Work-related well-being of Finnish anesthesiologists

Anesthesiologists, according to some studies, are highly stressed, die at a significantly earlier age than their colleagues and the general population,and are among the leaders in physicians' suicide records. Data are,however, sparse and contradictory. The aim of this study was to discover details of the work-related well-being of Finnish anesthesiologists. In 2004, a cross-sectional postal survey including all 550 working Finnish anesthesiologists produced a total of 328 responses (60%); 53% were men. The anesthesiologists had the greatest on-call workload among Finnish physicians. Their average in-hospital on-call period lasted 24 hours (range 14 to 38). Over two-thirds felt stressed. The most important causes of stress were work and combining work with family. Their main worries at work were: excessive workload and time constraints, especially being on call, organizational problems, and fear of harming patients. On-call workload correlated with burnout. Being frequently on call was correlated with severe stress symptoms--symptoms associated with sick leaves. Women were more affected by stress than men. High job control and organizational justice seemed to mitigate hospital-on-call stress symptoms. The respondents enjoyed fairly high job and life satisfaction. Job control and organizational justice were the most important correlates of these wellness indicators. Work-related factors were more important in males, whereas family life played a larger role in the well-being of female anesthesiologists. Women had less job control, fewer permanent job contracts, and a higher domestic workload. Of the respondents, 31% were willing to consider changing to another physician's specialty and 43% to a profession other than medicine. The most important correlates for these job turnover attitudes were conflicts at the workplace, low job control, organizational injustice, stress, and job dissatisfaction. One in four had at some time considered suicide. Respondents with poor health, low social support, and family problems were at the highest risk for suicidality. The highest risks at work were conflicts with co-workers and superiors, on-call-related stress symptoms, and low organizational justice. If a respondent had several risk factors, the risk for suicidality doubled with each additional factor. On-call work-burden, job control, fairness of decision-making procedures,and workplace relationships should be the focus in attempts to increase the work-related well-being of anesthesiologists.

Regulation of Kinin receptor Expression in Heart Failure with a Focus on Vascular Endothelium

Accumulating evidence show that kinins, notably bradykinin (BK) and kallidin, have cardioprotective effects. To these include reduction of left ventricular hypertrophy (LVH) and progression of heart failure. The effects are mediated through two G protein-coupled receptors- bradykinin type-2 receptor (BK-2R) and bradykinin type -1 receptor (BK-1R). The widely accepted cardioprotective effects of BK-receptors relate to triggering the production and release of vasodilating nitric oxide (NO) by endothelial cells. They also exert anti-proliferative effects on fibroblasts and anti-hypertrophic effects on myocytes, and thus may play an essential role in the cardioprotective response to myocardial injury. The role for BK-1Rs in HF is based on experimental animal models, where the receptors have been linked to cardioprotective- but also to cardiotoxic -effects. The BK-1Rs are induced under inflammatory and ischemic conditions, shown in animal models; no previous reports, concerning BK-1Rs in human heart failure, have been presented. The expression of BK-2Rs is down-regulated in human end-stage heart failure. Present results showed that, in these patients, the BK-1Rs were up-regulated, suggesting that also BK-1Rs are involved in the pathogenesis of human heart failure. The receptors were localized mainly in the endothelium of intramyocardial coronary vessels, and correlated with the increased TNF-α expression in the myocardial coronary vessels. Moreover, in cultured endothelial cells, TNF-α was a potent trigger of BK-1Rs. These results suggest that cytokines may be responsible for the up-regulation of BK-1Rs in human heart failure. A linear relationship between BK-2R mRNA and protein expression in normal and failing human left ventricles implies that the BK-2Rs are regulated on the transcriptional level, at least in human myocardium. The expression of BK-2Rs correlated positively with age in normal and dilated hearts (IDC). The results suggest that human hearts adapts to age-related changes, by up-regulating the expression of cardioprotective BK-2Rs. Also, in the BK-2R promoter polymorphism -58 T/C, the C-allele was accumulated in cardiomyopathy patients which may partially explain the reduced number of BK-2Rs. Statins reduce the level of plasma cholesterol, but also exert several non-cholesterol-dependent effects. These effects were studied in human coronary arterial endothelial cells (hCAEC) and incubation with lovastatin induced both BK-1 and BK-2Rs in a time and concentration-dependent way. The induced BK-2Rs were functionally active, thus NO production and cGMP signaling was increased. Induction was abrogated by mevalonate, a direct HMG-CoA metabolite. Lovastatin is known to inhibit Rho activation, and by a selective RhoA kinase inhibitor (Y27632), a similar induction of BK-2R expression as with lovastatin. Interestingly a COX-2-inhibitor (NS398) inhibited this lovastatin-induction of BK-2Rs, suggesting that COX-2 inhibitors may affect the endothelial BK-2Rs, in a negative fashion. Hypoxia is a common denominator in HF but also in other cardiovascular diseases. An induction of BK-2Rs in mild hypoxic conditions was shown in cultured hCAECs, which was abolished by a specific BK-2R inhibitor Icatibant. These receptors were functionally active, thus BK increased and Icatibant inhibited the production of NO. In rat myocardium the expression of BK-2R was increased in the endothelium of vessels, forming at the border zone, between the scar tissue and the healthy myocardium. Moreover, in in vitro wound-healing assay, endothelial cells were cultured under hypoxic conditions and BK significantly increased the migration of these cells and as Icatibant inhibited it. These results show, that mild hypoxia triggers a temporal expression of functionally active BK-2Rs in human and rat endothelial cells, supporting a role for BK-2Rs, in hypoxia induced angiogenesis. Our and previous results show, that BK-Rs have an impact on the cardiovascular diseases. In humans, at the end stage of heart failure, the BK-2Rs are down-regulated and BK-1Rs induced. Whether the up-regulation of BK-1Rs, is a compensatory mechanism against the down-regulation of BK-2Rs, or merely reflects the end point of heart failure, remains to bee seen. In a clinical point of view, the up-regulation of BK-2Rs, under hypoxic conditions or statin treatment, suggests that, the induction of BK-2Rs is protective in cardiovascular pathologies and those treatments activating BK-2Rs, might give additional tools in treating heart failure.

Studies of Immune Regulation in Type 1 Diabetes

Type 1 diabetes (T1D) is considered to be an autoimmune disease. In T1D insulin producing pancreatic β cells are destroyed. The disease process begins years before the clinical diagnosis of T1D. During the pathogenesis of T1D, pancreatic islets are infiltrated by cells of the immune system and T-lymphocytes are considered to be the main mediators of the β-cell destruction. In children with an active β-cell destruction process, autoantibodies against β-cell antigens appear in the blood. Individuals at increased risk of developing T1D can often be identified by detecting serum autoantibodies against β-cell antigens. Immunological aberrancies associated with T1D are related to defects in the polarization of T cells and in the function of regulatory mechanisms. T1D has been considered as an organ-specific autoimmune disease mediated by uncontrolled Th1-responses. In human T1D, the evidence for the role of over-expression of cytokines promoting cytotoxicity is controversial. For the past 15 years, regulatory T cells (Tregs) have been recognized as having a key role in the initiation and maintenance of tolerance, limiting harmful autoantigen-specific inflammation processes. It is possible that, if regulatory mechanisms fail to be initiated, the subtle inflammation targeting β cells lead to insulitis and eventually to overt T1D in some individuals. In the present thesis, we studied the induction of Tregs during the generation of T-cell responses in T1D. The results suggest that the generation of regulatory mechanisms and effector mechanisms upon T-cell activation is aberrant in children with T1D. In our studies, an in vitro cytotoxic environment inhibited the induction of genes associated with regulatory functions upon T-cell activation. We also found T1D patients to have an impaired cytotoxic response against coxsackievirus B4. Ineffective virus clearance may increase the apoptosis of β cells, and thus the risk of β-cell specific autoimmunity, due to the increased presentation of β-cell-derived peptides by APCs to T cells in pancreatic lymph nodes. Recently, a novel T helper cell subset called Th17 has been discovered. Animal models have associated Th17 cells and especially co-producers of IL-17 and IFN-γ with the pathogenesis of T1D. We aimed to characterize the role of Th17 immunity in human T1D. We demonstrated IL-17 activation to be a major alteration in T1D patients in comparison to healthy children. Moreover, alterations related to the FOXP3-mediated regulatory mechanisms were associated with the IL-17 up-regulation seen in T1D patients. These findings may have therapeutic implications for the treatment and prevention of T1D.

The Impact of Lifestyle and Cardiovascular Risk Factors in Midlife on the Health-Related Quality of Life among Old Men

Prevention of cardiovascular diseases is known to postpone death, but in an aging society it is important to ensure that those who live longer are neither disabled nor suffering an inferior quality of life. It is essential both from the point of view of the aging individual as well as that of society that any individual should enjoy a good physical, mental and social quality of life during these additional years. The studies presented in this thesis investigated the impact of modifiable risk factors, all of which affect cardiovascular health in the long term, on mortality and health-related quality of life (HRQoL). The data is based on the all male cohort of the Helsinki Businessmen Study. This cohort, originally of 3.490 men born between 1919 and 1934 has been followed since the 1960s. The socioeconomic status of the participants is similar, since all the men were working in leading positions. Extensive baseline examinations were conducted among 2.375 of the men in 1974 when their mean age was 48 and at this time the health, medication and cardiovascular risk factors of the participants were observed. In 2000, at the mean age of 73, the HRQoL of the survivors of the original cohort was examined using the RAND-36 mailed questionnaire (n=1.864). RAND-36, along with the equivalent SF-36, is the world s most widely used means of assessing generic health. The response rate was generally over 90%. Mortality was retrieved from national registers in 2000 and 2002. For the six substudies of this thesis, the impact of four different modifiable cardiovascular risk factors (weight gain, cholesterol, alcohol and smoking) on the HRQoL in old age was studied both independently and in combination. The follow-up time for these studies varies from 26 up to 39 years. Mortality is reported separately or included in the RAND-36 scores for HRQoL. Elevated levels of all the risk factors examined among the participants in midlife led to a diminished life expectancy. Among survivors, lower weight gain in midlife was associated with better HRQoL, both physically and mentally. Higher levels of serum cholesterol in middle age indicated both an earlier mortality and a decline in the physical component of HRQoL in a dose-response manner during the 39-year follow-up. Mortality was significantly higher in the highest baseline category of reported mean alcohol consumption (≥ 5 drinks/day), but fairly comparable in abstainers and moderate drinkers during the 29-year follow-up. When HRQoL in old age was accounted for mortality, the men with the highest alcohol consumption in midlife clearly had poorer physical and mental health in old age, but the HRQoL of abstainers and those who drank alcohol in moderation were comparatively similar. The amount of cigarette smoking in midlife was shown to have had a dose-response effect on both mortality and HRQoL in old age during the 26 year follow-up. The men smoking over 20 cigarettes daily in middle age lost about 10 years of their life-expectancy. Meanwhile, the physical functioning of surviving heavy smokers in old age was similar to men 10 years older in the general population. The impact of clustered cardiovascular risk factors was examined by comparing two subcohorts of men who were healthy in 1974, but with different baseline risk factor status. The men with low risk had a 50 % lower mortality during the 29-years follow-up. Their RAND-36 scores for the physical quality of life in old age were significantly better, and the 2002 questionnaire examining psychological well-being indicated also significantly better mental health among the low-risk group. The results indicate that different risk factor levels in midlife have a meaningful impact on life-expectancy and the quality of these extra years. Leading a healthy lifestyle improves both survival and the quality of life.

Hospital-related fears and coping strategies in 4-6-year-old children

There is only little information available on the 4-6-year-old child s hospital-related fears, and on the coping with such fears, as expressed by the children themselves. However, previous data collected from parents and hospital personnel indicate that hospitalization is an anxiety-producing experience for young children. The purpose of this study was to describe the experience of hospital-related fears and the experience of coping with hospital-related fears of 4-6-year-old children. The aim of this study was to form a descriptive model of the subjective experience of hospital-related fears and coping strategies of 4-6-year old children. The data were collected by interviewing 4-6-year-old children from a hospital and kindergarten settings in Finland from 2004 to 2006. Ninety children were interviewed in order to describe the hospital-related fear and the experience of fear, and 89 to describe their coping with the fear and the experience of coping. The children were chosen through purposive sampling. The data were gathered by semi-structured interview, supported by pictures. The data about hospital-related fears and on strategies for coping with hospital-related fears were reviewed by qualitative and quantitative methods. The experience of hospital-related fears and coping with these fears were analyzed using Colaizzi s Method of Phenomenological Analysis. The results revealed that more than 90 % of the children said they were afraid of at least one thing in hospital. Most of the fears could be categorized as nursing interventions, fears of being a patient, and fears caused by the developmental stage of the child. Children interviewed in the hospital expressed substantially more fears than children interviewed in kindergarten. Children s meanings of hospital-related fears were placed into four main clusters: 1) insecurity, 2) injury, 3) helplessness, 4) and rejection. The results also showed that children have plenty of coping strategies, to deal with their fears, especially such strategies in which the children themselves play an active role. Most often mentioned coping strategies were 1) the presence of parents and other family members, 2) the help of the personnel, 3) positive images and humour, 4) play, and 5) the child s own safety toy. The children interviewed in the hospital mentioned statistically significantly more often play, positive imagination and humour as their coping strategy than children interviewed in kindergarten. The meaning of coping with hospital fears consisted of six clusters: pleasure, security, care, understanding the meaning of the situation participating, and protecting oneself. Being admitted to a hospital is an event which may increase the fears of a 4-6-year-old child. Children who have personal experience of being admitted to a hospital describe more fears than healthy children in kindergarten. For young children, hospital-related fear can be such a distressing experience that it reflects on their feelings of security and their behaviour. Children can sometimes find it difficult to admit their fear. Children need the help of adults to express their hospital-related fears, the objects of the fears, and to cope with the fears. Personnel should be aware of children s fears and support them in the use of coping strategies. In addition to the experiences of security and care, pre-school-aged children need active coping strategies that they can use themselves, regardless of the presence of the parents or nurses. Most of all, children need the possibility to play and experience pleasure. Children can also be taught coping strategies which give them an active, positive role.

Health-Related Quality of Life, Costs and Treatment of Inflammatory Rheumatic Diseases in Routine Practice : With special emphasis on biological drugs

Rheumatoid arthritis (RA) and other chronic inflammatory joint diseases already begin to affect patients health-related quality of life (HRQoL) in the earliest phases of these diseases. In treatment of inflammatory joint diseases, the last two decades have seen new strategies and treatment options introduced. Treatment is started at an earlier phase; combinations of disease-modifying anti-rheumatic drugs (DMARDs) and corticosteroids are used; and in refractory cases new drugs such as tumour necrosis factor (TNF) inhibitors or other biologicals can be started. In patients with new referrals to the Department of Rheumatology of the Helsinki University Central Hospital, we evaluated the 15D and the Stanford Health Assessment Questionnaire (HAQ) results at baseline and approximately 8 months after their first visit. Altogether the analysis included 295 patients with various rheumatic diseases. The mean baseline 15D score (0.822, SD 0.114) was significantly lower than for the age-matched general population (0.903, SD 0.098). Patients with osteoarthritis (OA) and spondyloarthropathies (SPA) reported the poorest HRQoL. In patients with RA and reactive arthritis (ReA) the HRQoL improved in a statistically significant manner during the 8-month follow-up. In addition, a clinically important change appeared in patients with systemic rheumatic diseases. HAQ score improved significantly in patients with RA, arthralgia and fibromyalgia, and ReA. In a study of 97 RA patients treated either with etanercept or adalimumab, we assessed their HRQoL with the RAND 36-Item Health Survey 1.0 (RAND-36) questionnaire. We also analysed changes in clinical parameters and the HAQ. With etanercept and adalimumab, the values of all domains in the RAND-36 questionnaire increased during the first 3 months. The efficacy of each in improving HRQoL was statistically significant, and the drug effects were comparable. Compared to Finnish age- and sex-matched general population values, the HRQoL of the RA patients was significantly lower at baseline and, despite the improvement, remained lower also at follow-up. Our RA patients had long-standing and severe disease that can explain the low HRQoL also at follow-up. In a pharmacoeconomic study of patients treated with infliximab we evaluated medical and work disability costs for patients with chronic inflammatory joint disease during one year before and one year after institution of infliximab treatment. Clinical and economic data for 96 patients with different arthritis diagnoses showed, in all patients, significantly improved clinical and laboratory variables. However, the medical costs increased significantly during the second period by 12 015 (95% confidence interval, 6 496 to 18 076). Only a minimal decrease in work disability costs occurred mean decrease 130 (-1 268 to 1 072). In a study involving a switch from infliximab to etanercept, we investigated the clinical outcome in 49 patients with RA. Reasons for switching were in 42% failure to respond by American College of Rheumatology (ACR) 50% criteria; in 12% adverse event; and in 46% non-medical reasons although the patients had responded to infliximab. The Disease Activity Score with 28 joints examined (DAS28) allowed us to measure patients disease activity and compare outcome between groups based on the reason for switching. In the patients in whom infliximab was switched to etanercept for nonmedical reasons, etanercept continued to suppress disease activity effectively, and 1-year drug survival for etanercept was 77% (95% CI, 62 to 97). In patients in the infliximab failure and adverse event groups, DAS28 values improved significantly during etanercept therapy. However, the 1-year drug survival of etanercept was only 43% (95% CI, 26 to 70) and 50% (95% CI, 33 to 100), respectively. Although the HRQoL of patients with inflammatory joint diseases is significantly lower than that of the general population, use of early and aggressive treatment strategies including TNF-inhibitors can improve patients HRQoL effectively. Further research is needed in finding new treatment strategies for those patients who fail to respond or lose their response to TNF-inhibitors.

Genetic background of bipolar disorder and related cognitive impairments

Bipolar disorder (BP) is a complex psychiatric disorder characterized by episodes of mania and depression. BP affects approximately 1% of the world’s population and shows no difference in lifetime prevalence between males and females. BP arises from complex interactions among genetic, developmental and environmental factors, and it is likely that several predisposing genes are involved in BP. The genetic background of BP is still poorly understood, although intensive and long-lasting research has identified several chromosomal regions and genes involved in susceptibility to BP. This thesis work aims to identify the genetic variants that influence bipolar disorder in the Finnish population by candidate gene and genome-wide linkage analyses in families with many BP cases. In addition to diagnosis-based phenotypes, neuropsychological traits that can be seen as potential endophenotypes or intermediate traits for BP were analyzed. In the first part of the thesis, we examined the role of the allelic variants of the TSNAX/DISC1 gene cluster to psychotic and bipolar spectrum disorders and found association of distinct allelic haplotypes with these two groups of disorders. The haplotype at the 5’ end of the Disrupted-in-Schizophrenia-1 gene (DISC1) was over-transmitted to males with psychotic disorder (p = 0.008; for an extended haplotype p = 0.0007 with both genders), whereas haplotypes at the 3’ end of DISC1 associated with bipolar spectrum disorder (p = 0.0002; for an extended haplotype p = 0.0001). The variants of these haplotypes also showed association with different cognitive traits. The haplotypes at the 5’ end associated with perseverations and auditory attention, while the variants at the 3’ end associated with several cognitive traits including verbal fluency and psychomotor processing speed. Second, in our complete set of BP families with 723 individuals we studied six functional candidate genes from three distinct signalling systems: serotonin-related genes (SLC6A4 and TPH2), BDNF -related genes (BDNF, CREB1 and NTRK2) and one gene related to the inflammation and cytokine system (P2RX7). We replicated association of the functional variant Val66Met of BDNF with BP and better performance in retention. The variants at the 5’ end of SLC6A4 also showed some evidence of association among males (p = 0.004), but the widely studied functional variants did not yield any significant results. A protective four-variant haplotype on P2RX7 showed evidence of association with BP and executive functions: semantic and phonemic fluency (p = 0.006 and p = 0.0003, respectively). Third, we analyzed 23 bipolar families originating from the North-Eastern region of Finland. A genome-wide scan was performed using the 6K single nucleotide polymorphism (SNP) array. We identified susceptibility loci at chromosomes 7q31 with a LOD score of 3.20 and at 9p13.1 with a LOD score of 4.02. We followed up both linkage findings in the complete set of 179 Finnish bipolar families. The finding on chromosome 9p13 was supported (maximum LOD score of 3.02), but the susceptibility gene itself remains unclarified. In the fourth part of the thesis, we wanted to test the role of the allelic variants that have associated with bipolar disorder in recent genome-wide association studies (GWAS). We could confirm findings for the DFNB31, SORCS2, SCL39A3, and DGKH genes. The best signal in this study comes from DFNB31, which remained significant after multiple testing corrections. Two variants of SORCS2 were allelic replications and presented the same signal as the haplotype analysis. However, no association was detected with the PALB2 gene, which was the most significantly associated region in the previous GWAS. Our results indicate that BP is heterogeneous and its genetic background may accordingly vary in different populations. In order to fully understand the allelic heterogeneity that underlies common diseases such as BP, complete genome sequencing for many individuals with and without the disease is required. Identification of the specific risk variants will help us better understand the pathophysiology underlying BP and will lead to the development of treatments with specific biochemical targets. In addition, it will further facilitate the identification of environmental factors that alter risk, which will potentially provide improved occupational, social and psychological advice for individuals with high risk of BP.

Development of Novel Assays for Measuring Different Molecular Forms of Prostate Specific Antigen

Prostate cancer (PCa) is the most commonly diagnosed non-skin cancer and second leading cause of cancer-related death of men in developed countries. Measurement of prostate specific antigen (PSA) is a very sensitive method for diagnosing and monitoring of prostate cancer (PCa), but the specificity needs improvement. Measurements of different molecular forms of PSA have been shown to improve differentiation between PCa and benign prostatic diseases. However, accurate measurement of some isoforms has not been achieved in previous assays. The aim of the present study was to develop new assays that reliably measure enzymatically active PSA, PSA-α1-chymotryposin (PSA-ACT) and PSA-α1-protease inhibitor (PSA-API), and to evaluate their diagnostic value. Double-label immunofluorometric assays using a novel monoclonal antibody (MAb) and another antibody to either free PSA (fPSA) or total PSA (tPSA) were developed and used to measure PSA-ACT and fPSA or tPSA at the same time. These assays provide enough sensitivity for measurement of PSA-ACT in sera with low PSA levels. The results obtained confirmed that proportion of PSA-ACT to tPSA (%PSA-ACT) was as useful as proportion of fPSA to tPSA (%fPSA) for discrimination between PCa and benign prostatic hyperplasia (BPH). We developed an immunoassay for detection of PSA-API based on proximity ligation, which improved assay sensitivity 10-fold compared with conventional assays. Our results confirmed previous findings that the PSA-API level is somewhat lower in men with than without PCa, and the combination of %fPSA and proportion of PSA-API to tPSA (%PSA-API) provides diagnostic improvement compared with either method alone. Assays based on this principle should be applicable to other immunoassays in which the nonspecific background is a problem. An immunopeptidometric sandwich assay (IPMA) was developed to measure the enzymatically active PSA. This assay showed high specificity, but sensitivity was not good enough for measurement of PSA concentrations in the gray zone, 2-10 µg/L, in which tPSA does not efficiently differentiate between PCa and BPH. We further developed a solid-phase proximity ligation immunoassay, which provided a 10-fold improvement in sensitivity. This proof of concept study shows that peptides reacting with proteins are potentially useful for sensitive and specific measurement of protein variants for which specific MAbs cannot be obtained.

Genistein and 17β-estradiol fatty acid esters in blood and adipose tissue and the structure-related antioxidant activity of estrogens on lipoproteins

Soy-derived phytoestrogen genistein and 17β-estradiol (E2), the principal endogenous estrogen in women, are also potent antioxidants protecting LDL and HDL lipoproteins against oxidation. This protection is enhanced by esterification with fatty acids, resulting in lipophilic molecules that accumulate in lipoproteins or fatty tissues. The aims were to investigate, whether genistein becomes esterified with fatty acids in human plasma accumulating in lipoproteins, and to develop a method for their quantitation; to study the antioxidant activity of different natural and synthetic estrogens in LDL and HDL; and to determine the E2 esters in visceral and subcutaneous fat in late pregnancy and in pre- and postmenopause. Human plasma was incubated with [3H]genistein and its esters were analyzed from lipoprotein fractions. Time-resolved fluoroimmunoassay (TR-FIA) was used to quantitate genistein esters in monkey plasma after subcutaneous and oral administration. The E2 esters in women s serum and adipose tissue were also quantitated using TR-FIA. The antioxidant activity of estrogen derivatives (n=43) on LDL and HDL was assessed by monitoring the copper induced formation of conjugated dienes. Human plasma was shown to produce lipoprotein-bound genistein fatty acid esters, providing a possible explanation for the previously reported increased oxidation resistance of LDL particles during intake of soybean phytoestrogens. Genistein esters were introduced into blood by subcutaneous administration. The antioxidant effect of estrogens on lipoproteins is highly structure-dependent. LDL and HDL were protected against oxidation by many unesterified, yet lipophilic derivatives. The strongest antioxidants had an unsubstituted A-ring phenolic hydroxyl group with one or two adjacent methoxy groups. E2 ester levels were high during late pregnancy. The median concentration of E2 esters in pregnancy serum was 0.42 nmol/l (n=13) and in pre- (n=8) and postmenopause (n=6) 0.07 and 0.06 nmol/l, respectively. In pregnancy visceral fat the concentration of E2 esters was 4.24 nmol/l and in pre- and postmenopause 0.82 and 0.74 nmol/l. The results from subcutaneous fat were similar. In serum and fat during pregnancy, E2 esters constituted about 0.5 and 10% of the free E2. In non-pregnant women most of the E2 in fat was esterified (the ester/free ratio 150 - 490%). In postmenopause, E2 levels in fat highly exceeded those in serum, the majority being esterified. The pathways for fatty acid esterification of steroid hormones are found in organisms ranging from invertebrates to vertebrates. The evolutionary preservation and relative abundance of E2 esters, especially in fat tissue, suggest a biological function, most likely in providing a readily available source of E2. The body s own estrogen reservoir could be used as a source of E2 by pharmacologically regulating the E2 esterification or hydrolysis.