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Sample records for acrosome reaction mediated

  1. Delineation of downstream signalling components during acrosome reaction mediated by heat solubilized human zona pellucida

    Directory of Open Access Journals (Sweden)

    Talwar Pankaj

    2010-01-01

    Full Text Available Abstract Background Human egg is enveloped by a glycoproteinaceous matrix, zona pellucida (ZP, responsible for binding of the human spermatozoa to the egg and induction of acrosomal exocytosis in the spermatozoon bound to ZP. In the present manuscript, attempts have been made to delineate the downstream signalling components employed by human ZP to induce acrosome reaction. Methods Heat-solubilized human ZP (SIZP was used to study the induction of acrosome reaction in capacitated human spermatozoa using tetramethylrhodamine isothiocyanate conjugated Pisum sativum agglutinin (TRITC-PSA in absence or presence of various pharmacological inhibitors. In addition, intracellular calcium ([Ca2+]i levels in sperm using Fluo-3 acetoxymethyl ester as fluorescent probe were also estimated in response to SIZP. Results SIZP induces acrosomal exocytosis in capacitated human sperm in a dose dependent manner accompanied by an increase in [Ca2+]i. Human SIZP mediated induction of acrosome reaction depends on extracellular Ca2+ and involves activation of Gi protein-coupled receptor, tyrosine kinase, protein kinases A & C and phosphoinositide 3 (PI3- kinase. In addition, T-type voltage operated calcium channels and GABA-A receptor associated chloride (Cl- channels play an important role in SIZP mediated induction of acrosome reaction. Conclusions Results described in the present study provide a comprehensive account of the various downstream signalling components associated with human ZP mediated acrosome reaction.

  2. The human acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    H.W.G.Baker; D.Y.Liu; C.Garrett; M.Martic

    2000-01-01

    We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, spermzona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization (IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one woman affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pellucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morphology. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion of acrosome intact sperm in the insemination medium was related to the IVF rate. Inducing the acrosome reaction with a calcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented spermzona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding. Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normal sperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrated the zona. In contrast, fertilization and pregnancy rates were high with intracytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signal transduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler tests and treatments for the patients and also provide new leads for contraceptive development.

  3. Carbohydrates mediate sperm-ovum adhesion and triggering of the acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    DaulatR.P.Tulsiani

    2000-01-01

    The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of the opposite gametes. The male gamete undergoes continuous morphological and biochemical modifications during sperm development in the testis (spermatogenesis), maturation in the epididymis, and capacitation in the female reproductive tract. Only the capacitated spermatozoa are able to recognize and bind to the bioactive glycan residue(s) on the ovum's extracellular coat, the zona pellucida (ZP). Sperm-zona binding in the mouse and several other species is believed to take place in two stages. First, capacitated (acrosome-intact) spermatozoa loosely and reversibly adhere to the zona-intact ovum. In the second stage tight irreversible binding occurs. Both types of bindings are attributed to the presence of glycan- binding proteins (receptors) on the sperm plasma membrane and their complementary bioactive glycan units (ligands) on the surface of the ZP. The carbohydrate-mediated adhesion event initiates a signal transduction cascade resulting in the exocytosis of acrosomal contents. This step is believed to be prerequisite which allows the hypemctivated acrosome-reacted spermatozoa to penetrate the ZP and fertilize the ovum. This review focuses on the role of carbohydrate residues in sperm-ovum interaction, and triggering of the acrosome reaction. I have attempted to discuss extensive progress that has been made to enhance our understanding of the well programmed multiple molecular events necessary for successful fertilization. This review will identify these events, and discuss the functional significance of carbohydrates in these events.

  4. Zn2+-stimulation of sperm capacitation and of the acrosome reaction is mediated by EGFR activation.

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    Michailov, Yulia; Ickowicz, Debbi; Breitbart, Haim

    2014-12-15

    Extracellular zinc regulates cell proliferation via the MAP1 kinase pathway in several cell types, and has been shown to act as a signaling molecule. The testis contains a relatively high concentration of Zn(2+), required in both the early and late stages of spermatogenesis. Despite the clinical significance of this ion, its role in mature sperm cells is poorly understood. In this study, we characterized the role of Zn(2+) in sperm capacitation and in the acrosome reaction. Western blot analysis revealed the presence of ZnR of the GPR39 type in sperm cells. We previously demonstrated the presence of active epidermal growth factor receptor (EGFR) in sperm, its possible transactivation by direct activation of G-protein coupled receptor (GPCR), and its involvement in sperm capacitation and in the acrosome reaction (AR). We show here that Zn(2+) activates the EGFR during sperm capacitation, which is mediated by activation of trans-membrane adenylyl cyclase (tmAC), protein kinase A (PKA), and the tyrosine kinase, Src. Moreover, the addition of Zn(2+) to capacitated sperm caused further stimulation of EGFR and phosphatydil-inositol-3-kinase (PI3K) phosphorylation, leading to the AR. The stimulation of the AR by Zn(2+) also occurred in the absence of Ca(2+) in the incubation medium, and required the tmAC, indicating that Zn(2+) activates a GPCR. The AR stimulated by Zn(2+) is mediated by GPR39 receptor, PKA, Src and the EGFR, as well as the EGFR down-stream effectors PI3K, phospholipase C (PLC) and protein kinase C (PKC). These data support a role for extracellular zinc, acting through the ZnR, in regulating multiple signaling pathways in sperm capacitation and the acrosome reaction.

  5. Acrosome reaction: relevance of zona pellucida glycoproteins

    Institute of Scientific and Technical Information of China (English)

    Satish K Gupta; Beena Bhandari

    2011-01-01

    During mammalian fertilisation,the zona pellucida(ZP)matrix surrounding the oocyte is responsible for the binding of the spermatozoa to the oocyte and induction of the acrosome reaction(AR)in the ZP-bound spermatozoon.The AR is crucial for the penetration of the ZP matrix by spermatozoa.The ZP matrix in mice is composed of three glycoproteins designated ZP1,ZP2 and ZP3,whereas in humans,it is composed of four(ZP1,ZP2,ZP3 and ZP4).ZP3 acts as the putative primary sperm receptor and is responsible for AR induction in mice,whereas in humans(in addition to ZP3),ZP1 and ZP4 also induce the AR.The ability of ZP3 to induce the AR resides in its C-terminal fragment.O-linked glycans are critical for the murine ZP3-mediated AR.However,N-linked glycans of human ZP1,ZP3 and ZP4 have important roles in the induction of the AR.Studies with pharmacological inhibitors showed that the ZP3-induced AR involves the activation of the G1-coupled receptor pathway,whereas ZP1-and ZP4-mediated ARs are independent of this pathway.The ZP3-induced AR involves the activation of T-type voltage-operated calcium channels(VOCCs),whereas ZP1-and ZP4-induced ARs involve both T-and L-type VOCCs.To conclude,in mice,ZP3 is primarily responsible for the binding of capacitated spermatozoa to the ZP matrix and induction of the AR,whereas in humans(in addition to ZP3),ZP1 and ZP4 also participate in these stages of fertilisation.

  6. Equatorin is not essential for acrosome biogenesis but is required for the acrosome reaction

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Jianxiu [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Chen, Min [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China); Ji, Shaoyang; Wang, Xiaona; Wang, Yanbo [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Huang, Xingxu [MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University, Nanjing Biomedical Research Institute, National Resource Center for Mutant Mice, Nanjing 210061 (China); Yang, Lin; Wang, Yaqing [State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101 (China); Cui, Xiuhong; Lv, Limin [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China); Liu, Yixun, E-mail: liuyx@ioz.ac.cn [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China); Gao, Fei, E-mail: gaof@ioz.ac.cn [State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101 (China)

    2014-02-21

    Highlights: • Eqtn knockout mice were used for these experiments. • In vivo and in vitro fertilization analyses were performed. • Eqtn-deficient sperm were evaluated by transmission electron microscopy (TEM) and an A23187-induced acrosome reaction (AR) assay. • Co-immunoprecipitation (Co-IP) was performed to assess the interaction between Eqtn and the SNARE complex. - Abstract: The acrosome is a specialized organelle that covers the anterior part of the sperm nucleus and plays an essential role in mammalian fertilization. However, the regulatory mechanisms controlling acrosome biogenesis and acrosome exocytosis during fertilization are largely unknown. Equatorin (Eqtn) is a membrane protein that is specifically localized to the acrosomal membrane. In the present study, the physiological functions of Eqtn were investigated using a gene knockout mouse model. We found that Eqtn{sup −/−} males were subfertile. Only approximately 50% of plugged females were pregnant after mating with Eqtn{sup −/−} males, whereas more than 90% of plugged females were pregnant after mating with control males. Sperm and acrosomes from Eqtn{sup −/−} mice presented normal motility and morphology. However, the fertilization and induced acrosome exocytosis rates of Eqtn-deficient sperm were dramatically reduced. Further studies revealed that the Eqtn protein might interact with Syntaxin1a and SNAP25, but loss of Eqtn did not affect the protein levels of these genes. Therefore, our study demonstrates that Eqtn is not essential for acrosome biogenesis but is required for the acrosome reaction. Eqtn is involved in the fusion of the outer acrosomal membrane and the sperm plasma membrane during the acrosome reaction, most likely via an interaction with the SNARE complex.

  7. Study on the Vesiculation during Mouse Sperm Acrosome Reaction

    Institute of Scientific and Technical Information of China (English)

    林家豪; 周作民; 胡志刚; 王黎熔; 林敏; 张适

    1994-01-01

    The location of the mono-membrane and the bi-membrane vesicles of mouse sperm was identified using Con A in conjugation with the colloidal gold. The observation showed that both mono-membrane vesicfes and outer layer of the hi-membrane vesicles come from the outer acrosome membrane. The inner membrane layer of the bi-member vesicles and residual membrane distributed among the vesicles are really the ptasmatemma. It is suggested that the outer acrosome membrane did not fuse with the pfasmafemma during mouse sperm acrosome reaction and that both the mono-membrane and the bi-membrane vesicles of mouse sperm were formed due to winding of the outer acrosome membrane.

  8. Changes in the distribution and molecular mass of boar sperm acrosome-associated 1 proteins during the acrosome reaction; their validity as indicators for occurrence of the true acrosome reaction.

    Science.gov (United States)

    Ogura, Yukari; Takagishi, Yuki; Harayama, Hiroshi

    2016-09-01

    The aims of this study were to investigate changes in the distribution and molecular mass of boar sperm acrosome-associated 1 (SPACA1) proteins during the acrosome reaction and to discuss validity of SPACA1 proteins as indicators for occurrence of the true acrosome reaction. Boar ejaculated spermatozoa were used for induction of the extracellular Ca(2+)-dependent acrosome reaction (true acrosome reaction) or acrosomal damages (false acrosome reaction) and then subjected to double staining with the anti-SPACA1 protein antibody and FITC-PNA and Western blotting. Extracellular Ca(2+)-dependently acrosome-reacted spermatozoa were characterized by appearance of SPACA1 proteins in the postacrosomal region (; these spermatozoa were classified into SP-3&AR pattern of double staining). However, SPACA1 proteins were not observed in the postacrosomal region of frozen-thawed spermatozoa with severely damaged acrosomes (; these spermatozoa were classified into SP-2&AR pattern). Moreover, the spermatozoa in which acrosomes were severely damaged by incubation with cyclodextrins and without CaCl2 were classified into either SP-2&AR or SP-3&AR pattern. Although SPACA1 proteins were detected mainly as 36-42kDa proteins in the spermatozoa with intact acrosomes, small types of SPACA1 proteins (15-28kDa) increased in extracellular Ca(2+)-dependently acrosome-reacted spermatozoa as well as frozen-thawed spermatozoa with damaged acrosomes. These results show the increase of boar spermatozoa classified into SP-3&AR pattern after incubation in the medium with CaCl2 and without cyclodextrins indicates occurrence of the true acrosome reaction. Moreover, we suggest the increase of small types of SPACA1 proteins is a valid indicator for occurrence of the acrosomal disintegration arising from the true and false acrosome reactions.

  9. Roles of tumor necrosis factor alpha on sperm acrosin activity and acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    Shu-LingBian; Guo-YiLiu; Hai-XiaWen; Shu-ZhenWang; JiangNi; WeiZhang; HuiSi

    2004-01-01

    Aim: To study the roles of tumor necrosis factor alpha (TNF-a)on the sperm acrosin activity and acrosome reaction. Methods:The sperm acrosin activity was tested by the method of BAEE/ADH Unity and the acrosome reaction by the Triple-stain technique. Results: TNF-a decreased the sperm acrosin activityand acrosome reaction (P<0.01, P<0.01, respectively);

  10. Effect of divalent ions in acrosome reaction induced by glycosamineglycans in porcine spermatozoa.

    Science.gov (United States)

    Delgado, N M; Carranco, A; Merchant, H; Reyes, R

    1985-01-01

    Magnesium, calcium, and zinc at the concentration of 10 microM are capable of inducing a "true" acrosome reaction in the pig spermatozoa judged by the criteria of the fusion of the acrosome and the plasmatic membrane at the anterior region or the sperm nucleus. The optimal percent of acrosome reaction reached by any of the ions tested as a whole was 50%. When glycosamineglycan sulfate (GAGs) plus 10 microM of Mg++, Ca++, or Zn++ was added, they reach to 70-80% of acrosome reaction. At the electrom microscope, thin sections taken from pig spermatozoa treated with ions, GAGs, or ion + GAGs under optimal experimental conditions revealed the same pattern of acrosomal reaction. Results suggest the important role that divalent cations play in general in the induction of the acrosome reaction and question the so-called essential role of calcium ions.

  11. Trehalose enhances osmotic tolerance and suppresses lysophosphatidylcholine-induced acrosome reaction in ram spermatozoon.

    Science.gov (United States)

    Ahmad, E; Naseer, Z; Aksoy, M; Küçük, N; Uçan, U; Serin, I; Ceylan, A

    2015-09-01

    This study was aimed to investigate the influence of trehalose on osmotic tolerance and the ability of ram spermatozoon to undergo acrosome reaction induced by lysophosphatidylcholine (LPC). In experiment 1, the diluted ejaculates were exposed to anisosmotic fructose solutions (70, 500, 750 and 1000 mOsm l(-1) ) with or without 50 mm trehalose. The presence of trehalose in hyperosmotic conditions enhanced (P ram spermatozoon and suppresses their ability to undergo LPC and cryo-induced acrosome reaction.

  12. Effects of No on spontaneous acrosome reaction in AsAb positive rat spermatozoa

    Institute of Scientific and Technical Information of China (English)

    ZhanW; NiJ

    2002-01-01

    Objective:To explore the effect of NO on the spontaneous acrosome reaction in antisperm antibody (AsAb) positive rat spermatozoa.Methods:The rat model of AsAb was set up by artificial immunization.The level of AsAb in blood serum was determined by TAT and ELISA.Rat spermatozoa was visualized by staining the acrosome with Coomassie brilliant blue.The NO concentration in rat spermatozoa was assayed by HPLC.Results:The percentage of acrosome reaction,NO concentration,superoxide dismutase(SOD) and Na+-K+ ATPase activity in AsAb positive rat spermatozoa were significantly decreased compared with the control group.Low dose of NO(SNP 10-9-10-8mol/L) increased the percentage of acrosome reaction and SOD activity,but had no effect on Na+-K+ATPase activity.High dose of NO(SNP 10-6-10-4mol/L) decreased the three items.Conclusion:The decrease in acrosome reaction in positive AsAb rat spermatozoa might be related to a decrease in NO and increase in O2-.(the SOD activity was decreased)in sperm.A low dose of NO might increase the percentage of acrosome reaction in AsAb positive rat by inhibiting the superoxide,while a high dose of NO was harmful to sperm function.

  13. Evidence for the involvement of metalloendoproteases in the acrosome reaction in sea urchin sperm.

    Science.gov (United States)

    Farach, H A; Mundy, D I; Strittmatter, W J; Lennarz, W J

    1987-04-25

    An essential initial step in fertilization in the sea urchin Strongylocentrotus purpuratus is an intracellular membrane fusion event in the sperm known as the acrosome reaction. This Ca2+-dependent, exocytotic process involves fusion of the membrane of the acrosomal vesicle and the plasma membrane. Recently, metalloendoproteases requiring divalent metals have been implicated in several Ca2+-dependent membrane fusion events in other biological systems. In view of the suggested involvement of Zn2+ in the sea urchin sperm acrosome reaction (Clapper, D.L., Davis, J.A., Lamothe, P.J., Patton, C., and Epel, D. (1985) J. Cell Biol. 100, 1817-1824) and the fact that Zn2+ is a metal cofactor for metalloendoproteases, we investigated the potential role of this protease in the acrosome reaction. A soluble metalloendoprotease was demonstrated and characterized in sperm homogenates using the fluorogenic protease substrate succinyl-alanine-alanine-phenylalanine-4-aminomethylcoumarin. The protease was inhibited by the metal chelators EDTA and 1,10-phenanthroline, and activity of the inactive apoenzyme could be reconstituted with Zn2+. The metalloendoprotease substrate and inhibitors blocked the acrosome reaction induced either by egg jelly coat or by ionophore, but had no effect on the influx of Ca2+. These observations suggest that inhibition occurs at a step independent of Ca2+ entry. Overall, the results of this study provide strong indirect evidence that the acrosome reaction requires the action of metalloendoprotease.

  14. Superoxide anion production by human spermatozoa as a part of the ionophore-induced acrosome reaction process.

    Science.gov (United States)

    Griveau, J F; Renard, P; Le Lannou, D

    1995-04-01

    The involvement of superoxide anion (O2o-) in human sperm capacitation and/or acrosome reaction was investigated. Addition of superoxide dismutase (SOD) to the medium at the beginning of the capacitation process or 15 min before induction of the acrosome reaction, decreased the level of ionophore-induced acrosome reaction. Hyperactivation was unaffected by the presence of SOD during the capacitation process. Addition of calcium ionophore to the sperm suspension increased production of O2o- by the spermatozoa by four to five-fold and induced the acrosome reaction. In the presence of SOD, superoxide anion could not be detected in the medium and the rate of induced-acrosome reaction was decreased greatly. The presence of an inhibitor of protein kinase C inhibited the production of O2o- in the medium and reduced the induced-acrosome reaction. The production of O2o- and the acrosome reaction were also increased by exposure of spermatozoa to 12-myristate 13-acetate phorbol ester, a specific activator of protein kinase C. While the level of spontaneous acrosome reaction was not increased by the direct addition of O2o- to the medium, its presence induced the release of unesterified fatty acids from membrane phospholipids. These findings suggest that the production of O2o- by spermatozoa could be involved in the ionophore-induced acrosome reaction, possibly through the de-esterification of membrane phospholipids. However, this production of superoxide anion is not sufficient on its own to induce the acrosome reaction.

  15. Role of ions and ion channels in capacitation and acrosome reaction of spermatozoa

    Institute of Scientific and Technical Information of China (English)

    SharadBPurohit; MaliniLaloraya; G.pradeepkumar

    1999-01-01

    Capacitation and acrosome reaction are important prerequisites of the fertilization process. Capacitation is a highlycomplex phenomenon occurring in the female genital tract, rendering the spermatozoa capable of binding and fusionwith the oocyte. During capacitation various biochemical and biophysical changes occur in the spermatozoa and thespermatozoal membranes. Ions and ion channels also play important roles in governing the process of capacitation bychanging the fluxes of different ions which in turn controls various characteristics of capacitated spermatozoa. Alongwith the mobilization of ions the generation of free radicals and efflux of cholesterol also plays an impo~.nt role in thecapacitation state of the spermatozoa. The generation of free radical and efflux of cholesterol change the mechano-dynamic properties of the membrane by oxidation of the polyunsaturated lipids and by generating the cholesterol freepatches. The process of capacitation renders the spermatozoa responsive to the inducers of the acrosome reaction. Theglycoprotein zona pellucida 3 (ZP3) of the egg coat zona pellucida is the potent physiological stimulator of the acro-some reaction; progesterone, a major component of the follicular fluid, is also an inducer of the acrosome reaction.The inducers of the acrosome reaction cause the activation of the various ion-channels leading to high influxes of calci-um, sodium and bicarbonate. The efflux of cholesterol during the process of capacitation alters the permeability of themembrane to the ions and generate areas which are prone to fusion and ve.siculation process during the acrosome reactioa. this review focuses mainly on effects of the ion and ion-channels, free radicals, and membrane fluidity changesduring the process of capacitation and acrosome reaction.

  16. Dynamics of the induced acrosome reaction in boar sperm evaluated by flow cytometry

    DEFF Research Database (Denmark)

    Birck, Anders; Labouriau, Rodrigo; Christensen, Preben

    2009-01-01

    The present study investigated the dynamics of the in vitro induced acrosome reaction (AR) in boar sperm in response to medium composition, incubation time and ionophore concentration. The AR is a prerequisite for normal sperm fertilizing capability and can be studied in vitro following induction...... induced AR. A detailed description of the dynamics of sperm viability and acrosomal status of boar sperm following in vitro induction of the AR has to our knowledge not previously been conducted. In the present study, a triple color flow cytometric detection technique was used, which gave simultaneous...... information on sperm viability and acrosomal status. The ionophore induced AR was dependent on extracellular Ca2+, but could be easily induced in boar sperm without capacitation. Capacitation-associated plasma membrane phospholipid scrambling was assessed and a medium specific ability to induce these membrane...

  17. Effect of NGF on the motility and acrosome reaction of golden hamster spermatozoa in vitro.

    Science.gov (United States)

    Jin, WanZhu; Tanaka, Akane; Watanabe, Gen; Matsuda, Hiroshi; Taya, Kazuyoshi

    2010-08-01

    Motility and fertilizing ability are known to be two important physiological attributes of a mature sperm, yet the mechanism by which spermatozoa mature and become motile remains largely unknown. It has been shown that nerve growth factor (NGF) is a protein essential for the development, maintenance and survival of the peripheral and central nervous systems. However, the presence of high levels of NGF protein and mRNA do not correlate with the innervations by NGF sensitive fibers in tissues such as the testis, prostate and seminal vesicles. These observations have shifted the attention of research to the role of NGF outside of the nervous system. Here, we demonstrate that NGF and its receptors TrkA and p75 are widely expressed in the testis, accessory reproductive organ, and the epididymal sperms. We also show that NGF stimulates two important aspects of sperm functions, motility and the acrosome reaction, in a time- and dose-dependent manner. NGF activated the sperm cell acrosome reaction, while addition of inhibitors specific for MAPK kinase significantly blocked the sperm acrosome reaction. Taken together, our findings suggest that NGF plays an integral role in sperm motility and the acrosome reaction through, at least in part, the MAPK signalling pathway.

  18. Destabilization of acrosome and elastase influence mediate the release of secretory phospholipase A2 from human spermatozoa

    Institute of Scientific and Technical Information of China (English)

    Jacqueline Leβig; Uta Reibetanz; Jürgen Arnhold; Hans-Jürgen Glander

    2008-01-01

    Aim: To determine the cellular distribution of secretory phospholipase A2 (sPLA2) in dependence on the acrosomal state and under the action of elastase released under inflammatory processes from leukocytes. Methods: Acrosome reaction of spermatozoa was triggered by calcimycin. Human leukocyte elastase was used to simulate in flammatory conditions. To visualize the distribution of sPLA2 and to determine the acrosomal state, immunofluorescence tech-niques and lectin binding combined with confocal laser scanning fluorescence microscopy and flow cytometry were used. Results: Although sPLA2 was detected at the acrosome and tail regions in intact spermatozoa, it disappearedfrom the head region after triggering the acrosome reaction. This release of sPLA2 was associated with enhanced binding of annexin V-fluoroscein isothiocyanate (FITC) to spermatozoa surfaces, intercalation of ethidium-homodimer L and bnding of FITC-iabelled concanavalin A at the acrosomal region. Spermatozoa from healthy subjects treated with elastase were characterized by release of sPLA2, disturbance of acrosome structure, and loss of vitality. Conclusion:The ability of spermatozoa to release secretory phospholipase A2 is related to the acrosomal state. Premature destabi-lization of the acrosome and loss of sPLA2 can occur during silent inflammations in the male genital tract. The distribution pattern of sPLA2 in intact spermatozoa might be an additional parameter for evaluating sperm quality.

  19. Relationship between plasma membrane Ca2+-ATPase activity and acrosome reaction in guinea pig sperm

    Institute of Scientific and Technical Information of China (English)

    李明文; 陈大元

    1996-01-01

    The results obtained by biochemical measurement demonstrated for the first time that significant decrease of the plasma membrane Ca2+-ATPase activity occurred during capacitation and acrosome reaction of guinea pig sperm. Ethaorynic acid, one kind of Ca2+-ATPase antagonists, inhibited the plasma membrane Ca2+-ATPase activity, but calmodulin (50μg/mL) and trifluoperazine (200- 500μmol/L) did not, suggesting that calmodulin is not involved in ATP-driven Ca2+ efflux from sperm. However, calmodulin is involved in the control of Ca2+ influx. TFP, one kind of calmodulin antagonists, accelerated the acrosome reaction and Ca2+ uptake into sperm cells significantly. Ca2+-ATPase antagonists, quercetin, sodium orthovandate, furosemide and ethacrynic acid promoted the acrosome reaction, but inhibited Ca2+ uptake, which cannot be explained by their inhibitory effects on the plasma membrane Ca2+-ATPase activity. It is speculated that this phenomenon might be caused by simultaneous inhibitions of the activities of C

  20. Molecular basis of sperm capacitation acrosome reaction and interaction with eggs

    Energy Technology Data Exchange (ETDEWEB)

    Sheikhnejad, G.

    1985-01-01

    A phospholipase C (PLC) which can hydrolyze /sup 14/C-phosphatidylcholine was purified from bull seminal plasma. This PLC has an optimum at pH 7.2 and its PI was about 5.0. The enzyme was inhibited by EDTA, Cd/sup 2 +/, Pb/sup 2 +/, Ni/sup 2 +/, Fe/sup 2 +/, and Zn/sup 2 +/. PLC consists of two subunits one 69,000 and the other 55,000 daltons. The purified PLC was examined for induction of capacitation and acrosome reaction of guinea pig spermatozoa. Sperm were examined for the acrosome reaction 10 min after addition of 3.4 mM Ca/sup 2 +/. Fifty percent of the sperm underwent the acrosome reaction while the control had less than 5% acrosome reacted sperm. The antiserum to the inneracrosomal membrane isolated from sperm was labeled with FITC conjugated goat anti-guinea pig IgG. The conjugated antibody was used to localize sperm antigens. The antigens located on the IAM were only fluoresced when rabbit sperm were treated with methanol and/or MgCl/sub 2/. Therefore anti-IAM antibody did not bind to the sperm plasma membrane. In vivo capacitated rabbit sperm were incubated with anti-IAM antibody (intact IgG and F(ab')/sub 2/ fragments) for 30 min prior to addition of rabbit eggs. After 24 h the eggs were examined for cleavage. The control eggs were fertilized (90%) while the antibody completely inhibited the fertilization of ova in vitro. The eggs incubated with antibody prior to the addition of sperm were still fertilizable. Thus, anti-IAM did not have any noticeable effect on the eggs. It was also shown that antibody inhibited fertilization of zona-free rabbit eggs in vitro as well.

  1. Insulin and leptin enhance human sperm motility, acrosome reaction and nitric oxide production

    Institute of Scientific and Technical Information of China (English)

    Fanuel Lampiao; Stefan S. du Plessis

    2008-01-01

    Aim: To investigate the in vitro effects of insulin and leptin on human sperm motility, viability, acrosome reaction and nitric oxide (NO) production. Methods: Washed human spermatozoa from normozoospermic donors were treated with insulin (10 μIU) and leptin (10 nmol). Insulin and leptin effects were blocked by inhibition of their intracellular effector, phosphotidylinositol 3-kinase (PI3K), by wortmannin (10 μmol) 30 min prior to insulin and leptin being given. Computer-assisted semen analysis was used to assess motility after 1, 2 and 3 h of incubation. Viability was assessed by fluorescence-activated cell sorting using propidium iodide as a fluorescent probe. Acrosome-reacted cells were observed under a fluorescent microscope using fluorescein-isothiocyanate-Pisum sativum agglutinin as a probe. NO was measured after treating the sperm with 4,5-diaminofluorescein-2/diacetate (DAF-2/DA) and analyzed by fluorescence-activated cell sorting. Results: Insulin and leptin significantly increased total motility, progressive motility and acrosome reaction, as well as NO production. Conclusion: This study showed the in vitro beneficial effects of insulin and leptin on human sperm function. These hormones could play a role in enhancing the fertilization capacity of human spermatozoa.

  2. Induction of the acrosome reaction test to in vitro estimate embryo production in Nelore cattle

    Directory of Open Access Journals (Sweden)

    M.Z. Costa

    2010-08-01

    Full Text Available The effectiveness of induction of the acrosome reaction (AR test as a parameter to in vitro estimate embryo production (IVP in Nelore breed and the AR pattern by the Trypan Blue/Giemsa (TB stain were evaluated. Frozen semen samples from ten Nelore bulls were submitted to AR induction and were also evaluated for cleavage and blastocyst rates. The treatments utilized for AR induction were: control (TALP medium, TH (TALP medium + 10μg heparin, TL (TALP medium + 100μg lysophosphatidylcholine and THL (TALP medium + 10μg heparin + 100μg lysophosphatidylcholine. Sperm acrosomal status and viability were evaluated by TB staining at 0 and after 4h incubation at 38°C. The results obtained for AR presented a significant difference (P<0.05 in the percentage of acrosome reacted live sperm after 4h of incubation in the treatments that received heparin. The cleavage and blastocyst rates were 60% and 38% respectively and a significant difference was observed among bulls (P<0.05. It was founded a satisfactory model to estimate the cleavage and blastocyst rates by AR induction test. Therefore, it can be concluded that the induction of the AR test is a valuable tool to predict the IVP in Nelore breed.

  3. Role and regulation of EGFR in actin remodeling in sperm capacitation and the acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    Haim Breitbart; Nir Etkovitz

    2011-01-01

    To bind and fertilize the egg,the spermatozoon should undergo few biochemical and motility changes in the female reproductive tract collectively called capacitation.The capacitated spermatozoon binds to the egg zona pellucida,and then undergoes the acrosome reaction(AR),which allows its penetration into the egg.The mechanisms regulating sperm capacitation and the AR are not completely understood.In the present review,we summarize some data regarding the role and regulation of the epidermal growth factor receptor(EGFR)in these processes.In the capacitation process,the EGFR is partially activated by protein kinase A(PKA),resulting in phospholipase D(PLD)activation and actin polymerization.Protein kinase C alpha(PKCα),which is already activated at the beginning of the capacitation,also participates in PLD activation.Further activation of the EGFR at the end of the capacitation enhances intracellular Ca2+concentration leading to F-actin breakdown and allows the AR to take place.Under in vivo conditions,the EGFR can be directly activated by its known ligand epidermal growth factor(EGF),and indirectly by activating PKA or by transactivation mediated by G protein-coupled receptors(GPCRs)activation or by ouabain.Under physiological conditions,sperm PKA is activated mainly by bicarbonate,which activates the soluble adenylyl cyclase to produce cyclic adenosine monophosphate(cAMP),the activator of PKA.The GPCR activators angiotensin ll or lysophosphatidic acid,as well as ouabain and EGF are physiological components present in the female reproductive tract.

  4. Mechanism of sperm capacitation and the acrosome reaction: role of protein kinases

    Institute of Scientific and Technical Information of China (English)

    Debby Ickowicz; Maya Finkelstein; Haim Breitbart

    2012-01-01

    Mammalian sperm must undergo a series of biochemical and physiological modifications,collectively called capacitation,in the female reproductive tract prior to the acrosome reaction (AR).The mechanisms of these modifications are not well characterized though protein kinases were shown to be involved in the regulation of intracellular Ca2+ during both capacitation and the AR.In the present review,we summarize some of the signaling events that are involved in capacitation.During the capacitation process,phosphatidyl-inositol-3-kinase (P13K) is phosphorylated/activated via a protein kinase A (PKA)-dependent cascade,and downregulated by protein kinase C α (PKCα).PKCα is active at the beginning of capacitation,resulting in P13K inactivation.During capacitation,PKCα as well as PP1γ2 is degraded by a PKA-dependent mechanism,allowing the activation of P13K.The activation of PKA during capacitation depends mainly on cyclic adenosine monophosphate (cAMP) produced by the bicarbonate-dependent soluble adenylyl cyclase.This activation of PKA leads to an increase in actin polymerization,an essential process for the development of hyperactivated motility,which is necessary for successful fertilization.Actin polymerization is mediated by PIP2 in two ways:first,P(I)P2 acts as a cofactor for phospholipase D (PLD) activation,and second,as a molecule that binds and inhibits actin-severing proteins such as gelsolin.Tyrosine phosphorylation of gelsolin during capacitation by Src family kinase (SFK) is also important for its inactivation.Prior to the AR,gelsolin is released from P(I)P2 and undergoes dephosphorylation/activation,resulting in fast F-actin depolymerization,leading to the AR.

  5. Elucidation of the involvement of p14, a sperm protein during maturation, capacitation and acrosome reaction of caprine spermatozoa.

    Science.gov (United States)

    Nandi, Pinki; Ghosh, Swatilekha; Jana, Kuladip; Sen, Parimal C

    2012-01-01

    Mammalian sperm capacitation is an essential prerequisite to fertilization. Although progress is being made in understanding the physiology and biochemistry of capacitation, little has been yet explored about the potential role(s) of individual sperm cell protein during this process. Therefore elucidation of the role of different sperm proteins in the process of capacitation might be of great importance to understand the process of fertilization. The present work describes the partial characterization of a 14-kDa protein (p14) detected in goat spermatozoa using an antibody directed against the purified protein. Confocal microscopic analysis reveals that the protein is present in both the intracellular and extracellular regions of the acrosomal and postacrosomal portion of caudal sperm head. Though subcellular localization shows that p14 is mainly cytosolic, however it is also seen to be present in peripheral plasma membrane and soluble part of acrosome. Immuno-localization experiment shows change in the distribution pattern of this protein upon induction of capacitation in sperm cells. Increased immunolabeling in the anterior head region of live spermatozoa is also observed when these cells are incubated under capacitating conditions, whereas most sperm cells challenged with the calcium ionophore A23187 to acrosome react, lose their labeling almost completely. Intracellular distribution of p14 also changes significantly during acrosome reaction. Interestingly, on the other hand the antibody raised against this 14-kDa sperm protein enhances the forward motility of caprine sperm cells. Rose-Bengal staining method shows that this anti-p14 antibody also decreases the number of acrosome reacted cells if incubated with capacitated sperm cells before induction of acrosome reaction. All these results taken together clearly indicate that p14 is intimately involved and plays a critical role in the acrosomal membrane fusion event.

  6. Elucidation of the involvement of p14, a sperm protein during maturation, capacitation and acrosome reaction of caprine spermatozoa.

    Directory of Open Access Journals (Sweden)

    Pinki Nandi

    Full Text Available Mammalian sperm capacitation is an essential prerequisite to fertilization. Although progress is being made in understanding the physiology and biochemistry of capacitation, little has been yet explored about the potential role(s of individual sperm cell protein during this process. Therefore elucidation of the role of different sperm proteins in the process of capacitation might be of great importance to understand the process of fertilization. The present work describes the partial characterization of a 14-kDa protein (p14 detected in goat spermatozoa using an antibody directed against the purified protein. Confocal microscopic analysis reveals that the protein is present in both the intracellular and extracellular regions of the acrosomal and postacrosomal portion of caudal sperm head. Though subcellular localization shows that p14 is mainly cytosolic, however it is also seen to be present in peripheral plasma membrane and soluble part of acrosome. Immuno-localization experiment shows change in the distribution pattern of this protein upon induction of capacitation in sperm cells. Increased immunolabeling in the anterior head region of live spermatozoa is also observed when these cells are incubated under capacitating conditions, whereas most sperm cells challenged with the calcium ionophore A23187 to acrosome react, lose their labeling almost completely. Intracellular distribution of p14 also changes significantly during acrosome reaction. Interestingly, on the other hand the antibody raised against this 14-kDa sperm protein enhances the forward motility of caprine sperm cells. Rose-Bengal staining method shows that this anti-p14 antibody also decreases the number of acrosome reacted cells if incubated with capacitated sperm cells before induction of acrosome reaction. All these results taken together clearly indicate that p14 is intimately involved and plays a critical role in the acrosomal membrane fusion event.

  7. Involvement of zinc in the regulation of pHi, motility, and acrosome reactions in sea urchin sperm

    OpenAIRE

    1985-01-01

    When sperm of Strongylocentrotus purpuratus or Lytechinus pictus are diluted into seawater, motility is initiated; and when exposed to egg jelly, an acrosome reaction is induced. In the presence of a variety of structurally different metal chelators (0.1-1 mM EDTA, EGTA, phenanthroline, dipyridyl, cysteine, or dithiothreitol), motility initiation is delayed and the acrosome reaction is inhibited. Of the metals detected in the sperm of these two species, very low levels of Zn+2 (0.1 microM fre...

  8. Assessment of released acrosin activity as a measurement of the sperm acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    Rui-Zhi Liu; Wan-Li Na; Hong-Guo Zhang; Zhi-Yong Lin; Bai-Oong Xue; Zong-Oe Xu

    2008-01-01

    Aim: To develop a method for assessing sperm function by measuring released acrosin activity during the acrosome reaction (AR). Methods: Human semen samples were obtained from 24 healthy donors with proven fertility after 3-7 days of sexual abstinence. After collection, samples were liquefied for 30 min at room temperature. Standard semen parameters were evaluated according to World Health Organization (WHO) criteria. Calcium ionophore A23187 and progesterone (P4) were used to stimulate the sperm to undergo AR. After treatment, sperm were incubated with the supravital dye Hoechst33258, fixed in a glutaraldehyde-phosphate-buffered saline solution, and the acrosomal status was determined by fluorescence microscopy with fluorescein isothiocyanate-labeled Pisum sativum agglutinin (FITC-PSA). The percentage of sperm undergoing AR (AR%) was compared to sperm acrosin activities as assessed by spectrocolorimetry. The correlation between AR% and acrosin activity was determined by statistical analysis. Results: The AR% and released acrosin activity were both markedly increased with A23187 and P4 stimulation. Sperm motility and viability were significantly higher after stimulation with P4 versus stimula-tion with A23187 (P < 0.001). There was a significant positive correlation between released acrosin activity and AR% determined by FITC-PSA staining (r = 0.916, P < 0.001). Conclusion: Spectrocolorimetric measurement of released acrosin activity might serve as a reasonable alternative method to evaluate AR.

  9. Kinetics of human sperm acrosomal exocytosis.

    Science.gov (United States)

    Sosa, C M; Pavarotti, M A; Zanetti, M N; Zoppino, F C M; De Blas, G A; Mayorga, L S

    2015-03-01

    The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.

  10. Fusion of artificial membranes with mammalian spermatozoa. Specific involvement of the equatorial segment after acrosome reaction.

    Science.gov (United States)

    Arts, E G; Kuiken, J; Jager, S; Hoekstra, D

    1993-11-01

    The fusogenic properties of bovine and human spermatozoa membranes were investigated, using phospholipid bilayers (liposomes) as target membranes. Fusion was monitored by following lipid mixing, as revealed by an assay based on resonance-energy transfer. In addition, fusion was visualized by fluorescence microscopy, using fluorescent lipid vesicles. Cryopreserved bovine sperm fused with liposomes before induction of the acrosome reaction, fluorescence being located in essentially all spermatozoa membrane domains. Fresh bovine and human spermatozoa fused with liposomes only after the induction of the acrosome reaction, as triggered by calcium ionophore A23187 or zonae pellucidae (proteins), while the fluorescence distribution was mainly restricted to the equatorial segment (ES). However, with spermatozoa that had undergone a freeze/thawing cycle, domains other than ES also became labeled. Hence, the redistribution of the lipid probes over the entire membrane occurring during lipid mixing with cryopreserved bovine sperm is probably related to membrane perturbations caused by long-term cryopreservation. Fusion with liposomes was governed by spermatozoa factors and required the presence of acidic phospholipids like cardiolipin and phosphatidylserine in the liposomal bilayer. Incorporation of the zwitterionic lipid phosphatidylcholine in the vesicles inhibited the fusion reaction. Fusion was pH dependent. The results indicate that the ES is the primary domain of spermatozoa membranes that harbours the fusogenic capacity of sperm. Liposomes appear a valuable tool in further characterizing the properties of this domain, which has been claimed [Yanagimachi, R. (1988) in The physiology of reproduction (Knobil, E. & Neill, J., eds) pp. 135-185, Raven Press, New York] to represent the putative, initial fusion site for the oocyte.

  11. Identification of egg-jelly substances triggering sperm acrosome reaction in the newt, Cynops pyrrhogaster.

    Science.gov (United States)

    Watanabe, Akihiko; Fukutomi, Keiko; Kubo, Hideo; Ohta, Manami; Takayama-Watanabe, Eriko; Onitake, Kazuo

    2009-04-01

    Our previous studies have shown that the acrosome reaction (AR) occurs in egg-jelly of the Japanese newt, Cynops pyrrhogaster. This is analogous to the substances of echinoderms but distinct from those of many other vertebrates derived from the egg envelope or its derivative, the zona pellucida. To identify the AR-inducing substances in newt egg jelly, a monoclonal antibody (mAb) was generated against the jelly by screening the culture supernatants to find the one that best neutralized the AR-inducing activity of the jelly substance. The mAb specifically reacted to protein bands in the jelly. These proteins, with apparent molecular weights of 122 and 90 kDa, exhibited AR-inducing activity, indicating that they are definitely AR-inducing substances. Western blotting using the mAb indicated that the 122 and 90 kDa proteins are present only in the egg jelly's outermost layer, where AR-inducing activity is known to occur. Both proteins were recognized with wheat germ agglutinin (WGA), a lectin that inhibits AR-induction in egg jelly extract. Taken together, these findings indicate that the 122 and 90 kDa proteins are the AR-inducing substances in the egg jelly of C. pyrrhogaster. The WGA recognition of the proteins was lost by N-glycosidase digestion, suggesting that N-linked carbohydrate moieties in these proteins may be responsible for the AR-inducing activity.

  12. Sperm from hyh mice carrying a point mutation in alphaSNAP have a defect in acrosome reaction.

    Directory of Open Access Journals (Sweden)

    Luis Federico Bátiz

    Full Text Available Hydrocephalus with hop gait (hyh is a recessive inheritable disease that arose spontaneously in a mouse strain. A missense mutation in the Napa gene that results in the substitution of a methionine for isoleucine at position 105 (M105I of alphaSNAP has been detected in these animals. alphaSNAP is a ubiquitous protein that plays a key role in membrane fusion and exocytosis. In this study, we found that male hyh mice with a mild phenotype produced morphologically normal and motile sperm, but had a strongly reduced fertility. When stimulated with progesterone or A23187 (a calcium ionophore, sperm from these animals had a defective acrosome reaction. It has been reported that the M105I mutation affects the expression but not the function of the protein. Consistent with an hypomorphic phenotype, the testes and epididymides of hyh mice had low amounts of the mutated protein. In contrast, sperm had alphaSNAP levels indistinguishable from those found in wild type cells, suggesting that the mutated protein is not fully functional for acrosomal exocytosis. Corroborating this possibility, addition of recombinant wild type alphaSNAP rescued exocytosis in streptolysin O-permeabilized sperm, while the mutant protein was ineffective. Moreover, addition of recombinant alphaSNAP. M105I inhibited acrosomal exocytosis in permeabilized human and wild type mouse sperm. We conclude that the M105I mutation affects the expression and also the function of alphaSNAP, and that a fully functional alphaSNAP is necessary for acrosomal exocytosis, a key event in fertilization.

  13. GABA/progesterone-induced polyphosphoinositide (PPI) breakdown and its role in the acrosome reaction of guinea pig spermatozoa in vitro

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To investigate whether GABA/progesterone (P4) stimulates PPI breakdown and its role in the acrosome reaction (AR), spermatozoa of guinea pig were preincubated in MCM-LCa2+ for 5.5 h and then labeled with [32P]pi for 1 h. Samples were washed through a three-step gradient Percoll, adjusted to 5×107 cells/mL and exposed to 2 mmol/L Ca2+, 5 mmol/L GABA, 10 mmol/L P4 and other agents. Lipids were separated by t.l.c. and radioactivity in spots determined by scintillation counting. The AR was assessed by phase-contrast microscopy. The results showed that (i) when spermato-zoa were treated with GABA, 32P-label diminished rapidly in phosphatidylinositol 4, 5-bisphosphate (PIP2), phosphatidylinositol 4-phosphate (PIP), and increased in phosphatidic acid (PA). The loss of label from PPI was almost completed by 10 min. The time-course of the AR was much slower than PPI when spermatozoa reached a maximal response by 15 min; (ii) the pattern of PPI hydrolysis and stimulation of AR was similar for the three agonists tested;their potency followed the order A23187>progesterone≥GABA; (iii) GABA-induced PIP2 hydrolysis and rise in PA and the AR were prevented by inclusion of 10 mmol/L neomycin; (iv) the loss of PIP2 labeling and the increase in PA labeling abolished when spermatozoa were exposed to EGTA or Ca2+ channel blocker. These re-sults indicate that GABA or P4-induced PPI breakdown is an important and essential event in the series of changes to membrane fusion during the AR of guinea pig spermatozoa and this effect is mediated via calcium by activation of phosphatidylinositol-specific phospholipase C.

  14. Fucose, mannose, and β-N-acetylglucosamine glycopolymers initiate the mouse sperm acrosome reaction through convergent signaling pathways.

    Science.gov (United States)

    Wu, Linghui; Sampson, Nicole S

    2014-02-21

    The sperm acrosome reaction (AR), an essential exocytosis step in mammalian fertilization, is mediated by a species-specific interaction of sperm surface molecules with glycans on the egg. Previous studies indicate that a subset of terminal carbohydrates on the mouse egg zona pellucida (ZP) trigger the AR by cross-linking or aggregating receptors on the sperm membrane. However, the exact role of those carbohydrates in AR has not been identified and the mechanism underlying the AR still needs further investigation. To study this process, a series of glycopolymers was synthesized. The glycopolymers are composed of a multivalent scaffold (norbornene), a functional ligand (previously identified ZP terminal monosaccharides), and a linker connecting the ligand and the scaffold. The polymers were tested for their ability to initiate AR and through which signaling pathways AR induction occurred. Our data demonstrate that mannose, fucose, and β-N-acetylglucosamine 10-mers and 100-mers initiate AR in a dose-dependent manner, and the 100-mers are more potent on a per monomer basis than the 10-mers. Although nearly equipotent in inducing the AR at the optimal concentrations, their AR activation kinetics are not identical. Similar to mouse ZP3, all 100-mer-activated AR are sensitive to guanine-binding regulatory proteins (G-proteins), tyrosine kinase, protein kinase A, protein kinase C, and Ca(2+)-related antagonists. Thus, the chemotypes of synthetic glycopolymers imitate the physiologic AR-activation agents and provide evidence that occupation of one of at least three different receptor binding sites is sufficient to initiate the AR.

  15. Surface mapping of binding of oviductin to the plasma membrane of golden hamster spermatozoa during in vitro capacitation and acrosome reaction.

    Science.gov (United States)

    Kan, Frederick W K; Esperanzate, Patrick W B

    2006-06-01

    Oviductins are high-molecular-weight glycoproteins synthesized and secreted by nonciliated oviductal epithelial cells and have been shown to play a role in fertilization and early embryo development. The present study was carried out to examine the in vitro binding capacity of hamster oviductin to homologous sperm and to determine the sites of its localization in untreated, capacitated, and acrosome-reacted spermatozoa. Freshly prepared epididymal and capacitated sperm as well as acrosome-reacted sperm were incubated with oviductal fluid prepared from isolated hamster oviducts, fixed and then probed with a monoclonal antibody against hamster oviductin. Results obtained with pre-embedding immunolabeling experiments revealed binding of oviductin to the acrosomal cap and the apical aspect of the postacrosomal region. Immunolabeling of both regions appeared to be more intense in capacitated spermatozoa. Acrosome-reacted sperm showed an immunoreaction of moderate intensity over the postacrosomal region. The plasma membrane overlying the equatorial segment also exhibited a weak labeling. Quantitative analysis obtained with the surface replica technique indicated that oviductin had a higher binding affinity for the acrosomal cap than the postacrosomal region and that the binding of oviductin to the latter plasma membrane domain was enhanced during capacitation. Binding of oviductin to the postacrosomal region, however, was attenuated after acrosome reaction. Immunolabeling for oviductin was found to be the weakest over the equatorial segment regardless of the experimental conditions. The binding of hamster oviductin to specific membrane domains of the homologous sperm and the changes in its distribution during capacitation and acrosome reaction may be important for the function of hamster oviductin preceding and during fertilization.

  16. P38 participates in spermatogenesis and acrosome reaction prior to fertilization in Chinese mitten crab Eriocheir sinensis.

    Science.gov (United States)

    Zhu, Ming; Sun, Wen-Juan; Wang, Yuan-Li; Li, Qing; Yang, Hong-Dan; Duan, Ze-Lin; He, Lin; Wang, Qun

    2015-04-01

    P38 mitogen-activated protein kinases (MAPKs) comprise a family of serine/threonine protein kinases that play important roles in cellular responses to inflammatory cytokines and environmental stresses. These kinases are involved in controlling cell division, differentiation and death in mammalian testes and therefore are critical to spermatogenesis. To explore their functions in male reproduction of Chinese mitten crabs, Eriocheir sinensis p38 (Es-p38) protein expression was determined in different tissues including testes at different developmental stages by Western blot. Es-p38 was expressed in various tissues, with higher levels in the heart, stomach, gills and testes. Total Es-p38 protein levels increased gradually during spermatogenesis, but phosphorylated Es-p38 was much higher in the spermatid (August-October) than the spermatocyte (July-August) and sperm (October-January) stages. Trypan blue staining and hematoxylin/eosin staining were both used to detect sperm motility and changes in sperm morphology during the acrosome reaction (AR) induced by pre-incubation with A23187 in vitro, activated Es-p38 proteins detected by fluorescent microscopy were translocated gradually to nuclear and apical cap regions, accumulating at the anterior of the acrosomal tubule. The results suggest the involvement of p38 MAPK in spermatogenesis and the AR in E. sinensis.

  17. Dose-response effects of estrogenic mycotoxins (zearalenone, alpha- and beta-zearalenol on motility, hyperactivation and the acrosome reaction of stallion sperm

    Directory of Open Access Journals (Sweden)

    Colenbrander Ben

    2011-10-01

    Full Text Available Abstract Background The aim of this study was to investigate the in vitro effects of the Fusarium fungus-derived mycotoxin, zearalenone and its derivatives alpha-zearalenol and beta-zearalenol on motility parameters and the acrosome reaction of stallion sperm. Since the toxic effects of zearalenone and its derivatives are thought to result from their structural similarity to 17beta-estradiol, 17beta-estradiol was used as a positive control for 'estrogen-like' effects. Methods Stallion spermatozoa were exposed in vitro to zearalenone, alpha-zearalenol, beta-zearalenol or 17beta-estradiol at concentrations ranging from 1 pM - 0.1 mM. After 2 hours exposure, motility parameters were evaluated by computer-assisted analysis, and acrosome integrity was examined by flow cytometry after staining with fluoroscein-conjugated peanut agglutinin. Results Mycotoxins affected sperm parameters only at the highest concentration tested (0.1 mM after 2 hours exposure. In this respect, all of the compounds reduced the average path velocity, but only alpha-zearalenol reduced percentages of motile and progressively motile sperm. Induction of motility patterns consistent with hyperactivation was stimulated according to the following rank of potency: alpha-zearalenol >17beta-estradiol > zearalenone = beta-zearalenol. The hyperactivity-associated changes observed included reductions in straight-line velocity and linearity of movement, and an increase in the amplitude of lateral head displacement, while curvilinear velocity was unchanged. In addition, whereas alpha- and beta- zearalenol increased the percentages of live acrosome-reacted sperm, zearalenone and 17beta-estradiol had no apparent effect on acrosome status. In short, alpha-zearalenol inhibited normal sperm motility, but stimulated hyperactive motility in the remaining motile cells and simultaneously induced the acrosome reaction. Beta-zearalenol induced the acrosome reaction without altering motility

  18. Con A-binding protein Zn-α2-glycoprotein on human sperm membrane is related to acrosome reaction and sperm fertility.

    Science.gov (United States)

    Liu, Y; Qu, F; Cao, X; Chen, G; Guo, Q; Ying, X; Guo, W; Lu, L; Ding, Z

    2012-04-01

    Fertilization, the recognition and fusion between spermatozoa and oocyte, involves various molecules on the spermatozoa and oocyte membranes. Concanavalin A (ConA)-binding proteins may be one of the molecules involved in mammal spermatozoa fertilization; however, their structure and function remain largely unknown. Here, we initially identified a ConA-binding protein, Zn-α2-glycoprotein (ZAG), involved in regulating the acrosome reaction (AR) of human spermatozoa. ZAG is localized on the pre-equatorial region covering the acrosome, neck and tail (some parts of middle piece and principal piece respectively) regions of the acrosome intact human spermatozoa, and disappears in the acrosomal region of the acrosome-reacted spermatozoa. Polyclonal antibodies against human recombinant ZAG significantly reduced the AR and sperm capability binding to human zona pellucida or penetration into zona-free hamster oocytes. Furthermore, assessment of the signaling pathways regulated by ZAG revealed that ZAG affects sperm AR through both the cAMP/PKA and PKC pathways. These results indicate that ZAG, which is present on the human sperm membrane, plays a critical role in the AR and subsequently, may be involved in sperm fertility.

  19. Effects of ubiquitin-protea some pathway on mouse sperm capacitation, acrosome reaction and in vitro fertilization

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Chlortetracycline (CTC) fluorescence patterns were used to study changes in the patterns B and AR of mouse sperm after incubation with reagents that would block the UPP. They were the monoclonal antibody against ubiquitinated proteins-UCP1; the polyclonal antibody against ubiquitin anti-Ub, and a special inhibitor against proteasome ALLN. Furthermore, we treated the capacitated sperm or the eggs with these reagents separately and tested whether the normal in vitro fertilization was blocked or not. Results illustrate that UCP1, anti-Ub, and ALLN have little effects on sperm capacitation and acrosome reaction,but they do inhibit fusion of mouse sperm with eggs, which suggests that UPP play an important role in mouse in vitro fertilization.``

  20. RIM, Munc13, and Rab3A interplay in acrosomal exocytosis

    Energy Technology Data Exchange (ETDEWEB)

    Bello, Oscar D.; Zanetti, M. Natalia [Laboratorio de Biologia Celular y Molecular, Instituto de Histologia y Embriologia, IHEM (CONICET-UNCuyo), Facultad de Ciencias Medicas (Argentina); Laboratorio de Biologia Reproductiva, Instituto de Histologia y Embriologia, IHEM (CONICET-UNCuyo), Facultad de Ciencias Medicas (Argentina); Mayorga, Luis S. [Laboratorio de Biologia Celular y Molecular, Instituto de Histologia y Embriologia, IHEM (CONICET-UNCuyo), Facultad de Ciencias Medicas (Argentina); Michaut, Marcela A., E-mail: mmichaut@fcm.uncu.edu.ar [Laboratorio de Biologia Reproductiva, Instituto de Histologia y Embriologia, IHEM (CONICET-UNCuyo), Facultad de Ciencias Medicas (Argentina); Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza (5500) (Argentina)

    2012-03-10

    Exocytosis is a highly regulated, multistage process consisting of multiple functionally definable stages, including recruitment, targeting, tethering, priming, and docking of secretory vesicles with the plasma membrane, followed by calcium-triggered membrane fusion. The acrosome reaction of spermatozoa is a complex, calcium-dependent regulated exocytosis. Fusion at multiple sites between the outer acrosomal membrane and the cell membrane causes the release of the acrosomal contents and the loss of the membranes surrounding the acrosome. Not much is known about the molecules that mediate membrane docking in this particular fusion model. In neurons, the formation of the ternary RIM/Munc13/Rab3A complex has been suggested as a critical component of synaptic vesicles docking. Previously, we demonstrated that Rab3A localizes to the acrosomal region in human sperm, stimulates acrosomal exocytosis, and participates in an early stage during membrane fusion. Here, we report that RIM and Munc13 are also present in human sperm and localize to the acrosomal region. Like Rab3A, RIM and Munc13 participate in a prefusion step before the efflux of intra-acrosomal calcium. By means of a functional assay using antibodies and recombinant proteins, we show that RIM, Munc13 and Rab3A interplay during acrosomal exocytosis. Finally, we report by electron transmission microscopy that sequestering RIM and Rab3A alters the docking of the acrosomal membrane to the plasma membrane during calcium-activated acrosomal exocytosis. Our results suggest that the RIM/Munc13/Rab3 A complex participates in acrosomal exocytosis and that RIM and Rab3A have central roles in membrane docking. -- Highlights: Black-Right-Pointing-Pointer RIM and Munc13 are present in human sperm and localize to the acrosomal region. Black-Right-Pointing-Pointer RIM and Munc13 are necessary for acrosomal exocytosis. Black-Right-Pointing-Pointer RIM and Munc13 participate before the acrosomal calcium efflux. Black

  1. Mouse sperm patch-clamp recordings reveal single Cl- channels sensitive to niflumic acid, a blocker of the sperm acrosome reaction.

    Science.gov (United States)

    Espinosa, F; de la Vega-Beltrán, J L; López-González, I; Delgado, R; Labarca, P; Darszon, A

    1998-04-10

    Ion channels lie at the heart of gamete signaling. Understanding their regulation will improve our knowledge of sperm physiology, and may lead to novel contraceptive strategies. Sperm are tiny (approximately 3 microm diameter) and, until now, direct evidence of ion channel activity in these cells was lacking. Using patch-clamp recording we document here, for the first time, the presence of cationic and anionic channels in mouse sperm. Anion selective channels were blocked by niflumic acid (NA) (IC50 = 11 microM). The blocker was effective also in inhibiting the acrosome reaction induced by the zona pellucida, GABA or progesterone. These observations suggest that Cl- channels participate in the sperm acrosome reaction in mammals.

  2. A Unique 2-Sulfated β-Galactan from the Egg Jelly of the Sea Urchin Glyptocidaris crenularis: CONFORMATION FLEXIBILITY VERSUS INDUCTION OF THE SPERM ACROSOME REACTION*

    OpenAIRE

    Castro, Michelle O.; Pomin, Vitor H.; Santos, Livia L.; Ana-Cristina E.S. Vilela-Silva; Hirohashi, Noritaka; Pol-Fachin, Laércio; Verli,Hugo; Mourão, Paulo A. S.

    2009-01-01

    Sulfated polysaccharides from the egg jelly of sea urchins act as species-specific inducers of the sperm acrosome reaction, which is a rare molecular mechanism of carbohydrate-induced signal-transduction event in animal cells. The sea urchin polysaccharides differ in monosaccharide composition (l-fucose or l-galactose), glycosylation, and sulfation sites, but they are always in the α-anomeric configuration. Herein, structural analysis of the polysaccharide from the sea urchin Glyptocidaris cr...

  3. Relationship between seminal plasma zinc concentration and spermatozoa–zona pellucida binding and the ZP-induced acrosome reaction in subfertile men

    OpenAIRE

    Liu, De-Yi; Sie, Boon-Shih; Liu, Ming-Li; Agresta,Franca; Baker, HW Gordon

    2009-01-01

    The aim of this study was to determine the relationship between seminal zinc concentration and spermatozoa–zona pellucida (ZP) binding and the ZP-induced acrosome reaction (ZPIAR) in subfertile men. Semen analyses and seminal zinc concentration assessments were carried out according to the World Health Organization manual for 458 subfertile men. A spermatozoa–ZP interaction test was carried out by incubating 2 × 106 motile spermatozoa with a group of four unfertilized oocytes obtained from a ...

  4. Structural requirements for species-specific induction of the sperm acrosome reaction by sea urchin egg sulfated fucan.

    Science.gov (United States)

    Hirohashi, Noritaka; Vilela-Silva, Ana-Cristina E S; Mourão, Paulo A S; Vacquier, Victor D

    2002-11-01

    The sulfated fucan (SF) of egg jelly induces the acrosome reaction (AR) of sea urchin sperm. Strongylocentrotus franciscanus (Sf) SF is sulfated only at the 2-position. Strongylocentrotus purpuratus (Sp) has two SF isotypes, each one being female specific. One is rich in sulfate at both the 2- and 4-positionS (SF-1), and the other is rich in sulfate at the 4-position, but not the 2-position (SF-2). Sf SF is poor at inducing the AR of Sp sperm, presumably due to lack of 4-sulfation. Sp SF-1 is better at inducing the AR of Sf sperm than Sp SF-2, hypothetically due to increased 2-sulfation. Chemical oversulfation of Sf SF increases the percentage of AR of Sp sperm, showing that 4-sulfation is important for recognition of SF by Sp sperm. Chemically oversulfated Sp SF-2 is better at inducing the Sf sperm AR, presumably because of increased 2-sulfation. The species, Strongylocentrotus drobachiensis (Sd), has an SF-2 that is exclusively 2-sulfated (like Sf), except the glycosidic linkage in Sd is alpha(1-->4), whereas in Sf it is alpha(1-->3). Sd SF-2 does not induce the AR of Sf sperm, showing the strict requirement for the alpha(1-->3) linkage in recognition between Sf sperm and SF. Egg jelly from Echinometra lucunter (El) contains sulfated galactan (SG) which differs from Sf SF only in that the monosaccharide is L-galactose, not L-fucose. This SG and Sf SF are equally potent in inducing the AR of Sf sperm, showing that modification at C6 of L-fucose is not important for proper recognition between SF and Sf sperm receptors. This system permits study of the structural basis for recognition between sulfated polysaccharide and receptors controlling signal transduction pathways in animal cells.

  5. The opening of maitotoxin-sensitive calcium channels induces the acrosome reaction in human spermatozoa: differences from the zona pellucida

    Institute of Scientific and Technical Information of China (English)

    Julio C Chávez; Claudia L Trevi(n)o; Gerardo A de Blas; José L de la Vega-Beltrán; Takuya Nishigaki; Mayel Chirinos; María Elena González-González; Fernando Larrea; Alejandra Solís; Alberto Darszon

    2011-01-01

    The acrosome reaction(AR),an absolute requirement for spermatozoa and egg fusion,requires the influx of Ca2+into the spermatozoa through voltage-dependent Ca2+channels and store-operated channels.Maitotoxin(MTx),a Ca2+-mobilizing agent,has been shown to be a potent inducer of the mouse sperm AR,with a pharmacology similar to that of the zona pellucida(ZP),possibly suggesting a common pathway for both inducers.Using recombinant human ZP3(rhZP3),mouse ZP and two MTx channel blockers(U73122 and U73343),we investigated and compared the MTx-and ZP-induced ARs in human and mouse spermatozoa.Herein,we report that MTx induced AR and elevated intracellular Ca2+([Ca2+]1)in human spermatozoa,both of which were blocked by U73122 and U73343.These two compounds also inhibited the MTx-induced AR in mouse spermatozoa.In disagreement with our previous proposal,the AR triggered by rhZP3 or mouse ZP was not blocked by U73343,indicating that in human and mouse spermatozoa,the AR induction by the physiologicalligands or by MTx occurred through distinct pathways.U73122,but not U73343(inactive analogue),can block phospholipase C(PLC).Another PLC inhibitor,edelfosine,also blocked the rhZP3-and ZP-induced ARs.These findings confirmed the participation of a PLC-dependent signalling pathway in human and mouse zona protein-induced AR.Notably,edelfosine also inhibited the MTx-induced mouse sperm AR but not that of the human,suggesting that toxin-induced AR is PLC-dependent in mice and PLC-independent in humans.

  6. Cryopreservation of human spermatozoa. I. Effects of holding procedure and seeding on motility, fertilizability, and acrosome reaction.

    Science.gov (United States)

    Critser, J K; Huse-Benda, A R; Aaker, D V; Arneson, B W; Ball, G D

    1987-04-01

    Three experiments were conducted to evaluate effects of holding semen at +5.0 degrees C for 30 minutes or -5.0 degrees C for 10 minutes and ice crystal induction (seeding) on frozen-thawed human spermatozoa. In experiment 1, spermatozoa were frozen, and postthaw motility was evaluated immediately (0 hour) and 24 hours later. At both 0 and 24 hours, nonfrozen control samples had higher motility than all other treatment groups. At 0 hour postthaw, motility was higher in samples held at -5.0 degrees C for 10 minutes with no significant effect of seeding. At 24 hours, samples held at -5.0 degrees C for 10 minutes and seeded, but not samples held at -5.0 degrees C and not seeded, had higher motility than samples held at +5.0 degrees C. In experiment 2, semen samples were frozen, and fertilizability was evaluated in a zona-free hamster egg penetration assay. Seeded samples had a higher frequency of sperm penetration than either nonfrozen or nonseeded samples. In experiment 3, nonfrozen controls and frozen treatment groups were evaluated for the frequency of survival and acrosomal integrity. Seeded samples had higher frequencies of survival and loss of acrosomal integrity than nonseeded samples. All frozen-thawed samples had a lower frequency of survival and a higher frequency of loss of acrosomal integrity than nonfrozen controls. Although altered patterns of fertilizability and acrosomal integrity are induced, collectively these data suggest that incorporating a holding temperature of -5.0 degrees C for 10 minutes and seeding may result in a superior protocol for freezing human spermatozoa.

  7. A unique 2-sulfated {beta}-galactan from the egg jelly of the sea urchin Glyptocidaris crenularis: conformation flexibility versus induction of the sperm acrosome reaction.

    Science.gov (United States)

    Castro, Michelle O; Pomin, Vitor H; Santos, Livia L; Vilela-Silva, Ana-Cristina E S; Hirohashi, Noritaka; Pol-Fachin, Laércio; Verli, Hugo; Mourão, Paulo A S

    2009-07-10

    Sulfated polysaccharides from the egg jelly of sea urchins act as species-specific inducers of the sperm acrosome reaction, which is a rare molecular mechanism of carbohydrate-induced signal-transduction event in animal cells. The sea urchin polysaccharides differ in monosaccharide composition (l-fucose or l-galactose), glycosylation, and sulfation sites, but they are always in the alpha-anomeric configuration. Herein, structural analysis of the polysaccharide from the sea urchin Glyptocidaris crenularis surprisingly revealed a unique sulfated beta-d-galactan composed by (3-beta-d-Galp-2(OSO(3))-1-->3-beta-d-Galp-1)(n) repeating units. Subsequently, we used the G. crenularis galactan to compare different 2-sulfated polysaccharides as inducers of the acrosome reaction using homologous and heterologous sperm. We also tested the effect of chemically over-sulfated galactans. Intriguingly, the anomeric configuration of the glycosidic linkage rather than the monosaccharide composition (galactose or fucose) is the preferential structural requirement for the effect of these polysaccharides on sea urchin fertilization. Nuclear magnetic resonance and molecular dynamics indicate that sulfated alpha-galactan or alpha-fucan have less dynamic structural behavior, exhibiting fewer conformational populations, with an almost exclusive conformational state with glycosidic dihedral angles Phi/Psi = -102 degrees /131 degrees . The preponderant conformer observed in the sulfated alpha-galactan or alpha-fucan is not observed among populations in the beta-form despite its more flexible structure in solution. Possibly, a proper spatial arrangement is required for interaction of the sea urchin-sulfated polysaccharides with the specific sperm receptor.

  8. Genome-wide association study implicates testis-sperm specific FKBP6 as a susceptibility locus for impaired acrosome reaction in stallions.

    Directory of Open Access Journals (Sweden)

    Terje Raudsepp

    Full Text Available Impaired acrosomal reaction (IAR of sperm causes male subfertility in humans and animals. Despite compelling evidence about the genetic control over acrosome biogenesis and function, the genomics of IAR is as yet poorly understood, providing no molecular tools for diagnostics. Here we conducted Equine SNP50 Beadchip genotyping and GWAS using 7 IAR-affected and 37 control Thoroughbred stallions. A significant (PA and g.11040379C>A (p.166H>N in exon 4 that were significantly associated with the IAR phenotype both in the GWAS cohort (n = 44 and in a large multi-breed cohort of 265 horses. All IAR stallions were homozygous for the A-alleles, while this genotype was found only in 2% of controls. The equine FKBP6 was exclusively expressed in testis and sperm and had 5 different transcripts, of which 4 were novel. The expression of this gene in AC/AG heterozygous controls was monoallelic, and we observed a tendency for FKBP6 up-regulation in IAR stallions compared to controls. Because exon 4 SNPs had no effect on the protein structure, it is likely that FKBP6 relates to the IAR phenotype via regulatory or modifying functions. In conclusion, FKBP6 was considered a susceptibility gene of incomplete penetrance for IAR in stallions and a candidate gene for male subfertility in mammals. FKBP6 genotyping is recommended for the detection of IAR-susceptible individuals among potential breeding stallions. Successful use of sperm as a source of DNA and RNA propagates non-invasive sample procurement for fertility genomics in animals and humans.

  9. The Relationship between Some Ions and Acrosome Reactionof Human Sperm

    Institute of Scientific and Technical Information of China (English)

    王春年; 谢文英; 徐胜; 王一飞

    1994-01-01

    The acrosome reaction of sperm was induced by calcium ionophore A 23187. The relationship between some ions and acrosome reaction by removing Na+ from the medium,or by adding antagonist of K+, TEA chloride, or antagonist of Ca++, verapamiI, or antagonist of Na+-h+-ATPase, acetyl strophanthidin is studied The results show that Na+,K+, Ca++ and Na+ pump are necessary for acrosome reaction of human sperm. The Ca++ might not enter the sperms through the channel of Ca++.

  10. The effects of ZAG on the acrosome reaction (AR) of human spermatozoa%锌-α2糖蛋白在人精子顶体反应过程中的作用

    Institute of Scientific and Technical Information of China (English)

    郭毅; 刘悦; 王羽; 滕晓明

    2013-01-01

    Objective To explore the effects of ZAG(Zn-alpha2-glycoprotein) on the process of AR. Methods Indirect immunofluorescence and spermatozoa-ZP binding tests were used to analyze the effects of ZAG on human sperm acrosome reaction. Results Immunofluorescence staining revealed intensive immunoreactivity of ZAG in the acrosomal region was largely reduced in acrosome reacted spermatozoa, and human spermatozoa-ZP binding test indicated the spermatozoa’ s ability binding to ZP significantly decreased in spermatozoa treated with anti-ZAG antibody. Conclusion ZAG has significant effects on the acrosome reaction and the spermatozoa-ZP binding.%目的:初步探讨锌-α2糖蛋白(ZAG)在人精子顶体反应中的作用。方法采用ZAG抗体对人精子进行免疫荧光染色,激光共聚焦显微镜观察ZAG在顶体反应前后定位的变化,并通过精子透明带结合实验进一步证明ZAG在顶体反应中的作用。结果顶体反应后精子顶体头部的ZAG荧光明显下降甚至消失。精子经ZAG抗体处理后,其透明带结合能力显著下降。结论 ZAG在人精子顶体反应中发挥一定的作用,并影响人精子的透明带结合能力。本研究为探索ZAG在受精过程中的功能及分子作用机制奠定基础。

  11. In vitro induction of the acrosome reaction in bull sperm and the relationship to field fertility using low-dose inseminations

    DEFF Research Database (Denmark)

    Birck, A; Christensen, P; Labouriau, R

    2010-01-01

    . Furthermore, large-scale fertility trials using low-dose inseminations are pending. In the current study, the relationship between field fertility and the in vitro-induced AR was investigated using three ejaculates from each of 195 bulls, 156 Holstein and 39 Jersey bulls (Bos taurus), participating...... inseminations in 4721 herds and 208 artificial insemination (AI) technicians. Simultaneous detection of sperm viability and acrosomal status was achieved using a triple color flow cytometric technique. Sperm samples from the bulls displayed a wide range of ability to acrosome react in response to calcium...

  12. Relationship between seminal plasma zinc concentration and spermatozoa-zona pellucida binding and the ZP-induced acrosome reaction in subfertile men.

    Science.gov (United States)

    Liu, De-Yi; Sie, Boon-Shih; Liu, Ming-Li; Agresta, Franca; Baker, H W Gordon

    2009-07-01

    The aim of this study was to determine the relationship between seminal zinc concentration and spermatozoa-zona pellucida (ZP) binding and the ZP-induced acrosome reaction (ZPIAR) in subfertile men. Semen analyses and seminal zinc concentration assessments were carried out according to the World Health Organization manual for 458 subfertile men. A spermatozoa-ZP interaction test was carried out by incubating 2 x 10(6) motile spermatozoa with a group of four unfertilized oocytes obtained from a clinical in vitro fertilization programme. After 2 h of incubation, the number of spermatozoa bound per ZP and the ZPIAR of ZP-bound spermatozoa were examined. The effect of adding 0.5 mmol L(-1) zinc to the media on the ZPIAR of spermatozoa from normozoospermic men was also tested in vitro. Seminal zinc concentration positively correlated with sperm count and duration of abstinence, but negatively correlated with semen volume. On analysis of data from all participants, both spermatozoa-ZP binding and the ZPIAR were significantly correlated with sperm motility and normal morphology, but not with seminal zinc concentration. However, in men with normozoospermic semen, the seminal zinc concentration was significantly higher in men with defective ZPIAR (or= 16%) (P zinc to the culture media had no effect on spermatozoa-ZP binding, but significantly reduced the ZPIAR in vitro (P zinc concentration is correlated with sperm count and the duration of abstinence in subfertile men. In men with normozoospermic semen, high seminal zinc concentration may have an adverse effect on the ZPIAR.

  13. Protein tyrosine phosphorylation, hyperactivation and progesterone-induced acrosome reaction are enhanced in IVF media: an effect that is not associated with an increase in protein kinase A activation.

    Science.gov (United States)

    Moseley, F L C; Jha, K N; Björndahl, Lars; Brewis, I A; Publicover, S J; Barratt, C L R; Lefièvre, L

    2005-07-01

    Sperm capacitation is a prerequisite for successful in vitro fertilization (IVF) and therefore a focus of sperm preparation in IVF laboratories. The technology of IVF is, therefore, potentially valuable in advancing our understanding of the molecular processes that occur during sperm capacitation. We have investigated sperm capacitation induced by a commercial IVF medium compared to that occurring in standard capacitating medium (CM) typically used in a nonclinical setting. Percoll-washed spermatozoa were resuspended in Cook Sydney IVF medium, Cook Sydney IVF sperm buffer, Earle's balanced salt medium (capacitating medium) or a modified Earle's balanced salt medium [non-capacitating medium (NCM)] for up to 120 min at 37 degrees C and, if applicable, in the presence of 5% CO2 in air. Sperm protein kinase A (PKA) activity, PKA-dependent serine/threonine phosphorylation, tyrosine phosphorylation, hyperactivation and progesterone-induced acrosome reaction were evaluated. IVF medium was shown to accelerate sperm capacitation (compared with capacitating medium) as determined by tyrosine phosphorylation, sperm hyperactivation and progesterone-induced acrosome reaction. This effect was not associated with enhanced activation of PKA or increased levels of serine/threonine phosphorylation. In contrast, IVF sperm buffer (used for sperm preparation) did not stimulate sperm capacitation when incubated for up to 90 min. We have shown that different capacitating media vary strikingly in their efficacy and that this difference reflects activation of a pathway other than the well-characterized activation of soluble adenylyl cyclase/cAMP/PKA.

  14. Identification of bovine sperm acrosomal proteins that interact with a 32-kDa acrosomal matrix protein.

    Science.gov (United States)

    Nagdas, Subir K; Smith, Linda; Medina-Ortiz, Ilza; Hernandez-Encarnacion, Luisa; Raychoudhury, Samir

    2016-03-01

    reaction, whereas the IZUMO1 and lactadherin polypeptides remain associated to the particulate fraction. Almost entire population of bovine sperm IZUMO1 relocates to the equatorial segment during the LPC-induced acrosome reaction. We propose that the interaction of OMC32 matrix polypeptide with detergent-soluble acrosomal proteins regulates the release of hydrolases/other acrosomal protein(s) during the acrosome reaction.

  15. The acrosomal matrix from guinea pig sperm contains structural proteins, suggesting the presence of an actin skeleton.

    Science.gov (United States)

    Zepeda-Bastida, Armando; Chiquete-Felix, Natalia; Uribe-Carvajal, Salvador; Mujica, Adela

    2011-01-01

    The mammalian sperm acrosome contains a large number of hydrolytic enzymes. When the acrosomal reaction and fertilization occur, these enzymes are released in an orderly fashion, suggesting that the acrosomal matrix is highly organized. It was decided to determine the identity of the structural scaffold underlying the organization of the acrosome. In permeabilized acrosomes and in the Triton X-100-extracted acrosomal matrices from guinea pig sperm, we used indirect immunofluorescence, immunogold labeling, and Western blotting to identify F-actin, spectrin, myosin, calmodulin, and gelsolin. These proteins were detected in the acrosomal matrix for the first time. In noncapacitated, intact spermatozoa the addition of the F-actin monomerizing agent cytochalasin D resulted in loss of the acrosome, suggesting that F-actin is needed to preserve an intact acrosome. Our results suggest that the acrosomal architecture is supported by a dynamic F-actin skeleton, which probably regulates the differential rate of release of the acrosomal enzymes during acrosomal reaction and fertilization.

  16. Inhibition of mouse acrosome reaction and sperm-zona pellucida binding by anti-human sperm membrane protein 1 antibody%抗人精子膜蛋白抗体1对小鼠精子顶体反应和精子-透明带结合的抑制作用

    Institute of Scientific and Technical Information of China (English)

    G.Y.Cheng; J.L.Shi; M.Wang; Y.Q.Hu; C.M.Liu; Y.F.Wang; C.Xu

    2007-01-01

    Aim:To investigate the possible functions of human sperm membrane protein (hSMP-1) in the process of fertilization.Methods: A 576-bp cDNA fragment of HSD-1 gene coding for the extracellular domain of hSMP-1 was cloned and expressed. The localization of this protein on human and mouse sperm was determined by indirect immunofluorescent staining by using anti-recombinant hSMP-1 (anti-rhSMP-1) antibodies. Sperm acrosome reaction and spermzona pellucida (ZP) binding assay were carried out in 10-week-old BALB/c mice. Results: Recombinant hSMP-1 was successfully cloned and expressed. The expression of the native protein was limited on the acrosome of human and mouse sperm. Treatment of anti-rhSMP-1 antibodies significantly decreased the average number of sperms bound to each egg. Meanwhile, the percentage of acrosome reaction was decreased in comparison to pre-immune control after treatment with anti-rhSMP-1 (P < 0.05). Conclusion: The results suggest that anti-rhSMP-1 antibody inhibited mouse acrosome reaction and sperm-ZP binding.

  17. The acrosome of eutherian mammals.

    Science.gov (United States)

    Fléchon, Jacques-Edmond

    2016-01-01

    The acrosome is not just a bag of enzymes, most of which, if not all, are singly non-essential for sperm-oocyte interaction. The Golgi-derived acrosomal cap reveals some extraordinary development and structure particularities. The acrosome of eutherian spermatozoa basically consists of two parts, the anterior and equatorial segments; the present review is devoted to the former, the initial actor in fertilization. Its occasional fanciful morphological changes during epididymal maturation are analyzed, together with its heterogeneous contents: enzymes, zona binding proteins, structural proteins (matrix) and yet to be chemically characterized crystalloids. The plasma and acrosomal membranes present stabilized ordered domains, whereas glycoprotein-free areas appear during capacitation and before fusion. Exocytosis, induced by the cumulus oophorus and/or the zona pellucida, may generally start proximally and progress anteriorly, resulting in the detachment of a hybrid membrane shroud, whose entity is probably maintained by the bound matrix. Immediately released soluble enzymes must be active during the first interactions of the gametes, whereas other lysins, bound to the matrix or stored as proenzymes, are only progressively released. Zona binding is probably achieved via the shroud and/or the IAM (depending on species). Penetration along an incurved slit through the stratified zona is allowed by the rigid and denuded head tip and flagellar hyperactivity, and assisted by the local proteolytic activity of proteasomes bound to the IAM, the unique essential zona lysin system.

  18. Comparative ultracytochemical study of the acrosome in four different Veneroida species from the Turkish coast.

    Science.gov (United States)

    Erkan, M; Sousa, M; Baldaia, L

    2002-04-01

    Cytoplasmic acidic phosphoproteins and complex polysaccharides were stained with ammoniacal silver nitrate-formalin and phosphotungstic acid-chromic acid, respectively. In Cerastoderma glaucum (Cardiacea), acrosomal vesicle contents are differentiated into an apical intermediate-dense component and a basal dense region. PTA stained the apical component and silver stained the basal region and the apex of the acrosome. In Spisula subtruncata (Mactracea) the acrosome showed a PTA-stained apical component and a silver-positive basal dense region. In the Veneracea, Chamelea gallina and Pitar rudis show a tripartite acrosomal vesicle, with apical light, outer dense and inner intermediate-dense regions. In both species, the apical and inner components were stained by PTA, whereas silver stained all regions of the acrosomal vesicle in C. gallina and the apical and outer regions in P. rudis. In midpiece, only C. glaucum showed a positive silver reaction at the centriolar fossa.

  19. Effect of GABA on sperm acrosome reation in antisperm antibody positive patients

    Institute of Scientific and Technical Information of China (English)

    BianSL; ZhanW

    2002-01-01

    Objective:To investigate the effect of gamma-aminobutyric acid(GABA) on the rate of sperm acrosome reaction both in normal and antisperm antibody (AsAb) porsitive men.Methods:the sperm acrosome reaction was tested with triplestain technique in two groups of 18 men each.Results:(1)GABA increased the rate of sperm acrosome reaction both in normal and AsAb positive subjects(P<0.01);(2) GABA increased the Na+-K+-ATPase activity of sperm(P<0.01);(3)GABA increased the Ca2+-ATPase activity of sperm (P<0.05);(4)GABA decreased the production of MDA and oxygen free radicals of sperm.conclusion:GABA could regulate the rate of sperm acrosome reaction.

  20. Involvement of Complexin 2 in Docking, Locking and Unlocking of Different SNARE Complexes during Sperm Capacitation and Induced Acrosomal Exocytosis.

    NARCIS (Netherlands)

    Tsai, P.S.; Brewis, I.A.; van Maaren, J.; Gadella, B.M.

    2012-01-01

    Acrosomal exocytosis (AE) is an intracellular multipoint fusion reaction of the sperm plasma membrane (PM) with the outer acrosomal membrane (OAM). This unique exocytotic event enables the penetration of the sperm through the zona pellucida of the oocyte. We previously observed a stable docking of O

  1. Participación de enzimas translocasas en la reacción acrosomal del espermatozoide de conejo

    Directory of Open Access Journals (Sweden)

    Mayren-Mendoza, Félix de Jesús

    2012-01-01

    Full Text Available ResumenEste estudio se realizó con la finalidad de evaluar la participación de enzimas translocadoras de fosfolípidos en el proceso de reacción acrosomal, en espermatozoides de conejo obtenidos de la región caudal del epidídimo, utilizando la progesterona como inductor de reacción acrosomal y NEtilmaleimida como inhibidor de translocasas.SummaryThis study was conducted in order to evaluate the participation of translocating enzymes of phospholipids in the reaction process acrosomal in rabbit sperm obtained from the caudal region of epididymis, using progesterone as inducer of acrosome reaction and N-ethylmaleimide as an inhibitor of translocase.

  2. Cycle of the seminiferous epithelium of the bat Molossus molossus, characterized by tubular morphology and acrosomal development

    Institute of Scientific and Technical Information of China (English)

    Danielle Barbosa Morais; Tarcizio Antnio Rgo de Paula; Karine Moura de Freitas; Srgio Luis Pinto da Matta

    2012-01-01

    Objective:To describe the seminiferous epithelium cycle (SEC) by tubular morphology method, and the acrosomal development of individualizing spermatids, and to explore the distinction of the stages between two generations of spermatids. Methods: Testicular fragments were fixed in Karnovsky, embedded in glycol methacrylate and examined under light microscopy and transmission electron microscopy. Sections in 3 µm thickness were stained with toluidine blue for the characterization of the stages of the SEC by the tubular morphology method, or submitted to the PAS reaction for the visualization of the acrosomal formation. Additional details on the acrosomal formation were observed under transmission electron microscopy. Results:Through the eight stages described by tubular morphology method, 10 steps of acrosomal formation were observed in the spermatid development, called acrosomal steps. As the spermatids were produced in stage V of the tubular morphology method, it was at this stage from which began the steps of acrosomal development. Conclusions:We propose association of the acrosomal steps for the first time, with the different stages by tubular morphology method. This method presents an alternative to the existent methods, allowing interspecific comparisons of the SEC, not only among different species of bats, but also among the other mammals.

  3. Normative Mediation of Reactions to Crowding

    Science.gov (United States)

    Karlin, Robert A.; And Others

    1976-01-01

    This study manipulated norms governing interaction levels in crowded groups of women. Results indicated norms influenced reactions to crowding as predicted. Women reacted most positively when interaction levels were high and most negatively when interaction levels were low. (Author)

  4. Mechanochemical Lignin-Mediated Strecker Reaction

    Directory of Open Access Journals (Sweden)

    Saumya Dabral

    2017-01-01

    Full Text Available A mechanochemical Strecker reaction involving a wide range of aldehydes (aromatic, heteroaromatic and aliphatic, amines, and KCN afforded a library of α-aminonitriles upon mechanical activation. This multicomponent process was efficiently activated by lignocellulosic biomass as additives. Particularly, commercially available Kraft lignin was found to be the best activator for the addition of cyanide to the in situ formed imines. A comparative study of the 31P-NMR (Nuclear Magnetic Resonance along with IR (Infrared data analysis for the Kraft lignin and methylated Kraft lignin samples ascertained the importance of the free hydroxyl groups in the activation of the mechanochemical reaction. The solvent-free mechanochemical Strecker reaction was then coupled with a lactamization process leading to the formation of the N-benzylphthalimide (5a and the isoindolinone derivative 6a.

  5. Evaluation on Sperm Acrosome Integrity of Infertile Men with Varicocele

    Institute of Scientific and Technical Information of China (English)

    P.Tzvetkova; Wei-jie ZHU; Jing LI; D.Tzvetkov

    2007-01-01

    Objective To determine the sperm acrosome integrity of samples from infertile men with varicocele.Methods Forty-nine infertile men with varicocele were divided into three groups according to the grade of varicocele. Group A (grade Ⅰ), B (grade Ⅱ), and C (grade Ⅲ) consisted of 15, 18, and 16 cases, respectively. Besides, 15 semen samples from normospermic donors were used as the control. The acrosome integrity of sperm was examined with fluorescein-labeled Pisum sativum agglutinin. Acrosomal ultrastructure was observed with transmission electron microscopy.Results In three varicocele groups, most samples had high sperm abnormal morphology rates. There were significant differences in acrosome integrity rates between each varicocele group and the control (P<0.01). Group C had the lowest acrosome integrity rate among the three groups. Ultrastructural observation showed that acrosome malformations revealed acrosomal membranes defects, swelling, hypoplasia, and dissolution of the matrix.Conclusions Infertile men with varicocele had low level of acrosome integrity. Severe varicocele for infertile men might be associated with severe acrosomal defects. Evaluating sperm acrosome should aid the understanding of the sperm structural state and benefit the treatment for infertile men.

  6. Evidence that nitric oxide synthase is involved in progesterone-induced acrosomal exocytosis in mouse spermatozoa.

    Science.gov (United States)

    Herrero, M B; Viggiano, J M; Pérez Martínez, S; de Gimeno, M F

    1997-01-01

    In a recent work, we detected nitric oxide synthase (NO synthase) in the acrosome and tail of mouse and human spermatozoa by an immunofluorescence technique. Also, NO-synthase inhibitors added during sperm capacitation in vitro reduced the percentage of oocytes fertilized in vitro, suggesting a role for NO synthase in sperm function. Therefore, in the present study the effect of three NO-synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME), NG-nitro-D-arginine methyl ester (D-NAME) and L-NG-nitro-arginine (NO2-arg), and of a nitric oxide donor, spermine-NONOate, on the progesterone-induced acrosome reaction of mouse sperm was examined. NO-synthase inhibitors were added at 0, 60 or 90 min during capacitation; at 120 min, mouse epididymal spermatozoa were exposed to 15 microM progesterone for another 15 min. In another set of experiments, different concentrations of spermine-NONOate were added to capacitated spermatozoa for 15 min; in these experiments, progesterone was not included. NO2-arg and L-NAME blocked progesterone-induced exocytosis regardless of the time at which these inhibitors were added. Moreover, D-NAME did not inhibit exocytosis. In contrast, spermine-NONOate stimulated the acrosomal exocytosis in vitro directly. These results provide evidence that mouse sperm NO synthase participates in the progesterone-induced acrosome reaction in vitro and that nitric oxide induces this event.

  7. Reaction mechanisms of ruthenium tetroxide mediated oxidations of organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Froehaug, Astrid Elisabeth

    1995-12-31

    This thesis reports a study of the mechanism of ruthenium tetroxide mediated oxidations of saturated hydrocarbons, ethers, alkenes and alcohols. Several methods were used. The RuO{sub 4}-mediated oxidations of adamantane and cis-decalin were studied in CCl{sub 4}-CH{sub 3}CN-H{sub 2}O and in acetone-water. The rate of reaction was found to be moderately influenced by the polarity of the solvent. Solvent properties other than the polarity were also found to influence the reaction rates. From the oxidations of adamantane and adamantane-1,3,5,7-d{sub 4} two primary kinetic deuterium isotope effects were found. These were comparable with the deuterium isotope effects found for the analogous oxidations of cis-decalin and cis-decalin-d{sub 18}. The results seem to exclude both a one step hydride abstraction reaction mechanism and a one step concerted mechanism, as well as a scheme where two such mechanisms compete. The observations may be explained by a two step reaction mechanism consisting of a pre-equilibrium with formation of a substrate-RuO{sub 4} complex followed by a concerted rate determining reaction. The RuO{sub 4}-mediated oxidation of ethers was of kinetic second order with a small enthalpy of activation and a large negative entropy of activation. Oxidation of cyclopropylmethyl methyl ether gave methyl cyclopropanecarboxylate, no rearranged products were observed. On RuO{sub 4} oxidations in CCl{sub 4} with NaIO{sub 4} as stoichiometric oxidant, no chlorinated products were observed. Several observations not in agreement with a hydride or a hydrogen abstraction mechanism may be explained by assuming that the reaction proceeds by either a concerted reaction or by a reversible oxidative addition of the ether to RuO{sub 4} followed by a slow concerted step. 228 refs., 9 figs., 27 tabs.

  8. A Note on the Kinetics of Diffusion-mediated Reactions

    CERN Document Server

    Naqvi, K Razi

    2014-01-01

    The prevalent scheme of a diffusion-mediated bimolecular reaction $A+B\\rightarrow P$ is an adaptation of that proposed by Briggs and Haldane for enzyme action [{\\em Biochem J.\\/}, 19:338--339, 1925]. The purpose of this Note is to explain, {\\em by using an argument involving no mathematics\\/}, why the breakup of the encounter complex cannot be described, except in special circumstances, in terms of a first-order process $\\{AB\\}\\rightarrow A+B$. Briefly, such a description neglects the occurrence of re-encounters, which lie at the heart of Noyes's theory of diffusion-mediated reactions. The relation $k=\\alpha k_{\\mbox{\\scriptsize e}}$ becomes valid only when $\\alpha$ (the reaction probability per encounter) is very much smaller than unity (activation-controlled reactions), or when $\\beta$ (the re-encounter probability) is negligible (as happens in a gas-phase reaction). References to some works (by the author and his collaborators) which propound the correct approach for finding $k$ are also supplied.

  9. LVQ acrosome integrity assessment of boar sperm cells

    NARCIS (Netherlands)

    Petkov, Nicolai; Alegre, Enrique; Biehl, Michael; Sánchez, Lidia; Tavares, JMRS; Jorge, RMN

    2007-01-01

    We consider images of boar spermatozoa obtained with an optical phase-contrast microscope. Our goal is to automatically classify single sperm cells as acrosome-intact (class 1) or acrosome-reacted (class 2). Such classification is important for the estimation of the fertilization potential of a sper

  10. LVQ acrosome integrity assessment of boar sperm cells

    NARCIS (Netherlands)

    Petkov, Nicolai; Alegre, Enrique; Biehl, Michael; Sánchez, Lidia

    2006-01-01

    We consider images of boar spermatozoa obtained with an optical phase-contrast microscope. Our goal is to automatically classify single sperm cells as acrosome-intact (class 1) or acrosome-reacted (class 2). Such classification is important for the estimation of the fertilization potential of a sper

  11. Statistical properties of multistep enzyme-mediated reactions

    Energy Technology Data Exchange (ETDEWEB)

    Nemenman, Ilya [Los Alamos National Laboratory; Sinitsyn, Nikolai A [Los Alamos National Laboratory; De Ronde, Wiet H [AMOLF; Daniels, Bryan C [CORNELL; Mugler, Andrew [COLUMBIA

    2008-01-01

    Enzyme-mediated reactions may proceed through multiple intermediate conformational states before creating a final product molecule, and one often wishes to identify such intermediate structures from observations of the product creation. In this paper, we address this problem by solving the chemical master equations for various enzymatic reactions. We devise a perturbation theory analogous to that used in quantum mechanics that allows us to determine the first () and the second (variance) cumulants of the distribution of created product molecules as a function of the substrate concentration and the kinetic rates of the intermediate processes. The mean product flux V=d/dt (or 'dose-response' curve) and the Fano factor F=variance/ are both realistically measurable quantities, and while the mean flux can often appear the same for different reaction types, the Fano factor can be quite different. This suggests both qualitative and quantitative ways to discriminate between different reaction schemes, and we explore this possibility in the context of four sample multistep enzymatic reactions. We argue that measuring both the mean flux and the Fano factor can not only discriminate between reaction types, but can also provide some detailed information about the internal, unobserved kinetic rates, and this can be done without measuring single-molecule transition events.

  12. Green spermatozoa illuminate a 30-year-old model:sperm-egg adhesion involves intra-acrosomal proteins

    Institute of Scientific and Technical Information of China (English)

    Steve Tardif

    2011-01-01

    @@ Fertilisation in mammals involves many synchronized steps including spermegg adhesion.Prior to sperm-oolemma fusion,spermatozoa need to undergo the acrosome reaction (AR) or exocytosis.The universal belief,for many years,has been that the AR was initiated upon binding to the zona pellucida (ZP).As such acrosomal proteins were not thought to be involved in the primary contact with the ZP.These proteins were only suggested to be biologically relevant once the sperm were attached to the ZP and during subsequent events.However,recent data in the mouse have unequivocally demonstrated that spermatozoa can begin exocytosis before contact with ZP.1 It is a remarkable finding as not only will the interpretation of the interaction between sperm and cumulus cells need to be revised,but the processes of capacitation,vesiculation and exposure of acrosomal content need reexamination.

  13. Association between calcium ionophore A23187 induced acrosome reaction rate, total acrosin activity and semen analysis, the outcome of in vitro fertilization%钙离子载体A23187诱发的精子顶体反应率、顶体酶总活性与精液参数及体外受精结局的关系研究

    Institute of Scientific and Technical Information of China (English)

    郭小桥; 余波澜; 周华; 司沙沙; 曹定娅; 刘见桥; 孙筱放

    2013-01-01

    Objective To investigate the association between the calcium ionophore A23187 induced sperm acrosome reaction rate, total acrosin activity and semen parameters and the IVF outcome, and to compare the predictive value for the male fertility and the outcome of IVF between calcium ionophore A23187 induced sperm acrosome reaction rate and sperm total acrosoin activity. Methods Sperm acrosome reaction was induced by calcium ionophore A23187,while sperm acrosin activity was determined by the modified Kennedy method. In this study, 150 cycles of IVF-ET were included, which were divided into Normal semen Group (85 cycles), Teratospermia Group (44 cycles), Asthenozoospermia Group (6 cycles). Compare the association between the calcium ionophore A23187 induced sperm acrosome reaction rate, total acrosin activity and normal morphology sperm percentage, concentration, activity in the 150 cycles and subgroups. Analyze the difference of the sperm acrosome reaction rate and total acrosin activity in Pregnancy Group and Non-pregnancy Group. Use the Receiver Operating Characteristic curve to make out the threshold of the sperm acrosome reaction rate and total acrosin activity for predicting the IVF pregnancy outcomes. Results In this 150 samples, there are no statistically significant differences between sperm acrosome reaction rate and sperm concentration, progressive velocity rate, the percentage of normal sperm morphology, fertility rate, and their related coefficient are respectively as follow:0.120, 0.018, 0.084, 0.054(P>0.05). But the negative correlation is statistically significant different between sperm acrosome reaction rate and teratozoospermia index(r=-0.183, P=0.025). There are significant correlations between sperm acrosin activity and sperm concentration(r=0.172, P0.05) and fertility rate(r=0.039, P>0.05). There are no statistically significant differences between sperm acrosome rate and fertility rate in Normal semen Group(r=-0.039, P>0.05), Teratospermia Group

  14. Removal of triclosan via peroxidases-mediated reactions in water: Reaction kinetics, products and detoxification.

    Science.gov (United States)

    Li, Jianhua; Peng, Jianbiao; Zhang, Ya; Ji, Yuefei; Shi, Huanhuan; Mao, Liang; Gao, Shixiang

    2016-06-05

    This study investigated and compared reaction kinetics, product characterization, and toxicity variation of triclosan (TCS) removal mediated by soybean peroxidase (SBP), a recognized potential peroxidase for removing phenolic pollutants, and the commonly used horseradish peroxidase (HRP) with the goal of assessing the technical feasibility of SBP-catalyzed removal of TCS. Reaction conditions such as pH, H2O2 concentration and enzyme dosage were found to have a strong influence on the removal efficiency of TCS. SBP can retain its catalytic ability to remove TCS over broad ranges of pH and H2O2 concentration, while the optimal pH and H2O2 concentration were 7.0 and 8μM, respectively. 98% TCS was removed with only 0.1UmL(-1) SBP in 30min reaction time, while an HRP dose of 0.3UmL(-1) was required to achieve the similar conversion. The catalytic performance of SBP towards TCS was more efficient than that of HRP, which can be explained by catalytic rate constant (KCAT) and catalytic efficiency (KCAT/KM) for the two enzymes. MS analysis in combination with quantum chemistry computation showed that the polymerization products were generated via CC and CO coupling pathways. The polymers were proved to be nontoxic through growth inhibition of green alga (Scenedesmus obliquus). Taking into consideration of the enzymatic treatment cost, SBP may be a better alternative to HRP upon the removal and detoxification of TCS in water/wastewater treatment.

  15. Peritoneal fluid modulates the sperm acrosomal exocytosis induced by N-acetylglucosaminyl neoglycoprotein

    Directory of Open Access Journals (Sweden)

    Passos E.P.

    1999-01-01

    Full Text Available The effect of peritoneal fluid (PF on the human sperm acrosome reaction (AR was tested. Sperm was pre-incubated with PF and the AR was induced by calcium ionophore A23187 and a neoglycoprotein bearing N-acetylglycosamine residues (NGP. The AR induced by calcium ionophore was inhibited 40% by PF from controls (PFc and 50% by PF from the endometriosis (PFe group, but not by PF from infertile patients without endometriosis (PFi. No significant differences were found in the spontaneous AR. When the AR was induced by NGP, pre-incubation with PFc reduced (60% the percentage of AR, while PFe and PFi caused no significant differences. The average rates of acrosome reactions obtained in control, NGP- and ionophore-treated sperm showed that NGP-induced exocytosis differed significantly between the PFc (11% and PFe/PFi groups (17%, and the ionophore-induced AR was higher for PFi (33% than PFc/PFe (25%. The incidence of the NGP-induced AR was reduced in the first hour of pre-incubation with PFc and remained nearly constant throughout 4 h of incubation. The present data indicate that PF possesses a protective factor which prevents premature AR.

  16. Nanovid microscopy for assessing sperm membrane changes induced by in vitro capacitating and acrosomal reacting procedures.

    Science.gov (United States)

    Degelos, S D; Wilson, M P; Chandler, J E

    1994-01-01

    This study was to verify the usefulness of Nanovid microscopy techniques for evaluating induced modifications in bovine spermatozoal membranes. Frozen thawed bovine sperm were labeled with 20-nm colloidal gold particles bound to concanavalin A (ConA) or heparin ligands. Sperm membrane changes were induced in vitro by capacitating and acrosome-reacting procedures. Capacitation was induced by incubation with 10 micrograms/ml of heparin for 4 hours at 37 degrees C, 5% CO2, and high humidity. Membrane changes associated with the acrosome reaction were induced by addition of lysophosphatidylcholine (100 micrograms/ml) and incubation for 15 minutes at 37 degrees C, 5% CO2, and high humidity. Gray intensity (black = 0; white = 255) of sperm (ONCELL) and background (OFFCELL) were evaluated with computer-enhanced videomicroscopy with either differential interference contrast (DIC) or Nanovid optics. A high gold concentration on a membrane region produced blacker video pictures with Nanovid microscopy. Gray intensity of video pictures of a region with little or no gold would have a gray intensity equal to or greater than that of the background, that is, toward white. Weighted least squares methods were used to analyze ONCELL data using OFFCELL as a covariate. In experiment 1, ONCELL intensities of cells labeled with ConA-gold complex were lower than those labeled with heparin-gold at the same treatment level. In experiment 2, ONCELL intensity decreased as the concentration of heparin-gold increased from 0 to 0.041 microgram/microliter heparin. ONCELL intensity significantly decreased after sperm were treated with the highest heparin-gold level and acrosome reacted.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Loss of Zona Pellucida Binding Proteins in the Acrosomal Matrix Disrupts Acrosome Biogenesis and Sperm Morphogenesis▿ †

    Science.gov (United States)

    Lin, Yi-Nan; Roy, Angshumoy; Yan, Wei; Burns, Kathleen H.; Matzuk, Martin M.

    2007-01-01

    Zona pellucida binding protein 1 (ZPBP1), a spermatid and spermatozoon protein that localizes to the acrosome, was originally identified in pigs and named for its binding to the oocyte zona pellucida. In an in silico search for germ cell-specific genes, Zpbp1 and its novel paralog, Zpbp2, were discovered and confirmed to be expressed only in the testes in both mice and humans. To study the in vivo functions of both ZPBP proteins, we disrupted Zpbp1 and Zpbp2 in mice. Males lacking ZPBP1 were sterile, with abnormal round-headed sperm morphology and no forward sperm motility. Ultrastructural studies demonstrated that absence of ZPBP1 prevents proper acrosome compaction, resulting in acrosome fragmentation and disruption of the Sertoli-spermatid junctions. Males null for ZPBP2 were subfertile, demonstrated aberrant acrosomal membrane invaginations, and produced dysmorphic sperm with reduced ability to penetrate zona pellucida. Molecular phylogenetic analysis of ZPBPs from amphibians, birds, and mammals suggests that these paralogous genes coevolved to play cooperative roles during spermiogenesis. Whereas ZPBP1 was discovered for an in vitro role in sperm-egg interactions, we have shown that both ZPBP proteins play an earlier structural role during spermiogenesis. PMID:17664285

  18. Polyfunctionalized pyrrolidines by Ugi multicomponent reaction followed by palladium-mediated SN2' cyclizations.

    Science.gov (United States)

    Banfi, Luca; Basso, Andrea; Cerulli, Valentina; Guanti, Giuseppe; Riva, Renata

    2008-02-15

    A 4-component Ugi reaction with a suitable isocyanide, followed by a novel secondary transformation involving a Pd(II)-mediated (R5 = H) or a Pd(0)-mediated (R5 = CO2Me) SN2' cyclization to give highly functionalized N-acyl-2-vinylpyrrolidines, is reported. The overall yields are usually good and in most cases the Pd(0)-catalyzed reaction gave the final product in almost quantitative yield.

  19. Multicomponent asymmetric reactions mediated by proline lithium salt

    DEFF Research Database (Denmark)

    Renzi, Polyssena; Overgaard, Jacob; Bella, Marco

    2010-01-01

    The multicomponent reaction between proline lithium salt, 2-cyclohexen-1-one and aliphatic aldehydes affords the 4- alkylidene-2-cyclohexen-1-ones, which are interesting fragrances, and bicyclic amino acids that bear four additional stereocenters, obtained as single stereoisomer....

  20. Mediated priming in the lexical decision task : Evidence from event-related potentials and reaction time

    NARCIS (Netherlands)

    Chwilla, DJ; Kolk, HHJ; Mulder, G

    2000-01-01

    Mediated priming (e.g., from LION to STRIPES vis TIGER) is predicted by spreading activation models hut only by some integration model. The goal of the present research was to localize mediated priming by assessing two-step priming effects on N400 and reaction times (RT). We propose that the N400 pr

  1. Solvent-free microwave-mediated Michael addition reactions

    Indian Academy of Sciences (India)

    H Surya Prakash Rao; S Jothilingam

    2005-07-01

    Facile Michael addition of active methylene compounds to ,-unsaturated carbonyl compounds takes place on the surface of potassium carbonate under microwave irradiation. Further studies on microwave-mediated Robinson annulations reveal a convenient and facile method for condensation of chalcone with methylene compounds to furnish cyclohexenones.

  2. Synthesis of novel photochromic pyrans via palladium-mediated reactions

    NARCIS (Netherlands)

    Böttcher, Christoph; Zeyat, Gehad; Ahmed, Saleh A.; Irran, Elisabeth; Cordes, Thorben; Elsner, Cord; Zinth, Wolfgang; Rueck-Braun, Karola

    2009-01-01

    Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from a bromo-substituted naphthopyran and benzopyrans. A novel photoswitchable benzopyran-based ω-amino acid for Fmoc-based soli

  3. Inflammatory Mediators of Leprosy Reactional Episodes and Dental Infections: A Systematic Review

    Science.gov (United States)

    Cortela, D. C. B.; de Souza Junior, A. L.; Virmond, M. C. L.; Ignotti, E.

    2015-01-01

    Reactional episodes in leprosy are a result of complex interactions between the immune system, Mycobacterium leprae, and predisposing factors, including dental infections. To determine the main inflammatory mediators in the immunopathological process of dental infections and leprosy reactions, we conducted a systematic review of primary literature published between 1996 and 2013. A three-stage literature search was performed (Stage I, “leprosy reactions” and “inflammatory mediators”; Stage II, “dental infections” and “inflammatory mediators”; and Stage III, “leprosy reactions,” “dental infections,” and “inflammatory mediators”). Of the 911 eligible publications, 10 were selected in Stage I, 68 in Stage II, and 1 in Stage III. Of the 27 studied inflammatory mediators, the main proinflammatory mediators were IL-6, IFN-γ, TNF-α, IL-1β, and IL-17; the main anti-inflammatory mediators were IL-10 and IL-4. Serum IL-6 and TNF-α concentrations were significant during periodontal and reactional lesion evolution; IFN-γ and IL-1β were associated with types 1 and 2 reactions and chronic periodontal disease. The proinflammatory mediators in dental infections and leprosy reactions, especially IL-6 and TNF-α, were similar across studies, regardless of the laboratory technique and sample type. IFN-γ and IL-1β were significant for leprosy reactions and periodontal diseases. This pattern was maintained in serum. PMID:26339136

  4. Polymerase chain reaction-mediated DNA fingerprinting for epidemiological studies on Campylobacter spp

    NARCIS (Netherlands)

    Giesendorf, B A; Goossens, H; Niesters, H G; Van Belkum, A; Koeken, A; Endtz, H P; Stegeman, H; Quint, W G

    1994-01-01

    The applicability of polymerase chain reaction (PCR)-mediated DNA typing, with primers complementary to dispersed repetitive DNA sequences and arbitrarily chosen DNA motifs, to study the epidemiology of campylobacter infection was evaluated. With a single PCR reaction and simple gel electrophoresis,

  5. Towards a General Understanding of Carbonyl-Stabilised Ammonium Ylide-Mediated Epoxidation Reactions.

    Science.gov (United States)

    Novacek, Johanna; Roiser, Lukas; Zielke, Katharina; Robiette, Raphaël; Waser, Mario

    2016-08-01

    The key factors for carbonyl-stabilised ammonium ylide-mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine-based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions.

  6. Decolorization and degradation of dyes with mediated fenton reaction.

    Science.gov (United States)

    Goodell, Barry; Qian, Yuhui; Jellison, Jody; Richard, Mike

    2004-01-01

    A mediated Fenton system has been evaluated for decolorization of several types of dyes. The result shows that the Fenton system with a dihydroxybenzoic acid (DHBA) chelator-mediator effectively reduced the color of a diluted solution of Carta Yellow RW liquid, Carta Yellow G liquid, and Cartasol Red 2GF liquid dye to a colorless level after 90 minutes of treatment with 100 microM iron II (Fe[II]), 100 microM DHBA, and 10 mM hydrogen peroxide (H2O2) at room temperature. Our results show that compared to a neat Fenton process, the mediated Fenton decolorization process increased the production, and therefore the effective longevity, of hydroxyl radical (OH) species to increase the decolorization efficiency. Our results suggest that application of this system would also result in an increase in dissolved oxygen (DO) in solution, which in turn would result in reduction of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC).

  7. Notch-mediated lateral inhibition regulates proneural wave propagation when combined with EGF-mediated reaction diffusion.

    Science.gov (United States)

    Sato, Makoto; Yasugi, Tetsuo; Minami, Yoshiaki; Miura, Takashi; Nagayama, Masaharu

    2016-08-30

    Notch-mediated lateral inhibition regulates binary cell fate choice, resulting in salt and pepper patterns during various developmental processes. However, how Notch signaling behaves in combination with other signaling systems remains elusive. The wave of differentiation in the Drosophila visual center or "proneural wave" accompanies Notch activity that is propagated without the formation of a salt and pepper pattern, implying that Notch does not form a feedback loop of lateral inhibition during this process. However, mathematical modeling and genetic analysis clearly showed that Notch-mediated lateral inhibition is implemented within the proneural wave. Because partial reduction in EGF signaling causes the formation of the salt and pepper pattern, it is most likely that EGF diffusion cancels salt and pepper pattern formation in silico and in vivo. Moreover, the combination of Notch-mediated lateral inhibition and EGF-mediated reaction diffusion enables a function of Notch signaling that regulates propagation of the wave of differentiation.

  8. Synthesis of novel photochromic pyrans via palladium-mediated reactions

    Directory of Open Access Journals (Sweden)

    Christoph Böttcher

    2009-05-01

    Full Text Available Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based ω-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-substituted benzopyran 5a was investigated by time-resolved absorption spectroscopy in the picosecond time domain.

  9. Alkali metal mediated C-C bond coupling reaction.

    Science.gov (United States)

    Tachikawa, Hiroto

    2015-02-14

    Metal catalyzed carbon-carbon (C-C) bond formation is one of the important reactions in pharmacy and in organic chemistry. In the present study, the electron and hole capture dynamics of a lithium-benzene sandwich complex, expressed by Li(Bz)2, have been investigated by means of direct ab-initio molecular dynamics method. Following the electron capture of Li(Bz)2, the structure of [Li(Bz)2](-) was drastically changed: Bz-Bz parallel form was rapidly fluctuated as a function of time, and a new C-C single bond was formed in the C1-C1' position of Bz-Bz interaction system. In the hole capture, the intermolecular vibration between Bz-Bz rings was only enhanced. The mechanism of C-C bond formation in the electron capture was discussed on the basis of theoretical results.

  10. Inflammatory Mediators of Leprosy Reactional Episodes and Dental Infections: A Systematic Review

    OpenAIRE

    Cortela, D. C. B.; de Souza Junior, A. L.; M. C. L. Virmond; E. Ignotti

    2015-01-01

    Reactional episodes in leprosy are a result of complex interactions between the immune system, Mycobacterium leprae, and predisposing factors, including dental infections. To determine the main inflammatory mediators in the immunopathological process of dental infections and leprosy reactions, we conducted a systematic review of primary literature published between 1996 and 2013. A three-stage literature search was performed (Stage I, “leprosy reactions” and “inflammatory mediators”; Stage II...

  11. Coupling Reaction of Carbonyl Compounds Mediated by Gallium Metal in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    汪志勇; 袁仕祯; 查正根; 张祖德

    2003-01-01

    A simple and effective pinacol coupling of various aromatic aldehydes mediated by gallium in good yields has been carried out. The reaction is highly effective in water in the prurience of KOH or HCl and was strongly affected by the steric environ-ment surrounding the carbonyl group. Aliphaflc aldehydes, ke-tones and aromatic ketones appear inert under the same reac-tion conditions.

  12. Phosphoric Acid-Mediated Synthesis of Vinyl Sulfones through Decarboxylative Coupling Reactions of Sodium Sulfinates with Phenylpropiolic Acids.

    Science.gov (United States)

    Rong, Guangwei; Mao, Jincheng; Yan, Hong; Zheng, Yang; Zhang, Guoqi

    2015-08-07

    A novel phosphoric acid -mediated synthesis of vinyl sulfones through decarboxylative coupling reactions of sodium sulfinates with phenylpropiolic acids is described. This transformation is efficient and environmentally friendly.

  13. Eicosanoids mediate nodulation reactions to a Mollicute bacterium in larvae of the blowfly, Chrysomya megacephala

    Science.gov (United States)

    Nodulation is the temporally and quantitatively most important cellular defense response to bacterial, fungal and some viral infections in insects. We tested the hypothesis that prostaglandins and other eicosanoids are responsible for mediating nodulation reactions to bacterial infection in larvae o...

  14. Site-specific N-terminal labeling of proteins using sortase-mediated reactions

    NARCIS (Netherlands)

    Theile, Christopher S.; Witte, Martin D.; Blom, Annet E. M.; Kundrat, Lenka; Ploegh, Hidde L.; Guimaraes, Carla P.

    2013-01-01

    This protocol describes the use of sortase-mediated reactions to label the N terminus of any given protein of interest. The sortase recognition sequence, LPXTG (for Streptococcus aureus sortase A) or LPXTA (for Staphylococcus pyogenes sortase A), can be appended to a variety of probes such as fluoro

  15. Automatic classification of the acrosome status of boar spermatozoa using digital image processing and LVQ

    NARCIS (Netherlands)

    Alegre, Enrique; Biehl, Michael; Petkov, Nicolai; Sanchez, Lidia

    2008-01-01

    We consider images of boar spermatozoa obtained with ail optical phase-contrast microscope. Our goal is to automatically classify single sperm cells as acrosome-intact (class 1) or acrosome-damaged (class 2). Such classification is important for the estimation of the fertilization potential of a spe

  16. Effect of disodium cromoglycate on mast cell-mediated immediate-type allergic reactions.

    Science.gov (United States)

    Shin, Hye-Young; Kim, Jung-Sook; An, Nyeon-Hyoung; Park, Rae-Kil; Kim, Hyung-Min

    2004-04-23

    We investigated the effect of disodium cromoglycate (DSCG) on mast cell-mediated immediate-type hypersensitivity. DSCG inhibited systemic allergic reaction induced by compound 48/80 dose-dependently. Passive cutaneous anaphylaxis was inhibited by 71.6% by oral administration of DSCG (1 g/kg). When DSCG was pretreated at concentration rang from 0.01-1000 g/kg, the serum histamine levels were reduced in a dose dependent manner. DSCG also significantly inhibited histamine release from rat peritoneal mast cell (RPMC) by compound 48/80. We confirmed that DSCG inhibited compound 48/80-induced degranulation of RPMC by alcian blue/nuclear fast red staining. In addition, DSCG showed a significant inhibitory effect on anti-dinitrophenyl IgE-mediated tumor necrosis factor-alpha production. These results indicate that DSCG inhibits mast cell-mediated immediate-type allergic reaction.

  17. Suicide Disclosure in Suicide Attempt Survivors: Does Family Reaction Moderate or Mediate Disclosure's Effect on Depression?

    Science.gov (United States)

    Frey, Laura M; Hans, Jason D; Cerel, Julie

    2016-02-01

    Existing literature has found a link between disclosure of a stigmatized identity and improved mental health; however, research on the impact of suicide disclosure to family members is scarce. Suicide attempt survivors (n = 74) in the United States were examined to assess whether family reaction moderates or mediates the relationship between suicide disclosure and subsequent depression symptoms. Family reaction did not moderate but did mediate the relationship between disclosure and depression symptoms while controlling for time since most recent attempt. Higher rates of disclosure predicted more positive family reactions, which in turn predicted less severe depression symptoms. Findings indicate that family members can play an essential role in the recovery process after an attempt occurs, which has important implications for both researchers and clinicians who seek to decrease stigma for attempt survivors while simultaneously decreasing the likelihood of future attempts.

  18. THE ADDITION OF CAFFEINE IN EARLE’S BALANCED SALT SOLUTION MEDIA WITH WASHING UP METHOD INCREASE MEMBRANE INTEGRITY AND ACROSOMAL SPERM

    Directory of Open Access Journals (Sweden)

    B. K. Satriyasa

    2014-12-01

    Full Text Available Background: caffeine, a methylxanthine derivate, appears to inhibit phosphodiesterase, thereby inhibiting the break down of cAMP and increasing its concentration inside cell. This study aims to assess the effect of caffeine addition in Earles’s Balanced Salt Solution (EBSS on the increase in membrane integrity and acrosome reaction of spermatozoa using swim up method. Methods: This study was carried out at the Clinic of Sexology and Andrology, Sanglah Public Hospital at Denpasar Bali-Indonesia. This study was an experimental study using the design of pre and post test paired control group design. The samples were sperm specimens of eighteen infertile couple male or volunteers who were infertile with age ranged between 20-40 years old. The samples   were divided into two groups: treatment group (caffeine + EBSS and control group (EBSS. The data were analysed statistically by normality test (Kolmogorov - Smirnov Goodness of Fit Test, Homogeneity test, and Paired Student’s t test.  Results: The results showed that the caffeine addition in EBSS medium could increase significantly (p<0.05.  The integrity of the sperm membrane obtained were from 81.30 % to 86.60 % and acrosomal reaction from 82.60% to 89.60% evaluated by hypo-osmotic swelling test (HOS. The conclusion of this study is that addition of caffeine in EBSS medium increases significantly membrane integrity and acrosomal reaction of the human sperm.

  19. Horseradish Peroxidase-Mediated, Iodide-Catalyzed Cascade Reaction for Plasmonic Immunoassays.

    Science.gov (United States)

    Xianyu, Yunlei; Chen, Yiping; Jiang, Xingyu

    2015-11-01

    This report outlines an enzymatic cascade reaction for signal transduction and amplification for plasmonic immunoassays by using horseradish peroxidase (HRP)-mediated aggregation of gold nanoparticles (AuNPs). HRP-catalyzed oxidation of iodide and iodide-catalyzed oxidation of cysteine is employed to modulate the plasmonic signals of AuNPs. It agrees well with the current immunoassay platforms and allows naked-eye readout with enhanced sensitivity, which holds great promise for applications in resource-constrained settings.

  20. Single Photon Initiated Decomposition Rearrangement Reactions (spidrr) of Organic Molecules Mediated by the Ni+ Cation

    Science.gov (United States)

    Bellert, Darrin; Mansell, Adam; Theis, Zachary; Gutierrez, Michael

    2016-06-01

    The Bellert group at Baylor University has developed a novel method for performing single photon initiated decomposition rearrangement reactions (SPIDRR) of organic molecules mediated by a transition metal cation. The advantage that SPIDRR affords is the direct measurement of first order microcanonical rate constants, k(E), determined at resolved internal energies. Furthermore, the SPIDRR technique measures kinetic details of exothermic reactions where product production is limited only by submerged activation barriers (kinetic barriers that are at energies below the separated reactant limit). Thus, such reactions approach unit efficiency, are thermodynamically driven, and are of greater relevance to catalytic research. Direct measurements of k(E) values extend to isotopically labelled species that provide direct measurement of the kinetic isotope effect (KIE), furnishing unique insight into the mechanistic details of a reaction. This talk presents results from the visible photon initiated, Ni+ induced decarbonylation reaction of propionaldehyde. Here a rather unique energy dependent behavior of the measured rate constants was observed and attributed to a dynamic competition between parallel reaction coordinates available to the photo-excited precursor. RRKM calculations in concert with high level DFT is used to support and further experimental results.

  1. Inhibitory effects of atractylone on mast cell-mediated allergic reactions.

    Science.gov (United States)

    Han, Na-Ra; Moon, Phil-Dong; Nam, Sun-Young; Ryu, Ka-Jung; Yoou, Myoung-Schook; Choi, Jung-Hye; Hwang, Sung-Yeoun; Kim, Hyung-Min; Jeong, Hyun-Ja

    2016-10-25

    This study investigated a salutary effect of atractylone (Atr) which is an active constituent of Pyeongwee-San (KMP6) on mast cell-mediated allergic reactions. Our previous report indicated that KMP6 regulated allergic reactions. Thus, this study sought to determine the potential of Atr in vitro models, compound 48/80-stimulated rat peritoneal mast cells (RPMCs), phorbol 12-myristate 13-acetate (PMA) plus A23187-stimulated human mast cell line (HMC-1) cells, and stem cell factor (SCF)-stimulated RPMCs as well as in vivo models, IgE-mediated passive cutaneous anaphylaxis (PCA), compound 48/80-induced systemic anaphylaxis, and compound 48/80-induced ear swelling. The results showed that Atr inhibited compound 48/80-induced RPMCs degranulation, intracellular calcium level, tryptase release, and histamine release. Atr inhibited the up-regulation of p56(lck) tyrosine kinase activity by compound 48/80. And Atr reduced tryptase and histamine releases from PMA plus A23187-stimulated HMC-1 cells. In addition, Atr decreased histidine decarboxylase activity and expression in the activated HMC-1 cells. Atr inhibited SCF-induced morphological alteration and filamentous actin formation in RPMCs. Atr improved IgE-induced PCA reaction by decreasing the levels of histamine, IgE, interleukin (IL)-4, IL-5, IL-6, vascular endothelial growth factor, and IL-13 in the serum of PCA-induced mice. Furthermore, Atr mitigated compound 48/80-induced systemic anaphylaxis and ear swelling. Taken together, these results of this study indicate that Atr regulates the degranulation of mast cell, proving its potential in the treatment of mast cell-mediated allergic reactions.

  2. Effect of caprine testicular extract on acrosome formation of spermatids of lead-injured mice

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    Hong-yan TIAN

    2012-11-01

    Full Text Available Objective  To investigate the effect of caprine testicular extract on the acrosomal formation of spermatids of lead-treated mice, and find a theoretical and experimental basis for further research on the effects of caprine testicular extract on the reproductive system. Methods The study was carried out on thirty male adult ICR mice, which were randomly assigned into control group, model group and treatment group (10 each. The testis-injury model was reproduced by intragastric administration of lead acetate (30mg/kg, 0.1ml/10g. Animals in treatment group received intragastric administration of lead acetate and intraabdominal injection of 0.5ml caprine testicular extract at the same time for 21days, and the mice in control group received the same amount of distilled water by intragastric administration and 0.5ml distilled water by intraabdominal injection. By the end of the experimental period, the mice were sacrificed. The testes were fixed by cardiac perfusion and processed for light microscopic examination. The acrosomal formation in round spermatids was observed by PAS staining. Results  Compared with the control group, the acrosomal formation in model group was blocked. Acrosomal vesicle was incomplete, the membrane was shrunken, rough and fuzzy. The acrosomal formation in treatment group was similar to that of the control group. The structure of the acrosomal vesicle was complete and the membrane was smooth. Conclusion  Administration of caprine testicular extract may protect the acrosomal formation of spermatids from lead poisoning, and the normal structure and function of the acrosome are preserved. Thus, indepth study of the effects of caprine testicular extract may contribute to the treatment of male infertility caused by heavy metal-induced testicular damage, and offer an effective protective measure for the lead-exposed males.

  3. Molecular Cloning of Spergen-4, Encoding a Spermatogenic Cell-Specific Protein Associated with Sperm Flagella and the Acrosome Region in Rat Spermatozoa.

    Science.gov (United States)

    Howida, Ali; Salaheldeen, Elsaid; Iida, Hiroshi

    2016-04-01

    We used a differential display in combination with complementary DNA (cDNA) cloning approach to isolate a novel rat gene LOC690919 with an open reading frame of 1227-length nucleotides encoding a protein of 409 amino acids. This gene was designated as Spergen-4 (a spermatogenic cell-specific gene-4). Spergen-4 mRNA was highly expressed in testis, and its expression was detected in rat testis starting at three weeks of postnatal development and persisting up to adulthood. Mouse and human orthologs, which lack N-terminal 77 amino acid residues of rat Spegen-4, were found in the database. Immunofluorescence microscopy and immunoblot analysis demonstrated that Spergen-4 was not expressed in spermatogonia, spermatocytes, and round spermatids, but was restrictedly detected at sperm head, cytoplasm, and developing flagella of elongated spermatids in rat testis. In mature spermatozoa, Spergen-4 was detected at the acrosome region as well as the principal piece of flagella. Spergen-4 immunosignal disappeared from sperm heads on acrosome reaction induced by progesterone. These data suggest that Spergen-4 integrated into elongated spermatids during spermiogenesis serves as a constituent for acrosome region and flagella of rat spermatozoa.

  4. Immunoglobulin E-mediated hypersensitivity reaction after intraperitoneal administration of vancomycin

    Directory of Open Access Journals (Sweden)

    Mun-Ju Hwang

    2015-03-01

    Full Text Available Intraperitoneal (IP vancomycin is widely used to treat Gram-positive peritonitis associated with peritoneal dialysis. There have been two cases of red man syndrome (RMS, a vancomycin-specific nonimmunologic reaction, associated with IP vancomycin. However, immune-mediated hypersensitivity reaction to IP vancomycin has not yet been reported. A 49 year old woman on continuous ambulatory peritoneal dialysis developed her first peritonitis episode. The patient was treated with IP vancomycin once/wk for 4 weeks. She experienced mild itching and flushing throughout her body for 1 day after the second treatment. Whenever vancomycin was administered, generalized urticaria and a prickling sensation developed, and the intensity increased gradually; however, these symptoms improved after vancomycin was discontinued. An allergic skin test was performed 6 weeks after the previous urticarial episode, and an intradermal skin test revealed a positive response to vancomycin. To our knowledge, this is the first case report of immunoglobulin E-mediated hypersensitivity reaction to IP vancomycin administration.

  5. Proton mediated control of biochemical reactions with bioelectronic pH modulation

    Science.gov (United States)

    Deng, Yingxin; Miyake, Takeo; Keene, Scott; Josberger, Erik E.; Rolandi, Marco

    2016-04-01

    In Nature, protons (H+) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H+ channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H+ currents and H+ concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H+ between PdHx contacts and solution. The present transducer records bistable pH modulation from an “enzymatic flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. The transducer also controls bioluminescence from firefly luciferase by affecting solution pH.

  6. Assessing the reaction conditions to mediate the milkfat-soybean oil enzymatic interesterification

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    Ariela Veloso de Paula

    Full Text Available Summary A food grade lipase from Rhizopus oryzae immobilized on a hybrid polysiloxane-polyvinyl alcohol matrix (SiO2-PVA was used as the biocatalyst to mediate the interesterification reactions of a blend containing 65% milkfat and 35% soybean oil. All the reactions occurred in an inert nitrogen atmosphere in cylindrical glass reactors (80 mL with 40 g of the milkfat-soybean oil blend. The influence of the following variables was evaluated: biocatalyst loading (250-1500 activity units per gram of blend, biocatalyst moisture content (5-20%, temperature (45-60 °C and incubation time (2-48 h. The reactions were monitored by determining the free fatty acid content, triacylglycerol (TAGs composition in carbon species, and the consistency of the interesterified (IE products. The reaction conditions were set based on the parameters that provided a high interesterification yield and good consistency of the final product within the ideal range (200 to 800 gf cm-2. Hence the best results were obtained using a biocatalyst loading of 500 U g-1 of blend with 10% moisture content at 45 °C for 4 h. Under these conditions the consistency of the interesterified product was 539.7 ± 38 gf cm-2. The results demonstrated the potential of the immobilized lipase to alter the TAGs profile of the milkfat-soybean oil blend, allowing for the production of structured lipids.

  7. Deformation-resembling microstructure created by fluid-mediated dissolution-precipitation reactions

    Science.gov (United States)

    Spruzeniece, Liene; Piazolo, Sandra; Maynard-Casely, Helen E.

    2017-01-01

    Deformation microstructures are widely used for reconstructing tectono-metamorphic events recorded in rocks. In crustal settings deformation is often accompanied and/or succeeded by fluid infiltration and dissolution-precipitation reactions. However, the microstructural consequences of dissolution-precipitation in minerals have not been investigated experimentally. Here we conducted experiments where KBr crystals were reacted with a saturated KCl-H2O fluid. The results show that reaction products, formed in the absence of deformation, inherit the general crystallographic orientation from their parents, but also display a development of new microstructures that are typical in deformed minerals, such as apparent bending of crystal lattices and new subgrain domains, separated by low-angle and, in some cases, high-angle boundaries. Our work suggests that fluid-mediated dissolution-precipitation reactions can lead to a development of potentially misleading microstructures. We propose a set of criteria that may help in distinguishing such microstructures from the ones that are created by crystal-plastic deformation.

  8. Coupling Solar Energy into Reactions: Materials Design for Surface Plasmon-Mediated Catalysis.

    Science.gov (United States)

    Long, Ran; Li, Yu; Song, Li; Xiong, Yujie

    2015-08-26

    Enabled by surface plasmons, noble metal nanostructures can interact with and harvest incident light. As such, they may serve as unique media to generate heat, supply energetic electrons, and provide strong local electromagnetic fields for chemical reactions through different mechanisms. This solar-to-chemical pathway provides a new approach to solar energy utilization, alternative to conventional semiconductor-based photocatalysis. To provide readers with a clear picture of this newly recognized process, this review presents coupling solar energy into chemical reactions through plasmonic nanostructures. It starts with a brief introduction of surface plasmons in metallic nanostructures, followed by a demonstration of tuning plasmonic features by tailoring their physical parameters. Owing to their tunable plasmonic properties, metallic materials offer a platform to trigger and drive chemical reactions at the nanoscale, as systematically overviewed in this article. The design rules for plasmonic materials for catalytic applications are further outlined based on existing examples. At the end of this article, the challenges and opportunities for further development of plasmonic-mediated catalysis toward energy and environmental applications are discussed.

  9. Deformation-resembling microstructure created by fluid-mediated dissolution–precipitation reactions

    Science.gov (United States)

    Spruzeniece, Liene; Piazolo, Sandra; Maynard-Casely, Helen E.

    2017-01-01

    Deformation microstructures are widely used for reconstructing tectono-metamorphic events recorded in rocks. In crustal settings deformation is often accompanied and/or succeeded by fluid infiltration and dissolution–precipitation reactions. However, the microstructural consequences of dissolution–precipitation in minerals have not been investigated experimentally. Here we conducted experiments where KBr crystals were reacted with a saturated KCl-H2O fluid. The results show that reaction products, formed in the absence of deformation, inherit the general crystallographic orientation from their parents, but also display a development of new microstructures that are typical in deformed minerals, such as apparent bending of crystal lattices and new subgrain domains, separated by low-angle and, in some cases, high-angle boundaries. Our work suggests that fluid-mediated dissolution–precipitation reactions can lead to a development of potentially misleading microstructures. We propose a set of criteria that may help in distinguishing such microstructures from the ones that are created by crystal-plastic deformation. PMID:28128202

  10. Carbon dioxide released from subduction zones by fluid-mediated reactions

    Science.gov (United States)

    Ague, Jay J.; Nicolescu, Stefan

    2014-05-01

    The balance between the subduction of carbonate mineral-bearing rocks into Earth's mantle and the return of CO2 to the atmosphere by volcanic and metamorphic degassing is critical to the carbon cycle. Carbon is thought to be released from subducted rocks mostly by simple devolatilization reactions. However, these reactions will also retain large amounts of carbon within the subducting slab and have difficulty in accounting for the mass of CO2 emitted from volcanic arcs. Carbon release may therefore occur via fluid-induced dissolution of calcium carbonate. Here we use carbonate δ18O and δ13C systematics, combined with analyses of rock and fluid inclusion mineralogy and geochemistry, to investigate the alteration of the exhumed Eocene Cycladic subduction complex on the Syros and Tinos islands, Greece. We find that in marble rocks adjacent to two fluid conduits that were active during subduction, the abundance of calcium carbonate drastically decreases approaching the conduits, whereas silicate minerals increase. Up to 60-90% of the CO2 was released from the rocks--far greater than expected via simple devolatilization reactions. The δ18O of the carbonate minerals is 5-10 lighter than is typical for metamorphosed carbonate rocks, implying that isotopically light oxygen was transported by fluid infiltration from the surroundings. We suggest that fluid-mediated carbonate mineral removal, accompanied by silicate mineral precipitation, provides a mechanism for the release of enormous amounts of CO2 from subduction zones.

  11. Target-specific variants of Flp recombinase mediate genome engineering reactions in mammalian cells.

    Science.gov (United States)

    Shah, Riddhi; Li, Feng; Voziyanova, Eugenia; Voziyanov, Yuri

    2015-09-01

    Genome engineering relies on DNA-modifying enzymes that are able to locate a DNA sequence of interest and initiate a desired genome rearrangement. Currently, the field predominantly utilizes site-specific DNA nucleases that depend on the host DNA repair machinery to complete a genome modification task. We show here that genome engineering approaches that employ target-specific variants of the self-sufficient, versatile site-specific DNA recombinase Flp can be developed into promising alternatives. We demonstrate that the Flp variant evolved to recombine an FRT-like sequence, FL-IL10A, which is located upstream of the human interleukin-10 gene, and can target this sequence in the model setting of Chinese hamster ovary and human embryonic kidney 293 cells. This target-specific Flp variant is able to perform the integration reaction and, when paired with another recombinase, the dual recombinase-mediated cassette exchange reaction. The efficiency of the integration reaction in human cells can be enhanced by 'humanizing' the Flp variant gene and by adding the nuclear localization sequence to the recombinase.

  12. Acrosome-specific gene AEP1: identification, characterization and roles in spermatogenesis.

    Science.gov (United States)

    Luk, John M; Lee, Nikki P Y; Shum, Cathy K; Lam, Brian Y; Siu, Annie F M; Che, Chi-Ming; Tam, Po-Chor; Cheung, Annie N Y; Yang, Z M; Lin, Yi-Nan; Matzuk, Martin M; Lee, Kai-Fai; Yeung, William S B

    2006-12-01

    Spermatogenesis is a tightly regulated process leading to the development of spermatozoa. To elucidate the molecular spermatogenic mechanisms, we identified an acrosome-specific gene AEP1 in spermatids, which is located in rat chromosome 17p14 with a transcript size of 3,091 bp encoding a signal peptide, zinc finger-like motif, coiled-coil region, several predicted glycosylation and phosphorylation sites. Northern blot and RT-PCR analyses revealed the restricted expression of AEP1 to the testis only. In postnatal rat testes, AEP1 mRNA became detectable from postnatal 25 dpp (round spermatids) and onwards. By using in situ hybridization (ISH) and flow cytometry-fluorescent ISH, only the haploid spermatids yielded the positive AEP1 signal. Immunohistochemistry showed that AEP1 was expressed in the acrosomal cap of late-staged germ cells in rat testis, and co-localized with the acrosomal marker, peanut agglutinin. The spatial expression of AEP1 immunoreactivity in testis was conserved among diverse mammalian species (rat, pig, monkey, human). To further study its roles in spermatogenesis, we showed AEP1 and beta-actin was associated together in complex by co-immunoprecipitation in adult germ cells and by immunofluorescence assay in isolated spermatozoon. In human testes diagnosed with hypospermatogenesis, lower expression of AEP1 was observed, whereas there was no detectable signal in undescended testes. In short, AEP1 is an evolutionary-conserved acrosome-specific gene and likely functions in acrosome-cap formation.

  13. Remodeling of the plasma membrane in preparation for sperm-egg recognition: roles of acrosomal proteins.

    Science.gov (United States)

    Tanphaichitr, Nongnuj; Kongmanas, Kessiri; Kruevaisayawan, Hathairat; Saewu, Arpornrad; Sugeng, Clarissa; Fernandes, Jason; Souda, Puneet; Angel, Jonathan B; Faull, Kym F; Aitken, R John; Whitelegge, Julian; Hardy, Daniel; Berger, Trish; Baker, Mark

    2015-01-01

    The interaction of sperm with the egg's extracellular matrix, the zona pellucida (ZP) is the first step of the union between male and female gametes. The molecular mechanisms of this process have been studied for the past six decades with the results obtained being both interesting and confusing. In this article, we describe our recent work, which attempts to address two lines of questions from previous studies. First, because there are numerous ZP binding proteins reported by various researchers, how do these proteins act together in sperm-ZP interaction? Second, why do a number of acrosomal proteins have ZP affinity? Are they involved mainly in the initial sperm-ZP binding or rather in anchoring acrosome reacting/reacted spermatozoa to the ZP? Our studies reveal that a number of ZP binding proteins and chaperones, extracted from the anterior sperm head plasma membrane, coexist as high molecular weight (HMW) complexes, and that these complexes in capacitated spermatozoa have preferential ability to bind to the ZP. Zonadhesin (ZAN), known as an acrosomal protein with ZP affinity, is one of these proteins in the HMW complexes. Immunoprecipitation indicates that ZAN interacts with other acrosomal proteins, proacrosin/acrosin and sp32 (ACRBP), also present in the HMW complexes. Immunodetection of ZAN and proacrosin/acrosin on spermatozoa further indicates that both proteins traffic to the sperm head surface during capacitation where the sperm acrosomal matrix is still intact, and therefore they are likely involved in the initial sperm-ZP binding step.

  14. immunologically mediated transfusional reactions Reacciones transfusionales mediadas inmunológicamente

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    Elkín Ferdinand Cardona Duque

    2001-01-01

    Full Text Available The potential complications of blood transfusion therapy are multiple but most of them occur only in patients requiring repeated transfusions. Risks associated with transfusion of a single unit of blood are low; however, they must be weighted against the benefits at the time each transfusion is ordered. Transfusion reactions can be classified as either immunologic or non-immunologic. Many immune reactions are caused by stimulation of antibody production by foreign alloantigens present on transfused red cells, leukocytes, platelets, or plasma proteins. Such alloimmunization may lead to future immunologically mediated reactions when transfusions carrying these antigens are administered. These include hemolytic reactions caused by red blood cell incompatibility; febrile or pulmonary reactions caused by leukocytes and platelet antigens; allergic or anaphylactic reactions caused by antibodies reacting with soluble antigens, usually plasma proteins, and other reactions of lesser importance. Son muchas las complicaciones potenciales de la terapia transfusional, pero la mayoría se presentan en pacientes que requieren múltiples transfusiones. Los riesgos asociados con la transfusión de una unidad sanguínea son realmente bajos pero deben considerarse contra los beneficios que se buscan al ordenarla. Las reacciones transfusionales se pueden clasificar como inmunológicas y no inmunológicas. Muchas de las primeras son causadas por estimulación de los anticuerpos por parte de los antígenos presentes en la transfusión de glóbulos rojos, leucocitos, plaquetas o proteínas del plasma. Esa isoinmunización puede llevar a una reacción futura cuando dichos antígenos sean transfundidos nuevamente al paciente. Entre las posibilidades se incluyen la hemólisis por incompatibilidad; las reacciones febriles o pulmonares causadas por antígenos en las plaquetas o los leucocitos; los fenómenos alérgicos o anafilácticos debidos a anticuerpos que reaccionan

  15. NMR measurement of hydrodynamic dispersion in porous media subject to biofilm mediated precipitation reactions.

    Science.gov (United States)

    Fridjonsson, Einar O; Seymour, Joseph D; Schultz, Logan N; Gerlach, Robin; Cunningham, Alfred B; Codd, Sarah L

    2011-03-01

    Noninvasive measurements of hydrodynamic dispersion by nuclear magnetic resonance (NMR) are made in a model porous system before and after a biologically mediated precipitation reaction. Traditional magnetic resonance imaging (MRI) was unable to detect the small scale changes in pore structure visualized during light microscopy analysis after destructive sampling of the porous medium. However, pulse gradient spin echo nuclear magnetic resonance (PGSE NMR) measurements clearly indicated a change in hydrodynamics including increased pore scale mixing. These changes were detected through time-dependent measurement of the propagator by PGSE NMR. The dynamics indicate an increased pore scale mixing which alters the preasymptotic approach to asymptotic Gaussian dynamics governed by the advection diffusion equation. The methods described here can be used in the future to directly measure the transport of solutes in biomineral-affected porous media and contribute towards reactive transport models, which take into account the influence of pore scale changes in hydrodynamics.

  16. Water mediated hydrogen abstraction mechanism in the radical reaction between HOSO and NO2

    Science.gov (United States)

    Lesar, Antonija; Tušar, Simona

    2016-05-01

    The effect of water molecules on the direct hydrogen abstraction from HOSO by NO2 was investigated for the first time. Stationary points were located at the B3LYP/6-311+G(2df,2pd) and CCSD/aug-cc-pVDZ levels of theory whereas energetics was further improved by CBS-QB3 and G4 composite methods. The fractions of hydrated radical complexes were estimated in order to assess atmospheric relevance of the title reaction. The energy barrier of the water mediated process becomes negligible. The formations of post-reactive complexes from pre-reactive complexes are energetically very favorable and the processes are spontaneous suggesting that they should be very feasible under atmospheric conditions.

  17. SnCl2/Cu-Mediated Carbonyl Allylation Reaction in Water:Scope,Selectivity and Mechanism

    Institute of Scientific and Technical Information of China (English)

    TAN,Xiang-Hui(谭翔晖); HOU,Yong-Quan(侯永泉); LIU,Lei(刘磊); GUO,Qing-Xiang(郭庆祥)

    2004-01-01

    Copper was found to be able to promote the SnC12-mediated carbonyl allylation reactions in water,giving the corresponding homoallylic alcohol products in very high yields.Detailed studies showed that the reaction could be applied to a variety of carbonyl compounds including those with hydroxyl,amino and nitro groups.It was also found that this reaction showed good regioselectivities for some substrates.Furthermore,carefully controled experiments and in situ NMR measurements provided important insights into the mechanism of the newly developed reaction.

  18. Silymarin protects plasma membrane and acrosome integrity in sperm treated with sodium arsenite

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    Farzaneh Eskandari

    2016-01-01

    Full Text Available Background: Exposure to arsenic is associated with impairment of male reproductive function by inducing oxidative stress. Silymarin with an antioxidant property scavenges free radicals. Objective: The aim of this study was to investigate if silymarin can prevent the adverse effects of sodium arsenite on ram sperm plasma membrane and acrosome integrity. Materials and Methods: Ram epidydimal spermatozoa were divided into five groups: spermatozoa at 0 hr, spermatozoa at 180 min (control, spermatozoa treated with silymarin (20 μM + sodium arsenite (10 μM for 180 min, spermatozoa treated with sodium arsenite (10 μM for 180 min and spermatozoa treated with silymarin (20 μM for 180 min. Double staining of Hoechst and propidium iodide was performed to evaluate sperm plasma membrane integrity, whereas comassie brilliant blue staining was used to assess acrosome integrity. Results: Plasma membrane (p< 0.001 and acrosome integrity (p< 0.05 of the spermatozoa were significantly reduced in sodium arsenite group compared to the control. In silymarin + sodium arsenite group, silymarin was able to significantly (p< 0.001 ameliorate the adverse effects of sodium arsenite on these sperm parameters compared to sodium arsenite group. The incubation of sperm for 180 min (control group showed a significant (p< 0.001 decrease in acrosome integrity compared to the spermatozoa at 0 hour. The application of silymarin alone for 180 min could also significantly (p< 0.05 increase sperm acrosome integrity compared to the control. Conclusion: Silymarin as a potent antioxidant could compensate the adverse effects of sodium arsenite on the ram sperm plasma membrane and acrosome integrity.

  19. Involvement of complexin 2 in docking, locking and unlocking of different SNARE complexes during sperm capacitation and induced acrosomal exocytosis.

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    Pei-Shiue J Tsai

    Full Text Available Acrosomal exocytosis (AE is an intracellular multipoint fusion reaction of the sperm plasma membrane (PM with the outer acrosomal membrane (OAM. This unique exocytotic event enables the penetration of the sperm through the zona pellucida of the oocyte. We previously observed a stable docking of OAM to the PM brought about by the formation of the trans-SNARE complex (syntaxin 1B, SNAP 23 and VAMP 3. By using electron microscopy, immunochemistry and immunofluorescence techniques in combination with functional studies and proteomic approaches, we here demonstrate that calcium ionophore-induced AE results in the formation of unilamellar hybrid membrane vesicles containing a mixture of components originating from the two fused membranes. These mixed vesicles (MV do not contain the earlier reported trimeric SNARE complex but instead possess a novel trimeric SNARE complex that contained syntaxin 3, SNAP 23 and VAMP 2, with an additional SNARE interacting protein, complexin 2. Our data indicate that the earlier reported raft and capacitation-dependent docking phenomenon between the PM and OAM allows a specific rearrangement of molecules between the two docked membranes and is involved in (1 recruiting SNAREs and complexin 2 in the newly formed lipid-ordered microdomains, (2 the assembly of a fusion-driving SNARE complex which executes Ca(2+-dependent AE, (3 the disassembly of the earlier reported docking SNARE complex, (4 the recruitment of secondary zona binding proteins at the zona interacting sperm surface. The possibility to study separate and dynamic interactions between SNARE proteins, complexin and Ca(2+ which are all involved in AE make sperm an ideal model for studying exocytosis.

  20. Giant, accordioned sperm acrosomes of the greater bulldog bat, Noctilio leporinus.

    Science.gov (United States)

    Phillips, D M; Rasweiler, J J; Muradali, F

    1997-09-01

    Sperm of the greater bulldog bat Noctilio leporinus display an architecture that is totally unique among mammalian spermatozoa. The sperm head of Noctilio is extraordinarily large and flat and lies eccentrically with respect to the sperm tail. The major portion of the atypically large acrosome lies anterior to the nucleus and is shaped into a dozen accordionlike folds that run parallel to the long axis of the sperm. The ridge of each fold is shaped into approximately 60 minute, evenly spaced rises that extend along the entire length of the fold. We speculate that acrosome ridges may serve to strengthen the sperm head during transport.

  1. Hapten-Induced Contact Hypersensitivity, Autoimmune Reactions, and Tumor Regression: Plausibility of Mediating Antitumor Immunity

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    Dan A. Erkes

    2014-01-01

    Full Text Available Haptens are small molecule irritants that bind to proteins and elicit an immune response. Haptens have been commonly used to study allergic contact dermatitis (ACD using animal contact hypersensitivity (CHS models. However, extensive research into contact hypersensitivity has offered a confusing and intriguing mechanism of allergic reactions occurring in the skin. The abilities of haptens to induce such reactions have been frequently utilized to study the mechanisms of inflammatory bowel disease (IBD to induce autoimmune-like responses such as autoimmune hemolytic anemia and to elicit viral wart and tumor regression. Hapten-induced tumor regression has been studied since the mid-1900s and relies on four major concepts: (1 ex vivo haptenation, (2 in situ haptenation, (3 epifocal hapten application, and (4 antigen-hapten conjugate injection. Each of these approaches elicits unique responses in mice and humans. The present review attempts to provide a critical appraisal of the hapten-mediated tumor treatments and offers insights for future development of the field.

  2. Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

    Directory of Open Access Journals (Sweden)

    Burkhard Koenig

    2011-01-01

    Full Text Available N-Arylated aliphatic and aromatic amines are important substituents in many biologically active compounds. In the last few years, transition-metal-mediated N-aryl bond formation has become a standard procedure for the introduction of amines into aromatic systems. While N-arylation of simple aromatic halides by simple amines works with many of the described methods in high yield, the reactions may require detailed optimization if applied to the synthesis of complex molecules with additional functional groups, such as natural products or drugs. We discuss and compare in this review the three main N-arylation methods in their application to the synthesis of biologically active compounds: Palladium-catalysed Buchwald–Hartwig-type reactions, copper-mediated Ullmann-type and Chan–Lam-type N-arylation reactions. The discussed examples show that palladium-catalysed reactions are favoured for large-scale applications and tolerate sterically demanding substituents on the coupling partners better than Chan–Lam reactions. Chan–Lam N-arylations are particularly mild and do not require additional ligands, which facilitates the work-up. However, reaction times can be very long. Ullmann- and Buchwald–Hartwig-type methods have been used in intramolecular reactions, giving access to complex ring structures. All three N-arylation methods have specific advantages and disadvantages that should be considered when selecting the reaction conditions for a desired C–N bond formation in the course of a total synthesis or drug synthesis.

  3. A NEW METHOD TO DETECT ACROSOME-REACTED SPERMATOZOA USING BIOTINYLATED SOYBEAN TRYPSIN-INHIBITOR

    NARCIS (Netherlands)

    ARTS, EGJM; KUIKEN, J; JAGER, S

    1994-01-01

    Objective: To develop a method to detect acrosome-reacted spermatozoa on human zonae pellucidae using only commercially available reagents and without need for sperm fixation. Design: Sperm head labeling with biotinylated soybean trypsin inhibitor (SBTI-biotin) was compared with results of a known m

  4. Kinetics of microbially mediated reactions: dissimilatory sulfate reduction in saltmarsh sediments (Sapelo Island, Georgia, USA)

    Science.gov (United States)

    Roychoudhury, Alakendra N.; Van Cappellen, Philippe; Kostka, Joel E.; Viollier, Eric

    2003-04-01

    A sediment disk reactor was tested in once flow-through mode to retrieve kinetic parameters for the Monod rate law that describes sulfate reduction. The experimental method was compared with a previously described procedure by the authors where a sediment plug-flow reactor was operated in a recirculation mode. In recirculation mode, accumulation of metabolic byproducts in certain cases may result in negative feedback, thus preventing accurate determination of kinetic information. The method described in this article provides an alternative to the recirculation sediment plug-flow-through reactor technique for retrieving kinetic parameters of microbially mediated reactions in aquatic sediments. For sulfate reduction in a saltmarsh site, a maximum estimate of the half-saturation concentration, Ks, of 204±26 μM and a maximum reaction rate, Rm, of 2846±129 nmol cm( wet sediment ) 3 d-1 was determined. The Ks value obtained was consistent with the one estimated previously (K s=240±20 μM) from a different site within the same saltmarsh mud flat using a recirculating reactor. From the Rm value and reduction rates determined using 35SO 42- incubation experiments, we infer that sulfate reduction is limited in the field. Substrate availability is not the main contributor for the limitation, however. Competition from other microbes, such as iron reducers affects the activity of sulfate reducers in the suboxic to anoxic zones, whereas aerobes compete in the oxic zone. High sulfide concentration in the pore water may also have acted as a toxin to the sulfate reducers in the field.

  5. The pivotal role of fibrocytes and mast cells in mediating fibrotic reactions to biomaterials.

    Science.gov (United States)

    Thevenot, Paul T; Baker, David W; Weng, Hong; Sun, Man-Wu; Tang, Liping

    2011-11-01

    Almost all biomaterial implants are surrounded by a fibrotic capsule, although the mechanism of biomaterial-mediated fibrotic reactions is mostly unclear. To search for the types of cells responsible for triggering the tissue responses, we used poly-L glycolic acid polymers capable of releasing various reagents. We first identified that CD45(+)/Collagen 1(+) fibrocytes are recruited and resided within the fibrotic capsule at the implant interface. Interestingly, we found that the recruitment of fibrocytes and the extent of fibrotic tissue formation (collagen type I production) were substantially enhanced and reduced by the localized release of compound 48/80 and cromolyn, respectively. Since it is well established that compound 48/80 and cromolyn alter mast cell reactions, we hypothesized that mast cells are responsible for triggering fibrocyte recruitment and subsequent fibrotic capsule formation surrounding biomaterial implants. To directly test this hypothesis, similar studies were carried out using mast cell deficient mice, WBB6F1/J-Kit(W)/Kit(W-v)/, and their congenic controls. Indeed, mast cell deficient mice prompted substantially less fibrocyte and myofibroblast responses in comparison to C57 wild type mice controls. Most interestingly, subcutaneous mast cell reconstitution of WBB6F1/J-Kit(W)/Kit(W-v)/J mice almost completely restored the fibrocyte response in comparison to the C57 wild type response. These results indicate that the initial biomaterial interaction resulting in the stimulation of mast cells and degranulation byproducts not only stimulates the inflammatory cascade but significantly alters the downstream fibrocyte response and degree of fibrosis.

  6. Ion-Mediated Polymerase Chain Reactions Performed with an Electronically Driven Microfluidic Device.

    Science.gov (United States)

    Zhang, Yi; Li, Qian; Guo, Linjie; Huang, Qing; Shi, Jiye; Yang, Yang; Liu, Dongsheng; Fan, Chunhai

    2016-09-26

    The polymerase chain reaction (PCR) is a powerful method for exponentially amplifying very low amounts of target DNA from genetic, clinical, and forensic samples. However, the heating and cooling steps in PCR largely hamper the miniaturization of thermocyclers for on-site detection of pathogens and point-of-care tests. Herein, we devise an ion-mediated PCR (IM-PCR) strategy by exploiting ion-induced DNA denaturation/renaturation cycles. DNA duplexes are effectively denatured in alkaline solutions; whereas, the denatured single-stranded DNA strands readily reform duplexes at neutral pH. By using an integrated microchip that can programmably control the solution pH simply switching the potential in a range of several hundred millivolts, we can trigger IM-PCR at a constant temperature. Analogously to thermal cycling, 30 cycles of pH-induced denaturation/renaturation were used to amplify protein DNA fragments as confirmed by DNA sequencing. We anticipate that this portable, low-cost, and scalable IM-PCR holds great promise for widespread biological, clinical, and environmental applications.

  7. IgE- and IgG mediated severe anaphylactic platelet transfusion reaction in a known case of cerebral malaria

    Directory of Open Access Journals (Sweden)

    B Shanthi

    2013-01-01

    Full Text Available Background: Allergic reactions occur commonly in transfusion practice. However, severe anaphylactic reactions are rare; anti-IgA (IgA: Immunoglobulin A in IgA-deficient patients is one of the well-illustrated and reported causes for such reactions. However, IgE-mediated hypersensitivity reaction through blood component transfusion may be caused in parasitic hyperimmunization for IgG and IgE antibodies. Case Report: We have evaluated here a severe anaphylactic transfusion reaction retrospectively in an 18year-old male, a known case of cerebral malaria, developed after platelet transfusions. The examination and investigations revealed classical signs and symptoms of anaphylaxis along with a significant rise in the serum IgE antibody level and IgG by hemagglutination method. Initial mild allergic reaction was followed by severe anaphylactic reaction after the second transfusion of platelets. Conclusion: Based on these results, screening of patients and donors with mild allergic reactions to IgE antibodies may help in understanding the pathogenesis as well as in planning for preventive desensitization and measures for safe transfusion.

  8. Spermatogenesis of the green-lipped mussel Perna viridis with dual patterns of acrosome and tail development in spermatids

    Science.gov (United States)

    Reunov, A. A.; Au, D. W. T.; Wu, R. S. S.

    1999-08-01

    Spermatogenesis in the mussel Perna viridis was studied by electron microscopy. Results demonstrated that cytological development in spermatogonia and spermatocytes was similar to that previously described in other Mytilidae. Acrosome formation began with the arising of proacrosomal vesicles in spermatogonia. The abundance of proacrosomal vesicles increased in spermatocytes, which were flagellated. However, during spermiogenesis, dual patterns of acrosome development as well as flagellum development could be found among spermatids in a male gonad. The two lines of acrosome formation in spermatids ultimately gave rise to morphologically similar acrosomes. The two lines of flagellum development in spermatids resulted in the formation of sperm cells with either a typically posteriorly directed tail or an anteriorly directed tail.

  9. Validation of the polysemen admixture on viability and acrosomal morphology of boar spermatozoa

    Directory of Open Access Journals (Sweden)

    Ogbuewu IP

    2007-07-01

    Full Text Available Semen were collected using artificial vagina (AV, from 5 large white boars aged 2-2.5 years twice a week for 16 weeks in each of the two seasons, early rainy (ER and late rainy (LR seasons, to determine the effects of multiple semen pool admixture on the viability and acrosomal morphology. The semen qualities studied were sperm motility, live sperm and sperm concentration, while the acrosomal parameters includes normal apical ridge (NAR, damaged apical ridge (DAR, missing apical ridge (MAR and loose apical ridge (LAC. There were no significant (P>0.05 seasonal effects. Three-boar semen admixture gave the highest percentage NAR, motility, live sperm concentration and least DAR and LAC, although these were not significantly (P>0.05 different from the 2-boar semen admixture. The result of this study suggests that 3-boar semen admixture is most suitable for use in artificial insemination program.

  10. Sm/TiCl4 (cat.) system-mediated intermolecular and intramolecular reductive coupling reactions of ketones with esters

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-kui; XU Dan-qian; XU Zhen-yuan; ZHANG Yong-min

    2007-01-01

    Sm/TiCl4 system could well integrate the high reactivity of samarium(Ⅱ) and high deoxygenation capacity of low valent titanium within one system. In this paper, the intermolecular and intramolecular reductive coupling reactions of ketones with esters mediated by metallic samarium (Sm) and a catalytic amount of titanium tetrachloride (TiCl4) were successfully developed. A series of substituted ketones and cyclic β-keto-esters were prepared in moderate to good yields under reflux and neutral conditions.

  11. A route to hydroxylfluorenes: TsOH-mediated condensation reactions of 1,3-diketones with propargylic alcohols

    KAUST Repository

    Yao, Liangfeng

    2012-01-01

    An efficient method of preparing hydroxylfluorenes by TsOH-mediated tandem alkylation/rearrangements of propargylic alcohols with 1,3-diketones is described. These reactions are accomplished in moderate to good yields under mild conditions to offer a straightforward and convenient one step synthetic route to hydroxylfluorene derivatives through a plausible mechanism involving a sequence of dehydration, addition, rearrangement and aromatization. This journal is © The Royal Society of Chemistry 2012.

  12. Effects of acrosomal conditions of frozen-thawed spermatozoa on the results of artificial insemination in Japanese Black cattle.

    Science.gov (United States)

    Kishida, Kazumi; Sakase, Mitsuhiro; Minami, Kenta; Arai, Miyuki M; Syoji, Reiko; Kohama, Namiko; Akiyama, Takayuki; Oka, Akio; Harayama, Hiroshi; Fukushima, Moriyuki

    2015-01-01

    The purposes of this study were to examine the relationship between male artificial insemination (AI) fertility and sperm acrosomal conditions assessed by new and conventional staining techniques and to identify possible reproductive dysfunctions causing low conception rates in AI using frozen-thawed spermatozoa with poor acrosomal conditions in Japanese Black bulls. We investigated individual differences among bulls in the results concerning (1) acrosomal conditions of frozen-thawed spermatozoa as assessed by not merely peanut agglutinin-lectin staining (a conventional staining technique) but also immunostaining of acrosomal tyrosine-phosphorylated proteins (a new staining technique), (2) routine AI using frozen-thawed spermatozoa as assessed by pregnancy diagnosis, (3) in vivo fertilization of frozen-thawed spermatozoa and early development of fertilized eggs as assessed by superovulation/AI-embryo collection tests and (4) in vitro fertilization of frozen-thawed spermatozoa with oocytes. The percentages of frozen-thawed spermatozoa with normal acrosomal conditions assessed by the abovementioned staining techniques were significantly correlated with the conception rates of routine AI, rates of transferable embryos in superovulation/AI-embryo collection tests and in vitro fertilization rates. These results are consistent with new suggestions that the distribution of acrosomal tyrosine-phosphorylated proteins as well as the acrosomal morphology of frozen-thawed spermatozoa are AI fertility-associated markers that are valid for the prediction of AI results and that low conception rates in AI using frozen-thawed spermatozoa with poor acrosomal conditions result from reproductive dysfunctions in the processes between sperm insemination into females and early embryo development, probably failed fertilization of frozen-thawed spermatozoa with oocytes.

  13. FUSION OF ARTIFICIAL MEMBRANES WITH MAMMALIAN SPERMATOZOA - SPECIFIC INVOLVEMENT OF THE EQUATORIAL SEGMENT AFTER ACROSOME REACTION

    NARCIS (Netherlands)

    ARTS, EGJM; KUIKEN, J; JAGER, S; HOEKSTRA, D

    1993-01-01

    The fusogenic properties of bovine and human spermatozoa membranes were investigated, using phospholipid bilayers (liposomes) as target membranes. Fusion was monitored by following lipid mixing, as revealed by an assay based on resonance-energy transfer. In addition, fusion was visualized by fluores

  14. Effect of cholesterol-loaded-cyclodextrin on sperm viability and acrosome reaction in boar semen cryopreservation.

    Science.gov (United States)

    Lee, Yong-Seung; Lee, Seunghyung; Lee, Sang-Hee; Yang, Boo-Keun; Park, Choon-Keun

    2015-08-01

    This study was undertaken to examine the effect of cholesterol-loaded-cyclodextrin (CLC) on boar sperm viability and spermatozoa cryosurvival during boar semen cryopreservation, and methyl-β-cyclodextrin (MBCD) was treated for comparing with CLC. Boar semen treated with CLC and MBCD before freezing process to monitor the effect on survival and capacitation status by flow cytometry with appropriate fluorescent probes. Sperm viability was higher in 1.5mg CLC-treated sperm (76.9±1.01%, Psperm before cryopreservation (58.7±1.31% and 60.3±0.31%, respectively). For CTC patterns, F-pattern was higher in CLC treated sperm than MBCD-treated sperm, for B-pattern was higher in CLC-treated sperm than fresh sperm (Psperm) was lower in CLC-treated sperm than MBCD-treated sperm (Pboar semen.

  15. Acrosome membrane integrity and cryocapacitation are related to cholesterol content of bull spermatozoa

    Institute of Scientific and Technical Information of China (English)

    Srivastava N; Srivastava SK; Ghosh SK; Amit Kumar; Perumal P; Jerome A

    2013-01-01

    Objective: To evaluate the cryoinjury prediction of spermatozoa in relation to its cholesterol content at fresh and frozen-thaw stages. Methods: Ejaculates (n=12) were processed for cryopreservation, acrosome integrity (fluorescent and giemsa stains), cryoinjury (distribution of non capacitated, capacitated and acrosome reacted, pattern F, B and AR, respectively of Chlortetracycline, CTC assay), in vitro fertiltiy (IVF) and cholesterol content of spermatozoa at fresh, pre-freeze and frozen-thaw stages were evaluated. Values were fitted in prediction equation to predict acrosome integrity (AI) and cryoinjury. Results: Study indicated that cholesterol content of fresh spermatozoa can be used to predict cholesterol content of spermatozoa at pre-freeze and frozen-thaw stages of cryopreservation protocol with medium to high level of accuracy (P<0.05 and P<0.01, respectively). Cholesterol content of fresh spermatozoa can be used to predict AI, pattern B and AR and Penetration Index (PI) of IVF with medium level of accuracy (P<0.05) at frozen-thaw but not at pre-freeze stage. Similarly cholesterol content of frozen-thaw spermatozoa can be used to predict AI and pattern AR of frozen-thaw spermatozoa with medium level of accuracy (P<0.05). Conclusion: This study revealed strong evidence that cholesterol content of fresh as well as frozen-thaw bull spermatozoa can be a good predictor of level of cryoinjury following preservation at ultra low temperature.

  16. Effects of Sperm Acrosomal Integrity and Protamine Deficiency on In Vitro Fertilization and Pregnancy Rate

    Directory of Open Access Journals (Sweden)

    Marziyeh Tavalaee

    2007-01-01

    Full Text Available Background: The objective of this study was to evaluate the relationship between protaminedeficiency, and acrosomal integrity with fertilization and pregnancy rate in patients undergone in vitrofertilization (IVF.Material &Methods: Semen samples from 70 infertile couples undergoing IVF at Isfahan Fertility andInfertility center were assessed in this study. Semen analysis was carried out according to WHO criteria.Protamine deficiency, Sperm morphology and acrosin activity were assessed by Chromomycin A3(CMA3, Papanicolaou staining and Gelatinolysis tests, respectively. Coefficients of correlation andstudent t-test were carried out using the Statistical Package for the Social Studies (SPSS 11.5 and Pvaluelower than 0.05 was considered as significant.Results: Fertilization rate, percentage of halo formation, mean halo diameter and abnormalmorphology show a significant correlation with percentage of CMA3 positivity. CMA3 positivity,percentage of halo, mean halo and sperm morphology showed a significant correlation with fertilizationrate. Among the aforementioned parameters percentage of halo had the highest correlation. In thepresent study patients were divided into two groups according to pregnancy status. None of the studiedparameters were significantly different between pregnant and non-pregnant patients. However,percentage of halo formation showed a slightly significant difference (r=0.306; P=0.058.Conclusion: The results of this study revealed that, even though sperm morphology, sperm protaminecontent and acrosome formation are events related to spermiogenesis, sperm acrosomal integrityassessed by percentage of halo formation has more profound effect on fertilization rate and pregnancyoutcome during IVF procedure.

  17. Social Reactions to Sexual Assault Disclosure and Problem Drinking: Mediating Effects of Perceived Control and PTSD

    OpenAIRE

    Peter-Hagene, Liana C.; Ullman, Sarah E.

    2013-01-01

    Sexual assault survivors receive various positive and negative social reactions to assault disclosures, yet little is known about mechanisms linking these social reactions to posttraumatic stress disorder (PTSD) symptoms and problem drinking. Data from a large, diverse sample of women who had experienced adult sexual assault was analyzed with structural equation modeling to test a theoretical model of the relationships between specific negative social reactions (e.g., controlling, infantilizi...

  18. Adaptive and innate immune reactions regulating mast cell activation: from receptor-mediated signaling to responses

    DEFF Research Database (Denmark)

    Tkaczyk, Christine; Jensen, Bettina M; Iwaki, Shoko

    2006-01-01

    differentially activate multiple signaling pathways within the mast cells required for the generation and/or release of inflammatory mediators. Thus, the composition of the suite of mediators released and the physiologic ramifications of these responses are dependent on the stimuli and the microenvironment...... activation. The exact interconnections between the signaling pathways initiated by the surface receptors described in this article remain to be completely worked out; thus, this remains a topic for future investigation....

  19. Pyrovanadolysis: a Pyrophosphorolysis-like Reaction Mediated by Pyrovanadate MN2plus and DNA Polymerase of Bacteriophage T7

    Energy Technology Data Exchange (ETDEWEB)

    B Akabayov; A Kulczyk; S Akabayov; C Thiele; L McLaughlin; B Beauchamp; C Richardson

    2011-12-31

    DNA polymerases catalyze the 3'-5'-pyrophosphorolysis of a DNA primer annealed to a DNA template in the presence of pyrophosphate (PP{sub i}). In this reversal of the polymerization reaction, deoxynucleotides in DNA are converted to deoxynucleoside 5'-triphosphates. Based on the charge, size, and geometry of the oxygen connecting the two phosphorus atoms of PP{sub i}, a variety of compounds was examined for their ability to carry out a reaction similar to pyrophosphorolysis. We describe a manganese-mediated pyrophosphorolysis-like activity using pyrovanadate (VV) catalyzed by the DNA polymerase of bacteriophage T7. We designate this reaction pyrovanadolysis. X-ray absorption spectroscopy reveals a shorter Mn-V distance of the polymerase-VV complex than the Mn-P distance of the polymerase-PP{sub i} complex. This structural arrangement at the active site accounts for the enzymatic activation by Mn-VV. We propose that the Mn{sup 2+}, larger than Mg{sup 2+}, fits the polymerase active site to mediate binding of VV into the active site of the polymerase. Our results may be the first documentation that vanadium can substitute for phosphorus in biological processes.

  20. immunologically mediated transfusional reactions Reacciones transfusionales mediadas inmunológicamente

    OpenAIRE

    Elkín Ferdinand Cardona Duque

    2001-01-01

    The potential complications of blood transfusion therapy are multiple but most of them occur only in patients requiring repeated transfusions. Risks associated with transfusion of a single unit of blood are low; however, they must be weighted against the benefits at the time each transfusion is ordered. Transfusion reactions can be classified as either immunologic or non-immunologic. Many immune reactions are caused by stimulation of antibody production by foreign alloantigens present on tran...

  1. Tri-n-butylphosphine Mediated Ring-Opening Reactions of Aziridines or Epoxides with Diphenyl Diselenide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wan-Xuan; YE Kang; RUAN Shan; CHEN Zu-Xing; XIA Qing-Hua

    2007-01-01

    Aziridines and epoxides were reacted with diphenyl diselenide in the presence of a stoichiometric amount of (n-Bu)3P, respectively, giving β-amino-or β-hydroxy selenides in moderate to excellent yields under mild conditions. In the reactions the (n-Bu)3P might act as a reductant though it was a nucleophilic catalyst in other similar ring-opening reactions.

  2. Cu-Mediated Stille Reactions of Sterically Congested Fragments: Towards the Total Synthesis of Zoanthamine

    DEFF Research Database (Denmark)

    Nielsen, Thomas E.; Le Quement, Sebastian; Juhl, Martin;

    2005-01-01

    A study on the Stille reaction of alkenyl iodides and starmanes with structural resemblance to retrosynthetic fragments of a projected total synthesis of the marine alkaloid zoanthamine was carried out. A range of reaction conditions was examined, and a protocol developed by Corey utilizing excess...... copper(I) chloride and lithium chloride was found to be most efficient. The methodology was successfully applied to join two major fragments of the zoanthamine skeleton. (c) 2005 Elsevier Ltd. All rights reserved....

  3. Microwave-Mediated Hetero Diels-Alder reaction: Synthesis of biologically active compounds

    OpenAIRE

    D’Aurizio, Antonio

    2009-01-01

    Heterocyclic compounds represent almost two-thirds of all the known organic compounds: they are widely distributed in nature and play a key role in a huge number of biologically important molecules including some of the most significant for human beings. A powerful tool for the synthesis of such compounds is the hetero Diels-Alder reaction (HDA), that involve a [4+2] cycloaddition reaction between heterodienes and suitable dienophiles. Among heterodienes to be used in such six-membered ...

  4. Discrimination of Arcobacter butzleri isolates by polymerase chain reaction-mediated DNA fingerprinting

    DEFF Research Database (Denmark)

    Atabay, H. I.; Bang, Dang Duong; Aydin, F.;

    2002-01-01

    Aims: The objective of this study was to subtype Arcobacter butzleri isolates using RAPD-PCR. Methods and Results: Thirty-five A. butzleri isolates obtained from chicken carcasses were examined. PCR-mediated DNA fingerprinting technique with primers of the variable sequence motifs was used...

  5. Plasma contact system activation drives anaphylaxis in severe mast cell-mediated allergic reactions

    NARCIS (Netherlands)

    Sala-Cunill, Anna; Björkqvist, Jenny; Senter, Riccardo; Guilarte, Mar; Cardona, Victoria; Labrador, Moises; Nickel, Katrin F; Butler, Lynn; Luengo, Olga; Kumar, Parvin; Labberton, Linda; Long, Andy; Di Gennaro, Antonio; Kenne, Ellinor; Jämsä, Anne; Krieger, Thorsten; Schlüter, Hartmut; Fuchs, Tobias; Flohr, Stefanie; Hassiepen, Ulrich; Cumin, Frederic; McCrae, Keith; Maas, Coen; Stavrou, Evi; Renné, Thomas

    2015-01-01

    BACKGROUND: Anaphylaxis is an acute, potentially lethal, multisystem syndrome resulting from the sudden release of mast cell-derived mediators into the circulation. OBJECTIVES AND METHODS: We report here that a plasma protease cascade, the factor XII-driven contact system, critically contributes to

  6. Anxiety sensitivity and post-traumatic stress reactions: Evidence for intrusions and physiological arousal as mediating and moderating mechanisms.

    Science.gov (United States)

    Olatunji, Bunmi O; Fan, Qianqian

    2015-08-01

    A growing body of research has implicated anxiety sensitivity (AS) and its dimensions in the development of post-traumatic stress disorder (PTSD). However, the mechanism(s) that may account for the association between AS and PTSD remains unclear. Using the "trauma film paradigm," which provides a prospective experimental tool for investigating analog intrusion development, the present study examines the extent to which intrusions mediate the association between AS and the development of posttraumatic stress reactions. After completing a measure of AS and state mood, unselected participants (n = 45) viewed a 10 min film of graphic scenes of fatal traffic accidents and then completed a second assessment of state mood. Participants then kept a daily diary to record intrusions about the film for a one-week period. Post-traumatic stress reactions about the film were then assessed after the one-week period. The results showed that general AS and physical and cognitive concerns AS predicted greater post-traumatic stress reactions about the film a week later. Furthermore, the number of intrusions the day after viewing the traumatic film, but not fear and disgust in response to the trauma film, mediated the association between general AS (and AS specifically for physical and cognitive concerns) and post-traumatic stress reactions a week later. Subsequent analysis also showed that physiological arousal during initial exposure to the traumatic film moderated the association between general AS and the number of intrusions reported the day after viewing the film. The implications of these analog findings for conceptualizing the mechanism(s) that may interact to explain the role of AS in the development of PTSD and its effective treatment are discussed.

  7. Zona Pellucida Induces Activation of Phospholipase A2 During Acrosomal Exocytosis in Guinea PigSpermatozoa

    Institute of Scientific and Technical Information of China (English)

    袁玉英; 陈文颖; 石其贤; 毛丽珍; 俞淑清; 方昕; E.R.S.Roldan

    2005-01-01

    Objective To investigate whether PLA2 is involved in ZP-stimulated acrosomal exocytosis,if Ca2+ is required for activation of PLA2,and sigal transduction pathways modulating PLA2. Methods Guinea-pig spermatozoa were capacitated and labeled in low Ca2+ medium with [14C]choline chloride or [14C] arachidonic acid,and were then exposed to millimolar Ca2+ and various reagents and stimulated with ZP. Results Precapacitated spermatozoa exposed to millimolar Ca2+ and stimulated with ZP experienced increases in arachidonic acid(AA)and lysophosphatidylcholine (lysoPC) and a parallel decrease in phosphatidylcholine (PC);these chages are indicative of PLA2 activation.Simulation with ZP also led to acrosomal exocytosis in a high proportion of spermatozoa. Lipid changes and exocytosis were prevented if spermatozoa were exposed to aristolochic acid,a PLA2 inhibitor, before treatment with ZP.Stimulation with ZP in medium without added Ca2+,or in medium with millimolar Ca2+ and EGTA or La3+ resulted in no lipid changes or exocytosis. Pretreatment with pertussis toxin,a G1 protein inhibitor, before stimulation with ZP,blocked the release of AA and lysoPC and acrosomal exocytosis.Exposure of spermatozoa to the DAG kinase inhibitor R59022 before ZP stimulation led to a significant increase in the generation of lysoPC and exocytosis.Conclusion These results indicate very strongly that PLA2 plays an essential role in ZP-induced exocytosis in spermatozoa, that PLA2 activation requires Ca2+ internalization,and that it is regulated by signal transduction pathways involving G proteins and DAG.

  8. Controlling Solution-Mediated Reaction Mechanisms of Oxygen Reduction Using Potential and Solvent for Aprotic Lithium-Oxygen Batteries.

    Science.gov (United States)

    Kwabi, David G; Tułodziecki, Michał; Pour, Nir; Itkis, Daniil M; Thompson, Carl V; Shao-Horn, Yang

    2016-04-07

    Fundamental understanding of growth mechanisms of Li2O2 in Li-O2 cells is critical for implementing batteries with high gravimetric energies. Li2O2 growth can occur first by 1e(-) transfer to O2, forming Li(+)-O2(-) and then either chemical disproportionation of Li(+)-O2(-), or a second electron transfer to Li(+)-O2(-). We demonstrate that Li2O2 growth is governed primarily by disproportionation of Li(+)-O2(-) at low overpotential, and surface-mediated electron transfer at high overpotential. We obtain evidence supporting this trend using the rotating ring disk electrode (RRDE) technique, which shows that the fraction of oxygen reduction reaction charge attributable to soluble Li(+)-O2(-)-based intermediates increases as the discharge overpotential reduces. Electrochemical quartz crystal microbalance (EQCM) measurements of oxygen reduction support this picture, and show that the dependence of the reaction mechanism on the applied potential explains the difference in Li2O2 morphologies observed at different discharge overpotentials: formation of large (∼250 nm-1 μm) toroids, and conformal coatings (<50 nm) at higher overpotentials. These results highlight that RRDE and EQCM can be used as complementary tools to gain new insights into the role of soluble and solid reaction intermediates in the growth of reaction products in metal-O2 batteries.

  9. Psychosocial stress enhances IgE-mediated triphasic cutaneous reaction in mice: Antagonism by Yokukan-san (a Kampo medicine and diazepam

    Directory of Open Access Journals (Sweden)

    Eiichi Tahara

    2001-01-01

    Conclusions: The results of the present study indicate that IgE-mediated triphasic cutaneous reactions were exacerbated by social isolation stress and suggest that Yokukan-san and diazepam antagonize isolation stress-induced cutaneous reactions partly through their sedative action on social isolation stress.

  10. Boron-mediated sequential alkyne insertion and C–C coupling reactions affording extended π-conjugated molecules

    Science.gov (United States)

    Shoji, Yoshiaki; Tanaka, Naoki; Muranaka, Sho; Shigeno, Naoki; Sugiyama, Haruka; Takenouchi, Kumiko; Hajjaj, Fatin; Fukushima, Takanori

    2016-01-01

    C–C bond coupling reactions illustrate the wealth of organic transformations, which are usually mediated by organotransition metal complexes. Here, we show that a borafluorene with a B–Cl moiety can mediate sequential alkyne insertion (1,2-carboboration) and deborylation/Csp2–Csp2 coupling reactions, leading to aromatic molecules. The first step, which affords a borepin derivative, proceeds very efficiently between the borafluorene and various alkynes by simply mixing these two components. The second step is triggered by a one-electron oxidation of the borepin derivative, which results in the formation of a phenanthrene framework. When an excess amount of oxidant is used in the second step, the phenanthrene derivatives can be further transformed in situ to afford dibenzo[g,p]chrysene derivatives. The results presented herein will substantially expand the understanding of main group chemistry and provide a powerful synthetic tool for the construction of a wide variety of extended π-conjugated systems. PMID:27581519

  11. Modelling and simulation of a transketolase mediated reaction: Sensitivity analysis of kinetic parameters

    DEFF Research Database (Denmark)

    Sayar, N.A.; Chen, B.H.; Lye, G.J.

    2009-01-01

    In this paper we have used a proposed mathematical model, describing the carbon-carbon bond format ion reaction between beta-hydroxypyruvate and glycolaldehyde to synthesise L-erythrulose, catalysed by the enzyme transketolase, for the analysis of the sensitivity of the process to its kinetic par....... (C) 2009 Elsevier B.V. All rights reserved....

  12. Silver(Ⅰ)-mediated reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides: Unexpected formation of vinyl sulfones

    Institute of Scientific and Technical Information of China (English)

    Gui Sheng Deng; Teng Fei Sun

    2012-01-01

    A novel reaction of trimethylsilylated arylacetylenes with sulfonyl chlorides was performed in the presence of silver nitrate or triflate.Conjugated vinyl sulfones as dramatic products were obtained in moderate yields and with Z-selectivity.A free radical mechanism has been proposed to account for the formation of the products.

  13. Total Synthesis of the Antimicrotubule Agent (+)-Discodermolide Using Boron-Mediated Aldol Reactions of Chiral Ketones.

    Science.gov (United States)

    Paterson; Florence; Gerlach; Scott

    2000-01-01

    With a similar mechanism of action to taxol, the title compound 1 is a particularly promising candidate for development in cancer chemotherapy. This efficient synthesis, based on stereocontrolled aldol reactions, should help to overcome the scarce natural supply of 1 from the rare sponge source.

  14. Triflic Anhydride-Mediated Beckmann Rearrangement Reaction of Β-Oximyl Amides: Access to 5-Iminooxazolines

    Indian Academy of Sciences (India)

    MANGFEI YU; QIAN ZHANG; JIA WANG; PENG HUANG; PENGFEI YAN; RUI ZHANG; DEWEN DONG

    2016-06-01

    Facile and efficient synthesis of 5-iminooxazolines fromΑ, Α-disubstituted Β-oximyl amidesmediated by triflic anhydride $(Tf_{2}O)$ in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) indichloromethane at room temperature is developed, and a mechanism involving tandem Beckmann rearrangementand intramolecular cyclization reaction is proposed.

  15. Assessment of viability and acrosomal status of Asian elephant (Elephas maximus sperm after treatment with calcium ionophore and heparin

    Directory of Open Access Journals (Sweden)

    M. Sa-ardrit

    2009-05-01

    Full Text Available Knowledge about the acrosomal status of Asian elephant (Elephas maximus sperm is extremely limited. The objective of this study was to evaluate the viability and acrosomal status of Asian elephant sperm following induction by calcium ionophore and heparin using propidium iodide (PI and fluorescein isothiocyanate conjugated peanut agglutinin (FITC-PNA. Semen samples were collected from elephant bulls by manual stimulation. Semen was diluted with extender, cooled to 4°C and transported to a laboratory for the experiment. Sperm cells were incubated in modified Tyrode's medium containing either 1mM calcium ionophore or 10 mg/mℓ heparin for 5 h at 39°C. Sperm recovered at the onset (0 h, 1, 2, 3, 4 and 5 h of incubation were simultaneously assessed for the viability and acrosomal status using dual staining of FITC-PNA and PI. Results were confirmed by transmission electron microscopy. A progressive increase in the proportion of live-acrosome reacted sperm was observed within 3 h of incubation in both treatment groups which slightly decreased at 4 to5 h of incubation. At 1 to 3 h of incubation, the percentage of live-acrosome reacted sperm induced by calcium ionophore was higher (P < 0.05 than those induced by heparin and the control. However, there were no statistical differences at 4 to 5 h of incubation. A progressive reduction of the percentage of motile sperm was observed in the control as well as both treatment groups. Sperm motility decreased sharply when they were incubated in calcium ionophore compared with incubation in heparin and control groups. These results indicate that the occurrence of live-acrosome reacted sperm in the Asian elephant was induced by calcium ionophore at a rate higher than that induced by heparin.

  16. Sexual reactions in Mortierellales are mediated by the trisporic acid system.

    Science.gov (United States)

    Schimek, Christine; Kleppe, Kathrin; Saleem, Abdel-Rahman; Voigt, Kerstin; Burmester, Anke; Wöstemeyer, Johannes

    2003-06-01

    Several species of Mortierella (Mortierellales, Zygomycota) were examined for substances regulating their sexual reactions. Compounds isolated from both mated and single growing Mortierella strains were purified by thin layer chromatography. Some of these compounds showed UV absorbance-characteristics similar to those of trisporoids, a group of compounds involved in sexual regulation in Mucorales. A compound with a 4-dihydromethyltrisporate-like absorbance spectrum was detected. To test for the interspecific sexual responses typically induced by trisporoids, the compounds extracted from Mortierella spp. were tested against the Mucorales Mucor mucedo and Phycomyces blakesleeanus and were found to induce sexual reactions in both tester strains. A gene encoding 4-dihydromethyltrisporate dehydrogenase was identified in several Mortierella species and the activity of the gene product was shown using a histochemical assay. We suggest that the regulation of sexual processes by trisporoids is common to both Mucorales and Mortierellales and may be more widespread within the Zygomycota.

  17. Contribution of basophils to cutaneous immune reactions and Th2-mediated allergic responses

    Directory of Open Access Journals (Sweden)

    Atsushi eOtsuka

    2015-08-01

    Full Text Available Basophils are potent effector cells of innate immunity and also play a role in T helper 2 (Th2-mediated allergic responses. But, although their in vitro functions are well studied, their in vivo functions remain largely unknown. However, several mouse models of basophil depletion have recently been developed and used to investigate basophil functions. For example, in a croton oil-induced model of irritant contact dermatitis in conditionally basophil-depleted transgenic mice, we found that basophils rapidly infiltrate inflamed skin and subsequently induce infiltration of eosinophils. We also showed that basophils induce Th2 skewing upon epicutaneous sensitization with various haptens and peptide antigens. Intriguingly, basophils also promoted Th2 polarization upon protein antigen exposure in the presence of dendritic cells (DCs. The dermal DC subset associated with Th2 skewing was recently identified as CD301b+ DC. Such studies with basophil-deficient mouse models have significantly improved our understanding of the mechanisms involved in human immune-related diseases. In this review, we will focus on the relative contribution of basophils and DCs to Th2-mediated allergic responses.

  18. Fixed-charge phosphine ligands to explore gas-phase coinage metal-mediated decarboxylation reactions.

    Science.gov (United States)

    Vikse, Krista; Khairallah, George N; McIndoe, J Scott; O'Hair, Richard A J

    2013-05-14

    A combination of multistage mass spectrometry experiments and density functional theory (DFT) calculations were used to examine the decarboxylation reactions of a series of metal carboxylate complexes bearing a fixed-charge phosphine ligand, [(O3SC6H4)(C6H5)2PM(I)O2CR](-) (M = Cu, Ag, Au; R = Me, Et, benzyl, Ph). Collision-induced dissociation (CID) of these complexes using an LTQ linear ion mass spectrometer results in three main classes of reactions being observed: (1) decarboxylation; (2) loss of the phosphine ligand; (3) loss of carboxylic acid. The gas-phase unimolecular chemistry of the resultant decarboxylated organometallic ions, [(O3SC6H4)(C6H5)2PM(I)R](-), were also explored using CID experiments, and fragment primarily via loss of the phosphine ligand. Energy-resolved CID experiments on [(O3SC6H4)(C6H5)2PM(I)O2CR](-) (M = Cu, Ag, Au; R = Me, Et, benzyl, Ph) using a Q-TOF mass spectrometer were performed to gain a more detailed understanding of the factors influencing coinage metal-catalyzed decarboxylation and DFT calculations on the major fragmentation pathways aided in interpretation of the experimental results. Key findings are that: (1) the energy required for loss of the phosphine ligand follows the order Ag phosphine ligand on decarboxylation is also considered in comparison with previous studies on metal carboxylates that do not contain a phosphine ligand.

  19. Structure-Based Mechanism for Early PLP-Mediated Steps of Rabbit Cytosolic Serine Hydroxymethyltransferase Reaction

    Directory of Open Access Journals (Sweden)

    Martino L. Di Salvo

    2013-01-01

    Full Text Available Serine hydroxymethyltransferase catalyzes the reversible interconversion of L-serine and glycine with transfer of one-carbon groups to and from tetrahydrofolate. Active site residue Thr254 is known to be involved in the transaldimination reaction, a crucial step in the catalytic mechanism of all pyridoxal 5′-phosphate- (PLP- dependent enzymes, which determines binding of substrates and release of products. In order to better understand the role of Thr254, we have expressed, characterized, and determined the crystal structures of rabbit cytosolic serine hydroxymethyltransferase T254A and T254C mutant forms, in the absence and presence of substrates. These mutants accumulate a kinetically stable gem-diamine intermediate, and their crystal structures show differences in the active site with respect to wild type. The kinetic and crystallographic data acquired with mutant enzymes permit us to infer that conversion of gem-diamine to external aldimine is significantly slowed because intermediates are trapped into an anomalous position by a misorientation of the PLP ring, and a new energy barrier hampers the transaldimination reaction. This barrier likely arises from the loss of the stabilizing hydrogen bond between the hydroxymethyl group of Thr254 and the ε-amino group of active site Lys257, which stabilizes the external aldimine intermediate in wild type SHMTs.

  20. Mangiferin antagonizes TNF-α-mediated inflammatory reaction and protects against dermatitis in a mice model.

    Science.gov (United States)

    Zhao, Yunpeng; Wang, Wenhan; Wu, Xihai; Ma, Xiaoqian; Qu, Ruize; Chen, Xiaomin; Liu, Chenghao; Liu, Yaoge; Wang, Xiaokai; Yan, Pengcheng; Zhang, Hao; Pan, Jingrui; Li, Weiwei

    2017-04-01

    This study aimed to investigate whether mangiferin played a protective role in a well-established dermatitis mouse model and tumor necrosis factor alpha (TNF-α)-induced RAW264.7 macrophages. Contact dermatitis is an inflammatory skin disease in the clinic, while its underlying mechanism still remains to be elucidated. Mangiferin, 1,3,6,7-tetrahydroxyxanthone-C2-β-d-glucoside (C-glucosyl xanthone), a natural antioxidant that was reported to inhibit inflammatory reactions, has been recently proved to be a potential therapy for inflammation. As a result, the oxazolone-induced dermatitis mice models were established to explore whether mangiferin has an anti-inflammatory role in vivo. The phosphate-buffered saline treatment groups showed emblematic skin inflammation, whereas the administration of mangiferin obviously inhibited dermatitis in the mice models. Furthermore, exogenous mangiferin alleviated the inflammatory reaction in TNF-α-induced macrophages by suppressing the production of inflammation- and oxidative stress-associated molecules. Also, mangiferin treatment repressed the activation of nuclear factor-kappaB signaling pathway. To sum up, mangiferin could provide a new target for the therapy and prevention of skin inflammation.

  1. Transition from spiral waves to defect-mediated turbulence induced by gradient effects in a reaction-diffusion system

    Science.gov (United States)

    Zhang, Chunxia; Zhang, Hong; Ouyang, Qi; Hu, Bambi; Gunaratne, Gemunu H.

    2003-09-01

    The transition from spiral waves to defect-mediated turbulence was studied in a spatial open reactor using Belousov-Zhabotinsky reaction. The experimental results show a new mechanism of the transition from spirals to spatiotemporal chaos, in which the gradient effects in the three-dimensional system are essential. The transition scenario consists of two stages: first, the effects of gradients in the third dimension cause a splitting of the spiral tip and a deletion of certain wave segments, generating new wave sources; second, the waves sent by the new wave sources undergo a backfire instability, and the back waves are laterally unstable. As a result, defects are automatically generated and fill all over the system. The result of numerical simulation using the FitzHugh-Nagumo model essentially agrees with the experimental observation.

  2. Single primer-mediated circular polymerase chain reaction for hairpin DNA cloning and plasmid editing.

    Science.gov (United States)

    Huang, Jiansheng; Khan, Inamullah; Liu, Rui; Yang, Yan; Zhu, Naishuo

    2016-05-01

    We developed and validated a universal polymerase chain reaction (PCR) method, single primer circular (SPC)-PCR, using single primer to simultaneously insert and amplify a short hairpin sequence into a vector with a high success rate. In this method, the hairpin structure is divided into two parts and fused into a vector by PCR. Then, a single primer is used to cyclize the chimera into a mature short hairpin RNA (shRNA) expression vector. It is not biased by loop length or palindromic structures. Six hairpin DNAs with short 4-nucleotide loops were successfully cloned. Moreover, SPC-PCR was also applied to plasmid editing within 3 h with a success rate higher than 95%.

  3. Bacterial discrimination by means of a universal array approach mediated by LDR (ligase detection reaction

    Directory of Open Access Journals (Sweden)

    Consolandi Clarissa

    2002-09-01

    Full Text Available Abstract Background PCR amplification of bacterial 16S rRNA genes provides the most comprehensive and flexible means of sampling bacterial communities. Sequence analysis of these cloned fragments can provide a qualitative and quantitative insight of the microbial population under scrutiny although this approach is not suited to large-scale screenings. Other methods, such as denaturing gradient gel electrophoresis, heteroduplex or terminal restriction fragment analysis are rapid and therefore amenable to field-scale experiments. A very recent addition to these analytical tools is represented by microarray technology. Results Here we present our results using a Universal DNA Microarray approach as an analytical tool for bacterial discrimination. The proposed procedure is based on the properties of the DNA ligation reaction and requires the design of two probes specific for each target sequence. One oligo carries a fluorescent label and the other a unique sequence (cZipCode or complementary ZipCode which identifies a ligation product. Ligated fragments, obtained in presence of a proper template (a PCR amplified fragment of the 16s rRNA gene contain either the fluorescent label or the unique sequence and therefore are addressed to the location on the microarray where the ZipCode sequence has been spotted. Such an array is therefore "Universal" being unrelated to a specific molecular analysis. Here we present the design of probes specific for some groups of bacteria and their application to bacterial diagnostics. Conclusions The combined use of selective probes, ligation reaction and the Universal Array approach yielded an analytical procedure with a good power of discrimination among bacteria.

  4. Molecular Detection of Methicillin-Resistant Staphylococcus aureus by Non-Protein Coding RNA-Mediated Monoplex Polymerase Chain Reaction

    Science.gov (United States)

    Soo Yean, Cheryl Yeap; Selva Raju, Kishanraj; Xavier, Rathinam; Subramaniam, Sreeramanan; Gopinath, Subash C. B.; Chinni, Suresh V.

    2016-01-01

    Non-protein coding RNA (npcRNA) is a functional RNA molecule that is not translated into a protein. Bacterial npcRNAs are structurally diversified molecules, typically 50–200 nucleotides in length. They play a crucial physiological role in cellular networking, including stress responses, replication and bacterial virulence. In this study, by using an identified npcRNA gene (Sau-02) in Methicillin-resistant Staphylococcus aureus (MRSA), we identified the Gram-positive bacteria S. aureus. A Sau-02-mediated monoplex Polymerase Chain Reaction (PCR) assay was designed that displayed high sensitivity and specificity. Fourteen different bacteria and 18 S. aureus strains were tested, and the results showed that the Sau-02 gene is specific to S. aureus. The detection limit was tested against genomic DNA from MRSA and was found to be ~10 genome copies. Further, the detection was extended to whole-cell MRSA detection, and we reached the detection limit with two bacteria. The monoplex PCR assay demonstrated in this study is a novel detection method that can replicate other npcRNA-mediated detection assays. PMID:27367909

  5. Influence of Boar and Semen Parameters on Motility and Acrosome Integrity in Liquid Boar Semen Stored for Five Days

    Directory of Open Access Journals (Sweden)

    Sehested E

    2002-03-01

    Full Text Available Ninety ejaculates from a total of 76 AI boars were extended in Beltsville Thawing Solution (BTS. Boar identity, breed, weight of the ejaculate and sperm concentration were registered. Motility and acrosome integrity were assessed after storage at 16–18°C for 6, 30, 54, 78, and 102 h. Storage time had a significant influence on both motility (p

  6. Transmission electron microscopic observations of acrosome and head abnormalities in impala (Aepyceros melampus sperm from the Kruger National Park

    Directory of Open Access Journals (Sweden)

    D.J. Ackerman

    1997-01-01

    Full Text Available Sperm morphological features play an important role in semen evaluation. Exposure to a variety of chemical compounds, especially environmental endocrine disrupters, elicit abnormalities in sperm of certain species. Baseline data on ultrastructure of normal sperm as well as abnormalities observed concomitantly, are required before causal links between such substances and abnormalities can be established. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy to document normal sperm features and abnormalities. The following abnormalities of the acrosome and sperm head were documented from micrographs: Loose acrosome in various stages of disintegration, lip forming of the acrosome; bizarre head, crater defect, poor condensation of the nucleus and the Dag defect. The observed abnormalities were very similar to those reported for other members of the Bovidae. Different forms of a hollow sphere, formed by the nucleus and covered by an abnormal acrosome have not previously been described for other species.

  7. Reaction kinetic model of the surface-mediated formation of PCDD/F from pyrolysis of 2-chlorophenol on a CuP/Silica suface

    Energy Technology Data Exchange (ETDEWEB)

    Lomnicki, S.; Khachatryan, L.; Dellinger, B. [Louisiana State Univ., Baton Rouge (United States). Dept. of Chemistry

    2004-09-15

    One of the major challenges in developing predictive models of the surface mediated pollutant formation and fuel combustion is the construction of reliable reaction kinetic mechanisms and models. While the homogeneous, gas-phase chemistry of various light fuels such as hydrogen and methane is relatively well-known large uncertainties exist in the reaction paths of surface mediated reaction mechanisms for even these very simple species. To date, no detailed kinetic consideration of the surface mechanisms of formation of complex organics such as PCDD/F have been developed. In addition to the complexity of the mechanism, a major difficulty is the lack of reaction kinetic parameters (pre-exponential factor and activation energy) of surface reactions, Consequently, numerical studies of the surface-mediated formation of PCDD/F have often been incorporated only a few reactions. We report the development of a numerical multiple-step surface model based on experimental data of surface mediated (5% CuO/SiO2) conversion of 2-monochlorphenol (2-MCP) to PCDD/F under pyrolytic or oxidative conditions. A reaction kinetic model of the catalytic conversion of 2-MCP on the copper oxide catalyst under pyrolytic conditions was developed based on a detailed multistep surface reaction mechanism developed in our laboratory. The performance of the chemical model is assessed by comparing the numerical predictions with experimental measurements. SURFACE CHEMKIN (version 3.7.1) software was used for modeling. Our results confirm the validity of previously published mechanism of the reaction and provides new insight concerning the formation of PCDD/F formation in combustion processes. This model successfully explains the high yields of PCDD/F at low temperatures that cannot be explained using a purely gas-phase mode.

  8. Micellar-mediated extractive spectrophotometric determination of hydrogen sulfide/sulfide through Prussian Blue reaction: application to environmental samples.

    Science.gov (United States)

    Pandurangappa, Malingappa; Samrat, Devaramani

    2010-01-01

    A sensitive surfactant-mediated extractive spectrophotometric method has been developed, based on the reaction of ferric iron with sulfide to form ferrous iron and its subsequent reaction with ferricyanide to form Prussian Blue, to quantify trace levels of hydrogen sulfide/sulfide in environmental samples. The method obeys Beer's law in the concentration range 2-10 microg of sulfide in 25 mL of aqueous phase with molar absorptivity (epsilon) of 3.92 x 10(4) L mol(-1) cm(-1). The colored species has been extracted into isoamyl acetate in the presence of a cationic surfactant i.e. cetylpyridinium chloride, to enhance the sensitivity of the method with epsilon value 5.2 x 10(4) L mol(-1) cm(-1). The relative standard deviation has been found to be 0.69% for 10 determinations at 4 microg of sulfide and the limit of detection was 0.009 microg mL(-1). The interference from common anions and cations has been studied. The proposed method has been applied to the determination of residual hydrogen sulfide in the laboratory fume hood as well as ambient atmospheric hydrogen sulfide in the vicinity of open sewer lines after fixing the analyte in ionic form using suitable trapping medium.

  9. The Effect of the Negotiator's Social Power as a Function of the Counterpart's Emotional Reactions in a Computer Mediated Negotiation

    Directory of Open Access Journals (Sweden)

    Shlomo Hareli

    2013-11-01

    Full Text Available A negotiator’s own power and their counterpart’s emotional reaction to the negotiation both influence the outcome of negotiations. The present research addressed the question of their relative importance. On one hand, social power should be potent regardless of the other’s emotions. On the other hand, the counterpart’s emotional reactions inform about the ongoing state of the negotiation, and as such are more diagnostic than the more distal power cue. In a simulated computer mediated negotiation, 248 participants assumed the role of a vendor of computerized avionics test equipment and their objective was to negotiate the price, the warranty period, and the number of software updates that the buyer will receive free of charge. Participants negotiated the sale after being primed with either high or low power or not primed at all (control condition. They received information that their counterpart was either happy or angry or emotionally neutral. The findings showed that even though power was an important factor at the start of negotiations, the informative value of emotion information took precedence over time. This implies that emotional information may erase any advantage that counterparts have in a negotiation thanks to their higher social power.

  10. The Modification of Cellulosic Surface with Fatty Acids via Plasma Mediated Reactions

    Science.gov (United States)

    Nada, Ahmed Ali Ahmed

    Much attention has been paid recently to understand the healing process made by the human body, in order to develop new approaches for promoting healing. The wound healing process includes four main phases, namely, hemostatic, inflammatory, proliferation, and remodeling, which take place successively. The human body can provide all the requirements of the healing process in normal wounds, unless there is a kind of deficiency of the skin function or massive fluid losses of vast wounds. Therefore, wound care of non-healing wounds has recently been the growing concern of many applications. The goal of this work is to explore the development of a new cellulose-based wound dressing composite that contain or release wound healing agents attained via dry textile chemical finishing techniques (thermal curing-plasma treatment). The synthesis of different wound healing agents derived from fatty acids and attached chemically to cellulose or even delivered through cyclodextrine modified cellulose are reported in this work. First, free fatty acids, which are obtained from commercial vegetable oils, were identified as wound healing agents. Many of these free acids are known to bind with and deactivate the proteases associated with inflammation at a wound site. Linoleic acid is extracted from commercial products of safflower seed oil while ricinoleic acid is obtained from castor oil. Conjugated linoleic acid was synthesized. Un-conjugated linoleic acid was used to prepare two derivatives namely linoleic azide and allylic ketone of linoleic acid. Different cellulose derivatives such as cellulose peroxide, iododeoxycellulose and cellulose diazonium salt in different degree of substitutions were synthesized in order to facilitate the free radical reaction with the fatty acid derivatives. New modified cellulosic products were synthesized by reacting the cellulosic and the linoleic acid derivatives via thermal or plasma technique and characterized by FT-IR ATR, the wettability test

  11. Mechanochemical solid-state synthesis of 2-aminothiazoles, quinoxalines and benzoylbenzofurans from ketones by one-pot sequential acid- and base-mediated reactions.

    Science.gov (United States)

    Nagarajaiah, Honnappa; Mishra, Abhaya Kumar; Moorthy, Jarugu Narasimha

    2016-04-26

    α-Chloroketones - obtained by the atom-economical chlorination of ketones with trichloroisocyanuric acid (TCCA) in the presence of p-TSA under ball-milling conditions - were set up for a sequential base-mediated condensation reaction with thiourea/thiosemicarbazides, o-phenylenediamine and salicylaldehyde to afford 2-aminothiazoles, 2-hydrazinylthiazoles, quinoxalines and benzoylbenzofurans, respectively, in respectable yields. The viability of one-pot sequential acid- and base-mediated reactions in the solid state under ball-milling conditions is thus demonstrated.

  12. Manchette-acrosome disorders during spermiogenesis and low efficiency of seminiferous tubules in hypercholesterolemic rabbit model

    Science.gov (United States)

    Simón, Layla; Funes, Abi K.; Yapur, Martín A.; Cabrillana, María E.; Monclus, María A.; Boarelli, Paola V.; Vincenti, Amanda E.

    2017-01-01

    Hypercholesterolemia is a marker for several adult chronic diseases. Recently we demonstrated that sub/infertility is also associated to Hypercholesterolemia in rabbits. Seminal alterations included: abnormal sperm morphology, decreased sperm number and declined percentage of motile sperm, among others. In this work, our objective was to evaluate the effects of hypercholesterolemia on testicular efficiency and spermiogenesis, as the latter are directly related to sperm number and morphology respectively. Tubular efficiency was determined by comparing total number of spermatogenic cells with each cell type within the proliferation/differentiation compartments. We found lower testicular efficiency related to both a decrease in spermatogonial cells and an increase in germ cell apoptosis in hypercholesterolemic rabbits. On the other hand, spermiogenesis–the last step of spermatogenesis involved in sperm shaping–was detaily analyzed, particularly the acrosome-nucleus-manchette complex. The manchette is a microtubular-based temporary structure responsible in sperm cell elongation. We analyzed the contribution of actin filaments and raft microdomains in the arrangement of the manchette. Under fluorescence microscopy, spermatocyte to sperm cell development was followed in cells isolated from V to VIII tubular stages. In cells from hypercholesterolemic rabbits, abnormal development of acrosome, nucleus and inaccurate tail implantation were associated with actin–alpha-tubulin–GM1 sphingolipid altered distribution. Morphological alterations were also observed at electron microscopy. We demonstrated for the first time that GM1-enriched microdomains together with actin filaments and microtubules are involved in allowing the correct anchoring of the manchette complex. In conclusion, cholesterol enriched diets promote male fertility alterations by affecting critical steps in sperm development: spermatogenesis and spermiogenesis. It was also demonstrated that

  13. Polymerase chain reaction-mediated characterization of molds belonging to the Aspergillus flavus group and detection of Aspergillus parasiticus in peanut kernels by a multiplex polymerase chain reaction.

    Science.gov (United States)

    Chen, Ruey-Shyang; Tsay, Jwu-Guh; Huang, Yu-Fen; Chiou, Robin Y Y

    2002-05-01

    The Aspergillus flavus group covers species of A. flavus and Aspergillus parasiticus as aflatoxin producers and Aspergillus oryzae and Aspergillus sojae as koji molds. Genetic similarity among these species is high, and aflatoxin production of a culture may be affected by cultivation conditions and substrate composition. Therefore, a polymerase chain reaction (PCR)-mediated method of detecting the aflatoxin-synthesizing genes to indicate the degree of risk a genotype has of being a phenotypic producer was demonstrated. In this study, 19 strains of the A. flavus group, including A. flavus, A. parasiticus, A. oryzae, A. sojae, and one Aspergillus niger, were subjected to PCR testing in an attempt to detect four genes, encoding for norsolorinic acid reductase (nor-1), versicolorin A dehydrogenase (ver-1), sterigmatocystin O-methyltransferase (omt-1), and a regulatory protein (apa-2), involved in aflatoxin biosynthesis. Concurrently, the strains were cultivated in yeast-malt (YM) broth for aflatoxin detection. Fifteen strains were shown to possess the four target DNA fragments. With regard to aflatoxigenicity, all seven aflatoxigenic strains possessed the four DNA fragments, and five strains bearing less than the four DNA fragments did not produce aflatoxin. When peanut kernels were artificially contaminated with A. parasiticus and A. niger for 7 days, the contaminant DNA was extractable from a piece of cotyledon (ca. 100 mg), and when subjected to multiplex PCR testing using the four pairs of primers coding for the above genes, they were successfully detected. The target DNA fragments were detected in the kernels infected with A. parasiticus, and none was detected in the sound (uninoculated) kernels or in the kernels infected with A. niger.

  14. Ubiquitin-activating enzyme (UBA1) is required for sperm capacitation, acrosomal exocytosis and sperm-egg coat penetration during porcine fertilization.

    Science.gov (United States)

    Yi, Y-J; Zimmerman, S W; Manandhar, G; Odhiambo, J F; Kennedy, C; Jonáková, V; Maňásková-Postlerová, P; Sutovsky, M; Park, C-S; Sutovsky, P

    2012-04-01

    Protein ubiquitination is a stable, covalent post-translational modification that alters protein activity and/or targets proteins for proteolysis by the 26S proteasome. The E1-type ubiquitin-activating enzyme (UBA1) is responsible for ubiquitin activation, the initial step of ubiquitin-protein ligation. Proteasomal proteolysis of ubiquitinated spermatozoa and oocyte proteins occurs during mammalian fertilization, particularly at the site of sperm acrosome contact with oocyte zona pellucida. However, it is not clear whether the substrates are solely proteins ubiquitinated during gametogenesis or if de novo ubiquitination also occurs during fertilization supported by ubiquitin-activating and -conjugating enzymes present in the sperm acrosome. Along this line of inquiry, UBA1 was detected in boar sperm-acrosomal extracts by Western blotting (WB). Immunofluorescence revealed accumulation of UBA1 in the nuclei of spermatogonia, spermatocytes and spermatids, and in the acrosomal caps of round and elongating spermatids. Thiol ester assays utilizing biotinylated ubiquitin and isolated sperm acrosomes confirmed the enzymatic activity of the resident UBA1. A specific UBA1 inhibitor, PYR-41, altered the remodelling of the outer acrosomal membrane (OAM) during sperm capacitation, monitored using flow cytometry of fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA). Although viable and motile, the spermatozoa capacitated in the presence of PYR-41, showed significantly reduced fertilization rates during in vitro fertilization (IVF; p sperm capacitation and acrosomal function during fertilization.

  15. Eicosanoids mediate nodulation reactions to bacterial Escherichia coli K 12 infections in larvae of the oriental blowfly,Chrysomya megacephala

    Institute of Scientific and Technical Information of China (English)

    Bing Chen; Yong Wang; Fen Zhu; Chao-Liang Lei

    2009-01-01

    Nodulation is the predominant cellular defense reaction to bacterial challenges in insects.In this study,third instar larvae of Chrysomya megacephala were injected with bacteria,Escherichia coli K 12 (10~6 CFU/mL,2μL),immediately prior to injection of inhibitors of eicosanoid biosynthesis,which sharply reduced nodulation response.Test larvae were treated with specific inhibitors of phospholipase A_2 (dexamethasone),cyclooxygenase (indomethacin,ibuprofen and piroxicam),dual cyclo-oxygenase/lipoxygenase (phenidone) and lipoxygenase (esculetin) and these reduced nodulation except esculetin.The influence of bacteria was obvious within 2 h of injection (5 nodules/larva),and increased to a maximum after 8 h (with 15 nodules/larva),and then significantly reduced over 24 h (9 nodules/larva).The inhibitory influence of dexamethasone was apparent within 2 h of injection (4 vs.5 nodules/larva),and nodulation was significantly reduced,compared to control,over 24 h (5 vs.8 nodules/larva).Increased dosages of ibuprofen,indomethacin,piroxicam and phenidone led to decreased numbers of nodules.Nodules continued to exist during the pupal stage.However,the effects of dexamethasone were reversed by treating bacteria-injected insects with an eicosanoid-precursor polyunsaturated fatty acid,arachidonic acid.These findings approved our view that eicosanoid can mediate cellular defense mechanisms in response to bacterial infections in another Dipteran insect C.megacephala.

  16. Kinetic studies on surface-mediated activation of bovine factor XII and prekallikrein. Effects of kaolin and high-Mr kininogen on the activation reactions.

    Science.gov (United States)

    Sugo, T; Kato, H; Iwanaga, S; Takada, K; Sakakibara, S

    1985-01-02

    The kaolin-mediated reciprocal activation of bovine factor XII and prekallikrein was divided into the following two reactions: the activation of factor XII by plasma kallikrein (reaction 1) and the activation of prekallikrein by factor XIIa (reaction 2). The effects of high-Mr kininogen and kaolin surface on the kinetics of these activation reactions were studied. High-Mr kininogen markedly enhanced the rate of reactions 1 and 2 in the presence of kaolin, and the enhancements were highly dependent on the concentrations of the protein cofactor and amount of kaolin surface. For the activation of factor XII by plasma kallikrein (reaction 1), high-Mr kininogen was required when a low concentration of factor XII and kaolin was used. The molar ratio of the protein cofactor to factor XII for optimal activation was found to be approximately 1:1. The apparent Km value and the kcat/Km value for plasma kallikrein on factor XII were calculated to be 4 nM and 5.2 X 10(7) s-1 X M-1, respectively. The activation of prekallikrein by factor XIIa, (reaction 2) proceeded even in the absence of high-Mr kininogen and kaolin. The addition of the protein cofactor and surface to the reaction mixture remarkably accelerated the reaction, and the apparent Km value for factor XIIa on prekallikrein was reduced from 1 microM to 40 nM. Moreover, the kcat/Km value was altered from 7.3 X 10(4) to 1.1 X 10(6) s-1 X M-1). These results suggest that high-Mr kininogen accelerates the surface-mediated activation of factor XII and prekallikrein by enhancing the susceptibility of factor XII to plasma kallikrein, on the one hand, and the affinity of factor XIIa for prekallikrein, on the other hand. Kaolin may play an important role in the concentration and organization of these components on the negatively charged surface.

  17. Validation of non-fluorescent methods to reliably detect acrosomal and plasma membrane integrity of common marmoset (Callithrix jacchus) sperm.

    Science.gov (United States)

    Valle, R R; Valle, C M R; Nichi, M; Muniz, J A P C; Nayudu, P L; Guimarães, M A B V

    2008-07-01

    Simple, rapid and stable sperm evaluation methods which have been optimized for common marmoset (Callithrix jacchus) are critical for studies involving collection and evaluation of sperm in the field. This is particularly important for new species groups such as Callitrichidae where the sperm have been little studied. Of this family, C. jacchus is the best known, and has been chosen as a model species for other members of the genus Callithrix. The fundamental evaluation parameters for sperm of any species are viability and acrosomal status. Semen samples were collected by penile vibratory stimulation. To evaluate sperm plasma membrane integrity, Eosin-Nigrosin was tested here for the common marmoset sperm to be used under field conditions. Further, a non-fluorescent stain for acrosome, the "Simple" stain, developed for domestic and wild cats, was tested on common marmoset sperm. This was compared with a fluorescent staining, Fluorescein isothiocyanate-Pisum sativum agglutinin (FITC-PSA), routinely used and validated for common marmoset at the German Primate Centre to evaluate acrosomal integrity. Results obtained with the "Simple" stain showed a marked differentiation between sperm with intact and non-intact acrosome both with and without ionophore treatment and closely correlated with results obtained with FITC-PSA. Temperature had no effect on the results with the "Simple" stain and the complete processing is simple enough to be carried out under field conditions. These findings indicated that the "Simple" stain and Eosin-Nigrosin provide rapid and accurate results for C. jacchus sperm and that those methods can be reliably used as field tools for sperm evaluation for this species.

  18. Increased chromatin fragmentation and reduced acrosome integrity in spermatozoa of red deer from lead polluted sites.

    Science.gov (United States)

    Castellanos, Pilar; del Olmo, Enrique; Fernández-Santos, M Rocío; Rodríguez-Estival, Jaime; Garde, J Julián; Mateo, Rafael

    2015-02-01

    Vertebrates are constantly exposed to a diffuse pollution of heavy metals existing in the environment, but in some cases, the proximity to emission sources like mining activity increases the risk of developing adverse effects of these pollutants. Here we have studied lead (Pb) levels in spermatozoa and testis, and chromatin damage and levels of endogenous antioxidant activity in spermatozoa of red deer (Cervus elaphus) from a Pb mining area (n=37) and a control area (n=26). Deer from the Pb-polluted area showed higher Pb levels in testis parenchyma, epididymal cauda and spermatozoa, lower values of acrosome integrity, higher activity of glutathione peroxidase (GPx) and higher values of DNA fragmentation (X-DFI) and stainability (HDS) in sperm than in the control area. These results indicate that mining pollution can produce damage on chromatin and membrane spermatozoa in wildlife. The study of chromatin fragmentation has not been studied before in spermatozoa of wildlife species, and the sperm chromatin structure assay (SCSA) has been revealed as a successful tool for this purpose in species in which the amount of sperm that can be collected is very limited.

  19. 2-Hydroxy-3-methoxybenzoic acid attenuates mast cell-mediated allergic reaction in mice via modulation of the FcεRI signaling pathway

    OpenAIRE

    Kim, Yeon-Yong; Je, In-Gyu; Kim, Min Jong; Kang, Byeong-Cheol; Choi, Young-Ae; Baek, Moon-Chang; Lee, Byungheon; Choi, Jin Kyeong; Park, Hae Ran; Shin, Tae-Yong; Lee, Soyoung; Yoon, Seung-Bin; Lee, Sang-Rae; Khang, Dongwoo; Kim, Sang-Hyun

    2016-01-01

    Mast cells are important effector cells in immunoglobulin (Ig) E-mediated allergic reactions such as asthma, atopic dermatitis and rhinitis. Vanillic acid, a natural product, has shown anti-oxidant and anti-inflammatory activities. In the present study, we investigated the anti-allergic inflammatory effects of ortho-vanillic acid (2-hydroxy-3-methoxybenzoic acid, o-VA) that was a derivative of vanillic acid isolated from Amomum xanthioides. In mouse anaphylaxis models, oral administration of ...

  20. Dynamic pathways to mediate reactions buried in thermal fluctuations. I. Time-dependent normal form theory for multidimensional Langevin equation.

    Science.gov (United States)

    Kawai, Shinnosuke; Komatsuzaki, Tamiki

    2009-12-14

    We present a novel theory which enables us to explore the mechanism of reaction selectivity and robust functions in complex systems persisting under thermal fluctuation. The theory constructs a nonlinear coordinate transformation so that the equation of motion for the new reaction coordinate is independent of the other nonreactive coordinates in the presence of thermal fluctuation. In this article we suppose that reacting systems subject to thermal noise are described by a multidimensional Langevin equation without a priori assumption for the form of potential. The reaction coordinate is composed not only of all the coordinates and velocities associated with the system (solute) but also of the random force exerted by the environment (solvent) with friction constants. The sign of the reaction coordinate at any instantaneous moment in the region of a saddle determines the fate of the reaction, i.e., whether the reaction will proceed through to the products or go back to the reactants. By assuming the statistical properties of the random force, one can know a priori a well-defined boundary of the reaction which separates the full position-velocity space in the saddle region into mainly reactive and mainly nonreactive regions even under thermal fluctuation. The analytical expression of the reaction coordinate provides the firm foundation on the mechanism of how and why reaction proceeds in thermal fluctuating environments.

  1. Osmotic tolerance limits and effects of cryoprotectants on the motility, plasma membrane integrity and acrosomal integrity of rat sperm.

    Science.gov (United States)

    Si, Wei; Benson, James D; Men, Hongsheng; Critser, John K

    2006-12-01

    Osmotic stress is an important factor that can result in cell damage during cryopreservation. The objectives of this study were to determine: (1) isosmotic sperm cell volume; (2) osmotically inactive volume; (3) osmotic tolerance limits of rat sperm; and (4) the effects of addition and removal of glycerol (Gly), ethylene glycol (EG), propylene glycol (PG) or dimethyl sulfoxide (Me(2)SO) on rat sperm function. Sperm from Fischer 344 and Sprague-Dawley rats were used in this study. An electronic particle counter was used to measure the cell volume of rat sperm. Computer-assisted sperm motility analysis and flow-cytometric analysis were used to assess sperm motility, plasma membrane and acrosomal integrity. The isosmotic sperm cell volumes of the two strains were 37.0+/-0.1 and 36.2+/-0.2 microm(3), respectively. Rat sperm behaved as linear osmometers from 260 to 450 mOsm, and the osmotically inactive sperm volumes of the two strains were 79.8+/-1.5% and 81.4+/-2.2%, respectively. Rat sperm have very limited osmotic tolerances. The sperm motility and the sperm plasma membranes of both strains were sensitive to anisosmotic treatments, but the acrosomes of both strains were more sensitive to hyposmotic than hyperosmotic conditions. The one-step addition and removal of Me(2)SO showed the most deleterious effect on rat sperm motility, plasma membrane integrity, and acrosomal integrity among the four cryoprotectants. These data characterizing rat sperm osmotic behavior, osmotic and cryoprotectant tolerance will be used to design cryopreservation protocols for rat sperm.

  2. Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

    Science.gov (United States)

    Engelen, Bernward; Panthöfer, Martin; Deiseroth, Hans-Jörg; Schlirf, Jens

    2016-01-01

    Summary A one-pot transformation, which involves the reaction of ketones with aldehydes in the presence of metal halides to furnish tetrahydro-2H-pyran-2,4-diols in a highly diastereoselective manner, is investigated thoroughly by experiments and computations. The reaction was also successfully implemented on a flow micro reactor system. PMID:27340472

  3. Production of Organic Grain Coatings by Surface-Mediated Reactions and the Consequences of This Process for Meteoritic Constituents

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha M.

    2011-01-01

    When hydrogen, nitrogen and CO are exposed to amorphous iron silicate surfaces at temperatures between 500 - 900K, a carbonaceous coating forms via Fischer-Tropsch type reactions. Under normal circumstances such a catalytic coating would impede or stop further reaction. However, we find that this coating is a better catalyst than the amorphous iron silicates that initiate these reactions. The formation of a self-perpetuating catalytic coating on grain surfaces could explain the rich deposits of macromolecular carbon found in primitive meteorites and would imply that protostellar nebulae should be rich in organic material. Many more experiments are needed to understand this chemical system and its application to protostellar nebulae.

  4. Pd/C-mediated dual C-C bond forming reaction in water: synthesis of 2,4-dialkynylquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Ellanki A.; Islam, Aminul; Venu, Bolla K. [Dr. Reddy' s Laboratories Limited, Hyderabad, Andhra Pradesh (India); Mukkanti, K. [JNT University, Hyderabad, Andhra Pradesh (India). Inst. of Science and Technology. Chemistry Division; Pal, Manojit, E-mail: manojitpal@rediffmail.co [Matrix Laboratories Ltd., Medak District, Andra Pradesh (India). New Drug Discovery. R and D Center

    2010-07-01

    Pd/C facilitated dual C-C bond forming reaction between 2,4-diiodoquinoline and terminal alkynes in water providing a practical and one-step synthesis of 2,4-dialkynylquinolines. A number of related quinoline derivatives were prepared in good to excellent yields using this water-based methodology. The use of other palladium catalysts and solvents was examined and the mechanism of the reaction has been discussed. (author)

  5. Inhibition of Hamster Sperm Acrosomal Enzyme by Gossypol is Closely Associated with the Decrease in Fertilization Capacity

    Institute of Scientific and Technical Information of China (English)

    YuanYu-ying; ShiQi-xian

    2005-01-01

    To elucidate the mechanism of sterility induced by gossypol,we studied the relationship between the activities of acrosomal enzymes and their fertilizing capacity in the hamster. The results showed that the ability of spermatozoa to penetrate into bovine cervical mucus,hyperactivated motility(HAM)and fertility in vivo were significantly inhibited when spermatozoa were exposed to gossypol (2.5μg-60μg/mL)for 15 min in vitro.Also,following administration of gossypol (12.5mg/kg/day)for 6 weeks,sperm motility,HAM and rate of fertilization in vitro by the hamster cauda epididymal spermatozoa were significantly decreased and the extracts of testis delayed dispersion of the cumulus oophorus cells,suggesting that hyaluronidase and other acrosomal enzymes might be inhibited by gossypol.In addition, acrosin and arylsulfatase activities were also markedly inhibited.These data show that the inhibition of acrosin and arylsulfatase activities is the main cause of gossypol-induced infertility.The inhibition was dependent upon gossypol dose and the duration of administration.Thus, the assay of acrosin and arylsulfatase activities may provide a useful tool for monitoring sterility induced by gossypol.

  6. Use of Cyclic Allylic Bromides in the Zinc–Mediated Aqueous Barbier–Grignard Reaction

    Directory of Open Access Journals (Sweden)

    Suzanne M. Perala

    2001-07-01

    Full Text Available The zinc–mediated aqueous Barbier–Grignard reaction of cyclic allylic bromide substrates with various aldehydes and ketones to afford homoallylic alcohols was investigated. Aromatic aldehydes and ketones afforded adducts in good yields (66–90% and with good diastereoselectivities. Non–aromatic aldehydes also reacted well under these conditions, but only poor yields were obtained with non–aromatic ketones. Regioselectivity was high when some substituted cyclic allylic bromides were investigated.

  7. Quantitative changes of Ricinus communis agglutinin I and Helix pomatia lectin binding sites in the acrosome of rat spermatozoa during epididymal transit.

    Science.gov (United States)

    Hermo, L; Winikoff, R; Kan, F W

    1992-09-01

    During passage through the epididymis, spermatozoa undergo a number of changes which result in their acquisition of fertility and motility. Some of the changes that occur include loss of the cytoplasmic droplet and changes in sperm morphology, metabolism and properties of the nucleus and plasma membrane. Changes have also been reported in the acrosomic system of mammalian spermatozoa during their transit through the epididymis. In the present study, the quantitative changes of the glycoconjugate content in the acrosome of rat spermatozoa were examined during their passage through the epididymis using lectin-colloidal gold cytochemistry. Various regions of the epididymis (initial segment, caput, corpus and cauda epididymidis) were fixed by perfusion with 1% or 2% glutaraldehyde buffered in sodium cacodylate (0.1 M), dehydrated in ethanol and embedded without osmication in Lowicryl K4M. Lectin-colloidal gold labeling was performed on thin sections using Ricinus communis agglutinin I (RCA I) or Helix pomatia lectin (HPL) to detect D-galactose- and N-acetyl-D-galactosamine-containing glycoconjugates, respectively. The labeling density over the acrosome of the acrosomic system was evaluated as the number of gold particles per microns 2 of profile area using a Zeiss MOP-3 image analyzer. The overall mean labeling densities over the acrosome of spermatozoa for each lectin was estimated from 4 rats and over the four distinct epididymal regions. The mean labeling density of the acrosome with RCA I and HPL showed a similar pattern along the epididymis, although RCA I revealed approximately twice as many gold particles per epididymal region. In either case, there was a significant decrease in the labeling density of the acrosome of spermatozoa between the initial segment or caput epididymidis and cauda epididymidis (p less than 0.01). A similar decrease was also noted between the initial segment and corpus epididymidis (p less than 0.01). No change was found between the

  8. A Triple-Stain Flow Cytometric Method to Assess Plasma- and Acrosome-Membrane Integrity of Cryopreserved Bovine Sperm Immediately after Thawing in Presence of Egg-Yolk Particles

    NARCIS (Netherlands)

    Nagy, S.; Jansen, J.; Topper, E.K.; Gadella, B.M.

    2003-01-01

    Simultaneously evaluating postthaw viability and acrosome integrity of spermatozoa by flow cytometry would provide a valuable testing tool in both research and routine work. In the present study, a new triple-stain combination was developed for the simultaneous evaluation of viability and acrosome i

  9. Study on the reactions of azo compounds with acyl halides mediated by Sm/TiCl4

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Amides can be obtained in good to excellent yield by Sm/TiCl4 mediated reductive cleavage of N=N bond in azo compounds and successive acylation in one pot. It offers an alternative method for the synthesis of amides from very simple starting materials directly.

  10. Electrophilic Pt(II) complexes: precision instruments for the initiation of transformations mediated by the cation-olefin reaction.

    Science.gov (United States)

    Felix, Ryan J; Munro-Leighton, Colleen; Gagné, Michel R

    2014-08-19

    A discontinuity exists between the importance of the cation-olefin reaction as the principal C-C bond forming reaction in terpene biosynthesis and the synthetic tools for mimicking this reaction under catalyst control; that is, having the product identity, stereochemistry, and functionality under the control of a catalyst. The main reason for this deficiency is that the cation-olefin reaction starts with a reactive intermediate (a carbocation) that reacts exothermically with an alkene to reform the reactive intermediate; not to mention that reactive intermediates can also react in nonproductive fashions. In this Account, we detail our efforts to realize catalyst control over this most fundamental of reactions and thereby access steroid like compounds. Our story is organized around our progress in each component of the cascade reaction: the metal controlled electrophilic initiation, the propagation and termination of the cyclization (the cyclase phase), and the turnover deplatinating events. Electrophilic Pt(II) complexes efficiently initiate the cation-olefin reaction by first coordinating to the alkene with selection rules that favor less substituted alkenes over more substituted alkenes. In complex substrates with multiple alkenes, this preference ensures that the least substituted alkene is always the better ligand for the Pt(II) initiator, and consequently the site at which all electrophilic chemistry is initiated. This control element is invariant. With a suitably electron deficient ligand set, the catalyst then activates the coordinated alkene to intramolecular addition by a second alkene, which initiates the cation-olefin reaction cascade and generates an organometallic Pt(II)-alkyl. Deplatination by a range of mechanisms (β-H elimination, single electron oxidation, two-electron oxidation, etc.) provides an additional level of control that ultimately enables A-ring functionalizations that are orthogonal to the cyclase cascade. We particularly focus on

  11. A case study of the mechanism of alcohol-mediated Morita Baylis-Hillman reactions. The importance of experimental observations.

    Science.gov (United States)

    Plata, R Erik; Singleton, Daniel A

    2015-03-25

    The mechanism of the Morita Baylis-Hillman reaction has been heavily studied in the literature, and a long series of computational studies have defined complete theoretical energy profiles in these reactions. We employ here a combination of mechanistic probes, including the observation of intermediates, the independent generation and partitioning of intermediates, thermodynamic and kinetic measurements on the main reaction and side reactions, isotopic incorporation from solvent, and kinetic isotope effects, to define the mechanism and an experimental mechanistic free-energy profile for a prototypical Morita Baylis-Hillman reaction in methanol. The results are then used to critically evaluate the ability of computations to predict the mechanism. The most notable prediction of the many computational studies, that of a proton-shuttle pathway, is refuted in favor of a simple but computationally intractable acid-base mechanism. Computational predictions vary vastly, and it is not clear that any significant accurate information that was not already apparent from experiment could have been garnered from computations. With care, entropy calculations are only a minor contributor to the larger computational error, while literature entropy-correction processes lead to absurd free-energy predictions. The computations aid in interpreting observations but fail utterly as a replacement for experiment.

  12. Computational tools for mechanistic discrimination in the reductive and metathesis coupling reactions mediated by titanium(IV) isopropoxide

    Indian Academy of Sciences (India)

    Akshai Kumar; Ashoka G Samuelson

    2012-11-01

    A theoretical study has been carried out at the B3LYP/LANL2DZ level to compare the reactivity of phenyl isocyanate and phenyl isothiocyanate towards titanium(IV) alkoxides. Isocyanates are shown to favour both mono insertion and double insertion reactions. Double insertion in a head-to-tail fashion is shown to be more exothermic than double insertion in a head-to-head fashion. The head-to-head double insertion leads to the metathesis product, a carbodiimide, after the extrusion of carbon dioxide. In the case of phenyl isothiocyanate, calculations favour the formation of only mono insertion products. Formation of a double insertion product is highly unfavourable. Further, these studies indicate that the reverse reaction involving the metathesis of N,N'-diphenyl carbodiimide with carbon dioxide is likely to proceed more efficiently than the metathesis reaction with carbon disulphide. This is in excellent agreement with experimental results as metathesis with carbon disulphide fails to occur. In a second study, multilayer MM/QM calculations are carried out on intermediates generated from reduction of titanium(IV) alkoxides to investigate the effect of alkoxy bridging on the reactivity of multinuclear Ti species. Bimolecular coupling of imines initiated by Ti(III) species leads to a mixture of diastereomers and not diastereoselective coupling of the imine. However if the reaction is carried out by a trimeric biradical species, diastereoselective coupling of the imine is predicted. The presence of alkoxy bridges greatly favours the formation of the d,l (±) isomer, whereas the intermediate without alkoxy bridges favours the more stable meso isomer. As a bridged trimeric species, stabilized by bridging alkoxy groups, correctly explains the diastereoselective reaction, it is the most likely intermediate in the reaction.

  13. Computational Analysis of AMPK-Mediated Neuroprotection Suggests Acute Excitotoxic Bioenergetics and Glucose Dynamics Are Regulated by a Minimal Set of Critical Reactions.

    Directory of Open Access Journals (Sweden)

    Niamh M C Connolly

    Full Text Available Loss of ionic homeostasis during excitotoxic stress depletes ATP levels and activates the AMP-activated protein kinase (AMPK, re-establishing energy production by increased expression of glucose transporters on the plasma membrane. Here, we develop a computational model to test whether this AMPK-mediated glucose import can rapidly restore ATP levels following a transient excitotoxic insult. We demonstrate that a highly compact model, comprising a minimal set of critical reactions, can closely resemble the rapid dynamics and cell-to-cell heterogeneity of ATP levels and AMPK activity, as confirmed by single-cell fluorescence microscopy in rat primary cerebellar neurons exposed to glutamate excitotoxicity. The model further correctly predicted an excitotoxicity-induced elevation of intracellular glucose, and well resembled the delayed recovery and cell-to-cell heterogeneity of experimentally measured glucose dynamics. The model also predicted necrotic bioenergetic collapse and altered calcium dynamics following more severe excitotoxic insults. In conclusion, our data suggest that a minimal set of critical reactions may determine the acute bioenergetic response to transient excitotoxicity and that an AMPK-mediated increase in intracellular glucose may be sufficient to rapidly recover ATP levels following an excitotoxic insult.

  14. An iridium-mediated C-H activation/CO2-carboxylation reaction of 1,1-bisdiphenylphosphinomethane.

    Science.gov (United States)

    Langer, Jens; Fabra, María José; García-Orduña, Pilar; Lahoz, Fernando J; Görls, Helmar; Oro, Luis A; Westerhausen, Matthias

    2010-09-07

    The reaction of 1,1-bisdiphenylphosphinomethane (dppm, 4 eq.) with [IrCl(coe)(2)](2) results in a solvent dependent equilibrium from which the complexes [IrCl(dppm)(dppm-H)(H)] (1) and [Ir(dppm)(2)]Cl (2) were isolated. When 2 is dissolved in methanol, [IrCl(dppm)(2)(H)][OCH(3)] (4) is formed as dominant species in solution. The C-H activation reaction which leads to 1 and 4 can be suppressed by adding an additional dppm ligand per iridium center resulting in the formation of [Ir(dppm)(3)]Cl (5). If the reaction of dppm with [IrX(coe)(2)](2) (X = Cl, I) is performed under an atmosphere of CO(2) the complexes [IrX(dppm)(H){(Ph(2)P)(2)C-COOH}] (6: X = Cl; 7: X = I) are formed by a CH activation/CO(2) carboxylation sequence. The reaction of 6 with NH(4)PF yields [IrCl(dppm)(2)(H)]PF(6).(10). Additionally the lithium compounds [Li(dme)(2)(dppm-H)] (3) and [Li(dme){(Ph(2)P)(2)CHCOO}](2) (8) were prepared for comparison. The molecular structures of the compounds 1, 3, 5, 7, 8 and of the related iridium complex [IrCl(dppm)(2)(H)]I (11) are reported.

  15. Pyrovanadolysis, a Pyrophosphorolysis-like Reaction Mediated by Pyrovanadate, Mn2+, and DNA Polymerase of Bacteriophage T7

    NARCIS (Netherlands)

    Akabayov, Barak; Kulczyk, Arkadiusz W.; Akabayov, Sabine R.; Theile, Christopher; McLaughlin, Larry W.; Beauchamp, Benjamin; van Oijen, Antoine M.; Richardson, Charles C.

    2011-01-01

    DNA polymerases catalyze the 3'-5'-pyrophosphorolysis of a DNA primer annealed to a DNA template in the presence of pyrophosphate (PPi). In this reversal of the polymerization reaction, deoxynucleotides in DNA are converted to deoxynucleoside 5'-triphosphates. Based on the charge, size, and geometry

  16. Cell-mediated immunity to histocompatibility antigens : controlling factors, with emphasis on Graft-versus-host reactions in mice

    NARCIS (Netherlands)

    H. Bril (Herman)

    1984-01-01

    textabstractGraft-versus-Host (GvH) disease is characterized by weight loss, diarrhea, skin lesions, hypofunction of the immune system with concomitant infections, etc. This syndrome is potentially lethal. GvH reactions, which underly this disease, may occur when immunocompetent T lymphocytes are tr

  17. 2-Hydroxy-3-methoxybenzoic acid attenuates mast cell-mediated allergic reaction in mice via modulation of the FcεRI signaling pathway.

    Science.gov (United States)

    Kim, Yeon-Yong; Je, In-Gyu; Kim, Min Jong; Kang, Byeong-Cheol; Choi, Young-Ae; Baek, Moon-Chang; Lee, Byungheon; Choi, Jin Kyeong; Park, Hae Ran; Shin, Tae-Yong; Lee, Soyoung; Yoon, Seung-Bin; Lee, Sang-Rae; Khang, Dongwoo; Kim, Sang-Hyun

    2017-01-01

    Mast cells are important effector cells in immunoglobulin (Ig) E-mediated allergic reactions such as asthma, atopic dermatitis and rhinitis. Vanillic acid, a natural product, has shown anti-oxidant and anti-inflammatory activities. In the present study, we investigated the anti-allergic inflammatory effects of ortho-vanillic acid (2-hydroxy-3-methoxybenzoic acid, o-VA) that was a derivative of vanillic acid isolated from Amomum xanthioides. In mouse anaphylaxis models, oral administration of o-VA (2, 10, 50 mg/kg) dose-dependently attenuated ovalbumin-induced active systemic anaphylaxis and IgE-mediated cutaneous allergic reactions such as hypothermia, histamine release, IgE production and vasodilation; administration of o-VA also suppressed the mast cell degranulator compound 48/80-induced anaphylaxis. In cultured mast cell line RBL-2H3 and isolated rat peritoneal mast cells in vitro, pretreatment with o-VA (1-100 μmol/L) dose-dependently inhibited DNP-HSA-induced degranulation of mast cells by decreasing the intracellular free calcium level, and suppressed the expression of pro-inflammatory cytokines TNF-α and IL-4. Pretreatment of RBL-2H3 cells with o-VA suppressed DNP-HSA-induced phosphorylation of Lyn, Syk, Akt, and the nuclear translocation of nuclear factor-κB. In conclusion, o-VA suppresses the mast cell-mediated allergic inflammatory response by blocking the signaling pathways downstream of high affinity IgE receptor (FcεRI) on the surface of mast cells.

  18. Synthesis, Crystal Structure of Ruthenium 1,2-Naphthoquinone-1-oxime Complex and Its Mediated C-C Coupling Reactions of Terminal Alkynes

    Institute of Scientific and Technical Information of China (English)

    SUN, Ke; WONG, Wing-Tak; LIU, Xiao-Xia; ZHANG, Bao-Yan

    2003-01-01

    Substituted decarbonylation reaction of ruthenium 1,2-naphthoquinone-1-oxime (1-nqo) complex, cis-, cis-[Ru{ η2-N(O)C10-H6O}2(CO)2] (1), with acetonitrile gave cis-, cis-[Ru { η2-N(O)C10H6O}2(CO)(NCMe)] (2). Complex 2 was fully characterized by 1H NMR, FAB MS, IR spectra and single crystal X-ray analysis. Complex 2 maintains the coordination structure of 1 with the two naphthoquinonic oxygen atoms, as well as the two oximato nitrogen atoms located cis to each other, showing that there is no ligand rearrangement of the 1-nqo ligands during the substitution reaction. The carbonyl group originally trans to the naphthoquinonic oxygen in one 1-nqo ligand is left in its original position [O(5)-Ru-C(1), 174.0(6)°], while the other one originally trans to the oximato group of the other 1-nqo llgand is substituted by NCMe [N(1)-Ru-N(3), 170.6(6)°].This shows that the carbonyl trans to oximato group is more labile than the one trans to naphthoquinonic O atom towards substitution. This is probably due to the comparatively stronger π back bonding from ruthenium metal to the carbonyl group trans to naphthoquinonic O atom, than the one trans to oximato group, resulting in the comparatively weaker Ru-CO bond for the latter and consequently easier replacement of this carbonyl. Selected coupling of phenylacetylene mediated by 2 gave a single trans-dimerization product 3, while 2 mediated coupling reaction of methyl propiolate produced three products:one trans-dimerization product 4 and two cyclotrimeric products 5 and 6.

  19. 1,6-asymmetric induction in boron-mediated aldol reactions: application to a practical total synthesis of (+)-discodermolide.

    Science.gov (United States)

    Paterson, Ian; Delgado, Oscar; Florence, Gordon J; Lyothier, Isabelle; Scott, Jeremy P; Sereinig, Natascha

    2003-01-01

    By relying solely on substrate-based stereocontrol, a practical total synthesis of the microtubule-stabilizing anticancer agent (+)-discodermolide has been realized. This exploits a novel aldol bond construction with 1,6-stereoinduction from the boron enolate of (Z)-enone 3 in addition to aldehyde 2. The 1,3-diol 7 is employed as a common building block for the C(1)-C(5), C(9)-C(16), and C(17)-C(24) subunits. [reaction--see text

  20. Influence of the solvent on the ground- and excited-state buffer-mediated proton-transfer reactions of a xanthenic dye.

    Science.gov (United States)

    Paredes, Jose M; Crovetto, Luis; Orte, Angel; Alvarez-Pez, Jose M; Talavera, Eva M

    2011-01-28

    The buffer-mediated proton-transfer reactions of the fluorescent xanthenic derivative 9-[1-(2-Methyl-4-methoxyphenyl)]-6-hydroxy-3H-xanthen-3-one (TG-II) have been studied in different aqueous media. We have employed various buffers to investigate the influence of donor/acceptor systems with different anion and/or cation chemical constituents on the kinetic parameters of proton-transfer. The kinetic parameters were recovered both in the ground-state by means of Fluorescence Lifetime Correlation Spectroscopy (FLCS) and in the excited-state by means of Time Correlated Single Photon Counting (TCSPC) and Global Compartmental Analysis (GCA). Both ground- and excited- deprotonation and protonation recovered rate constants in the presence of either phosphate or acetate buffer as donor/acceptor systems were similar. The presence of Tris-HCl buffer does not promote the excited-state proton-transfer (ESPT) reaction. The results indicate the influence of the ions on the ground-state proton-transfer (GSPT) rates and concomitantly on the ESPT reaction. The proton-transfer rate constants recovered here show a trend correlated with the Hofmeister series or the Marcus classification of ions.

  1. Highly selective and sensitive detection of miRNA based on toehold-mediated strand displacement reaction and DNA tetrahedron substrate.

    Science.gov (United States)

    Li, Wei; Jiang, Wei; Ding, Yongshun; Wang, Lei

    2015-09-15

    MicroRNAs (miRNAs) play important roles in a variety of biological processes and have been regarded as tumor biomarkers in cancer diagnosis and prognosis. In this work, a single-molecule counting method for miRNA analysis was proposed based on toehold-mediated strand displacement reaction (SDR) and DNA tetrahedron substrate. Firstly, a specially designed DNA tetrahedron was assembled with a hairpin at one of the vertex, which has an overhanging toehold domain. Then, the DNA tetrahedron was immobilized on the epoxy-functional glass slide by epoxy-amine reaction, forming a DNA tetrahedron substrate. Next, the target miRNA perhybridized with the toehold domain and initiated a strand displacement reaction along with the unfolding of the hairpin, realizing the selective recognization of miRNA. Finally, a biotin labeled detection DNA was hybridized with the new emerging single strand and the streptavidin coated QDs were used as fluorescent probes. Fluorescent images were acquired via epi-fluorescence microscopy, the numbers of fluorescence dots were counted one by one for quantification. The detection limit is 5 fM, which displayed an excellent sensitivity. Moreover, the proposed method which can accurately be identified the target miRNA among its family members, demonstrated an admirable selectivity. Furthermore, miRNA analysis in total RNA samples from human lung tissues was performed, suggesting the feasibility of this method for quantitative detection of miRNA in biomedical research and early clinical diagnostics.

  2. Developing single-molecule TPM experiments for direct observation of successful RecA-mediated strand exchange reaction.

    Science.gov (United States)

    Fan, Hsiu-Fang; Cox, Michael M; Li, Hung-Wen

    2011-01-01

    RecA recombinases play a central role in homologous recombination. Once assembled on single-stranded (ss) DNA, RecA nucleoprotein filaments mediate the pairing of homologous DNA sequences and strand exchange processes. We have designed two experiments based on tethered particle motion (TPM) to investigate the fates of the invading and the outgoing strands during E. coli RecA-mediated pairing and strand exchange at the single-molecule level in the absence of force. TPM experiments measure the tethered bead Brownian motion indicative of the DNA tether length change resulting from RecA binding and dissociation. Experiments with beads labeled on either the invading strand or the outgoing strand showed that DNA pairing and strand exchange occurs successfully in the presence of either ATP or its non-hydrolyzable analog, ATPγS. The strand exchange rates and efficiencies are similar under both ATP and ATPγS conditions. In addition, the Brownian motion time-courses suggest that the strand exchange process progresses uni-directionally in the 5'-to-3' fashion, using a synapse segment with a wide and continuous size distribution.

  3. [Allergic reactions to transfusion].

    Science.gov (United States)

    Hergon, E; Paitre, M L; Coeffic, B; Piard, N; Bidet, J M

    1987-04-01

    Frequent allergic reactions following transfusion are observed. Usually, they are benign but sometimes we observe severe allergic reactions. Adverse reactions may be brought about by least two mechanisms. First, immediate-type hypersensibility reactions due to IgE. Secondly, anaphylactic-type reactions due to interaction between transfused IgA and class specific anti IgA in the recipient's plasma. They are characterized by their severest form (anaphylactic shock). The frequency of severe reactions following the transfusion blood plasma is very low. These transfusion reactions are complement-mediated and kinins-mediated. Prevention of allergic reactions is necessary among blood donors and recipients.

  4. Presence and function of dopamine transporter (DAT in stallion sperm: dopamine modulates sperm motility and acrosomal integrity.

    Directory of Open Access Journals (Sweden)

    Javier A Urra

    Full Text Available Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT, serotonin (SERT and norepinephrine (NET transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylaminostyryl]-N-methylpyridinium iodide (ASP(+, as substrate. In addition, we also showed that dopamine (1 mM treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909 and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility.

  5. A Practical Modeling Approach for NAPL Dissolution Kinetics, Microbially-Mediated Redox Reactions and Aquifer-Aquitard Diffusion to Assess Remedial Options

    Science.gov (United States)

    Parker, J.; Kim, U.; Widdowson, M.; Chappel, F.

    2008-12-01

    Explicit modeling of contaminant dissolution from heterogeneously distributed NAPL sources, microbial growth and reaction kinetics, and diffusion into or out of low permeability layers pose significant difficulties. These include the need to estimate a large number of parameters, which may subject to great uncertainty due to inverse problem ill-posedness given limited data, and to a lesser extent, the large computational effort that may be required to solve a rigorously formulated problem. An upscaled model for NAPL dissolution kinetics is utilized in the present study based on previous work, with extentions to consider concurrent effects of residual DNAPL and pools or lenses and to consider multi-component NAPL mixtures. An approach is presented to model microbially-mediated redox reactions subject to the assumption that microbial growth and reaction rates are primarily limited by transport processes rather than by microbial kinetics at time and space scales relevant for many remediation problems. The simplified model requires only stoichiometric coefficients for electron donor and electron acceptor half-reactions and the fraction of electron donor needed for cell synthesis. Contaminant diffusion into low permeability layers and subsequent back-diffusion is approximated as a first-order mass transfer problem with an effective mass transfer coefficient computed from aquifer-aquitard properties by equating second moments of diffusion and mass transfer solutions. Accuracy of the simplified model formulation is evaluated for a hypothetical problem involving a DNAPL source consisting of a mixture of TCE and Stoddard solvent with background dissolved organic carbon, oxygen and sulfate in groundwater for 40 years followed by injection of vegetable oil as a supplemental electron donor to enhance reductive dechlorination. The simplified solution is compared to numerical results that consider multi-species Monod kinetics with explicit treatment of back-diffusion.

  6. A smart hydrogel-based time bomb triggers drug release mediated by pH-jump reaction

    Directory of Open Access Journals (Sweden)

    Prapatsorn Techawanitchai, Naokazu Idota, Koichiro Uto, Mitsuhiro Ebara and Takao Aoyagi

    2012-01-01

    Full Text Available We demonstrate a timed explosive drug release from smart pH-responsive hydrogels by utilizing a phototriggered spatial pH-jump reaction. A photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (o-NBA was integrated into poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide (P(NIPAAm-co-CIPAAm hydrogels. o-NBA-hydrogels demonstrated the rapid release of protons upon UV irradiation, allowing the pH inside the gel to decrease to below the pKa value of P(NIPAAm-co-CIPAAm. The generated protons diffused gradually toward the non-illuminated area, and the diffusion kinetics could be controlled by adjusting the UV irradiation time and intensity. After irradiation, we observed the enhanced release of entrapped L-3,4-dihydroxyphenylalanine (DOPA from the gels, which was driven by the dissociation of DOPA from CIPAAm. Local UV irradiation also triggered the release of DOPA from the non-illuminated area in the gel via the diffusion of protons. Conventional systems can activate only the illuminated region, and their response is discontinuous when the light is turned off. The ability of the proposed pH-jump system to permit gradual activation via proton diffusion may be beneficial for the design of predictive and programmable devices for drug delivery.

  7. Chimeric Antibody-Binding Vitreoscilla Hemoglobin (VHb Mediates Redox-Catalysis Reaction: New Insight into the Functional Role of VHb

    Directory of Open Access Journals (Sweden)

    Yaneenart Suwanwong, Malin Kvist, Chartchalerm Isarankura-Na-Ayudhya, Natta Tansila, Leif Bulow, Virapong Prachayasittikul

    2006-01-01

    Full Text Available Experimentation was initiated to explore insight into the redox-catalysis reaction derived from the heme prosthetic group of chimeric Vitreoscilla hemoglobin (VHb. Two chimeric genes encoding chimeric VHbs harboring one and two consecutive sequences of Fc-binding motif (Z-domain were successfully constructed and expressed in E. coli strain TG1. The chimeric ZVHb and ZZVHb were purified to a high purity of more than 95% using IgG-Sepharose affinity chromatography. From surface plasmon resonance, binding affinity constants of the chimeric ZVHb and ZZVHb to human IgG were 9.7 x 107 and 49.1 x 107 per molar, respectively. More importantly, the chimeric VHbs exhibited a peroxidase-like activity determined by activity staining on native PAGE and dot blotting. Effects of pH, salt, buffer system, level of peroxidase substrate and chromogen substrate were determined in order to maximize the catalytic reaction. From our findings, the chimeric VHbs displayed their maximum peroxidase-like activity at the neutral pH (~7.0 in the presence of high concentration (20-40 mM of hydrogen peroxide. Under such conditions, the detection limit derived from the calibration curve was at 250 ng for the chimeric VHbs, which was approximately 5-fold higher than that of the horseradish peroxidase. These findings reveal the novel functional role of Vitreoscilla hemoglobin indicating a high trend of feasibility for further biotechnological and medical applications.

  8. Role of cluster size and substrate in the gas phase CC bond coupling reactions of allyl halides mediated by Agn+ and Agn-1H+ cluster cations

    Science.gov (United States)

    Wang, Farrah Qiuyun; Khairallah, George N.; O'Hair, Richard A. J.

    2009-06-01

    Previous studies have demonstrated that the silver hydride cluster cation Ag4H+ promotes CC bond coupling of allylbromide [G.N. Khairallah, R.A.J. O'Hair, Angewandte Chemie International Edition 44 (2005) 728]. Here the influence of both the nature and the size of the silver cluster cation and the substrate on CC bond coupling are examined. Thus each of the cations Ag2H+, Ag4H+, Ag3+, and Ag5+ were allowed to react with three different halides: allyl chloride, allyl bromide and allyl iodide. No CC bond coupling is observed in the reactions of the cluster cations with allyl chloride. There are four main reaction sequences that result in CC bond coupling for allyl bromide and allyl iodide mediated by Agn+ and Agn-1H+ clusters: (i) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X: Agn+ --> Agn(C3H5X)+ --> AgnX2+. This only occurs in the cases of: n = 3 and X = I; n = 5 and X = Br. (ii) A sequence involving the reactions of silver cluster cations with two molecules of C3H5X via an organometallic intermediate: Agn+ --> Agn-1(C3H5)+ --> Agn-1X+. This only occurs in the cases of: n = 5 and X = Br and I. (iii) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X: Agn-1H+ --> Agn-1X+ --> Agn-1X(C3H5X)+ --> Ag(C3H5)2+ and Agn-1X3+. This only occurs in the cases of: n = 5 and X = Br and I. (iv) A sequence involving the reactions of silver hydride cluster cations with three molecules of C3H5X via an organometallic intermediate: Agn-1H+ --> Agn-1X+ --> Agn-3(C3H5)+ --> Ag(C3H5)2+ and Agn-3X+. This only occurs in the cases of: n = 5 and X = I.

  9. Giardia and Cryptosporidium spp. dissemination during wastewater treatment and comparative detection via immunofluorescence assay (IFA), nested polymerase chain reaction (nested PCR) and loop mediated isothermal amplification (LAMP).

    Science.gov (United States)

    Gallas-Lindemann, Carmen; Sotiriadou, Isaia; Plutzer, Judit; Noack, Michael J; Mahmoudi, Mohammad Reza; Karanis, Panagiotis

    2016-06-01

    Environmental water samples from the Lower Rhine area in Germany were investigated via immunofluorescence assays (IFAs), nested polymerase chain reaction (nested PCR) and loop-mediated isothermal amplification (LAMP) to detect the presence of Giardia spp. (n=185) and Cryptosporidium spp. (n=227). The samples were concentrated through filtration or flocculation, and oocysts were purified via centrifugation through a sucrose density gradient. For all samples, IFA was performed first, followed by DNA extraction for the nested PCR and LAMP assays. Giardia cysts were detected in 105 samples (56.8%) by IFA, 62 samples (33.5%) by nested PCR and 79 samples (42.7%) by LAMP. Cryptosporidium spp. were detected in 69 samples (30.4%) by IFA, 95 samples (41.9%) by nested PCR and 99 samples (43.6%) by LAMP. According to these results, the three detection methods are complementary for monitoring Giardia and Cryptosporidium in environmental waters.

  10. Loop mediated isothermal amplification assay using hydroxy naphthol blue, conventional polymerase chain reaction and real-time PCR in the diagnosis of intraocular tuberculosis.

    Science.gov (United States)

    Balne, P K; Basu, S; Rath, S; Barik, M R; Sharma, S

    2015-01-01

    This study is a comparative evaluation (Chi-square test) of a closed tube loop mediated isothermal amplification assay using hydroxy naphthol blue dye (HNB-LAMP), real-time polymerase chain reaction (PCR) and conventional PCR in the diagnosis of intraocular tuberculosis. Considering clinical presentation as the gold standard in 33 patients, the sensitivity of HNB-LAMP assay (75.8%) was higher (not significant, P value 0.2) than conventional PCR (57.6%) and lower than real-time PCR (90.9%). Specificity was 100% by all three methods. No amplification was observed in negative controls (n = 20) by all three methods. The cost of the HNB-LAMP assay was Rs. 500.00 and it does not require thermocycler, therefore, it can be used as an alternative to conventional PCR in resource-poor settings.

  11. Loop mediated isothermal amplification assay using hydroxy naphthol blue, conventional polymerase chain reaction and real-time PCR in the diagnosis of intraocular tuberculosis

    Directory of Open Access Journals (Sweden)

    P K Balne

    2015-01-01

    Full Text Available This study is a comparative evaluation (Chi-square test of a closed tube loop mediated isothermal amplification assay using hydroxy naphthol blue dye (HNB-LAMP, real-time polymerase chain reaction (PCR and conventional PCR in the diagnosis of intraocular tuberculosis. Considering clinical presentation as the gold standard in 33 patients, the sensitivity of HNB-LAMP assay (75.8% was higher (not significant, P value 0.2 than conventional PCR (57.6% and lower than real-time PCR (90.9%. Specificity was 100% by all three methods. No amplification was observed in negative controls (n = 20 by all three methods. The cost of the HNB-LAMP assay was Rs. 500.00 and it does not require thermocycler, therefore, it can be used as an alternative to conventional PCR in resource-poor settings.

  12. Oxidative Cyclization of Sulfamate Esters Using NaOCl - A Metal-Mediated Hoffman-Löffler Freytag Reaction.

    Science.gov (United States)

    Zalatan, David N; Du Bois, J

    2009-01-01

    Intramolecular C-H amination with sulfamate esters occurs under the action of dinuclear Rh catalysts and iodine(III) oxidants, and has recently emerged as a powerful tool for synthesis. Insights gained through mechanistic studies of this process suggest that other terminal oxidants, including common halogenating agents such as NaOCl, could function to promote the cyclization reaction. Results described in this report demonstrate that the combination of NaOCl and 3 mol% Rh(2)(oct)(4) is effective in select cases for converting sulfamate substrates to the corresponding [1,2,3]-oxathiazinane-2,2-dioxide heterocycles. The mechanism for C-H functionalization, however, is distinct from that induced by hypervalent iodine reagents and likely involves the intermediacy of an N-centered radical.

  13. Oxidative Cyclization of Sulfamate Esters Using NaOCl – A Metal-Mediated Hoffman-Löffler Freytag Reaction

    Science.gov (United States)

    Zalatan, David N.; Du Bois, J.

    2009-01-01

    Intramolecular C–H amination with sulfamate esters occurs under the action of dinuclear Rh catalysts and iodine(III) oxidants, and has recently emerged as a powerful tool for synthesis. Insights gained through mechanistic studies of this process suggest that other terminal oxidants, including common halogenating agents such as NaOCl, could function to promote the cyclization reaction. Results described in this report demonstrate that the combination of NaOCl and 3 mol% Rh2(oct)4 is effective in select cases for converting sulfamate substrates to the corresponding [1,2,3]-oxathiazinane-2,2-dioxide heterocycles. The mechanism for C–H functionalization, however, is distinct from that induced by hypervalent iodine reagents and likely involves the intermediacy of an N-centered radical. PMID:19319207

  14. The mediation reaction between the external couple Ferri/Ferrocyanide and Os(II) bipyridile poly-vinylpyridile films coated onto glassy carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ybarra, Gabriel; Moina, Carlos [Centro de Investigacion sobre Electrodeposicion y Procesos Superficiales, Instituto Nacional de Tecnologia Industrial, CC 157, 1650 San Martin (Argentina); Florit, M. Ines [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, 1900 La Plata (Argentina); Posadas, Dionisio [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, 1900 La Plata (Argentina)], E-mail: dposadas@inifta.unlp.edu.ar

    2008-05-30

    The oxidation-reduction of the Ferri/Ferrocyanide couple in solution onto modified glassy carbon Rotating Disk Electrodes (RDE) covered by Os(II) bipyridile poly-vinylpyridile (OsBPP) polymer was studied at room temperature. Steady state polarization curves were carried out as a function of the rotation speed, the polymer thickness and the concentration of redox centers within the polymer. This system has the characteristic that the formal redox potentials of both the external redox couple (E{sup 0}'(Fe(CN){sub 6}{sup 3-/4-}) = + 0.225 V vs. SCE) and the mediator polymer (E{sup 0}'(OsBPP) = 0.260 V vs. SCE) lie very close. It is demonstrated that diffusion of the Ferri/Ferrocyanide inside the polymer can be ruled out. Since the processes of charge transfer at the metal/polymer and the mediating reaction are fast, the experimental results can be interpreted in terms of a kinetics in which the charge transport in the polymer or the diffusion in the solution may be the rate determining step, according to the experimental conditions. A simple model is considered that allows interpreting the experimental results quantitatively. Application of this model allows the determination of the diffusion coefficient of the electrons within the film, D{sub e} {approx} 10{sup -10} cm{sup 2} s{sup -1}.

  15. The effect of salmeterol and salbutamol on mediator release and skin responses in immediate and late phase allergic cutaneous reactions

    DEFF Research Database (Denmark)

    Petersen, Lars Jelstrup; Skov, P S

    1999-01-01

    BACKGROUND: Salmeterol is a long-acting beta2-agonist which in animal studies has been shown to possess anti-inflammatory effects on early (EAR) and late (LPR) phase allergic responses. PURPOSE: To evaluate the anti-inflammatory effects of intradermally injected salmeterol and salbutamol on clini......BACKGROUND: Salmeterol is a long-acting beta2-agonist which in animal studies has been shown to possess anti-inflammatory effects on early (EAR) and late (LPR) phase allergic responses. PURPOSE: To evaluate the anti-inflammatory effects of intradermally injected salmeterol and salbutamol...... and histamine were not or only marginally reduced. Salmeterol and salbutamol (10(-6) M) inhibited clinical LPR at 6 h by 71% and 48%, Except for the clinical LPR, no statistical differences were found between the two drugs on any parameters. None of the drugs inhibited levels of histamine, tryptase......, myeloperoxidase, or eosinophil cationic protein in LPR. CONCLUSIONS: Salmeterol and salbutamol inhibited allergen-induced skin responses, and reduced mediator release in EAR but not LPR. In general, the anti-inflammatory effects of salmeterol did not differ from those induced by salbutamol....

  16. The Influence of Receptor-Mediated Interactions on Reaction-Diffusion Mechanisms of Cellular Self-organisation

    KAUST Repository

    Klika, Václav

    2011-11-10

    Understanding the mechanisms governing and regulating self-organisation in the developing embryo is a key challenge that has puzzled and fascinated scientists for decades. Since its conception in 1952 the Turing model has been a paradigm for pattern formation, motivating numerous theoretical and experimental studies, though its verification at the molecular level in biological systems has remained elusive. In this work, we consider the influence of receptor-mediated dynamics within the framework of Turing models, showing how non-diffusing species impact the conditions for the emergence of self-organisation. We illustrate our results within the framework of hair follicle pre-patterning, showing how receptor interaction structures can be constrained by the requirement for patterning, without the need for detailed knowledge of the network dynamics. Finally, in the light of our results, we discuss the ability of such systems to pattern outside the classical limits of the Turing model, and the inherent dangers involved in model reduction. © 2011 Society for Mathematical Biology.

  17. The tert-butoxyl radical mediated hydrogen atom transfer reactions of the Parkinsonian proneurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and selected tertiary amines.

    Science.gov (United States)

    Suleman, N Kamrudin; Flores, Joey; Tanko, James M; Isin, Emre Mehmet; Castagnoli, Neal

    2008-09-15

    Previous studies have shown that the hydrogen atom transfer (HAT) reactions of tert-butoxyl radical from the Parkinsonian proneurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) occur with low selectivity at the allylic and non-allylic alpha-C-H positions. In this paper, we report a more comprehensive regiochemical study on the reactivity of the tert-butoxyl radical as well as on the associated primary kinetic deuterium isotope effects for the various hydrogen atom abstractions of MPTP. In addition, the results of a computational study to estimate the various C-H bond dissociation energies of MPTP are presented. The results of the present study show the allylic/non-allylic selectivity is approximately 73:21. The behavior of the tert-butoxyl radical mediated oxidation of MPTP contrasts with this reaction as catalyzed by monoamine oxidase B (MAO-B) that occurs selectively at the allylic alpha-carbon. These observations lead to the conclusion that the tert-butoxyl radical is not a good chemical model for the MAO-B-catalyzed bioactivation of MPTP.

  18. Fenton reaction-mediated fluorescence quenching of N-acetyl-L-cysteine-protected gold nanoclusters: analytical applications of hydrogen peroxide, glucose, and catalase detection.

    Science.gov (United States)

    Deng, Hao-Hua; Wu, Gang-Wei; He, Dong; Peng, Hua-Ping; Liu, Ai-Lin; Xia, Xing-Hua; Chen, Wei

    2015-11-21

    Given the importance of hydrogen peroxide (H2O2) in many biological processes and its wide application in various industries, the demand for sensitive, accurate, and economical H2O2 sensors is high. In this study, we used Fenton reaction-stimulated fluorescence quenching of N-acetyl-L-cysteine-protected gold nanoclusters (NAC-AuNCs) as a reporter system for the determination of H2O2. After the experimental conditions were optimized, the sensing platform enabled the analysis of H2O2 with a limit of detection (LOD) as low as 0.027 μM. As the glucose oxidase cascade leads to the generation of H2O2 and catalase catalyzes the decomposition of H2O2, these two biocatalytic procedures can be probed by the Fenton reaction-mediated quenching of NAC-AuNCs. The LOD for glucose was found to be 0.18 μM, and the linear range was 0.39-27.22 μM. The LOD for catalase was 0.002 U mL(-1), and the linear range was 0.01-0.3 U mL(-1). Moreover, the proposed sensing methods were successfully applied for human serum glucose detection and the non-invasive determination of catalase activity in human saliva, demonstrating their great potential for practical applications.

  19. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Galenda, A., E-mail: galenda@ieni.cnr.it [CNR-IENI, Istituto per l’Energetica e le Interfasi, Corso Stati Uniti, 4 35127 Padova (Italy); Crociani, L.; Habra, N. El; Favaro, M. [CNR-IENI, Istituto per l’Energetica e le Interfasi, Corso Stati Uniti, 4 35127 Padova (Italy); Natile, M.M. [CNR-IENI, Istituto per l’Energetica e le Interfasi, Dipartimento di Scienze Chimiche, Università di Padova, via F. Marzolo, 1 35131 Padova (Italy); Rossetto, G. [CNR-IENI, Istituto per l’Energetica e le Interfasi, Corso Stati Uniti, 4 35127 Padova (Italy)

    2014-09-30

    Highlights: • Boron and/or nitrogen-doped TiO{sub 2} for photocatalytic wastewater treatment. • Methyl red degradation/mineralisation as a function of pH, acids and dopants. • Adsorption time influence on photocatalytic process. • Recovery of worn-out catalyst. - Abstract: Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO{sub 2}-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV–vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.

  20. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO2

    Science.gov (United States)

    Galenda, A.; Crociani, L.; Habra, N. El; Favaro, M.; Natile, M. M.; Rossetto, G.

    2014-09-01

    Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV-vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.

  1. Integrity of the plasma membrane, the acrosomal membrane, and the mitochondrial membrane potential of sperm in Nelore bulls from puberty to sexual maturity

    Directory of Open Access Journals (Sweden)

    L.S.L.S. Reis

    2016-06-01

    Full Text Available ABSTRACT This study evaluated the plasma membrane integrity, acrosomal membrane integrity, and mitochondrial membrane potential of Nelore bull sperm from early puberty to early sexual maturity and their associations with sperm motility and vigor, the mass motility of the spermatozoa (wave motion, scrotal circumference, and testosterone. Sixty Nelore bulls aged 18 to 19 months were divided into four lots (n=15 bulls/lot and evaluated over 280 days. Semen samples, collected every 56 days by electroejaculation, were evaluated soon after collection for motility, vigor and wave motion under an optical microscope. Sperm membrane integrity, acrosomal integrity, and mitochondrial activity were evaluated under a fluorescent microscope using probe association (FITC-PSA, PI, JC-1, H342. The sperm were classified into eight integrity categories depending on whether they exhibited intact or damaged membranes, an intact or damaged acrosomal membrane, and high or low mitochondrial potential. The results show that bulls have a low amount of sperm with intact membranes at puberty, and the sperm show low motility, vigor, and wave motion; however, in bulls at early sexual maturity, the integrity of the sperm membrane increased significantly. The rate of sperm membrane damage was negatively correlated with motility, vigor, wave motion, and testosterone in the bulls, and a positive correlation existed between sperm plasma membrane integrity and scrotal circumference. The integrity of the acrosomal membrane was not influenced by puberty. During puberty and into early sexual maturity, bulls show low sperm mitochondrial potential, but when bulls reached sexual maturity, high membrane integrity with high mitochondrial potential was evident.

  2. In vitro effects of nonylphenol on motility, mitochondrial, acrosomal and chromatin integrity of ram and boar spermatozoa.

    Science.gov (United States)

    Uguz, C; Varisli, O; Agca, C; Evans, T; Agca, Y

    2015-10-01

    The objective of this study was to determine the effects of nonylphenol (NP) on viability of ram and boar sperm in vitro. Ram or boar spermatozoa were exposed to 1, 10, 100, 250 and 500 μg NP ml(-1) for 1, 2, 3 or 4 h. Computer-assisted sperm motility analysis (CASA) system was used to evaluate sperm motility characteristics. Flow cytometry was used to determine mitochondrial membrane potential (MMP) and chromatin integrity, while epifluorescent microscopy was used to determine sperm acrosomal status. Exposure of both species spermatozoa to 250 and 500 μg NP ml(-1) was detrimental to progressive motility (P boar spermatozoa with high MMP declined drastically after exposures to ≥250 μg ml(-1) NP (P boar spermatozoa and 10 μg ml(-1) NP for ram spermatozoa. These data show adverse effects of NP on ram and boar spermatozoa and thus its potential harmful effects on male reproduction as NP is found in fruits, vegetables, human milk, fish and livestock products.

  3. IDENTIFICATION OF ACROSOME AS THE MAIN ANTIGEN OF THE SPERM CELLS PROVOKING AUTOANTIBODIES IN VASECTOMIZED IRANIAN MEN

    Directory of Open Access Journals (Sweden)

    M R Nowroozi

    2008-12-01

    Full Text Available "nVasectomy is one of the extensively used methods of contraception in family planning programs. Antisperm antibodies (ASA develop after vasectomy which can result in auto-immune male infertility. The precise sperm antigens involved in the autoimmune response are still poorly defined, therefore we determined the circulating ASA and identified relevant sperm antigens based on localization of binding sites of ASA to sperm cell antigens, using a rapid, inexpensive and clinically relevant assay in vasectomized men. Results showed that 2.5% of men had ASA at the time of vasectomy, whereas 53.5% of the study population subsequently developed ASA. The numbers of men with circulating ASA increased significantly for the first three months after vasectomy. These antibodies were distinguishable into three groups based on their bindings to different sites of sperm cell antigens including against acrosome and tail in 67.56% and 10.8%, respectively; 21.6% of subjects had antibody to the other parts of the sperm cell antigens. The results of this study are discussed in terms of an autoimmune response against sperm antigens and development of ASA.

  4. Identification of region-specific yeast artificial chromosomes using pools of Alu element-mediated polymerase chain reaction probes labeled via linear amplification

    Energy Technology Data Exchange (ETDEWEB)

    Cole, C.G.; Bobrow, M.; Bentley, D.R.; Dunham, I. (United Medical and Dental Schools of Guy' s and St. Thomas Hospitals, London Bridge, London, England (United Kingdom)); Patel, K.; Shipley, J.; Sheer, D. (Imperial Cancer Research Fund, London (United Kingdom))

    1992-12-01

    The ability to identify large numbers of yeast artificial chromosomes (YACS) specific to any given genomic region rapidly and efficiently enhances both the construction of clone maps and the isolation of region-specific landmarks (e.g., polymorphic markers). The authors describe a method of preparing region-specific single-stranded hybridization probes from Alu element-mediated polymerase chain reaction (Alu-PCR) products of somatic cell hybrids for YAC library screening. Pools of up to 50 cloned Alu-PCR products from an irradiation-reduced hybrid containing 22q11.2-q13.1 were labeled to high specific activity by linear amplification using a single vector primer. The resulting single-stranded probes were extensively competed to remove repetitive sequences, while retaining the full complexity of the probe. Extensive coverage of the region by YACs using multiple probe pools was demonstrated as many YACs were detected more than once. In situ analysis using chosen YACs confirmed that the clones were specific for the region. Thus, this pooled probe approach constitutes a rapid method to identify large numbers of YACs relevant to a large chromosomal region. 29 refs., 4 figs.

  5. Identification of region-specific yeast artificial chromosomes using pools of Alu element-mediated polymerase chain reaction probes labeled via linear amplification.

    Science.gov (United States)

    Cole, C G; Patel, K; Shipley, J; Sheer, D; Bobrow, M; Bentley, D R; Dunham, I

    1992-12-01

    The ability to identify large numbers of yeast artificial chromosomes (YACs) specific to any given genomic region rapidly and efficiently enhances both the construction of clone maps and the isolation of region-specific landmarks (e.g., polymorphic markers). We describe a method of preparing region-specific single-stranded hybridization probes from Alu element-mediated polymerase chain reaction (Alu-PCR) products of somatic cell hybrids for YAC library screening. Pools of up to 50 cloned Alu-PCR products from an irradiation-reduced hybrid containing 22q11.2-q13.1 were labeled to high specific activity by linear amplification using a single vector primer. The resulting single-stranded probes were extensively competed to remove repetitive sequences, while retaining the full complexity of the probe. Extensive coverage of the region by YACs using multiple probe pools was demonstrated as many YACs were detected more than once. In situ analysis using chosen YACs confirmed that the clones were specific for the region. Thus, this pooled probe approach constitutes a rapid method to identify large numbers of YACs relevant to a large chromosomal region.

  6. Humoral and Cell-mediated Autoimmune Reactions to Human Acidic Ribosomal P2 Protein in Individuals Sensitized to Aspergillus fumigatus P2 Protein

    Science.gov (United States)

    Mayer, Christina; Appenzeller, Ulrich; Seelbach, Heike; Achatz, Gernot; Oberkofler, Hannes; Breitenbach, Michael; Blaser, Kurt; Crameri, Reto

    1999-01-01

    A panel of cDNAs encoding allergenic proteins was isolated from an Aspergillus fumigatus cDNA library displayed on the surface of filamentous phage. Solid phase–immobilized serum immunoglobulin E (IgE) from A. fumigatus–allergic individuals was used to enrich phage displaying IgE-binding molecules. One of the cDNAs encoded a 11.1-kD protein that was identified as acidic ribosomal phosphoprotein type 2 (P2 protein). The allergen, formally termed rAsp f 8, shares >62% sequence identity and >84% sequence homology to corresponding eukaryotic P2 proteins, including human P2 protein. The sequences encoding human and fungal P2 protein were subcloned, expressed in Escherichia coli as His6-tagged fusion proteins, and purified by Ni2+–chelate affinity chromatography. Both recombinant P2 proteins were recognized by IgE antibodies from allergic individuals sensitized to the A. fumigatus P2 protein and elicited strong type 1–specific skin reactions in these individuals. Moreover, human and fungal P2 proteins induced proliferative responses in peripheral blood mononuclear cells of A. fumigatus– allergic subjects sensitized to the fungal P2 protein. These data provide strong evidence for in vitro and in vivo humoral and cell-mediated autoreactivity to human P2 protein in patients suffering from chronic A. fumigatus allergy. PMID:10224291

  7. Quantification and evaluation of kinetic bio-catalytic pathway of horseradish peroxidase in an electron mediated reaction system and its applications in plant extracts.

    Science.gov (United States)

    Krishna, Honnur; Nagaraja, Padmarajaiah; Shivakumar, Anantharaman; Chamaraja, Nelligere A; Aradhana, Narayan

    2013-02-01

    The intermolecular coupling of 2,5-dimethoxyaniline (DMA) as mediated electron transfer reaction in presence of H(2)O(2) and peroxidase in acetate buffer of pH 4.2 resulting green colored product having maximum absorption at λ(max)=740 nm was investigated by spectrophotometer. Under optimum conditions, linearity range for the quantification of H(2)O(2) was 2.0-288.0 μM and for peroxidase were 0.59-9.46 and 0.443-9.46 nM by kinetic and fixed-time method, respectively. The catalytic efficiency and catalytic power were K(eff)(D)=2.354 × 10(5)M(-1)min(-1) and K(pow)(D)=4.59 × 10(-4)min(-1), respectively. From the plot of d(1/D(o)) vs d(1/V(o)) and d(1/H(o)) vs d(1/V(o)), Michaelis-Menten constants for DMA and H(2)O(2)were found that K(m)(D)=1,458 μM and [Formula: see text] =301 μM. Applicability of the method was tested for peroxidase activity in some plant extracts and compared with guaiacol/peroxidase system. Regarding superiority of the method, it is suggested that DMA/peroxidase system can be a better hydrogen donor for HRP assay than guaiacol system as evident from kinetic data.

  8. Quantification and evaluation of kinetic bio-catalytic pathway of horseradish peroxidase in an electron mediated reaction system and its applications in plant extracts

    Science.gov (United States)

    Krishna, Honnur; Nagaraja, Padmarajaiah; Shivakumar, Anantharaman; Chamaraja, Nelligere A.; Aradhana, Narayan

    2013-02-01

    The intermolecular coupling of 2,5-dimethoxyaniline (DMA) as mediated electron transfer reaction in presence of H2O2 and peroxidase in acetate buffer of pH 4.2 resulting green colored product having maximum absorption at λmax = 740 nm was investigated by spectrophotometer. Under optimum conditions, linearity range for the quantification of H2O2 was 2.0-288.0 μM and for peroxidase were 0.59-9.46 and 0.443-9.46 nM by kinetic and fixed-time method, respectively. The catalytic efficiency and catalytic power were KeffD = 2.354 × 105 M-1 min-1 and KpowD = 4.59 × 10-4 min-1, respectively. From the plot of d(1/Do) vs d(1/Vo) and d(1/Ho) vs d(1/Vo), Michaelis-Menten constants for DMA and H2O2were found that KmD = 1458 μM and KmHO = 301 μM. Applicability of the method was tested for peroxidase activity in some plant extracts and compared with guaiacol/peroxidase system. Regarding superiority of the method, it is suggested that DMA/peroxidase system can be a better hydrogen donor for HRP assay than guaiacol system as evident from kinetic data.

  9. Binding of Sperm to the Zona Pellucida Mediated by Sperm Carbohydrate-Binding Proteins is not Species-Specific in Vitro between Pigs and Cattle

    Directory of Open Access Journals (Sweden)

    Minoru Nakano

    2013-01-01

    Full Text Available Carbohydrates are candidates for the basis of species-selective interaction of gametes during mammalian fertilization. In this study, we sought to clarify the roles of sugar residues in the species-selective, sperm–oocyte interaction in pigs and cattle. Acrosome-intact porcine and bovine sperm exhibited their strongest binding affinities for β-Gal and α-Man residues, respectively. Porcine-sperm specificity changed from β-Gal to α-Man after the acrosome reaction, while bovine-sperm specificity did not. Binding of acrosome-intact and acrosome-reacted sperm decreased after trypsinization, indicating that the carbohydrate-binding components are proteins. While immature oocytes bound homologous sperm preferentially to heterologous sperm, oocytes matured in vitro bound similar numbers of homologous and heterologous sperm. Lectin staining revealed the aggregation of α-Man residues on the outer surface of the porcine zona during maturation. In both species, zona-free, mature oocytes bound homologous sperm preferentially to heterologous sperm. The lectin-staining patterns of the zona pellucida and zona-free oocytes coincided with the carbohydrate-binding specificities of acrosome-intact and acrosome-reacted sperm, respectively, supporting the involvement of carbohydrates in gamete recognition in pigs and cattle. These results also indicate that sperm-zona pellucida and sperm–oolemma bindings are not strictly species-specific in pigs and cattle, and further suggest that sperm penetration into the zona and/or fusion with oolemma may be species-specific between pigs and cattle.

  10. Binding of Sperm to the Zona Pellucida Mediated by Sperm Carbohydrate-Binding Proteins is not Species-Specific in Vitro between Pigs and Cattle.

    Science.gov (United States)

    Takahashi, Kazuya; Kikuchi, Kazuhiro; Uchida, Yasuomi; Kanai-Kitayama, Saeko; Suzuki, Reiichiro; Sato, Reiko; Toma, Kazunori; Geshi, Masaya; Akagi, Satoshi; Nakano, Minoru; Yonezawa, Naoto

    2013-01-01

    Carbohydrates are candidates for the basis of species-selective interaction of gametes during mammalian fertilization. In this study, we sought to clarify the roles of sugar residues in the species-selective, sperm-oocyte interaction in pigs and cattle. Acrosome-intact porcine and bovine sperm exhibited their strongest binding affinities for β-Gal and α-Man residues, respectively. Porcine-sperm specificity changed from β-Gal to α-Man after the acrosome reaction, while bovine-sperm specificity did not. Binding of acrosome-intact and acrosome-reacted sperm decreased after trypsinization, indicating that the carbohydrate-binding components are proteins. While immature oocytes bound homologous sperm preferentially to heterologous sperm, oocytes matured in vitro bound similar numbers of homologous and heterologous sperm. Lectin staining revealed the aggregation of α-Man residues on the outer surface of the porcine zona during maturation. In both species, zona-free, mature oocytes bound homologous sperm preferentially to heterologous sperm. The lectin-staining patterns of the zona pellucida and zona-free oocytes coincided with the carbohydrate-binding specificities of acrosome-intact and acrosome-reacted sperm, respectively, supporting the involvement of carbohydrates in gamete recognition in pigs and cattle. These results also indicate that sperm-zona pellucida and sperm-oolemma bindings are not strictly species-specific in pigs and cattle, and further suggest that sperm penetration into the zona and/or fusion with oolemma may be species-specific between pigs and cattle.

  11. Endonuclease restriction-mediated real-time polymerase chain reaction: a novel technique for rapid, sensitive and quantitative detection of nucleic-acid sequence

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2016-07-01

    Full Text Available The article reported a novel methodology for real-time PCR analysis of nucleic acids, termed endonuclease restriction-mediated real-time polymerase chain reaction (ET-PCR. Just like PCR, ET-PCR only required one pair of primers. A short sequence (Ss, which was recognized by restriction enzyme BstUI, was attached to the 5’ end of the forward (F or reverse (R PCR primer, and the new F or R primer was named EF or ER. EF/ER was labeled at the 5’ end with a reporter dye and in the middle with a quenching dye. BstUI cleaves the newly synthesized double-stranded terminal sequences (5’ end recognition sequences and their complementary sequences during the extension phase, which separates the reporter molecule from the quenching dye, leading to a gain of fluorescence signal. This process is repeated in each amplification cycle and unaffected the exponential synthesis of the PCR amplification. ET-PCR allowed real-time analysis of single or multiple targets in a single vessel, and provided the reproducible quantitation of nucleic acids. positive results were generated in a relatively short period. The analytical sensitivity and specificity of ETR-PCR were successfully evaluated, detecting down to 250 fg of genomic DNA per tube of target pathogen DNA examined, and the positive results were generated in a relatively short period. Moreover, the practical application of ET-PCR for simultaneous detection of multiple target pathogens was also demonstrated in artificially contaminated blood samples. In conclusion, due to the technique’s simplicity of design, reproducible data and low contamination risk, ET-PCR assay is an appealing alternative to conventional approaches currently used for real-time nucleic acid analysis.

  12. Uvangoletin induces mitochondria-mediated apoptosis in HL-60 cells in vitro and in vivo without adverse reactions of myelosuppression, leucopenia and gastrointestinal tract disturbances.

    Science.gov (United States)

    Zheng, Zhuanzhen; Qiao, Zhenhua; Gong, Rong; Wang, Yalin; Zhang, Yiqun; Ma, Yanping; Zhang, Li; Lu, Yujin; Jiang, Bo; Li, Guoxia; Dong, Chunxia; Chen, Wenliang

    2016-02-01

    This study investigated the cytotoxic effect of uvangoletin on HL-60 cells, and the effects of uvangoletin on myelosuppression, leucopenia, gastrointestinal tract disturbances and the possible cytotoxic mechanisms by using CCK-8, flow cytometry, western blot, xenograft, cyclophosphamide-induced leucopenia, copper sulfate-induced emesis and ethanol-induced gastric mucosal lesions assays. The results of CCK-8, flow cytometry and western blot assays indicated that uvangoletin showed the cytotoxic effect on HL-60 cells and induced the apoptosis of HL-60 cells by downregulating the expression levels of anti-apoptotic proteins (Survivin, Bcl-xl and Bcl-2), upregulating the expression levels of pro-apoptotic proteins (Smac, Bax, Bad, c-caspase-3 and c-caspase-9), and promoting the release of cytochrome c from mitochondria to cytoplasm. Further, the results of xenograft assay suggested that uvangoletin inhibited the HL-60-induced tumor growth without adverse effect on body weight of nude mice in vivo by regulating the expression levels of above apoptotic proteins. The results indicated that the reductions of WBCs count and thighbone marrow granulocytes percentage in cyclophosphamide-induced leucopenia assay, the incubation period and number of emesis in copper sulfate-induced emesis assay and the gastric mucosal lesions in ethanol-induced gastric mucosal lesions assay were not exacerbated or reversed by uvangoletin. In conclusion, the research preliminarily indicated that uvangoletin induced apoptosis of HL-60 cells in vitro and in vivo without adverse reactions of myelosuppression, leucopenia and gastrointestinal tract disturbances, and the pro-apoptotic mechanisms may be related to mitochondria-mediated apoptotic pathway.

  13. Water Mediated Wittig Reactions of Aldehydes in the Teaching Laboratory: Using Sodium Bicarbonate for the in Situ Formation of Stabilized Ylides

    Science.gov (United States)

    Kelly, Michael J. B.; Fallot, Lucas B.; Gustafson, Jeffrey L.; Bergdahl, B. Mikael

    2016-01-01

    The synthesis of alkenes using the Wittig reaction is a traditional part of many undergraduate organic chemistry teaching laboratory curricula. The aqueous medium version of the Wittig reaction presented is a reliable adaptation of this alkene formation reaction as a very safe alternative in the introductory organic chemistry laboratory. The…

  14. Metabolism-dependent mutagenicity of a compound containing a piperazinyl indazole motif: Role of a novel p450-mediated metabolic reaction involving a putative oxaziridine intermediate.

    Science.gov (United States)

    Chen, Hao; Murray, Joel; Kornberg, Brian; Dethloff, Lloyd; Rock, David; Nikam, Sham; Mutlib, Abdul E

    2006-10-01

    Compound 1a (6-chloro-5-{3-[4-(1H-indazol-3-yl)-piperazin-1-yl]-propyl}-3,3-dimethyl-1,3-dihydro-indol-2-one) was mutagenic to Salmonella typhimurium TA98 in the presence of rat liver S9 subcellular fraction. The metabolism of 1a in rat liver S9 or microsomes demonstrated that it underwent a P450-mediated N-deindazolation (loss of indazole ring) as a predominant metabolic pathway. To investigate a possible link between metabolism and mutagenicity, a structural analogue 1b (6-chloro-5-{3-[4-(1H-indazol-3-yl)-piperidin-1-yl]-propyl}-3,3-dimethyl-1,3-dihydro-indol-2-one), the cleaved product 2a (6-chloro-3,3-dimethyl-5-(3-piperazin-1-yl-propyl)-1,3-dihydro-indol-2-one), and the core motif 3a (3-piperazinyl indazole) were evaluated in the Ames assay. It was found that 1b was not mutagenic to Salmonella typhimurium TA98 in the absence or presence of a metabolic activating system. In contrast to 1a, 1b did not undergo the metabolic cleavage (loss of indazole ring). Marginal mutagenicity of 2a to TA98 was observed with rat liver S9, whereas 3a was shown to be a promutagen. It was further demonstrated that 1a inactivated P450 3A, the principle enzyme catalyzing the N-deindazolation reaction, in an NADPH-, time-, and concentration-dependent manner. The kinetics of inactivation was characterized by a K(I) of 8.1 microM and k(inact) of 0.114 min(-1). The differences in mutagenicity between 1a and 1b suggest that a chemical bond extending from the 3-position of the indazole to a heteroatom (as part of another cyclic ring) is a prerequisite for the toxicity. The metabolic process leading to the elimination of the indazole from the rest of the molecule apparently plays a key role in causing mutagenicity. It is postulated that the N-deindazolation of 1a proceeds via an oxaziridine intermediate, the formation of which is indirectly inferred from the presence of benzoic acid in microsomal incubations. Benzoic acid is thought to be derived from the hydrolysis of 3-indazolone, an

  15. Stereoselective Synthesis of trans-Olefins by the Copper-Mediated SN2′ Reaction of Vinyl Oxazines with Grignard Reagents. Asymmetric Synthesis of D-threo-Sphingosines

    OpenAIRE

    Singh, Om V; Han, Hyunsoo

    2007-01-01

    The SN2′ reaction of 6-vinyl-5,6-dihydro-4H-[1,3]oxazines with Grignard reagents in the presence of CuCN was studied, and high trans selectivity for the formation of double bond was observed with a variety of RMgX. The SN2′ reaction, coupled with regioselective asymmetric aminohydroxylation reaction, provided a highly efficient route for the asymmetric synthesis of D-threo-N-acetylsphingosine.

  16. 甲氧滴滴涕对大鼠精子顶体反应的影响%Effect of methoxychlor on rat sperm acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    刘伏祥; 黄平; 文建国; 杨静; 王坤龙

    2007-01-01

    目的:探讨甲氧滴滴涕(methoxychlor, MXC)对雄性大鼠精子顶体反应的影响.方法:在体外培养的精子悬液中加入不同浓度的MXC和孕酮处理,通过精子考马斯亮蓝染色,镜检计数顶体反应型精子的百分率.结果:与空白组比较,单纯经MXC处理组的顶体反应型精子百分率明显增加,另加孕酮的各处理组顶体反应型精子的百分率增加尤为明显,MXC终浓度≤6.25μg/ml的处理组顶体反应型精子百分率不增加.结论:MXC可促进大鼠精子发生顶体反应且与其剂量有关,当MXC终浓度≤6.25μg/ml不诱发顶体反应.MXC能加强孕酮诱发精子顶体反应的作用.

  17. Glycolipid migration from the apical to the equatorial subdomains of the sperm head plasma membrane precedes the acrosome reaction: evidence for a primary capacitation event in boar spermatozoa

    NARCIS (Netherlands)

    Gadella, B.M.; Lopes-Cardozo, M.; Colenbrander, B.; van Goldie, L.M.G.; Gadella, Th.W.J.

    1995-01-01

    In order to extend the static information of immunolabelling sulphogalactolipids in fixed boar spermatozoa, a fluorescent sulphogalactolipid analogue, galactose(3-sulphate)-b1-1¢[( N-lissamine rhodaminyl)-12-aminododecanoyl]-sphingosine, was incorporated into plasma membranes of living spermatozoa a

  18. Effect of heparin, caffeine and calcium ionophore A23187 on in vitro induction of the acrosome reaction of fresh ram spermatozoa

    Directory of Open Access Journals (Sweden)

    K.H. El-Shahat

    2016-04-01

    Conclusion: The best concentration of heparin, caffeine and ionophore A23187 are 75 μg/mL, 1 mg/mL, 1.55 mM/mL for 3, 1, 4 h incubation respectively and can be used for in vitro fertilization in sheep.

  19. The effect of low-level laser irradiation on sperm motility, and integrity of the plasma membrane and acrosome in cryopreserved bovine sperm.

    Directory of Open Access Journals (Sweden)

    Guilherme Henrique C Fernandes

    Full Text Available Freezing changes sperm integrity remarkably. Cryopreservation involves cooling, freezing, and thawing and all these contribute to structural damage in sperm, resulting in reduced fertility potential. Low-level laser irradiation (LLLI could increase energy supply to the cell and cause reactive oxygen species reduction (ROS, contributing to the restoration of oxygen consumption and adenosine triphosphate synthesis (ATP in the mitochondria. Our goal was to analyze the effects of low-level laser irradiation on sperm motility and integrity of the plasma membrane and acrosome in cryopreserved bovine sperm.We analyzed 09 samples of bull semen (Bos taurus indicus, divided into three groups: a control group without laser irradiation, a 4J group subjected to a laser irradiation dose of 4 joules, and a 6J group subjected to dose of 6 joules. Samples were divided for the analysis of cell viability and acrosomal membrane integrity using flow cytometry; another portion was used for motion analysis. Irradiation was performed in petri dishes of 30 mm containing 3 ml of semen by an aluminum gallium indium phosphide laser diode with a wavelength of 660 nm, 30 mW power, and energy of 4 and 6 joules for 80 and 120 seconds respectively. Subsequently, the irradiated and control semen samples were subjected to cryopreservation and analyzed by flow cytometry (7AAD and FITC-PSA using the ISAS--Integrated Semen Analysis System.Flow cytometry showed an increase in the percentage of live sperm cells and acrosome integrity in relation to control cells when subjected to irradiation of low-power laser in two different doses of 4 and 6 joules (p < 0.05. In the analysis of straightness, percentage of cell movement, and motility, a dose of 4 joules was more effective (p < 0.05.We conclude that LLLI may exert beneficial effects in the preservation of live sperm. A dose of 4 joules prior to cryopreservation was more effective than a dose of 6 joules in preserving sperm motility.

  20. Lanthanide-mediated organic synthesis : lanthanide(III) compounds as Lewis acid catalysts and cerium(IV) compounds as reagents for reactions in ionic liquids

    OpenAIRE

    Deleersnyder, Karen

    2007-01-01

    In this PhD project, new procedures were investigated for various important organic reactions. Nowadays, organic procedures should not only result in high reaction yields and purity but moreover they should be designed to be environmentally friendly as well. Therefore, a proper choice of catalyst and solvent is an important aspect. In this study, greener solvents such as ionic liquids, water and rather unhazardous organic solvents were used. Moreover, this PhD research was focused on the ...

  1. Tetra- and mono-organotin reagents in palladium-mediated cross-coupling reactions for the labeling with carbon-11 of PET tracers

    Energy Technology Data Exchange (ETDEWEB)

    Bourdier, T.; Huiban, M.; Sobrio, F.; Perrio, C.; Barre, E. [Groupe de Dev Methodol en Tomographie par Emission de Positons, UMR CEA 2E, Universite deCaen, Centre Cyceron, F-14070 Caen Cedex (France); Fouquet, A.; Huet, A. [Laboratoire de Chimie Organique et Organometallique, UMR CNRS 3802, Univ Bordeaux I, F-33405 Talence Cedex (France)

    2008-07-01

    The palladium-catalyzed cross-coupling reactions between a (trimethylstannyl)arene and [{sup 11}C]methyl iodide (Stille reaction) or between an aryl halide and a [{sup 11}C]monomethyltin reagent issued from Lappert's stannylene, were developed for the synthesis of polyfunctional [{sup 11}C]methyl quinolines and quinoline-imides as potential tracers for positron emission tomography (PET). (authors)

  2. Role of mobile passenger lymphocytes in the rejection of renal and cardiac allografts in the rat. A passenger lymphocyte-mediated graft-versus-host reaction amplifies the host response

    Energy Technology Data Exchange (ETDEWEB)

    van Vrieshilfgaarde, R.; Hermans, P.; Terpstra, J.L.; van Breda Viresman, P.J.

    1980-03-01

    It is demonstrated that passenger lymphocytes migrate out of rat renal allografts into host spleens in a radioresistant fashion. These mobile passenger lymphocytes within BN kidney and heart transplants are immunocompetent, since they elicit a graft-versus-host (GVH) reaction in the spleens of (LEW x BN)F2 hybrid hosts. The greater GVH reaction in (LEW x BN)F1 recipients of BN kidneys reflects the greater number of mobile passenger lymphocytes in the kidney when compared to the heart. The mobile passenger lymphocytes within BN renal allografts also cause a proliferative response in the spleens of the LEW hosts as well as an accelerated rejection of BN renal allografts when compared to BN cardiac allografts, for the differences between BN kidney and heart, both in terms of splenomegaly elicited in LEW as well as tempo of rejection, are abolished by total body x-irradiation of the donor with 900 rad. Results indicate that a mobile passenger lymphocyte mediated GVH reaction in the central lymphoid organs of the host augments the host response to allogenic kidneys and contributes materially to first-set renal allograft rejection; this GVH reaction on the other hand is not conspicuously present in LEW recipients of BN cardiac allografts and has therefore little effect on first-set cardiac allograft rejection.

  3. Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament.

    KAUST Repository

    Fornander, Louise H

    2013-12-03

    The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.

  4. Evidence for a Precursor Complex in C-H Hydrogen Atom Transfer Reactions Mediated by a Manganese(IV) Oxo Complex

    OpenAIRE

    Garcia Bosch, Isaac; Company Casadevall, Anna; Cady, Clyde W.; Styring, Stenbjörn; Browne, Wesley R; Ribas Salamaña, Xavi; Costas Salgueiro, Miquel

    2011-01-01

    HAT trick: [MnIV(OH)2(H,MePytacn)]2+ (A) and [MnIV(O)(OH)(H,MePytacn)]+ (B) differ in their reactions with CH bonds: compound A engages in typical single-step hydrogen atom transfer (HAT) reactions, whereas B first forms a substrate–B encounter complex (C; see scheme). This equilibrium alters the relative CH reactivity from that expected from CH bond dissociation energies Aquest mateix article està publicat a l'edició alemanya d''Angewandte Chemie' (ISSN 0044-8249, EISSN 1521-3757), 2011, ...

  5. Kinetics and thermodynamics of oxidation mediated reaction in L-cysteine and its methyl and ethyl esters in dimethyl sulfoxide-d6 by NMR spectroscopy

    Science.gov (United States)

    Dougherty, Ryan J.; Singh, Jaideep; Krishnan, V. V.

    2017-03-01

    L-Cysteine (L-Cys), L-Cysteine methyl ester (L-CysME) or L-Cysteine ethyl ester (L-CysEE), when dissolved in dimethyl sulfoxide, undergoes an oxidation process. This process is slow enough and leads to nuclear magnetic resonance (NMR) spectral changes that could be monitored in real time. The oxidation mediated transition is modeled as a pseudo-first order kinetics and the thermodynamic parameters are estimated using the Eyring's formulation. L-Cysteine and their esters are often used as biological models due to the remarkable thiol group that can be found in different oxidation states. This oxidation mediated transition is due to the combination of thiol oxidation to a disulfide followed by solvent-induced effects may be relevant in designing cysteine-based molecular models.

  6. Inhibitory effects of whisky congeners on IgE-mediated degranulation in rat basophilic leukemia RBL-2H3 cells and passive cutaneous anaphylaxis reaction in mice.

    Science.gov (United States)

    Itoh, Tomohiro; Tsukane, Mariko; Koike, Minako; Nakamura, Chizu; Ohguchi, Kenji; Ito, Masafumi; Akao, Yukihiro; Koshimizu, Seiichi; Nozawa, Yoshinori; Wakimoto, Toshiyuki; Nukaya, Haruo; Suwa, Yoshihide

    2010-06-23

    Whisky is matured in oak casks. Many nonvolatile substances (whisky congeners, WC) seep from the oak cask during the maturing process. In this study, three antiallergic agents (syringaldehyde, SA; lyoniresinol, Lyo; and ellagic acid, EA) were isolated from WC. Treatment with SA, Lyo, and EA reduced the elevation of intracellular free Ca(2+) concentration ([Ca(2+)]i) and intracellular ROS production caused by FcepsilonRI activation. The inhibitions of the elevation of [Ca(2+)]i and intracellular ROS production by SA and Lyo were mainly due to the suppression of the NADPH oxidase activity and scavenging of the produced radical, respectively. On the other hand, EA inactivated spleen tyrosine kinase and led to the inhibition of the elevation of [Ca(2+)]i and intracellular ROS production. Furthermore, it was found that WC strongly inhibited IgE binding to the FcepsilonRIalpha chain, whereas SA, Lyo, and EA did not indicate this inhibitory effect. These results suggest that WC inhibits allergic reactions through multiple mechanisms. To disclose the in vivo effects of WC, SA, Lyo, and EA, these compounds were administered to type I allergic model mice, and the passive cutaneous anaphylaxis (PCA) reaction was measured. These compounds remarkably suppressed the PCA reaction. Taken together, these findings suggest that WC seemed to be beneficial to ameliorate allergic reactions.

  7. LDA-mediated selective addition reaction of vinylidenecyclopropanes with aldehydes, ketones, and enones: facile synthesis of vinylcyclopropenes, allenols, and 1,3-enynes.

    Science.gov (United States)

    Lu, Jian-Mei; Shi, Min

    2008-05-15

    Highly selective addition reaction of vinylidenecyclopropanes 1 was realized by treatment with LDA in THF and quenching with aldehydes, ketones, and enones. A number of vinylcyclopropenes, allenols, and 1,3-enynes were obtained selectively in moderate to good yields depending on the nature of different electrophiles.

  8. Frequent occurrence of T cell–mediated late reactions revealed by atopy patch testing with hypoallergenic rBet v 1 fragments

    Science.gov (United States)

    Campana, Raffaela; Moritz, Katharina; Marth, Katharina; Neubauer, Angela; Huber, Hans; Henning, Rainer; Blatt, Katharina; Hoermann, Gregor; Brodie, Tess M.; Kaider, Alexandra; Valent, Peter; Sallusto, Federica; Wöhrl, Stefan; Valenta, Rudolf

    2015-01-01

    Background Late allergic reactions are common in the course of allergen-specific immunotherapy and even occur with allergy vaccines with reduced IgE reactivity. Objective We sought to study atopy patch test (APT) reactions and T-cell responses to the recombinant birch pollen allergen Bet v 1 and recombinant hypoallergenic T-cell epitope–containing Bet v 1 fragments in patients with birch pollen allergy with and without atopic dermatitis (AD). Methods A clinical study was conducted in 15 patients with birch pollen allergy with AD (group 1), 5 patients with birch pollen allergy without AD (group 2), 5 allergic patients without birch pollen allergy (group 3), and 5 nonallergic subjects (group 4) by performing skin prick tests and APTs with rBet v 1 and hypoallergenic rBet v 1 fragments. T-cell, cutaneous lymphocyte antigen (CLA)+ and CCR4+ T-cell and cytokine responses were studied by thymidine uptake, carboxyfluorescein diacetate succinimidyl ester staining, and Luminex technology, respectively. Results rBet v 1 and hypoallergenic rBet v 1 fragments induced APT reactions in not only most of the patients with birch pollen allergy with AD (11/15) but also in most of those without AD (4/5). Patients with birch pollen allergy with AD had higher Bet v 1–specific proliferation of CLA+ and CCR4+ T cells compared with patients with birch pollen allergy without AD. There were no differences in Bet v 1–specific CLA+ and CCR4+ proliferation and cytokine secretion in patients with and without APT reactions. Conclusion Hypoallergenic rBet v 1 fragments induce T cell–dependent late reactions not only in patients with birch pollen allergy with AD but also in those without AD, which can be determined based on APT results but not based on in vitro parameters. PMID:26518092

  9. 糖化学中锡介入的选择性反应%Tin-mediated selective reaction in carbohydrate chemistry

    Institute of Scientific and Technical Information of China (English)

    楼鑫; Seamas Cassidy

    2011-01-01

    The structure of complex of dibutylstannylene acetal with sugar revealed the reasons for selective reaction. And the application of method in the various types of chemical reactions such as acylation,alkylation,oxidation,sulfonation and the performance of the selectivity were discussed in detail.%本文从糖锡络合物结构出发,揭示了锡介入方法进行选择性反应的原因.并对该方法在糖化学各类不同类型的反应如酰化,烃化,氧化,磺化所表现的选择性进行了详细的论述.

  10. NaIO4/LiBr-mediated diastereoselective dihydroxylation of olefins: a catalytic approach to the Prevost-Woodward reaction.

    Science.gov (United States)

    Emmanuvel, Lourdusamy; Shaikh, Tanveer Mahammad Ali; Sudalai, Arumugam

    2005-10-27

    [reaction: see text] LiBr catalyzes efficiently the dihydroxylation of alkenes to afford syn and anti diols with excellent diastereoselectivity depending upon the use of NaIO(4) (30 mol %) or PhI(OAc)(2) (1 equiv), respectively, as the oxidants. The oxidation of non-benzylic halides has been achieved for the first time to afford the corresponding diols in excellent yields.

  11. Time-resolved spectroscopic characterization of a novel photodecarboxylation reaction mediated by homolysis of a carbon α-bond in flurbiprofen.

    Science.gov (United States)

    Su, Tao; Ma, Jiani; Wong, Naikei; Phillips, David Lee

    2013-07-18

    Flurbiprofen (Fp), a nonsteroidal anti-inflammatory drug (NSAID) currently in use for arthritis pain relief and in clinical trials for metastatic prostate cancer, can induce photosensitization and phototoxicity upon exposure to sunlight. The mechanisms responsible for Fp phototoxicity are poorly understood and deserve investigation. In this study, the photodecarboxylation reaction of Fp, which has been assumed to underpin its photoinduced side effects, was explored by femtosecond transient absorption (fs-TA), nanosecond transient absorption (ns-TA), and nanosecond time-resolved resonance Raman (ns-TR(3)) spectroscopic techniques in pure acetonitrile (MeCN) solvent. Density functional theory (DFT) calculations were also performed to facilitate the assignments of transient species. The resonance Raman and DFT calculation results reveal that the neutral form of Fp was the predominant species present in MeCN. Analysis of the ultraviolet/visible absorption spectrum and results from TD-DFT calculations indicate that the second excited singlet (S2) can be excited by 266 nm light. Due to its intrinsic instability, S2 rapidly underwent internal conversion (IC) to decay to the lowest lying excited singlet (S1), which was observed in the fs-TA spectra at very early delay times. Intriguingly, three distinct pathways for S1 decay seem to coexist. Specifically, other than fluorescence emission back to the ground state and transformation to the lowest triplet state T1 through intersystem crossing (ISC), the homolysis of the carbon α-bond decarboxylation reaction proceeded simultaneously to give rise to two radical species, one being carboxyl and another being the residual, denoted as FpR. The coexistence of the triplet Fp (T1) and FpR species was verified by means of TR(3) spectra along with ns-TA spectra. As a consequence of its apparent high reactivity, the FpR intermediate was observed to undergo oxidation under oxygen-saturated conditions to yield another radical species

  12. Synthesis of robust hierarchical silica monoliths by surface-mediated solution/precipitation reactions over different scales: designing capillary microreactors for environmental applications.

    Science.gov (United States)

    García-Aguilar, J; Miguel-García, I; Berenguer-Murcia, Á; Cazorla-Amorós, D

    2014-12-24

    A synthetic procedure to prepare novel materials (surface-mediated fillings) based on robust hierarchical monoliths is reported. The methodology includes the deposition of a (micro- or mesoporous) silica thin film on the support followed by growth of a porous monolithic SiO2 structure. It has been demonstrated that this synthesis is viable for supports of different chemical nature with different inner diameters without shrinkage of the silica filling. The formation mechanism of the surface-mediated fillings is based on a solution/precipitation process and the anchoring of the silica filling to the deposited thin film. The interaction between the two SiO2 structures (monolith and thin film) depends on the porosity of the thin film and yields composite materials with different mechanical stability. By this procedure, capillary microreactors have been prepared and have been proved to be highly active and selective in the total and preferential oxidation of carbon monoxide (TOxCO and PrOxCO).

  13. The effects of phorbol ester activation and reactive oxygen species scavengers on the macrophage-mediated foreign body reaction to polyurethanes.

    Science.gov (United States)

    McBane, Joanne E; Matheson, Loren A; Santerre, J Paul; Labow, Rosalind S

    2009-12-15

    Phorbol myristate acetate, a protein kinase C activator, inhibited monocyte-derived macrophage (MDM)-mediated degradation of aliphatic (HDI) polycarbonate-based polyurethanes but not degradation of the aromatic polycarbonate-based polyurethane (MDI). The objectives of this study were to determine if reactive oxygen species are involved in the phorbol myristate acetate effect on esterase activity and MDM-mediated polycarbonate-based polyurethane degradation and to find a good marker of material-initiated activation of MDM. The phorbol myristate acetate-dependent effects of the material chemistry on cell activation and degradation were evaluated by adding reactive oxygen species scavengers, catalase plus superoxide dismutase to MDM and assaying possible markers of MDM activation: esterase activity, acid phosphatase activity, and high molecular weight group box 1 protein (HMGB1). All treatments reduced the esterase activity in MDM on HDI but not in MDM on MDI. Acid phosphatase was inhibited in MDM to varying degrees on all surfaces by phorbol myristate acetate or catalase plus superoxide dismutase either alone or together. Secretion of HMGB1 from MDM on HDI431 was higher than MDI; however only secretion from MDM on HDI was inhibited by phorbol myristate acetate. In MDM on HDI, catalase plus superoxide dismutase reduced intracellular HMGB1 levels +/- phorbol myristate acetate; whereas, catalase, superoxide dismutase plus phorbol myristate acetate increased intracellular HMGB1 in MDM on MDI, suggesting that esterase and HMGB1 are more specific markers of activation than acid phosphatase. Manipulation of signaling pathways may provide insight surrounding the mechanism of activation for oxidative and/or hydrolytic degradative pathways in the MDM response to material surface chemistry.

  14. Adrenergic System Activation Mediates Changes in Cardiovascular and Psychomotoric Reactions in Young Individuals after Red Bull© Energy Drink Consumption

    Directory of Open Access Journals (Sweden)

    Ana Cavka

    2015-01-01

    Full Text Available Objectives. To assess the effect of Red Bull© on (1 blood glucose and catecholamine levels, (2 cardiovascular and respiratory function changes before, during, and after exercise, (3 reaction time, (4 cognitive functions, and (5 response to mental stress test and emotions in young healthy individuals (N=38. Methods. Heart rate (HR and arterial blood pressure (ABP, blood glucose, adrenaline, and noradrenalin plasma levels were measured before and after Red Bull© intake. Participants were subjected to 4 different study protocols by randomized order, before and 30 minutes after consumption of 500 mL of Red Bull©. Results. Mean ABP and HR were significantly increased at rest after Red Bull© intake. Blood glucose level and plasma catecholamine levels significantly increased after Red Bull© consumption. Heart rate, respiration rate, and respiratory flow rate were significantly increased during exercise after Red Bull© consumption compared to control condition. Intake of Red Bull© significantly improved reaction time, performance in immediate memory test, verbal fluency, and subject’s attention as well as performance in mental stress test. Conclusion. This study demonstrated that Red Bull© has beneficial effect on some cognitive functions and effect on cardiovascular and respiratory system at rest and during exercise by increasing activity of the sympathetic nervous system.

  15. From dihydrated iron(III) phosphate to monohydrated ammonium-iron(II) phosphate: Solvothermal reaction mediated by acetone-urea mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Alfonso, Belen F., E-mail: mbafernandez@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Trobajo, Camino [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Pique, Carmen [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Garcia, Jose R. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain)

    2012-12-15

    By reaction between synthetic phosphosiderite FePO{sub 4}{center_dot}2H{sub 2}O, urea (NH{sub 2}){sub 2}CO, and acetone (CH{sub 3}){sub 2}CO, we report a novel solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2}, is also described. The obtained product is a function of the reaction time and the N/P molar ratio in the reagent mixture, and the existence of structural memory in the dissolution-precipitation processes is discussed. Below 25 K, NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O behaves magnetically in a complex way, because both ferromagnetic and antiferromagnetic signals are superimposed, suggesting the existence of a canting of iron(II) magnetic moments. - Graphical abstract: Solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O is presented. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2} as a function of the N/P molar ratio in the reagent mixture and the reaction time, is also described. Highlights: Black-Right-Pointing-Pointer Solvothermal synthesis of NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O from an Fe(III) phosphate: reduction process. Black-Right-Pointing-Pointer Formation of two intermediate metastable phases: phase diagram. Black-Right-Pointing-Pointer Thermal decomposition in two steps: mass loss of both water and ammonia. Black-Right-Pointing-Pointer Magnetic behaviour: AF+constant spontaneous magnetization.

  16. Doc2b promotes GLUT4 exocytosis by activating the SNARE-mediated fusion reaction in a calcium- and membrane bending-dependent manner.

    Science.gov (United States)

    Yu, Haijia; Rathore, Shailendra S; Davis, Eric M; Ouyang, Yan; Shen, Jingshi

    2013-04-01

    The glucose transporter GLUT4 plays a central role in maintaining body glucose homeostasis. On insulin stimulation, GLUT4-containing vesicles fuse with the plasma membrane, relocating GLUT4 from intracellular reservoirs to the cell surface to uptake excess blood glucose. The GLUT4 vesicle fusion reaction requires soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) as the core fusion engine and a group of regulatory proteins. In particular, the soluble C2-domain factor Doc2b plays a key role in GLUT4 vesicle fusion, but its molecular mechanism has been unclear. Here we reconstituted the SNARE-dependent GLUT4 vesicle fusion in a defined proteoliposome fusion system. We observed that Doc2b binds to GLUT4 exocytic SNAREs and potently accelerates the fusion kinetics in the presence of Ca(2+). The stimulatory activity of Doc2b requires intact Ca(2+)-binding sites on both the C2A and C2B domains. Using electron microscopy, we observed that Doc2b strongly bends the membrane bilayer, and this membrane-bending activity is essential to the stimulatory function of Doc2b in fusion. These results demonstrate that Doc2b promotes GLUT4 exocytosis by accelerating the SNARE-dependent fusion reaction by a Ca(2+)- and membrane bending-dependent mechanism. Of importance, certain features of Doc2b function appear to be distinct from how synaptotagmin-1 promotes synaptic neurotransmitter release, suggesting that exocytic Ca(2+) sensors may possess divergent mechanisms in regulating vesicle fusion.

  17. Intracytoplasmic Sperm Injection Fertilization Rate Does Not-Depend on the Proportion of Round-headed Sperm, Small acrosomal Sperm, or Morphologically Normal Sperm in Patients with Partial Globozoospermia

    Institute of Scientific and Technical Information of China (English)

    Ling-Ying Jiang; Ling-Yun Yang; Xiao-Mei Tong; Hai-Yan Zhu; Ya-Mei Xue; Wen-Zhi Xu; Yang Yang

    2015-01-01

    Background:Generally,intracytoplasmic sperm injection (ICSI) may be the preferable method to treat partial globozoospermia,but whether there exist some correlations between ICSI fertilization rate and the proportion of round-headed sperm or morphologically normal sperm remains open.This study was to explore the correlation between ICSI fertilization rate and the sperm morphology in patients with partial globozoospermia.Methods:Thirty-four patients diagnosed with partial globozoospermia accepted the following assisted fertilization treatments-2 cases accepted in-vitro fertilization (IvF) alone,26 cases accepted ICSI alone,and 6 accepted split IVF/ICSI.Detailed morphological characteristics were described using Diff-Quik rapid staining.Sixty cases accepting IVF or ICSI treatment in our reproductive center were considered as the control group after being matched by relevant criteria.Fertilization rate,embryo quality,embryo implantation rate and clinical pregnancy rate were calculated.Results:Besides very high proportion of round-headed sperm,partial globozoospermia also showed very high proportion of small-acrosomal sperm and very low proportion of morphologically normal sperm.Fertilization rate of IVF (IVF alone plus split IVF) was very low in partial globozoospermia (25.4% ± 17.4%),but ICSI (ICSI alone plus split ICSI) achieved satisfying fertilization rate compared with the control group (66.2% ± 22.5% vs.68.8% ± 29.4%,P > 0.05).In patients with partial globozoospermia,there were no correlations between ICSI fertilization rate and the proportion of round-headed sperm,small-acrosomal sperm,or morphologically normal sperm.Conclusions:There was high proportion of small-acrosomal sperm in partial globozoospermia.For patients with partial globozoospermia,ICSI is more preferable than IVF.ICSI fertilization rate does not depend on the proportion of round-headed sperm,small-acrosomal sperm,or morphologically normal sperm.

  18. Selective amplification of cDNA sequence from total RNA by cassette-ligation mediated polymerase chain reaction (PCR): application to sequencing 6.5 kb genome segment of hantavirus strain B-1.

    Science.gov (United States)

    Isegawa, Y; Sheng, J; Sokawa, Y; Yamanishi, K; Nakagomi, O; Ueda, S

    1992-12-01

    A method, referred to as cassette-ligation mediated polymerase chain reaction (PCR), has been developed to permit selective and specific amplification of cDNA sequence from total cellular RNA. This technique comprises (i) digestion of cDNA with multiple restriction enzymes, (ii) ligation of cleavage products to double-stranded DNA cassettes possessing a corresponding restriction site and (iii) amplification of cassette-ligated restriction fragments containing a short, known sequence (but not all the other ligation products) by PCR using the specific and cassette primers; the specific primer is designed to prime synthesis from the known sequence of the cDNA whereas the cassette primer anneals to one strand of the cassette. Sequencing from the cassette primer provides information to design a new primer for the next walking step. The amplified cDNA fragments are often larger than the maximum DNA fragments (500-600 bp) that can be sequenced without the need of synthesizing internal sequencing primer. Each of such large cDNA fragments is dissected into smaller DNA fragments by repeating cassette-ligation mediated PCR exploiting different restriction sites and different sets of cassette primers. This dissection process reduces the number of specific primers to a minimum, thereby increasing the speed of sequencing and minimizing the overall cost. We have successfully applied this cDNA walking and sequencing by the cassette-ligation mediated PCR to the sequencing of an entire 6.5 kb genome segment of hantavirus strain B-1.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Utility of Loop-mediated Isothermal Amplification Assay, Polymerase Chain Reaction, and ELISA for Diagnosis of Leptospirosis in South Indian Patients

    Science.gov (United States)

    Sengupta, Mallika; Prabhakar, Abhilash Kundavaram Paul; Satyendra, Sowmya; Thambu, David; Abraham, Ooriapadickal Cherian; Balaji, Veeraraghavan; Chen, Hua-Wei; Chao, Chien-Chung; Ching, Wei-Mei; Prakash, John Antony Jude

    2017-01-01

    Background: Leptospirosis is a zoonotic disease which requires laboratory diagnosis for confirmation. Materials and Methods: In this study serum samples from adults with acute undifferentiated fever (duration ≤15 days) were tested for IgM antibodies to Leptospira by ELISA, PCR for rrs gene and loop-mediated isothermal amplification (LAMP) assay for LipL32 and LipL41. Results: Among the 150 sera tested, three were positive by PCR, LAMP and IgM ELISA/modified Faines’ criteria, two by only PCR; seven only by LAMP assay and forty fulfilled modified Faine's criteria (illness clinically compatible and IgM ELISA positive for leptospirosis). Clinical correlation revealed renal compromise, low platelet count and severe jaundice were significantly related to leptospirosis (P < 0.05). Conclusion: This study suggests that LAMP assay could be useful for diagnosis of leptospirosis during the 1st week of illness whereas IgM ELISA forms the mainstay of diagnosis from the 2nd week onward. Further studies especially community based, comparing ELISA, PCR, LAMP, culture and microscopic agglutination test are required to evaluate the veracity of these findings.

  20. Utility of loop-mediated isothermal amplification assay, polymerase chain reaction, and elisa for diagnosis of leptospirosis in South Indian patients

    Directory of Open Access Journals (Sweden)

    Mallika Sengupta

    2017-01-01

    Full Text Available Background: Leptospirosis is a zoonotic disease which requires laboratory diagnosis for confirmation. Materials and Methods: In this study serum samples from adults with acute undifferentiated fever (duration ≤15 days were tested for IgM antibodies to Leptospira by ELISA, PCR for rrs gene and loop-mediated isothermal amplification (LAMP assay for LipL32 and LipL41. Results: Among the 150 sera tested, three were positive by PCR, LAMP and IgM ELISA/modified Faines' criteria, two by only PCR; seven only by LAMP assay and forty fulfilled modified Faine's criteria (illness clinically compatible and IgM ELISA positive for leptospirosis. Clinical correlation revealed renal compromise, low platelet count and severe jaundice were significantly related to leptospirosis (P < 0.05. Conclusion: This study suggests that LAMP assay could be useful for diagnosis of leptospirosis during the 1st week of illness whereas IgM ELISA forms the mainstay of diagnosis from the 2nd week onward. Further studies especially community based, comparing ELISA, PCR, LAMP, culture and microscopic agglutination test are required to evaluate the veracity of these findings.

  1. Microwave Mediated Organic Reaction: A Convenient Approach for Rapid and Efficient Synthesis of Biologically Active Substituted 1,3-Dihydro-2H-indol-2-one Derivatives

    Directory of Open Access Journals (Sweden)

    Jnyanaranjan Panda

    2013-01-01

    Full Text Available A simple and efficient method has been developed for the synthesis of 1,3-dihydro-2H-indol-2-one derivatives using microwave irradiation technique. By taking advantage of the efficient source of energy of microwave, compound libraries for lead generation and optimization can be assembled in a fraction of time. In the present work, first the Schiff’s bases are synthesized by reaction of isatin with substituted anilines in the presence of acetic acid under microwave heating. Then the condensation of Schiff bases with different secondary amines in the presence of formaldehyde produces Mannich bases. The newly synthesized Mannich bases were characterized by means of spectral data and then evaluated for anthelmintic activity against Pheretima posthuma (Indian earthworm and compared with standard albendazole. The compounds were evaluated at the concentrations of 10, 20, and 50 mg/mL. The effect of the standard drug albendazole at 10 mg/mL was also evaluated. The results of the present study indicate that some of the test compounds significantly demonstrated paralysis and also caused death of worms in a dose-dependent manner.

  2. Roles of MAS-related G protein coupled receptor-X2 (MRGPRX2) on mast cell-mediated host defense, pseudoallergic drug reactions and chronic inflammatory diseases

    Science.gov (United States)

    Subramanian, Hariharan; Gupta, Kshitij; Ali, Hydar

    2016-01-01

    Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity and wound healing. MCs are, however, best known for their roles in allergic and inflammatory diseases such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis and asthma. In addition to the high affinity IgE receptor (FcεRI), MCs express numerous G protein coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and are the most common targets of drug therapy. Antimicrobial host defense peptides (HDPs), neuropeptides (NPs), major basic protein (MBP), eosinophil peroxidase (EPO) and many FDA approved peptidergic drugs activate human MCs via a novel GPCR known as MAS-related G protein coupled receptor-X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on plasma membrane and intracellular sites and their selective expression in MCs. In this article, we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch and chronic inflammatory diseases such as urticaria and asthma. We propose that HDPs that kill microbes directly and activate MCs via MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, monoclonal antibodies or small molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders. PMID:27448446

  3. The mechanism of the modified Ullmann reaction

    NARCIS (Netherlands)

    Sperotto, Elena; Klink, Gerard P.M. van; Koten, Gerard van; Vries, Johannes G. de

    2010-01-01

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) ma

  4. Isomeric [RuCl2(dmso)2(indazole)2] complexes: ruthenium(II)-mediated coupling reaction of acetonitrile with 1H-indazole.

    Science.gov (United States)

    Reisner, Erwin; Arion, Vladimir B; Rufińska, Anna; Chiorescu, Ion; Schmid, Wolfgang F; Keppler, Bernhard K

    2005-07-21

    Reaction of the antitumor complex trans-[Ru(III)Cl4(Hind)2]- (Hind = indazole) with an excess of dimethyl sulfoxide (dmso) in acetone afforded the complex trans,trans,trans-[Ru(II)Cl2(dmso)2(Hind)2] (1). Two other isomeric compounds trans,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (2) and cis,cis,cis-[Ru(II)Cl2(dmso)2(Hind)2] (3) have been obtained on refluxing cis-[Ru(II)Cl(2)(dmso)(4)] with 2 equiv. of indazole in ethanol and methanol, respectively. Isomers 1 and 2 react with acetonitrile yielding the complexes trans-[Ru(II)Cl2(dmso)(Hind){HN=C(Me)ind}].CH3CN (4.CH3CN) and trans,cis-[Ru(II)Cl2(dmso)2{HN=C(Me)ind}].H2O (5.H2O), respectively, containing a cyclic amidine ligand resulting from insertion of the acetonitrile C triple bond N group in the N1-H bond of the N2-coordinated indazole ligand in the nomenclature used for 1H-indazole. These are the first examples of the metal-assisted iminoacylation of indazole. The products isolated have been characterized by elemental analysis, IR spectroscopy, UV-vis spectroscopy, electrospray mass-spectrometry, thermogravimetry, differential scanning calorimetry, 1H NMR spectroscopy, and solid-state 13C CP MAS NMR spectroscopy. The isomeric structures of 1-3 and the presence of a chelating amidine ligand in 4 and 5 have been confirmed by X-ray crystallography. The electrochemical behavior of 1-5 and the formation of 5 have been studied by cyclic voltammetry.

  5. DNA and DNA computation based on to ehold-mediated strand-displacement reactions%DNA及基于DNA链替换反应的分子计算∗

    Institute of Scientific and Technical Information of China (English)

    肖石燕; 梁好均

    2016-01-01

    DNA是生物遗传信息的载体,同时也是一种理想的生物相容材料。单链黏性末端(toehold)协助的链替换反应是DNA常温纳米技术的基础。利用DNA的碱基互补特性和碱基序列的可编程性,人们可以基于DNA链替换反应构建分子机器并对其运转进行精确调控,实现各种复杂分子计算。本文回顾了近年来DNA结构和力学性质方面的研究进展,探讨DNA链替换反应的微观理解,介绍DNA分子计算领域的最新成果,以及它在DNA恒温自组装等方面的应用。%Other than being a carrier of the code of life, DNA can also be used as a kind of ideal biomaterial with good biocom-patibility. Considering the critical role of DNA less than 150 base pairs (bp) in cellular processes such as regulated gene expression, quantifying the intrinsic bend ability of DNA on a sub-persistence length scale is essential to understanding its molecular functions and the DNA-protein interaction. From the classical point of view, double-stranded DNA is assumed to be stiff and can be treated by semi-flexible chain, but recent studies have yielded contradictory results. A lot of studies tried to prove that the worm-like chain model can be used to fully describe DNA chain. However, recent theoretical and experimental studies indicated that DNA exhibits high flexibility on a short length scale, which cannot be described by the worm-like chain model. Further studies are needed to address the extreme flexibility of DNA on a short length scale. On the basis of the predictability of the double helical structure and the Watson-Crick binding thermodynamics for DNA, a class of DNA reactions can be defined, called toehold-mediated strand-displacement re-action, in which one complementary single-stranded DNA sequence first binds to the dangling toehold domain of the substrate in a pre-hybridized double-stranded DNA, then triggers the strand-displacement reaction, and finally results in the

  6. Intracellular calcium movements of boar spermatozoa during 'in vitro' capacitation and subsequent acrosome exocytosis follow a multiple-storage place, extracellular calcium-dependent model.

    Science.gov (United States)

    Yeste, M; Fernández-Novell, J M; Ramió-Lluch, L; Estrada, E; Rocha, L G; Cebrián-Pérez, J A; Muiño-Blanco, T; Concha, I I; Ramírez, A; Rodríguez-Gil, J E

    2015-07-01

    This work analysed intracellular calcium stores of boar spermatozoa subjected to 'in vitro' capacitation (IVC) and subsequent progesterone-induced acrosome exocytosis (IVAE). Intracellular calcium was analysed through two calcium markers with different physico-chemical properties, Fluo-3 and Rhod-5N. Indicative parameters of IVC and IVAE were also evaluated. Fluo-3 was located at both the midpiece and the whole head. Rhod-5N was present at the sperm head. This distribution did not change in any of the assayed conditions. Induction of IVC was concomitant with an increase in both head and midpiece Ca(2+) signals. Additionally, while IVC induction was concurrent with a significant (p sperm membrane permeability, no significant changes were observed in O2 consumption and ATP levels. Incubation of boar spermatozoa in the absence of calcium showed a loss of both Ca(2+) labellings concomitantly with the sperm's inability to achieve IVC. The absence of extracellular calcium also induced a severe decrease in the percentage of spermatozoa exhibiting high mitochondrial membrane potential (hMMP). The IVAE was accompanied by a fast increase in both Ca(2+) signalling in control spermatozoa. These peaks were either not detected or much lessened in the absence of calcium. Remarkably, Fluo-3 marking at the midpiece increased after progesterone addition to sperm cells incubated in a medium without Ca(2+) . The simultaneous addition of progesterone with the calcium chelant EGTA inhibited IVAE, and this was accompanied by a significant (p boar spermatozoa present different calcium deposits with a dynamic equilibrium among them and with the extracellular environment. Additionally, the modulation role of the intracellular calcium in spermatozoa function seems to rely on its precise localization in boar spermatozoa.

  7. Intercultural Mediation

    OpenAIRE

    Dragos Marian Radulescu; Denisa Mitrut

    2012-01-01

    The Intercultural Mediator facilitates exchanges between people of different socio-cultural backgrounds and acts as a bridge between immigrants and national and local associations, health organizations, services and offices in order to foster integration of every single individual. As the use mediation increases, mediators are more likely to be involved in cross-cultural mediation, but only the best mediators have the opportunity to mediate cross border business disputes or international poli...

  8. Pathophysiology of hemolytic transfusion reactions.

    Science.gov (United States)

    Davenport, Robertson D

    2005-07-01

    Hemolytic transfusion reactions (HTR) are systemic reactions provoked by immunologic red blood cell (RBC) incompatibility. Clinical and experimental observations of such reactions indicate that they proceed through phases of humoral immune reaction, activation of phagocytes, productions of cytokine mediators, and wide-ranging cellular responses. HTR have many features in common with the systemic inflammatory response syndrome (SIRS). Knowledge of the pathophysiologic mechanisms in HTR suggest that newer biological agents that target complement intermediates or proinflammatory cytokines may be effective agents in the treatment of severe HTRs.

  9. Reaction Graph

    Institute of Scientific and Technical Information of China (English)

    傅育熙

    1998-01-01

    The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.

  10. Heat Sensing Receptor TRPV1 Is a Mediator of Thermotaxis in Human Spermatozoa

    Science.gov (United States)

    Menegazzo, Massimo; Magagna, Sabina; Di Nisio, Andrea; Šabović, Iva; Rocca, Maria Santa; Scattolini, Valentina; Filippi, Andrea; Foresta, Carlo

    2016-01-01

    The molecular bases of sperm thermotaxis, the temperature-oriented cell motility, are currently under investigation. Thermal perception relies on a subclass of the transient receptor potential [TRP] channels, whose member TRPV1 is acknowledged as the heat sensing receptor. Here we investigated the involvement of TRPV1 in human sperm thermotaxis. We obtained semen samples from 16 normozoospermic subjects attending an infertility survey programme, testis biopsies from 6 patients with testicular germ cell cancer and testis fine needle aspirates from 6 patients with obstructive azoospermia undergoing assisted reproductive technologies. Expression of TRPV1 mRNA was assessed by RT-PCR. Protein expression of TRPV1 was determined by western blot, flow cytometry and immunofluorescence. Sperm motility was assessed by Sperm Class Analyser. Acrosome reaction, apoptosis and intracellular-Ca2+ content were assessed by flow cytometry. We found that TRPV1 mRNA and protein were highly expressed in the testis, in both Sertoli cells and germ-line cells. Moreover, compared to no-gradient controls at 31°C or 37°C (Ctrl 31°C and Ctrl 37°C respectively), sperm migration towards a temperature gradient of 31–37°C (T gradient) in non-capacitated conditions selected a higher number of cells (14,9 ± 4,2×106 cells T gradient vs 5,1± 0,3×106 cells Ctrl 31°C and 5,71±0,74×106 cells Ctrl 37°C; P = 0,039). Capacitation amplified the migrating capability towards the T gradient. Sperms migrated towards the T gradient showed enriched levels of both TRPV1 protein and mRNA. In addition, sperm cells were able to migrate toward a gradient of capsaicin, a specific agonist of TRPV1, whilst capsazepine, a specific agonist of TRPV1, blocked this effect. Finally, capsazepine severely blunted migration towards T gradient without abolishing. These results suggest that TRPV1 may represent a facilitating mediator of sperm thermotaxis. PMID:27992447

  11. Drug hypersensitivity reactions involving skin.

    Science.gov (United States)

    Hausmann, Oliver; Schnyder, Benno; Pichler, Werner J

    2010-01-01

    Immune reactions to drugs can cause a variety of diseases involving the skin, liver, kidney, lungs, and other organs. Beside immediate, IgE-mediated reactions of varying degrees (urticaria to anaphylactic shock), many drug hypersensitivity reactions appear delayed, namely hours to days after starting drug treatment, showing a variety of clinical manifestations from solely skin involvement to fulminant systemic diseases which may be fatal. Immunohistochemical and functional studies of drug-specific T cells in patients with delayed reactions confirmed a predominant role for T cells in the onset and maintenance of immune-mediated delayed drug hypersensitivity reactions (type IV reactions). In these reactions, drug-specific CD4+ and CD8+ T cells are stimulated by drugs through their T cell receptors (TCR). Drugs can stimulate T cells in two ways: they can act as haptens and bind covalently to larger protein structures (hapten-carrier model), inducing a specific immune response. In addition, they may accidentally bind in a labile, noncovalent way to a particular TCR of the whole TCR repertoire and possibly also major histocompatibility complex (MHC)-molecules - similar to their pharmacologic action. This seems to be sufficient to reactivate certain, probably in vivo preactivated T cells, if an additional interaction of the drug-stimulated TCR with MHC molecules occurs. The mechanism was named pharmacological interaction of a drug with (immune) receptor and thus termed the p-i concept. This new concept may explain the frequent skin symptoms in drug hypersensitivity to oral or parenteral drugs. Furthermore, the various clinical manifestations of T cell-mediated drug hypersensitivity may be explained by distinct T cell functions leading to different clinical phenotypes. These data allowed a subclassification of the delayed hypersensitivity reactions (type IV) into T cell reactions which, by releasing certain cytokines and chemokines, preferentially activate and recruit

  12. Metal-catalyzed asymmetric aldol reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Luiz C.; Lucca Junior, Emilio C. de; Ferreira, Marco A. B.; Polo, Ellen C., E-mail: ldias@iqm.unicamp.br [Universidade de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica

    2012-12-15

    The aldol reaction is one of the most powerful and versatile methods for the construction of C-C bonds. Traditionally, this reaction was developed in a stoichiometric version; however, great efforts in the development of chiral catalysts for aldol reactions were performed in recent years. Thus, in this review article, the development of metal-mediated chiral catalysts in Mukaiyama-type aldol reaction, reductive aldol reaction and direct aldol reaction are discussed. Moreover, the application of these catalysts in the total synthesis of complex molecules is discussed. (author)

  13. Mediatized Humanitarianism

    DEFF Research Database (Denmark)

    Vestergaard, Anne

    2014-01-01

    The article investigates the implications of mediatization for the legitimation strategies of humanitarian organizations. Based on a (full population) corpus of ~400 pages of brochure material from 1970 to 2007, the micro-textual processes involved in humanitarian organizations' efforts to legiti......The article investigates the implications of mediatization for the legitimation strategies of humanitarian organizations. Based on a (full population) corpus of ~400 pages of brochure material from 1970 to 2007, the micro-textual processes involved in humanitarian organizations' efforts...... legitimation by accountancy, legitimation by institutionalization, and legitimation by compensation. The analysis relates these changes to a problem of trust associated with mediatization through processes of mediation....

  14. [Mechanisms of cutaneous drug reactions].

    Science.gov (United States)

    Vaillant, L

    2000-06-15

    Two main mechanisms, pharmacologic and immunoallergic, are responsible for cutaneous reactions to drugs. Pharmacologic mechanisms can be predictable (overdosage, cumulative or delayed toxicity, adverse effects) or unpredictable (idiosyncratic, intolerance, or anaphylactic reaction). Immunoallergic mechanisms can be mediated by IgE (some types of urticaria and anaphylactic shock), due to circulating immune complexes (leukocytoclastic vasculitis, serum sickness-type reactions) or mediated by lymphocytes (exanthema, Lyell's syndrome, fixed pigmented erythema, photosensitization). The diagnostic work-up varies according to the causative mechanism. When the reaction is predictable, the responsible drug can be identified according to the data in the present bibliography. When the reaction is immunologic, only the chronologic sequence of events can identify the responsible drug. The risk of recurrence with an identical or related molecule also varies according to the causative mechanism. For urticaria, diagnosis and the risk of recurrence differ according to whether the cause is allergic (mediated by IgE or urticarial vasculitis) or is pharmacologic (urticaria due to aspirin or to conversion enzyme inhibitors).

  15. Adverse reactions to drug additives.

    Science.gov (United States)

    Simon, R A

    1984-10-01

    There is a long list of additives used by the pharmaceutical industry. Most of the agents used have not been implicated in hypersensitivity reactions. Among those that have, only reactions to parabens and sulfites have been well established. Parabens have been shown to be responsible for rare immunoglobulin E-mediated reactions that occur after the use of local anesthetics. Sulfites, which are present in many drugs, including agents commonly used to treat asthma, have been shown to provoke severe asthmatic attacks in sensitive individuals. Recent studies indicate that additives do not play a significant role in "hyperactivity." The role of additives in urticaria is not well established and therefore the incidence of adverse reactions in this patient population is simply not known. In double-blind, placebo-controlled studies, reactions to tartrazine or additives other than sulfites, if they occur at all, are indeed quite rare for the asthmatic population, even for the aspirin-sensitive subpopulation.

  16. Current rectification by mediating electroactive polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ybarra, Gabriel; Moina, Carlos [Centro de Investigacion sobre Electrodeposicion y Procesos Superficiales, Instituto Nacional de Tecnologia Industrial, CC 157, (1650) San Martin (Argentina); Florit, M. Ines [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, (1900) La Plata (Argentina); Posadas, Dionisio [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, (1900) La Plata (Argentina)], E-mail: dposadas@inifta.unlp.edu.ar

    2008-04-20

    In this work we briefly review the theoretical basis for the electrochemical rectification in mediated redox reactions at redox polymer modified electrodes. Electrochemical rectification may have two distinct origins. It is either caused by a slow kinetics of the reaction between the external redox couple and the mediator or it is originated by a slow electronic transport within the film under an unfavorable thermodynamic condition. We show experimental results for the redox mediation reaction of poly(o-aminophenol) (POAP) on the Fe{sup 2+/3+} and on the Fe(CN){sub 6}{sup 3-/4-} redox couples in solution that prove the proposed mechanisms of electrochemical rectification.

  17. Complex Mediation

    DEFF Research Database (Denmark)

    Bødker, Susanne; Andersen, Peter Bøgh

    2005-01-01

    This article has its starting point in a large number of empirical findings regarding computer-mediated work. These empirical findings have challenged our understanding of the role of mediation in such work; on the one hand as an aspect of communication and cooperation at work and on the other hand...... as an aspect of human engagement with instruments of work. On the basis of previous work in activity-theoretical and semiotic human—computer interaction, we propose a model to encompass both of these aspects. In a dialogue with our empirical findings we move on to propose a number of types of mediation...... that have helped to enrich our understanding of mediated work and the design of computer mediation for such work....

  18. Capture reactions

    NARCIS (Netherlands)

    Endt, P.M.

    1956-01-01

    Capture reactions will be considered here from the viewpoint of the nuclear spectroscopist. Especially important to him are the capture of neutrons, protons, and alpha particles, which may proceed through narrow resonances, offering a well defined initial state for the subsequent deexcitation proces

  19. Síntese de 2-iodobenzamidas e 3-(iodoacetamidobenzamidas ligadas à D-galactose e suas reações de carbociclização radicalar mediadas por hidreto de tri-n-butilestanho Synthesis of 2-iodobenzamides and 3-(iodoacetamidobenzamides linked to D-galactose and their tri-n-butyltin hydride-mediated radical carbocyclization reactions

    Directory of Open Access Journals (Sweden)

    Daniel Henriques Soares Leal

    2009-01-01

    Full Text Available Starting from methyl 6-O-allyl-4-azido-2,3-di-O-benzyl-4-deoxy-α-D-galactopyranoside, four new derivatives containing 2-iodobenzamido and 3-(iodoacetamidobenzamido groups were synthesized. These four compounds were submitted to tri-n-butyltin hydride mediated radical cyclization reactions, resulting in two macrolactams from 11- and 15-endo aryl radical cyclization. The corresponding four hydrogenolysis products were also obtained. The structures of the new compounds were elucidated by ¹H and 13C NMR spectroscopy, DEPT, COSY, HMQC and HMBC experiments.

  20. The mechanism of the modified Ullmann reaction

    OpenAIRE

    Sperotto, Elena; Klink, Gerard P.M. van; van Koten, Gerard; Vries, Johannes G. de

    2010-01-01

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of the...

  1. Eicosanoids mediate insect hemocyte migration

    Science.gov (United States)

    Hemocyte chemotaxis toward infection and wound sites is an essential component of insect defense reactions, although the biochemical signal mechanisms responsible for mediating chemotaxis in insect cells are not well understood. Here we report on the outcomes of experiments designed to test the hyp...

  2. Natural generalized mirage mediation

    Science.gov (United States)

    Baer, Howard; Barger, Vernon; Serce, Hasan; Tata, Xerxes

    2016-12-01

    In the supersymmetric scenario known as mirage mediation (MM), the soft supersymmetry (SUSY) breaking terms receive comparable anomaly-mediation and moduli-mediation contributions leading to the phenomenon of mirage unification. The simplest MM SUSY breaking models which are consistent with the measured Higgs mass and sparticle mass constraints are strongly disfavored by fine-tuning considerations. However, while MM makes robust predictions for gaugino masses, the scalar sector is quite sensitive to specific mechanisms for moduli stabilization and potential uplifting. We suggest here a broader setup of generalized mirage mediation (GMM), where heretofore discrete parameters are allowed as continuous to better parametrize these other schemes. We find that natural SUSY spectra consistent with both the measured value of mh as well as LHC lower bounds on superpartner masses are then possible. We explicitly show that models generated from natural GMM may be beyond the reach of even high-luminosity LHC searches. In such a case, the proposed International Linear e+e- Collider will be required for natural SUSY discovery via higgsino pair production reactions. We also outline prospects for detection of higgsino-like WIMPs from natural GMM.

  3. 顶体反应进程对公猪精液体外受精最佳精卵比的影响%Effect of acrosome reaction progress on optimal sperm/oocyte ratios in IVF of boars

    Institute of Scientific and Technical Information of China (English)

    周华龙; 孙铭菊; 刘世超; 郭佳; 何文腾; 胡魁; 尹智; 刘忠华; 崔卫国

    2015-01-01

    精液质量参数相似公猪获得相同体外受精(in vitro fertilization,IVF)效果时所需精卵比不同的原因.常规方法鉴定公猪精液质量参数,以不同精卵比进行体外受精并确定不同公猪精液体外受精时的最佳精卵比,分别检测了各公猪精子结合透明带能力、获能及顶体反应状况.3头试验用公猪(A、B和C)精液在精子密度、活率、活力和畸形精子率上无显著差异(P>0.05),17℃保存3d内精子的活率在三者间无差异(P>0.05).3头公猪精液在IVF中达到最佳受精效率时所需的精卵比分别为500∶1、1 000∶1和200∶1.精子结合透明带能力和获能进程检测显示三者无显著差异(P>0.05),但顶体反应进程检测显示三者间具有显著差异(P<0.05).顶体反应进程差异是导致相似精液质量精液之间在IVF中最佳精卵比不同的主要原因.

  4. Axion Mediation

    CERN Document Server

    Baryakhtar, Masha; March-Russell, John

    2013-01-01

    We explore the possibility that supersymmetry breaking is mediated to the Standard Model sector through the interactions of a generalized axion multiplet that gains a F-term expectation value. Using an effective field theory framework we enumerate the most general possible set of axion couplings and compute the Standard Model sector soft-supersymmetry-breaking terms. Unusual, non-minimal spectra, such as those of both natural and split supersymmetry are easily implemented. We discuss example models and low-energy spectra, as well as implications of the particularly minimal case of mediation via the QCD axion multiplet. We argue that if the Peccei-Quinn solution to the strong-CP problem is realized in string theory then such axion-mediation is generic, while in a field theory model it is a natural possibility in both DFSZ- and KSVZ-like regimes. Axion mediation can parametrically dominate gravity-mediation and is also cosmologically beneficial as the constraints arising from axino and gravitino overproduction ...

  5. Mechanisms of severe transfusion reactions.

    Science.gov (United States)

    Kopko, P M; Holland, P V

    2001-06-01

    Serious adverse effects of transfusion may be immunologically or non-immunologically mediated. Currently, bacterial contamination of blood products, particularly platelets, is one of the most significant causes of transfusion-related morbidity and mortality. Septic transfusion reactions can present with clinical symptoms similar to immune-mediated hemolytic transfusion reactions and transfusion-related acute lung injury. Extremely high fever and/or gastrointestinal symptoms, in a transfusion recipient, may be indicative of sepsis. The diagnosis is based upon culturing the same organism from both the patient and the transfused blood component. Numerous organisms have been implicated as the cause of septic transfusion reactions. Due to different storage conditions, gram negative organisms are more often isolated from red blood cell components; gram positive organisms are more often isolated from platelets. Prevention of septic transfusion reactions is primarily dependent on an adequate donor history and meticulous preparation of the donor phlebotomy site. Visual inspection of blood components prior to transfusion is also vital to preventing these reactions. Several methods of detection of bacterial contamination and inactivation of pathogens are currently under active investigation.

  6. Mediatized Parenthood

    DEFF Research Database (Denmark)

    Sonne Damkjær, Maja

    2017-01-01

    to parenthood? The dissertation explores this question on the basis of a synchronous study within an overall mediatization perspective. The first part of the dissertation focuses on a conceptualization of the relationship between digital media and parenting as well as an exploration of theoretical perspectives...... and methods that make it possible to study the interactions between the two. Concretely, the dissertation builds on a number of key studies within audience research, which have contributed knowledge about the media’s role in the family and the home. This is done by including three approaches to mediatization......) a family-oriented, b) a peer-oriented, c) an oppositional, and d) non-use. Secondary contribution: Based on qualitative audience research and mediatization theory, the dissertation contributes a conceptualization of the relationship between media and parenthood. This is carried out in a study design...

  7. Mediating Business

    DEFF Research Database (Denmark)

    "Mediating Business" is a study of the expansion of business journalism. Building on evidence from Denmark, Finland, Norway and Sweden, "Mediating Business" is a comparative and multidisciplinary study of one of the major transformations of the mass media and the realm of business - nationally...... and globally. The book explores the history of key innovations and innovators in the business press. It analyzes changes in the discourse of business journalism associated with the growth in business news and the development of new ways of framing business issues and events. Finally, it examines...... the organizational implications of the increased media visibility of business and, in particular, the development of corporate governance and media relations....

  8. Mediatized play

    DEFF Research Database (Denmark)

    Johansen, Stine Liv

    Children’s play must nowadays be understood as a mediatized field in society and culture. Media – understood in a very broad sense - holds severe explanatory power in describing and understanding the practice of play, since play happens both with, through and inspired by media of different sorts....... In this presentation the case of ‘playing soccer’ will be outlined through its different mediated manifestations, including soccer games and programs on TV, computer games, magazines, books, YouTube videos and soccer trading cards....

  9. Synthesis of 4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide ring systems on sugar templates via carbanion-mediated sulfonamide intramolecular cyclization reactions (CSIC protocols) of glyco-alpha-sulfonamidonitriles.

    Science.gov (United States)

    Domínguez, Laura; van Nhien, Albert Nguyen; Tomassi, Cyrille; Len, Christophe; Postel, Denis; Marco-Contelles, José

    2004-02-01

    The carbanion-mediated sulfonate intramolecular cyclizations (CSIC protocols) of glyco-alpha-sulfonamidonitriles derived from readily available monosaccharides have been extensively investigated using potassium carbonate, cesium carbonate, n-BuLi, and LDA as bases. As a result, a series of enantiomerically pure spiro(4-amino-5-H-2,3-dihydroisothiazole-1,1-dioxide) derivatives have been prepared efficiently and isolated in good yield. The synthesis of these new bicyclic systems is key to accessing a novel range of aza analogues of TSAO nucleosides (ATSAOs).

  10. TEMPO/viologen electrochemical heterojunction for diffusion-controlled redox mediation: a highly rectifying bilayer-sandwiched device based on cross-reaction at the interface between dissimilar redox polymers.

    Science.gov (United States)

    Tokue, Hiroshi; Oyaizu, Kenichi; Sukegawa, Takashi; Nishide, Hiroyuki

    2014-03-26

    A couple of totally reversible redox-active molecules, which are different in redox potentials, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and viologen (V(2+)), were employed to give rise to a rectified redox conduction effect. Single-layer and bilayer devices were fabricated using polymers containing these sites as pendant groups per repeating unit. The devices were obtained by sandwiching the redox polymer layer(s) with indium tin oxide (ITO)/glass and Pt foil electrodes. Electrochemical measurements of the single-layer device composed of polynorbornene-bearing TEMPO (PTNB) exhibited a diffusion-limited current-voltage response based on the TEMPO(+)/TEMPO exchange reaction, which was almost equivalent to a redox gradient through the PTNB layer depending upon the thickness. The bilayer device gave rise to the current rectification because of the thermodynamically favored cross-reaction between TEMPO(+) and V(+) at the polymer/polymer interface. A current-voltage response obtained for the bilayer device demonstrated a two-step diffusion-limited current behavior as a result of the concurrent V(2+)/V(+) and V(+)/V(0) exchange reactions according to the voltage and suggested that the charge transport process through the device was most likely to be rate-determined by a redox gradient in the polymer layer. Current collection experiments revealed a charge transport balance throughout the device, as a result of the electrochemical stability and robustness of the polymers in both redox states.

  11. Signal enhancement for gene detection based on a redox reaction of [Fe(CN)(6)](4-) mediated by ferrocene at the terminal of a peptide nucleic acid as a probe with hybridization-amenable conformational flexibility.

    Science.gov (United States)

    Aoki, Hiroshi; Tao, Hiroaki

    2008-07-01

    Electrochemically enhanced DNA detection was demonstrated by utilizing the couple of a synthesized ferrocene-terminated peptide nucleic acid (PNA) with a cysteine anchor and a sacrificial electron donor [Fe(CN)(6)](4-). DNA detection sensors were prepared by modifying a gold electrode surface with a mixed monolayer of the probe PNA and 11-hydroxy-1-undecanethiol (11-HUT), protecting [Fe(CN)(6)](4-) from any unexpected redox reaction. Before hybridization, the terminal ferrocene moiety of the probe was subject to a redox reaction due to the flexible probe structure and, in the presence of [Fe(CN)(6)](4-), the observed current was amplified based on regeneration of the ferrocene moiety. Hybridization decreased the redox current of the ferrocene. This occurred because hybridization rigidified the probe structure: the ferrocene moiety was then removed from the electrode surface, and the redox reaction of [Fe(CN)(6)](4-) was again prevented. The change in the anodic current before and after hybridization was enhanced 1.75-fold by using the electron donor [Fe(CN)(6)](4-). Sequence-specific detection of the complementary target DNA was also demonstrated.

  12. Discovery of human posterior head 20 (hPH20) and homo sapiens sperm acrosome associated 1 (hSPACA1) immunocontraceptive epitopes and their effects on fertility in male and female mice.

    Science.gov (United States)

    Chen, Xuemei; Liu, Xiaodong; Ren, Xiuhua; Li, Xuewu; Wang, Li; Zang, Weidong

    2016-03-01

    The key goals of immunocontraception research are to obtain full contraceptive effects using vaccines administered to both males and females. Current research concerning human anti-sperm contraceptive vaccines is focused on delineating infertility-related epitopes to avoid autoimmune disease. We constructed phage-display peptide libraries to select epitope peptides derived from human posterior head 20 (hPH20) and homo sapiens sperm acrosome associated 1 (hSPACA1) using sera collected from infertile women harbouring anti-sperm antibodies. Following five rounds of selection, positive colonies were reconfirmed for reactivity with the immunoinfertile sera. We biopanned and analysed the chemical properties of four epitope peptides, named P82, Sa6, Sa37 and Sa76. Synthetic peptides were made and coupled to either bovine serum albumin (BSA) or ovalbumin. We used the BSA-conjugated peptides to immunise BALB/c mice and examined the effects on fertility in female and male mice. The synthetic peptides generated a sperm-specific antibody response in female and male mice that caused a contraceptive state. The immunocontraceptive effect was reversible and, with the disappearance of peptide-specific antibodies, there was complete restoration of fertility. Vaccinations using P82, Sa6 and Sa76 peptides resulted in no apparent side effects. Thus, it is efficient and practical to identify epitope peptide candidates by phage display. These peptides may find clinical application in the specific diagnosis and treatment of male and female infertility and contraceptive vaccine development.

  13. 叔丁醇钾促进的形成碳—碳及碳—杂键的偶联反应的研究进展%Recent Progress in the Research of the t-BuOK-Mediated Coupling Reactions to Form Carbon-Carbon and Carbon-Heteroatom Bonds

    Institute of Scientific and Technical Information of China (English)

    王良贵; 严国兵; 张鑫燕

    2012-01-01

    Potassium tert-butoxide has wide application as a strong base and weak nucleophilie in organic chemistry. In this paper, the newest development of the t-BuOK-mediated coupling reactions is reviewed. The main focuses are the formation of carbon-carbon, carbon-ziitrogen and carbon-oxygen bonds. The formation mechanisms of these bonds are discussed in details.%叔丁醇钾由于其碱性强而亲核性相对较弱在有机合成中得到广泛应用.综述了近年来叔丁醇钾促进的交叉偶联反应的研究进展,主要包括碳-碳、碳-氮及碳-氧键的形成及其反应机理的探讨.

  14. Rh(I)-catalyzed transformation of propargyl vinyl ethers into (E,Z)-dienals: stereoelectronic role of trans effect in a metal-mediated pericyclic process and a shift from homogeneous to heterogeneous catalysis during a one-pot reaction.

    Science.gov (United States)

    Vidhani, Dinesh V; Krafft, Marie E; Alabugin, Igor V

    2014-01-01

    The combination of experiments and computations reveals unusual features of stereoselective Rh(I)-catalyzed transformation of propargyl vinyl ethers into (E,Z)-dienals. The first step, the conversion of propargyl vinyl ethers into allene aldehydes, proceeds under homogeneous conditions via a "cyclization-mediated" mechanism initiated by Rh(I) coordination at the alkyne. This path agrees well with the small experimental effects of substituents on the carbinol carbon. The key feature revealed by the computational study is the stereoelectronic effect of the ligand arrangement at the catalytic center. The rearrangement barriers significantly decrease due to the greater transfer of electron density from the catalytic metal center to the CO ligand oriented trans to the alkyne. This effect increases electrophilicity of the metal and lowers the calculated barriers by 9.0 kcal/mol. Subsequent evolution of the catalyst leads to the in situ formation of Rh(I) nanoclusters that catalyze stereoselective tautomerization. The intermediacy of heterogeneous catalysis by nanoclusters was confirmed by mercury poisoning, temperature-dependent sigmoidal kinetic curves, and dynamic light scattering. The combination of experiments and computations suggests that the initially formed allene-aldehyde product assists in the transformation of a homogeneous catalyst (or "a cocktail of catalysts") into nanoclusters, which in turn catalyze and control the stereochemistry of subsequent transformations.

  15. Type I hypersensitivity reaction as a complication of lepa

    OpenAIRE

    Janthli, Deepa Manjunath; Chaturvedi, Ashutosh; Somashekar, Shruthi; Lohith, B. A.

    2015-01-01

    Adverse drug reaction is defined as response to a drug which is noxious and unintended, and which occurs at doses normally used in man for the prophylaxis, diagnosis or therapy of disease, or for the modification of physiological functions. Type I hypersensitivity reaction is known as anaphylactic reaction which is due to immediate immunoglobulin E-mediated reaction. It is characterized by symptoms such as fever nausea, back pain, angiodema, rash, flushing, etc. Lepa generally refers to the a...

  16. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  17. Snake antivenoms: adverse reactions and production technology

    Directory of Open Access Journals (Sweden)

    VM Morais

    2009-01-01

    Full Text Available Antivenoms have been widely used for more than a century for treating snakebites and other accidents with poisonous animals. Despite their efficacy, the use of heterologous antivenoms involves the possibility of adverse reactions due to activation of the immune system. In this paper, alternatives for antivenom production already in use were evaluated in light of their ability to minimize the occurrence of adverse reactions. These effects were classified according to their molecular mechanism as: anaphylactic reactions mediated by IgE, anaphylactoid reactions caused by complement system activation, and pyrogenic reactions produced mainly by the presence of endotoxins in the final product. In the future, antivenoms may be replaced by humanized antibodies, specific neutralizing compounds or vaccination. Meanwhile, improvements in antivenom quality will be focused on the obtainment of a more purified and specific product in compliance with good manufacturing practices and at an affordable cost.

  18. Semen collection and polymerase chain reaction-based sex determination of black-headed and straw-necked ibis.

    Science.gov (United States)

    Kaneko, K; Uematsu, E; Takahashi, Y; Tong, B; Takino, S; Wajiki, Y; Kimura, T; Yamashiro, H; Kaneko, Y; Iwaisaki, H; Sugiyama, T; Yamada, T; Yamagishi, S

    2013-12-01

    This study aimed to develop a polymerase chain reaction (PCR)-based sexing and effective semen collection methods for black-headed and straw-necked ibis species. However, most birds are not sexually dimorphic, that is, the sexes appear similar. Therefore, the gender should be determined before semen collection. DNA was extracted from the blood samples of 11 black-headed and 4 straw-necked ibis. The sex was determined after PCR amplification of the EE0.6 region of W-chromosome. The PCR products were separated using gel electrophoresis. A single band indicated the presence of the EE0.6 region and that the individual was a female, while no band indicated that the individual was a male. Further, the single bands from seven specimens were amplified. Semen collection was performed by massage or a combination of massage with electro-ejaculation and was attempted during all four seasons. The semen was successfully collected in March from male straw-necked ibis using the massage method. Limited motility, viability and concentration of straw-necked ibis sperm were observed. The sperm length was 180 μm and that of the nucleus was 30 μm with acrosome located at the tip of the nucleus. Thus, the PCR-based sexing proved to be an accurate molecular sexing method for black-headed and straw-necked ibis. Furthermore, we successfully collected semen and observed the stained sperm nucleus and acrosome of the straw-necked ibis sperm. We propose that the use of this PCR methodology can be applied as a routine method for sex determination and semen collection in ibis species for future ecological research. However, considering our limited success, further studies on semen collection method are required.

  19. Mechanisms in adverse reactions to food. The ear

    DEFF Research Database (Denmark)

    Høst, A

    1995-01-01

    Otitis media with effusion is rarely caused by allergy to food. Allergic inflammation in the nasal mucosa, mainly due to IgE-mediated reactions to foods, may cause eustachian tube dysfunction and subsequent otitis media with effusion. Inflammatory mediators from the nasal mucosa transported via t...

  20. Air-Driven Potassium Iodide-Mediated Oxidative Photocyclization of Stilbene Derivatives.

    Science.gov (United States)

    Matsushima, Tomoya; Kobayashi, Sayaka; Watanabe, Soichiro

    2016-09-02

    A new method has been developed for the potassium iodide-mediated oxidative photocyclization of stilbene derivatives. Compared with conventional iodine-mediated oxidative photocyclization reactions, this new method requires shorter reaction times and affords cyclized products in yields of 45-97%. This reaction proceeds with a catalytic amount of potassium iodide and works in an air-driven manner without the addition of an external scavenger. The radical-mediated oxidative photocyclization of stilbene derivatives using TEMPO was also investigated.

  1. Copper-mediated electrophilic imination of alkenylzirconocenes with O-benzoyl ketoximes and aldoximes.

    Science.gov (United States)

    Liu, Hailan; Yan, Xiaoyu; Chen, Chao; Liu, Qingbin; Xi, Chanjuan

    2013-06-18

    Copper-mediated electrophilic imination of alkenylzirconocenes generated in situ from alkynes and zirconocenes is accomplished under mild reaction conditions. The reaction can be used to prepare various 2-azadienes.

  2. Hypersensitivity reaction to pine nuts (pinon nuts--pignolia).

    Science.gov (United States)

    Fine, A J

    1987-09-01

    This report describes two patients with allergic reactions due to the ingestion of pine nuts. Skin testing to the aqueous allergen revealed immediate positive prick test reactions suggesting an IgE-mediated response. No reported cases have been found previously in a review of the medical literature.

  3. Immunological aspects of nonimmediate reactions to beta-lactam antibiotics.

    Science.gov (United States)

    Rodilla, Esther Morena; González, Ignacio Dávila; Yges, Elena Laffond; Bellido, Francisco Javier Múñoz; Bara, María Teresa Gracia; Toledano, Félix Lorente

    2010-09-01

    beta-lactam antibiotics are the agents most frequently implied in immune drug adverse reactions. These can be classified as immediate or nonimmediate according to the time interval between the last drug administration and their onset. Mechanisms of immediate IgE-mediated reactions are widely studied and are therefore better understood. Nonimmediate reactions include a broad number of clinical entities like mild maculopapular exanthemas, the most common, and other less frequent but more severe reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, acute exanthematic pustulosis or cytopenias. These nonimmediate reactions are mainly mediated by T cells but the precise underlying mechanisms are not well elucidated. This fact complicates the allergological evaluation of patients with this type of reaction and available tests have demonstrated poor sensitivity and specificity.

  4. First Magnesium-mediated Carbonyl Benzylation in Water

    Institute of Scientific and Technical Information of China (English)

    DENG,Wei(邓维); TAN,Xiang-Hui(谭翔辉); LIU,Lei(刘磊); GUO,Qing-Xiang(郭庆祥)

    2004-01-01

    Catalyzed by AgNO3, Mg was found for the first time to be able to mediate the coupling reaction between aromatic aldehydes and benzyl bromide or chloride in water. The yields were slightly higher than the recent results for Mg-mediated allylation despite the fact that aqueous benzylation is intrinsically much harder than allylation. It was also found that the coupling reaction was chemoselective for aromatic aldehydes over aliphatic aldehydes, and chemoselective for aromatic aldehydes over aromatic ketones.

  5. Carbonyl-Olefin Exchange Reaction and Related Chemistry

    Science.gov (United States)

    Jossifov, Christo; Kalinova, Radostina

    A new carbon—carbon double bond forming reaction (carbonyl olefin exchange reaction) mediated by transition metal catalytic systems has been discovered. The catalytic systems used (transition metal halides or oxohalides alone or in combination with Lewis acids) are active only in the case when the two reacting groups are in one molecules and are conjugated. In addition these systems accelerate other reactions which run simultaneously with the carbonyl olefin metathesis rendering a detailed investigation of the process very complicated.

  6. Mechanisms in adverse reactions to food. The nose

    DEFF Research Database (Denmark)

    Høst, A

    1995-01-01

    Rhinitis is a common symptom in food allergic patients, but rhinitis is rarely the only symptom. Rhinitis due to adverse reactions to preservatives and colorants is very rare. In anaphylactic systemic reactions to foods the rhinitis symptoms are caused by inflammatory mediators transported...... by the circulation. In non-anaphylactic reactions, the nasal inflammation and symptoms are probably induced by interaction with food allergens transported to the nasal mucosa via the blood circulation....

  7. Plasmon-mediated electrochemical reactions: the influence of nanoparticle structure

    Energy Technology Data Exchange (ETDEWEB)

    Willets, Katherine A. [Univ. of Texas, Austin, TX (United States)

    2015-09-25

    This document describes research performed at the University of Texas at Austin under award DE-SC0010307. This award has been transferred to Temple University upon the move of the PI from her original institution to a new institution.

  8. Anapylactoid Reactions Mediated by Autoantibodies to Cholesterol in Miniature Pigs

    Science.gov (United States)

    1989-11-01

    eicosanoid secretion. leucopenia , and 20 thrombocytopenia. Hemolytic C titers, and leucocyte and 0 platelet counts were measured before and after...although reduced) and a concom- itant decrease in CO, and the leucopenia and thrombo- vation and this was associated with an anaphylactoid cytopenia

  9. Characterization of NAADP-mediated calcium signaling in human spermatozoa

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Tusie, A.A. [Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos (Mexico); Vasudevan, S.R.; Churchill, G.C. [Department of Pharmacology, University of Oxford, Oxford OX1 3QT, England (United Kingdom); Nishigaki, T. [Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos (Mexico); Treviño, C.L., E-mail: ctrevino@ibt.unam.mx [Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos (Mexico)

    2014-01-10

    Highlights: •Human sperm cells synthesize NAADP. •NAADP-AM mediates [Ca{sup 2+}]{sub i} increases in human sperm in the absence of [Ca{sup 2+}]{sub o}. •Human sperm have two acidic compartments located in the head and midpiece. -- Abstract: Ca{sup 2+} signaling in spermatozoa plays a crucial role during processes such as capacitation and release of the acrosome, but the underlying molecular mechanisms still remain unclear. Nicotinic acid adenine dinucleotide phosphate (NAADP) is a potent Ca{sup 2+}-releasing second messenger in a variety of cellular processes. The presence of a NAADP synthesizing enzyme in sea urchin sperm has been previously reported, suggesting a possible role of NAADP in sperm Ca{sup 2+} signaling. In this work we used in vitro enzyme assays to show the presence of a novel NAADP synthesizing enzyme in human sperm, and to characterize its sensitivity to Ca{sup 2+} and pH. Ca{sup 2+} fluorescence imaging studies demonstrated that the permeable form of NAADP (NAADP-AM) induces intracellular [Ca{sup 2+}] increases in human sperm even in the absence of extracellular Ca{sup 2+}. Using LysoTracker®, a fluorescent probe that selectively accumulates in acidic compartments, we identified two such stores in human sperm cells. Their acidic nature was further confirmed by the reduction in staining intensity observed upon inhibition of the endo-lysosomal proton pump with Bafilomycin, or after lysosomal bursting with glycyl-L-phenylalanine-2-naphthylamide. The selective fluorescent NAADP analog, Ned-19, stained the same subcellular regions as LysoTracker®, suggesting that these stores are the targets of NAADP action.

  10. Palladium-mediated intracellular chemistry

    Science.gov (United States)

    Yusop, Rahimi M.; Unciti-Broceta, Asier; Johansson, Emma M. V.; Sánchez-Martín, Rosario M.; Bradley, Mark

    2011-03-01

    Many important intracellular biochemical reactions are modulated by transition metals, typically in the form of metalloproteins. The ability to carry out selective transformations inside a cell would allow researchers to manipulate or interrogate innumerable biological processes. Here, we show that palladium nanoparticles trapped within polystyrene microspheres can enter cells and mediate a variety of Pd0-catalysed reactions, such as allylcarbamate cleavage and Suzuki-Miyaura cross-coupling. The work provides the basis for the customization of heterogeneous unnatural catalysts as tools to carry out artificial chemistries within cells. Such in cellulo synthesis has potential for a plethora of applications ranging from cellular labelling to synthesis of modulators or inhibitors of cell function.

  11. Double Pion Production Reactions

    CERN Document Server

    Oset, E; Cano, F; Hernández, E; Kamalov, S S; Nacher, J C; Tejedor, J A G

    1999-01-01

    We report on reactions producing two pions induced by real and virtual photons or nucleons. The role of different resonances in these reactions is emphasized. Novel results on coherent two pion photoproduction in nuclei are also reported.

  12. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  13. Microscale Thermite Reactions.

    Science.gov (United States)

    Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana

    1998-01-01

    Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

  14. Anaphylactic reactions to ingested carmine (E120).

    Science.gov (United States)

    Wüthrich, B; Kägi, M K; Stücker, W

    1997-11-01

    We report five cases of anaphylactic reaction to carmine (cochineal, E120) after patients drank an alcoholic beverage. By means of positive skin prick tests (SPT) and positive RAST to carmine. IgE-mediated sensitization could be established. One nonatopic patient showed also a great amount of serum IgE antibodies to the carmine acid-albumin conjugate. Due to its widespread use in the food and cosmetic industry, carmine should be tested in the allergy work-up in case of allergic reactions after a drink or a meal.

  15. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  16. Reaction systems with precipitation

    Directory of Open Access Journals (Sweden)

    Marek Rogalski

    2015-04-01

    Full Text Available This article proposes expanding Reaction Systems of Ehrenfeucht and Rozenberg by incorporating precipitation reactions into it. This improves the computing power of Reaction Systems by allowing us to implement a stack. This addition enables us to implement a Deterministic Pushdown Automaton.

  17. Kiss-induced severe anaphylactic reactions

    Directory of Open Access Journals (Sweden)

    Atanasković-Marković Marina

    2010-01-01

    Full Text Available Introduction. Ingestion is the principal route for food allergens to trigger allergic reaction in atopic persons. However, in some highly sensitive patients severe symptoms may develop upon skin contact and by inhalation. The clinical spectrum ranges from mild facial urticaria and angioedema to life-threatening anaphylactic reactions. Outline of Cases. We describe cases of severe anaphylactic reactions by skin contact, induced by kissing in five children with prior history of severe anaphylaxis caused by food ingestion. These cases were found to have the medical history of IgE mediated food allergy, a very high total and specific serum IgE level and very strong family history of allergy. Conclusion. The presence of tiny particles of food on the kisser's lips was sufficient to trigger an anaphylactic reaction in sensitized children with prior history of severe allergic reaction caused by ingestion of food. Allergic reaction provoked with food allergens by skin contact can be a risk factor for generalized reactions. Therefore, extreme care has to be taken in avoiding kissing allergic children after eating foods to which they are highly allergic. Considering that kissing can be a cause of severe danger for the food allergic patient, such persons should inform their partners about the risk factor for causing their food hypersensitivity.

  18. A Novel Mechanism for Halogenated Quinone- Mediated and Metal-Independent Organic Fenton-Like Reaction%不依赖于过渡金属离子的卤代醌介导的新型有机类Fenton反应机理

    Institute of Scientific and Technical Information of China (English)

    朱本占; 任福荣; 夏海英; 邵杰

    2012-01-01

    卤代醌是许多卤芳香持久有机污染物的致癌代谢产物和饮用水消毒副产物.羟基自由基(OH)被公认为生物系统中最具活性的活性氧物种,能导致生物体内DNA等生物大分子的氧化损伤.目前,最被广泛接受的OH产生机理是过渡金属离子催化的Fenton反应.综合采用电子自旋共振二级自旋捕获和其他分析方法,发现四氯苯醌和其它卤代醌皆可通过不依赖于过渡金属离子的途径,显著促进氢过氧化物(H2O2或有机氢过氧化物)的分解而产生OH或烷氧自由基,并首次检测到一种新型的、以碳为中心的醌自由基.基于以上研究,提出一类不依赖于过渡金属离子的卤代醌介导的新型有机类Fenton反应机理.%Halogenated quinones are a class of carcinogenic metabolites of many halogenated persistent organic pollutants and new chlorination disinfection byproducts in drinking water. The hydroxyl radical ("OH) has been considered to be one of the most reactive oxygen species produced in biological systems. It has been shown that 'OH can cause oxidative damage to DNA and other macromolecuies. One of the most widely accepted mechanisms for OH production is through the transition metal-catalyzed Fenton reaction. Through the complementary application of electron spin resonance (ESR) secondary spin-trapping and other analytical methods, we found that tetrachloro-1,4-benzoquinone (TCBQ) and other halogenated quinones could markedly enhance the decomposition of hydroperoxides (H2O2 and organic hydroperoxides) and formation of "OH and alkoxyl radicals independent of transition metal ions. A novel carbon-centered quinone ketoxy radical was also detected and identified for the first time. Based on these data, we proposed a novel mechanism for metal-independent and halogenated quinone-mediated organic Fenton-like reaction.

  19. Silver and gold-catalyzed multicomponent reactions

    Directory of Open Access Journals (Sweden)

    Giorgio Abbiati

    2014-02-01

    Full Text Available Silver and gold salts and complexes mainly act as soft and carbophilic Lewis acids even if their use as σ-activators has been rarely reported. Recently, transformations involving Au(I/Au(III-redox catalytic systems have been reported in the literature. In this review we highlight all these aspects of silver and gold-mediated processes and their application in multicomponent reactions.

  20. mediation: R Package for Causal Mediation Analysis

    Directory of Open Access Journals (Sweden)

    Dustin Tingley

    2014-09-01

    Full Text Available In this paper, we describe the R package mediation for conducting causal mediation analysis in applied empirical research. In many scientific disciplines, the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. Causal mediation analysis is frequently used to assess potential causal mechanisms. The mediation package implements a comprehensive suite of statistical tools for conducting such an analysis. The package is organized into two distinct approaches. Using the model-based approach, researchers can estimate causal mediation effects and conduct sensitivity analysis under the standard research design. Furthermore, the design-based approach provides several analysis tools that are applicable under different experimental designs. This approach requires weaker assumptions than the model-based approach. We also implement a statistical method for dealing with multiple (causally dependent mediators, which are often encountered in practice. Finally, the package also offers a methodology for assessing causal mediation in the presence of treatment noncompliance, a common problem in randomized trials.

  1. Bayesian Mediation Analysis

    Science.gov (United States)

    Yuan, Ying; MacKinnon, David P.

    2009-01-01

    In this article, we propose Bayesian analysis of mediation effects. Compared with conventional frequentist mediation analysis, the Bayesian approach has several advantages. First, it allows researchers to incorporate prior information into the mediation analysis, thus potentially improving the efficiency of estimates. Second, under the Bayesian…

  2. Mediation as Signal

    NARCIS (Netherlands)

    Holler, M.J.; Lindner, I.

    2004-01-01

    This paper analyzes mediation as a signal. Starting from a stylized case, a game theoretical model of one-sided incomplete information, taken from Cho and Kreps (1987), is applied to discuss strategic effects of mediation. It turns out that to reject mediation can be interpreted as a ”negative signa

  3. Noncanonical Reactions of Flavoenzymes

    Directory of Open Access Journals (Sweden)

    Pablo Sobrado

    2012-11-01

    Full Text Available Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a “molecular scaffold” in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.

  4. CONVENTIONAL RENAL CELL CARCINOMA WITH GRANULOMATOUS REACTION

    Directory of Open Access Journals (Sweden)

    Srinivas

    2014-09-01

    Full Text Available : Granulomatous inflammation is a distinctive pattern of chronic inflammatory reaction characterized by microscopic aggregation of activated macrophages which often develop epithelioid appearance and multinucleate giant cells. Granulomas are encountered in limited number of infectious and some non-infectious conditions. Granulomas have been described within the stroma of malignancies like carcinomas of the breast and colon, seminoma and Hodgkin’s lymphoma, where they represent T-cell-mediated reaction of the tumor stroma to antigens expressed by the tumor. Granulomatous reaction in association with renal cell carcinoma (RCC is uncommon, with only few published reports in the literature. We describe a case of conventional (clear cell RCC associated with epithelioid cell granulomas within the tumor parenchyma.

  5. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.

    2005-01-01

    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl tereph

  6. Metal-mullite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Labs., Albuquerque, NM (United States); Tomsia, A.P. [Pask Research and Engineering, Berkeley, CA (United States)

    1993-11-01

    Mullite was reacted with pure Al and with Ti or Zr dissolved in Ag-Cu eutectic alloys at 1100 C in Ar. Analysis of the Ti and Zr-containing specimens showed reaction zones with compositions of Ti{sub 50}Cu{sub 3O}O{sub 20} and ZrO{sub 2}, respectively. The Al-mullite specimen showed much more extensive penetration into the ceramic and a more diffuse reaction zone than the other two systems. Al{sub 2}O{sub 3} and Si were the main reaction products for Al-mullite reaction.

  7. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  8. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  9. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  10. Reactions to Attitudinal Deviancy.

    Science.gov (United States)

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  11. Chemical burn or reaction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000059.htm Chemical burn or reaction To use the sharing features on this page, please enable JavaScript. Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ...

  12. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.

    2005-01-01

    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  13. Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Whitesides, R.; Domin, D.; Salomon-Ferrer, R.; Lester Jr., W.A.; Frenklach, M.

    2007-12-01

    Reaction pathways are presented for hydrogen-mediated isomerization of a five and six member carbon ring complex on the zigzag edge of a graphene layer. A new reaction sequence that reverses orientation of the ring complex, or 'flips' it, was identified. Competition between the flip reaction and 'ring separation' was examined. Ring separation is the reverse of the five and six member ring complex formation reaction, previously reported as 'ring collision'. The elementary steps of the pathways were analyzed using density-functional theory (DFT). Rate coefficients were obtained by solution of the energy master equation and classical transition state theory utilizing the DFT energies, frequencies, and geometries. The results indicate that the flip reaction pathway dominates the separation reaction and should be competitive with other pathways important to the graphene zigzag edge growth in high temperature environments.

  14. Involvement of Histamine and RhoA/ROCK in Penicillin Immediate Hypersensitivity Reactions

    OpenAIRE

    Jiayin Han; Yan Yi; Chunying Li; Yushi Zhang; Lianmei Wang; Yong Zhao; Chen Pan; Aihua Liang

    2016-01-01

    The mechanism of penicillin immediate hypersensitivity reactions has not been completely elucidated. These reactions are generally considered to be mediated by IgE, but penicillin-specific IgE could not be detected in most cases. This study demonstrated that penicillin was able to cause vascular hyperpermeability in a mouse model mimicking clinical symptoms of penicillin immediate hypersensitivity reactions. The first exposure to penicillin also induced immediate edema and exudative reactions...

  15. Recent advances in N-heterocyclic carbene (NHC-catalysed benzoin reactions

    Directory of Open Access Journals (Sweden)

    Rajeev S. Menon

    2016-03-01

    Full Text Available N-Heterocyclic carbenes (NHCs have emerged as a powerful class of organocatalysts that mediate a variety of organic transformations. The Benzoin reaction constitutes one of the earliest known carbon–carbon bond-forming reactions catalysed by NHCs. The rapid growth of NHC catalysis in general has resulted in the development of a variety of benzoin and benzoin-type reactions. An overview of such NHC-catalysed benzoin reactions is presented.

  16. Technology-Use Mediation

    DEFF Research Database (Denmark)

    Bansler, Jørgen P.; Havn, Erling C.

    2003-01-01

    This study analyzes how a group of ‘mediators’ in a large, multinational company adapted a computer-mediated communication technology (a ‘virtual workspace’) to the organizational context (and vice versa) by modifying features of the technology, providing ongoing support for users, and promoting...... of technology-use mediation is more complex and indeterminate than earlier literature suggests. In particular, we want to draw attention to the fact that advanced computer-mediated communication technologies are equivocal and that technology-use mediation consequently requires ongoing sensemaking (Weick 1995)....... appropriate conventions of use. Our findings corroborate earlier research on technology-use mediation, which suggests that such mediators can exert considerable influence on how a particular technology will be established and used in an organization. However, this study also indicates that the process...

  17. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  18. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  19. An Expedient Regio- and Diastereoselective Synthesis of Hybrid Frameworks with Embedded Spiro[9,10]dihydroanthracene [9,3′]-pyrrolidine and Spiro[oxindole-3,2′-pyrrolidine] Motifs via an Ionic Liquid-Mediated Multicomponent Reaction

    Directory of Open Access Journals (Sweden)

    Natarajan Arumugam

    2015-09-01

    Full Text Available A series of hitherto unreported anthracene-embedded dispirooxindoles has been synthesized via a one-pot three-component 1,3-dipolar cycloaddition reaction of an azomethine ylide, generated in situ from the reaction of isatin and sarcosine to 10-benzylideneanthracen-9(10H-one as a dipolarophile in 1-butyl-3-methylimidazolium bromide([bmim]Br, an ionic liquid. This reaction proceeded regio- and diastereoselectively, in good to excellent yields.

  20. Chemisorption And Precipitation Reactions

    Science.gov (United States)

    The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

  1. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  2. Translated chemical reaction networks.

    Science.gov (United States)

    Johnston, Matthew D

    2014-05-01

    Many biochemical and industrial applications involve complicated networks of simultaneously occurring chemical reactions. Under the assumption of mass action kinetics, the dynamics of these chemical reaction networks are governed by systems of polynomial ordinary differential equations. The steady states of these mass action systems have been analyzed via a variety of techniques, including stoichiometric network analysis, deficiency theory, and algebraic techniques (e.g., Gröbner bases). In this paper, we present a novel method for characterizing the steady states of mass action systems. Our method explicitly links a network's capacity to permit a particular class of steady states, called toric steady states, to topological properties of a generalized network called a translated chemical reaction network. These networks share their reaction vectors with their source network but are permitted to have different complex stoichiometries and different network topologies. We apply the results to examples drawn from the biochemical literature.

  3. Oral Hypersensitivity Reactions

    Science.gov (United States)

    ... food, food additives, drugs, oral hygiene products, and dental materials. Q: Are there any specific foods that are ... dental treatment trigger a hypersensitivity reaction? A: Some dental materials used by the dentist can cause a hypersensitivity ...

  4. Response reactions: equilibrium coupling.

    Science.gov (United States)

    Hoffmann, Eufrozina A; Nagypal, Istvan

    2006-06-01

    It is pointed out and illustrated in the present paper that if a homogeneous multiple equilibrium system containing k components and q species is composed of the reactants actually taken and their reactions contain only k + 1 species, then we have a unique representation with (q - k) stoichiometrically independent reactions (SIRs). We define these as coupling reactions. All the other possible combinations with k + 1 species are the coupled reactions that are in equilibrium when the (q - k) SIRs are in equilibrium. The response of the equilibrium state for perturbation is determined by the coupling and coupled equilibria. Depending on the circumstances and the actual thermodynamic data, the effect of coupled equilibria may overtake the effect of the coupling ones, leading to phenomena that are in apparent contradiction with Le Chatelier's principle.

  5. Ofloxacin induced hypersensitivity reaction

    Directory of Open Access Journals (Sweden)

    Hari Babu Ramineni

    2015-01-01

    Full Text Available Ofloxacin is a commonly used antimicrobial agent to combat various infections. The adverse profile of quinolones includes gastrointestinal symptoms, which are the most frequent, neuropsychiatric symptoms, hematologic abnormalities are less common. We report a rare case of ofloxacin induced hypersensitivity reaction in a 57 year old female patient with complaints of rashes over the axilla, upper limb and back, abdomen, thorax associated with exfoliation of skin all over the axilla associated with severe itching. Based on history and clinical examination patient was diagnosed as ofloxacin induced hypersensitivity reaction and was successfully treated with antihistamines and corticosteroids. Pharmacovigilance should be a part of patient care in order to reduce occurrence of adverse drug reaction and also encourage practitioners in reporting so as to gather more and more data regarding adverse drug reactions. [Int J Res Med Sci 2015; 3(1.000: 349-351

  6. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T;

    2005-01-01

    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... match, the right substance being suspected, but investigations showed an additional allergen or several substances, including the right substance being suspected. CONCLUSIONS: An informed guess is not a reliable way of determining the cause of a supposed allergic reaction during anaesthesia and may put...

  7. Carbon mediated catalysis:A review on oxidative dehydrogenation

    Institute of Scientific and Technical Information of China (English)

    De Chen; Anders Holmen; Zhijun Sui; Xinggui Zhou

    2014-01-01

    Carbon mediated catalysis has gained an increasing attention in both areas of nanocatalysis and nanomaterials. The progress in carbon nanomaterials provides many new opportunities to manip-ulate the types and properties of active sites of catalysts through manipulating structures, function-alities and properties of carbon surfaces. The present review focuses on progresses in carbon medi-ated oxidative dehydrogenation reactions of ethylbenzene, propane, and butane. The state-of-the-art of the developments of carbon mediated catalysis is discussed in terms of fundamental studies on adsorption of oxygen and hydrocarbons, reaction mechanism as well as effects of carbon nano-material structures and surface functional groups on the catalytic performance. We highlight the importance and challenges in tuning of the electron density of carbon and oxygen on carbon surfac-es for improving selectivity in oxidative dehydrogenation reactions.

  8. Oxygen evolution reaction catalysis

    Science.gov (United States)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  9. Meson production in + reactions

    Indian Academy of Sciences (India)

    H Machner; M Betigeri; J Bojowald; A Budzanowski; A Chatterjee; J Ernst; L Freindl; D Frekers; W Garske; K Grewer; A Hamacher; J Ilieva; L Jarczyk; K Kilian; S Kliczewski; W Klimala; D Kolev; T Kutsarova; J Lieb; H Machner; A Magiera; H Nann; L Pentchev; H S Plendl; D Protić; B Razen; P Von Rossen; B J Roy; R Siudak; J Smyrski; R V Srikantiah; A Strzałkowski; R Tsenov; K Zwoll

    2001-08-01

    Total and differential cross sections for the reactions $p+d → 3He + 0 with = ; and + → 3H + + were measured with the GEM detector at COSY for beam momenta between threshold and the maximum of the corresponding baryon resonance. For both reactions a strong forward–backward asymmetry was found. The data were compared with model calculations. The aspect of isospin symmetry breaking is studied.

  10. Accurate Reaction Enthalpies and Sources of Error in DFT Thermochemistry for Aldol, Mannich, and α-Aminoxylation Reactions

    Science.gov (United States)

    Wheeler, Steven E.; Moran, Antonio; Pieniazek, Susan N.; Houk, K. N.

    2009-08-01

    Enthalpies for bond-forming reactions that are subject to organocatalysis have been predicted using the high-accuracy CBS-QB3 model chemistry and six DFT functionals. Reaction enthalpies were decomposed into contributions from changes in bonding and other intramolecular effects via the hierarchy of homodesmotic reactions. The order of the reaction exothermicities (aldol < Mannich ≈ α-aminoxylation) arises primarily from changes in formal bond types mediated by contributions from secondary intramolecular interactions. In each of these reaction types, methyl substitution at the β- and γ-positions stabilizes the products relative to the unsubstituted case. The performance of six DFT functionals (B3LYP, B3PW91, B1B95, MPW1PW91, PBE1PBE, and M06-2X), MP2, and SCS-MP2 has been assessed for the prediction of these reaction enthalpies. Even though the PBE1PBE and M06-2X functionals perform well for the aldol and Mannich reactions, errors roughly double when these functionals are applied to the α-aminoxylation reactions. B3PW91 and B1B95, which offer modest accuracy for the aldol and Mannich reactions, yield reliable predictions for the two α-aminoxylation reactions. The excellent performance of the M06-2X and PBE1PBE functionals for aldol and Mannich reactions stems from the cancellation of sizable errors arising from inadequate descriptions of the underlying bond transformations and intramolecular interactions. SCS-MP2/cc-pVTZ performs most consistently across these three classes of reactions, although the reaction exothermicities are systematically underestimated by 1-3 kcal mol-1. Conventional MP2, when paired with the cc-pVTZ basis set, performs somewhat better than SCS-MP2 for some of these reactions, particularly the α-aminoxylations. Finally, the merits of benchmarking DFT functionals for the set of simple chemically meaningful transformations underlying all bond-forming reactions are discussed.

  11. Recent advances in copper-catalyzed asymmetric coupling reactions

    Directory of Open Access Journals (Sweden)

    Fengtao Zhou

    2015-12-01

    Full Text Available Copper-catalyzed (or -mediated asymmetric coupling reactions have received significant attention over the past few years. Especially the coupling reactions of aryl or alkyl halides with nucleophiles became a very powerful tool for the formation of C–C, C–N, C–O and other carbon–heteroatom bonds as well as for the construction of heteroatom-containing ring systems. This review summarizes the recent progress in copper-catalyzed asymmetric coupling reactions for the formation of C–C and carbon–heteroatom bonds.

  12. Dynamic public service mediation

    NARCIS (Netherlands)

    Hofman, W.; Staalduinen, M. van

    2010-01-01

    This paper presents an approach to dynamic public service mediation. It is based on a conceptual model and the use of search and ranking algorithms. The conceptual model is based on Abstract State Machine theory. Requirements for dynamic service mediation were derived from a real-world case. The con

  13. Teaching Mediated Public Relations.

    Science.gov (United States)

    Kent, Michael L.

    2001-01-01

    Discusses approaches to teaching a mediated public relations course, emphasizing the World Wide Web. Outlines five course objectives, assignments and activities, evaluation, texts, and lecture topics. Argues that students mastering these course objectives will understand ethical issues relating to media use, using mediated technology in public…

  14. Ruimte voor mediation

    NARCIS (Netherlands)

    Combrink-Kuiters, L.; Niemeijer, E.; Voert, M. ter

    2003-01-01

    Dit onderzoek is samen met ADR en mediation Rechterlijke macht gepubliceerd. Het doel was enerzijds na te gaan of, en onder welke condities, mediation in de Nederlandse context een effectief en efficiënt alternatief is voor de gerechtelijke geschillenbeslechting. Anderzijds inzicht te verwerven in d

  15. Music, Radio, and Mediatization

    DEFF Research Database (Denmark)

    Krogh, Mads; Michelsen, Morten

    2016-01-01

    Mediatization has become a key concept for understanding the relations between media and other cultural and social fields. Contributing to the discussions related to the concept of mediatization, this article discusses how practices of radio and music(al life) influence each other. We follow Deacon......’s and Stanyer’s advice to supplement the concept of mediatization with ‘a series of additional concepts at lower levels of abstraction’ and suggest, in this respect, the notion of heterogeneous milieus of music– radio. Hereby, we turn away from the all-encompassing perspectives related to the concept...... of mediatization where media as such seem to be ascribed agency. Instead, we consider historical accounts of music–radio in order to address the complex non- linearity of concrete processes of mediatization as they take place in the multiple meetings between a decentred notion of radio and musical life....

  16. The Schizosaccharomyces pombe Mediator

    DEFF Research Database (Denmark)

    Venturi, Michela

    In the past several years great attention has been dedicated to the characterization of the Mediator complex in a different range of model organisms. Mediator is a conserved co-activator complex involved in transcriptional regulation and it conveys signals from regulatory transcription factors......+ is a nonessential gene, while deletion of med11+ resulted in unviable cells. These results are in line with those obtained in S. cerevisiae. Isolation of S. pombe Mediator by the tandem affinity purification method and Co-IP experiments lead to the conclusion that Med9 and Med11 might not belong to the Mediator...... complex, but our results did not exclude it completely either. Our attempts to demonstrate the presence of these two subunits in the Mediator complex remain inconclusive primarily due to the lack of proper expression of the tagged versions of the proteins. However, we have paved a way to further...

  17. Chemical reactions directed Peptide self-assembly.

    Science.gov (United States)

    Rasale, Dnyaneshwar B; Das, Apurba K

    2015-05-13

    Fabrication of self-assembled nanostructures is one of the important aspects in nanoscience and nanotechnology. The study of self-assembled soft materials remains an area of interest due to their potential applications in biomedicine. The versatile properties of soft materials can be tuned using a bottom up approach of small molecules. Peptide based self-assembly has significant impact in biology because of its unique features such as biocompatibility, straight peptide chain and the presence of different side chain functionality. These unique features explore peptides in various self-assembly process. In this review, we briefly introduce chemical reaction-mediated peptide self-assembly. Herein, we have emphasised enzymes, native chemical ligation and photochemical reactions in the exploration of peptide self-assembly.

  18. Radical Reactions and Its Synthetic Application

    Institute of Scientific and Technical Information of China (English)

    Takeaki Naito

    2005-01-01

    @@ 1Introduction Strategies involving radical reactions have become preeminent tools in organic synthesis. Free radical-mediated cyclization has developed as a powerful method for preparing various types of cyclic compounds via carbon-carbon bond-forming processes. In order to develop effective and convenient methods for the synthesis of biologically active cyclic amines, we have focused our efforts on radical reactions using aldehydes, ketones,and C-C multiple bonds as a radical precursor and/or an oxime ether, hydrazone, and nitrone as a radical acceptor. In this lecture, I would like to talk on radical addition-cyclization of oxime ether and its application to the synthesis of martinellines.

  19. Immediate reaction to clarithromycin.

    Science.gov (United States)

    Gangemi, S; Ricciardi, L; Fedele, R; Isola, S; Purello-D'Ambrosio, F

    2001-01-01

    We present the case of bronchospastic reaction to clarithromycin had during a drug challenge test. Personal allergic history was negative for respiratory allergies and positive for adverse drug reactions to general and regional anesthesia and to ceftriaxone. After the administration of 1/4 of therapeutic dose of clarithromycin the patient showed dyspnea, cough and bronchospasm in all the lung fields. The positivity of the test was confirmed by the negativity to the administration of placebo. The quickness and the clinical characteristic of the adverse reaction suggest a pathogenic mechanism of immediate-type hypersensitivity. On reviewing the literature we have found no reports of bronchospastic reaction to clarithromycin. Macrolides are a class of antibiotics mainly used in the last years in place of beta-lactams because of a broad spectrum of action and a low allergic power. In fact, there are few reports on allergic reactions to these molecules. Clarithromycin is one of the latest macrolides, characterised by the presence of a 14-carbon-atom lactone ring as erythromycin, active on a wide spectrum of pathogens.

  20. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  1. Nanoparticle Reactions on Chip

    Science.gov (United States)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  2. Inflammatory reaction in chondroblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Yamamura, Sigeki [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sato, Keiji [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Sugiura, Hideshi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan); Iwata, Hisashi [Dept. of Orthopedic Surgery, Nagoya Univ. School of Medicine (Japan)

    1996-05-01

    The objective of this study was to evaluate the inflammatory reaction accompanying chondroblastoma and to define the value of the finding in clinical practice. We reviewed the clinical, radiographic, and magnetic resonance (MR) findings in six patients with histologically proven chondroblastoma. In all cases, MR imaging showered marrow and soft tissue edema. In four of six cases, periosteal reaction related to intra-osseous edema was more clearly demonstrated on MR imaging than on radiographs. Follow-up MR studies after surgery were available in three patients and all showed disappearance of inflammatory responses such as marrow and soft tissue edema, and reactive synovitis. We propose that these inflammatory reactions of chondroblastomas are inportant signs for detecting residual tumor in recurrences after surgery, as well as for making a precise diagnosis. The MR changes may also be valuable in demonstrating eradication of the tumor. (orig./MG)

  3. Adverse reactions to cosmetics

    Directory of Open Access Journals (Sweden)

    Dogra A

    2003-03-01

    Full Text Available Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly shaving creams caused more reaction as compared to other cosmetics. Overall incidence of contact allergic dermatitis seen was 3.3% with patients own cosmetics. Patch testing was also done with the basic ingredients and showed positive results in few cases where casual link could be established. It is recommended that labeling of the cosmetics should be done to help the dermatologists and the patients to identify the causative allergen in cosmetic preparation.

  4. The role of Zn-alpha2 glycoprotein in sperm motility is mediated by changes in cyclic AMP.

    Science.gov (United States)

    Qu, Fei; Ying, Xiaoqian; Guo, Wei; Guo, Qiangsu; Chen, Guowu; Liu, Yue; Ding, Zhide

    2007-10-01

    Sperm motility is essential for male reproduction or natural fertilization. The cyclic AMP (cAMP)/cAMP-dependent protein kinase A (PKA) signaling pathway is generally recognized as one of the significant signaling pathways in the regulation of mammalian spermatozoan motility. Since Zn-alpha2-glycoprotein (ZAG) activity in mammalian adipose tissue is mediated via the beta(3)-adrenoreceptor, with upregulation of the cAMP pathway, we hypothesize that ZAG may play the same role in sperm motility regulation, a new factor of regulation of sperm motility. Therefore, the gene encoding human ZAG was cloned and polyclonal antibodies were generated, and then laser scanning confocal microscopy and flow cytometry were employed to identify this protein in human spermatozoa. The results showed that ZAG protein was mostly localized on the pre-equatorial region covering the acrosome, neck, and middle piece of the flagellum of spermatozoa. Furthermore, using computer-assisted sperm analysis, we found that anti-human ZAG antibodies could significantly reduce the motility of human swim-up spermatozoa after 90- or 120-min incubation (Pspermatozoa and may be involved in the regulation of sperm motility via the cAMP/PKA signaling pathway.

  5. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)

    2007-07-01

    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  6. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

      When, in a competitive sphere, people are selected on the basis of qualifications only, their chances of acquiring positions of advantage may seem to depend entirely upon their abilities, not discriminatory bias. However, if reaction qualifications - i.e. characteristics which contribute...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...

  7. [Mediation in health].

    Science.gov (United States)

    Decastello, Alice

    2008-02-10

    The author presents mediation as an alternative dispute resolution method. Mediation is a process where the parties are ready to settle their dispute out of court, by way of negotiation and with the involvement of an independent third person as mediator. In the mediation process the mediator shall not decide the dispute, nor examine the default or give legal advice or express his/her opinion - the mediator's duty is to help the parties bring their positions closer and come to a settlement agreement within a short time (120 days). The author gives a summary of the applications of the Hungarian Act on Mediation in Public Health and draws conclusions from the practical experience since entry into force of the legislation and illustrates the advantages of mediation over the court procedure (which may drag on for years). The primary advantages of mediation are that both the mediators and the parties are bound by the obligation of secrecy, the procedure is cheaper than the court proceedings, and the parties can "save their faces" because in mediation the winner-winner formula asserts itself - against lawsuits where the winner-loser positions are confronted. The author also analyses the specific data and information available so far. As for the future, the legislation needs to be amended at several points. It is particularly expedient to regulate the legal relationship between the insurance companies and the health service providers because the liability insurance may not cover the damages the courts adjudicate. And so some of the service providers may go bankrupt as the difference in excess of the upper limit of coverage - it might as well be up to HUF 5 million per case - shall be paid from own budget, to the charge of the upkeep costs. It is also required to review and amend the regulations on expert activities, just as it is inevitable to make data supply compulsory - otherwise it will be impossible to monitor the number of mediation procedures in health. At present

  8. General resonance mediation

    Energy Technology Data Exchange (ETDEWEB)

    McGarrie, Moritz

    2012-07-15

    We extend the framework of general gauge mediation to cases where the mediating fields have a nontrivial spectral function, as might arise from strong dynamics. We demonstrate through examples that this setup describes a broad class of possible models of gauge mediated supersymmetry breaking. A main emphasis is to give general formulas for cross sections for {sigma}(visible {yields} hidden) in these resonance models. We will also give formulas for soft masses, A-terms and demonstrate the framework with a holographic setup.

  9. The mechanism of the modified Ullmann reaction.

    Science.gov (United States)

    Sperotto, Elena; van Klink, Gerard P M; van Koten, Gerard; de Vries, Johannes G

    2010-11-21

    The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since these catalysts are homogeneous, it has opened up the possibility to investigate the mechanism of these modified Ullmann reactions. Most authors agree that Cu(I) is the true catalyst even though Cu(0) and Cu(II) catalysts have also shown to be active. It should be noted however that Cu(I) is capable of reversible disproportionation into Cu(0) and Cu(II). In the first step, the nucleophile displaces the halide in the LnCu(I)X complex forming LnCu(I)ZR (Z = O, NR′, S). Quite a number of mechanisms have been proposed for the actual reaction of this complex with the aryl halide: 1. Oxidative addition of ArX forming a Cu(III) intermediate followed by reductive elimination; 2. Sigma bond metathesis; in this mechanism copper remains in the Cu(II) oxidation state; 3. Single electron transfer (SET) in which a radical anion of the aryl halide is formed (Cu(I)/Cu(II)); 4. Iodine atom transfer (IAT) to give the aryl radical (Cu(I)/Cu(II)); 5. π-complexation of the aryl halide with the Cu(I) complex, which is thought to enable the nucleophilic substitution reaction. Initially, the radical type mechanisms 3 and 4 where discounted based on the fact that radical clock-type experiments with ortho-allyl aryl halides failed to give the cyclised products. However, a recent DFT study by Houk, Buchwald and co-workers shows that the modified Ullmann reaction between aryl iodide and amines or primary alcohols proceeds either via an SET or an IAT mechanism. Van Koten has shown that stalled aminations can be rejuvenated by the addition of Cu(0), which serves to reduce the formed Cu(II) to Cu

  10. The Gewald multicomponent reaction

    NARCIS (Netherlands)

    Huang, Yijun; Doemling, Alexander

    2011-01-01

    The Gewald reaction of sulfur, cyanoacetic acid derivatives, and oxo-component (G-3CR) yielding highly substituted 2-aminothiophene derivatives has seen diverse applications in combinatorial and medicinal chemistry. Its products are of great use in pharmaceutical industry mainly as small molecular w

  11. Chemical Reactions at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Michael Henderson and Nancy Ryan Gray

    2010-04-14

    Chemical reactions at surfaces underlie some of the most important processes of today, including catalysis, energy conversion, microelectronics, human health and the environment. Understanding surface chemical reactions at a fundamental level is at the core of the field of surface science. The Gordon Research Conference on Chemical Reactions at Surfaces is one of the premiere meetings in the field. The program this year will cover a broad range of topics, including heterogeneous catalysis and surface chemistry, surfaces in environmental chemistry and energy conversion, reactions at the liquid-solid and liquid-gas interface, electronic materials growth and surface modification, biological interfaces, and electrons and photons at surfaces. An exciting program is planned, with contributions from outstanding speakers and discussion leaders from the international scientific community. The conference provides a dynamic environment with ample time for discussion and interaction. Attendees are encouraged to present posters; the poster sessions are historically well attended and stimulate additional discussions. The conference provides an excellent opportunity for junior researchers (e.g. graduate students or postdocs) to present their work and interact with established leaders in the field.

  12. Reactions of Negative Ions

    Science.gov (United States)

    1984-07-17

    2 + H2 SO 4 + HS04 (HNO 3 ) 2 + HNO 3 1.1 0.6 * defined as 1 The most important results from an atmospheric viewpoint are the reactions of H SO with NO...constant HS04 >4.5 bracketing 22 0 C1 , 1.95 * 0.25 bracketlng 32 -4 __.. . .___,_=____,,_______... . . . -- . . . . One particularly interesting aspect of

  13. Cluster knockout reactions

    Indian Academy of Sciences (India)

    Arun K Jain; B N Joshi

    2014-04-01

    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  14. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    2001-01-01

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive re

  15. Reaction Formulation: A Bibliography.

    Science.gov (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    Reaction formation was studied by Sigmund Freud. This defense mechanism may be related to repression, substitution, reversal, and compensation (or over-compensation). Alfred Adler considered compensation a basic process in his individual psychology. Anna Freud discussed some defense mechanisms, and Bibring, Dwyer, Huntington, and Valenstein…

  16. Reaction product imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  17. Enantioselective Vinylogous Organocascade Reactions.

    Science.gov (United States)

    Hepburn, Hamish B; Dell'Amico, Luca; Melchiorre, Paolo

    2016-08-01

    Cascade reactions are powerful tools for rapidly assembling complex molecular architectures from readily available starting materials in a single synthetic operation. Their marriage with asymmetric organocatalysis has led to the development of novel techniques, which are now recognized as reliable strategies for the one-pot enantioselective synthesis of stereochemically dense molecules. In recent years, even more complex synthetic challenges have been addressed by applying the principle of vinylogy to the realm of organocascade catalysis. The key to the success of vinylogous organocascade reactions is the unique ability of the chiral organocatalyst to transfer reactivity to a distal position without losing control on the stereo-determining events. This approach has greatly expanded the synthetic horizons of the field by providing the possibility of forging multiple stereocenters in remote positions from the catalyst's point of action with high selectivity, while simultaneously constructing multiple new bonds. This article critically describes the developments achieved in the field of enantioselective vinylogous organocascade reactions, charting the ideas, the conceptual advances, and the milestone reactions that have been essential for reaching highly practical levels of synthetic efficiency.

  18. EXERCISE AND REACTION TIMES

    Directory of Open Access Journals (Sweden)

    Varun

    2015-03-01

    Full Text Available OBJECTIVES: Physical exercise provides multiple benefits to an individual. It is known that exercising regularly can prevent coronary heart disease, hypertension and obesity and improve flexibility. The effect of exercise on visual reaction time needs to be studied, a s the existing data on the benefit of aerobic exercise on psychomotor functions is insufficient. MATERIALS AND METHODS: Online Visual reaction time is measured before and after exercise. Subjects were instructed to run on the spot with a springy step in ex aggerated motion for 50 to 60 counts at 2 counts per second, maintaining a constant rhythm. RESULTS: We observed that reaction time was significantly lower after performance of exercise. Individuals reported improved mental alertness, feel good factor, bet ter mood and increase circulation. CONCLUSION: Improving reaction times in sports can help the athlete to optimize his performance in making decisions and increasing attention span for example getting off the starting blocks sooner or successfully making c ontact with the ball. In addition this study shows that use of physical exercise helps improve cognitive function. Exercise proves to be a cheap non pharmacological alternative to improve cognitive performance.

  19. Technology-Use Mediation

    DEFF Research Database (Denmark)

    Bansler, Jørgen P.; Havn, Erling C.

    2004-01-01

    Implementation of new computer-mediated communication (CMC) systems in organizations is a complex socio-technical endeavour, involving the mutual adaptation of technology and organization over time. Drawing on the analytic concept of sensemaking, this paper provides a theoretical perspective...... that deepens our understanding of how organizations appropriate new electronic communication media. The paper analyzes how a group of mediators in a large, multinational company adapted a new web-based CMC technology (a virtual workspace) to the local organizational context (and vice versa) by modifying...... features of the technology, providing ongoing support for users, and promoting appropriate conventions of use. We found that these mediators exerted considerable influence on how the technology was established and used in the organization. The mediators were not neutral facilitators of a well...

  20. Natural generalized mirage mediation

    CERN Document Server

    Baer, Howard; Serce, Hasan; Tata, Xerxes

    2016-01-01

    In the supersymmetric scenario known as mirage mediation (MM), the soft SUSY breaking terms receive comparable anomaly-mediation and moduli-mediation contributions leading to the phenomenon of mirage unification. The simplest MM SUSY breaking models which are consistent with the measured Higgs mass and sparticle mass constraints are strongly disfavoured by fine-tuning considerations. However, while MM makes robust predictions for gaugino masses, the scalar sector is quite sensitive to specific mechanisms for moduli stabilization and potential uplifting. We suggest here a broader setup of generalized mirage mediation (GMM), where heretofore discrete parameters are allowed as continuous to better parametrize these other schemes. We find that natural SUSY spectra consistent with both the measured value of m(h). as well as LHC lower bounds on superpartner masses are then possible. We explicitly show that models generated from natural GMM may be beyond the reach of even high-luminosity LHC searches. In such a case...

  1. DREDed Anomaly Mediation

    CERN Document Server

    Boyda, E; Pierce, A T; Boyda, Ed; Murayama, Hitoshi; Pierce, Aaron

    2002-01-01

    We offer a guide to dimensional reduction (DRED) in theories with anomaly mediated supersymmetry breaking. Evanescent operators proportional to epsilon arise in the bare Lagrangian when it is reduced from d=4 to d= (4-2 epsilon) dimensions. In the course of a detailed diagrammatic calculation, we show that inclusion of these operators is crucial. The evanescent operators conspire to drive the supersymmetry-breaking parameters along anomaly-mediation trajectories across heavy particle thresholds, guaranteeing the ultraviolet insensitivity.

  2. Anger and health in dementia caregivers: exploring the mediation effect of optimism.

    Science.gov (United States)

    López, J; Romero-Moreno, R; Márquez-González, M; Losada, A

    2015-04-01

    Although previous studies indicate a negative association between caregivers' anger and health, the potential mechanisms linking this relationship are not yet fully understood. The aim of this study was to explore the potential mediating role of optimism in the relationship between anger and caregivers' physical health. Dementia caregivers (n = 108) were interviewed and filled out instruments assessing their anger (reaction), optimism and health (vitality). A mediational model was tested to determine whether optimism partially mediated the relationship between anger and vitality. Angry reaction was negatively associated with optimism and vitality; optimism was positively associated with vitality. Finally, the relationship between angry reaction and vitality decreased when optimism was entered simultaneously. A non-parametric bootstrap approach confirmed that optimism significantly mediated some of the relationship between angry reaction and vitality. These findings suggest that low optimism may help explain the association between caregivers' anger and reduced sense of vitality. The results provide a specific target for intervention with caregivers.

  3. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions. The mo...

  4. Inorganic Reaction Mechanisms. Part I

    Science.gov (United States)

    Cooke, D. O.

    1976-01-01

    Provides a collection of data on the mechanistic aspects of inorganic chemical reactions. Wherever possible includes procedures for classroom demonstration or student project work. The material covered includes gas phase reactions, reactions in solution, mechanisms of electron transfer, the reaction between iron III and iodine, and hydrolysis. (GS)

  5. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (S{sub N}2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of S{sub N}2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing S{sub N}2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout S{sub N}2 mechanism involving CH{sub 3}-rotation. (orig.)

  6. Oral muscle relaxant may induce immediate allergic reactions.

    Science.gov (United States)

    Hur, Gyu-Young; Hwang, Eui Kyung; Moon, Jae-Young; Ye, Young-Min; Shim, Jae-Jeong; Park, Hae-Sim; Kang, Kyung-Ho

    2012-07-01

    Eperisone and afloqualone act by relaxing both skeletal and vascular smooth muscles to improve circulation and suppress pain reflex. These drugs are typically prescribed with non-steroidal anti-inflammatory drugs (NSAIDs) as painkillers. However, there have been no reports on serious adverse reactions to oral muscle relaxants; and this is the first report to describe three allergic reactions caused by eperisone and afloqualone. All three patients had histories of allergic reactions after oral intake of multiple painkillers, including oral muscle relaxants and NSAIDs, for chronic muscle pain. An open-label oral challenge test was performed with each drug to confirm which drugs caused the systemic reactions. All patients experienced the same reactions within one hour after oral intake of eperisone or afloqualone. The severity of these reactions ranged from laryngeal edema to hypotension. To confirm that the systemic reaction was caused by eperisone or afloqualone, skin prick testing and intradermal skin tests were performed with eperisone or afloqualone extract in vivo, and basophil activity tests were performed after stimulation with these drugs in vitro. In one patient with laryngeal edema, the intradermal test with afloqualone extract had a positive result, and CD63 expression levels on basophils increased in a dose-dependent manner by stimulation with afloqualone. We report three allergic reactions caused by oral muscle relaxants that might be mediated by non-immunoglobulin E-mediated responses. Since oral muscle relaxants such as eperisone and afloqualone are commonly prescribed for chronic muscle pain and can induce severe allergic reactions, we should prescribe them carefully.

  7. Urea hydrolysis and calcium carbonate reaction fronts

    Science.gov (United States)

    Fox, D. T.; Redden, G. D.; Henriksen, J.; Fujita, Y.; Guo, L.; Huang, H.

    2010-12-01

    The mobility of toxic or radioactive metal contaminants in subsurface environments can be reduced by the formation of mineral precipitates that form co-precipitates with the contaminants or that isolate them from the mobile fluid phase. An engineering challenge is to control the spatial distribution of precipitation reactions with respect to: 1) the location of a contaminant, and 2) where reactants are introduced into the subsurface. One strategy being explored for immobilizing contaminants, such as Sr-90, involves stimulating mineral precipitation by forming carbonate ions and hydroxide via the in situ, microbially mediated hydrolysis of urea. A series of column experiments have been conducted to explore how the construction or design of such an in situ reactant production strategy can affect the temporal and spatial distribution of calcium carbonate precipitation, and how the distribution is coupled to changes in permeability. The columns were constructed with silica gel as the porous media. An interval midway through the column contained an adsorbed urease enzyme in order to simulate a biologically active zone. A series of influent solutions were injected to characterize hydraulic properties of the column (e.g., bromide tracer), profiles of chemical conditions and reaction products as the enzyme catalyzes urea hydrolysis (e.g., pH, ammonia, urea), and changes that occur due to CaCO3 precipitation with the introduction of a calcium+urea solutions. In one experiment, hydraulic conductivity was reduced as precipitate accumulated in a layer within the column that had a higher fraction of fine grained silica gel. Subsequent reduction of permeability and flow (for a constant head condition) resulted in displacement of the hydrolysis and precipitation reaction profiles upstream. In another experiment, which lacked the physical heterogeneity (fine grained layer), the precipitation reaction did not result in loss of permeability or flow velocity and the reaction profile

  8. Non-IgE mediated mast cell activation

    NARCIS (Netherlands)

    Yu, Yingxin; Blokhuis, Bart R; Garssen, Johan; Redegeld, Frank A

    2016-01-01

    Mast cells are crucial effector cells in allergic reactions, where IgE is the best known mechanism to trigger their degranulation and release of a vast array of allergic mediators. However, IgE is not the only component to stimulate these cells to degranulate, while mast cell activation can also res

  9. Biochemistry and pathology of radical-mediated protein oxidation

    DEFF Research Database (Denmark)

    Dean, R T; Fu, S; Stocker, R

    1997-01-01

    Radical-mediated damage to proteins may be initiated by electron leakage, metal-ion-dependent reactions and autoxidation of lipids and sugars. The consequent protein oxidation is O2-dependent, and involves several propagating radicals, notably alkoxyl radicals. Its products include several catego...

  10. Non-IgE mediated mast cell activation

    NARCIS (Netherlands)

    Yu, Yingxin; Blokhuis, Bart R; Garssen, Johan; Redegeld, Frank A

    2015-01-01

    Mast cells are crucial effector cells in allergic reactions, where IgE is the best known mechanism to trigger their degranulation and release of a vast array of allergic mediators. However, IgE is not the only component to stimulate these cells to degranulate, while mast cell activation can also res

  11. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  12. Photooxidative reactions of psoralens

    Energy Technology Data Exchange (ETDEWEB)

    Potapenko, A.Ya.; Sukhorukov, V.L. (Vtoroj Moskovskij Gosudarstvennyj Meditsinskij Inst. (USSR))

    1984-08-31

    The mechanism and biological significance of photooxidative reactions of psoralens are reviewed. Skin-photosensitizing activities of bifunctional and monofunctional psoralens are compared. Antioxidants tocopherols and butilated hydroxytoluene inhibit photochemical reactions of psoralens responsible for induction of erythema. The same antioxidants do not inhibit PUVA-therapy of psriasis. Though psoralens can generate singlet oxygen under UVA-irradiation (315 - 400 nm), nevertheless singlet oxygen does not play a significant role in 8-methoxypsoralen (8-MOP) sensitized photooxidation of tocopherol or dihydroxyphenylalanine (DOPA). SH-compounds enhance the rate of 8-MOP sensitized photooxidation of DOPA by a factor of four, simultaneously the rate of oxidation of SH-groups is enhanced many fold in the presence of DOPA. Under UVA-irradiation in organic solvents psoralens are photooxidized. Dimeric photooxidized psoralens are easily destructed in water medium, their destruction induce oxidation of unsaturated lipids and DOPA.

  13. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

    1993-12-01

    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

  14. Acute coronary syndrome in diclofenac sodium-induced type I hypersensitivity reaction : Kounis syndrome

    OpenAIRE

    Gluvic, Zoran M.; Putnikovic, Biljana; Panic, Milos; Stojkovic, Aleksandra; Rasic-Milutinovic, Zorica; Jankovic-Gavrilovic, Jelena

    2007-01-01

    Drug-induced type I hypersensitivity reactions are frequent. Sometimes, acute coronary syndrome (ACS) can be registered in such patients, which may have a serious impact on the course and management of the allergic reaction. Because of potentially atypical ACS clinical presentations, the ECG is an obligatory diagnostic tool in any allergic reaction. Coronary artery spasm is the pathophysiological basis of ACS, triggered by the action of potent vasoactive mediators (histamine, neutral protease...

  15. Mediated Electron Transfer at Redox Active Monolayers. Part 4: Kinetics of Redox Enzymes Coupled With Electron Mediators

    Directory of Open Access Journals (Sweden)

    Michael E.G. Lyons

    2003-01-01

    Full Text Available A detailed kinetic analysis of the pertinent physical processes underlying the operation of enzyme electrodes immobilized within alkane thiol self assembled monolayers is developed. These electrodes utilize a soluble mediator, which partitions into the monolayer, regenerates the active catalytic form of the enzyme and is re-oxidized at the underlying support electrode surface giving rise to a current which reflects kinetic events at the enzyme surface. Both the enzyme/substrate and enzyme mediator kinetics have been quantified fully in terms of a ping-pong mechanism for the former and Michaelis-Menten kinetics for the latter. The effect of substrate and mediator diffusion in solution have also been specifically considered and the latter processes have been shown to result in a complex expression for the reaction flux. Four limiting kinetic cases have been enumerated and simple expressions for the reaction flux in each of these rate limiting situations have been developed. Kinetic case diagrams have been presented as an aid to mechanistic diagnosis. The complicating effects of diffusive loss of reduced mediator from the enzyme layer have also been examined and the relation between the observed flux corresponding to reduced mediator oxidation at the support electrode and the substrate reaction flux in the enzyme layer have been quantified in terms of an efficiency factor. Results extracted from recently published practical realizations of immobilized monolayer enzyme systems have been discussed in the context of the proposed model analysis.

  16. Metadata based mediator generation

    Energy Technology Data Exchange (ETDEWEB)

    Critchlow, T

    1998-03-01

    Mediators are a critical component of any data warehouse, particularly one utilizing partially materialized views; they transform data from its source format to the warehouse representation while resolving semantic and syntactic conflicts. The close relationship between mediators and databases, requires a mediator to be updated whenever an associated schema is modified. This maintenance may be a significant undertaking if a warehouse integrates several dynamic data sources. However, failure to quickly perform these updates significantly reduces the reliability of the warehouse because queries do not have access to the m current data. This may result in incorrect or misleading responses, and reduce user confidence in the warehouse. This paper describes a metadata framework, and associated software designed to automate a significant portion of the mediator generation task and thereby reduce the effort involved in adapting the schema changes. By allowing the DBA to concentrate on identifying the modifications at a high level, instead of reprogramming the mediator, turnaround time is reduced and warehouse reliability is improved.

  17. Fashion, Mediations & Method Assemblages

    DEFF Research Database (Denmark)

    Sommerlund, Julie; Jespersen, Astrid Pernille

    of handling multiple, fluid realities with multiple, fluid methods. Empirically, the paper works with mediation in fashion - that is efforts the active shaping of relations between producer and consumer through communication, marketing and PR. Fashion mediation is by no means simple, but organise complex...... Modern. New York, Harvester-Wheatsheaf. Law, J. (2004). After Method - mess in social science research. London and New York, Routledge......., it is an important ambition of this paper to go into a methodological discussion of how "that which effectively happens" can be approached. To this end, the paper will combine Hennion's term of the "mediator" with John Laws methodological term of "method assemblages". Method assemblages is a suggested as a way...

  18. The Strategic Mediator

    DEFF Research Database (Denmark)

    Rossignoli, Cecilia; Carugati, Andrea; Mola, Lapo

    2009-01-01

    The last 10 years have witnessed the emergence of electronic marketplaces as players that leverage new technologies to facilitate B2B internet-mediated collaborative business. Nowadays these players are augmenting their services from simple intermediation to include new inter-organizational relat......The last 10 years have witnessed the emergence of electronic marketplaces as players that leverage new technologies to facilitate B2B internet-mediated collaborative business. Nowadays these players are augmenting their services from simple intermediation to include new inter......-marketplace assumes the paradoxical role of strategic mediator: an agent who upholds and heightens the fences of the transactions instead of leveling them. The results have implication in shaping how we see the role of technology as strategic or commoditized....

  19. Urticaria and Allergy-Mediated Conditions.

    Science.gov (United States)

    Jafilan, Lena; James, Charis

    2015-12-01

    Urticaria is a common condition that involves pruritic, raised skin wheals. Although urticaria is a benign, self-limiting condition, it may cause frustration for patients, often because of its chronicity and its tendency to recur. It can also be a life-threatening allergic reaction. Diagnosis is made clinically. It affects 20% of the general population. The first-line treatment for nonremitting cases includes H-1anti-histamines. However, other therapies may be employed. Other allergy-mediated skin conditions include angioedema, contact dermatitis, and atopic dermatitis. Diagnosis is clinical, and management focuses on prevention, avoiding triggers, and treating the itching and inflammation that accompany these conditions.

  20. Reaction rate in an evanescent random walkers system

    CERN Document Server

    Ré, Miguel A

    2015-01-01

    Diffusion mediated reaction models are particularly ubiquitous in the description of physical, chemical or biological processes. The random walk schema is a useful tool for formulating these models. Recently, evanescent random walk models have received attention in order to include finite lifetime processes. For instance, activated chemical reactions, such as laser photolysis, exhibit a different asymptotic limit when compared with immortal walker models. A diffusion limited reaction model based on a one dimensional continuous time random walk on a lattice with evanescent walkers is presented here. The absorption probability density and the reaction rate are analytically calculated in the Laplace domain. A finite absorption rate is considered, a model usually referred to as imperfect trapping. Short and long time behaviors are analyzed.

  1. Ceruloplasmin decreases respiratory burst reaction during pregnancy.

    Science.gov (United States)

    Varfolomeeva, Elena Y; Semenova, Elena V; Sokolov, Alexey V; Aplin, Kirill D; Timofeeva, Kseniya E; Vasilyev, Vadim B; Filatov, Michael V

    2016-08-01

    Testing of pregnant women reveals weakening of neutrophil-mediated effector functions, such as reactive oxygen species generation. This study provides data confirming the phenomenon, gained through application of the flow cytometry technique. Key factors influencing neutrophil functional activity in blood plasma of pregnant women have not been detected so far. At the same time, concentration of ceruloplasmin - a copper-containing glycoprotein - is known to increase in blood significantly during pregnancy. We observed the negative correlation between ceruloplasmin concentration in blood plasma of pregnant women and the intensity of respiratory burst of neutrophils. Fractionation of plasma using gel-filtration revealed that ceruloplasmin-containing fraction demonstrated suppression of the respiratory burst reaction. Partial elimination of ceruloplasmin from the blood of pregnant women, performed with the help of specific antibodies and followed by immunoprecipitation, leads to an increased respiratory burst reaction. On the contrary, addition of ceruloplasmin to blood samples of healthy donors noticeably decreases the respiratory burst reaction. The results presented prove that change in ceruloplasmin level in plasma is necessary and sufficient for modulating the ability of neutrophils to produce reactive oxygen species during pregnancy.

  2. Well sealing via thermite reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, William Edward; Dunn, Sandra Dalvit

    2016-11-15

    A platform is formed in a well below a target plug zone by lowering a thermite reaction charge into the well and igniting it, whereby the products of the reaction are allowed to cool and expand to form a platform or support in the well. A main thermite reaction charge is placed above the platform and ignited to form a main sealing plug for the well. In some embodiments an upper plug is formed by igniting an upper thermite reaction charge above the main thermite reaction charge. The upper plug confines the products of ignition of the main thermite reaction charge.

  3. Overexpressing sperm surface beta 1,4-galactosyltransferase in transgenic mice affects multiple aspects of sperm-egg interactions

    OpenAIRE

    1994-01-01

    Sperm surface beta 1,4-galactosyltransferase (GalTase) mediates fertilization in mice by binding to specific O-linked oligosaccharide ligands on the egg coat glycoprotein ZP3. Before binding the egg, sperm GalTase is masked by epididymally derived glycosides that are shed from the sperm surface during capacitation. After binding the egg, sperm- bound oligosaccharides on ZP3 induce the acrosome reaction by receptor aggregation, presumably involving GalTase. In this study, we asked how increasi...

  4. Modelling toehold-mediated RNA strand displacement

    CERN Document Server

    Šulc, Petr; Romano, Flavio; Doye, Jonathan P K; Louis, Ard A

    2014-01-01

    We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate and that the displacement slows down with increasing temperature for longer toeholds.

  5. Models as Mediators

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    from laboratory studies, (Latour 1979; Lynch 1985; Sommerlund 2004 (2007); Sommerlund 2006) and is complemented by the attention paid to the "mediator" by Hennion (1989; 1997; 2005). The empirical focus will be on a central - but overlooked - actor of branding and advertising; the model. The model has...... solely been theorized within cultural studies (Craik 1994) as feminine spectacle, but has been neglected as mediator and actor. This paper will argue that models are co-producers of brands, and vice versa. Empirically, the paper will present interviews with models, model-scouts, agents, and advertisers...

  6. Mediated intimacy in families

    DEFF Research Database (Denmark)

    Stougaard, Malthe Kirkhoff

    2006-01-01

    Mediating intimacy between children and their parents is still limited investigated and at the same time, we find that, emerging technologies are about to change and affect the way we interact with each other. In this paper, we report from an empirical study where we investigated the social...... with other types of intimate relations such as strong-tie intimacy (couples cohabiting). However, we also identified several issues of intimacy unique to the special relation between children and their parents. These unique acts of intimacy propose challenges when designing technologies for mediated intimacy...

  7. Insect bite reactions

    Directory of Open Access Journals (Sweden)

    Sanjay Singh

    2013-01-01

    Full Text Available Insects are a class of living creatures within the arthropods. Insect bite reactions are commonly seen in clinical practice. The present review touches upon the medically important insects and their places in the classification, the sparse literature on the epidemiology of insect bites in India, and different variables influencing the susceptibility of an individual to insect bites. Clinical features of mosquito bites, hypersensitivity to mosquito bites Epstein-Barr virus NK (HMB-EBV-NK disease, eruptive pseudoangiomatosis, Skeeter syndrome, papular pruritic eruption of HIV/AIDS, and clinical features produced by bed bugs, Mexican chicken bugs, assassin bugs, kissing bugs, fleas, black flies, Blandford flies, louse flies, tsetse flies, midges, and thrips are discussed. Brief account is presented of the immunogenic components of mosquito and bed bug saliva. Papular urticaria is discussed including its epidemiology, the 5 stages of skin reaction, the SCRATCH principle as an aid in diagnosis, and the recent evidence supporting participation of types I, III, and IV hypersensitivity reactions in its causation is summarized. Recent developments in the treatment of pediculosis capitis including spinosad 0.9% suspension, benzyl alcohol 5% lotion, dimethicone 4% lotion, isopropyl myristate 50% rinse, and other suffocants are discussed within the context of evidence derived from randomized controlled trials and key findings of a recent systematic review. We also touch upon a non-chemical treatment of head lice and the ineffectiveness of egg-loosening products. Knockdown resistance (kdr as the genetic mechanism making the lice nerves insensitive to permethrin is discussed along with the surprising contrary clinical evidence from Europe about efficacy of permethrin in children with head lice carrying kdr-like gene. The review also presents a brief account of insects as vectors of diseases and ends with discussion of prevention of insect bites and some

  8. Multispecies pair annihilation reactions.

    Science.gov (United States)

    Deloubrière, Olivier; Hilhorst, Henk J; Täuber, Uwe C

    2002-12-16

    We consider diffusion-limited reactions A(i)+A(j)--> (12 and d> or =2, we argue that the asymptotic density decay for such mutual annihilation processes with equal rates and initial densities is the same as for single-species pair annihilation A+A-->. In d=1, however, particle segregation occurs for all q< infinity. The total density decays according to a q dependent power law, rho(t) approximately t(-alpha(q)). Within a simplified version of the model alpha(q)=(q-1)/2q can be determined exactly. Our findings are supported through Monte Carlo simulations.

  9. Organocatalytic Enantioselective Henry Reactions

    Directory of Open Access Journals (Sweden)

    Raquel P. Herrera

    2011-05-01

    Full Text Available A large number of interesting organocatalytic enantioselective protocols have been explored and successfully applied in the last decade. Among them, the Henry (nitroaldol reaction represents a powerful carbon-carbon bond-forming procedure for the preparation of valuable synthetic intermediates, such as enantioenriched nitro alcohols, which can be further transformed in a number of important nitrogen and oxygen-containing compounds. This area of research is still in expansion and a more complex version of this useful process has recently emerged, the domino Michael/Henry protocol, affording highly functionalized cycles with multiple stereogenic centers.

  10. Low Energy Nuclear Reactions?

    CERN Document Server

    CERN. Geneva; Faccini, R.

    2014-01-01

    After an introduction to the controversial problem of Low Energy Nuclear Reactions (LENR) catalyzed by neutrons on metallic hydride surfaces we present the results of an experiment, made in collaboration with ENEA Labs in Frascati, to search neutrons from plasma discharges in electrolytic cells. The negative outcome of our experiment goes in the direction of ruling out those theoretical models expecting LENR to occur in condensed matter systems under specific conditions. Our criticism on the theoretical foundations of such models will also be presented.

  11. Egg jelly of the newt, Cynops pyrrhogaster contains a factor essential for sperm binding to the vitelline envelope.

    Science.gov (United States)

    Hiyoshi, Wataru; Sasaki, Takayuki; Takayama-Watanabe, Eriko; Takai, Hiroyuki; Watanabe, Akihiko; Onitake, Kazuo

    2007-06-01

    The acrosome reaction of newt sperm is induced at the surface of egg jelly and the acrosome-reacted sperm acquire the ability to bind to the vitelline envelope. However, because the substance that induces the acrosome reaction has not been identified, the mechanism by which the acrosome-reacted sperm bind to the vitelline envelope remains unclear. We found here that a Dolichos biforus agglutinin (DBA) specifically mimicked the acrosome reaction immediately upon its addition in the presence of milimolar level Ca(2+). Fluorescein isothiocyanate-labeled DBA bound specifically to the acrosomal cap of the intact sperm in the presence of a Ca(2+)-chelating agent, EDTA, suggesting that binding of DBA to the native receptor for the egg jelly substance on the acrosomal region took the place of the egg jelly substance-induced acrosome reaction. In contrast, the sperm that had been acrosome reacted by DBA treatment did not bind to the vitelline envelope of the egg whose jelly layers were removed. Subsequent addition of jelly extract caused the sperm binding to vitelline envelope, indicating that the egg jelly of the newt contains substances that are involved in not only inducing the acrosome reaction but also binding to the vitelline envelope. This is the first demonstration of the involvement of egg jelly substance in the binding of acrosome-reacted sperm to the vitelline envelope.

  12. [The psychoimmunological network og panic disorders, agoraphobia and allergic reactions].

    Science.gov (United States)

    Schmidt-Traub, S

    1995-02-01

    While treating panic and agoraphobia patients with behaviour therapy, a high frequency of allergic reaction of the IgE-mediated type I was observed. Panic disorder, agoraphobia, allergic disorder, and vasomotor reactions are briefly discussed in the framework of psycho-endocrino-immunological research. A pilot study had shown a high correlation between panic disorder with and without agoraphobia and allergic reaction. A controlled study was then planned to test the hypothesized psychoimmunological relationship. 100 allergic patients, 79 panic/agoraphobic patients, and 66 controls underwent psychodiagnostic and allergic screening. 70% of the anxiety patients responded to test allergens with IgE-mediated type-I immediate reactions in comparison to 28% of the control persons. Another 15% of the panic patients reacted to nickle compound with type-IV delayed skin reactions (7% of the controls). Conversely, 10% of the allergic patients suffered from panic disorder (45% had experienced panic attacks) in contrast to 2% of the controls (24% of these reported panic attacks). The relative risk for allergic patients to develop panic disorder with and without agoraphobia is obviously five times as high as for controls. With this assumption of a psychoimmunological preparedness in mind, a behavioural medical diagnostic and therapeutic concept seems more adequate in coping both with panic/agoraphobia and allergic disorder.

  13. Non-IgE mediated mast cell activation.

    Science.gov (United States)

    Yu, Yingxin; Blokhuis, Bart R; Garssen, Johan; Redegeld, Frank A

    2016-05-05

    Mast cells are crucial effector cells in allergic reactions, where IgE is the best known mechanism to trigger their degranulation and release of a vast array of allergic mediators. However, IgE is not the only component to stimulate these cells to degranulate, while mast cell activation can also result in differential release of mediators. There is a plethora of stimuli, such as IgG, complement components, TLR ligands, neuropeptides, cytokines, chemokines and other inflammatory products, that can directly trigger mast cell degranulation, cause selective release of mediators, and stimulate proliferation, differentiation and/or migration. Moreover, some of these stimuli have a synergic effect on the IgE-mediated mast cell activation. Because of the ability to respond to a large repertoire of stimuli, mast cells may act as a versatile cell in various physiological and pathological conditions. In this review, we discuss current knowledge on non-IgE stimuli for (human) mast cells.

  14. Organic chemistry: Reactions triggered electrically

    Science.gov (United States)

    Xiang, Limin; Tao, N. J.

    2016-03-01

    Single-molecule experiments have revealed that chemical reactions can be controlled using electric fields -- and that the reaction rate is sensitive to both the direction and the strength of the applied field. See Letter p.88

  15. Click Reactions and Boronic Acids: Applications, Issues, and Potential Solutions

    Directory of Open Access Journals (Sweden)

    Chaofeng Dai

    2010-08-01

    Full Text Available Boronic acids have been widely used in a wide range of organic reactions, in the preparation of sensors for carbohydrates, and as potential pharmaceutical agents. With the growing importance of click reactions, inevitably they are also applied to the synthesis of compounds containing the boronic acid moiety. However, such applications have unique problems. Chief among them is the issue of copper-mediated boronic acid degradation in copper-assisted [2,3]-cycloadditions involving an alkyne and an azido compound as the starting materials. This review summarizes recent developments, analyzes potential issues, and discusses known as well as possible solutions.

  16. Teachers as mediators

    DEFF Research Database (Denmark)

    Dorf, Hans; Kelly, Peter; Hohmann, Ulrike

    2012-01-01

    Within the context of lower secondary English teaching in South West England, this study identifies in broad terms the competing goals between which English teachers mediate and the explicit and hidden tensions that result. To understand the interactions of competing goals, teachers’ goal...

  17. Mediatization and Government Communication

    DEFF Research Database (Denmark)

    Laursen, Bo; Valentini, Chiara

    2015-01-01

    in the light of mediatization and government communication theories. Without one pan-European public sphere, the European Parliament, like the other European Union (EU) institutions, competes with national actors for the news media’s attention in the EU’s twenty-eight national public spheres, where EU affairs...

  18. Expanding mediation theory

    NARCIS (Netherlands)

    Verbeek, P.P.C.C.

    2012-01-01

    In his article In Between Us, Yoni van den Eede expands existing theories of mediation into the realm of the social and the political, focusing on the notions of opacity and transparency. His approach is rich and promising, but two pitfalls should be avoided. First, his concept of ‘in-between’ runs

  19. Mediation and Automatization.

    Science.gov (United States)

    Hutchins, Edwin

    This paper discusses the relationship between the mediation of task performance by some structure that is not inherent in the task domain itself and the phenomenon of automatization, in which skilled performance becomes effortless or phenomenologically "automatic" after extensive practice. The use of a common simple explicit mediating…

  20. Thermally favourable gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Dalianis, Ioannis, E-mail: Ioannis.Dalianis@fuw.edu.p [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Hoza 69, Warsaw (Poland); Lalak, Zygmunt, E-mail: Zygmunt.Lalak@fuw.edu.p [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Hoza 69, Warsaw (Poland)

    2011-03-14

    We discuss the thermal evolution of the spurion and messenger fields of ordinary gauge mediation models taking into account the Standard Model degrees of freedom. It is shown that for thermalized messengers the metastable susy breaking vacuum becomes thermally selected provided that the susy breaking sector is sufficiently weakly coupled to messengers or to any other observable field.

  1. Theoretical Studies of Reaction Surfaces

    Science.gov (United States)

    2007-11-02

    Similar levels of agreement are being found in studies of water clusters12 , the Menshutkin reaction 13 (ion separation reaction ), a prototypical SN2 ...of both reactants and products. These analyses reveal that Bery pseudorotation occurs repeatedly during the side attack, whereas the SN2 reaction H...31 Aug 97 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS AASERT93 THEORETICAL STUDIES OF REACTION SURFACES F49620-93-1-0556 3484/XS 6. AUTHOR(S) 61103D DR

  2. Orbital Energy-Based Reaction Analysis of SN2 Reactions

    Directory of Open Access Journals (Sweden)

    Takao Tsuneda

    2016-07-01

    Full Text Available An orbital energy-based reaction analysis theory is presented as an extension of the orbital-based conceptual density functional theory. In the orbital energy-based theory, the orbitals contributing to reactions are interpreted to be valence orbitals giving the largest orbital energy variation from reactants to products. Reactions are taken to be electron transfer-driven when they provide small variations for the gaps between the contributing occupied and unoccupied orbital energies on the intrinsic reaction coordinates in the initial processes. The orbital energy-based theory is then applied to the calculations of several S N2 reactions. Using a reaction path search method, the Cl− + CH3I → ClCH3 + I− reaction, for which another reaction path called “roundabout path” is proposed, is found to have a precursor process similar to the roundabout path just before this SN2 reaction process. The orbital energy-based theory indicates that this precursor process is obviously driven by structural change, while the successor SN2 reaction proceeds through electron transfer between the contributing orbitals. Comparing the calculated results of the SN2 reactions in gas phase and in aqueous solution shows that the contributing orbitals significantly depend on solvent effects and these orbitals can be correctly determined by this theory.

  3. Mass Transfer with Chemical Reaction.

    Science.gov (United States)

    DeCoursey, W. J.

    1987-01-01

    Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

  4. Cross-reactivity and masqueraders in seafood reactions.

    Science.gov (United States)

    Banks, Taylor A; Gada, Satyen M

    2013-01-01

    Confounding variables play a significant role in many adverse seafood reactions and a clear understanding of these factors is important in properly characterizing reactions associated with potential masqueraders and mimics. Although the medical literature is replete with reviews of seafood hypersensitivity and reports of cross-reactive and newly characterized allergens, there has not been a recent effort to provide an updated overview of the several processes that may lead clinicians to draw incorrect conclusions in evaluating reported reactions to seafood. Ranging from seafood intoxications to other nonallergic or complex seafood reactions, these events can easily be misconstrued as representing a seafood IgE-mediated allergy. Among these are the more familiar topics of cross-reactivity and scombroid intoxication, and those with a still evolving understanding such as ciguatera fish poisoning and Anisakis reactions. This article seeks to provide an accessible but comprehensive summary of the relevant information surrounding these confounders in assessing adverse reactions to seafood. Such knowledge may be instrumental in unraveling complex or otherwise unclear presentations and aid clinicians in accurately evaluating and managing patients with reported seafood reactions.

  5. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian

    2013-01-01

    . This unfavorable change in reaction profile could be avoided by adding molecular sieves to the reaction mixture, thereby removing the water that is accumulated from the air and produced in the reaction in which dioxygen acts as the oxidizing agent. Not unexpectedly, the stirring rate, and hence uptake of air (O2...... on the scope of this reaction by using both 13C NMR and UV/Vis spectroscopic methods. The former method was used to study the kinetics of the coupling of aryl-substituted alkynes as the aryl carbon resonances of the reactants and products have similar NOEs and relaxation times. The reaction was found...

  6. Nuclear reactions in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M.; Rayet, M. (Universite Libre de Bruxelles (BE))

    1990-06-01

    At all times and at all astrophysical scales, nuclear reactions have played and continue to play a key role. This concerns the energetics as well as the production of nuclides (nucleosynthesis). After a brief review of the observed composition of various objects in the universe, and especially of the solar system, the basic ingredients that are required in order to build up models for the chemical evolution of galaxies are sketched. Special attention is paid to the evaluation of the stellar yields through an overview of the important burning episodes and nucleosynthetic processes that can develop in non-exploding or exploding stars. Emphasis is put on the remaining astrophysical and nuclear physics uncertainties that hamper a clear understanding of the observed characteristics, and especially compositions, of a large variety of astrophysical objects.

  7. Hypersensitivity reaction with deferasirox

    Directory of Open Access Journals (Sweden)

    Atul Sharma

    2015-01-01

    Full Text Available Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  8. Hypersensitivity reaction with deferasirox.

    Science.gov (United States)

    Sharma, Atul; Arora, Ekta; Singh, Harmanjit

    2015-01-01

    Thalassemias comprise a group of hereditary blood disorders. Thalassemia major presents with anemia within the first 2 years of life requiring frequent blood transfusions for sustaining life. Regular blood transfusions lead to iron overload-related complications. Prognosis of thalassemia has improved because of the availability of iron-chelating agents. Oral iron chelators are the mainstay of chelation therapy. Deferasirox is a new-generation oral iron chelator for once daily usage. We herein describe a patient of beta thalassemia major who developed an allergic manifestation in the form of erythematous pruritic skin rashes to the oral iron chelator deferasirox. This is a rare adverse reaction reported with deferasirox that led to a therapeutic dilemma in this particular case.

  9. Eikonal reaction theory

    CERN Document Server

    Yahiro, Masanobu; Minomo, Kosho

    2011-01-01

    We present an accurate method of treating the one-neutron removal reaction at intermediate incident energies induced by both nuclear and Coulomb interactions. In the method, the nuclear and Coulomb breakup processes are consistently treated by the method of continuum discretized coupled channels without making the adiabatic approximation to the Coulomb interaction, so that the removal cross section calculated never diverges. This method is applied to recently measured one-neutron removal cross section for $^{31}$Ne+$^{12}$C scattering at 230 MeV/nucleon and $^{31}$Ne+$^{208}$Pb scattering at 234 MeV/nucleon. The spectroscopic factor and the asymptotic normalization coefficient of the last neutron in $^{31}$Ne are evaluated.

  10. Nuclear reactions an introduction

    CERN Document Server

    Paetz gen. Schieck, Hans

    2014-01-01

    Nuclei and nuclear reactions offer a unique setting for investigating three (and in some cases even all four) of the fundamental forces in nature. Nuclei have been shown – mainly by performing scattering experiments with electrons, muons, and neutrinos – to be extended objects with complex internal structures: constituent quarks; gluons, whose exchange binds the quarks together; sea-quarks, the ubiquitous virtual quark-antiquark pairs and, last but not least, clouds of virtual mesons, surrounding an inner nuclear region, their exchange being the source of the nucleon-nucleon interaction.   The interplay between the (mostly attractive) hadronic nucleon-nucleon interaction and the repulsive Coulomb force is responsible for the existence of nuclei; their degree of stability, expressed in the details and limits of the chart of nuclides; their rich structure and the variety of their interactions. Despite the impressive successes of the classical nuclear models and of ab-initio approaches, there is clearly no ...

  11. 囊性纤维化跨膜转导调节因子(CFTR)表达率与人精子获能及顶体反应间相关性研究%Expression Percentage of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is Related to Human Sperm Capacitation and the Acrosome Reaction

    Institute of Scientific and Technical Information of China (English)

    李楚艳; 石其贤; 倪崖

    2014-01-01

    目的:研究人精子囊性纤维化跨膜转导调节因子(cystic fibrosis transmembrane conductanceregulator,CFTR)表达率与精子获能及顶体反应间的相关性.方法:通过间接免疫荧光染色法观察CFTR在人精子上的表达率,金霉素染色法评估精子获能及顶体反应.结果:CFTR定位在人精子赤道板上,随着CFTR表达率降低,精子获能率也随之降低,故CFTR表达率与人精子获能呈正相关(r=0.985,P<0.01),而且精子顶体反应率也随之减少,因此CFTR表达率与人精子顶体反应呈正相关(r=0.979,P<0.05).结论:人精子CFTR表达率与精子获能及顶体反应呈正相关.

  12. Immediate hypersensitivity reactions to penicillins and other betalactams.

    Science.gov (United States)

    Antúnez, C; Martín, E; Cornejo-García, J A; Blanca-Lopez, N; R-Pena, R; Mayorga, C; Torres, M J; Blanca, M

    2006-01-01

    Immediate hypersensitivity reactions to betalactams are IgE mediated and constitute the most frequent allergic reactions mediated by specific immunological mechanisms. IgE responses to benzyl penicillin (BP), the first antibiotic producing the benzyl penicilloyl structure (BPO), are characterized by a quick release of inflammatory mediators, resulting in anaphylactic shock, urticaria and angioedema. With the progressive appearance of other structures, comprising cephalosporins, carbapenems, monobactams and clavulanic acid, IgE selective responses and cross-reactivity reactions were observed. The diagnosis of betalactam hypersensitivity, classically based on skin testing with major and minor determinants of benzyl penicillin or in vitro IgE antibodies to BP, has been modified by the inclusion of different determinants generated from these compounds, for which amoxicillin (AX) is the most relevant, followed by cephalosporins. Some subjects develop positive responses to several betalactams, mostly within the same family, but others develop a selective response. These are relevant for the appropriate selection of antimicrobial drugs in patients who have immediate hypersensitivity to betalactams.

  13. The molecular chaperone HSPA2 plays a key role in regulating the expression of sperm surface receptors that mediate sperm-egg recognition.

    Science.gov (United States)

    Redgrove, Kate A; Nixon, Brett; Baker, Mark A; Hetherington, Louise; Baker, Gordon; Liu, De-Yi; Aitken, R John

    2012-01-01

    A common defect encountered in the spermatozoa of male infertility patients is an idiopathic failure of sperm-egg recognition. In order to resolve the molecular basis of this condition we have compared the proteomic profiles of spermatozoa exhibiting an impaired capacity for sperm-egg recognition with normal cells using label free mass spectrometry (MS)-based quantification. This analysis indicated that impaired sperm-zona binding was associated with reduced expression of the molecular chaperone, heat shock 70 kDa protein 2 (HSPA2), from the sperm proteome. Western blot analysis confirmed this observation in independent patients and demonstrated that the defect did not extend to other members of the HSP70 family. HSPA2 was present in the acrosomal domain of human spermatozoa as a major component of 5 large molecular mass complexes, the most dominant of which was found to contain HSPA2 in close association with just two other proteins, sperm adhesion molecule 1 (SPAM1) and arylsulfatase A (ARSA), both of which that have previously been implicated in sperm-egg interaction. The interaction between SPAM1, ARSA and HSPA2 in a multimeric complex mediating sperm-egg interaction, coupled with the complete failure of this process when HSPA2 is depleted in infertile patients, provides new insights into the mechanisms by which sperm function is impaired in cases of male infertility.

  14. Nanofluids mediating surface forces.

    Science.gov (United States)

    Pilkington, Georgia A; Briscoe, Wuge H

    2012-11-01

    Fluids containing nanostructures, known as nanofluids, are increasingly found in a wide array of applications due to their unique physical properties as compared with their base fluids and larger colloidal suspensions. With several tuneable parameters such as the size, shape and surface chemistry of nanostructures, as well as numerous base fluids available, nanofluids also offer a new paradigm for mediating surface forces. Other properties such as local surface plasmon resonance and size dependent magnetism of nanostructures also present novel mechanisms for imparting tuneable surface interactions. However, our fundamental understanding, experimentally and theoretically, of how these parameters might affect surface forces remains incomplete. Here we review recent results on equilibrium and dynamic surface forces between macroscopic surfaces in nanofluids, highlighting the overriding trends in the correlation between the physical parameters that characterise nanofluids and the surface forces they mediate. We also discuss the challenges that confront existing surface force knowledge as a result of this new paradigm.

  15. The mediatization of journalism

    Directory of Open Access Journals (Sweden)

    Aske Kammer

    2014-06-01

    Full Text Available Proposing an explanation of current macro-sociological changes and institutional transformations in journalism, this article argues that journalism is currently undergoing a process of mediatization. Drawing upon the international research literature as well as statements from interviews with news workers working on Danish news websites, the article examines four current trends in journalism that are closely connected to the rise of news on the web, namely the use of the affordances of news websites, radical commercialization, increased audience participation in news production, and the increased multi-skilling and simultaneous de-skilling of journalists. Taken together, these trends reflect a process through which journalism increasingly subsumes itself to the logic of the media, suggesting mediatization as an adequate explanatory framework. One implication of such a process is that journalism seems to be transforming from an occupational profession into an organizational one.

  16. [Healthcare mediation model for nerologists].

    Science.gov (United States)

    Ando, Tetsuo

    2011-11-01

    Mediation offers a process by which two parties work towards an agreement with the aid of a neutral third party. Physicians and nurses can apply healthcare mediation model to ordinary medical practice for preventing conflict. Communication using mediation skills improves patient-physician relationship, and prevents medical malpractice and conflict.

  17. Surface Mediated Photocatalysis.

    Science.gov (United States)

    1987-12-01

    Bipolar Photoelectrodes," M.A. Fox, Nouv. J. Chim. 1987, II, 129. 4. "Effect of Cosolvent Additives on Relative Rates of Photooxidation on...Semiconductor Surfaces," D.D. Sackett, M.A. Fox, J. Phys. Org. Chem, 19_8, in press. 5. "Selectivity in the Semiconductor-Mediated Photooxidation of Polyols ...surfaced properties of the heteropolytungstates were varied. The conceptual mechanistic picture involved in the heteropolyoxo induced photooxidations

  18. Kinetics and mechanism of the reaction between thiourea and iodate in unbuffered medium

    Institute of Scientific and Technical Information of China (English)

    WANG; Shun; LIN; Juanjuan; CHEN; Fan; HU; Maolin; HU; Xinge

    2004-01-01

    The reaction between iodate and thiourea has been studied in an unbuffered acidic medium. In excess iodate the reaction shows not only oligooscillations in pH, Pt potential and the concentration of iodide ion, [I-], but also an initial induction period which has the linear relation with initial pH. At the end of the induction period, [I-] decreases sharply and a yellow coloration (due to iodine) appears transiently. While in excess thiourea iodine is produced and finally consumed, leaving milky deposits (due to sulfur) at the end of the reaction. The induction period from the start of the reaction to the maximum of [I2] is also directly proportional to initial pH. A 14-step mechanism, including a H+-mediated preequalibrium, Dusman reaction, iodine-sulfur reactions and sulfur-sulfur reactions, is proposed. Computer simulations using this mechanism give good agreement with experiments.

  19. The Enzymology of Organic Transformations: A Survey of Name Reactions in Biological Systems.

    Science.gov (United States)

    Lin, Chia-I; McCarty, Reid M; Liu, Hung-Wen

    2017-03-20

    Chemical reactions that are named in honor of their true, or at least perceived, discoverers are known as "name reactions". This Review is a collection of biological representatives of named chemical reactions. Emphasis is placed on reaction types and catalytic mechanisms that showcase both the chemical diversity in natural product biosynthesis as well as the parallels with synthetic organic chemistry. An attempt has been made, whenever possible, to describe the enzymatic mechanisms of catalysis within the context of their synthetic counterparts and to discuss the mechanistic hypotheses for those reactions that are currently active areas of investigation. This Review has been categorized by reaction type, for example condensation, nucleophilic addition, reduction and oxidation, substitution, carboxylation, radical-mediated, and rearrangements, which are subdivided by name reactions.

  20. Signal transduction pathways in guinea pig sperm

    Institute of Scientific and Technical Information of China (English)

    李明文; 焦日; 孙青原; 胡国俊; 段崇文; 刘辉; 宋祥芬; 陈大元

    1996-01-01

    Trifluoperazine (TFP), the antagonist of calmodulin (CaM). significantly stimulated the capacitation and acrosome reaction of guinea pig spermatozoa at the concentration of 10-100μmol/L, independent of the external Ca2+. Forskolin, dbcAMP and caffeine evidently promoted the occurrence of acrosome reaction of spermatozoa at early capacitation stage (5 h) in nonsynchronous system but not in synchronous system. If the spermatozoa were capacitated for 15 h in synchronous system, the above three drugs significantly stimulated acrosome reaction in a Ca2+-independent manner. Protein kinase C activators, i.e. phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB) did not influence the occurrence of acrosome reaction of spermatozoa at early capacitation stage, but significantly increased the acrosome reaction rate in capacitated spermatozoa in a Ca2+-independent manner. In contrast. PKC inhibitor staurosporine significantly inhibited the occurrence of acrosome reaction.

  1. Enzyme mediated synthesis of polypyrrole in the presence of chondroitin sulfate and redox mediators of natural origin

    Energy Technology Data Exchange (ETDEWEB)

    Grijalva-Bustamante, G.A. [Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, CP 83000 Hermosillo, Sonora (Mexico); Evans-Villegas, A.G. [Departamento de Ciencias Químico Biológicas, Universidad de Sonora, CP 83000 Hermosillo, Sonora (Mexico); Castillo-Castro, T. del, E-mail: terecat@polimeros.uson.mx [Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, CP 83000 Hermosillo, Sonora (Mexico); Castillo-Ortega, M.M. [Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, CP 83000 Hermosillo, Sonora (Mexico); Cruz-Silva, R. [Research Center for Exotic Nanocarbons, Shinshu University, 4-17-1 Wakasato, 380-8553, Nagano (Japan); Huerta, F. [Departamento Ingeniería Textil y Papelera, Universitat Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1, E-03801 Alcoy (Spain); Morallón, E. [Departamento Química Física e Instituto Universitario de Materiales, Universidad de Alicante, Ap. 99, E-03080 Alicante (Spain)

    2016-06-01

    Polypyrrole (PPy) was synthesized by enzyme mediated oxidation of pyrrole using naturally occurring compounds as redox mediators. The catalytic mechanism is an enzymatic cascade reaction in which hydrogen peroxide is the oxidizer and soybean peroxidase, in the presence of acetosyringone, syringaldehyde or vanillin, acts as a natural catalysts. The effect of the initial reaction composition on the polymerization yield and electrical conductivity of PPy was analyzed. Morphology of the PPy particles was studied by scanning electron microscopy and transmission electron microscopy whereas the chemical structure was studied by X-ray photoelectron and Fourier transformed infrared spectroscopic techniques. The redox mediators increased the polymerization yield without a significant modification of the electronic structure of PPy. The highest conductivity of PPy was reached when chondroitin sulfate was used simultaneously as dopant and template during pyrrole polymerization. Electroactive properties of PPy obtained from natural precursors were successfully used in the amperometric quantification of uric acid concentrations. PPy increases the amperometric sensitivity of carbon nanotube screen-printed electrodes toward uric acid detection. - Highlights: • A new method of pyrrole polymerization using naturally occurring redox mediators and doping agents was studied. • The catalytic efficiency of different redox mediators toward pyrrole oxidation was evaluated. • Two different naturally occurring polymers were studied as bifunctional steric stabilizer/doping agents. • Polypyrrole improves the amperometric response of carbon nanotube screen printed electrodes toward uric acid sensing.

  2. Resonance Reaction in Diffusion-Influenced Bimolecular Reactions

    CERN Document Server

    Kolb, Jakob J; Dzubiella, Joachim

    2016-01-01

    We investigate the influence of a stochastically fluctuating step-barrier potential on bimolecular reaction rates by exact analytical theory and stochastic simulations. We demonstrate that the system exhibits a new resonant reaction behavior with rate enhancement if an appropriately defined fluctuation decay length is of the order of the system size. Importantly, we find that in the proximity of resonance the standard reciprocal additivity law for diffusion and surface reaction rates is violated due to the dynamical coupling of multiple kinetic processes. Together, these findings may have important repercussions on the correct interpretation of various kinetic reaction problems in complex systems, as, e.g., in biomolecular association or catalysis.

  3. Irreversible sortase A-mediated ligation driven by diketopiperazine formation.

    Science.gov (United States)

    Liu, Fa; Luo, Ethan Y; Flora, David B; Mezo, Adam R

    2014-01-17

    Sortase A (SrtA)-mediated ligation has emerged as an attractive tool in bioorganic chemistry attributing to the remarkable specificity of the ligation reaction and the physiological reaction conditions. However, the reversible nature of this reaction limits the efficiency of the ligation reaction and has become a significant constraint to its more widespread use. We report herein a novel set of SrtA substrates (LPETGG-isoacyl-Ser and LPETGG-isoacyl-Hse) that can be irreversibly ligated to N-terminal Gly-containing moieties via the deactivation of the SrtA-excised peptide fragment through diketopiperazine (DKP) formation. The convenience of the synthetic procedure and the stability of the substrates in the ligation buffer suggest that both LPETGG-isoacyl-Ser and LPETGG-isoacyl-Hse are valuable alternatives to existing irreversible SrtA substrate sequences.

  4. NIF Gamma Reaction History

    Science.gov (United States)

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.

    2010-11-01

    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  5. Hemolytic Transfusion Reactions

    Directory of Open Access Journals (Sweden)

    Fatih Mehmet Azık

    2011-12-01

    Full Text Available The prevalence of fatal hemolytic transfusion reactions (HTRs is approximately 1:200000 per unit. Acute HTRs occur during or within 24 h after administration of a blood product. Transfusion of incompatible red blood cells (RBCs, and, more rarely, of a large volume of incompatible plasma usually are the causative agents. Delayed HTRs are caused by a secondary immune response to an antigen on the donor’s RBCs. Different mechanisms lead to intra- and extravascular hemolysis, such as complete complement activation, phagocytosis of RBCs covered with C3b by macrophages after incomplete complement activation, or destruction of RBCs covered only with IgG by direct cell to cell contact with K cells. The clinical consequences of HTRs are triggered via several pathophysiological pathways. Formation of anaphylatoxins, release of cytokines causing a systemic inflammatory response syndrome, activation of the kinin system, the intrinsic clotting cascade and fibrinolysis result in hypotension, disseminated intravascular coagulation, diffuse bleeding, and disruption of microcirculation leading to renal failure and shock. In this review, the symptoms of HTR are introduced, laboratory investigations and treatment are described, and some recommendations for prevention are given. (Journal of Current Pediatrics 2011; 9: 127-32

  6. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU TaJung

    2001-01-01

    @@ The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.

  7. Microwave-Accelerated Organic Reactions

    Institute of Scientific and Technical Information of China (English)

    LU; TaJung

    2001-01-01

    The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted 1,3-dipolar cycloaddition reaction of nitrile oxides with allylic alcohols, the cleavage reaction of 1,3-diketones under alkaline conditions, and the formation of carbamates from isocyanates with alcohols. The reactions carried out under microwave irradiation, in general, required considerably less reaction time and afforded the desired products in higher yields than those under classical conditions. In all the cases we have studied, the procedures are simplified, the purity of the products are higher, and the cost of reaction is greatly reduced employing microwave.  ……

  8. Severe serum sickness reaction to oral and intramuscular penicillin.

    Science.gov (United States)

    Clark, Brychan M; Kotti, George H; Shah, Anand D; Conger, Nicholas G

    2006-05-01

    Serum sickness is a type III hypersensitivity reaction mediated by immune complex deposition with subsequent complement activation, small-vessel vasculitis, and tissue inflammation. Although the overall incidence of serum sickness is declining because of decreased use of heterologous sera and improved vaccinations, rare sporadic cases of serum sickness from nonprotein drugs such as penicillins continue to occur. Drug-induced serum sickness is usually self-limited, with symptoms lasting only 1-2 weeks before resolving. We report an unusual case of a severe and prolonged serum sickness reaction that occurred after exposure to an intramuscular penicillin depot injection (probable relationship by Naranjo score) and discuss how pharmacokinetics may have played a role. Clinicians should be familiar with serum sickness reactions particularly as they relate to long-acting penicillin preparations. Accurate diagnosis in conjunction with cessation of drug exposure and prompt initiation of antiinflammatory treatment with corticosteroids can produce complete recovery

  9. What carries a mediation process? Configural analysis of mediation.

    Science.gov (United States)

    von Eye, Alexander; Mun, Eun Young; Mair, Patrick

    2009-09-01

    Mediation is a process that links a predictor and a criterion via a mediator variable. Mediation can be full or partial. This well-established definition operates at the level of variables even if they are categorical. In this article, two new approaches to the analysis of mediation are proposed. Both of these approaches focus on the analysis of categorical variables. The first involves mediation analysis at the level of configurations instead of variables. Thus, mediation can be incorporated into the arsenal of methods of analysis for person-oriented research. Second, it is proposed that Configural Frequency Analysis (CFA) can be used for both exploration and confirmation of mediation relationships among categorical variables. The implications of using CFA are first that mediation hypotheses can be tested at the level of individual configurations instead of variables. Second, this approach leaves the door open for different types of mediation processes to exist within the same set. Using a data example, it is illustrated that aggregate-level analysis can overlook mediation processes that operate at the level of individual configurations.

  10. Radiation reaction in fusion plasmas.

    Science.gov (United States)

    Hazeltine, R D; Mahajan, S M

    2004-10-01

    The effects of a radiation reaction on thermal electrons in a magnetically confined plasma, with parameters typical of planned burning plasma experiments, are studied. A fully relativistic kinetic equation that includes the radiation reaction is derived. The associated rate of phase-space contraction is computed and the relative importance of the radiation reaction in phase space is estimated. A consideration of the moments of the radiation reaction force show that its effects are typically small in reactor-grade confined plasmas, but not necessarily insignificant.

  11. Kinematically complete chemical reaction dynamics

    Science.gov (United States)

    Trippel, S.; Stei, M.; Otto, R.; Hlavenka, P.; Mikosch, J.; Eichhorn, C.; Lourderaj, U.; Zhang, J. X.; Hase, W. L.; Weidemüller, M.; Wester, R.

    2009-11-01

    Kinematically complete studies of molecular reactions offer an unprecedented level of insight into the dynamics and the different mechanisms by which chemical reactions occur. We have developed a scheme to study ion-molecule reactions by velocity map imaging at very low collision energies. Results for the elementary nucleophilic substitution (SN2) reaction Cl- + CH3I → ClCH3 + I- are presented and compared to high-level direct dynamics trajectory calculations. Furthermore, an improved design of the crossed-beam imaging spectrometer with full three-dimensional measurement capabilities is discussed and characterization measurements using photoionization of NH3 and photodissociation of CH3I are presented.

  12. Speeding chemical reactions by focusing

    CERN Document Server

    Lacasta, A M; Sancho, J M; Lindenberg, K

    2012-01-01

    We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate (t to the power -1/2) to very close to the perfect mixing rate, (t to the power -1).

  13. Involvement of Histamine and RhoA/ROCK in Penicillin Immediate Hypersensitivity Reactions.

    Science.gov (United States)

    Han, Jiayin; Yi, Yan; Li, Chunying; Zhang, Yushi; Wang, Lianmei; Zhao, Yong; Pan, Chen; Liang, Aihua

    2016-09-13

    The mechanism of penicillin immediate hypersensitivity reactions has not been completely elucidated. These reactions are generally considered to be mediated by IgE, but penicillin-specific IgE could not be detected in most cases. This study demonstrated that penicillin was able to cause vascular hyperpermeability in a mouse model mimicking clinical symptoms of penicillin immediate hypersensitivity reactions. The first exposure to penicillin also induced immediate edema and exudative reactions in ears and lungs of mice in a dose-dependent manner. Vasodilation was noted in microvessels in ears. These reactions were unlikely to be immune-mediated reactions, because no penicillin-specific IgE was produced. Furthermore, penicillin treatment directly elicited rapid histamine release. Penicillin also led to F-actin reorganization in human umbilical vein endothelial cells and increased the permeability of the endothelial monolayer. Activation of the RhoA/ROCK signaling pathway was observed in ears and lungs of mice and in endothelial cells after treatment with penicillin. Both an anti-histamine agent and a ROCK inhibitor attenuated penicillin immediate hypersensitivity reactions in mice. This study presents a novel mechanism of penicillin immediate hypersensitivity reactions and suggests a potential preventive approach against these reactions.

  14. Dynamic Reaction Figures: An Integrative Vehicle for Understanding Chemical Reactions

    Science.gov (United States)

    Schultz, Emeric

    2008-01-01

    A highly flexible learning tool, referred to as a dynamic reaction figure, is described. Application of these figures can (i) yield the correct chemical equation by simply following a set of menu driven directions; (ii) present the underlying "mechanism" in chemical reactions; and (iii) help to solve quantitative problems in a number of different…

  15. Organolanthanide reagents and the Mukaiyama reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gong, L.

    1989-01-01

    The bis(pentamethylcyclopentadienyl) lutetium halide complex ((C/sub 5/Me/sub 5/)/sub 2/LuCl/center dot/THF) was synthesized and characterized. The crystal structure of this complex shows that the Lu is at the center of a distorted tetrahedron consisting of the centroids of two cyclopentadienyl rings, the oxygen atom of a tetrahydrofuran molecule and a chlorine atom. /sup 1/H NMR studies of toluene-d/sub 8/ solutions of (C/sub 5/Me/sub 5/LuCl(THF) + THF, (TMS/sub 2/CP)/sub 2/LuCl(THF) + THF, and (MeCp)/sub 2/LuCl(THF) + THF at various temperatures showed exchange processes between co- ordinated THF and free THF with average values of ..delta..G/sup ne/ of 13.0 /+-/ 0.3 kcal/mol, 11.1 /+-/ 0.1 kcal/mol and <11 kcal/mol at 0/degree/C, respectively. It has been found that under the influence of a catalytic amount (1--5 mol %) of (TMS/sub 2/Cp)/sub 2/YbCl dimer, silyl enol ethers (R/sub 1/R/sub 2/C = C(OR/sub 3/)OSiMe/sub 3/)) react with benzaldehyde smoothly in dichloromethane at room temperature, giving >99% of the aldol silyl ether (isolated yield: 90%) within 3 h. At /minus/78/degrees/C, the reaction gives kinetically controlled diastereoselectivity, which was not observed in the TiCl/sub 4/-mediated aldol reaction. The use of organoytterbium enolates shows promise result with respect to increased stereoselectivity, and indicates the importance of the bulky ligands on the metal center. In addition, Yb(III) species can retard retroaldol reaction owing to its mild Lewis acidity. 118 refs., 14 figs., 30 tabs.

  16. Loop-mediated isothermal amplification for detection of nucleic acids.

    Science.gov (United States)

    Tanner, Nathan A; Evans, Thomas C

    2014-01-06

    Sequence-specific isothermal nucleic acid amplification techniques are ideally suited for use in molecular diagnostic applications because they do not require thermal cycling equipment and the reactions are typically fast. One of the most widely cited isothermal techniques is termed loop-mediated isothermal amplification (LAMP). This protocol allows amplification times as fast as 5 to 10 min. Furthermore, various methodologies to detect amplification have been applied to LAMP to increase its utility for the point-of-care market. Basic LAMP protocols are provided herein for detection of specific DNA and RNA targets, along with a method to perform multiplex LAMP reactions, permitting even greater flexibility from this powerful technique.

  17. Influence of Ionic Liquids on an Iron(III) Catalyzed Three-Component Coupling/Hydroarylation/Dehydrogenation Tandem Reaction.

    Science.gov (United States)

    Muntzeck, Maren; Wilhelm, René

    2016-06-01

    A three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline and phenylacetylene to a quinoline derivate was catalyzed by an iron-containing ionic liquid. The reaction was air mediated and could be performed under neat conditions. The iron(III) of the ionic liquid was the oxidizing species.

  18. Exact probability distributions of selected species in stochastic chemical reaction networks.

    Science.gov (United States)

    López-Caamal, Fernando; Marquez-Lago, Tatiana T

    2014-09-01

    Chemical reactions are discrete, stochastic events. As such, the species' molecular numbers can be described by an associated master equation. However, handling such an equation may become difficult due to the large size of reaction networks. A commonly used approach to forecast the behaviour of reaction networks is to perform computational simulations of such systems and analyse their outcome statistically. This approach, however, might require high computational costs to provide accurate results. In this paper we opt for an analytical approach to obtain the time-dependent solution of the Chemical Master Equation for selected species in a general reaction network. When the reaction networks are composed exclusively of zeroth and first-order reactions, this analytical approach significantly alleviates the computational burden required by simulation-based methods. By building upon these analytical solutions, we analyse a general monomolecular reaction network with an arbitrary number of species to obtain the exact marginal probability distribution for selected species. Additionally, we study two particular topologies of monomolecular reaction networks, namely (i) an unbranched chain of monomolecular reactions with and without synthesis and degradation reactions and (ii) a circular chain of monomolecular reactions. We illustrate our methodology and alternative ways to use it for non-linear systems by analysing a protein autoactivation mechanism. Later, we compare the computational load required for the implementation of our results and a pure computational approach to analyse an unbranched chain of monomolecular reactions. Finally, we study calcium ions gates in the sarco/endoplasmic reticulum mediated by ryanodine receptors.

  19. Microscopic effective reaction theory for deuteron-induced reactions

    Science.gov (United States)

    Neoh, Yuen Sim; Yoshida, Kazuki; Minomo, Kosho; Ogata, Kazuyuki

    2016-10-01

    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model space characterized by a p +n +A three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A . The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels (CDCC) method, and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on 58Ni and 208Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  20. Microscopic effective reaction theory for deuteron-induced reactions

    CERN Document Server

    Neoh, Yuen Sim; Minomo, Kosho; Ogata, Kazuyuki

    2016-01-01

    The microscopic effective reaction theory is applied to deuteron-induced reactions. A reaction model-space characterized by a $p+n+{\\rm A}$ three-body model is adopted, where A is the target nucleus, and the nucleon-target potential is described by a microscopic folding model based on an effective nucleon-nucleon interaction in nuclear medium and a one-body nuclear density of A. The three-body scattering wave function in the model space is obtained with the continuum-discretized coupled-channels method (CDCC), and the eikonal reaction theory (ERT), an extension of CDCC, is applied to the calculation of neutron removal cross sections. Elastic scattering cross sections of deuteron on $^{58}$Ni and $^{208}$Pb target nuclei at several energies are compared with experimental data. The total reaction cross sections and the neutron removal cross sections at 56 MeV on 14 target nuclei are calculated and compared with experimental values.

  1. Progress in microscopic direct reaction modeling of nucleon induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dupuis, M.; Bauge, E.; Hilaire, S.; Lechaftois, F.; Peru, S.; Pillet, N.; Robin, C. [CEA, DAM, DIF, Arpajon (France)

    2015-12-15

    A microscopic nuclear reaction model is applied to neutron elastic and direct inelastic scatterings, and pre-equilibrium reaction. The JLM folding model is used with nuclear structure information calculated within the quasi-particle random phase approximation implemented with the Gogny D1S interaction. The folding model for direct inelastic scattering is extended to include rearrangement corrections stemming from both isoscalar and isovector density variations occurring during a transition. The quality of the predicted (n,n), (n,n{sup '}), (n,xn) and (n,n{sup '}γ) cross sections, as well as the generality of the present microscopic approach, shows that it is a powerful tool that can help improving nuclear reactions data quality. Short- and long-term perspectives are drawn to extend the present approach to more systems, to include missing reactions mechanisms, and to consistently treat both structure and reaction problems. (orig.)

  2. Urban Songlines as Mediator

    DEFF Research Database (Denmark)

    Corlin, Anne

    2016-01-01

    The aim of this paper is to present an investigation of the method The Urban Songlines Book and how it works as a mediator for mapping the experienced space. The method contains a combination of aerial maps, photographs, and interviews as a way to understand the respondent´s use, relations...... and experiences of their neighborhood and the city. Through a presentation of the origin of the method, a description of the conducted study, and an analysis of the process in relation to theories about participatory design, social design, ANT and architectural sociology, the paper reveals how this method...

  3. Sociocultural mediators of remembering

    DEFF Research Database (Denmark)

    Wagoner, Brady; Gillespie, Alex

    2014-01-01

    , questioning and deferring contribute to the transformation and conventionalization of the material. These diverse sociocultural mediators are integrated into a partially coherent recollection by participants self-reflecting, or as Bartlett termed it, turning around upon their schemas. We demonstrate...... that this self-reflection is both a social and a psychological process, occurring because participants are responding to their own utterances in the same way that they respond to the utterances of other people. These empirical findings are used to make a case for using discursive data to look not only...

  4. Mediatization and Government Communication

    DEFF Research Database (Denmark)

    Laursen, Bo; Valentini, Chiara

    2015-01-01

    in the light of mediatization and government communication theories. Without one pan-European public sphere, the European Parliament, like the other European Union (EU) institutions, competes with national actors for the news media’s attention in the EU’s twenty-eight national public spheres, where EU affairs......, and particularly into the thinking that guides the efforts of these European Parliament officials to increase European citizens’ awareness of, and support for, the European Parliament that is meant to voice the citizens’ concerns in political processes at the EU level....

  5. Computer Mediated Communication

    Science.gov (United States)

    Fano, Robert M.

    1984-08-01

    The use of computers in organizations is discussed in terms of its present and potential role in facilitating and mediating communication between people. This approach clarifies the impact that computers may have on the operation of organizations and on the individuals comprising them. Communication, which is essential to collaborative activities, must be properly controlled to protect individual and group privacy, which is equally essential. Our understanding of the human and organizational aspects of controlling communication and access to information presently lags behind our technical ability to implement the controls that may be needed.

  6. Holographic Gauge Mediation

    Energy Technology Data Exchange (ETDEWEB)

    Benini, Francesco; /Princeton U.; Dymarsky, Anatoly; /Stanford U., ITP; Franco, Sebastian; /Santa Barbara, KITP; Kachru, Shamit; Simic, Dusan; /Stanford U., ITP /SLAC; Verlinde, Herman; /Princeton, Inst. Advanced Study

    2009-06-19

    We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain 'messenger mesons,' which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.

  7. Surface-Mediated Photocatalysis

    Science.gov (United States)

    1992-02-04

    Photocatalysis 6. AUTHOR(S) DIMarye Anne Fox E -LECTE ’ / 7. PERFORMING ORGANIZATION NAME(S) AND AD ES). 8. PERFORMING ORGANIZATION REPORT NUMBER University of...Form 298 (Rev 2-89) Prescr d bv ANJ std Z39.1s 291-102 j Final Report on Surface-Mediated Photocatalysis "a,. . ARO Proposal No. 28298-CH u - Work from...Produced by Anodic Oxidation and by Photoelectrochemical Activation of TiO2 ," Marye Anne Fox and Karl L. Worthen, Chem. Mater. 1991, 3, 253. "Surface

  8. 45 CFR 16.18 - Mediation.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Mediation. 16.18 Section 16.18 Public Welfare... BOARD § 16.18 Mediation. (a) In cases pending before the Board. If the Board decides that mediation... mediation techniques and will provide or assist in selecting a mediator. The mediator may take any...

  9. Mediation Revisited: The Interactive Organization of Mediation in Learning Environments

    OpenAIRE

    Pekarek Doehler, Simona

    2013-01-01

    This article is concerned with the social organization of mediation in learning environments. It seeks to further articulate the sociocultural notion of mediation in sociointeractional terms, combining insights from the sociocultural approach to cognition and the microinteractionist, especially ethnomethodological approach to social activities. A microanalysis of mediation in communicative 2nd-language classroom activities where the task at hand is the management of interaction itself is pres...

  10. Magnetically mediated thermoacoustic imaging

    Science.gov (United States)

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2014-03-01

    In this paper, alternating magnetic field is explored for inducing thermoacoustic effect on dielectric objects. Termed as magnetically mediated thermo-acoustic (MMTA) effect that provides a contrast in conductivity, this approach employs magnetic resonance for delivering energy to a desired location by applying a large transient current at radio frequency below 50MHz to a compact magnetically resonant coil. The alternating magnetic field induces large electric field inside conductive objects, which then undergoes joule heating and emanates acoustic signal thermo-elastically. The magnetic mediation approach with low radio frequency can potentially provide deeper penetration than microwave radiation due to the non-magnetic nature of human body and therefore extend thermoacoustic imaging to deep laid organs. Both incoherent time domain method that applies a pulsed radio frequency current and coherent frequency domain approach that employs a linear chirp signal to modulate the envelop of the current are discussed. Owing to the coherent processing nature, the latter approach is capable of achieving much better signal to noise ratio and therefore potential for portable imaging system. Phantom experiments are carried out to demonstrate the signal generation together with some preliminary imaging results. Ex-vivo tissue studies are also investigated.

  11. Allergic reactions to insect secretions.

    Science.gov (United States)

    Pecquet, Catherine

    2013-01-01

    Some products derived from insects can induce allergic reactions. The main characteristics of some products from honeybees, cochineal and silkworms are summarised here. We review allergic reactions from honey-derived products (propolis, wax, royal jelly), from cochineal products (shellac and carmine) and from silk : clinical features, allergological investigations and allergens if they are known.

  12. The Paterno-Buchi reaction

    DEFF Research Database (Denmark)

    Brogaard, Rasmus Yding; Schalk, Oliver; Boguslavskiy, Andrey E.

    2012-01-01

    The Paternò-Büchi (PB) reaction between an excited carbonyl compound and an alkene has been widely studied, but so far little is known about the excited-state dynamics of the reaction. In this investigation, we used a compound in which a formyl and a vinyl group are attached to a [2.2]paracycloph...

  13. Adverse Reactions to Hallucinogenic Drugs.

    Science.gov (United States)

    Meyer, Roger E. , Ed.

    This reports a conference of psychologists, psychiatrists, geneticists and others concerned with the biological and psychological effects of lysergic acid diethylamide and other hallucinogenic drugs. Clinical data are presented on adverse drug reactions. The difficulty of determining the causes of adverse reactions is discussed, as are different…

  14. "Greening up" the Suzuki Reaction

    Science.gov (United States)

    Aktoudianakis, Evangelos; Chan, Elton; Edward, Amanda R.; Jarosz, Isabel; Lee, Vicki; Mui, Leo; Thatipamala, Sonya S.; Dicks, Andrew P.

    2008-01-01

    This article describes the rapid, green synthesis of a biaryl compound (4-phenylphenol) via a Pd(0)-catalyzed Suzuki cross-coupling reaction in water. Mild reaction conditions and operational simplicity makes this experiment especially amenable to both mid- and upper-level undergraduates. The methodology exposes students to purely aqueous…

  15. Free Radical Reactions in Food.

    Science.gov (United States)

    Taub, Irwin A.

    1984-01-01

    Discusses reactions of free radicals that determine the chemistry of many fresh, processed, and stored foods. Focuses on reactions involving ascorbic acid, myoglobin, and palmitate radicals as representative radicals derived from a vitamin, metallo-protein, and saturated lipid. Basic concepts related to free radical structure, formation, and…

  16. [Skin reactions to tattoo ink].

    Science.gov (United States)

    Piérard-Franchimont, C; Hermanns, J-F; Piérard, G E

    2011-01-01

    Ritual and artistic tattoos rely on the use of numerous pigments which are not all entirely inert once placed in the dermis. The compositions of some tattoo inks are identified. However, new but less well identified compounds appear on the market. Allergic reactions can be present under different aspects. They may correspond to allergic contact dermatitis or to photodermatitis. Other reactions include allergic hypersensitivity reactions as well as lichenoid, granulomatous or pseudolymphoma reactions. Pulsed light and laser are typically used for regular tattoo removal. These procedures are not indicated in inflamed tattoos. Indeed, the pigment dispersed during photolysis may perpetuate the reaction. Pseudotattoos due to the stratum corneum staining are frequently responsible for photoeczema.

  17. Limits for Stochastic Reaction Networks

    DEFF Research Database (Denmark)

    Cappelletti, Daniele

    at a certain time are stochastically modelled by means of a continuous-time Markov chain. Our work concerns primarily stochastic reaction systems, and their asymptotic properties. In Paper I, we consider a reaction system with intermediate species, i.e. species that are produced and fast degraded along a path...... of the stochastic reaction systems. Specically, we build a theory for stochastic reaction systems that is parallel to the deciency zero theory for deterministic systems, which dates back to the 70s. A deciency theory for stochastic reaction systems was missing, and few results connecting deciency and stochastic....... Such species, in the deterministic modelling regime, assume always the same value at any positive steady state. In the stochastic setting, we prove that, if the initial condition is a point in the basin of attraction of a positive steady state of the corresponding deterministic model and tends to innity...

  18. Synthesis of C-4 Substituted Amido Nicotine Derivatives via Copper(I)- and (II)-Catalyzed Cross-Coupling Reactions.

    Science.gov (United States)

    Zhu, Jiancheng; Enamorado, Monica F; Comins, Daniel L

    2016-11-18

    The syntheses of seven novel amido nicotine derivatives 12-18 from (S)-nicotine are presented. (S)-Nicotine and (S)-6-chloronicotine derivatives were cross-coupled with the corresponding amides 6-10 at the C-4 position of the pyridine ring via copper(I)-mediated reactions. Derivatives 16-18 were also obtained via copper(II)-mediated reactions from (S)-nicotine containing a C-4 boronic acid pinacol ester group. The optimization of reaction conditions for both routes provided a useful method for preparing C-4 amide-containing nicotine analogs.

  19. Nitrite attenuated hypochlorous acid-mediated heme degradation in hemoglobin.

    Science.gov (United States)

    Lu, Naihao; Li, Jiayu; Ren, Xiaoming; Tian, Rong; Peng, Yi-Yuan

    2015-08-05

    Hypochlorous acid (HOCl) is elevated in many inflammatory diseases and causes the accumulation of free iron. Through the Fenton reaction, free iron has the ability to generate free radicals and subsequently is toxic. Recent studies have demonstrated that HOCl participates in heme destruction of hemoglobin (Hb) and free iron release. In this study, it was showed that nitrite (NO2(-)) could prevent HOCl-mediated Hb heme destruction and free iron release. Also, NO2(-) prevented HOCl-mediated loss of Hb peroxidase activity. After the NO2(-)/HOCl treatment, Tyr 42 in α-chain was found to be nitrated in Hb, attenuating the electron transferring abilities of phenolic compounds. The protective effects of NO2(-) on HOCl-induced heme destruction were attributed to its reduction of ferryl Hb and/or direct scavenging of HOCl. Therefore, NO2(-) could show protective effects in some inflammatory diseases by preventing HOCl-mediated heme destruction of hemoproteins and free iron release.

  20. [Mechanism of mediators in human skin. Pharmacoanalysis and therapeutic aspects].

    Science.gov (United States)

    Stüttgen, G

    1977-06-01

    Under physiological and pathological conditions, the skin is influenced by tissue hormones (biogenic amines, kinines, prostaglandines), neuro-hormones (acetylcholine, catecholamines) and by proteins as complement. The combination of neurological stimulation with a series of self-propagating metabolic changes, shows new aspects of tissue reaction. Histamine triggers a serie of mediators as kinines and prostaglandines. Due to their influence on mediators and their effects on regulatory mechanisms the cyclic nucleotides can serve as model substances for the development of therapeutic processes for dermatological as well as for other disorders. The influence on mediator-systems by topical treatment and proven permeability of such substances is of extreme importance for the future development of local dermatological therapy.

  1. Receptor-Mediated Drug Delivery Systems Targeting to Glioma

    Directory of Open Access Journals (Sweden)

    Shanshan Wang

    2015-12-01

    Full Text Available Glioma has been considered to be the most frequent primary tumor within the central nervous system (CNS. The complexity of glioma, especially the existence of the blood-brain barrier (BBB, makes the survival and prognosis of glioma remain poor even after a standard treatment based on surgery, radiotherapy, and chemotherapy. This provides a rationale for the development of some novel therapeutic strategies. Among them, receptor-mediated drug delivery is a specific pattern taking advantage of differential expression of receptors between tumors and normal tissues. The strategy can actively transport drugs, such as small molecular drugs, gene medicines, and therapeutic proteins to glioma while minimizing adverse reactions. This review will summarize recent progress on receptor-mediated drug delivery systems targeting to glioma, and conclude the challenges and prospects of receptor-mediated glioma-targeted therapy for future applications.

  2. Diversity and severity of adverse reactions to quinine: A systematic review.

    Science.gov (United States)

    Liles, Nathan W; Page, Evaren E; Liles, Amber L; Vesely, Sara K; Raskob, Gary E; George, James N

    2016-05-01

    Quinine is a common cause of drug-induced thrombocytopenia and the most common cause of drug-induced thrombotic microangiopathy. Other quinine-induced systemic disorders have been described. To understand the complete clinical spectrum of adverse reactions to quinine we searched 11 databases for articles that provided sufficient data to allow evaluation of levels of evidence supporting a causal association with quinine. Three reviewers independently determined the levels of evidence, including both immune-mediated and toxic adverse reactions. The principal focus of this review was on acute, immune-mediated reactions. The source of quinine exposure, the involved organ systems, the severity of the adverse reactions, and patient outcomes were documented. One hundred-fourteen articles described 142 patients with definite or probable evidence for a causal association of quinine with acute, immune-mediated reactions. These reactions included chills, fever, hypotension, painful acral cyanosis, disseminated intravascular coagulation, hemolytic anemia, thrombocytopenia, neutropenia, acute kidney injury, rhabdomyolysis, liver toxicity, cardiac ischemia, respiratory failure, hypoglycemia, blindness, and toxic epidermal necrolysis. One hundred-two (72%) reactions were caused by quinine pills; 28 (20%) by quinine-containing beverages; 12 (8%) by five other types of exposures. Excluding 41 patients who had only dermatologic reactions, 92 (91%) of 101 patients had required hospitalization for severe illness; 30 required renal replacement therapy; three died. Quinine, even with only minute exposure from common beverages, can cause severe adverse reactions involving multiple organ systems. In patients with acute, multi-system disorders of unknown origin, an adverse reaction to quinine should be considered.

  3. Transgenic expression of green fluorescent protein in caprine embryos produced through electroporation-aided sperm-mediated gene transfer.

    Science.gov (United States)

    Kumar Pramod, R; Kumar, Rakesh; Mitra, Abhijit

    2016-01-15

    Current methods of transgenic animal production are afflicted by low efficiency and high cost. Recently, the electroporation aided sperm-mediated gene transfer (SMGT) emerges as a promising alternative with variable success rate. Among the domestic animal species, the electroporation-aided SMGT is less investigated in goats, except a few reports in which attempts have been made using the auto-uptake method of SMGT. In this study, we report an optimized electroporation condition for SMGT of caprine sperm cells. Results of this study demonstrated that electroporation of caprine sperm cells at 300 V for 200 mS in TALP medium allowed the maximum uptake of foreign DNA with minimum adverse effects on the vital semen parameters viz., progressive motility, viability, and membrane and acrosome integrity. Further, DNA binding assay revealed DNA uptake by 81.3% sperm cells when 1.0 μg of DNA was used under optimum electroporation conditions as compared to 16.5% on simple incubation. The qPCR analysis showed four-fold more (Pelectroporation than incubation. A similar cleavage rate was observed after IVF using either electroporated (23.20 ± 1.20) or non-electroporated (25.20 ± 2.41) sperm cells suggesting the absence of adverse effect of electroporation on the fertilizing ability. Out of the 116 embryos produced by electroporated sperm, five (4.31%) embryos showed the expression of the foreign gene. In conclusion, our results confirm that using optimized electroporation conditions, the caprine sperm cells can uptake foreign DNA effectively with minimum negative effect on the semen parameters and could produce transgenic embryos.

  4. Eikonal reaction theory for two-neutron removal reactions

    CERN Document Server

    Minomo, K; Egashira, K; Ogata, K; Yahiro, M

    2014-01-01

    The eikonal reaction theory (ERT) proposed lately is a method of calculating one-neutron removal reactions at intermediate incident energies in which Coulomb breakup is treated accurately with the continuum discretized coupled-channels method. ERT is extended to two-neutron removal reactions. ERT reproduces measured one- and two-neutron removal cross sections for 6He scattering on 12C and 208Pb targets at 240 MeV/nucleon and also on a 28Si target at 52 MeV/nucleon. For the heavier target in which Coulomb breakup is important, ERT yields much better agreement with the measured cross sections than the Glauber model.

  5. Mediating Trust in Terrorism Coverage

    DEFF Research Database (Denmark)

    Mogensen, Kirsten

    crisis. While the framework is presented in the context of television coverage of a terror-related crisis situation, it can equally be used in connection with all other forms of mediated trust. Key words: National crisis, risk communication, crisis management, television coverage, mediated trust.......Mass mediated risk communication can contribute to perceptions of threats and fear of “others” and/or to perceptions of trust in fellow citizens and society to overcome problems. This paper outlines a cross-disciplinary holistic framework for research in mediated trust building during an acute...

  6. When Memories are Mediated

    DEFF Research Database (Denmark)

    Frølunde, Lisbeth; Bjerregaard, Mette

    2013-01-01

    and political contexts and media platforms take place and become contexts for audience reception. This paper explores two examples of narratives that construct memories of acts of mass violence: “Gzim Rewind” (Sweden, 2011, director Knutte Wester) about 1990’s Kosovo, and “The Act of Killing” (Denmark, 2012......Acts of mass violence, including murder on civilians, genocide, oppression and wars, can mobilize memories of the involved persons and following generations in a certain historical situation. Acts of mass violence can also create a sort of looking glass of culturally dominant memories...... that are mediated through stories: told and retold as oral stories through generations, as myths or sagas, or remediated as contemporary documentary film accounts or more fictional film accounts. In these processes of retelling acts of violence, transformations of meanings across time, cultural, social...

  7. Neutrino assisted gauge mediation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Do; Mo, Doh Young; Seo, Min-Seok [Seoul National University, Department of Physics and Astronomy and Center for Theoretical Physics, Seoul (Korea, Republic of)

    2013-06-15

    Recent observation shows that the Higgs mass is at around 125 GeV while the prediction of the minimal supersymmetric standard model is below 120 GeV for stop mass lighter than 2 TeV unless the top squark has a maximal mixing. We consider the right-handed neutrino supermultiplets as messengers in addition to the usual gauge mediation to obtain sizeable trilinear soft parameters A{sub t} needed for the maximal stop mixing. Neutrino messengers can explain the observed Higgs mass for stop mass around 1 TeV. Neutrino assistance can also generate charged lepton flavor violation including {mu}{yields}e {gamma} as a possible signature of the neutrino messengers. We consider the S{sub 4} discrete flavor model and show the relation of the charged lepton flavor violation, {theta} {sub 13} of neutrino oscillation and the muon's g-2. (orig.)

  8. Novel Methodology for Rapid Detection of KRAS Mutation Using PNA-LNA Mediated Loop-Mediated Isothermal Amplification.

    Directory of Open Access Journals (Sweden)

    Masahiro Itonaga

    Full Text Available Detecting point mutation of human cancer cells quickly and accurately is gaining in importance for pathological diagnosis and choice of therapeutic approach. In the present study, we present novel methodology, peptide nucleic acid-locked nucleic acid mediated loop-mediated isothermal amplification (PNA-LNA mediated LAMP, for rapid detection of KRAS mutation using advantages of both artificial DNA and LAMP. PNA-LNA mediated LAMP reactions occurred under isothermal temperature conditions of with 4 primary primers set for the target regions on the KRAS gene, clamping PNA probe that was complimentary to the wild type sequence and LNA primers complementary to the mutated sequences. PNA-LNA mediated LAMP was applied for cDNA from 4 kinds of pancreatic carcinoma cell lines with or without KRAS point mutation. The amplified DNA products were verified by naked-eye as well as a real-time PCR equipment. By PNA-LNA mediated LAMP, amplification of wild type KRAS DNA was blocked by clamping PNA probe, whereas, mutant type KRAS DNA was significantly amplified within 50 min. Mutant alleles could be detected in samples which diluted until 0.1% of mutant-to-wild type ratio. On the other hand, mutant alleles could be reproducibly with a mutant-to-wild type ratio of 30% by direct sequencing and of 1% by PNA-clamping PCR. The limit of detection (LOD of PNA-LNA mediated LAMP was much lower than the other conventional methods. Competition of LNA clamping primers complementary to two different subtypes (G12D and G12V of mutant KRAS gene indicated different amplification time depend on subtypes of mutant cDNA. PNA-LNA mediated LAMP is a simple, rapid, specific and sensitive methodology for the detection of KRAS mutation.

  9. Catalytic Organic Transformations Mediated by Actinide Complexes

    Directory of Open Access Journals (Sweden)

    Isabell S. R. Karmel

    2015-10-01

    Full Text Available This review article presents the development of organoactinides and actinide coordination complexes as catalysts for homogeneous organic transformations. This chapter introduces the basic principles of actinide catalysis and deals with the historic development of actinide complexes in catalytic processes. The application of organoactinides in homogeneous catalysis is exemplified in the hydroelementation reactions, such as the hydroamination, hydrosilylation, hydroalkoxylation and hydrothiolation of alkynes. Additionally, the use of actinide coordination complexes for the catalytic polymerization of α-olefins and the ring opening polymerization of cyclic esters is presented. The last part of this review article highlights novel catalytic transformations mediated by actinide compounds and gives an outlook to the further potential of this field.

  10. Investigation of drugs responsible for perioperative anaphylactic reactions using cellular allergen stimulation test

    Institute of Scientific and Technical Information of China (English)

    Xin Xin; Zou Yi; Xing Lijiao; Yin Jia; Gu Jianqing; Wang Zixi; Huang Yuguang

    2014-01-01

    Background Anaphylactic reactions during anesthesia and operation are common and life threatening.Follow-up investigation is necessary for avoiding potential re-exposure of the patients to the offending drugs.The purpose of this study was to assess cellular allergen stimulation test (CAST) as a diagnostic instrument in immunoglobulin E (IgE)-and non-lgE-mediated anaphylactic reactions.Methods This study included 25 patients who developed perioperative anaphylactic reactions and 10 subjects that tolerated anesthetics and other drugs during perioperative period from September 2009 to October 2013 in Peking Union Medical College Hospital.We performed skin tests and flow cytometric analysis of basophil activation-based CAST in all subjects.Results Of the 25 patients,17 had IgE-mediated anaphylactic reactions (causative agent identified by skin tests) and 8 had non-lgE-mediated anaphylactic reactions (negative skin tests).CAST showed a sensitivity of 42.9%,specificity of 90%,and negative predictive value of 80.6% for neuromuscular blocking agents.Conclusions CAST may be useful for the diagnosis of anaphylactic reactions during perioperative period.Our findings call for further investigation to increase the sensitivity of the test.

  11. Prostaglandin modulation of mouse and human sperm capacitation.

    Science.gov (United States)

    Herrero, M B; Viggiano, J M; Boquet, M; Gimeno, M A

    1997-09-01

    To determine whether prostaglandins produce a capacitation and/or acrosome reaction, the effect of prostaglandins on capacitated mouse spermatozoa and the effect of prostaglandin pre-incubation on human and mouse spermatozoa were studied. Prostaglandins did not induce an acrosome reaction in capacitated mouse sperm. PGE1 pre-incubation in a protein-free medium enhanced acrosome loss of mouse sperm challenged with A-23187 or solubilized mouse zona pellucida. Human sperm were pre-incubated in media containing prostaglandins, and an acrosome reaction was induced with calcium ionophore or human follicular fluid. PGE1 pre-incubation enhanced acrosome loss by human sperm when the action was induced with calcium ionophore, but had no effect on follicular fluid induction. We conclude that PGE1 acts as a capacitating factor in vitro for mouse spermatozoa, and enhances acrosome-reaction induction with calcium ionophore in human spermatozoa.

  12. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    Science.gov (United States)

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc.

  13. On the Reaction Path Hamiltonian

    Institute of Scientific and Technical Information of China (English)

    孙家钟; 李泽生

    1994-01-01

    A vector-fiber bundle structure of the reaction path Hamiltonian, which has been introduced by Miller, Handy and Adams, is explored with respect to molecular vibrations orthogonal to the reaction path. The symmetry of the fiber bundle is characterized by the real orthogonal group O(3N- 7) for the dynamical system with N atoms. Under the action of group O(3N- 7). the kinetic energy of the reaction path Hamiltonian is left invariant. Furthermore , the invariant behaviour of the Hamiltonian vector fields is investigated.

  14. Palladium-catalyzed coupling reactions

    CERN Document Server

    Molnár, Árpád

    2013-01-01

    This handbook and ready reference brings together all significant issues of practical importance for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of modern-day coupling reactions and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With i

  15. Nuclear reactions at intermediate energies

    Directory of Open Access Journals (Sweden)

    Shyam Radhey

    2016-01-01

    Full Text Available In the domain of Nuclear reactions at intermediate energies, the QCD coupling constant αs is large enough (~ 0.3 - 0.5 to render the perturbative calculational techniques inapplicable. In this regime the quarks are confined into colorless hadrons and it is expected that effective field theories of hadron interactions via exchange of hadrons, provide useful tools to describe such reactions. In this contribution we discuss the application of one such theory, the effective Lagrangian model, in describing the hadronic reactions at intermediate energies whose measurements are the focus of a vast international experimental program.

  16. The mediation procedure in Romania

    Directory of Open Access Journals (Sweden)

    Alexandrina Zaharia

    2009-06-01

    Full Text Available The mediation activity as an alternative way of solving conflicts occupies an important place in modernsociety. Currently, the mediation reached its maturity worldwide being adopted without reservations.The future of solving conflicts is undoubtedly closely related to mediation. XXth century is the century of solvingconflicts amiably outside the court room. In Romania and the mediation profession were regulated by the Law no.192/2006, on the basis of the idea that mediation is one of the major themes of the reform strategy of the judicialsystem 2005-2007. By adopting the mentioned law it was followed the idea of reducing the volume of activitycourts, and therefore, relieve them of as many cases, with the direct effect on the quality of justice. Mediation is avoluntary process in which the parties with a neutral and impartial third party, without power of decision - themediator - who is qualified to assist the parties to negotiate, facilitating the communication between them andhelping them to reach a unanimous effective and sustainable agreement. The parties may resort to mediation beforeor after triggering a trial. Mediation can be applied, in principle, on any type of conflict. However, theRomanian legislator has established special stipulations on conflict mediation in criminal, civil and familylaw. Although not expressly provided, the stipulations regarding the civil conflicts and also apply to commercialconflicts. Therefore, the mediation is applicable to most types of lawsuits, except those relating to personalrights. As a "win- win" principle, the mediation does not convert any of the parties defeated or victorious; allthose involved have gained by applying this procedure.

  17. A 17 year experience in perioperative anaphylaxis 1998-2015: harmonising optimal detection of mast cell mediator release.

    OpenAIRE

    Egner, W.; Sargur, R.; Shrimpton, A.; York, M.; Green, K

    2016-01-01

    BACKGROUND: Sheffield NARCOS (National Adverse Reactions Advisory Service) investigates suspected perioperative anaesthetic reactions using serial tryptase, urinary methylhistamine and clinical information. Further recommendations for additional allergy clinic assessment are provided. OBJECTIVE: To establish a robustly measurable protocol for identifying mast cell mediator (MMR) release in this cohort. To compare these thresholds with previous suggested thresholds and algorithms. METHOD: A re...

  18. Silver-mediated decarboxylative C-S cross-coupling of aliphatic carboxylic acids under mild conditions.

    Science.gov (United States)

    Wang, Peng-Fei; Wang, Xiao-Qing; Dai, Jian-Jun; Feng, Yi-Si; Xu, Hua-Jian

    2014-09-05

    A silver-mediated decarboxylative C-S cross-coupling reaction of aliphatic carboxylic acid is described. This reaction occurs smoothly under mild conditions and shows good tolerance of functional groups. It provides an alternative approach for the synthesis of alkyl aryl sulfides.

  19. Histone chaperone-mediated nucleosome assembly process.

    Science.gov (United States)

    Fan, Hsiu-Fang; Liu, Zi-Ning; Chow, Sih-Yao; Lu, Yi-Han; Li, Hsin

    2015-01-01

    A huge amount of information is stored in genomic DNA and this stored information resides inside the nucleus with the aid of chromosomal condensation factors. It has been reported that the repeat nucleosome core particle (NCP) consists of 147-bp of DNA and two copies of H2A, H2B, H3 and H4. Regulation of chromosomal structure is important to many processes inside the cell. In vivo, a group of histone chaperones facilitate and regulate nucleosome assembly. How NCPs are constructed with the aid of histone chaperones remains unclear. In this study, the histone chaperone-mediated nucleosome assembly process was investigated using single-molecule tethered particle motion (TPM) experiments. It was found that Asf1 is able to exert more influence than Nap1 and poly glutamate acid (PGA) on the nucleosome formation process, which highlights Asf1's specific role in tetrasome formation. Thermodynamic parameters supported a model whereby energetically favored nucleosomal complexes compete with non-nucleosomal complexes. In addition, our kinetic findings propose the model that histone chaperones mediate nucleosome assembly along a path that leads to enthalpy-favored products with free histones as reaction substrates.

  20. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.