Electronic Library of Scientific Literature - © Academic Electronic Press


Volume 36 / No. 2 / 2002



Ioannis Ilias, Alexandros N Vgontzas, Astero Provata, George Mastorakos

Endocrine Unit, «Evgenidion» Hospital, University of Athens, Athens, Greece;
Sleep Research and Treatment Center, Department of Psychiatry, College of Medicine, Pennsylvania State University, Hershey Pennsylvania, USA;
Institute of Physical Chemistry, National Research Center «Demokritos», Athens, Greece
E-mail: lliaslo@mail.nih.gov

Objective. The circadian secretory profiles of cortisol and growth hormone (hGH) in normal subjects are interrelated. Slight alterations in cortisol secretion are paralleled by similar ones of hGH secretion. Under physiological conditions an inhibitory effect of glucocorticoids on hGH secretion is more potent than a stimulatory one, while in normal young subjects the nychtohemeral cortisol and hGH levels are lower and higher, respectively, post 24 hours total sleep-deprivation, compared to baseline values. The aim of the present work was to further assess the qualitative characteristics of the 24-hour secretory patterns of these two hormones before and after 24 hours total sleep deprivation, by studying their non-linear profiles using fractal analysis.
Methods. Cortisol and hGH were measured in 24-hour samples drawn from 10 healthy men (mean age±SD: 24±1 yr, mean BMI±SD: 25±1 kg/m2) before and after 24 hours total sleep deprivation. Twenty-four hour blood sampling was performed serially every 30 min the day before and the day after total sleep deprivation. The 24-hour hormone profiles were analyzed by Fourier spectrum, in order to verify periodicities; the corresponding attractors were drawn and their respective fractal dimensions were calculated using the box counting method.
Results. Diurnal cortisol levels before sleep deprivation gave rise to a fractal attractor with a D0 fractal dimension of 2.65±0.03, which decreased, post-sleep deprivation, to D0: 2.18±0.04. Growth hormone before sleep deprivation gave rise to a fractal attractor with a D0 dimension of 1.96±0.60, which increased to 2.24±0.60 post-sleep deprivation. These post-sleep deprivation changes of the fractal dimensions of cortisol and hGH, suggest that sleep deprivation leads to a more regular secretory profile of cortisol, while it tends to render hGH secretory profile less regular. Additionally, these changes of the fractal dimensions parallell the previously described quantitative overall changes of these hormones.
Conclusions. The post-sleep deprivation decrease of cortisol fluctuation might reflect the mechanism by which sleep deprivation temporarily improves mood in melancholic depression, a condition associated with hyperactivity of the hypothalamic-pituitary-adrenal axis.
Key words: Cortisol – growth hormone – human – sleep deprivation – non-linear analysis

ENDOCRINE REGULATIONS, Vol. 36, 63–72, 2002

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Zofia Cervenakova, Lucia Ksinantova, Juraj Koska

Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
E-mail: ueencerv@savba.sk

Objective. Several indices have been published to quantify insulin sensitivity from fasting plasma glucose and fasting plasma insulin levels as well as from the data obtained by the oral glucose tolerance test (oGTT). Obesity represents the main risk factor associated with development of insulin resistance and Type 2 diabetes mellitus. The aim of this study was to evaluate the influence of body composition on various indices of insulin sensitivity and secretion in subjects with normal glucose tolerance.
Methods. A total of 33 male subjects (aged 26-51 years, BMI 19.7-30.9 kg/m2) underwent a standard oral glucose tolerance test (oGTT). Thereafter the cut-off value of BMI= 25 kg/m2 was set to divide the group into normal subjects and subjects with overweight. Indices of insulin sensitivity and secretion were calculated from plasma glucose and insulin concentrations using the formulas proposed by Matthews et al. (1985), Cederholm and Wibell (1990), Matsuda and DeFronzo (1999) and Stumvoll et al. (2000).
Results. All subjects had a normal glucose tolerance according to standard diagnostic criteria. No difference was found in the course of glycemia, while overweight subjects displayed an enhanced insulin response (P<0.01). BMI correlated closely with all indices. The correlation coefficient was highest in ISIMatsuda, followed by ISICederholm and ISIStumvoll. The indices of insulin sensitivity all significantly increased in the overweight group. The groups did not differ in the values of index SecrHOMA.
Conclusions. The easiest way to predict the insulin sensitivity and to control the development of insulin resistance in a subject with yet normal glucose tolerance, but at high risk of development of overt Type 2 diabetes is to calculate an index from glucose and insulin concentrations during an oGTT. However, the assessment of appropriate cut-off values is necessary for introducing the indices in clinical practice.
Key words: Glucose – Insulin – Diabetes – Insulin resistance

ENDOCRINE REGULATIONS, Vol. 36, 73–77, 2002

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Michal Pohanka, Richard Hampl, Ivan Šterzl, Luboslav Stárka

Institute of Endocrinology, Národní 8, 116 94 Praha 1, Czech Republic
E-mail: rhampl@endo.cz

Objective. In addition to many components, seminal fluid contains also hormonal steroids. So far, the studies were focused mostly to androgens, their precursors, estrogens and also cortisol, in most instances in relation to sperm abnormalities. Our group detected for the first time in the ejaculate 7-hydroxylated metabolites of dehydroepiandrosterone, believed to function as immunomodulatory and immunoprotective agents. Occurrence of steroids in seminal fluid and their possible role is reviewed in the first part of the article.
Methods. In a group of 34 men (age 21-46 years) with various problems of fertility the presence of 7-hydroxydehydroepiandrosterone isomers and dehydroepiandrosterone in seminal fluid was found.. The concentrations of steroids in seminal fluid and plasma were determined by recently developed radioimmunoassay. In brief, the ejaculate was extracted twice with diethyl ether and the water phase was separated by freezing in solid carbon dioxide and evaporating the solvent to dryness. The dry residue was dissolved in methanol:water:light petroleum ether (1.3:1.0:0.3 ml) and mixed. After separation the water-methanolic phase was evaporated, the dry residue was re-dissolved in phosphate buffer and aliquots were used for RIA. The results were corrected for losses by counting the residual radioactivity of [3H] testosterone added initially to the sample of seminal fluid.
Results. The concentrations of 7-hydroxydehydroepiandrosterone varied from 1.08 to as much as 15.7 nmol/l, while those of dehydroepiandrosterone were about five times higher. The concentrations of both 7-hydroxydehydroepiandrosterone isomers were close to or even higher than recently reported levels of these substances in blood serum.
Conclusion. The presence of steroids derived from dehydroepiandrosterone by 7-hydroxylation with recently reported immunomodulatory activity was for the first time demonstrated in seminal fluid of normal men.
Key words:
Seminal fluid – Steroid hormones – 7-Hydroxydehydroepiandrosterone – Dehydroepiandrosterone –Immunomodulatory activity

ENDOCRINE REGULATIONS, Vol. 36, 79–86, 2002

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Maria Fickova

Institute of Experimental Endocrinology, Slovak Academy of Sciences, 833 06 Bratislava, Slovakia
E-mail: ueenfick@savba.sk

Key words: EGF receptor – structure – activation

ENDOCRINE REGULATIONS, Vol. 36, 87–93, 2002

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Richard Imrich

Institute of Experimental Endocrinology, Slovak Academy of Sciences, Vlarska 3, 833 06 Bratislava, Slovak Republic
E-mail: ueenmri@savba.sk

Interactions between the neuroendocrine and immune system play an important role in maintaining and restoring homeostasis. In susceptible individuals a dysfunction of the neuroendocrine system may be one of the risk factors involved in the pathogenesis of rheumatic diseases. Specific causes of altered neuroendocrine function are still not fully elucidated. Accumulation of genetical, environmental, behavioral and other risk factors during long preclinical period may result in chronic imbalances in homeostatic mechanisms maintained by neuroendocrine, microvascular and immune systems. Chronic inflammatory stress mediated by humoral and neural signals during active stages of the disease and autoantibodies against the structures of the neuroendocrine system may further participate in the neuroendocrine dysfunction. In a subset of patients with rheumatoid arthritis (RA), an assumed defect of the hypothalamic-pituitary-adrenocortical axis may be implicated in the pathogenesis. Results of some studies support the concept of adrenal dysfunction in women with premenopausal onset of the RA. Significantly lower levels of dehydroepiandrosterone sulfate (DHEAS) plasma levels of women who subsequently developed RA indicate that neuroendocrine dysfunction may be present already in preclinical period and thus are not only secondary due to ongoing inflammatory process. These findings are sketching the new prospects of possible primary prevention of RA in the future. The role of some other hormones including prolactin, growth hormone, sex hormones and involvement of autonomic nervous system in relation with the rheumatic diseases is also reviewed in the paper. Further research concerning their role in the pathogenesis of other rheumatic diseases will possibly provide new prospects in optimizing their therapy.
Keywords: Rheumatoid arthritis – Systemic lupus erythematosus – Sjoegren’s syndrome – HPA axis – Prolactin – Growth hormone – Autonomic nervous system – HPG axis

ENDOCRINE REGULATIONS, Vol. 36, 95–106, 2002

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