Biomedical subjects

B Halvorsen

Publications and source records attributed to B Halvorsen.

At least 19 recordsLinked to original sources

PubMed2006

Activin A inhibits organization of sarcomeric proteins in cardiomyocytes induced by leukemia inhibitory factor.

Cytokine systems are activated in heart failure, and it is believed that interaction between such systems may be important during progression of this disorder. We have previously shown that failing hearts have increased levels of the interleukin-6 related cytokine leukemia inhibitory factor (LIF) and activin A, a member of the transforming growth factor-beta family. The aim of this study was to examine the effects of activin A on cardiomyocytes and a potential interaction with LIF-mediated changes in cell signaling and growth. Cardiomyocytes were isolated from 1- to 3-day-old Wistar rats, and the cells were treated with LIF, activin A or a combination thereof. Our main findings were: (i) activin A treatment reduced the LIF-mediated increase in cardiomyocyte length, perimeter and sarcomeric organization and was accompanied by a substantially decreased alpha-skeletal actin gene expression. (ii) The activin A-mediated phosphorylation of Smad2 was markedly enhanced by LIF. (iii) Activin A markedly induced SOCS3 gene expression, while LIF potently increased the expression of Smad7 mRNA, representing inhibitors of LIF and activin A signaling pathways, respectively. (iv) Inhibiting activation of the Smad2/3 pathway abolished the effects of activin A on LIF-induced changes in cell length, perimeter and sarcomeric organization. In conclusion, activin A markedly attenuates LIF-induced changes in cardiomyocytes, reflecting a potentially important role for both activin A and the Smad2/3 pathway in regulation of myocardial remodeling.

Activins↗

PubMed2005

Altered composition of HDL3 in FH subjects causing a HDL subfraction with less atheroprotective function.

BACKGROUND: Subjects with familial hypercholesterolemia (FH) are associated with increased risk of premature atherosclerosis and coronary artery disease (CAD). However, onset of clinically manifested CAD varies widely among subjects with heterozygous FH. The purpose of this study was to investigate whether FH subjects with an identical mutation in the low-density lipoprotein (LDL) receptor gene have a high-density lipoprotein (HDL)3 that is characterized by a less atheroprotective functions than that of healthy controls and within subgroups of FH. DESIGN: Twenty-two adults <75 years of age with FH and 17 healthy sex- and age-matched controls were included. HDL3 was isolated and the composition was characterized from each subject, and its ability to suppress tumor necrosis factor(TNF)-alpha stimulated expression of ICAM-1 on HUVEC was investigated. In addition, plasma level of soluble sICAM-1 and VCAM-1 was measured. RESULTS: Compared to controls, FH subjects had lower content of phospholipids in their HDL3 subfraction and a higher serum ICAM-1 level. No differences in sVCAM-1 were observed. HDL3 isolated from FH with body mass index(BMI)>25 and from FH subjects with premature CAD contained higher content of triglycerides compared to the HDL3 from FH subjects with BMI<25 and without CAD, respectively. Most important, when testing the function of HDL3 in the two FH subgroups characterized by elevated BMI and premature CAD, lower inhibition of ICAM-1 expression on HUVEC was observed. CONCLUSIONS: The altered composition of HDL3 from FH subjects with BMI>25 and FH subjects with premature CAD may be responsible for a HDL3 subfraction with less protective properties assessed as inhibition of ICAM-1 expression on HUVEC consequently leading to more proatherogenic endothelial surface.

Adult↗

PubMed2005

Increased expression of chemokines in patients with Wegener's granulomatosis - modulating effects of methylprednisolone in vitro.

Chemokines, a group of cytokines that attracts and activates leucocyte subpopulations in inflamed tissue, have been associated with the pathogenesis of a number of inflammatory diseases, and some recent reports have suggested their involvement in Wegener's granulomatosis (WG). To elucidate further the possible role of chemokines in WG we examined serum levels of several CC- and CXC-chemokines in WG patients and assessed the ability of corticosteroids to modulate the expression of these mediators in vitro. Our main findings were: (i) WG patients (n = 14) had elevated serum levels of several inflammatory chemokines [i.e. regulated upon activation normal T cell expressed and secreted (RANTES), monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-8] compared to healthy controls (n = 9), as assessed by enzyme immunoassays (EIAs); (ii) by using EIAs and real-time reverse transcription-polymerase chain reaction (RT-PCR), we demonstrated the ability of methylprednisolone (MP) to down-regulate both the spontaneous and the staphylococcal enterotoxin B (SEB)-induced release of chemokines from peripheral blood mononuclear cells (PBMC) in vitro in both WG patients and controls, possibly involving both transcriptional and post-transcriptional mechanisms; and (iii) the ability of MP to attenuate chemokine secretion was less pronounced in WG patients than in controls, particularly with regard to inhibition of spontaneous release. Our findings suggest a role for chemokines in the pathogenesis of WG. The diminished MP-mediated suppression of chemokines in PBMC from WG patients suggests that more specific modulators of chemokine levels should be investigated in this disorder.

Adult↗

PubMed2004

8-isoprostane increases scavenger receptor A and matrix metalloproteinase activity in THP-1 macrophages, resulting in long-lived foam cells.

BACKGROUND: Oxidative stress is a key factor in atherogenesis, in which it is closely associated with the inflammation and formation of bioactive lipids. Although 8-isoprostane is regarded as a reliable marker of oxidative stress in vivo, the pathogenic role of this F(2)-isoprostane in atherogenesis is far from clear. Based on the important role of foam cells in the initiation and progression of atherosclerosis we hereby examined the ability of 8-isoprostane to modulate oxidized (ox)LDL-induced foam cell formation and the function of these cells, particularly focusing on the effect on matrix degradation. METHODS AND RESULTS: 8-isoprostane (10 micro M) augmented the oxLDL-induced (20 micro g mL(-1)) lipid accumulation of THP-1 macrophages evaluated by Oil-Red-O staining and lipid mass quantification (colourimetric assay). Additionally, 8-isoprostane induced the expression of the scavenger receptor A type 1 (MSR-1) [mRNA and protein level], assessed by RT-PCR and Western blotting, respectively. Moreover, 8-isoprostane counteracted the oxLDL-induced apoptosis of these cells, involving both mitochondrial-protective and caspase-suppressive mechanisms. Along with these changes, 8-isoprostane increased the oxLDL-induced gene expression of matrix metalloproteinase (MMP)-9 and its endogenous inhibitor [i.e. tissue inhibitor of MMP (TIMP)-1] accompanied by enhanced total MMP activity. CONCLUSIONS: We show that 8-isoprostane increases foam cell formation at least partly by enhancing MSR-1 expression and by inhibiting apoptosis of these cells, inducing long-lived foam cells with enhanced matrix degrading capacity. Our findings further support a role for 8-isoprostane not only as a marker of oxidative stress in patients with atherosclerotic disorders, but also as a mediator in atherogenesis and plaque destabilization.

Apoptosis↗

PubMed2004

Increased myocardial matrix metalloproteinases in hypoxic newborn pigs during resuscitation: effects of oxygen and carbon dioxide.

BACKGROUND: Perinatal asphyxia is associated with cardiac dysfunction, and it is important to prevent further tissue injury during resuscitation. There is increasing evidence that myocardial matrix metalloproteinases (MMPs) are involved in myocardial hypoxaemia-reoxygenation injury. OBJECTIVE: To assess MMPs and antioxidant capacity in newborn pigs after global ischaemia and subsequent resuscitation with ambient air or 100% O(2) at different PaCO(2)-levels. METHODS: Newborn pigs (12-36 h of age) were resuscitated for 30 min by ventilation with 21% or 100% O(2) at different PaCO(2) levels after a hypoxic insult, and thereafter observed for 150 min. In myocardial tissue extracts, MMPs were analyzed by gelatin zymography and broad matrix-degrading capacity (total MMP). Total endogenous antioxidant capacity in myocardial tissue extracts was measured by the oxygen radical absorbance capacity (ORAC) assay. RESULTS: Matrix metalloproteinase-2 more than doubled from baseline values (P < 0.001), and was higher in piglets resuscitated with 100% O(2) than with ambient air (P = 0.012). The ORAC value was considerably decreased (P < 0.001). In piglets with elevated PaCO(2), total MMP-activity in the right ventricle was more increased than in the left ventricle (P = 0.008). In the left ventricle, total MMPactivity was higher in the piglets with low PaCO(2) than in the piglets with elevated PaCO(2) (P = 0.013). CONCLUSION: In hypoxaemia-reoxygenation injury the MMP-2 level was highly increased and was most elevated in the piglets resuscitated with 100% O(2). Antioxidant capacity was considerably decreased. Assessed by total MMP-activity, elevated PaCO(2) during resuscitation might protect the left ventricle, and probably increase right ventricle injury of the myocardium.

Animals↗

PubMed2004

Lipid-lowering and anti-inflammatory effects of tetradecylthioacetic acid in HIV-infected patients on highly active antiretroviral therapy.

BACKGROUND: Highly active antiretroviral therapy (HAART) often leads to a dramatic improvement in clinical, viral and immunologic parameters in HIV-infected individuals. However, the emergence of long-term side-effects of HAART and in particular dylipidaemia is increasingly reported. Based on the potential lipid-lowering and immunomodulatory properties of tetradecylthioacetic acid (TTA) we examined whether TTA in combination with dietary intervention could modify lipid levels in peripheral blood in HIV-infected patients on HAART. MATERIALS AND METHODS: Ten HIV-infected patients on protease inhibitor-based HAART with hyperlipidaemia followed a cholesterol-lowering diet throughout the study period (8 weeks). During the last 4 weeks of the study all patients received TTA (1 g qd) in addition to the cholesterol-lowering diet. RESULTS: Our main and novel findings were: (i) TTA in combination with dietary intervention reduces total cholesterol, LDL cholesterol, triglycerides and LDL/HDL cholesterol in these patients, and a particularly suppressing effect was observed during the TTA phase regarding total cholesterol. (ii) During the TTA phase, the cholesterol-lowering effect was accompanied by a significant reduction in plasma levels of tumour necrosis factor alpha. (iii) Our studies in peripheral blood mononuclear cells from these patients and in the liver from wild-type mice receiving TTA suggest that the hypolipidaemic effects of TTA may involve up-regulation of scavenger and LDL-receptor expression. CONCLUSIONS: Although few patients were studied, the present pilot study suggests that TTA combined with dietary intervention could be an interesting therapeutic approach in HIV-infected patients on HAART, potentially resulting in both hypolipidaemic and anti-inflammatory effects.

Adult↗

PubMed2004

Expression of matrix metalloproteinases in patients with Wegener's granulomatosis.

BACKGROUND: Enhanced activity of matrix metalloproteinases (MMPs) has been reported to have a pathogenic role in several diseases such as cancer and cardiovascular disorders, and seems also to play a part in certain autoimmune diseases. OBJECTIVE: To examine whether enhanced MMP activity may also have a role in the pathogenesis of Wegener's granulomatosis (WG). METHODS: In a study group of 15 patients with WG and 15 controls, plasma levels and gene expression were measured in freshly isolated peripheral blood mononuclear cells (PBMCs) of several MMPs and their endogenous inhibitors (that is, tissue inhibitors of metalloproteinases (TIMPs)) by enzyme immunoassays and RNase protection assay, respectively. RESULTS: Whereas patients with WG in remission had enhanced gene expression of several MMPs and TIMPs in PBMCs, those with active disease had a selective up regulation of MMP-2 and MMP-8 compared with healthy controls, and a down regulation of TIMP-1 and TIMP-3 compared with other patients with WG. Moreover, plasma levels of TIMP-1 and MMP-8 correlated significantly with C reactive protein levels, further supporting an association between activation of the MMP/TIMP system and disease activity in WG. Finally, these changes in MMP/TIMP expression in WG were accompanied by increased total MMP activity in PBMC supernatants, particularly in those with active disease, suggesting a matrix degrading net effect. CONCLUSION: These findings suggest that disturbed MMP and TIMP activity has a role in the pathogenesis of WG.

Adult↗

PubMed2003

Augmented PLA2 activity in pre-eclamptic decidual tissue--a key player in the pathophysiology of 'acute atherosis' in pre-eclampsia?

Decidual acute atherosis is associated with pre-eclampsia, but the underlying mechanism is still unclear. We have previously demonstrated elevated level of the oxidative stress marker 8-isoprostaglandin F(2 alpha)(8-isoprostane) and lipids in pre-eclamptic decidual tissue. Arachidonic acid (AA) in tissue phospholipids is a source for 8-isoprostane generation, and 8-isoprostane is liberated from tissue phospholipids by phospholipase A(2)(PLA(2)). The aims of this study were to explore whether AA content or PLA(2)expression in pre-eclamptic decidual tissue differed from controls. Decidua basalis tissues were obtained by vacuum aspiration at Caesarean delivery in pre-eclamptic and control pregnancies. We demonstrated a statistically significantly higher total PLA(2)activity in pre-eclamptic decidua compared to control tissue. On the other hand, no differences in AA content of tissue phospholipids or protein expression of secretory and cytosolic PLA(2)between pre-eclamptic and control decidual tissue were found. In conclusion, the elevated level of free 8-isoprostane in pre-eclamptic decidual tissue could be caused by augmented PLA(2)activity. We speculate that an elevated PLA(2)enzyme activity in pre-eclamptic decidual tissue could be of importance in the pathogenesis of 'acute atherosis', comparable to the atherogenesis in cardiovascular diseases.

Apolipoproteins B↗

PubMed2003

Expression of matrix metalloproteinase-9 in mononuclear cells of hyperhomocysteinaemic subjects.

Atherosclerotic plaque instability and rupture requires extracellular matrix modification, a complex process regulated by matrix metalloproteinases (MMPs). We hypothesized that homocysteine's atherogenic effects may involve MMP-mediated mechanisms. Our results showed the following: (i) Compared with healthy control subjects (n = 9), patients with hyperhomocysteinaemia (n = 9) had elevated mRNA levels of MMP-9 and tissue inhibitors of metalloproteinases-1 (TIMP-1) in freshly isolated peripheral blood mononuclear cells (PBMCs), which were positively correlated with homocysteine and negatively correlated with folate and vitamin B12 levels. (ii) Peripheral blood mononuclear cells obtained from these patients released markedly enhanced the amount of MMP-9 upon oxidized LDL (oxLDL) stimulation, whereas no such enhancing effect was seen in cells from healthy controls. (iii) During folic acid 6 weeks' treatment, normalization of homocysteine levels was accompanied by a significant reduction in mRNA levels of MMP-9 and TIMP-1 in PBMCs, as well as a marked reduction in oxLDL-stimulated release of MMP enzyme activity. These novel findings may suggest that homocysteine exerts its atherogenic effect in part by elevating levels and activity of MMPs, which in turn may enhance matrix degradation, potentially promoting atherogenesis and plaque instability. Moreover, our findings suggest that folic acid supplementation may down-regulate these inappropriate responses in these patients.

Female↗

PubMed2002

Inflammatory imbalance between IL-10 and TNFalpha in unstable angina potential plaque stabilizing effects of IL-10.

BACKGROUND: The pathogenesis of atherosclerosis and acute coronary syndromes involves inflammation and immunological mechanisms. We hypothesized that patients with unstable angina may have an imbalance between inflammatory and anti-inflammatory cytokines. DESIGN: Plasma levels of tumour necrosis factor (TNF)alpha and interleukin (IL)-10 were analyzed in 44 patients with stable angina, 29 patients with unstable angina and 20 controls. mRNA levels of these cytokines were analyzed in peripheral blood mononuclear cells (PBMC). We also studied the in vitro effects of IL-10 in PBMC from unstable angina patients. RESULTS: Our main findings were: (1) the angina patients and particularly those with unstable disease had significantly raised TNFalpha in comparison with the controls, both at the protein and mRNA level; (2) in contrast, the levels of IL-10 were not different in the angina patients in comparison with the healthy controls, resulting in a markedly enhanced TNFalpha:IL-10 ratio, particularly in the unstable angina patients; (3) while exogenously added IL-10 markedly inhibited the release of TNFalpha, IL-8 and tissue factor as well as impairing the gelatinolytic activity and mRNA production of matrix metalloproteinase-9, it enhanced the tissue inhibitor of this metalloproteinase (i.e. TIMP-1) in PBMC from the unstable angina patients. CONCLUSION: Patients with unstable angina appear to have an imbalance between TNFalpha and IL-10, possibly favouring inflammatory net effects. IL-10 may have beneficial effects on mechanisms that are important in plaque rupture and thrombus formation.

Adult↗

PubMed2001

Effects of long-chain monounsaturated and n-3 fatty acids on fatty acid oxidation and lipid composition in rats.

Long-chain n-3 fatty acids and fat fish are reported, among multiple physiological properties, to enhance peroxisomal beta-oxidation and effect triacylglycerol status. Long-chain n-3 and monounsaturated fatty acids are the main portion of fatty acids in fat fish. The individual effect of long-chain monounsaturated fatty acids on beta-oxidation and fatty acid composition was tested and compared to the effect of n-3 polyunsaturated and saturated fatty acids in a 3-week feeding experiment of rats. To explore the contribution from long-chain monounsaturated fatty acids in these aspects, the effect of long-chain n-3 and monounsaturated fatty acids on mitochondrial and peroxisomal beta-oxidation was compared, as well as fatty acid composition of adipose tissue, liver and serum. Fatty acid oxidase, palmitoyltransferase I and II activities, the amount of serum lipids, and the fatty acid composition of lipid fractions from the organs were analysed. The peroxisomal beta-oxidation was enhanced by the n-3 fatty acids, whereas a small, significant increase with the monounsaturated fatty acids was observed. There was a stimulation of the mitochondrial oxidation with the n-3 fatty acids, but monounsaturated fatty acids gave a small, nonsignificant decrease. With n-3 fatty acids there was a considerable decrease in the levels of serum triacylglycerol, phospholipids, free fatty acids and total cholesterol, while there were only minor effects of monounsaturated fatty acids. As judged from the fatty acid composition data, there was a mobilization on n-3 fatty acids from the adipose tissue to liver and plasma with the n-3 diet. This observation was also seen with the monounsaturated fatty acid-enriched diet. In conclusion, monounsaturated fatty acids seemed to stimulate peroxisomal beta-oxidation and to increase plasma triacylglycerol, whereas the mitochondrial oxidation was slightly decreased.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed2001

8-iso-prostaglandin F(2alpha) increases expression of LOX-1 in JAR cells.

Lectinlike oxidized LDL receptor-1 (LOX-1), a cell-surface receptor for oxidized LDL (ox-LDL), is proposed to be involved in endothelial dysfunction and in the pathogenesis of atherosclerosis. Preeclampsia is a pregnancy complication diagnosed by hypertension and proteinuria, characterized by endothelial dysfunction, and supposedly caused by compounds from hypoxic uteroplacental tissues. A feature of preeclampsia is formation of foam cells in maternal arterial walls of gestational tissue ("acute atherosis"). Oxidative stress is believed to play a role in the pathophysiology of preeclampsia. 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) is a marker of oxidative stress in vivo, is biologically active in vitro, and is elevated in preeclamptic plasma and gestational tissue. In the present article, we hypothesized that 8-iso-PGF(2alpha) could induce the expression of LOX-1 in trophoblastic cells (JAR). We demonstrated augmented cellular uptake of (125)I-tyraminylcellobiose ox-LDL in JAR cells incubated with 8-iso-PGF(2alpha) (10 micromol/L) versus control cells. Ligand blots revealed an increased binding of ox-LDL to LOX-1 in JAR cells incubated with 8-iso-PGF(2alpha) (10 micromol/L). Incubation with 8-iso-PGF(2alpha) (10 micromol/L) also resulted in augmented LOX-1 protein levels (Western blots) and mRNA levels (Northern blots). JAR cells transfected with 3 copies of a nuclear factor-kappaB binding site demonstrated dose-dependent activation of the reporter gene luciferase after incubation with 8-iso-PGF(2alpha) (0 to 10 micromol/L). We also demonstrated increased accumulation of neutral fats in JAR cells incubated with 8-iso-PGF(2alpha) (10 micromol/L) and ox-LDL compared with controls by oil red O staining. We speculate a potential role of isoprostanes and LOX-1 in preeclampsia in the development of "acute atherosis" of gestational spiral arteries.

Azo Compounds↗

PubMed2001

Reduction of leptin gene expression by dietary polyunsaturated fatty acids.

Supplementation with n-3 polyunsaturated fatty acids (PUFA) for 6 weeks did not alter plasma leptin concentrations in male smokers. Changes in dietary intake of saturated fatty acids (FA) correlated positively, whereas changes in the intake of PUFA correlated negatively to changes in plasma leptin levels. A 3-week n-3 PUFA-enriched diet, as compared with a 3-week lard-enriched diet, induced lower plasma leptin concentration and reduced leptin mRNA expression in rat epididymal adipose tissue. In the human trophoblast cell line (BeWo), n-3 PUFA had a dose- and time-dependent effect on leptin expression. One mM of eicosapentaenoic acid or docosahexaenoic acid (DHA) reduced leptin expression by 71% and 78%, respectively, as compared with control, after 72 h. There was no effect on expression of the signal transducing form of the leptin receptor. In BeWo cells transfected with the human leptin promoter, we found that n-3 PUFA reduced leptin promoter activity; in contrast saturated and monounsaturated FA had no effect on leptin promoter activity. The transcription factors peroxysomal proliferator activated receptor gamma and sterol regulatory element binding protein-1 mRNAs were reduced after incubation with n-3 PUFA, whereas the expression of CCAAT/enhancer binding protein alpha was unchanged. DHA-reduced leptin expression was abolished in BeWo cells grown in cholesterol-free medium. In conclusion, n-3 FA decreased leptin gene expression both in vivo and in vitro. The direct effects of PUFA on leptin promoter activity indicate a specific regulatory action of FA on leptin expression.

Adipose Tissue↗

PubMed2000

Lithocholic acid and sulphated lithocholic acid differ in the ability to promote matrix metalloproteinase secretion in the human colon cancer cell line CaCo-2.

The human colon carcinoma cell line CaCo-2 has the ability to sulphate the secondary bile acid lithocholic acid (LA), whereas other primary or secondary bile acids were not sulphated [Halvorsen, Kase, Prydz, Gharagozlian, Andresen and Kolset (1999) Biochem. J. 343, 533--539]. To study the biological implications of this modification, CaCo-2 cells were incubated with either LA or sulphated lithocholic acid (3-sulpholithocholic acid, SLA), and in some experiments with taurine-conjugated lithocholic acid. Increased secretion of matrix metalloproteinases (MMPs) correlates with transformation of colon epithelial cells. When CaCo-2 cells were incubated with LA, the secretion of MMP-2 was found to increase approx. 60% when analysed by gelatin zymography, and 80% when analysed by Western blotting. SLA, in contrast, did not affect the level of MMP-2 secretion, and after zymography the level of enzyme activity was 78% of control values after 18 h incubation. The secretion of MMPs is linked to increased cellular invasion and, in tumours, to increased capacity for metastasis. The ability of CaCo-2 cells to invade in a chamber assay was stimulated after exposure to LA, whereas SLA-treated cells did not differ from control cells. LA therefore seems to induce a more invasive CaCo-2 cell phenotype, as judged by the two parameters tested, whereas the sulphated counterpart, SLA, did not have these effects. Sulphation of LA in the colon may be an important mechanism to decrease the potential LA has to promote a malignant epithelial phenotype.

Bile Acids and Salts↗

PubMed2000

8-Iso-prostaglandin f(2alpha) reduces trophoblast invasion and matrix metalloproteinase activity.

Preeclampsia is a common pregnancy complication in the latter half of gestation diagnosed by hypertension and proteinuria. A key feature of preeclampsia is an altered placentation with reduced trophoblast invasion. Normal placentation requires controlled invasion of trophoblasts into the maternal uterine wall, with secretion of specific proteolytic enzymes able to degrade basement membranes and extracellular matrix, such as the matrix metalloproteinases (MMPs). 8-Iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) is a marker of oxidative stress in vivo and is biologically active. We have recently reported an elevated content of free 8-iso-PGF(2alpha) in preeclamptic gestational tissue at delivery. Assuming an elevated level of 8-iso-PGF(2alpha) during the invasion period of the pregnancy, we hypothesized that 8-iso-PGF(2alpha) could reduce invasion of JAR cells, a choriocarcinoma cell line. We investigated JAR cell invasion with 2 types of Transwell assays and demonstrated that 8-iso-PGF(2alpha) (10 micromol/L) resulted in reduced cell invasion in both the colorimetric and radioactivity Transwell assays (P<0.01). Zymograms revealed reduced MMP-2 and MMP-9 activity in conditioned media from JAR cells incubated with 8-iso-PGF(2alpha) (10 micromol/L) (P<0.02). 8-Iso-PGF(2alpha) (10 micromol/L) also reduced the collagenase type IV activity in the conditioned media of JAR cells (P=0.04). No effects on MMP-2 and MMP-9 mRNA levels were observed after incubation with 8-iso-PGF(2alpha) (10 micromol/L), whereas protein levels were significantly decreased (P<0.02), suggesting a posttranscriptional regulation. We hypothesize a potential role for 8-iso-PGF(2alpha) in the reduced trophoblast invasion in preeclampsia.

Blotting, Western↗

PubMed1999

Sulphation of lithocholic acid in the colon-carcinoma cell line CaCo-2.

High levels of bile acids in the colon may correlate with an increased risk of colon cancer, but the underlying mechanisms are not known. Proteoglycan structures have been shown to change when human colon cells differentiate in vitro. The expression of [(35)S]sulphated molecules was used as a phenotypic marker to study the effects of bile acids on the human-colon-carcinoma cell line CaCo-2. [(35)S]sulphated compounds were isolated from the medium of cell fractions of cells metabolically labelled with [(35)S]sulphate in the absence and presence of cholic acid, deoxycholic acid, chenodeoxycholic acid and lithocholic acid (LA). Labelled molecules were analysed by gel chromatography, HPLC and SDS/PAGE in combination with chemical and enzymic methods. The expression of (35)S-labelled proteoglycans was not affected by any of the bile acids tested. However, the level of sulphated metabolites increased 7-18-fold in different experiments during a 22 h labelling period in the presence of an LA concentration of 10 microg/ml (26.6 nmol/ml) compared with controls. Further analyses showed that this was due, at least in part, to the sulphation of LA itself. This sulphation of LA was a rapid process followed by secretion back to the medium. Brefeldin A did not reduce the sulphation of LA, indicating that this conversion takes place in the cytosol, rather than in the Golgi apparatus of the CaCo-2 cells. LA in colon may be sulphated efficiently by the colonocytes to reduce the toxic effects of this particular bile acid. Sulphation may possibly be an important protective mechanism in the colon.

Bile Acids and Salts↗

PubMed1999

Elevated level of free 8-iso-prostaglandin F2alpha in the decidua basalis of women with preeclampsia.

OBJECTIVES: The prostaglandin-like compound 8-iso-prostaglandin F(2alpha) represents an index of oxidative stress and has the ability to induce endothelial derangement, platelet activation, and vasoconstriction. In women with preeclampsia the decidual spiral arteries contain lipid deposits (acute atherosis). Analogously to the elevated level of 8-iso-prostaglandin F(2alpha) demonstrated in atherosclerotic lesions, we hypothesized that 8-iso-prostaglandin F(2alpha) level would be elevated in preeclamptic decidua basalis tissues. STUDY DESIGN: Decidua basalis tissues were obtained by vacuum aspiration and placental tissues were obtained by excision at cesarean delivery from 16 preeclamptic and 15 normal pregnancies. Total and free 8-iso-prostaglandin F(2alpha) concentrations were quantified with an enzyme immunoassay technique after lipid extraction and separation. RESULTS: The content of free 8-iso-prostaglandin F(2alpha) in preeclamptic decidual tissues was found to be significantly elevated with respect to that in control tissues. The content of total 8-iso-prostaglandin F(2alpha) did not differ significantly between the groups in either placenta or decidua basalis. CONCLUSIONS: We propose that free 8-iso-prostaglandin F(2alpha) released from the decidua basalis in preeclampsia may mediate maternal vascular dysfunction and platelet activation.

Adult↗

PubMed1999

Uptake of vitamin A in macrophages from physiologic transport proteins: role of retinol-binding protein and chylomicron remnants.

Vitamin A plays an important role in reducing infectious disease morbidity and mortality by enhancing immunity, an effect that is partly mediated by macrophages. Thus, knowing how these cells take up vitamin A is important. The results in the present study demonstrate that J774 macrophages efficiently take up chylomicron remnant retinyl esters and retinol-binding protein (retinol-RBP) bound retinol by specific and saturable mechanisms. The binding of (125)I-RBP to plasma membrane vesicles demonstrated that the macrophage receptor had a similar binding affinity, as was discovered previously for other cells. The B(max) for the macrophages was smaller than the values reported for placenta, bone marrow, and kidney, but larger than that reported for liver. The J774 cells also bound and took up [(3)H]retinol-RBP. Approximately 50 to 60% of the uptake may compete with excess unlabeled retinol-RBP and approximately 30 to 40% with excess transtyrethin. Following the uptake of [(3)H]retinol-RBP, an extensive esterification occurred: After 5 hours of incubation, 77.8 +/- 3.9% (SD; n = 3) of the cellular radioactivity was recovered as retinyl esters. The J774 cells also demonstrated saturable binding of chylomicron remnant [(3)H]retinyl esters, and a continuous uptake at 37 degrees C followed by an extensive hydrolysis of the retinyl esters. Binding could be inhibited by approximately 50% by excess unlabeled low density lipoprotein (LDL). In addition, lipoprotein lipase increased the binding of chylomicron remnant [(3)H]retinyl esters by approximately 30% and the uptake of chylomicron remnant [(3)H]retinyl ester by more than 300%. Furthermore, because sodium chlorate reduced binding with 40% and uptake with 55%, the results suggest that proteoglycans are involved in the uptake. Thus, the results suggest that both LDL receptor and LDL-related protein are involved in the uptake of chylomicron remnant [(3)H]retinyl ester in macrophages.

Journal Article↗