Bone Health in Children and Adolescents with Juvenile Idiopathic Arthritis and Solid Organ Transplant

Osteoporosis is a skeletal disorder characterized by compromised bone strength that predisposes to increased fracture risk. Childhood and adolescence are critical periods for bone mass gain. Peak bone mass is mostly acquired by the age of 18 years and is an important determinant of adult bone health and lifetime risk for fractures. Medications, especially glucocorticoids (GCs), chronic inflammation, decreased physical activity, hormonal deficiencies, delayed puberty, and poor nutrition may predispose children and adolescents with a chronic disease to impaired bone health. In this work, we studied overall bone health, the incidence and prevalence of fractures in children and adolescents who were treated for juvenile idiopathic arthritis (JIA) or had undergone solid organ transplantation. The first study cohort included 62 patients diagnosed with JIA and treated with GCs. The epidemiology of fractures after transplantation was investigated in 196 patients and a more detailed analysis of bone health determinants was performed on 40 liver (LTx) and 106 renal (RTx) transplantation patients. Bone mineral density (BMD) and vertebral morphology were assessed by dual-energy x-ray absorptiometry. Standard radiographs were obtained to detect vertebral fractures and to determine bone age; BMD values were adjusted for skeletal maturity. Our study showed that median BMD values were subnormal in all patient cohorts. The values were highest in patients with JIA and lowest in patients with LTx. Age at transplantation influenced BMD values in LTx but not RTx patients; BMD values were higher in patients who had LTx before the age of two years. BMD was lowest during the immediate posttransplantation years and increased subnormally during puberty. Delayed skeletal maturation was common in all patient groups. The prevalence of vertebral fractures ranged from 10% to 19% in the cohorts. Most of the fractures were asymptomatic and diagnosed only at screening. Vertebral fractures were most common in LTx patients. Vitamin D deficiency was common in all patient groups, and only 3% of patients with JIA and 25% of transplantation patients were considered to have adequate serum vitamin D levels. The total cumulative weight-adjusted dose of GC was not associated with BMD values in JIA or LTx patients. The combination of female gender and age over 15 years, parathyroid hormone concentration over 100 ng/L, and cumulative weight-adjusted methylprednisolone dose over 150 mg/kg during the three preceding years were found to be important predictors for low lumbar spine BMD in RTx patients. Based on the high prevalence of osteoporosis in the study cohorts more efforts should be put to prevention and early diagnosis of osteoporosis in these pediatric patients.

Inhibition of CYP1A2-mediated drug metabolism in vitro and in humans : With special emphasis on rofecoxib and other NSAIDs

The cytochrome P450 1A2 (CYP1A2) is one of the major metabolizing enzymes. The muscle relaxant tizanidine is a selective substrate of CYP1A2, and the non-steroidal anti-inflammatory drug (NSAID) rofecoxib was thought to modestly in-hibit it. Cases suggesting an interaction between tizanidine and rofecoxib had been reported, but the mechanism was unknown. Also other NSAIDs are often used in combination with muscle relaxants. The aims of this study were to investigate the effect of rofecoxib, several other NSAIDs and female sex steroids on CYP1A2 ac-tivity in vitro and in vivo, and to evaluate the predictability of in vivo inhibition based on in vitro data. In vitro, the effect of several NSAIDs, female sex steroids and model inhibitors on CYP1A2 activity was studied in human liver microsomes, without and with preincubation. In placebo controlled, cross-over studies healthy volunteers ingested a single dose of tizanidine after a pretreament with the inhibitor (rofecoxib, tolfenamic acid or celecoxib) or placebo. Plasma (and urine) concentrations of tizanidine and its metabolites were measured, and the pharmacodynamic effects were recorded. A caffeine test was also performed. In vitro, fluvoxamine, tolfenamic acid, mefenamic acid and rofecoxib potently in-hibited CYP1A2. Ethinylestradiol, celecoxib, desogestrel and zolmitriptan were moderate, and etodolac, ciprofloxacin, etoricoxib and gestodene were weak inhibi-tors of CYP1A2. At 100 µM, other tested NSAIDs and steroids inhibited CYP1A2 less than 35%. Rofecoxib was found to be a mechanism-based inhibitor of CYP1A2. In vivo, rofecoxib greatly increased the plasma concentrations (over ten-fold) and the pharmacodynamic effects of tizanidine. Also the metabolism of caf-feine was impaired by rofecoxib. Despite the relatively strong in vitro CYP1A2 inhibitory effects, tolfenamic acid and celecoxib did not have a significant effect on tizanidine and caffeine concentrations in humans. Competitive inhibition model and the free plasma concentration of the inhibitor predicted well the effect of fluvoxam-ine and the lack of effect of tolfenamic acid and celecoxib on tizanidine concentra-tions in humans, and mechanism-based inhibition model explained the effects of rofecoxib. However, the effects of ciprofloxacin and oral contraceptives were un-derestimated from the in vitro data. Rofecoxib is a potent mechanism-based inhibitor of CYP1A2 in vitro and in vivo. This mechanism may be involved in the adverse cardiovascular effects of rofecoxib. Tolfenamic acid and celecoxib seem to be safe in combination with tizanidine, but mefenamic acid might have some effect on tizanidine concentrations in vivo. Con-sidering the mechanism of inhibition, and using the free plasma concentration of the inhibitor, many but not all CYP1A2 interactions can be predicted from in vitro data.

Fertility in Namibia : Changes in fertility levels in North-Central Namibia 1960-2001, including an assessment of the impact of HIV

The aim of this study was to estimate the development of fertility in North-Central Namibia, former Ovamboland, from 1960 to 2001. Special attention was given to the onset of fertility decline and to the impact of the HIV epidemic on fertility. An additional aim was to introduce parish registers as a source of data for fertility research in Africa. Data used consisted of parish registers from Evangelical Lutheran congregations, the 1991 and 2001 Population and Housing Censuses, the 1992 and 2000 Namibia Demographic and Health Surveys, and the HIV sentinel surveillances of 1992-2004. Both period and cohort fertility were analysed. The P/F ratio method was used when analysing census data. The impact of HIV infection on fertility was estimated indirectly by comparing the fertility histories of women who died at an age of less than 50 years with the fertility of other women. The impact of the HIV epidemic on fertility was assessed both among infected women and in the general population. Fertility in the study population began to decline in 1980. The decline was rapid during the 1980s, levelled off in the early 1990s at the end of war of independence and then continued to decline until the end of the study period. According to parish registers, total fertility was 6.4 in the 1960s and 6.5 in the 1970s, and declined to 5.1 in the 1980s and 4.2 in the 1990s. Adjustment of these total fertility rates to correspond to levels of fertility based on data from the 1991 and 2001 censuses resulted in total fertility declining from 7.6 in 1960-79 to 6.0 in 1980-89, and to 4.9 in 1990-99. The decline was associated with increased age at first marriage, declining marital fertility and increasing premarital fertility. Fertility among adolescents increased, whereas the fertility of women in all other age groups declined. During the 1980s, the war of independence contributed to declining fertility through spousal separation and delayed marriages. Contraception has been employed in the study region since the 1980s, but in the early 1990s, use of contraceptives was still so limited that fertility was higher in North-Central Namibia than in other regions of the country. In the 1990s, fertility decline was largely a result of the increased prevalence of contraception. HIV prevalence among pregnant women increased from 4% in 1992 to 25% in 2001. In 2001, total fertility among HIV-infected women (3.7) was lower than that among other women (4.8), resulting in total fertility of 4.4 among the general population in 2001. The HIV epidemic explained more than a quarter of the decline in total fertility at population level during most of the 1990s. The HIV epidemic also reduced the number of children born by reducing the number of potential mothers. In the future, HIV will have an extensive influence on both the size and age structure of the Namibian population. Although HIV influences demographic development through both fertility and mortality, the effect through changes in fertility will be smaller than the effect through mortality. In the study region, as in some other regions of southern Africa, a new type of demographic transition is under way, one in which population growth stagnates or even reverses because of the combined effects of declining fertility and increasing mortality, both of which are consequences of the HIV pandemic.

Sex steroids in Sjögren's syndrome

Sjögren s syndrome (SS) is a strongly female dominant autoimmune disease. SS targets mainly salivary and lacrimal glands and leads to loss of the secreting acinar cells of these glands. Accordingly, secretion of the affected glands is diminished and the main symptoms of SS, dryness of mouth and eyes, follow. In addition to these sicca symptoms, SS patients suffer from severe fatigue and can have various extraglandular symptoms. To date, the etiology of SS still remains unknown. Female dominance and the late onset of the disease simultaneously with remarkable hormonal changes in the body (menopause, adrenopause) encouraged us to hypothesize that sex steroids, especially androgens, are involved in the onset and progression of SS. We confirmed our hypothesis and showed that patients with SS suffer from androgen depletion both systemically and locally in the target tissue of SS, salivary glands. We especially focused on the local androgen environment in salivary glands and demonstrated that healthy salivary glands contain a complete enzymatic machinery for local synthesis of androgens and estrogens from pro-hormone dehydroepiandrosterone (DHEA). However, in SS salivary glands the enzymes catalyzing the local androgen synthesis are defective and, in a subgroup of patients, practically non-functional. Probably due to this local defect in DHEA processing, therapy with DHEA was found unbeneficial for SS patients in the treatment of fatigue. We also studied the effect of the local androgen depletion on salivary glands. We found that in salivary gland cells and healthy labial salivary glands androgens upregulate integrin subunits α1 and α2, which are important for the communication, differentiation and function of the acinar cells. On the contrary, in SS salivary glands DHEA failed to upregulate these signaling molecules, again probably due to defective processing of DHEA into active androgens. Our finding highlights the importance of the local androgen environment and local DHEA processing for the function and welfare of salivary glands. In conclusion, this study showed that patients with SS are androgen depleted both systemically and locally in salivary glands. SS patients also have a defective local sex steroid synthesizing enzymatic machinery further impairing the local androgen depletion. We also showed that the local androgen defect leads to decreased expression of acinar cell specific integrin molecules, which impairs the signaling between the acinar cells and basement membrane and might thus explain the acinar cell loss seen in SS salivary glands. By showing the importance of the local sex steroid imbalance in SS we have clarified some etiopathogenetic mechanisms of SS, which have thus far remained unknown.

Crosstalk between the sympathetic nervous system, inflammation and coagulation in gestational diabetes; a therapeutic approach in postmenopausal hypertension

The occurrence of gestational diabetes (GDM) during pregnancy is a powerful sign of a risk of later type 2 diabetes (T2D) and cardiovascular diseases (CVDs). The physiological basis for this disease progression is not yet fully understood, but increasing evidence exists on interplay of insulin resistance, subclinical inflammation, and more recently, on unbalance of the autonomic nervous system. Since the delay in development of T2D and CVD after GDM ranges from years to decades, better understanding of the pathophysiology of GDM could give us new tools for primary prevention. The present study was aimed at investigating the role of the sympathetic nervous system (SNS) in GDM and its associations with insulin and a variety of inflammatory cytokines and coagulation and fibrinolysis markers. This thesis covers two separate study lines. Firstly, we investigated 41 women with GDM and 22 healthy pregnant and 14 non-pregnant controls during the night in hospital. Blood samples were drawn at 24:00, 4:00 and 7:00 h to determine the concentrations of plasma glucose, insulin, noradrenaline (NA) and adrenomedullin, markers of subclinical inflammation, coagulation and fibrinolysis variables and platelet function. Overnight holter ECG recording was performed for analysis of heart rate variability (HRV). Secondly, we studied 87 overweight hypertensive women with natural menopause. They were randomised to use a central sympatholytic agent, moxonidine (0.3mg twice daily), the β-blocking agent atenolol (50 mg once daily+blacebo once daily) for 8 weeks. Inflammatory markers and adiponectin were analysed at the beginning and after 8 weeks. Activation of the SNS (increase in NA, decreased HRV) was seen in pregnant vs. non-pregnant women, but no difference existed between GDM and normal pregnancy. However, modulation (internal rhythm) of HRV was attenuated in GDM. Insulin and inflammatory cytokine levels were comparable in all pregnant women but nocturnal variation of concentrations of C-reactive protein, serum amyloid A and insulin were reduced in GDM. Levels of coagulation factor VIII were lower in GDM compared with normal pregnancy, whereas no other differences were seen in coagulation and fibrinolysis markers. No significant associations were seen between NA and the studied parameters. In the study of postmenopausal women, moxonidine treatment was associated with favourable changes in the inflammatory profile, seen as a decrease in TNFα concentrations (increase in atenolol group) and preservation of adiponectin levels (decrease in atenolol group). In conclusion, our results did not support our hypotheses of increased SNS activity in GDM or a marked association between NA and inflammatory and coagulation markers. Reduced biological variation of HRV, insulin and inflammatory cytokines suggests disturbance of autonomic and hormonal regulatory mechanisms in GDM. This is a novel finding. Further understanding of the regulatory mechanisms could allow earlier detection of risk women and the possibility of prevention. In addition, our results support consideration of the SNS as one of the therapeutic targets in the battle against metabolic diseases, including T2D and CVD.