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Biomedical subjects

Tomi S Mikkola

Publications and source records attributed to Tomi S Mikkola.

15 recordsLinked to original sources
PubMed2006

Mifepristone-induced nitric oxide release and expression of nitric oxide synthases in the human cervix during early pregnancy.

BACKGROUND: Nitric oxide (NO) is a factor in cervical ripening, perhaps under the control of progesterone. We studied the effects of the antiprogesterone mifepristone on the release of NO and on the expression of inducible NO synthase (iNOS) and endothelial NO synthase (eNOS) in the uterine cervix of women in early pregnancy. METHODS: Thirteen women were treated with oral mifepristone (200 mg), and 15 women were studied as controls. Cervical fluid samples were collected before treatment then hourly up to 3 h, and the samples were assayed for the concentration of nitric oxide metabolites (NOx). In addition, cervical biopsy samples from six women treated with mifepristone and from six controls were assessed for iNOS and eNOS by immunohistochemistry and Western blotting. RESULTS: In 1-3 h, mifepristone induced 7.4- to 17.2-fold elevations in cervical fluid NOx concentrations; no change was seen in the controls. The expression of both iNOS and eNOS was detected in the cervical cells. The expression of cervical iNOS was strong in five of the six women treated with mifepristone but was not strong in any of the six control women. CONCLUSION: This is the first study to show that mifepristone stimulates the release of NO and the expression of iNOS in cervical cells of women in early pregnancy. This may be one mechanism by which mifepristone initiates cervical ripening.

Abortion, Induced↗
PubMed2005

Vasoactive intestinal peptide--release from the heart and response in heart failure due to left ventricular pressure overload.

BACKGROUND: Vasoactive intestinal peptide (VIP) is a peptidergic neurotransmitter and a vasodilator with positive inotropic and chronotropic properties. Whether and how VIP contributes to the neuroendocrine response in heart failure (HF) is disputed, and there are no data on VIP in pressure overload-induced HF. METHODS: We studied 129 adults with isolated aortic valve stenosis (AS). Blood was sampled from the aortic root and, in a subset of 48 patients, also from the coronary sinus for determination of VIP by radioimmunoassay. HF was diagnosed according to the European Society of Cardiology criteria. RESULTS: Plasma VIP (mean+/-S.E.M.) was slightly higher in patients with HF (22.6+/-0.9 pmol/l, n=41) than in patients free of HF (21.1+/-0.5 pmol/l, n=88) or in 11 control patients without structural heart disease (20.0+/-1.3 pmol/l, n=11) (p=0.030 across the groups). VIP did not correlate with any measurement of cardiac structure or function in AS. The change in plasma VIP from aortic root to coronary sinus averaged +1.2+/-0.4 pmol/l in the 11 control patients (p=0.021), +1.2+/-0.2 pmol/l in 33 AS patients free of HF (p<0.001) and +0.8+/-0.3 pmol/l in 15 AS patients with HF (p=0.037). CONCLUSIONS: Both structurally normal and diseased hearts release VIP into the coronary sinus. Although marginally elevated in the systemic circulation, VIP is unlikely to contribute significantly to the neuroendocrine activation in HF due to pressure overload.

Adult↗
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

Is the pregnancy hormone relaxin an important player in human heart failure?

BACKGROUND: The pregnancy hormone relaxin has been raised as a new compensatory mediator of cardiac origin in heart failure (HF). We set out to assess the role of relaxin in pressure overload-induced human HF. METHODS: We studied 129 adult patients undergoing cardiac catheterization for isolated aortic valve stenosis (AS). Blood was sampled from the aortic root and, in a subset of 49 patients, from the coronary sinus for the determination of plasma relaxin by enzyme immunoassay. HF was diagnosed when the patient had dyspnea or fatigue on ordinary effort in association with pulmonary wedge pressure >14 mm Hg at catheterization. RESULTS: Forty-one patients had HF, which was systolic (ejection fraction <50%) in 16 patients and diastolic in 25 patients. The median plasma relaxin was 32 pg/ml (<12-297 pg/ml) in 88 AS patients without HF, 28 pg/ml (<12-825 pg/ml) in the 41 AS patients with HF, and 42 pg/ml (range, <12-100 pg/ml) in 11 control patients free of heart disease (p=0.82). Plasma relaxin did not correlate with any measurement of cardiac structure or function. The concentration gradients of relaxin from the aortic root to the coronary sinus indicated relaxin extraction by the heart in the control patients (median change, -5 pg/ml, p=0.038) vs. relaxin production in patients with systolic HF (median change, +6 pg/ml, p=0.028) (p=0.002 between groups). CONCLUSIONS: Although the heart may release relaxin into the circulation in certain forms of HF, this does not translate into elevated systemic concentrations. Relaxin is not a major player in human HF.

Adult↗
PubMed2005

Misoprostol induces cervical nitric oxide release in pregnant, but not in nonpregnant, women.

OBJECTIVE: The cells of the human uterine cervix synthesize nitric oxide, which may be a factor in cervical ripening. We studied the effect of misoprostol on cervical nitric oxide release in nonpregnant and pregnant women. STUDY DESIGN: Seventy-two nonpregnant (n=15) and pregnant (n=57; 26 in early pregnancy, 31 in late pregnancy) women were treated with either vaginal misoprostol (n=54) or vaginal placebo (n=18). The dose of misoprostol was 400 mug in nonpregnant and early pregnancy group, and 25 mug in late pregnancy group. Serial cervical fluid samples, collected before and up to 3 hours after misoprostol/placebo, were assessed for the concentration of nitric oxide metabolites by means of the Griess reaction. RESULTS: Placebo had no effect on cervical fluid nitric oxide metabolite level. In 1 to 3 hours, misoprostol induced 4.3- to 5.2-fold elevations in cervical fluid Nox concentrations in early pregnancy (P < .01), and 4.4- to 18.2-fold elevations in late pregnancy (P < .01), but these responses did not differ significantly from each other. Misoprostol had no effect on cervical fluid nitric oxide metabolites in nonpregnant women. There was a trend towards a relationship between cervical nitric oxide stimulation after misoprostol and cervical ripening. CONCLUSION: Vaginal misoprostol stimulates cervical nitric oxide release in pregnancy. This suggests a joint action of nitric oxide and prostaglandins in cervical ripening.

Administration, Intravaginal↗
PubMed2004

Postmenopausal hormone therapy before and after the women's health initiative study: what consequences?

This review focuses on the question of whether the Women's Health Initiative (WHI) was a test of primary versus secondary cardiovascular benefits of postmenopausal hormone therapy. Evidence is presented to support the conclusion that the WHI was a secondary intervention trial and that primary cardiovascular benefits of hormone therapy are rational, likely, but not yet proven. The review makes clear that hormone therapy is not a 'cardiovascular drug' for the treatment of coronary heart disease; but rather that the public health debate is whether hormone therapy, used for the treatment of menopausal symptoms, provides any cardiovascular benefits that might offset its risk.

Age Factors↗
PubMed2004

Increased release of cervical nitric oxide in spontaneous abortion before clinical symptoms: a possible mechanism for preabortal cervical ripening.

Nitric oxide (NO) affects cervical ripening. We studied cervical NO release in women with nonviable pregnancy before signs of abortion. Women with missed abortion (n = 56), blighted ovum (n = 36), or tubal pregnancy (n = 7) were selected by means of vaginal ultrasonographic examination from a population seeking early pregnancy termination; 140 women with amenorrhea-matched normal gestation were studied as controls. Cervical fluid samples were assessed for NO metabolites (Nox) by means of Griess reaction. Cervical fluid Nox was more often detectable in women with missed abortion (90%) and blighted ovum (87%) than in the control women (55%; P = 0.01), and Nox levels in women with missed abortion [median, 59.4 mumol/liter; 95% confidence interval (CI), 30.3-81.8] and blighted ovum (25.6 mumol/liter; 95% CI, 14.1-53.0) were 14 and 6 times higher (P < 0.001 and P = 0.002, respectively) than in the control group (4.3 mumol/liter; 95% CI, <3.8 to 6.4). Nox levels in women with tubal pregnancy were normal. In women with nonviable pregnancy, the lower the level of progesterone, expressed as a percentage of that in the control women, the higher (r = -0.69; P < 0.001) the level of cervical fluid Nox, and those with low pretreatment Nox levels failed to abort completely after mifepristone-misoprostol or expectant management more often (P = 0.04) than women with high Nox levels (28% vs. 4%); no such relationship was seen in the control group. Increased preabortal cervical NO release may contribute to cervical ripening and the onset of clinical abortion.

Abortion, Spontaneous↗
PubMed2003

Serum cholesterol efflux potential is an independent predictor of coronary artery atherosclerosis.

The efflux of cholesterol from cells and its incorporation into HDL is believed to be the initial step in reverse cholesterol transport. This report addresses the question of whether there is a relationship between the ability of serum to promote efflux of cholesterol from cells in culture and the severity of coronary artery atherosclerosis (CAA). Surgically postmenopausal cynomolgus monkeys (n=142) were treated for 2-years with conjugated equine estrogens (CEE), CEE plus medroxyprogesterone acetate, or two different doses of tibolone, a synthetic steroid. CAA was determined at necropsy, and the cholesterol efflux potential of serum from each animal was determined using 3H-cholesterol-labeled Fu5AH cells and human skin fibroblasts in culture. A significant negative correlation was seen between CAA and cholesterol efflux from Fu5AH cells (r=-0.44, P< or =0.0001), but not skin fibroblasts. Although there was a wide range of plasma HDL cholesterol concentrations in these animals (10-81 mg/dl), using multiple regression analysis, LDL+VLDL cholesterol and the serum cholesterol efflux potential were the only significant independent predictors of CAA, explaining 41.6 and 10.7% of the variability (P<0.0001), respectively. Thus, the potential of serum to promote cholesterol efflux from Fu5AH cells may represent a useful independent measure for improving the assessment of CAA risk.

Animals↗
PubMed2002

Estradiol reduces basal and cytokine induced monocyte adhesion to endothelial cells.

OBJECTIVE: To investigate the effect of 17beta-estradiol (E2) on binding of monocytes to human aortic endothelial cells (HAECs) with or without cytokine induction. METHODS: Confluent monolayers of HAECs were incubated with or without E2 for 48 h prior to the monocyte adhesion assay. In studies with cytokines, 1 ng/ml tumor necrosis factor-alpha (TNF-alpha), 20 U/ml interleukin-1beta (IL-1beta) or both were added to the culture medium for the final 24 or 4 h. For the measurement of monocyte adhesion, 3H-thymidine labeled human THP-1 monocytes (4 x 10(5) cells per well) were added to the confluent monolayer of HAECs and incubated at 37 degrees C for 90 min. The unbound THP-1 cells were removed by gentle washing, and bound cells were digested with NaOH and quantified by measuring radioactivity. RESULTS: When HAECs were pretreated for 48 h with E2 the basal adhesion of THP-1 cells was reduced by an average of 28%. Estrogen significantly reduced cytokine-induced adhesion by 30-35% when the cytokines were added for 4 h. When the cytokine treatment was prolonged to 24 h, pretreatment of HAECs with E2 had no effect on THP-1 cell adhesion. CONCLUSIONS: E2 reduces basal and short-term cytokine induced monocyte binding to HAECs. Since monocyte adhesion to vascular endothelial cells is one of the initial steps in the pathogenesis of atherosclerosis, E2 may mediate vascular protection by reducing monocyte-endothelial cell binding in the early stages of atherogenesis.

Cell Adhesion↗
PubMed2002

Estrogen replacement therapy, atherosclerosis, and vascular function.

There is strong evidence from both human and nonhuman primate studies supporting the conclusion that estrogen deficiency increases the progression of atherosclerosis. More controversial is the conclusion that postmenopausal estrogen replacement inhibits the progression of atherosclerosis. Estrogen treatment of older women (>65 years) with pre-existing coronary artery atherosclerosis had no beneficial effects. In contrast, estrogen treatment of younger postmenopausal women or monkeys in the early stages of atherosclerosis progression has marked beneficial effects. Whether progestogens attenuate the cardiovascular benefits of estrogen replacement therapy has been controversial for more than a decade. Current evidence from studies of both monkeys and women suggest little or no attenuation of estrogen benefits for coronary artery atherosclerosis. Lack of compliance with estrogen replacement therapy, usually because of fear of breast cancer, remains a major problem. Future regimens may overcome that fear by the co-administration of a breast cancer preventive agent (i.e., selective estrogen receptor modulators, phytoestrogens) with low dose estrogen.

Aged↗
PubMed2002

Serum cholesterol efflux potential in postmenopausal monkeys treated with tibolone or conjugated estrogens.

Tibolone is a synthetic steroid used for the treatment of climacteric symptoms and the prevention of osteoporosis, but the effect on the cardiovascular system is unclear since tibolone lowers high-density lipoprotein (HDL) levels. We investigated if long-term treatment with tibolone or conventional hormone replacement therapy (HRT) in cynomolgus monkeys could affect their serum cholesterol efflux potential. Surgically postmenopausal cynomolgus monkeys were treated for 2 years with conjugated equine estrogens (CEE), CEE plus medroxyprogesterone acetate (MPA), low-dose tibolone, or high-dose tibolone. Plasma lipid, lipoprotein, and apolipoprotein levels were monitored during the study. The cholesterol efflux potential of the serum from each animal was determined in (3)H-cholesterol-labeled Fu5AH cells and skin fibroblasts in culture. Tibolone induced a dose-dependent 30% to 52% reduction in HDL levels. When HDL concentrations were reduced by 30%, as seen in women, there was no reduction in the serum cholesterol efflux potential in Fu5AH cells. With a 52% reduction in HDL, there was a 14% reduction in cholesterol efflux. Although CEE or CEE+MPA had no significant effect on HDL levels, CEE treatment increased serum cholesterol efflux potential by 7%. With the same sera, no changes in cholesterol efflux were seen with fibroblasts. Although our findings suggest that HDL concentration is correlated with cholesterol efflux potential of serum, this relationship is weak, explaining only 16% of the variability. This is emphasized by the fact that despite a 30% lowering of HDL with tibolone, there was no indication of an adverse effect on cellular cholesterol efflux. Other changes in the serum not measured in this study must contribute significantly to the cholesterol efflux potential of serum. Because changes in cholesterol efflux potential of serum were seen only in Fu5AH cells, a cell line rich in SR-B1 receptors, this implies that the changes seen in this study were mediated largely by the SR-B1 pathway.

Analysis of Variance↗
PubMed2002

Comparison of tibolone and conjugated equine estrogens effects on carotid artery atherosclerosis of postmenopausal monkeys.

BACKGROUND AND PURPOSE: Tibolone is a tissue-specific compound that has favorable effects on bone and menopausal symptoms without stimulating endometrium or breast, but lowers concentrations of plasma high-density lipoprotein (HDL) cholesterol (HDLC). This study was designed to determine whether the HDL lowering with tibolone exacerbated common or internal carotid artery atherosclerosis and to evaluate tibolone treatment relative to conjugated equine estrogens (CEE) alone or in combination with medroxyprogesterone acetate (MPA). METHODS: Carotid artery atherosclerosis was compared in groups of surgically postmenopausal cynomolgus monkeys treated with CEE, CEE+MPA, or either of 2 doses of tibolone versus untreated monkeys. RESULTS: Despite a 30% to 52% lowering of HDLC with tibolone, there was no significant effect on carotid artery atherosclerosis. CEE and CEE+MPA, however, inhibited carotid artery atherosclerosis by approximately 60%. CONCLUSIONS: In surgically postmenopausal cynomolgus monkeys, CEE and CEE+MPA inhibited common and internal carotid artery atherosclerosis. Despite the potentially adverse effects of tibolone on HDLC, tibolone did not exacerbate atherosclerosis.

Animals↗
PubMedDate not supplied

Serum cholesterol efflux potential in postmenopausal women treated with isolated isoflavones.

OBJECTIVE: Based on the low cardiovascular risk in Asian populations, phytoestrogens are believed to provide vascular benefits. To elucidate the mechanisms behind the possible cardiovascular effects of phytoestrogens, we evaluated reverse cholesterol transport by assessing the capacity of serum to promote cholesterol efflux in postmenopausal women treated with isolated isoflavones. DESIGN: Thirty postmenopausal women were treated in a randomized, placebo-controlled, crossover trial with isoflavones or placebo for 3 months interrupted by a 2-month washout period. Serum samples were collected before and after each treatment period, and the cholesterol efflux potential was investigated by using H-cholesterol--labeled Fu5AH cells in culture. RESULTS: Serum promoted 20.2% +/- 3.0% and 19.9% +/- 3.4% (mean +/- SD) cholesterol efflux after isoflavonoid treatment and after placebo treatment, respectively. Thus, the isoflavone treatment did not affect serum cholesterol efflux. We also studied separately women who produced high concentrations of the isoflavone metabolite equol into serum because some studies suggest that equol could exert favorable vascular effects. However, there was no difference in serum cholesterol efflux capacity between the equol producers (n = 15) and non-equol producers (n = 15). CONCLUSIONS: In conclusion, isoflavone treatment did not affect serum cholesterol efflux potential in postmenopausal women. Based on our findings, isolated isoflavones do not provide vascular benefits by improving cholesterol efflux.

Adult↗
PubMedDate not supplied

Effect of isolated isoflavone supplementation on ABCA1-dependent cholesterol efflux potential in postmenopausal women.

OBJECTIVE: Isoflavones may display beneficial health effects in postmenopausal women. We studied in a clinical trial whether isolated isoflavone treatment in postmenopausal women could affect reverse cholesterol transport as evaluated by adenosine triphosphate-binding cassette A1- (ABCA1), dependent cholesterol efflux from macrophages. In addition, various serum lipid and lipoprotein parameters were investigated. Furthermore, we separately assessed equol-producing and non-equol-producing women. DESIGN: Postmenopausal women (n=56) were treated with either isoflavone or placebo tablets for 3 months in a crossover design, separated by a 2-month washout period. Fifteen women were classified as equol producers, and 15 women were classified as non-equol producers. Serum samples were collected before and after each treatment period. [H]-Cholesterol-labeled J774 macrophage cells, with and without ABCA1 up-regulation, were incubated with the samples, and ABCA1-dependent cholesterol efflux and serum lipid and lipoprotein levels were assessed. RESULTS: Serum promoted 3.1%+/-1.1% and 3.2%+/-1.1% cholesterol efflux from macrophages after isoflavone and placebo treatment, respectively. Thus, isoflavone supplementation did not affect ABCA1-dependent cholesterol efflux to serum. However, as a novel finding, isoflavone treatment increased a subclass of high-density lipoprotein, the pre-beta high-density lipoprotein levels by 18% without affecting any other serum lipid concentrations. ABCA1-facilitated cholesterol efflux and lipid parameters did not differ between equol-producing and non-equol-producing women. CONCLUSION: In postmenopausal women, isolated isoflavone treatment does not affect ABCA1-dependent cholesterol efflux potential from macrophages but increases circulating pre-beta high-density lipoprotein level, which could provide beneficial vascular effects.

ATP-Binding Cassette Transporters↗