines, two ICAM-1 mRNA transcripts were found, and expression was stimulated to a similar degree within 1 to 2 h after addition of TPA. In both cell lines, the anti-inflammatory corticosteroid dexamethasone repressed both constitutive and TPA-stimulated ICAM-1 expression, within 3 h of its addition. In the presence of cycloheximide, a marked superinduction of ICAM-1 was observed, while the repressive effect of dexamethasone remained, supporting the hypothesis that dexamethasone acts directly at the transcriptional level.

Antibodies, Monoclonal↗

PubMed1990

Effects of atrial natriuretic peptide on distal tubule function in humans.

To characterize the actions of atrial natriuretic peptide (ANP) in the human distal nephron, we studied interactions between ANP (0.02 micrograms/kg.min i.v.) and acutely administered substances acting in the distal nephron, that is, amiloride and aldosterone, in six healthy humans during maximal water diuresis. ANP increased NaCl excretion, fractional lithium excretion (FELi) and decreased diluting segment reabsorption estimated from free water clearance. Amiloride increased natriuresis, had no effect on FELi, but decreased diluting segment reabsorption. Aldosterone had the opposite effect. When infused in addition to amiloride, ANP still increased NaCl excretion, the changes in sodium handling parameters being comparable to those seen after ANP alone. Amiloride did not increase the further natriuretic response to ANP. These findings suggest that ANP increases distal sodium delivery, and decreases sodium reabsorption in distal segments by a mechanism also sensitive to amiloride. ANP abolished much of the antinatriuretic effect of aldosterone, which may also be explained by assuming a partial overlap of the target segments of ANP and aldosterone in the distal nephron. Remarkably, in neither of these experiments was the natriuresis after ANP accompanied by a kaliuresis, for which the explanation remains obscure.

Adult↗

PubMed1988

Micropuncture study of the effect of ANP on the papillary collecting duct in the rat.

Micropuncture collections were obtained from the terminal collecting duct (CD) at base and tip of the renal papilla of the rat. Group 1 was studied before and during infusion with atrial natriuretic peptide (ANP), group 2 was administered the vehicle only, and group 3 received acetazolamide to increase sodium delivery to the base to a similar extent as after ANP. ANP caused a decrease in blood pressure, a slight increase in GFR, natriuresis, and diuresis. Sodium delivery to the collecting duct at the base of the papilla increased. Between base and tip, sodium reabsorption was inhibited. Tubule fluid sodium concentration (TFNa) was increased at the base and remained high at the tip; in contrast TFNa fell between base and tip in control and acetazolamide groups. After acetazolamide, sodium reabsorption in the terminal CD was not inhibited. These results demonstrate that in vivo ANP 1) increases the delivery of sodium to the terminal CD and 2) inhibits sodium reabsorption in the terminal CD. The findings for chloride were similar to those for sodium. ANP also increased delivery of H2O, K, Ca, and Mg to the CD at the papillary base but did not significantly affect their transport by the terminal CD.

Acetazolamide↗

PubMed1987

Total body potassium in Bartter's syndrome before and during treatment with enalapril.

Total Body Potassium (TBK) was measured by whole body counting of 40K in 3 patients with Bartter's syndrome before, after 3 months and after 1 year of treatment with enalapril. In 2 patients TBK was found to be decreased before treatment, whereas TBK was within the normal range in the 3rd. During treatment serum potassium concentration and TBK increased in each subject and symptoms of fatigue and tetany disappeared. Enalapril is shown to be an effective treatment in Bartter's syndrome as it improves serum potassium, TBK and complaints.

Adult↗