Outi Saijonmaa

Corticotrophin-releasing factor in human placenta: Localization, concentration and release in vitro

Corticotrophin-releasing factor (CRF) immunoreactivity was demonstrated by immunohistochemical staining in the cytotrophoblast of the early pregnancy placenta, in the decidua and in the amnion. This localization is different from that of adrenocorticotrophic hormone (ACTH) and beta-endorphin, which are present in the syncytiotrophoblast. The release of immunoreactive CRF was demonstrated from both early and term placental tissues in vitro. The mean amounts of CRF in the early and term pregnancy placental/decidual extracts were 0.99 +/- 0.5 ng/g and 19.7 +/- 3.1 ng/g, respectively. A slightly greater amount of CRF was found in extracts from term placentae and in cord venous plasma collected after spontaneous vaginal delivery than in those collected at elective caesarean section performed before the beginning of labour.

Telomere length and cardiovascular risk in hypertensive patients with left ventricular hypertrophy: the LIFE study

Short telomeres are associated with aging and age-related diseases. Our aim was to determine whether short leukocyte telomere length is associated with risk factors and cardiovascular diseases in a high-risk hypertensive population. We measured leukocyte telomere lengths at recruitment in 1271 subjects with hypertension and left ventricular hypertrophy (LVH) participating in the Lifestyle Interventions and Independence for Elders (LIFE) study. At baseline, short mean telomere length was associated with coronary artery disease in males (odds ratio (OR) 0.61, 95% confidence interval (CI) 0.39–0.95), and transient ischemic attack in females (OR 0.62 95% CI 0.39–0.99). Proportion of short telomeres (shorter than 5u2009kb) was associated with Framingham risk score (r=0.07, P<0.05), cerebrovascular disease (OR 1.18, 95% CI 1.01–1.15) and type 2 diabetes in men (OR 1.07, 95% CI 1.02–1.11). During follow-up, proportion of short telomeres was associated with combined cardiovascular mortality, stroke or angina pectoris (hazard ratio 1.04, 95% CI 1.01–1.07). Telomere length was not associated with smoking, body mass index, pulse pressure or self-reported use of alcohol. Our data suggest that reduced leukocyte telomere length is associated with cardiovascular risk factors and diseases as well as type 2 diabetes, and is a predictor of cardiovascular disease in elderly patients with hypertension and LVH.

Telomere length and cardiovascular aging

Telomeres are located at the end of chromosomes. They are composed of repetitive TTAGGG tandem repeats and associated proteins of crucial importance for telomere function. Telomeric DNA is shortened by each cell division until a critical length is achieved and the cell enters senescence and eventually apoptosis. Telomeres are therefore considered a ‘biological clock’ of the cell. Telomerase adds nucleotides to telomeric DNA thereby contributing to telomere maintenance, genomic stability, functions, and proliferative capacity of the cell. In certain rare forms of progeria, point mutations within the telomere lead to accelerated telomere attrition and premature aging. Endogenous factors causing telomere shortening are aging, inflammation, and oxidative stress. Leukocyte telomere length (LTL) shortening is inhibited by estrogen and endogenous antioxidants. Accelerated telomere attrition is associated with cardiovascular risk factors such as age, gender, obesity, smoking, sedentary life-style, excess alcohol intake, and even mental stress. Cardiovascular (CV) diseases and CV aging are usually but not invariably associated with shorter telomeres than in healthy subjects. LTL appears to be a biomarker of CV aging, reflecting the cumulative burden of endogenous and exogenous factors negatively affecting LTL. Whether accelerated telomere shortening is cause or consequence of CV aging and disease is not clear.

Insulin increases the release of endothelin in endothelial cell cultures in vitro but not in vivo

Endothelin-1 (ET-1), a potent vasoconstrictor and mitogenic peptide for vascular smooth muscle cells, may be a marker for development of vascular disorders in diabetic patients. The aim of this study was to elucidate the possible role of insulin in the regulation of ET-1 production. The effect of hyperinsulinemia (with and without concomitant hyperglycemia) on the release of ET-1 was studied in 23 healthy men in vivo, as well as in human umbilical cord vein endothelial cell (HUVEC) cultures in vitro. Plasma glucose and insulin were maintained at four desired levels (from 5 to 22 mmol/L and 0.065 to 12.9 nmol/L, respectively) during the in vivo studies. The mean (SEM) plasma ET-1 during normoglycemia and a fasting insulin concentration in healthy men was 3.8 (0.4) pg/mL, and ET-1 levels did not change in response to changes in the concentration of glucose (from 5.0 to 22 mmol/L) or insulin (from 0.065 to 12.9 nmol/L). The ET-1 concentration in HUVEC culture medium increased linearly during 24 hours, and insulin further enhanced the release of ET-1 dose-dependently. ET-1 release was stimulated by angiotensin II, thrombin, and transforming growth factor-beta (TGF-beta), whereas treatment with glucose and insulin-like growth factor-1 (IGF-1) was not associated with changed ET-1 levels in culture medium. Our results show that although high insulin concentrations stimulate ET-1 release in vitro, hyperinsulinemia is not associated with increased plasma ET-1 levels in healthy men in vivo. The role of insulin in the regulation of ET-1 production in vivo, if any, remains unsettled.

Upregulation of angiotensin converting enzyme by atrial natriuretic peptide and cyclic GMP in human endothelial cells

OBJECTIVEnTo examine the role of atrial natriuretic peptide (ANP) and cyclic GMP in the regulation of angiotensin converting enzyme (ACE) in cultured human endothelial cells.nnnMETHODSnCultured endothelial cells from human umbilical veins (HUVEC) were treated with ANP (0.3-30 nM), 8-Br-cGMP (1-100 microM), Rp-8-Br-PET-cGMPS (1 microM), or the phosphodiesterase inhibitors, zaprinast (10-100 microM), dipyridamole (1-10 microM), or isobutyl methyl xanthine (IBMX, 0.1-0.5 mM). ACE amounts were measured by inhibitor binding assay and cellular cGMP levels by radioimmunoassay.nnnRESULTSnANP caused a dose dependent increase in ACE measured in intact endothelial cell culture. The stimulatory effect of ANP was blocked by Rp-8-Br-PET-cGMPS, a protein kinase G inhibitor. The cyclic GMP analog, 8-Br-cGMP and the cyclic GMP specific phosphodiesterase inhibitor, zaprinast, both increased ACE. Increase of ACE was also caused by nonspecific phosphodiesterase inhibitors, dipyridamole and IBMX. Intracellular cGMP levels were shown to increase by ANP, and phosphodiesterase inhibitors.nnnCONCLUSIONSnThese data suggest that cGMP is an intracellular mediator regulating ACE and that ANP induced increase of ACE is mediated via a cGMP dependent mechanism.

Localization and ceoncentration of β- and β-lipotrophin in human placenta

Abstract Immunohistochemical staining of placental tissue for β-endorphin immunoreactivity was positive in the syncytiotrophoblast in both early and term pregnancy. Cation-exchange liquid chromatography and radioimmunoassay revealed peaks of β-endorphin and β-lipotrophin and a third immunoreactive peak of unknown nature. The concentration of β-endorphin was higher in the placental tissue than it was in the maternal or cord plasma. β-Lipotrophin was not detected in all placentae studied. We did not find any effect of gestational age on tissue concentrations of endorphins in the placenta, nor was there any significant difference in the placental endorphin content between placentae collected at elective caesarean section before labour and after spontaneous vaginal delivery.

Telomere length is associated with ACE I/D polymorphism in hypertensive patients with left ventricular hypertrophy

Introduction: Short telomeres are often associated with cardiovascular risk factors and age-related diseases, while the angiotensin converting enzyme (ACE) gene insertion/deletion polymorphism (DD, ID, II) has shown such associations less consistently. We hypothesized that telomere length and association of telomere length with cardiovascular risk is affected by ACE (I/D) genotype. Methods: We measured leucocyte telomere length (LTL) by Southern blot and analysed ACE I/D genotypes in 1249 subjects with hypertension and left ventricular hypertrophy (LVH). We examined interactions of ACE I/D genotype with LTL and cardiovascular risk. Results: Mean LTL in DD or ID genotype was shorter (8.15 and 8.14 kb, respectively), than in II genotype (8.27 kb, p=0.0005). This difference was significant in the younger subjects (55–64 years, p=0.02) but not in the older group (65–80 years, p=0.56 ). In DD but not I/D or II genotype, proportion of short telomeres (<5 kb) was related to Framingham risk score. Conclusions: Shorter LTL in genotypes DD or ID suggests a negative effect of the D allele on telomere length. Homozygocity for the D allele appears to strengthen the association of telomere length with increased cardiovascular risk in elderly hypertensive subjects with LVH.