The present study aimed to examine the effect of melatonin on naloxone-induced luteinizing hormone (LH) secretion in ovariectomized estrogen-primed rats. A single intracerebroventricular (i.c.v.) injection of naloxone (mu opioid receptor blocker, 15 micrograms) or an intravenous (i.v.) injection of LH-releasing hormone (LHRH, 50 ng/kg) elicited a transient and significant increase in the serum LH concentration within 10 min. While an i.c.v. injection of 100 ng melatonin by itself did not change the basal LH release, it almost completely inhibited the naloxone-induced LH release. Melatonin (10 ng) also significantly reduced the effect of naloxone. However, an i.c.v. injection of 100 ng melatonin did not affect the LHRH-induced LH release. In separate experiments, the effect of melatonin on naloxone-induced pulsatile LH secretion was studied in estrogen-treated rats. A continuous i.v. infusion of naloxone (20 mg/kg/h) induced LH pulses in rats treated i.c.v. with saline. An i.c.v. administration of 100 ng melatonin, which by itself did not affect basal LH secretion, significantly reduced the frequency, but not the amplitude, of LH pulses induced by the naloxone infusion. These results show that melatonin has a suprapituitary site of action to inhibit naloxone-induced LH release, and suggest that melatonin has an effect in inhibiting the activity of the hypothalamic LHRH pulse generator, either directly or indirectly, in female rats. 相似文献
The hydrolysis of glucosidic linkage catalyzed by every carbohydrate-hydrolase is a reaction in which the product retains (alpha-->alpha or beta-->beta) or inverts (alpha-->beta or beta-->alpha) the anomeric configuration of the substrate. alpha-Glucosidase and glucoamylase are essentially distinguished by releasing alpha-glucose and beta-glucose, respectively, from the common substrates having alpha-glucosidic linkage. The distinction in the substrate specificities of the two enzymes was explained by the subsite affinities in their active sites. The amino acid sequences of the regions containing the catalytic sites were compared in alpha-glucosidases and glucoamylases from various sources. alpha-Glucosidases were suggested to be grouped into two families by their primary structures. The catalytic reaction mechanisms of carbohydrate-hydrolases were discussed in the two significant models of a nucleophilic displacement mechanism and an oxocarbenium ion intermediate mechanism. 相似文献
We report a 4-year-old boy with benign partial epilepsy (BPE) with affective symptoms associated with hyperkinetic behavior during interictal periods. He had had hypermobility and restlessness since about age 3. At 4 years, 6 months, he developed episodes consisting of an expression of terror without complete loss of consciousness. Although we first suspected an acute psychic problem, the ictal EEG was abnormal. After carbamazepine (CBZ) therapy, the frequency of the attacks decreased dramatically and the hyperkinetic behavior gradually diminished. 相似文献
Summary This paper presents two efficient algorithms for drawing plane graphs nicely. Both draw all edges of a graph as straight line segments without crossing lines. The first draws a plane graph convex if possible, that is, in a way that every inner face and the complement of the outer face are convex polygons. The second, using the first, produces a pleasing drawing of a given plane graph that satisfies the following property as far as possible: the complements of 3-connected components, together with inner faces and the complement of the outer face, are convex polygons. The running time and storage space of both algorithms are linear in the number of vertices of the graph. 相似文献
The efficiency of power dissipation (η) in a dynamic material model has been conventionally used for qualitative predictions to estimate the hot working conditions at which dynamic recrystallization (DRX) is dominant. However, predicting the quantitative value of the DRX fraction (XDRX) from η remains a challenge. In this paper, a constitutive equation is proposed to quantitatively predict XDRX using η. The proposed equation for describing XDRX is derived from the reaction rate equation using the assumption that the DRX rate depends on η. The proposed equation is verified via hot compression tests of equiaxed Ti–6Al–4V ELI alloys (Ti-64) in the (α + β) region. The predicted and experimental XDRX values are found to be generally consistent with one another, exhibiting an average absolute error of 0.05. Furthermore, the proposed equation provides the same level of prediction accuracy as the conventional Johnson–Mehl–Avrami–Kolmogorov (JMAK) equation. Therefore, the proposed equation can be used to quantitatively predict XDRX following hot compression tests of equiaxed Ti-64. Moreover, compared with the JMAK equation, the proposed equation is expressed in fewer parameters and constant terms. It is, thus, expected to facilitate the quantitative prediction of XDRX.
For the purpose of synthesizing standards to be used in the quantification of TAG hydroperoxides, three TAG (1,2-dioleoyl-3-palmitoylglycerol,
1-oleoyl-2-linoleoyl-3-palmitoylglycerol, and triolein) monohydroperoxides were chemically synthesized as authentic specimens.
TAG were prepared by using a simple condensation in pyridine of glycerol and the corresponding acid chlorides. These TAG were
then converted into monohydroperoxides by a photosensitized peroxidation. The synthesized monohydroperoxides were analyzed
by normal-phase and RP-HPLC. The results of normal-phase HPLC analysis showed that monohydroperoxides from a corresponding
TAG were a mixture of regioisomers. In RP-HPLC, however, the regioisomers of monohydroperoxides were not separated and gave
a single peak, which may improve the sensitivity for the detection of TAG monohydroperoxides. In this study TAG monohydroperoxide
standards were synthesized; these will be useful for the study of yet unknown biological and pathological roles of TAG hydroperoxides. 相似文献
Very large macrophages, which we have termed "giant macrophages" (G-M phi), have been found in renal tubules, some containing cytoplasmic vacuoles. To elucidate their pathophysiological roles, we examined renal biopsy tissues from various primary glomerulonephritis (GN) and tubulointerstitial nephritis (TIN) using immunohistochemistry with monoclonal antibodies against M phi and other cell surface markers. Giant macrophages were absent or rare in TIN, minimal change nephrotic syndrome, and minor glomerular abnormalities, but G-M phi was plentiful in progressive glomerulonephrides such as IgA nephropathy with crescents, membranoproliferative GN, focal segmental glomerulosclerosis, and especially in crescentic GN. These G-M phi were usually seen in the lumen of renal tubules, but occasionally were found in the Bowman's spaces and glomerular tufts, and similar cells were also found in urine. Moreover, they frequently made contact with tubular epithelial cells expressing intercellular adhesion molecule-1, and the tubular epithelial cells in such lesions often had degenerative changes. Giant M phi may damage tubular epithelial cells from the luminal side. Phenotypically, G-M phi showed activated (CD71+) and mature (25F9+) characteristics along with features of M phi (CD68+), and the cytoplasm contained a great deal of lipids. The numbers of G-M phi in renal tissues closely correlated with the degree of hematuria (rho = 0.5, P < 0.001), serum creatinine value (r = 0.63, P < 0.001) in GN patients (N = 96) and with proteinuria in IgA nephropathy patients (r = 0.89, P < 0.001, N = 27). These data suggest that G-M phi are M phi that were activated and matured in certain active inflammatory sites, which flowed into tubules and then into urine. Thus, the existence of G-M phi in biopsy tissue or urine reflect the activity of GN and may have a predictive value for the progression of GN. 相似文献