22 research outputs found

    On baier's sort of maximal Lyndon substrings

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    We describe and analyze in terms of Lyndon words an elementary sort of maximal Lyndon factors of a string and prove formally its correctness. Since the sort is based on the first phase of Baier’s algorithm for sorting of the suffixes of a string, we refer to it as Baier’s sort

    A Novel Reconfigurable Filter Using Periodic Structures

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    Abstract- In this paper, a reconfigurable filter is realized using electromagnetic bandgap structures (EBG) which can be switched from bandpass to bandstop filter at the same frequency by PIN diodes. A unit model for the reconfigurable filter is derived by equivalent circuit approach and full wave electromagnetic simulation is used for extracting the values of the lumped elements. The extracted parameters show that the bandpass and bandgap effect of the EBG cells. The dispersion diagram is obtained for the structure by combining the commercial software and the Floquet's theorem. The PIN diodes are used to switch from bandpass to bandstop filter. The measurement results show that the insertion loss in bandpass filter is around 2.1 dB and the 3-dB bandwidth is around 5.2 GHz which is suitable for wideband applications. For the bandstop filter, the 20 dB rejection bandwidth is 5.3 GHz and the insertion loss in the pass band is 1.6 dB

    Gel beads from novel ionic polysaccharides

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    Stable gelling systems were obtained by mixing polyanion solutions with solutions containing suitable polycations. Carboxymethyl cellulose was chosen as the polyanion, whilst a number of polycations, with different molecular weights and charge densities, were tested. In particular, both low molecular weight polyamines and new synthetically aminated polysaccharides, derived from pullulan and scleroglucan, were used. Stable gels, in the absence of phase separation, were obtained only with flexible polycationic species. The morphological characterisation of the gel beads obtained were studied by scanning electron microscopy and NMR microscopy

    Isolation of a sulfobromophthalein binding protein from hepatocyte plasma membrane

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    This paper deals with the isolation and partial characterization of a protein capable of high affinity sulfobromophthalein-binding from liver plasma membrane. The purification involves acetone powder of a crude preparation of rat liver plasma membrane, salt extraction and purification through two chromatographic steps. Based on sulfobromophthalein binding, the process gives a yield of approximately 40%, with a purification of about 300 times with respect to the starting homogenate. The best preparation can bind more than 100 nmol sulfobromophthalein/mg protein. The protein behaves as a single species in dodecyl sulphate polyacrylamide gel electrophoresis, with an apparent molecular weight of 1.7 \ub7 105. The molecule does not contain sugars. The dissociation constant of the protein \ub7 sulfobromophthalein complex has been found to be 4 \ub7 10 126 M, a value in agreement with that of high affinity binding sites described on isolated liver plasma membrane

    Conjugated equine estrogens, estrone sulphate and estradiol valerate oral administration in ovariectomized rats: effects on central and peripheral allopregnanolone and beta-endorphin.

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    OBJECTIVES: Several natural or synthetic estrogenic molecules are commonly used in oral hormone replacement therapy for the relief of menopausal complaints and for the primary prevention of cardiovascular disease and osteoporosis. Little information is available concerning the comparative efficacy of different compounds on neuroendocrine function. The opioid peptide beta-endorphin (beta-EP), and the neurosteroid allopregnanolone are considered markers of neuroendocrine function and their synthesis and action is regulated by gonadal steroids. The present study aimed to investigate the effects of a 2-week oral treatment with estradiol valerate (EV), estrone sulphate (ES), or conjugated equine estrogen (CEE) on central and peripheral beta-EP and allopregnanolone levels in ovariectomized (OVX) female rats. METHODS: Twelve groups of Wistar OVX rats received oral EV (0.05, 0.1, 0.5 and 1 mg/Kg/day) or ES (0.1, 0.5, 1 and 2 mg/Kg/day), or CEE (0.1, 0.5, 1 and 2 mg/Kg/day) for 14 days. One group of fertile and one group of OVX rats were used as controls. beta-EP content was assessed in hypothalamus, hippocampus, anterior and neurointermediate pituitary, and plasma, while allopregnanolone content was assessed in hypothalamus, hippocampus, anterior pituitary, adrenals and serum. RESULTS: Ovariectomy induced a significant decrease in beta-EP and allopregnanolone content in hypothalamus, hippocampus, pituitary, and serum, while it increased allopregnanolone content in the adrenals. In OVX rats, the administration of each molecule reversed the ovariectomy-induced beta-EP and allopregnanolone changes in a dose-dependent fashion, therefore completely restoring their concentration. At higher doses, the estrogenic compounds induced significantly higher levels of allopregnanolone and beta-EP than in fertile rats. CEE induced higher allopregnanolone levels in hypothalamus, anterior pituitary and serum than the other estrogenic molecules, and in the hippocampus with respect to EV alone. CEE produced higher beta-EP levels in the hippocampus and hypothalamus with respect to EV and ES. CONCLUSION: In the examined tissue and serum estrogens restore the ovariectomy induced changes in allopregnanolone and beta-EP content in a dose-dependent manner; the magnitude of these effects is not uniform and it is related to the different tissues and the employed compounds

    Adrenal response to adrenocorticotropic hormone stimulation in patients with premenstrual syndrome

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    Several studies have been performed during recent years to investigate the existence of a possible endocrine cause for premenstrual syndrome (PMS); the results reported are often discordant. Great interest has been raised around allopregnanolone, which could be involved in the determination of mood disorders reported by PMS patients. During the luteal phase, lower levels of this hormone have been detected in PMS patients. The aim of our study was to evaluate estradiol, progesterone, dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), androstenedione, total and free testosterone, cortisol, pregnenolone and allopregnanolone levels in 20 patients suffering from PMS and to compare them with those found in 20 fertile healthy women in the follicular and the luteal phases. Adrenocorticotropic hormone (ACTH) tests after dexamethasone suppression were performed in 10 patients of each group during the follicular and the luteal phases. In the PMS group, significantly lower allopregnolone levels were found in the luteal phase, while progesterone was lower in the PMS group in both phases. In the PMS group, higher free testosterone levels were found during the luteal phase and higher DHEA levels in both the follicular and the luteal phases. The present data confirm reduced allopregnanolone levels in the luteal phase in PMS patients, together with higher levels of DHEA and free testosterone. It is possible to conclude that, in addition to the previously described reduced luteal secretion of allopregnanolone, the adrenal gland production of this steroid in PMS sufferers is also impaired in the luteal phase. Considering the specific actions of these hormones on the control of mood and behavior, this specific hormonal milieu may contribute to the cyclic occurrence of anxiety, aggressiveness and irritability reported by PMS patients
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