Bulgarian Academy of Sciences

About: Bulgarian Academy of Sciences is a government organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Coupling constant & Catalysis. The organization has 17989 authors who have published 36276 publications receiving 642820 citations. The organization is also known as: Bulgarian Academy of Sciences，簡稱：BAS & Balgarska Akademiya na Naukite.

Direct thiazolidinedione action in the human ovary: insulin-independent and insulin-sensitizing effects on steroidogenesis and insulin-like growth factor binding protein-1 production.

Abstract: ContextandObjective:Hyperinsulinemiacontributestothepathogenesis of ovarian dysfunction in insulin-resistant states, including polycystic ovary syndrome (PCOS). Peroxisome proliferator activated receptor- (PPAR-) agonists [thiazolidinediones (TZDs)] ameliorate hyperandrogenism in polycystic ovary syndrome presumably because they reduce systemic hyperinsulinemia. Direct effects of TZDs in the ovary, however, cannot be excluded. We explored direct effects of TZDs in cultured human ovarian cells. Methods: Human ovarian cells, obtained from oophorectomy specimens, were cultured in the presence or absence of rosiglitazone or pioglitazone, insulin, and gonadotropins. Steroid hormone and IGFbinding protein-1 (IGFBP-1) concentrations were measured in conditioned tissue culture medium. Results: Rosiglitazone or pioglitazone stimulated progesterone production up to 156% (P 0.001) and 131% (P 0.001) of baseline, respectively. Pioglitazone but not rosiglitazone, inhibited baseline andFSH-stimulatedestradiolproductionby20%(P0.001)and50% (P 0.001), respectively. Both rosiglitazone and pioglitazone abolished insulin-dependent stimulation of estradiol production in the presence of FSH. Rosiglitazone and pioglitazone inhibited testosterone production by 10% (P 0.012) and 15% (P 0.023), respectively, andabolishedinsulin-inducedstimulationoftestosteroneproduction. In the absence of insulin, pioglitazone or rosiglitazone stimulated IGFBP-1 production up to 160% (P 0.001) and 125% (P 0.036) of baseline, respectively. Pioglitazone and rosiglitazone enhanced insulin-induced inhibition of IGFBP-1 production by 13% and 20%, respectively (P 0.001). Conclusions: PPAR- agonists directly stimulate progesterone and IGFBP-1 production, inhibit estradiol and testosterone production, abolish insulin-induced stimulation of testosterone production and insulin-dependent stimulation of estradiol production in the presence of FSH, and enhance insulin-induced inhibition of IGFBP-1 production in human ovarian cells. PPAR- represents a novel system of ovarian regulation. (J Clin Endocrinol Metab 90: 6099–6105, 2005)

Factors Controlling Naphthenic Acid Corrosion

Abstract: A laboratory study was conducted to elucidate the influence of chemical and physical parameters on corrosion of type 1018 carbon steel (CS, UNS G10180)and 5% Cr-0.5% Mo steel in oils conta...

Sleep patterns in children with attention-deficit/hyperactivity disorder, tic disorder, and comorbidity.

Abstract: Background: In children, attention-deficit/hyperactivity disorder (ADHD), tic disorder (TD), and their coexistence (ADHD + TD comorbidity) are very common and clinically important. Associated sleep patterns and their clinical role are still insufficiently investigated. This study aimed at characterizing these sleep patterns in children with ADHD, TD, and ADHD + TD comorbidity and determining whether, in ADHD + TD, the factors ADHD and TD may affect the sleep pattern in an independent (additive) or in a complex (interactive) manner. Method: By means of polysomnography, sleep patterns were investigated in 4 groups of unmedicated 8.0‐16.4-year-old children (healthy controls, ADHD-only, TD-only, and ADHD + TD). Each group consisted of 18 subjects matched for age, gender, and intelligence. Results: ADHD was primarily characterized by increase in rapid eye movement (REM) sleep, whereas TD patients displayed lower sleep efficiency and elevated arousal index in sleep. In children with ADHD + TD, both effects appeared. No interaction between the ADHD and TD factors was found for any of the sleep parameters. Significant correlations between sleep patterns and clinical symptoms were found. Conclusions: ADHD and TD are characterized by specific sleep alterations. When coexisting, the two disorders alter the sleep pattern in an additive manner, suggesting a high impact on clinical and therapeuticperspectives. Keywords: Attention-deficit/hyperactivitydisorder,ticdisorder,comorbidity, sleep, children.

Kβ mainline X-ray emission spectroscopy as an experimental probe of metal-ligand covalency.

Abstract: The mainline feature in metal Kβ X-ray emission spectroscopy (XES) has long been recognized as an experimental marker for the spin state of the metal center. However, even within a series of metal compounds with the same nominal oxidation and spin state, significant changes are observed that cannot be explained on the basis of overall spin. In this work, the origin of these effects is explored, both experimentally and theoretically, in order to develop the chemical information content of Kβ mainline XES. Ligand field expressions are derived that describe the behavior of Kβ mainlines for first row transition metals with any dn count, allowing for a detailed analysis of the factors governing mainline shape. Further, due to limitations associated with existing computational approaches, we have developed a new methodology for calculating Kβ mainlines using restricted active space configuration interaction (RAS–CI) calculations. This approach eliminates the need for empirical parameters and provides a powerful...