Chris van der Bent

Leiden University Medical Centre, Leyden, South Holland, Netherlands

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Publications (11)41.14 Total impact

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    ABSTRACT: Women with a history of mainly severe and early onset preeclampsia have an increased risk of future cardiovascular disease. During these complicated pregnancies increased levels of anti-angiogenic factors can be found. We hypothesize that women with a history of severe very early onset preeclampsia still have increased levels of these biomarkers years after this pregnancy, resulting in increased risk for cardiovascular disease. Twenty women with severe early onset preeclampsia before 24 weeks' gestation, who delivered between 1993-2003 in a tertiary referral centre and twenty matched controls with uncomplicated pregnancies and healthy term infants, were addressed for participation in the study. Venous plasma samples were analyzed for basic fibroblast growth factor (bFGF), placental growth factor (PLGF), soluble fms-like tyrosine kinase-1 (sFlt-1), vascular endothelial growth factor (VEGF), E- and P-selectin, soluble intercellular adhesion molecule-3 (sICAM-3) and thrombomodulin by ELISA. Sixteen case subjects and 18 control subjects consented participation. The median time interval index pregnancy to study was 9.4 and 9.7 years for cases and controls, respectively. Median levels for cases-controls (p-value) were not different; bFGF: 17.43-11.11 pg/mL (0.33), sFlt-1: 102.98-101.92 pg/ml (0.84), PLGF: 3.57-4.20 pg/mL (0.38), VEGF: 64.05-45.72 pg/mL (0.73), E-selectin: 5.11-4.68 ng/mL (0.20), P-selectin: 85.35-71.69 ng/mL (0.69), sICAM-3: 0.42-0.63 ng/mL (0.41) and Thrombomodulin: 0.92-0.93 ng/mL (0.59). There were no differences in angiogenic biomarkers between women with a history of severe early onset preeclampsia versus uncomplicated pregnancy almost 10 years later, suggesting that these angiogenic factors will not contribute to the early detection of women at risk for future cardiovascular disease.
    PLoS ONE 01/2012; 7(8):e43637. · 3.53 Impact Factor
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    ABSTRACT: To test the hypothesis that the increased risk of type 2 diabetes mellitus and coronary artery disease in South Asian subjects could be caused by the presence of endothelial dysfunction in early life. We studied markers of endothelial dysfunction in umbilical cord blood of South Asian neonates and compared these with that of Caucasian control subjects. From South Asian (n = 57) and Caucasian (n = 21) neonates, cord blood was collected and levels of glucose, insulin, lipids, and markers of endothelial dysfunction (E-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1) and inflammation (C-reactive protein) were measured. Plasma E-selectin levels were significantly higher in South Asian neonates (46.7 versus 33.5 ng/mL, P < .001), and levels of intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 did not differ. Furthermore, South Asian neonates had hyperinsulinemia (P = .043), dyslipidemia (with significantly higher triglyceride and lower high-density lipoprotein cholesterol levels), and higher C-reactive protein levels (75.7 versus 43.8 ng/mL, P = .009). South Asian newborns are characterized by elevated E-selectin levels in line with the hypothesis that endothelial dysfunction is present early in life. In addition, hyperinsulinemia, dyslipidemia, and inflammation are present. Because many pathogenic variables for coronary artery disease and type 2 diabetes are already present at birth in South Asian patients, the question arises whether rigorous childhood lifestyle intervention could be beneficial.
    The Journal of pediatrics 12/2011; 160(5):844-8.e1. · 4.02 Impact Factor
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    ABSTRACT: Objective. This study aims to evaluate the effect of a multidisciplinary treatment of obesity on plasma concentrations of several gut hormones in fasting condition and in response to a mixed meal in children. Methods. Complete data were available from 36 obese children (age 13.3 ± 2.0 yr). At baseline and after the 3-month multidisciplinary treatment, fasting and postprandial blood samples were taken for glucose, insulin, ghrelin, peptide YY (PYY), and glucagon-like peptide 1 (GLP-1). Results. BMI-SDS was significantly reduced by multidisciplinary treatment (from 4.2 ± 0.7 to 4.0 ± 0.9, P < .01). The intervention significantly increased the area under the curve (AUC) of ghrelin (from 92.3 ± 18.3 to 97.9 ± 18.2 pg/L, P < .01), but no significant changes were found for PYY or GLP-1 concentrations (in fasting or postprandial condition). The insulin resistance index (HOMA-IR) remained unchanged as well. Conclusion. Intensive multidisciplinary treatment induced moderate weight loss and increased ghrelin secretion, but serum PYY and GLP-1 concentrations and insulin sensitivity remained unchanged.
    ISRN endocrinology. 01/2011; 2011:353756.
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    ABSTRACT: Huntington's disease (HD) is a fatal hereditary neurodegenerative disorder caused by an increased CAG repeat size in the huntingtin gene. Apart from neurological impairment, the disease is also accompanied by progressive weight loss, abnormalities in glucose homeostasis and a higher prevalence of diabetes mellitus, which may partly be caused by disturbed growth hormone (GH) and ghrelin secretion. Therefore, we aimed to perform a detailed analysis of GH and ghrelin secretion in HD patients in relation to clinical signs and symptoms. In nine early-stage, medication-free HD patients and nine age-, gender- and body mass index-matched controls, we measured serum GH levels every 10 min for 24 h and assessed ghrelin response to food intake. Multi-parameter auto-deconvolution and approximate entropy analysis were applied to quantify basal, pulsatile, and total GH secretion rates as well as the regularity of GH secretion. We found no significant differences in GH and ghrelin secretion characteristics between HD patients and controls (total GH secretion: 137 +/- 36 vs. 181 +/- 43 mU/l/24 h, respectively; P = 0.439). However, in HD patients, both GH secretion and its irregularity as well as the degree of postprandial ghrelin suppression significantly increased with worsening motor and functional impairment (all P < 0.05). Moreover, postprandial ghrelin suppression also increased with decreasing body weight and higher CAG repeat number (both P < 0.05). These findings suggest changes in the regulation of GH and ghrelin secretion dynamics in early stage HD patients that could become more prominent in the later stages of the disease.
    European Journal of Neurology 10/2009; 17(2):280-8. · 4.16 Impact Factor
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    ABSTRACT: Sleep disturbances are very prevalent in Huntington's disease (HD) patients and can substantially impair their quality of life. Accumulating evidence suggests considerable dysfunction of the hypothalamic suprachiasmatic nucleus (SCN), the biological clock, in both HD patients and transgenic mouse models of the disease. As melatonin has a major role in the regulation of sleep and other cyclical bodily activities and its synthesis is directly regulated by the SCN, we postulated that disturbed SCN function is likely to give rise to abnormal melatonin secretion in HD. Therefore, we compared 24 h melatonin secretion profiles between early stage HD patients and age-, sex- and body mass index-matched controls. Although mean diurnal melatonin levels were not different between the two groups (p = 0.691), the timing of the evening rise in melatonin levels was significantly delayed by more than 01:30 h in HD patients (p = 0.048). Moreover, diurnal melatonin levels strongly correlated with both motor (r = -0.70, p = 0.036) and functional impairment (r = +0.78, p = 0.013). These findings suggest a delayed sleep phase syndrome-like circadian rhythm disorder in early stage HD patients and suggest that melatonin levels may progressively decline with advancing disease.
    Journal of Neurology 07/2009; 256(12):1961-5. · 3.58 Impact Factor
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    ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs) and cyclo-oxygenase (COX) inhibitors are anti-inflammatory agents that have also shown to be useful in anticancer therapy. In the present study, we show that the specific COX-2 inhibitor celecoxib enhances the inhibitory effect of doxorubicin (dox) on human MDA-MB231 breast tumour growth in vivo and in vitro. We also found that celecoxib increased the intracellular accumulation and retention of dox in vitro. Since the NSAID indomethacin and the specific COX-2 inhibitor NS398 did not affect the in vitro actions of dox, these effects are likely to be mediated via a COX-independent mechanism. It has been suggested that some COX-inhibitors can enhance the actions of cytostatics by overcoming multidrug resistance through the inhibition of ABC-transporter proteins. However, we found that the three main ATP-binding cassette (ABC)-transporter proteins, implicated in dox transport, were inactive in MDA-MB231 cells. Therefore, the finding that the P-glycoprotein (P-gp) blocker PSC833 also increased cellular accumulation of dox was unexpected. In order to unravel the molecular mechanisms involved in dox accumulation, we examined the involvement of NF-kappaB, as this transcription factor has been implicated in celecoxib action as well as in chemoresistance. We found that celecoxib and PSC833, but not indomethacin or NS398, almost completely inhibited basal- and dox induced NF-kappaB gene-reporter activity and p65 subunit nuclear translocation. Furthermore, the NF-kappaB inhibitor PDTC mimicked the actions of celecoxib and PSC833 on cell growth and on intracellular accumulation of dox, suggesting that NF-kappaB is functionally involved in the actions of these compounds. In conclusion, we show that structurally different compounds, among which are celecoxib and PSC833, increase the intracellular accumulation of dox and enhance dox induced cytotoxicity in MDA-MB231 breast cancer cells most likely via the modulation of NF-kappaB activity.
    European Journal of Cancer 02/2007; 43(2):433-42. · 5.06 Impact Factor
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    ABSTRACT: During bone formation and fracture healing there is a cross-talk between endothelial cells and osteoblasts. We previously showed that vascular endothelial growth factor A (VEGF-A) might be an important factor in this cross-talk, as osteoblast-like cells produce this angiogenic factor in a differentiation-dependent manner. Moreover, exogenously added VEGF-A enhances osteoblast differentiation. In the present study we investigated, given the coupling between angiogenesis and bone formation, whether bone morphogenetic proteins (BMPs) stimulate osteoblastogenesis and angiogenesis through the production of VEGF-A. For this we used the murine preosteoblast-like cell line KS483, which forms mineralized nodules in vitro, and an angiogenesis assay comprising 17-d-old fetal mouse bone explants that have the ability to form tube-like structures in vitro. Treatment of KS483 cells with BMP-2, -4, and -6 enhanced nodule formation, osteocalcin mRNA expression, and subsequent mineralization after 18 d of culture. This was accompanied by a dose-dependent increase in VEGF-A protein levels throughout the culture period. BMP-induced osteoblast differentiation, however, was independent of VEGF-A, as blocking VEGF-A activity by a VEGF-A antibody or a VEGF receptor 2 tyrosine kinase inhibitor did not affect BMP-induced mineralization. To investigate whether BMPs stimulate angiogenesis through VEGF-A, BMPs were assayed for their angiogenic activity. Treatment of bone explants with BMPs enhanced angiogenesis. This was inhibited by soluble BMP receptor 1A or noggin. In the presence of a VEGF-A antibody, both unstimulated and BMP-stimulated angiogenesis were arrested. Conditioned media of KS483 cells treated with BMPs also induced a strong angiogenic response, which was blocked by antimouse VEGF-A but not by noggin. These effects were specific for BMPs, as TGF beta inhibited osteoblast differentiation and angiogenesis while stimulating VEGF-A production. These findings indicate that BMPs stimulate angiogenesis through the production of VEGF-A by osteoblasts. In conclusion, VEGF-A produced by osteoblasts in response to BMPs is not involved in osteoblast differentiation, but couples angiogenesis to bone formation.
    Endocrinology 05/2002; 143(4):1545-53. · 4.72 Impact Factor
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    ABSTRACT: Interactions between specific cell-surface molecules, which include the urokinase receptor (uPAR) and integrins, are crucial to processes of tumor invasion and metastasis. Here we demonstrate that uPAR and beta1-integrins may cluster at distinct sites at the cell surface of metastatic MDA-MB-231 breast cancer cells and form functional complexes. Attachment assays performed in the presence of a synthetic peptide (p25), which interferes with the formation of uPAR-integrin complexes, reveal that uPAR is able to regulate the adhesive function of integrins in breast cancer cells. On dissociation of the uPAR-integrin complexes by p25, tumor cell attachment to the extracellular matrix was either decreased (vitronectin) or increased (fibronectin). Moreover, the tumor cells display remarkable morphological changes when cultured on fibronectin in the continuous presence of p25, leading to increased cell spreading and attachment. In marked contrast to control conditions, increased cellular adhesion to fibronectin after p25 treatment was entirely beta1-integrin-mediated. The role of uPAR-integrin complexes in tumor progression was studied in an in vivo bone xenograft model. Stably transfected MDA-MB-231 cells that overexpress p25 showed a significant reduction in tumor progression in bone (P < or = 0.0001 versus mock-control). In line with these observations, continuous administration of p25 (25 microg/mouse/day, osmotic minipumps) for 28 days resulted in significantly reduced tumor progression of MDA-MB-231 cells in bone (P < or = 0.005) when compared to scrambled control peptide. In conclusion, our data demonstrate that uPAR can act as an adhesion receptor in breast cancer and is capable of regulating integrin function. Our findings strongly suggest that adhesive and proteolytic events are tightly associated in metastatic breast cancer cells and that functional integrin-uPAR complexes are involved in tumor progression in vivo.
    American Journal Of Pathology 10/2001; 159(3):971-82. · 4.60 Impact Factor
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    ABSTRACT: Endochondral bone formation is regulated by systemically and locally acting growth factors. A role for vascular endothelial growth factor (VEGF) in this process has recently been proposed, because inactivation of VEGF inhibits endochondral bone formation via inhibition of angiogenesis. Despite the known effect of VEGF as specific endothelial growth factor, its effects on osteoblast differentiation have not been studied. We, therefore, examined the expression of VEGF-A, -B, -C, and -D and their receptors in a model of osteoblast differentiation using the mouse preosteoblast-like cell line KS483. Early in differentiation, KS483 cells express low levels VEGF-A, -B, and -D messenger RNA, whereas during mineralization, KS483 cells express high levels. In addition, expression of the VEGF receptors, VEGFR1, VEGFR2, and VEGF165R/neuropilin, coincided with expression of their ligands, being maximally expressed during mineralization. VEGF-A production during osteoblast differentiation was stimulated by insulin-like growth factor I that enhances osteoblast differentiation and was inhibited by PTH-related peptide that inhibits osteoblast differentiation. Furthermore, continuous treatment of KS483 cells with recombinant human VEGF-A stimulated nodule formation. Although treatment of KS483 cells with soluble FLT1, an agent that blocks binding of VEGF-A and -B to VEGFR1, did not inhibit nodule formation, this observation does not exclude involvement of VEGFR2 in the regulation of osteoblast differentiation. As it is known that VEGF-A, -C, and -D can act through activation of VEGFR2, other isoforms might compensate for VEGF-A loss. The expression pattern of VEGFs and their receptors shown here suggests that VEGFs play an important role in the regulation of bone remodeling by attracting endothelial cells and osteoclasts and by stimulating osteoblast differentiation.
    Endocrinology 06/2000; 141(5):1667-74. · 4.72 Impact Factor
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    ABSTRACT: Endochondral bone formation is regulated by systemically and locally acting growth factors. A role for vascular endothelial growth factor (VEGF) in this process has recently been proposed, because inactivation of VEGF inhibits endochondral bone formation via inhibition of angiogenesis. Despite the known effect of VEGF as specific endothelial growth factor, its effects on osteoblast differentiation have not been studied. We, therefore, examined the expression of VEGF-A, -B, -C, and -D and their receptors in a model of osteoblast differentiation using the mouse preosteoblast-like cell line KS483. Early in differentiation, KS483 cells express low levels VEGF-A, -B, and -D messenger RNA, whereas during mineralization, KS483 cells express high levels. In addition, expression of the VEGF receptors, VEGFR1, VEGFR2, and VEGF165R/neuropilin, coincided with expression of their ligands, being maximally expressed during mineralization. VEGF-A production during osteoblast differentiation was stimulated by insulin-like growth factor I that enhances osteoblast differentiation and was inhibited by PTH-related peptide that inhibits osteoblast differentiation. Furthermore, continuous treatment of KS483 cells with recombinant human VEGF-A stimulated nodule formation. Although treatment of KS483 cells with soluble FLT1, an agent that blocks binding of VEGF-A and -B to VEGFR1, did not inhibit nodule formation, this observation does not exclude involvement of VEGFR2 in the regulation of osteoblast differentiation. As it is known that VEGF-A, -C, and -D can act through activation of VEGFR2, other isoforms might compensate for VEGF-A loss. The expression pattern of VEGFs and their receptors shown here suggests that VEGFs play an important role in the regulation of bone remodeling by attracting endothelial cells and osteoclasts and by stimulating osteoblast differentiation.
    Endocrinology 05/2000; 141:1667--1674. · 4.72 Impact Factor
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    ABSTRACT: Nitric oxide (NO) is a mediator of bone metabolism with effects on both bone resorption and formation. Its production by both the constitutive and inducible isoforms of nitric oxide synthase (NOS) is affected by oestrogen in several types of cell and in tissues other than bone cells. Recently, oestrogens were found to increase basal NO production by osteoblasts via enhanced activity or expression, or both, of NOS-3. Inflammatory cytokines, however, increase NO by increasing the expression of NOS-2. In this study we have examined whether cytokine-induced NO production by osteoblastic cells was affected by oestrogenic compounds by studying the effect of 17beta-oestradiol and the anti-oestrogens ICI164,384 and 4-hydroxytamoxifen on cytokine-induced NO production in oestrogen receptor positive MC3T3-E1 osteoblast-like cells. Combinations of the inflammatory cytokines interleukin-1beta, tumour necrosis factor-alpha, and interferon-gamma with lipopolysaccharide stimulated NO production up to 11-fold. This cytokine-induced NO production was further increased dose-dependently by the anti-oestrogens ICI164,384 and 4-hydroxytamoxifen (133.3 +/- 3.2% and 146.0 +/- 13.2%, respectively). 17Beta-oestradiol either had no effect on or slightly inhibited cytokine-induced NO production. It did, however, dose-dependently counteract the stimulatory effect of the anti-oestrogens. Concentrations of 17beta-oestradiol needed to prevent the stimulatory effect of 4-hydroxytamoxifen were ca tenfold that of ICI164,384. These findings show that, in addition to the stimulatory effect of oestrogen on basal NO production by NOS-3, cytokine-induced NO production is also affected by oestrogenic compounds in osteoblasts.
    Journal of Pharmacy and Pharmacology 01/2000; 51(12):1409-14. · 2.03 Impact Factor