oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Search Results: 1 - 10 of 1201 matches for " Katharina Main "
All listed articles are free for downloading (OA Articles)
Page 1 /1201
Display every page Item
Normal Sweat Secretion Despite Impaired Growth Hormone-Insulin-Like Growth Factor-I Axis in Obese Subjects
Michael H?jby Rasmussen,Anders Juul,Katharina M. Main,Jannik Hilsted
International Journal of Endocrinology , 2011, DOI: 10.1155/2011/493840
Abstract: Adults with GH deficiency are known to exhibit reduced sweating. Whether sweating capacity is impacted in obese subjects with impaired GH secretion have not previously been investigated. The main objective was to investigate sweat secretion rate and the GH-IGF-I axis in obese subjects before and after weight loss. Sixteen severely obese women (BMI, 40.6 ± 1.1?kg/m2) were investigated before and after a diet-induced weight loss. Sixteen age-matched nonobese women served as controls. The obese subjects presented the characteristic decreased GH release, hyperinsulinaemia, increased FFA levels, and impaired insulin sensitivity, which all were normalised after diet-induced weight loss of 30 ± 5?kg. Sweat secretion rates were similar comparing obese and nonobese subjects (78 ± 10 versus 82 ± 9?mg/30 minutes) and sweat secretion did not change after a diet-induced weight loss in obese subjects. We conclude that although obese subjects have markedly reduced GH release and impaired IGF-I levels, sweat secretion rate is found to be normal. 1. Introduction Sweating capacity as measured by sweat secretion rates has been reported reduced in adult patients with GH deficiency [1–4] as well as in children with GH deficiency (GHD) and GH insensitivity syndromes [5, 6]. Furthermore, sweat secretion has been found correlated to circulating IGF-I levels [1, 4, 7], and GH deficiency have been reported to have a profound effect on thermoregulation [2, 8]. These observations in patients with GHD suggest that GH have a role in thermal regulation, via an effect on sweating capacity, and the reduced sweating is part of the abnormalities observed in patients with GHD [7, 9], as well as that some of the positive effects reported following GH replacement therapy might be due to a normalization of sweat secretion [7]. Normal sweating is of importance for maintaining correct temperature regulation and if disturbed can cause significant discomfort. The mechanism of GH action on sweating is not clear; however, GH receptors have been demonstrated on sweat glands, and GH may function as a trophic factor for sweat glands [10]. It has been suggested that GH hyper- and hyposecretory states result in changes in the growth and metabolic status of sweat glands, with alterations in sweat gland innervation [4] and a reduced number of sweat glands has been reported in adults with GHD [11]. Adults with GHD are characterised by perturbations in body composition, lipid metabolism, and cardiovascular risk profile [12]. It is well established that adult GHD usually is accompanied by an increase in fat
Do Thyroid Disrupting Chemicals Influence Foetal Development during Pregnancy?
Marie-Louise Hartoft-Nielsen,Malene Boas,Sofie Bliddal,?ase Krogh Rasmussen,Katharina Main,Ulla Feldt-Rasmussen
Journal of Thyroid Research , 2011, DOI: 10.4061/2011/342189
Abstract: Maternal euthyroidism during pregnancy is crucial for normal development and, in particular, neurodevelopment of the foetus. Up to 3.5 percent of pregnant women suffer from hypothyroidism. Industrial use of various chemicals—endocrine disrupting chemicals (EDCs)—has been shown to cause almost constant exposure of humans with possible harmful influence on health and hormone regulation. EDCs may affect thyroid hormone homeostasis by different mechanisms, and though the effect of each chemical seems scarce, the added effects may cause inappropriate consequences on, for example, foetal neurodevelopment. This paper focuses on thyroid hormone influence on foetal development in relation to the chemicals suspected of thyroid disrupting properties with possible interactions with maternal thyroid homeostasis. Knowledge of the effects is expected to impact the general debate on the use of these chemicals. However, more studies are needed to elucidate the issue, since human studies are scarce. 1. Introduction Maintaining maternal euthyroidism during pregnancy is important for growth and development, in particular neurodevelopment of the foetus. Even subtle changes in thyroid function of the pregnant woman can cause detrimental effects for the foetus [1–5]. In the first trimester, the foetus relies solely on the thyroid hormones thyroxine (T4) and tri-iodothyronine (T3) and iodine from the mother. Later in pregnancy and during lactation, maternal thyroid hormones still contribute significantly to foetal thyroid homeostasis [6–8]. Worldwide, both overt and subclinical hypothyroidism are frequent among fertile women [9–14]. Prior maternal thyroid diseases as well as iodine and selenium deficiencies are known risk factors for hypothyroidism. Abundant industrial and household use of various chemicals—called endocrine disrupting chemicals (EDCs)—expose humans with potential harmful influences on health and hormone regulation. As recently reviewed, several of these EDCs have been found to have thyroid disrupting properties as well [15–17]. Probably each chemical has limited thyroid disruptive effects at environmental exposure doses. However, the combined influence of several chemicals through different pathways of thyroid hormone synthesis and action may have significant impact on both maternal and foetal thyroid function [18, 19] and, thus, a potential to compromise foetal development and maturation. This paper will focus on the influence of thyroid hormones on foetal development in relation to the chemicals suspected to have thyroid disrupting properties. Knowledge on
Challenges in Interpretation of Thyroid Function Tests in Pregnant Women with Autoimmune Thyroid Disease
Ulla Feldt-Rasmussen,Anne-Sofie Bliddal Mortensen,?se Krogh Rasmussen,Malene Boas,Linda Hilsted,Katharina Main
Journal of Thyroid Research , 2011, DOI: 10.4061/2011/598712
Abstract: Physiological changes during gestation are important to be aware of in measurement and interpretation of thyroid function tests in women with autoimmune thyroid diseases. Thyroid autoimmune activity is decreasing in pregnancy. Measurement of serum TSH is the first-line screening variable for thyroid dysfunction also in pregnancy. However, using serum TSH for control of treatment of maternal thyroid autoimmunity infers a risk for compromised foetal development. Peripheral thyroid hormone values are highly different among laboratories, and there is a need for laboratory-specific gestational age-related reference ranges. Equally important, the intraindividual variability of the thyroid hormone measurements is much narrower than the interindividual variation (reflecting the reference interval). The best laboratory assessment of thyroid function is a free thyroid hormone estimate combined with TSH. Measurement of antithyroperoxidase and/or TSH receptor antibodies adds to the differential diagnosis of autoimmune and nonautoimmune thyroid diseases. 1. Introduction Diagnosing maternal thyroid dysfunction during all stages of pregnancy is very important for the outcome for both mother and foetus [1, 2]. Women with hypothyroidism treated insufficiently with levothyroxine (high serum concentration of thyrotropin (TSH) or serum free thyroxine (T4) in the low normal range) deliver babies with significantly lower IQ and/or other inhibited neuropsychological development [3, 4]. Such offspring outcome has even been demonstrated in women with a serum concentration of T4 in the low normal range during pregnancy [5]. Prevalence of autoimmune thyroid disease (AITD) is high in women of reproductive age, whether or not they are pregnant [6]. AITD not only affects fertility [6], but may also lead to a decreased thyroid reserve with decreased availability of thyroxine. This is particularly important in the first half of pregnancy, in which the foetal development depends on the delivery of thyroxine from the mother [7, 8]. Although autoimmune thyrotoxicosis, Graves’ disease, is rare in pregnant women, transfer of TSH receptor antibodies, which can be either stimulating or blocking, may give rise to foetal and neonatal thyrotoxicosis or hypothyroidism, respectively [9, 10]. As a natural consequence of the importance of thyroid hormones for foetal brain development much focus has been given to diagnosing both overt and subclinical (or mild) thyroid dysfunction as early as possible in pregnant women, recently resulting in international consensus guidelines [10]. Although the
Pathological and Incidental Findings on Brain MRI in a Single-Center Study of 229 Consecutive Girls with Early or Precocious Puberty
Signe Sloth Mogensen, Lise Aksglaede, Annette Mouritsen, Kaspar S?rensen, Katharina M. Main, Peter Gideon, Anders Juul
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029829
Abstract: Central precocious puberty may result from organic brain lesions, but is most frequently of idiopathic origin. Clinical or biochemical factors which could predict a pathological brain MRI in girls with CPP have been searched for. With the recent decline in age at pubertal onset among US and European girls, it has been suggested that only girls with CPP below 6 years of age should have brain MRI performed. Objective To evaluate the outcome of brain MRI in girls referred with early signs of puberty in relation to age at presentation as well as clinical and biochemical parameters. Method A single-center study of 229 consecutive girls with early or precocious puberty who had brain imaging performed. We evaluated medical history, clinical and biochemical factors, and four groups were defined based on the outcome of their MRI. Results Thirteen out of 208 (6.3%) girls with precocious puberty, but no other sign of CNS symptoms, had a pathological brain MRI. Importantly, all 13 girls were above 6 years of age, and 6 girls were even 8–9 years old. Twenty girls (9.6%) had incidental findings on brain MRI. Furthermore, 21 girls had known CNS pathology at time of evaluation. Basal LH was significantly higher in girls with newly diagnosed CNS pathology compared to girls with a non-pathological MRI (p = 0.025); no cut of value was found as values overlapped. Conclusion A high frequency of 6–8 year old girls with precocious puberty in our study had a pathological brain MRI, which could not be predicted from any clinical nor biochemical parameters. Thus, we believe that girls with precocious pubertal development of central origin before 8 years of age should continue to be examined by a brain MRI.
Opinion Leaders and Lead Users in Marketing and Management Accounting and Impact on Small Business Performance  [PDF]
Katharina Simbeck
Social Networking (SN) , 2013, DOI: 10.4236/sn.2013.21002
Abstract: This paper empirically investigates into the business performance benefit that lead users or opinion leaders among small business owners draw from their higher involvement in management accounting or marketing topics. This work also contributes to a better identification of network members’ roles solely through their ties between each other. Indeed, lead users and opinion leaders can be differentiated by a higher degree centrality in comparison to their peers. However, being an opinion leader or a lead user does not yield a measurable business benefit to the small businesses studied in this sample.
Risk Factors for Congenital Cryptorchidism in a Prospective Birth Cohort Study
Ida N. Damgaard, Tina K. Jensen, The Nordic Cryptorchidism Study Group , J?rgen H. Petersen, Niels E. Skakkeb?k, Jorma Toppari, Katharina M. Main
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003051
Abstract: Background Risk factors for congenital cryptorchidism were investigated in a prospective birth cohort study in Denmark and Finland from 1997 to 2001. Methodology and Principal Findings In total, 2,496 boys were examined for cryptorchidism at birth (cryptorchid/healthy: 128/2,368) and three months old (33/2,215). Information on risk factors was obtained antenatally (questionnaire/interview) or at birth from birth records. Use of nicotine substitutes during pregnancy (n = 40) and infertility treatment by intrauterine insemination (n = 49) were associated with an increased risk for cryptorchidism, adjusted odds ratio (95% confidence interval) (OR (95%CI)) 3.04 (95%CI 1.00–9.27) and 3.01 (95%CI 1.27–7.15), respectively. No association was seen for mothers (n = 79) who had infertility treatment in form of intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF) treatment (OR 0.71 95%CI 0.21–2.38). In total, 728 (29%) reported to have smoked during pregnancy, however, no increased risk among maternal smokers was found. Furthermore, we found statistically significant associations between cryptorchidism and low birth weight, prematurity, being small for gestational age, substantial vaginal bleeding, and breech presentation, which are in accordance with other studies. Conclusions and Significance Our study revealed two novel risk factors for cryptorchidism: intrauterine insemination and the use of nicotine substitutes in pregnancy. This suggests that cryptorchidism may not only be associated to genetic factors, but also to maternal lifestyle and exposure.
Paraoxonase 1 Polymorphism and Prenatal Pesticide Exposure Associated with Adverse Cardiovascular Risk Profiles at School Age
Helle R. Andersen, Christine Wohlfahrt-Veje, Christine Dalg?rd, Lene Christiansen, Katharina M. Main, Christine Nellemann, Katsuyuki Murata, Tina K. Jensen, Niels E. Skakkeb?k, Philippe Grandjean
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036830
Abstract: Background Prenatal environmental factors might influence the risk of developing cardiovascular disease later in life. The HDL-associated enzyme paraoxonase 1 (PON1) has anti-oxidative functions that may protect against atherosclerosis. It also hydrolyzes many substrates, including organophosphate pesticides. A common polymorphism, PON1 Q192R, affects both properties, but a potential interaction between PON1 genotype and pesticide exposure on cardiovascular risk factors has not been investigated. We explored if the PON1 Q192R genotype affects cardiovascular risk factors in school-age children prenatally exposed to pesticides. Methods Pregnant greenhouse-workers were categorized as high, medium, or not exposed to pesticides. Their children underwent a standardized examination at age 6-to-11 years, where blood pressure, skin folds, and other anthropometric parameters were measured. PON1-genotype was determined for 141 children (88 pesticide exposed and 53 unexposed). Serum was analyzed for insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGFBP3), insulin and leptin. Body fat percentage was calculated from skin fold thicknesses. BMI results were converted to age and sex specific Z-scores. Results Prenatally pesticide exposed children carrying the PON1 192R-allele had higher abdominal circumference, body fat content, BMI Z-scores, blood pressure, and serum concentrations of leptin and IGF-I at school age than unexposed children. The effects were related to the prenatal exposure level. For children with the PON1 192QQ genotype, none of the variables was affected by prenatal pesticide exposure. Conclusion Our results indicate a gene-environment interaction between prenatal pesticide exposure and the PON1 gene. Only exposed children with the R-allele developed adverse cardiovascular risk profiles thought to be associated with the R-allele.
Lower birth weight and increased body fat at school age in children prenatally exposed to modern pesticides: a prospective study
Christine Wohlfahrt-Veje, Katharina M Main, Ida M Schmidt, Malene Boas, Tina K Jensen, Philippe Grandjean, Niels E Skakkeb?k, Helle R Andersen
Environmental Health , 2011, DOI: 10.1186/1476-069x-10-79
Abstract: In a prospective study of 247 children born by women working in greenhouses in early pregnancy, 168 were categorized as prenatally exposed to pesticides. At three months (n = 203) and at 6 to11 years of age (n = 177) the children underwent a clinical examination and blood sampling for analysis of IGF-I, IGFBP3 and thyroid hormones. Body fat percentage at age 6 to11 years was calculated from skin fold measurements. Pesticide related associations were tested by linear multiple regression analysis, adjusting for relevant confounders.Compared to unexposed children birth weight and weight for gestational age were lower in the highly exposed children: -173 g (-322; -23), -4.8% (-9.0; -0.7) and medium exposed children: -139 g (-272; -6), -3.6% (-7.2; -0.0). Exposed (medium and highly together) children had significantly larger increase in BMI Z-score (0.55 SD (95% CI: 0.1; 1.0) from birth to school age) and highly exposed children had 15.8% (0.2; 34.6) larger skin folds and higher body fat percentage compared to unexposed. If prenatally exposed to both pesticides and maternal smoking (any amount), the sum of four skin folds was 46.9% (95% CI: 8.1; 99.5) and body fat percentage 29.1% (95% CI: 3.0; 61.4) higher. There were subtle associations between exposure and TSH Z-score -0.66(-1.287; -0.022) and IGF-I Z-score (girls: -0.62(-1.0; -0.22), boys: 0.38(-0.03; 0.79)), but not IGFBP3.Occupational exposure to currently used pesticides may have adverse effects in spite of the added protection offered to pregnant women. Maternal exposure to combinations of modern, non-persistent pesticides during early pregnancy was associated with affected growth, both prenatally and postnatally. We found a biphasic association with lower weight at birth followed by increased body fat accumulation from birth to school age. We cannot rule out some residual confounding due to differences in social class, although this was adjusted for. Associations were stronger in highly exposed than in medium ex
Anti-Müllerian Hormone and Its Clinical Use in Pediatrics with Special Emphasis on Disorders of Sex Development
Marie Lindhardt Johansen,Casper P. Hagen,Trine Holm Johannsen,Katharina M. Main,Jean-Yves Picard,Anne J?rgensen,Ewa Rajpert-De Meyts,Anders Juul
International Journal of Endocrinology , 2013, DOI: 10.1155/2013/198698
Abstract: Using measurements of circulating anti-Müllerian hormone (AMH) in diagnosing and managing reproductive disorders in pediatric patients requires thorough knowledge on normative values according to age and gender. We provide age- and sex-specific reference ranges for the Immunotech assay and conversion factors for the DSL and Generation II assays. With this tool in hand, the pediatrician can use serum concentrations of AMH when determining the presence of testicular tissue in patients with bilaterally absent testes or more severe Disorders of Sex Development (DSD). Furthermore, AMH can be used as a marker of premature ovarian insufficiency (POI) in both Turner Syndrome patients and in girls with cancer after treatment with alkylating gonadotoxic agents. Lastly, its usefulness has been proposed in the diagnosis of polycystic ovarian syndrome (PCOS) and ovarian granulosa cell tumors and in the evaluation of patients with hypogonadotropic hypogonadism. 1. Introduction Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance, is essential for the involution of the Müllerian ducts (the anlagen of the internal female genitalia) in the male fetus [1–3]. Male sex differentiation is completely dependent on the normal development of testes that produce ample amounts of testosterone and AMH. The two hormones, produced by Leydig cells and Sertoli cells, respectively, represent two distinct pathways in male sex differentiation. Testosterone is responsible for the differentiation of the Wolffian ducts, the urogenital sinus, and the external genitalia. By contrast, AMH does not have any known function in female fetal organogenesis. Determination of the serum AMH concentration is used in various ways in clinical pediatrics to determine the presence of testicular tissue in patients with cryptorchidism, suspected anorchia, or more severe Disorders of Sex Development (DSD). Also, AMH may be used as a marker of premature ovarian insufficiency (POI). It has been proposed as a marker in polycystic ovarian syndrome (PCOS) [4], as a tumor load marker in ovarian granulosa cell tumors [5] and, lastly, in hypogonadotropic hypogonadism [6]. This paper gives a brief overview of the physiology of AMH and seeks to give clinicians a tool when interpreting results from different assays. The aim is to simplify the use of AMH in clinical pediatrics. 2. Expression and Regulation of AMH AMH is produced by Sertoli and granulosa cells in the male and female, respectively. AMH is a member of the TGF- family and is encoded by the AMH gene, which contains 5 exons [7] and is
A Wiener-Laguerre Model of VIV Forces Given Recent Cylinder Velocities
Philippe Main on
Mathematical Problems in Engineering , 2011, DOI: 10.1155/2011/414702
Abstract: Slender structures immersed in a cross flow can experience vibrations induced by vortex shedding (VIV), which cause fatigue damage and other problems. VIV models that are used in structural design today tend to assume harmonic oscillations in some way or other. A time domain model would allow to capture the chaotic nature of VIV and to model interactions with other loads and nonlinearities. Such a model was developed in the present work: for each cross section, recent velocity history is compressed using Laguerre polynomials. The compressed information is used to enter an interpolation function to predict the instantaneous force, allowing to step the dynamic analysis. An offshore riser was modeled in this way: some analyses provided an unusually fine level of realism, while in other analyses, the riser fell into an unphysical pattern of vibration. It is concluded that the concept is promising, yet that more work is needed to understand orbit stability and related issues, in order to produce an engineering tool.
Page 1 /1201
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.