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Matti J Tikkanen

Publications and source records attributed to Matti J Tikkanen.

At least 19 recordsLinked to original sources
PubMed2006

Fatty acid esterification of lipoprotein-associated estrone in human plasma and follicular fluid.

Estrogen fatty acid esters constitute a unique family of extremely hydrophobic hormonal derivatives which are exclusively transported in lipoprotein particles in plasma. In estradiol, the fatty acyl residues are conjugated at the 17beta-hydroxyl of the steroid D-ring, leaving the phenolic 3-hydroxyl group unsubstituted and, therefore, preserving antioxidative efficacy. The 17beta-fatty acid derivative of estradiol is proposedly an even more efficient antioxidant protecting LDL and HDL than the parent steroid. Previous studies have established that the enzyme lecithin:cholesterol acyltransferase which catalyzes the fatty acid esterification of 3beta-hydroxyl group of cholesterol, also catalyzes the formation of estrogen 17beta-esters. Estrone, the principal estrogen in the postmenopausal female, has a keto group at carbon-17 and has been thought unable to form fatty acid esters. However, we detected hydrophobic derivatives of estrone following incubations with human plasma and ovarian follicular fluid. These derivatives accumulated in HDL and LDL during incubation showing chemical characteristics similar to estrone-3-fatty acid esters. Liquid chromatographic-mass spectrometric analyses established the presence of unhydrolyzed estrone esters consisting of different fatty acid species, the major one being estrone-3-linoleate, in human HDL particles following incubation of estrone with plasma. These extremely hydrophobic estrone conjugates could, in theory, represent a storage form of this estrogen.

Chromatography, Thin Layer↗
PubMed2005

Determination of plasma genistein fatty acid esters following administration of genistein or genistein 4'7-O-dioleate in monkeys.

Soy-derived isoflavone phytoestrogens, such as genistein (4',5,7-trihydroxyisoflavone), have been shown to protect low-density lipoprotein from oxidation. In addition, human plasma was previously shown to be capable of converting genistein into lipophilic fatty acid esters that accumulate in lipoproteins in vitro. We developed a method for the quantitation of genistein fatty acid esters in plasma. Furthermore, the method was utilized to measure genistein ester concentrations in monkey plasma following administration of genistein or genistein 4',7-O-dioleate. After extraction from plasma, genistein fatty acid esters were separated from unesterified genistein by Sephadex LH-20 column chromatography. The genistein ester fraction was hydrolyzed by saponification and purified by a second chromatography on Sephadex LH-20. The hydrolyzed genistein esters were measured by time-resolved fluoroimmunoassay. Adult female rhesus monkeys (n=10) received a subcutaneous injection of genistein (24 mg, n=2) or genistein 4',7-O-dioleate (71 mg, n=3) or an oral dose of genistein (24 mg, n=2) or genistein 4',7-O-dioleate (71 mg, n=3). Plasma was collected at 4, 8, and 24 h post-dosing. Following subcutaneous administration of genistein 4',7-O-dioleate, the plasma concentrations of genistein esters became elevated in two out of three monkeys with 8-h values exceeding 7.5 nmol/L and 24-h values above 12 nmol/L. Other treatments resulted in lower plasma values ranging between 2.7 and 6.1 nmol/L. The lower limit of detection for the method was 1.44 nmol/L. Subcutaneously administered genistein 4',7-O-dioleate was also converted to water-soluble conjugates, but oral administration did not elevate plasma genistein fatty acid ester levels. The results suggest that it may be possible to introduce intact genistein ester molecules into plasma by parenteral but not oral administration.

Administration, Oral↗
PubMed2005

High-dose atorvastatin vs usual-dose simvastatin for secondary prevention after myocardial infarction: the IDEAL study: a randomized controlled trial.

CONTEXT: Evidence suggests that more intensive lowering of low-density lipoprotein cholesterol (LDL-C) than is commonly applied clinically will provide further benefit in stable coronary artery disease. OBJECTIVE: To compare the effects of 2 strategies of lipid lowering on the risk of cardiovascular disease among patients with a previous myocardial infarction (MI). DESIGN, SETTING, AND PARTICIPANTS: The IDEAL study, a prospective, randomized, open-label, blinded end-point evaluation trial conducted at 190 ambulatory cardiology care and specialist practices in northern Europe between March 1999 and March 2005 with a median follow-up of 4.8 years, which enrolled 8888 patients aged 80 years or younger with a history of acute MI. INTERVENTIONS: Patients were randomly assigned to receive a high dose of atorvastatin (80 mg/d; n = 4439), or usual-dose simvastatin (20 mg/d; n = 4449). MAIN OUTCOME MEASURE: Occurrence of a major coronary event, defined as coronary death, confirmed nonfatal acute MI, or cardiac arrest with resuscitation. RESULTS: During treatment, mean LDL-C levels were 104 (SE, 0.3) mg/dL in the simvastatin group and 81 (SE, 0.3) mg/dL in the atorvastatin group. A major coronary event occurred in 463 simvastatin patients (10.4%) and in 411 atorvastatin patients (9.3%) (hazard ratio [HR], 0.89; 95% CI, 0.78-1.01; P = .07). Nonfatal acute MI occurred in 321 (7.2%) and 267 (6.0%) in the 2 groups (HR, 0.83; 95% CI, 0.71-0.98; P = .02), but no differences were seen in the 2 other components of the primary end point. Major cardiovascular events occurred in 608 and 533 in the 2 groups, respectively (HR, 0.87; 95% CI, 0.77-0.98; P = .02). Occurrence of any coronary event was reported in 1059 simvastatin and 898 atorvastatin patients (HR, 0.84; 95% CI, 0.76-0.91; P<.001). Noncardiovascular death occurred in 156 (3.5%) and 143 (3.2%) in the 2 groups (HR, 0.92; 95% CI, 0.73-1.15; P = .47). Death from any cause occurred in 374 (8.4%) in the simvastatin group and 366 (8.2%) in the atorvastatin group (HR, 0.98; 95% CI, 0.85-1.13; P = .81). Patients in the atorvastatin group had higher rates of drug discontinuation due to nonserious adverse events; transaminase elevation resulted in 43 (1.0%) vs 5 (0.1%) withdrawals (P<.001). Serious myopathy and rhabdomyolysis were rare in both groups. CONCLUSIONS: In this study of patients with previous MI, intensive lowering of LDL-C did not result in a significant reduction in the primary outcome of major coronary events, but did reduce the risk of other composite secondary end points and nonfatal acute MI. There were no differences in cardiovascular or all-cause mortality. Patients with MI may benefit from intensive lowering of LDL-C without an increase in noncardiovascular mortality or other serious adverse reactions.Trial Registration ClinicalTrials.gov Identifier: NCT00159835.

Aged↗
PubMed2005

Estradiol fatty acid esterification is increased in high density lipoprotein subclass 3 isolated from hypertriglyceridemic subjects.

Estrogen fatty acid esters are potent lipophilic estrogens transported exclusively in lipoproteins. They are formed in HDL in a reaction catalyzed by LCAT which is considered a prerequisite for their antioxidative action. Our previous studies in normotriglyceridemic (NTG) individuals demonstrated that estradiol (E2) esterification occurred mainly in HDL3 causing accumulation of esterified, but not of unesterified E2 in the lipoprotein particles. Using HDL obtained from hypertriglyceridemic (HTG) patients, we now investigated the effect of altered HDL composition on E2 esterification. Ultracentrifugally isolated HDL2 and HDL3 from NTG- and HTG-males were incubated in an in vitro model system with radioactive and with supraphysiological concentrations of non-radioactive E2 with and without exogenous LCAT. After purification, copper-induced oxidation of HDL was measured by monitoring conjugated diene formation. The results demonstrated that (i) E2 esterification occurring mainly in HDL3 was significantly more efficient in HTG-HDL3 compared to NTG-HDL3, (ii) triglyceride content in HDL3 correlated positively with E2 esterification rate, and (iii) addition of both exogenous LCAT and E2 into the incubation prolonged lag time of HDL3 oxidation. Thus, HDL composition regulates LCAT-facilitated E2 esterification but the in vivo role of this finding can be verified only in experiments using physiological hormone concentrations.

Esterification↗
PubMed2005

Estrogen A-ring structure and antioxidative effect on lipoproteins.

The oxidative modification of lipoprotein particles is an important step in atherogenesis. Estrogens are known to be powerful antioxidants independently of their binding to the estrogen receptors and the hormonal functions. We explored the structural determinants for the antioxidant activity of a large number of estrogen derivatives (n=43) in an aqueous lipoprotein solution in vitro by monitoring formation of conjugated dienes. Our results indicate that estrogen derivatives with an unsubstituted A-ring phenolic hydroxyl group with one or two adjacent methoxy groups provide strongest antioxidant protection of low density lipoprotein (LDL) and high density lipoprotein (HDL). The electron donating methoxy groups may enhance the antioxidant effect by weakening the phenolic OH bond and providing stability to the formed phenoxyl radical. With some exceptions, compounds completely lacking unsubstituted hydroxyl groups in the A-ring exhibited no antioxidant effect, e.g. the most hydrophilic "tetrol" compound with three unsubstituted A-ring hydroxyl groups had no antioxidant effect. Moreover, additional hydroxyl groups in the B-, C- or D-ring seemed to weaken the antioxidant effect. Accordingly, both the presence of unsubstituted hydroxyl groups and adjacent substituents, as well as the lipophilicity of the derivatives determine the antioxidant activity of estrogen derivatives in aqueous lipoprotein solutions.

Antioxidants↗
PubMed2004

Design and baseline characteristics of the Incremental Decrease in End Points through Aggressive Lipid Lowering study.

The Incremental Decrease in End Points through Aggressive Lipid Lowering (IDEAL) study is an investigator-initiated trial designed to determine whether additional clinical benefit might be gained through a strategy that decreases levels of low-density lipoprotein cholesterol levels better than those currently achieved with established statin therapy in patients who have coronary heart disease. IDEAL is a multicenter prospective, randomized, open-label, blinded, end point classification study. Patients who had myocardial infarction were randomized to prescription treatment with 80 mg/day of atorvastatin or 20 mg/day of simvastatin (the dose was increased to 40 mg/day at week 24 in those patients whose plasma total cholesterol remained >5.0 mmol/L, or 190 mg/dl, or whose low-density lipoprotein cholesterol remained >3.0 mmol/L, or 115 mg/dl). The primary clinical outcome variable is the time to initial occurrence of a major coronary event, which is defined as nonfatal acute myocardial infarction, coronary death, or resuscitated cardiac arrest. The study is designed to have a power of 90% to detect a relative decrease of 20% in the atorvastatin-group compared with the simvastatin-group in the number of major events caused by coronary heart disease over approximately 5.5 years. The 8,888 randomized patients had the following characteristics: mean age 61.7 +/- 9.5 years, 19.1% women (mean age 64.0 +/- 9.5 years), baseline total cholesterol 5.1 +/- 1.0 mmol/L (197 mg/dl), low-density lipoprotein cholesterol 3.2 +/- 0.9 mmol/L (124 mg/dl), and high-density lipoprotein cholesterol 1.2 +/- 0.3 mmol/L (46 mg/dl). Drug treatment before randomization consisted of statins in 77% of patients, aspirin in 78.9%, beta blockers in 75.1%, and angiotensin-converting enzyme inhibitors in 30%.

Adult↗
PubMed2004

Is there any link between insulin resistance and inflammation in established preeclampsia?

Both insulin resistance and inflammation may contribute to the onset of preeclampsia. They also could be interrelated. We studied the relationship between inflammatory cytokines and markers of insulin resistance. During their third trimester, 22 proteinuric preeclamptic women and 16 normotensive controls underwent intravenous glucose tolerance test (minimal model). Preeclamptic women were more insulin-resistant (P = .009), and they had higher levels of serum soluble tumor necrosis alpha receptor II (TNFalpha RII) (P = .002), triglycerides (P = .006), uric acid (P = .001), and leptin (P = .002) than did the controls. However, the study groups did not differ in serum TNFalpha, C-reactive protein (CRP), interleukin-6 (IL-6), sex hormone-binding globulin (SHBG), and high-density lipoprotein-2 (HDL(2))-cholesterol. In multiple regression analysis only SHBG (P = .01) and triglycerides (P = .0036) were associated with insulin sensitivity independently of body mass index (BMI), weight gain, HDL(2)-cholesterol, CRP, TNFalpha, and TNFalpha RII, IL-6, and leptin. We conclude that insulin resistance and the inflammatory markers studied were not associated in established preeclampsia.

Biomarkers↗
PubMed2004

Effect of 12-month statin therapy on antioxidant potential of LDL and serum antioxidant vitamin concentrations.

BACKGROUND: Statins are known to cause short-term reduction in serum lipid-soluble antioxidant concentrations, but their long-term effects are not known. AIM: We randomised 104 subjects with CHD and hypercholesterolaemia to receive either atorvastatin or simvastatin treatment for 52 weeks and measured the antioxidant potential of LDL and serum antioxidant vitamin concentrations. METHOD: Initial daily dose for both statins was 20 mg. RESULTS: LDL antioxidant capacity and serum alpha-tocopherol, gamma-tocopherol and beta-carotene concentrations decreased by 22%-35% with both statins during the first 12 weeks' therapy (P < 0.01 for all). After 52 weeks' therapy, the concentrations of serum gamma-tocopherol in the simvastatin group and serum beta-carotene in both treatment groups returned to baseline levels, while the concentrations of serum gamma-tocopherol in the atorvastatin group and LDL anti-oxidant capacity and serum alpha-tocopherol in both treatment groups remained reduced (P < 0.001 for all). The LDL antioxidant capacity:LDL-cholesterol and the serum alpha-tocopherol:LDL-cholesterol ratios were significantly elevated with both statins after 12 and 52 weeks (P < 0.001 for all). Statistically significant increases were also observed for corresponding ratios of the less abundant vitamins gamma-tocopherol and beta-carotene. CONCLUSIONS: Some of the decreases in serum lipid soluble antioxidant vitamins reported in short-term statin interventions may become attenuated when therapy continues longer. The relative antioxidant capacity of LDL particles increased during the 52-week treatment, suggesting that the oxidation resistance of LDL particles did not become impaired and that their atherogenicity did not increase.

Atorvastatin↗
PubMed2004

Postmenopausal estrogen therapy and serum estradiol fatty acid esters in women with and without previous intrahepatic cholestasis of pregnancy.

BACKGROUND: Fatty acid esters of 17beta-estradiol (E2) are estrogen metabolites associated with lipoproteins in blood. AIM: To study the effects of estrogen therapy on concentrations of serum E2 fatty acid esters in postmenopausal women with a history of an estrogen-related liver disorder, intrahepatic cholestasis of pregnancy (ICP), and in healthy women in a double-blind, crossover fashion. METHOD: ICP (n = 10) and control women (n = 10) received increasing doses of E2 valerate orally 2-4 mg/day, or transdermal E2 50-100 microg/day for 6 weeks. After a 4-week wash-out period, the subjects crossed over to the alternate E2 treatment. Concentrations of serum E2 fatty acid esters were quantified after saponification by fluoroimmunoassay. RESULTS: Oral E2 administration increased median serum E2 fatty acid ester concentrations from 57 to 73 pmol/L in the ICP and from 56 to 74 pmol/L in the control group, in association with elevations in serum E2, estrone and sex hormone-binding globulin levels. Transdermal E2 treatment did not increase serum E2 ester levels. CONCLUSIONS: The increase in serum E2 fatty acid esters during oral E2 administration may be attributed, at least partly, to the higher estrogen dose during oral compared with transdermal therapy. A history of ICP did not affect esterification of E2 during estrogen therapy.

Case-Control Studies↗
PubMed2004

Lecithin/cholesterol acyltransferase induces estradiol esterification in high-density lipoprotein, increasing its antioxidant potential.

Endogenous estrogens protect against atherosclerosis, but the exact mechanisms remain unclear. One possibility is inhibition of lipoprotein oxidation. To act as antioxidants, estrogens reportedly need to be converted to lipophilic estrogen fatty acyl esters in a reaction catalyzed by lecithin/cholesterol acyltransferase (LCAT). To demonstrate directly that estradiol (E2) esters formed by LCAT and incorporated in high-density lipoprotein (HDL) increase its antioxidant potential, we investigated the copper-induced oxidation of purified HDL after incubations of: 1) HDL alone; 2) HDL in the presence of exogenous E2; 3) HDL in the presence of exogenous LCAT; 4) HDL in the presence of both E2 and LCAT; and 5) HDL in the presence of E2, LCAT, and the LCAT inhibitor DTNB. We used this in vitro model system with supraphysiological concentrations of E2 and purified LCAT to produce E2 ester-containing HDL particles for studies of oxidation resistance. The lag time of HDL oxidation significantly increased with increasing contents of HDL-associated E2 esters. In conclusion, our results clearly demonstrated the role of LCAT in E2 esterification and its involvement in antioxidant protection of HDL. Elucidation of the possible in vivo role of HDL-associated estrogen esters requires further critical studies including experiments with physiological hormone concentrations.

Antioxidants↗
PubMed2003

Accumulation of genistein and lipophilic genistein derivatives in lipoproteins during incubation with human plasma in vitro.

Atherosclerosis is initiated by the uptake and retention of oxidized low-density lipoprotein (LDL) into the arterial intima. We have previously shown that dietary isoflavone phytoestrogens inhibit LDL oxidation in vitro. The inhibition could have been caused by undetected isoflavone metabolites associated with lipoproteins. In the present study, we incubated human plasma with [3H]genistein, both with and without the lecithin:cholesterol acyltransferase (LCAT) inhibitor dithionitrobenzoic acid (DTNB). Our results indicated that the 3H-label was attached to both high-density lipoprotein (HDL) and LDL, and that it represented both underivatized genistein and lipophilic derivatives of genistein, part of which were identified as fatty acid monoesters. The latter was demonstrated by the findings that DTNB decreased the HDL and LDL associated radioactivity in the lipophilic fraction isolated by hydrophobic chromatography and that saponification hydrolysis liberated a corresponding part of the 3H-label. Two-dimensional reversed-phase thin-layer chromatography (TLC) demonstrated that a corresponding part of the radioactivity comigrated with genistein monoester standards in the absence of DTNB but was abolished if DTNB had been present in the incubation. In summary, incubation of plasma with [3H]genistein resulted in accumulation of underivatized genistein as well as lipophilic genistein derivatives in lipoproteins. A smaller part of the latter were genistein monoesters, while part remained unidentified. Our results suggest an explanation for the increased oxidation resistance of isolated LDL during intake of soybean isoflavones.

Dithionitrobenzoic Acid↗
PubMed2003

A 52-week, multicenter, randomized, parallel-group, double-blind, double-dummy study to assess the efficacy of atorvastatin and simvastatin in reaching low-density lipoprotein cholesterol and triglyceride targets: the treat-to-target (3T) study.

BACKGROUND: Guidelines for the prevention of coronary heart disease call for low-density lipoprotein cholesterol (LDL-C) reduction as the primary target of treatment and reduction of triglycerides (TG) as an additional target. OBJECTIVE: The purpose of this study was to investigate the ability of atorvastatin and simvastatin to reduce LDL-C and TG concentrations and to meet 3 target lipid levels: LDL-C or=4.0 mmol/L (>or=155 mg/dL), were randomized in a 1:1 ratio to receive once-daily oral treatment with 20 mg atorvastatin or 20 mg simvastatin. Fasting (12-hour) blood samples for the estimation of lipid levels and clinical laboratory values were collected after 4, 8, 12, 26, and 52 weeks. The dose was doubled after 12 weeks if the target National Cholesterol Education Program level of LDL-C (<or=2.6 mmol/L [100 mg/dL]) was not reached at 8 weeks. RESULTS: The intent-to-treat analysis included 552 patients (418 men, 134 women) randomized to receive atorvastatin and 535 (404 men, 131 women) randomized to receive simvastatin. The number of patients enrolled in the study allowed the evaluation fo the drugs' effects on TG. Patient demogrpahic characteristics were similar for the 2 treatment groups, and there were no differences in baseline lipid values. Compared with simvastatin, atorvastatin produced significantly greater reductions in LDL-C (8 weeks: -46% vs -40%, P < 0.001; 52 weeks: -49% vs -44%, P < 0.001) and in TG (8 weeks: -23% vs -14%, P < 0.001; 52 weeks: -24% vs -16%, P < 0.001). Compared with simvastatin-treated patients, a significantly greater number of atorvastatin-treated patients reached the LDL-C target after 8 weeks (45% vs 24%; P < 0.001). Fewer atorvastatin patients needed to have their dose doubled; nevertheless more atorvastatin patients reached the LDL-C target after 52 weeks (61% vs 41%; P < 0.001). Both statins were well tolerated. Muscular symptoms occurred in 12 patients (2.2%) in the atorvastatin group and in 13 patients (2.4%) in the simvastatin group. CONCLUSIONS: Atorvastatin 20 or 40 mg/d for up to 1 year of treatment was significantly more effective than simvastatin 20 or 40 mg/d in reducing LDL-C and TG levels and at achieving recommended lipid targets in this selected patient population with cardiovascular disease and dyslipidemia. Both statis were well tolerated.

Adult↗
PubMed2003

Differential effects of oral and transdermal estradiol treatment on circulating estradiol fatty acid ester concentrations in postmenopausal women.

Estradiol fatty acid esters are potent lipophilic estrogens with antioxidant properties, transported by lipoproteins in blood. We investigated effects of oral and transdermal estradiol replacement therapy on concentrations of estradiol fatty acid esters in serum in postmenopausal women in a double-blind, randomized fashion. The first group (n = 9) received oral (2 mg/d); the second (n = 10), transdermal estradiol (patch delivering 50 microg/d); and the third group (n = 7), placebo treatment for 12 wk. After extraction of serum and separation of esterified estradiol from nonesterified estradiol, the concentration of saponified estradiol esters was measured by time-resolved fluoroimmunoassay. In the oral estradiol group, the median serum estradiol fatty acid ester concentration rose by 27%, from 77 to 98 pM (P = 0.028) but remained unchanged in the transdermal estradiol and placebo groups. The median concentrations of serum nonprotein-bound estradiol increased similarly in the oral and transdermal estradiol groups. The change in serum estradiol ester concentrations during treatment, but not that of nonesterified estradiol, correlated positively with enhanced forearm blood flow responses in vivo. These data raise the possibility that an increase in serum estradiol fatty acid esters may contribute to beneficial effects of oral estradiol treatment, compared with an equipotent dose of transdermal estradiol.

Administration, Cutaneous↗
PubMed2003

Quantitative determination of estradiol fatty acid esters in lipoprotein fractions in human blood.

According to experimental studies, 17 beta-estradiol associates with lipoproteins in blood in the form of fatty acid esters. However, concentrations of endogenous estradiol esters in human lipoprotein fractions have not been previously reported. We investigated the distribution of estradiol fatty acid esters between plasma lipoproteins in 10 healthy women during late pregnancy. Following extraction from serum and ultracentrifugally isolated, gel-filtered lipoproteins, estradiol esters were separated from nonesterified estradiol by column chromatography. After saponification and chromatographic purification of the estradiol ester fraction, the concentration of hydrolyzed esters was determined by estradiol time-resolved fluoroimmunoassay. Of total serum estradiol, a mean of 0.7% (549 pmol/liter, n = 10) was in the form of fatty acid esters. Estradiol fatty acid ester concentrations measured in serum and lipoprotein fraction correlated positively (n = 10; r = 0.98; P < 0.001). The majority of lipoprotein estradiol esters, 54%, was recovered in high-density lipoprotein, and 28% in low-density lipoprotein fraction. Most lipoprotein fractions contained undetectable amounts of nonesterified estradiol (< 36 pmol/liter). In conclusion, our results indicate that estradiol fatty acid esters are mostly bound by lipoproteins in blood in vivo.

Adult↗
PubMed2002

Lipoprotein-associated estrogens.

The discovery of a family of hormonal steroids esterified with fatty acid has raised questions concerning their physiologic role. Because of their water-insolubility these compounds are present in the circulation only as components of lipoprotein particles. Current evidence supports the hypothesis that estrogen esterification is catalyzed by lecithin:cholesterol acyltransfearse associated with HDL. In addition, recent results indicate that estradiol esters are transferred from HDL to LDL particles in a cholesteryl ester transfer protein (CETP)-associated process. The studies now focus on the various possible physiologic roles proposed for these hormone derivatives, (1) functioning as fat-soluble antioxidants incorporated in lipoproteins rendering protection against oxidation of these particles, (2) providing a mechanism for hormonal storage in lipoproteins and fat tissues, (3) providing a novel hormone transport system using lipoprotein as carriers and lipoprotein receptors for entry into cells. Quantitative methods of determination of estradiol fatty acid esters in human body fluids have been developed. Preliminary studies suggest that diet-derived plant estrogens may also form fat-soluble derivatives which become incorporated in lipoproteins.

Antioxidants↗