Biomedical subjects

Tord Naessen

Publications and source records attributed to Tord Naessen.

9 recordsLinked to original sources

PubMed2006

Thicker carotid intima layer and thinner media layer in subjects with cardiovascular diseases. An investigation using noninvasive high-frequency ultrasound.

BACKGROUND: The thickness of the arterial intima increases and that of the media decreases with increasing age and degree of atherosclerosis. Separate estimates of the individual intima and media layers might therefore be more appropriate than the commonly used method estimating the combined intima-media thickness (IMT). METHODS AND RESULTS: One hundred consecutive 70-year-old subjects from the PIVUS study were investigated. Separate estimates of the thickness of the carotid artery intima and media wall layers were carried out noninvasively using 25MHz high-frequency ultrasound. Subjects with a diagnosis of cardiovascular disease (CVD), coronary heart disease (CHD), myocardial infarction (MI) or stroke had a significantly thicker intima layer (all P<0.0001) and a thinner media layer (all P<0.05) than healthy subjects. The intima/media thickness ratio also differed significantly between subjects with and without a diagnosis of CVD (0.43+/-0.20versus 0.75+/-0.48, P=0.0002). Subjects with hypertension or hyperlipidemia also had a thicker carotid intima than subjects without these diagnoses (P<0.0005 for both). None of the corresponding intima+media thickness values differed significantly. Similar results were obtained in women and men. CONCLUSION: Separate assessment of carotid artery intima and media thickness using noninvasive high-frequency ultrasound appears to be of potential value, as a striking difference in intima thickness and the intima/media thickness ratio was found between subjects with and without CVD.

Aged↗

PubMed2006

Menopausal estrogen therapy counteracts normal aging effects on intima thickness, media thickness and intima/media ratio in carotid and femoral arteries. An investigation using noninvasive high-frequency ultrasound.

BACKGROUND: Estrogen therapy that is started at the time of menopause seems to protect against the development of atherosclerosis and cardiovascular diseases, in contrast to the initial increased cardiovascular risk when hormone therapy is initiated in older women. With increased aging and degree of atherosclerosis, the thickness of the artery intima increases and that of the media decreases. These changes can be noninvasively estimated using high-frequency ultrasound. METHODS AND RESULTS: The thickness of carotid and femoral artery intima and media was assessed, using noninvasive high-frequency ultrasound (25MHz). Long-term estrogen users (mean treatment duration 20 years) had a significantly thinner mean carotid intima layer (-25%; P=0.0002), a thicker media layer (+74%; P=0.0002) and a substantially lower intima/media thickness ratio (-54%; P<0.0001) than 17 age-matched nonusers, with values closer to those in 20 premenopausal women. Similar but less pronounced differences between the postmenopausal groups were found for the femoral artery. CONCLUSIONS: A preserved thin artery wall intima and a low intima/media thickness ratio, at values close to those in young women might be partially responsible for the beneficial cardiovascular effects of estrogen therapy when it is initiated at the time of menopause.

Adult↗

PubMed2006

Granulosa cell aromatase enzyme activity: effects of follicular fluid from patients with polycystic ovary syndrome, using aromatase conversion and [11C]vorozole-binding assays.

The local regulation of ovarian aromatase enzyme in polycystic ovary syndrome (PCOS) was studied with aromatase conversion and [11C]vorozole-binding assays to analyze aromatase activity, substrate-enzyme affinity and number of aromatase binding sites in non-cultured human granulosa cells (GC) incubated with different sources and preparations of follicular fluid (FF). Incubation with FF from women stimulated in in vitro fertilization cycles with follicle-stimulating hormone yielded higher conversion activity than with FF from healthy women and PCOS patients, paralleled with higher substrate affinity (lower Kd) than with FF from healthy women. In PCOS women, charcoal-pretreated FF yielded higher conversion, whereas the ether-pretreated FF yielded lower conversion activity, than with untreated PCOS FF. Both preparations of FF yielded higher affinity to substrate (lower Kd values) and the ether-pretreated FF a lower number of binding sites (Bmax). It seems that steroids with the presence of proteins in PCOS FF reduced aromatase conversion activity through decreased substrate affinity, whereas FF preparations devoid of proteins reduced the aromatase conversion activity mainly through blocking of aromatase active sites. Identification of specific agents responsible for this rapid regulation of aromatase function might help to understand normal regulation of the menstrual cycle and supposed imbalances of inhibitors/activators in PCOS.

Aromatase↗

PubMed2006

Risk factors associated with snoring in women with special emphasis on body mass index: a population-based study.

STUDY OBJECTIVES: Habitual snoring may be regarded as an indicator of sleep-disordered breathing, and the health consequences of sleep-disordered breathing are well-known. The aim of this study was to analyze the risk factors associated with habitual snoring in a large sample of women, with special emphasis on the determinants of snoring in women with different body mass index (BMI) levels. DESIGN AND SETTING: A cross-sectional, epidemiologic, population-based study was performed by using a postal questionnaire that was sent to a randomly selected sample of 6,817 women >/= 20 years of age in Uppsala, Sweden. RESULTS: The total prevalence of self-reported habitual snoring was 7.6%. There was a clear age dependence, with the highest prevalence of habitual snoring (14%) occurring between the ages of 50 and 59 years. Self-reported habitual snoring was related to BMI, neck circumference, and smoking >/= 10 cigarettes a day, after adjusting for possible confounders. When analyzing the influence of different risk factors in separate BMI groups, the results varied among the groups. The influence of alcohol dependence on snoring frequency was only significant in women with a BMI of < 20 kg/m(2), while physical inactivity was only associated with habitual snoring in women with a BMI of >/= 30 kg/m(2). CONCLUSIONS: The prevalence of self-reported habitual snoring in women was strongly dependent on age and BMI. The importance of other risk factors differed depending on BMI, with alcohol dependence being associated with self-reported snoring in lean women, whereas physical inactivity was a risk factor for self-reported snoring in women with a high BMI.

Adult↗

PubMed2003

Characterization of [11C]vorozole binding in ovarian tissue in rats throughout estrous cycle in association with conversion of androgens to estrogens in vivo and in vitro.

Estrogen levels vary in a cyclic fashion during the rat estrous cycle, reaching peak concentrations during proestrus. Previously, it was suggested that the preovulatory peak in estrogen production in rats in vivo is regulated by other control mechanisms than concentration of precursor and amount of aromatase enzyme, changing the specific activity of the enzyme. To explore this hypothesis, ovarian binding of [11C]vorozole in vivo and in vitro, representing the amount of active aromatase, and conversion activity of ovarian homogenate were assayed together with serum androstenedione (A4) and estradiol-17beta (E2) levels during the estrous cycle in rats. The reducing ovarian [11C]vorozole binding in vivo from proestrus +4 up to +8h might indicate that the ovarian aromatase is blocked, probably to prevent premature increase of E2 levels. Thereafter (between proestrus +9 and +13h), the binding dramatically increases (aromatase enzyme is unblocked), to enable increased E2 synthesis. In addition, during the latter period, serum E2 levels were strongly correlated with serum A4 levels after adjustment for amount of ovarian aromatase (P=0.03), but not with amount of aromatase adjusted for levels of A4 (P=0.13), which might indicate changes in specific activity of the aromatase enzyme. Significant correlation between Kd and serum E2 levels during the same period indicated that aromatase-precursor affinity might be involved in the regulation of the enzyme-specific activity. This conclusion is done assuming that [11C]vorozole binding mimics that of the substrate (A4). The [11C]vorozole in vivo technique keeps auto- and paracrine mechanisms intact, and might therefore yield additional information about biological processes compared with traditional in vitro techniques.

Androstenedione↗

PubMed2003

Effects of androgens on aromatase activity and 11C-vorozole binding in granulosa cells in vitro.

BACKGROUND: Locally produced androgens and estrogens are important in the hormonal regulation of follicular development. The present study aimed to further elucidate the mechanism through which androgens exert their ambivalent effects on aromatization. METHODS: Non-cultured human granulosa-luteal cells (GC) were treated with different concentrations of androstenedione (A4), testosterone (T), 5alpha-androstane-3,17-dione (5alpha-A) and dihydrotestosterone (DHT). The effects on aromatase activity were evaluated in a tritiated water assay (incubation time 2 h) and the availability of aromatase active sites was measured in a radiotracer-binding assay using the non-steroidal competitive aromatase inhibitor [11C]-vorozole (incubation time 15 min). RESULTS: A4, T and 5alpha-A caused dose-dependent inhibition of both aromatase activity and [11C]-vorozole binding; IC50-values for both inhibition processes were calculated for these three steroids, revealing A4 as the most potent inhibitor and T and 5alpha-A as moderate inhibitors. At low concentrations (0.01 and 0.1 micro M), DHT stimulated aromatase activity but did not affect [11C]-vorozole binding. At the higher concentrations tested (1 and 10 micro M) DHT suppressed both processes thus weakly binding the aromatase active site. CONCLUSION: Because the incubation time in the tritiated water assay was short, the stimulation by DHT at low concentrations might therefore most likely include mechanisms other than new synthesis of aromatase protein such as allosteric action of DHT upon aromatase or liganded androgen receptor-aromatase interaction.

Androgens↗

PubMed2002

Arterial stiffness is not improved in long-term use of estrogen.

OBJECTIVE: The purpose of this study was to compare arterial stiffness in long-term users of estrogen who were postmenopausal, age-matched women who did not use estrogen, and women of fertile age. STUDY DESIGN: In this clinical cross-sectional study, carotid, femoral, and aortic stiffness (estimated as elastic modulus and stiffness beta index) were assessed by ultrasonic phase-locked echo-tracking in 17 women who were postmenopausal and who were treated with 17 beta-estradiol implants (mean age, 68.8 years; mean duration of treatment, 20 years), 17 age-matched (+/-1 year) untreated women, and 20 women in the fertile age period. RESULTS: Compared with women of fertile age, both postmenopausal groups had significantly higher stiffness elastic modulus and stiffness beta index (carotid, P <.001; femoral, P <.05; aorta, P <.001). However, for all 3 arteries, both stiffness indices were similar in estrogen users and nonusers and did not differ significantly. These results remained after an adjustment for systolic blood pressure, body mass index, and low-density lipoprotein cholesterol levels. CONCLUSION: These data indicate that the arterial stiffening that is related to aging/menopause is not substantially affected by long-term estrogen therapy.

Adult↗

PubMed2002

Endometrial thickness and uterine diameter not affected by ultralow doses of 17beta-estradiol in elderly women.

OBJECTIVE: Our purpose was to monitor changes in endometrial thickness and uterine diameter during treatment with ultralow doses of estradiol, which might improve the serum lipid profile in elderly women. STUDY DESIGN: Ultrasonographic changes were monitored in 60 women with an intact uterus in a group of 70 healthy women who were previously evaluated for changes in serum lipid levels. Subjects were 60 years and older and were randomly assigned to receive parenteral 17beta-estradiol (7.5 microg/24 h), delivered by a vaginal ring (Estring; Pharmacia-Upjohn, Malmö, Sweden), or no treatment for 12 months. RESULTS: Estring treatment yielded minor increases in serum estrone sulfate and 17beta-estradiol levels within the normal postmenopausal range. The maximal endometrial thickness was 2.8 mm at baseline and 2.6 mm at 12 months. No significant changes within or between the study groups were found in endometrial thickness or uterine diameter. There were no significant interactions between age and baseline serum estrone sulfate or 17beta-estradiol levels. CONCLUSIONS: Ultralow doses of 17beta-estradiol, which might improve serum lipid levels, did not significantly change endometrial thickness or uterine diameter. This might indicate that there is a "therapeutic window" for systemic effects of ultralow doses of estradiol in elderly women without any apparent increase in endometrial thickness.

Aged↗

PubMedDate not supplied

Early postmenopausal hormone therapy improves postural balance.

OBJECTIVE: Postmenopausal hormone therapy (HT) results in more substantial reductions in the risk of hip fracture when initiated sooner rather than later after menopause. We studied the effects of postmenopausal HT on the postural balance of postmenopausal women, with further assessment according to the time since they achieved menopause. DESIGN: One hundred women with a mean age of 52.5 years (91 evaluable) were randomly and blindly assigned to either a sequential estradiol-norethisterone acetate regimen or placebo for 3 months, after which all participants received open HT for a further 3 months. Postural balance was assessed as sway velocity using a force platform. RESULTS: After 3 months of HT, sway velocity had improved (decreased) from baseline by 7.0% (P = 0.007 vs baseline and P = 0.038 vs placebo). Continued HT for 6 months further improved sway velocity by 12% from baseline (P < 0.0001) to reach values similar to those historically found in younger women or in postmenopausal women after long-term HT. Closer proximity to menopause and more pronounced increases in serum estradiol values were associated with stronger improvements in sway velocity (P = 0.018 for interaction). HT also improved dizziness (P = 0.016 vs baseline and 0.022 vs placebo). (Nonparametric statistics are used throughout, except for analyses of interaction and dizziness.) CONCLUSIONS: Initiation of HT soon after menopause rapidly improved postural balance to levels normally seen in young women. We suggest that improved postural balance can contribute to the protection against fractures associated with HT and explain the more substantial reduction in hip fracture risk after HT initiated sooner, compared with later, after menopause. Further study is required to confirm these results.

Dizziness↗