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Sample records for puva inhibits degranulation

  1. Effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells. II. In vitro PUVA inhibits degranulation of rat peritoneal mast cells induced by compound 48/80

    SciTech Connect

    Toda, K.; Danno, K.; Tachibana, T.; Horio, T.

    1986-07-01

    Rat peritoneal mast cells incubated with a histamine liberator, compound 48/80, showed a significantly reduced capacity for releasing histamine following in vitro treatment with 0.1 micrograms/ml of 8-methoxypsoralen (8-MOP) plus 1-5 J/cm2 of long-wave ultraviolet (UVA) irradiation (PUVA). No remarkable inhibition in histamine release was observed in the cells treated with 8-MOP only. Irradiation with 5 J/cm2 of UVA alone exerted an inhibitory effect on histamine release, to a lesser extent than PUVA. PUVA irradiation did not bring any decrease in cell viability or any spontaneous release of histamine from irradiated cells as shown by phase-contrast microscopy and by histamine assay, respectively. These results suggest that PUVA treatment may cause a noncytotoxic disturbance at mast cell membranes or on surface receptors, leading to a decreased capacity for secreting chemical mediators.

  2. Effect of 8-methoxypsoralen plus long-wave ultraviolet (PUVA) radiation on mast cells: PUVA suppresses degranulation of mouse skin mast cells induced by compound 48/80 or concanavalin A

    SciTech Connect

    Danno, K.; Toda, K.; Horio, T.

    1985-08-01

    Ears of mice were treated with a 0.5% 8-MOP solution topically plus UVA radiation (1.5-2.5 J/cm2). After PUVA radiation, skin responses to intradermal injection with mast cell liberators, including compound 48/80 (2.5 mg/ml, 10 microliter) and concanavalin A (Con-A) (2.0 mg/ml), or with a mixture of 5-hydroxytryptamine (5-HT) and histamine as vasodilator (1.0 mg/ml and 50 mM, respectively) were examined with time (2 h-14 days). At each time point, an ear swelling response (ESR) was measured with a dial thickness gauge. The rate of mast cell degranulation and mast cell numbers were assessed by light microscopy using toluidine blue-stained semithin (1 micron) sections. ESR induced by compound 48/80 or Con-A was significantly suppressed dose-dependently (greater than 42% inhibition) by PUVA between 2 h-3 days postirradiation as compared with that in nonirradiated control mice, and the value returned to normal levels by 7-14 days. Compound 48/80- or Con-A-induced mast cell degranulation (%) was remarkably decreased between 2 h-3 days (greater than 48% inhibition) in accordance with the suppression in ESR and it was restored to the rates in nonirradiated controls by 7-14 days. Neither ESR nor percent degranulation was affected by UVA radiation only (less than 3.5 J/cm2) or application of 8-MOP only. 5-HT plus histamine-mediated ESR was not altered at all by PUVA throughout the experimental period. Since PUVA radiation itself at given doses did not produce measurable ESR, mast cell degranulation, or a reduction in mast cell numbers, and since PUVA did not affect a normal vascular response to vasodilator, it seemed that decreased skin reactivity to mast cell degranulators by PUVA might be due to a PUVA-induced noncytolytic alteration in mast cell release mechanisms.

  3. Arsenic inhibits mast cell degranulation via suppression of early tyrosine phosphorylation events.

    PubMed

    Shim, Juyoung; Kennedy, Rachel H; Weatherly, Lisa M; Hutchinson, Lee M; Pelletier, Jonathan H; Hashmi, Hina N; Blais, Kayla; Velez, Alejandro; Gosse, Julie A

    2016-11-01

    Exposure to arsenic is a global health concern. We previously documented an inhibitory effect of inorganic Arsenite on IgE-mediated degranulation of RBL-2H3 mast cells (Hutchinson et al., 2011; J. Appl. Toxicol. 31: 231-241). Mast cells are tissue-resident cells that are positioned at the host-environment interface, thereby serving vital roles in many physiological processes and disease states, in addition to their well-known roles in allergy and asthma. Upon activation, mast cells secrete several mediators from cytoplasmic granules, in degranulation. The present study is an investigation of Arsenite's molecular target(s) in the degranulation pathway. Here, we report that arsenic does not affect degranulation stimulated by either the Ca(2) (+) ionophore A23187 or thapsigargin, which both bypass early signaling events. Arsenic also does not alter degranulation initiated by another non-IgE-mediated mast cell stimulant, the G-protein activator compound 48/80. However, arsenic inhibits Ca(2) (+) influx into antigen-activated mast cells. These results indicate that the target of arsenic in the degranulation pathway is upstream of the Ca(2) (+) influx. Phospho-Syk and phospho-p85 phosphoinositide 3-kinase enzyme-linked immunosorbent assays data show that arsenic inhibits early phosphorylation events. Taken together, this evidence indicates that the mechanism underlying arsenic inhibition of mast cell degranulation occurs at the early tyrosine phosphorylation steps in the degranulation pathway. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Fluvastatin inhibits mast cell degranulation without changing the cytoplasmic Ca2+ level.

    PubMed

    Fujimoto, Masanori; Oka, Tatsuya; Murata, Takahisa; Hori, Masatoshi; Ozaki, Hiroshi

    2009-01-14

    We evaluated the pharmacological effect of statins (3-hydroxy-3-methylglutaryl-CoA reductase inhibitors) on mast cell degranulation in RBL-2H3 cells. A hydrophilic statin (pravastatin) did not inhibit degranulation induced by dinitrophenol-human serum albumin (DNP-HSA); in contrast, lipophilic statins (simvastatin, fluvastatin and atorvastatin) inhibited DNP-HSA-induced degranulation in that order. The inhibitory effects were completely attenuated by simultaneous treatment with 100-1000 microM mevalonic acid for 4 h. We used fluvastatin to clarify the mechanism of the statin-mediated inhibitory action of mast cell degranulation. Fluvastatin (3 microM) had no effect on Ca(2+) release from the endoplasmic reticulum or Ca(2+) influx in the DNP-HSA- or thapsigargin-stimulated cells. Fluvastatin treatment also had no effect on the total granule content of the cell or sensitivity to DNP-HSA and IgE. Fluvastatin (3 microM, 24 h treatment) also failed to affect the morphology, proliferation, and viability of RBL-2H3 cells. Geranylgeranyl transferase inhibitor, GGTI-286 (20 microM), but not farnesyl transferase inhibitor, FPTIII (20 microM), inhibited the DNP-HSA-induced degranulation. The GGTI-286-induced inhibitory action was not associated with a decrease in the cytoplasmic Ca(2+) level. In conclusion, fluvastatin at a lower concentration range inhibited DNP-HSA-induced degranulation without affecting the cytoplasmic Ca(2+) response and also without changing the amount of granule content and proliferation of the mast cells. The statin-induced inhibitory action may be mediated by the suppression of geranylgeranyl transferase via the depletion of intracellular mevalonic acid.

  5. Protein kinase C activation inhibits eosinophil degranulation through stimulation of intracellular cAMP production.

    PubMed

    Ezeamuzie, Charles I; Taslim, Najla

    2004-11-01

    The mechanism of inhibition of eosinophil degranulation by protein kinase C (PKC) was investigated in complement C5a (C5a)-stimulated degranulation of highly purified human eosinophils using the specific PKC activator - phorbol 12-myristate 13-acetate (PMA). C5a-induced release of eosinophil peroxidase and eosinophil cationic protein was potently inhibited in a concentration-dependent manner by PMA (IC(50): 3 and 5 nM, respectively). The inhibition by PMA, but not histamine, was significantly reversed by the specific, but isoform nonselective, PKC inhibitor Ro 31-8220 (1 microM). In the presence of phosphodiesterase inhibitor rolipram (5 microM), PMA stimulated a pronounced concentration-dependent increase in intracellular cAMP, with a potency 400 times that of histamine (EC(50): 55 nM vs 22.5 microM). The inactive PMA analogue, 4alpha-PMA, had no such effect. The cAMP production by PMA, but not histamine, was significantly reversed by Ro 31-8220 (1 microM) and the selective inhibitor of the novel PKCdelta, rottlerin (1-3 microM), but not the selective inhibitor of the classical PKC isoforms, Gö 6976 (0.01-0.1 microM). Western blot analysis revealed the presence of six PKC isoforms (alpha, betaI, betaII, delta, iota and zeta) in isolated eosinophils. Chelation of internal or external calcium had no effect on PMA-induced cAMP response, but abolished that induced by histamine. There was a good correlation between increase in intracellular cAMP and inhibition of degranulation. These results show, for the first time, that in human eosinophils, PMA, via activation of PKCdelta isoform, can stimulate cAMP production, and that this may be the basis for its potent anti-degranulatory effect.

  6. Protein kinase C activation inhibits eosinophil degranulation through stimulation of intracellular cAMP production

    PubMed Central

    Ezeamuzie, Charles I; Taslim, Najla

    2004-01-01

    The mechanism of inhibition of eosinophil degranulation by protein kinase C (PKC) was investigated in complement C5a (C5a)-stimulated degranulation of highly purified human eosinophils using the specific PKC activator – phorbol 12-myristate 13-acetate (PMA). C5a-induced release of eosinophil peroxidase and eosinophil cationic protein was potently inhibited in a concentration-dependent manner by PMA (IC50: 3 and 5 nM, respectively). The inhibition by PMA, but not histamine, was significantly reversed by the specific, but isoform nonselective, PKC inhibitor Ro 31-8220 (1 μM). In the presence of phosphodiesterase inhibitor rolipram (5 μM), PMA stimulated a pronounced concentration-dependent increase in intracellular cAMP, with a potency 400 times that of histamine (EC50: 55 nM vs 22.5 μM). The inactive PMA analogue, 4α-PMA, had no such effect. The cAMP production by PMA, but not histamine, was significantly reversed by Ro 31-8220 (1 μM) and the selective inhibitor of the novel PKCδ, rottlerin (1–3 μM), but not the selective inhibitor of the classical PKC isoforms, Gö 6976 (0.01–0.1 μM). Western blot analysis revealed the presence of six PKC isoforms (α, βI, βII, δ, ι and ζ) in isolated eosinophils. Chelation of internal or external calcium had no effect on PMA-induced cAMP response, but abolished that induced by histamine. There was a good correlation between increase in intracellular cAMP and inhibition of degranulation. These results show, for the first time, that in human eosinophils, PMA, via activation of PKCδ isoform, can stimulate cAMP production, and that this may be the basis for its potent anti-degranulatory effect. PMID:15504748

  7. Gangliosides inhibit bee venom melittin cytotoxicity but not phospholipase A{sub 2}-induced degranulation in mast cells

    SciTech Connect

    Nishikawa, Hirofumi; Kitani, Seiichi

    2011-05-01

    Sting accident by honeybee causes severe pain, inflammation and allergic reaction through IgE-mediated anaphylaxis. In addition to this hypersensitivity, an anaphylactoid reaction occurs by toxic effects even in a non-allergic person via cytolysis followed by similar clinical manifestations. Auto-injectable epinephrine might be effective for bee stings, but cannot inhibit mast cell lysis and degranulation by venom toxins. We used connective tissue type canine mast cell line (CM-MC) for finding an effective measure that might inhibit bee venom toxicity. We evaluated degranulation and cytotoxicity by measurement of {beta}-hexosaminidase release and MTT assay. Melittin and crude bee venom induced the degranulation and cytotoxicity, which were strongly inhibited by mono-sialoganglioside (G{sub M1}), di-sialoganglioside (G{sub D1a}) and tri-sialoganglioside (G{sub T1b}). In contrast, honeybee venom-derived phospholipase A{sub 2} induced the net degranulation directly without cytotoxicity, which was not inhibited by G{sub M1}, G{sub D1a} and G{sub T1b}. For analysis of distribution of G{alpha}{sub q} and G{alpha}{sub i} protein by western blotting, lipid rafts were isolated by using discontinuous sucrose gradient centrifuge. Melittin disrupted the localization of G{alpha}{sub q} and G{alpha}{sub i} at lipid raft, but gangliosides stabilized the rafts. As a result from this cell-based study, bee venom-induced anaphylactoid reaction can be explained with melittin cytotoxicity and phospholipase A{sub 2}-induced degranulation. Taken together, gangliosides inhibit the effect of melittin such as degranulation, cytotoxicity and lipid raft disruption but not phospholipase A{sub 2}-induced degranulation in mast cells. Our study shows a potential of gangliosides as a therapeutic tool for anaphylactoid reaction by honeybee sting.

  8. Suppression of Brain Mast Cells Degranulation Inhibits Microglial Activation and Central Nervous System Inflammation.

    PubMed

    Dong, Hongquan; Zhang, Xiang; Wang, Yiming; Zhou, Xiqiao; Qian, Yanning; Zhang, Shu

    2017-03-01

    Brain inflammation has a critical role in the pathophysiology of brain diseases. Microglia, the resident immune cells in the brain, play an important role in brain inflammation, while brain mast cells are the "first responder" in the injury rather than microglia. Functional aspects of mast cell-microglia interactions remain poorly understood. Our results demonstrated that site-directed injection of the "mast cell degranulator" compound 48/80 (C48/80) in the hypothalamus induced mast cell degranulation, microglial activation, and inflammatory factor production, which initiated the acute brain inflammatory response. "Mast cell stabilizer" disodium cromoglycate (cromolyn) inhibited this effect, including decrease of inflammatory cytokines, reduced microglial activation, inhibition of MAPK and AKT pathways, and repression of protein expression of histamine receptor 1 (H1R), histamine receptor 4 (H4R), protease-activated receptor 2 (PAR2), and toll-like receptor 4 (TLR4) in microglia. We also demonstrated that C48/80 had no effect on microglial activation in mast cell-deficient Kit(W-sh/W-sh) mice. These results implicate that activated brain mast cells trigger microglial activation and stabilization of mast cell inhibits microglial activation-induced central nervous system (CNS) inflammation. Interactions between mast cells and microglia could constitute a new and unique therapeutic target for CNS immune inflammation-related diseases.

  9. Degranulation of mast cells and inhibition of the response to secretory agents by phototoxic compounds and ultraviolet radiation

    SciTech Connect

    Gendimenico, G.J.; Kochevar, I.E.

    1984-11-01

    The symptoms of cutaneous phototoxicity from coal tar compounds and the nonsteroidal anti-inflammatory drug benoxaprofen are characterized by wheal and flare formation which is mediated by histamine released from dermal mast cells. Rat serosal mast cells were used as an in vitro model system to study the direct effect of phototoxic compounds on mast cell degranulation. The coal tar compounds studied included acridine and pyrene. Combined exposure of cells to acridine and UVA (320 to 400 nm) radiation caused mast cells to degranulate, as assayed by the release of (/sup 3/H)serotonin. Maximum (/sup 3/H)serotonin release (70 to 80%) was obtained with 50 microM acridine and 300 kJ/m2 UVA. Pyrene (25 microM), when photoexcited with UVB (280 to 360 nm) radiation, caused about 80% release of (/sup 3/H)serotonin. No degranulation occurred with 20 microM benoxaprofen and UVB doses up to 7.2 kJ/m2. Trypan blue staining correlated well with degranulation caused by acridine plus UVA; however, with pyrene plus UVB there was greater (/sup 3/H)serotonin release than dye uptake. Excitation of photosensitizers with doses of UV radiation that did not cause trypan blue staining suppressed degranulation of mast cells in response to chemical stimulation. Acridine, pyrene, and benoxaprofen in the presence of UV radiation inhibited the mast cells from responding to compound 48/80 or the calcium ionophore, chlortetracycline. Two other phototoxic compounds, chlorpromazine and deoxytetracycline, also abolished degranulation by compound 48/80. These findings indicate that phototoxic compounds: (1) cause degranulation in the presence of high doses of UV radiation; and (2) suppress degranulation of mast cells in response to secretory stimuli at doses of UV radiation that do not cause release of mediator.

  10. Toxoplasma gondii inhibits mast cell degranulation by suppressing phospholipase Cγ-mediated Ca2+ mobilization

    PubMed Central

    Smith, Norah L.; Abi Abdallah, Delbert S.; Butcher, Barbara A.; Denkers, Eric Y.; Baird, Barbara; Holowka, David

    2013-01-01

    Toxoplasma gondii is well-known to subvert normal immune responses, however, mechanisms are incompletely understood. In particular, its capacity to alter receptor-activated Ca2+-mediated signaling processes has not been well-characterized. In initial experiments, we found evidence that T. gondii infection inhibits Ca2+ responses to fMetLeuPhe in murine macrophages. To further characterize the mechanism of inhibition of Ca2+ mobilization by T. gondii, we used the well-studied RBL mast cell model to probe the capacity of T. gondii to modulate IgE receptor-activated signaling within the first hour of infection. Ca2+ mobilization that occurs via IgE/FcεRI signaling leads to granule exocytosis in mast cells. We found that T. gondii inhibits antigen-stimulated degranulation in infected cells in a strain-independent manner. Under these conditions, we found that cytoplasmic Ca2+ mobilization, particularly antigen-mediated Ca2+ release from intracellular stores, is significantly reduced. Furthermore, stimulation-dependent activation of Syk kinase leading to tyrosine phosphorylation and activation of phospholipase Cγ is inhibited by infection. Therefore, we conclude that inhibitory effects of infection are likely due to parasite-mediated inhibition of the tyrosine kinase signaling cascade that results in reduced hydrolysis of phosphatidylinositol 4,5-bisphosphate. Interestingly, inhibition of IgE/FcεRI signaling persists when tachyzoite invasion is arrested via cytochalasin D treatment, suggesting inhibition is mediated by a parasite-derived factor secreted into the cells during the invasion process. Our study provides direct evidence that immune subversion by T. gondii is initiated concurrently with invasion. PMID:23847603

  11. Systemic Effects of Ingested Lactobacillus Rhamnosus: Inhibition of Mast Cell Membrane Potassium (IKCa) Current and Degranulation

    PubMed Central

    Forsythe, Paul; Wang, Binxiang; Khambati, Ibrahim; Kunze, Wolfgang A.

    2012-01-01

    Exposure of the intestine to certain strains lactobacillus can have systemic immune effects that include the attenuation of allergic responses. Despite the central role of mast cells in allergic disease little is known about the effect of lactobacilli on the function of these cells. To address this we assessed changes in rat mast cell activation following oral treatment with a strain of Lactobacillus known to attenuate allergic responses in animal models. Sprague Dawley rats were fed with L.rhamnosus JB-1 (1×109) or vehicle control for 9 days. Mediator release from peritoneal mast cells (RPMC) was determined in response to a range of stimuli. Passive cutaneous anaphylaxis (PCA) was used to assess mast cell responses in vivo. The Ca2+ activated K+ channel (KCa3.1) current, identified as critical to mast cell degranulation, was monitored by whole cell patch-clamp. L.rhamnosus JB-1 treatment lead to significant inhibition of mast cell mediator release in response to a range of stimuli including IgE mediated activation. Furthermore, the PCA response was significantly reduced in treated rats. Patch-clamp studies revealed that RPMC from treated animals were much less responsive to the KCa3.1 opener, DCEBIO. These studies demonstrate that Ingestion of L.rhamnosus JB-1 leads to mast cell stabilization in rats and identify KCa3.1 as an immunomodulatory target for certain lactobacilli. Thus the systemic effects of certain candidate probiotics may include mast cell stabilization and such actions could contribute to the beneficial effect of these organisms in allergic and other inflammatory disorders. PMID:22815978

  12. The antinociception of oxytocin on colonic hypersensitivity in rats was mediated by inhibition of mast cell degranulation via Ca2+-NOS pathway

    PubMed Central

    Gong, Liping; Li, Jing; Tang, Yan; Han, Ting; Wei, Chuanfei; Yu, Xiao; Li, Jingxin; Wang, Rong; Ma, Xuelian; Liu, Kejing; Geng, Lingyun; Liu, Shaozhuang; Yan, Bing; Liu, Chuanyong

    2016-01-01

    This study was conducted to investigate the effects of oxytocin (OT) on visceral hypersensitivity/pain and mast cell degranulation and the underlying mechanisms. We found that oxytocin receptor (OTR) was expressed in colonic mast cells in humans and rats, as well as in human mast cell line-1 (HMC-1), rat basophilic leukemia cell line (RBL-2H3) and mouse mastocytoma cell line (P815). OT decreased 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced visceral hypersensitivity, colonic mast cell degranulation and histamine release after mast cell degranulation in rats. Also, OT attenuated the compound 48/80 (C48/80)-evoked histamine release in P815 cells and inward currents, responsible for the mast cell degranulation, in HMC-1, RBL-2H3 and P815 cells. Moreover, these protective effects of OT against visceral hypersensitivity and mast cell degranulation were eliminated by coadministration of OTR antagonist atosiban or a nonselective inhibitor of nitric oxide synthase (NOS), NG-Methyl-L-arginine acetate salt (L-NMMA). Notably, OT evoked a concentration-dependent increase of intracellular Ca2+ in HMC-1, RBL-2H3 and P815 cells, which was responsible for the activation of neuronal NOS (NOS1) and endothelial NOS (NOS3). Our findings strongly suggest that OT might exert the antinociception on colonic hypersensitivity through inhibition of mast cell degranulation via Ca2+-NOS pathway. PMID:27538454

  13. Ethanol Extract of Sanguisorbae Radix Inhibits Mast Cell Degranulation and Suppresses 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis-Like Skin Lesions

    PubMed Central

    Yang, Ju-Hye; Yoo, Jae-Myung; Cho, Won-Kyung; Ma, Jin Yeul

    2016-01-01

    Sanguisorbae Radix (SR) is well known as herbal medicine named “Zi-Yu” in Korea, which is the dried roots of Sanguisorba officinalis L. (Rosacease). We investigated the underlying mechanism on the inhibition of atopic dermatitis (AD) of an ethanol extract of SR (ESR) using 2,4-dinitrochlorobenzene- (DNCB-) induced AD mice model. Oral administration of ESR significantly suppressed DNCB-induced AD-like symptoms such as scratching behavior, ear thickness, epidermal thickness, and IgE levels. To investigate the effects of ESR treatment on degranulation of IgE/Ag-activated mouse bone marrow-derived mast cells (BMMCs), we measured the release of β-hexosaminidase (β-HEX, degranulation marker). ESR decreased the infiltration of eosinophils and mast cells into the AD skin lesions. Furthermore, ESR significantly inhibited degranulation of IgE/Ag-activated BMMCs. We have demonstrated that ESR decreased AD symptoms in mice and inhibits degranulation of IgE/Ag-activated mast cells. Our study suggests that ESR may serve as a potential therapeutic candidate for the treatment of AD symptoms. PMID:27065570

  14. Simultaneous initiation of degranulation and inhibition of leukotriene release by soman in human basophils

    SciTech Connect

    Meier, H.L.; Warner, J.; MacGlashan, D.W.

    1995-12-31

    Previous studies noted that the serine esterase inhibitor, soman, could induce histamine release from human basophils. To investigate the mechanisms by which soman causes histamine release (a preformed mediator), we also examined its ability to induce leukotriene release (a newly synthesized mediator) from basophils. We found that no leukotriene release followed activation with soman, while histamine release was usually greater than 70%. In addition, soman and diisopropyl-fluorophosphate were found actively to suppress low level spontaneous leukotriene release as well as ongoing leukotriene release induced by anti-IgE antibody. Soman (0.3 mM) was able to stop leukotriene release as rapidly as the calcium chelator, EDTA. In a series of control experiments, it was noted that soman did not influence the metabolism of LTC4 to LTD4 or LTE4 (for which little metabolism occurred), eliminating the possibility that reduced LTC4 release could have resulted from its enhanced metabolism. Therefore, using one compound (soman), basophils could be simultaneously activated to degranulate while having the pathway leading to leukotriene release actively suppressed. These results provide further evidence that histamine and leukotriene release are independent pathways resulting from the activation of basophils.

  15. Cinnamaldehyde derivatives inhibit degranulation and inflammatory mediator production in rat basophilic leukemia cells.

    PubMed

    Ahn, Sejin; Kim, Eunhee; Lee, Kooyeon; Lee, Deug-Chan

    2016-09-01

    Mast cells play a critical role in allergic diseases. Therefore, development of new therapeutic agents that suppresses the activation of mast cells may help prevent or treat allergic diseases. Here, we investigated the anti-allergic effects of 4-chloro-cinnamaldehyde and 4-trifluoro-cinnamaldehyde in RBL-2H3 cells. β-Hexosaminidase assays revealed that degranulation of RBL-2H3 cells was decreased following treatment with 60μM 4-chloro-cinnamaldehyde or 4-trifluoro-cinnamaldehyde. Moreover, quantitative real-time reverse transcription polymerase chain reaction showed that the relative expression levels of tumor necrosis factor-α, interleukin-4, and cyclooxygenase-2 mRNAs were decreased in RBL-2H3 cells treated with 4-chloro-cinnamaldehyde and 4-trifluoro-cinnamaldehyde in a concentration-dependent manner. Additionally, 4-chloro-cinnamaldehyde blocked the phosphorylation of MKKs and MAPKs. These data clearly suggested that 4-chloro-cinnamaldehyde and 4-trifluoro-cinnamaldehyde had inhibitory effects on the inflammatory responses of mast cells and may have potential as novel therapeutic agents for the prevention or treatment of allergic diseases.

  16. Mitochondrial calcium uniporter inhibition attenuates mouse bone marrow-derived mast cell degranulation induced by beta-1,3-glucan

    PubMed Central

    Cuong, Dang Van; Kim, Hyoung Kyu; Marquez, Jubert; Kim, Nari; Ko, Kyung Soo; Rhee, Byoung Doo

    2016-01-01

    Mast cells are primary mediators of allergic inflammation. Beta-1,3-glucan (BG) protects against infection and shock by activating immune cells. Activation of the BG receptor induces an increase in intracellular Ca2+, which may induce exocytosis. However, little is known about the precise mechanisms underlying BG activation of immune cells and the possible role of mitochondria in this process. The present study examined whether BG induced mast cell degranulation, and evaluated the role of calcium transients during mast cell activation. Our investigation focused on the role of the mitochondrial calcium uniporter (MCU) in BG-induced degranulation. Black mouse (C57) bone marrow-derived mast cells were stimulated with 0.5 µg/ml BG, 100 µg/ml peptidoglycan (PGN), or 10 µM A23187 (calcium ionophore), and dynamic changes in cytosolic and mitochondrial calcium and membrane potential were monitored. BG-induced mast cell degranulation occurred in a time-dependent manner, and was significantly reduced under calcium-free conditions. Ruthenium red, a mitochondrial Ca2+ uniporter blocker, significantly reduced mast cell degranulation induced by BG, PGN, and A23187. These results suggest that the mitochondrial Ca2+ uniporter has an important regulatory role in BG-induced mast cell degranulation. PMID:26937218

  17. [Modified tests basophil degranulation and leukocyte migration inhibition factor in drug allergy. Study 2009-2014].

    PubMed

    Irigoyen-Coria, María Lourdes; Rojo-Gutiérrez, María Isabel; Meyer-Gómez, Rubén Humberto; Leyva-Carmona, Isabel; Zendejas-Buitrón, Víctor Manuel; García-Ruiz, Angélica Dinorah; Mellado-Ábrego, Jaime; García-Ortega, Ilayalid; Castillo-Narváez, Gloria

    2016-01-01

    Antecedentes: Existe incremento de reacciones adversas a medicamentos y pocos estudios para el diagnóstico. Objetivo: Determinar la utilidad de pruebas modificadas de degranulación de basófilos (DB) y del factor inhibidor de la migración de leucocitos (LIF, leukocyte migration inhibition factor) para comprobar la hipersensibilidad a medicamentos. Métodos: Se estudiaron 177 pacientes, de uno y otro sexo, con diagnóstico de hipersensibilidad a medicamentos, en quienes se determinó pruebas modificadas de DB, LIF, o ambas entre 2009 y 2014. Se parearon con controles positivos, negativos y población no alérgica. Las solicitudes se emitieron de acuerdo con el tipo de hipersensibilidad, considerando tipo I a DB y tipo IV a LIF Resultados: 170 pacientes (96.04%) fueron positivos al menos a un medicamento (RR, 4.71). Se realizaron 561 pruebas modificadas de DB (73.62%) y 201 de LIF (26.37%). El sexo femenino fue más frecuente (64.41%); la edad promedio fue de 38.5 años. La prueba modificada de DB resultó positiva en 70.23% y la de LIF en 67.16%. La sensibilidad de las pruebas se incrementó en forma complementaria y a dos diluciones. La correlación de las pruebas fue altamente significativa. Conclusiones: Las mujeres presentan más reacciones a fármacos. La prueba modificada de DB es útil en cualquier edad. Como los medicamentos pueden activar uno u otro mecanismo de hipersensibilidad es importante solicitar las pruebas simultáneamente.

  18. Cardiovascular stress of photochemotherapy (PUVA)

    SciTech Connect

    Ciafone, R.A.; Rhodes, A.R.; Audley, M.; Freedberg, I.M.; Abelmann, W.H.

    1980-11-01

    The recently devised therapy for psoriasis and related skin diseases, consisting of long-wave ultraviolet light and oral 8-methoxypsoralen (PUVA), was investigated for its cardiovascular effects. In seventeen patients, long-wave ultraviolet light therapy in a treatment enclosure (mean duration, 19.3 minutes) resulted in ambient temperatures of 39.2 degrees C +/- 2.1 degrees C (SD) and skin temperatures of 38.2 degrees C +/- 1.4 degrees C. In upright subjects, heart rate rose 30.8% to 114.4 +/- 25.2 beats per minute (bpm). Intensive room air conditioning, outside of the treatment enclosure, although significantly lowering skin and ambient temperatures, did not affect the heart rates significantly. PUVA therapy is associated with a definite cardiovascular stress when the box type of therapeutic unit is used. Possible modifications are discussed.

  19. Suppression of phospholipase Cγ1 phosphorylation by cinnamaldehyde inhibits antigen-induced extracellular calcium influx and degranulation in mucosal mast cells.

    PubMed

    Kageyama-Yahara, Natsuko; Wang, Xiaoyu; Katagiri, Tatsuo; Wang, Ping; Yamamoto, Takeshi; Tominaga, Makoto; Kadowaki, Makoto

    2011-12-16

    Antigen-IgE-mediated mucosal mast-cell activation is critical in the development of food allergies. Cinnamaldehyde, a major constituent of Cinnamomi cortex, dose-dependently inhibited the antigen-IgE-induced degranulation of mucosal-type bone-marrow derived mast cells (mBMMCs) and RBL-2H3 cells. Cinnamaldehyde also suppressed the elevation of the intracellular Ca(2+) level that is induced by the extracellular Ca(2+) influx in antigen-IgE-stimulated mBMMCs. Furthermore, tyrosine phosphorylation of phospholipase C (PLC) γ1, which is a crucial activation switch for the intracellular Ca(2+) mobilization in mast cells, was attenuated by cinnamaldehyde. Together, our results demonstrated that cinnamaldehyde suppressed the intracellular Ca(2+) mobilization and the degranulation of mucosal mast cells by inhibiting the activity of the IgE receptor-PLCγ-Ca(2+) influx pathway. These findings suggest that cinnamaldehyde may have therapeutic potential in mucosal mast cell-related allergic diseases, such as food allergies.

  20. Nicotine inhibits Fc epsilon RI-induced cysteinyl leukotrienes and cytokine production without affecting mast cell degranulation through alpha 7/alpha 9/alpha 10-nicotinic receptors.

    PubMed

    Mishra, Neerad C; Rir-sima-ah, Jules; Boyd, R Thomas; Singh, Shashi P; Gundavarapu, Sravanthi; Langley, Raymond J; Razani-Boroujerdi, Seddigheh; Sopori, Mohan L

    2010-07-01

    Smokers are less likely to develop some inflammatory and allergic diseases. In Brown-Norway rats, nicotine inhibits several parameters of allergic asthma, including the production of Th2 cytokines and the cysteinyl leukotriene LTC(4). Cysteinyl leukotrienes are primarily produced by mast cells, and these cells play a central role in allergic asthma. Mast cells express a high-affinity receptor for IgE (FcepsilonRI). Following its cross-linking, cells degranulate and release preformed inflammatory mediators (early phase) and synthesize and secrete cytokines/chemokines and leukotrienes (late phase). The mechanism by which nicotine modulates mast cell activation is unclear. Using alpha-bungarotoxin binding and quantitative PCR and PCR product sequencing, we showed that the rat mast/basophil cell line RBL-2H3 expresses nicotinic acetylcholine receptors (nAChRs) alpha7, alpha9, and alpha10; exposure to exceedingly low concentrations of nicotine (nanomolar), but not the biologically inactive metabolite cotinine, for > or = 8 h suppressed the late phase (leukotriene/cytokine production) but not degranulation (histamine and hexosaminidase release). These effects were unrelated to those of nicotine on intracellular free calcium concentration but were causally associated with the inhibition of cytosolic phospholipase A(2) activity and the PI3K/ERK/NF-kappaB pathway, including phosphorylation of Akt and ERK and nuclear translocation of NF-kappaB. The suppressive effect of nicotine on the late-phase response was blocked by the alpha7/alpha9-nAChR antagonists methyllycaconitine and alpha-bungarotoxin, as well as by small interfering RNA knockdown of alpha7-, alpha9-, or alpha10-nAChRs, suggesting a functional interaction between alpha7-, alpha9-, and alpha10-nAChRs that might explain the response of RBL cells to nanomolar concentrations of nicotine. This "hybrid" receptor might serve as a target for novel antiallergic/antiasthmatic therapies.

  1. Pretreatment with Evans blue, a stimulator of BK(Ca) channels, inhibits compound 48/80-induced shock, systemic inflammation, and mast cell degranulation in the rat.

    PubMed

    Fu, Yaw-Syan; Kuo, Su-Yu; Lin, Hsuan-Yea; Chen, Chun-Lin; Huang, Shi-Ying; Wen, Zhi-Hong; Lee, Kun-Zer; Huang, Hung-Tu

    2015-09-01

    The present study demonstrated that intravenous injection of a high dose of compound 48/80 to the rat induced 50% drop, within a few min, in the mean arterial pressure and pulse pressure as well as systemic inflammatory plasma leakage that might lead to circulatory and respiratory failure. We also investigated whether pretreatment with Evans blue, a stimulator of BK(Ca) channels, could exert inhibitory effect against compound C48/80-induced allergic circulatory shock and systemic inflammation. Different groups of Sprague-Dawley rats received an intravenous injection of a dose of Evans blue (0, 5, 10, or 50 mg/kg) just 20 s prior to injection of compound 48/80 (200 μg/kg, over 2 min). The present study found that pretreatment with Evans blue in a dose of 10 or 50 mg/kg exerted acute inhibitory effect on compound 48/80-induced sudden drop in mean arterial and pulse pressures. We also showed that pretreatment with Evans blue in a dose of 5, 10, or 50 mg/kg significantly inhibited compound 48/80-induced extensive plasma extravasation, mast cell degranulation, and edema formation in various organs including the airways, esophagus, and skin. Pretreatment with Evans blue 50 mg/kg 1 h earlier exhibited longer-term inhibitory effect on compound 48/80-induced arterial hypotension and systemic inflammation. We concluded that Evans blue pretreatment prevented rats from compound 48/80-triggered allergic shock and systemic inflammation, possibly mainly through inhibition of mast cell degranulation. Evans blue might be potentially useful in elucidating the mechanism and acting as a therapeutic agent of allergic shock and systemic inflammation.

  2. Melanin granula distribution and phagocytosis in psoriasis vulgaris after PUVA therapy.

    PubMed

    Stüttgen, G; Brinkmann-Raestrupp, I; Haller, L; Kentsch, V; Schalla, W

    1979-02-23

    Melanin-containing basal cells of the epidermis, melanin-containing macrophages, mast cells, eosinophilic granulocytes and plasma cells were quantitatively investigated with the purpose of gaining an understanding of the quantitative changes in these cell systems under PUVA therapy. This patients have been exposed to solar radiation some weeks or months before the begin of the PUVA-treatment. Different dying-processes were used to investigate biopsy samples of psoriatically healthy and psoriatically affected skin, from 28 patients before, and 39 patients after PUVA therapy, using a 2 d micrometer with a field of view of 0.1 mm2. Altogether more than 9,000 fields of view have been analysed. The average radiation amount was 12 irradiations with an average total energy of 21.5 J/cm2. It was found that the count of granula-containing basal layer cells decreases in the psoriatic "healthy" region due to pigment incontinence and increase in the psoriatically affected region. The subepidermal melanin-containing phagocytes increase in both regions to a similar extent. In the case of the mast cells there was no trend to degranulation. The count of eosinophilic granulocytes and plasma cells was unchanged.

  3. Effects of PUVA on the eye

    SciTech Connect

    Backman, H.A.

    1982-01-01

    Psoriasis is a common skin disease which may be treated with 8-methoxy psoralen and long-wave ultraviolet light (PUVA). Eye protection is provided during and after treatment to prevent the development of photokeratitis and cataracts. Fifteen patients, treated with medication and ultraviolet A (UVA) had an initial complete eye examination and a repeat examination after each treatment. No patients developed cataracts but almost one-half of the patients had a mild form of photokeratoconjunctivitis. The ocular manifestations included photophobia, conjunctivitis, keratitis, and dry eyes. Tear break-up time was reduced significantly immediately after treatment for two patients but returned to normal 8 hr later. Dermatologists who employ PUVA treatments should be concerned about photokeratoconjunctivitis and the dry-eye ocular manifestations included photophobia, conjunctivitis, keratitis, and dry eyes. Tear break-up time was reduced significantly immediately after treatment for two patients but returned to normal 8 hr later. Dermatologists who employ PUVA treatments should be concerned about photokeratoconjunctivitis and the dry-eye ocular manifestations included photophobia, conjunctivitis, keratitis, and dry eyes. Tear break-up time was reduced significantly immediately after treatment for two patients but returned to normal 8 hr later. Dermatologists who employ PUVA treatments should be concerned about photokeratoconjunctivitis and the dry-eye syndrome.

  4. Mathematical model of laser PUVA psoriasis treatment

    NASA Astrophysics Data System (ADS)

    Medvedev, Boris A.; Tuchin, Valery V.; Yaroslavsky, Ilya V.

    1991-05-01

    In order to optimize laser PUVA psoriasis treatment we develop the mathematical model of the dynamics of cell processes within epidermis. We consider epidermis as a structure consisting of N cell monolayers. There are four kinds of cells that correspond to four epidermal strata. The different kinds of cells can exist within a given monolayer. We assume that the following cell processes take place: division, death and transition from one stratum to the following. Discrete transition of cells from stratum j to j + 1 approximates to real differentiation.

  5. Microvascular leakage of plasma proteins after PUVA and UVA

    SciTech Connect

    Staberg, B.; Worm, A.M.; Rossing, N.; Brodthagen, H.

    1982-04-01

    The transcapillary escape rate of albumin (TERalb), is a parameter of the leakage of macromolecules from the total microvasculature. In patients with psoriasis short-term PUVA treatment induces an increase in TERalb. In this study TERalb was measured in 3 groups of normal humans treated with PUVA, UVA and 8-methoxypsoralen. Treatment with PUVA and UVA caused a statistically significant increase in TERalb, whereas treatment with 8-methoxypsoralen did not induce any measurable changes. It is concluded that the UVA irradiation causes the abnormal leakage of macromolecules, whereas psoralen is not the responsible component. Furthermore the phenomenon can be elicited in normals and is not based on a preexisting psoriasis.

  6. Influence of PUVA and UVB radiation on delayed hypersensitivity in the guinea pig

    SciTech Connect

    Morison, W.L.; Parrish, J.A.; Woehler, M.E.; Krugler, J.I.; Bloch, K.J.

    1981-06-01

    Exposure of guinea pigs to UVA (320--400 nm) radiation following administration of 8-methoxypsoralen by gavage (referred to by the acronym, PUVA) or exposure to UVB (290--320 nm) radiation, produced suppression of the cutaneous delayed hypersensitivity reaction at the site of exposure to radiation and at distant nonexposed sites. In these experiments, the animals were immunized by injection of dinitrophenyl-bovine gamma-globulin (DNP-BGG) in complete Freund's adjuvant and delayed hypersensitivity responses were provoked by intradermal injections of DNP-BGG, DNP and BGG on the flanks. Exposure to erythemogenic doses of either PUVA or UVB radiation for 7 days prior to immunization and for the 7 days between immunization and challenge (total period of radiation: 14 days) produced inhibiton of responses to each of the test substances. In addition, treatment with erythemogenic doses of PUVA either for 7 days prior to immunization or during the interval between immunization and challenge with DNP-BGG, inhibited the delayed hypersensitivity responses at the site of irradiation and at a nonexposed site. These findings suggest that in vivo exposure to nonionizing radiation leads to both local and systemic alteration of certain immune responses.

  7. Inhibition of. beta. -bungarotoxin binding to brain membranes by mast cell degranulating peptide, toxin I, and ethylene glycol bis(. beta. -aminoethyl ether)-N,N,N',N'-tetraacetic acid

    SciTech Connect

    Schmidt, R.R.; Betz, H.; Rehm, H.

    1988-02-09

    The presynaptically active snake venom neurotoxin ..beta..-bungarotoxin (..beta..-Butx) is known to affect neurotransmitter release by binding to a subtype of voltage-activated K/sup +/ channels. Here the authors show that mast cell degranulating (MCD) peptide from bee venom inhibits the binding of /sup 125/I-labeled ..beta..-Butx to chick and rat brain membranes with apparent K/sub i/ values of 180 nM and 1100 nM, respectively. The mechanisms of inhibition of MCD peptide is noncompetitive, as is inhibition of /sup 125/I-..beta..-Butx binding by the protease inhibitor homologue from mamba venom, toxin I. ..beta..-Butx and its binding antagonists thus bind to different sites of the same membrane protein. Removal of Ca/sup 2 +/ by ethylene glycol bis(..beta..-aminoethyl ether)-N,N,N',N'-tetraacetic acid inhibits the binding of /sup 125/I-..beta..-Butx by lowering its affinity to brain membranes.

  8. Long-term stability of 8-methoxypsoralen in ointments for topical PUVA therapy ('Cream-PUVA').

    PubMed

    Martens-Lobenhoffer, J; Rinke, M; Lösche, D; Gollnick, H

    1999-01-01

    8-Methoxypsoralen (8-MOP) is an established photochemotherapeutic agent for PUVA therapy. Recently, a so-called 'cream-PUVA' modality was introduced into therapy of psoriasis and other dermatoses. Little is known, however, about the stability of 8-MOP in ointments used for the topical application of this compound. Therefore, we investigated the long-term stability of 8-MOP in three different ointments, Unguentum Cordes(TM), Cold Cream Naturel(TM) and a water-containing gel on the basis of Carbopol 940. All three ointments were prepared with 8-MOP concentrations of 0.05 and 0.005%, and stored over 12 weeks at room temperature (19-20 degrees C) and at 5 degrees C. 8-MOP concentrations were measured at days 1, 8, 15, 29, 57 and 88 after preparation by thin-layer chromatography (TLC). The ointments were dissolved in an organic solvent, 10 microl were transferred onto the TLC plate and the chromatograms were developed first in toluene and then in toluene/ethyl acetate 2:1 v/v to resolve 8-MOP from the ointment constituents. The peak heights of 8-MOP were used for quantitation. The intraday variabilities are <3% for Unguentum Cordes and Cold Cream Naturel and <6% for the Carbopol 940 gel. The interday variabilities were <6.3% in all cases. In Unguentum Cordes and Cold Cream Naturel the concentrations of 8-MOP remain stable, but in Unguentum Cordes the emulsion began to break up after 8 weeks. In the Carbopol gel, only about 40% of the nominal concentrations of 8-MOP were found and they decrease significantly at storage at 5 degrees C. We conclude that the Carbopol gel seems to be unsuitable for PUVA therapy, whereas Cold Cream Naturel shows the best results.

  9. PUVA: A Monte Carlo code for intra-articular PUVA treatment of arthritis

    SciTech Connect

    Descalle, M.A.; Laing, T.J.; Martin, W.R.

    1996-12-31

    Current rheumatoid arthritis treatments are only partially successful. Intra-articular psoralen-ultraviolet light (PUVA) phototherapy appears to be a new and valid alternative. Ultraviolet laser light (UVA) delivered in the knee joint through a fiber optic is used in combination with 8-methoxypsoralen (8-MOP), a light-sensitive chemical administered orally. A few hours after ingestion, the psoralen has diffused in all body cells. Once activated by UVA light, it binds to biological molecules, inhabiting cell division and ultimately causing local control of the arthritis. The magnitude of the response is proportional to the number of photoproducts delivered to tissues (i.e., the number of absorbed photons): the PUVA treatment will only be effective if a sufficient and relatively uniform dose is delivered to the diseased synovial tissues, while sparing other tissues such as cartilage. An application is being developed, based on analog Monte Carlo methods, to predict photon densities in tissues and the minimum number of intra-articular catheter positions necessary to ensure proper treatment of the diseased zone. Other interesting aspects of the problem deal with the compexity of the joint geometry, the physics of light scattering in tissues (a relatively new field of research that is not fully understood because of the variety of tissues and tissue components), and, finally, the need to include optic laws (reflection and refraction) at interfaces.

  10. Cytochrome P450 CYP1B1 Interacts with 8-Methoxypsoralen (8-MOP) and Influences Psoralen-Ultraviolet A (PUVA) Sensitivity

    PubMed Central

    Deeni, Yusuf Y.; Ibbotson, Sally H.; Woods, Julie A.; Wolf, C. Roland; Smith, Gillian

    2013-01-01

    Background There are unpredictable inter-individual differences in sensitivity to psoralen-UVA (PUVA) photochemotherapy, used to treat skin diseases including psoriasis. Psoralens are metabolised by cytochrome P450 enzymes (P450), and we hypothesised that variability in cutaneous P450 expression may influence PUVA sensitivity. We previously showed that P450 CYP1B1 was abundantly expressed in human skin and regulated by PUVA, and described marked inter-individual differences in cutaneous CYP1B1 expression. Objectives We investigated whether CYP1B1 made a significant contribution to 8-methoxypsoralen (8-MOP) metabolism, and whether individuality in CYP1B1 activity influenced PUVA sensitivity. Methods We used E. coli membranes co-expressing various P450s and cytochrome P450 reductase (CPR) to study 8-MOP metabolism and cytotoxicity assays in CYP1B1-expressing mammalian cells to assess PUVA sensitivity. Results We showed that P450s CYP1A1, CYP1A2, CYP1B1, CYP2A6 and CYP2E1 influence 8-MOP metabolism. As CYP1B1 is the most abundant P450 in human skin, we further demonstrated that: (i) CYP1B1 interacts with 8-MOP (ii) metabolism of the CYP1B1 substrates 7-ethoxyresorufin and 17-β-estradiol showed concentration-dependent inhibition by 8-MOP and (iii) inhibition of 7-ethoxyresorufin metabolism by 8-MOP was influenced by CYP1B1 genotype. The influence of CYP1B1 on PUVA cytotoxicity was further investigated in a Chinese hamster ovary cell line, stably expressing CYP1B1 and CPR, which was more sensitive to PUVA than control cells, suggesting that CYP1B1 metabolises 8-MOP to a more phototoxic metabolite(s). Conclusion Our data therefore suggest that CYP1B1 significantly contributes to cutaneous 8-MOP metabolism, and that individuality in CYP1B1 expression may influence PUVA sensitivity. PMID:24086543

  11. Mathematical modeling for laser PUVA treatment of psoriasis

    NASA Astrophysics Data System (ADS)

    Medvedev, Boris A.; Tuchin, Valery V.; Yaroslavsky, Ilya V.

    1991-06-01

    The justifaction of method of the laser PUVA (LPUVA) therapy, the description of an UVA therapeutic system, the preliminary results of using the nitrogen gas laser as an UVA source for LPUVA chamber and in some other fields of application in dermatology are given.

  12. Different activation signals induce distinct mast cell degranulation strategies

    PubMed Central

    Sibilano, Riccardo; Marichal, Thomas; Reber, Laurent L.; Cenac, Nicolas; McNeil, Benjamin D.; Dong, Xinzhong; Hernandez, Joseph D.; Sagi-Eisenberg, Ronit; Hammel, Ilan; Roers, Axel; Valitutti, Salvatore; Tsai, Mindy

    2016-01-01

    Mast cells (MCs) influence intercellular communication during inflammation by secreting cytoplasmic granules that contain diverse mediators. Here, we have demonstrated that MCs decode different activation stimuli into spatially and temporally distinct patterns of granule secretion. Certain signals, including substance P, the complement anaphylatoxins C3a and C5a, and endothelin 1, induced human MCs rapidly to secrete small and relatively spherical granule structures, a pattern consistent with the secretion of individual granules. Conversely, activating MCs with anti-IgE increased the time partition between signaling and secretion, which was associated with a period of sustained elevation of intracellular calcium and formation of larger and more heterogeneously shaped granule structures that underwent prolonged exteriorization. Pharmacological inhibition of IKK-β during IgE-dependent stimulation strongly reduced the time partition between signaling and secretion, inhibited SNAP23/STX4 complex formation, and switched the degranulation pattern into one that resembled degranulation induced by substance P. IgE-dependent and substance P–dependent activation in vivo also induced different patterns of mouse MC degranulation that were associated with distinct local and systemic pathophysiological responses. These findings show that cytoplasmic granule secretion from MCs that occurs in response to different activating stimuli can exhibit distinct dynamics and features that are associated with distinct patterns of MC-dependent inflammation. PMID:27643442

  13. PUVA therapy damages psoriatic and normal lymphoid cells within milliseconds.

    PubMed

    Böhm, F; Meffert, H; Bauer, E

    1986-01-01

    Results of previous investigations have indicated that photochemotherapy (PUVA) attacks membranes of target cells. Using the combination of a stopped-flow technique and laser irradiation we were able to prove that the fast PUVA effect is explainable solely by the membrane damage. Lymphoid cells of healthy persons or psoriatics were taken, within 1 ms mixed with 8-methoxy-psoralen (8-MOP) at concentrations of 1.0, 0.1, and 0.5 microgram/ml, and then irradiated by a 337-nm laser pulse (0.5 mJ/cm2) lasting some picoseconds. Approximately 1 ms after administration of 8-MOP to the cell surface at least 10% of the cells were damaged, as could be judged using the standard trypan blue exclusion test. This happened at 8-MOP concentrations of 1.0 or 0.1 microgram/ml plus laser irradiation, but a concentration of 0.05 microgram/ml 8-MOP plus laser exposure did not cause any effect within 8 ms after mixing. There was no difference between using lymphoid cells from healthy persons or from psoriatics. The fact that only a very short time is necessary before cell damage occurs means that, as far as the fast PUVA effect is concerned, a photochemical reaction involving nuclear DNA can be discounted.

  14. Cyclin-dependent kinase 5 regulates degranulation in human eosinophils.

    PubMed

    Odemuyiwa, Solomon O; Ilarraza, Ramses; Davoine, Francis; Logan, Michael R; Shayeganpour, Anooshirvan; Wu, Yingqi; Majaesic, Carina; Adamko, Darryl J; Moqbel, Redwan; Lacy, Paige

    2015-04-01

    Degranulation from eosinophils in response to secretagogue stimulation is a regulated process that involves exocytosis of granule proteins through specific signalling pathways. One potential pathway is dependent on cyclin-dependent kinase 5 (Cdk5) and its effector molecules, p35 and p39, which play a central role in neuronal cell exocytosis by phosphorylating Munc18, a regulator of SNARE binding. Emerging evidence suggests a role for Cdk5 in exocytosis in immune cells, although its role in eosinophils is not known. We sought to examine the expression of Cdk5 and its activators in human eosinophils, and to assess the role of Cdk5 in eosinophil degranulation. We used freshly isolated human eosinophils and analysed the expression of Cdk5, p35, p39 and Munc18c by Western blot, RT-PCR, flow cytometry and immunoprecipitation. Cdk5 kinase activity was determined following eosinophil activation. Cdk5 inhibitors were used (roscovitine, AT7519 and small interfering RNA) to determine its role in eosinophil peroxidase (EPX) secretion. Cdk5 was expressed in association with Munc18c, p35 and p39, and phosphorylated following human eosinophil activation with eotaxin/CCL11, platelet-activating factor, and secretory IgA-Sepharose. Cdk5 inhibitors (roscovitine, AT7519) reduced EPX release when cells were stimulated by PMA or secretory IgA. In assays using small interfering RNA knock-down of Cdk5 expression in human eosinophils, we observed inhibition of EPX release. Our findings suggest that in activated eosinophils, Cdk5 is phosphorylated and binds to Munc18c, resulting in Munc18c release from syntaxin-4, allowing SNARE binding and vesicle fusion, with subsequent eosinophil degranulation. Our work identifies a novel role for Cdk5 in eosinophil mediator release by agonist-induced degranulation.

  15. Involvement of BLT1 endocytosis and Yes kinase activation in leukotriene B4-induced neutrophil degranulation.

    PubMed

    Gaudreault, Eric; Thompson, Charles; Stankova, Jana; Rola-Pleszczynski, Marek

    2005-03-15

    One of the important biological activities of human neutrophils is degranulation, which can be induced by leukotriene B4 (LTB4). Here we investigated the intracellular signaling events involved in neutrophil degranulation mediated by the high affinity LTB4 receptor, BLT1. Peripheral blood neutrophils as well as the promyeloid PLB-985 cell line, stably transfected with BLT1 cDNA and differentiated into a neutrophil-like cell phenotype, were used throughout this study. LTB4-induced enzyme release was inhibited by 50-80% when cells were pretreated with the pharmacological inhibitors of endocytosis sucrose, Con A and NH4Cl. In addition, transient transfection with a dominant negative form of dynamin (K44A) resulted in approximately 70% inhibition of ligand-induced degranulation. Pretreating neutrophils or BLT1-expressing PLB-985 cells with the Src family kinase inhibitor PP1 resulted in a 30-60% inhibition in BLT1-mediated degranulation. Yes kinase, but not c-Src, Fgr, Hck, or Lyn, was found to exhibit up-regulated kinase activity after LTB4 stimulation. Moreover, BLT1 endocytosis was found to be necessary for Yes kinase activation in neutrophils. LTB4-induced degranulation was also sensitive to inhibition of PI3K. In contrast, it was not affected by inhibition of the mitogen-activated protein kinase MEK kinase, the Janus kinases, or the receptor tyrosine kinase epidermal growth factor receptor or platelet-derived growth factor receptor. Taken together, our results suggest an essential role for BLT1 endocytosis and Yes kinase activation in LTB4-mediated degranulation of human neutrophils.

  16. Effect of methylmercury on the rat mast cell degranulation

    NASA Astrophysics Data System (ADS)

    Graevskaya, E. E.; Yasutake, A.; Aramai, R.; Rubin, A. B.

    2003-05-01

    Methylmercury is the well-known neurotoxicant as weil as a modulator of the immune system. We investigated the effects of MeHg on the rat mast cell degranulation induced by nonimmunological stimuli (the selective liberator of histamine, compound 48/80, and calcium ionophore A23187) both in vivo and in vitro. In 8, 12 and 15 days afterthe final administration of MeHg we observed the suppression of calcium ionophore A23187-and 48/80-induced histamine release, which enhanced with time. In experiments in vitro incubation of peritoneal mast cells with MeHg alone in the dose range 10^{-8} to 10^{-6} did not induce mast cell degranulation, however modified the activation of mast cells by compound 48/80, and calcium ionophore A23187. We observed activation of stimulated secretion by preliminary incubation with low dose of MeHg 10^{-8} M and inhibition by dose of MeHg 10^{-6} M. These results show that MeHg treatment can modify mast cell function in vivo and in vitro and provide insight into the understanding what role this cell has in the pathogenesis of Minamata disease-comlected disorders.

  17. Inhibitory effects of guarana seed extract on passive cutaneous anaphylaxis and mast cell degranulation.

    PubMed

    Jippo, Tomoko; Kobayashi, Yuko; Sato, Harumi; Hattori, Atsushi; Takeuchi, Hiroaki; Sugimoto, Keiichiro; Shigekawa, Munekazu

    2009-09-01

    This study investigated the effects of guarana seed extract (GSE) on an anti-allergic mechanism. GSE orally administered inhibited the anti-dinitrophenol IgE-induced passive cutaneous anaphylaxis reaction in mice. Furthermore, it inhibited the degranulation of rat basophilic leukemia RBL-2H3 cells. It had no cytotoxicity on RBL-2H3 cells. These results show that GSE is a candidate for effective therapeutic material for allergic diseases.

  18. Evaluation of PUVA, topical corticosteroids and the combination of both in the treatment of psoriasis.

    PubMed

    Schmoll, M; Henseler, T; Christophers, E

    1978-12-01

    A total of 90 patients with psoriasis were treated either by photochemotherapy (PUVA) or by topical steroids under occlusion (TOC). In a third group of patients a combination of both regimens was applied. All patients received approximately 15 treatments of either type. During therapy, biopsies were taken in all treatment groups and the epidermal thickness was monitored planimetrically. After clearing of the skin the patients were left without treatment and the time of onset of new lesions was recorded. While TOC produced rapid clearing of the skin this was followed by early relapses (in 50% of the patients after 3 weeks). PUVA reduced psoriatic hyperplasia more slowly; however, 50% of the patients remained free of psoriasis for approximately 10 weeks after clearance. Psoriasis treated with steroids under occlusion together with PUVA showed a significantly faster return of the skin to normal as compared to PUVA. As in PUVA-treated patients relapses occurred after approximately 12 weeks is this group. Therefore the combination of both treatments appears to be advantageous for rapid skin clearance and comparatively long remissions.

  19. Effect of Pakistani medicinal plants on IgE/antigen- and ionophore-induced mucosal mast cells degranulation.

    PubMed

    Zaidi, Syed Faisal; Kim, Ji-Hyun; Tomoe, Yashiro; Usmanghani, Khan; Kadowaki, Makoto

    2014-07-01

    Cumulative evidence has now demonstrated the stimulation of mucosal mast cells by both allergic and non-allergic triggers and their inhibition as a potential therapeutic target in many diseases like food allergy and ulcerative colitis. Hence, we screened medicinal plants from Pakistan against antigen- and ionophore-induced degranulation of mucosal mast cells. Aqueous ethanol extracts were screened. IgE/antigen- and A23187-induced degranulation of mucosal-type murine bone marrow derived mast cells (mBMMCs) were screening assays and β-hexosaminidase released from degranulated mBMMCs was measured. Real time-polymerase chain reaction was employed to examine the expression of TNF-α and IL-4 mRNA. Acetoxychavicol acetate, was examined by degranulation assays and real time-PCR. Among the ten plants screened against IgE/antigen stimulated degranulation, five plants; Alpinia galangal, Mentha arvensis, Myrtus communis, Polygonum bistorta and Syzygium aromaticum demonstrated significant (p<0.01) suppression of the degranulation at 100 μg/ml. Of them, Alpinia galangal showed significant (p<0.01) inhibition at 32 mg/ml. In A23187-induced degranulation, all plants showed significant (p<0.01) inhibition at 100 μg/ml except Tamarix dioica. Again Alpinia galangal exhibited significant (p<0.01) suppression at 32 μg/ml. In a concentration dependent assay, Alpinia galangal revealed significant suppression at 10 μg/ml against A23187-stimulated degranulation. Acetoxychavicol acetate demonstrated significant (p<0.01) inhibition at 3.2 μM in IgE/antigen-treated cells and at 10 μM in A23187-treated cells. Furthermore, both Alpinia galangal and acetoxychavicol acetate suppressed the IgE/antigen- and A23187-enhanced mRNA expression of inflammatory cytokines, TNF-a and IL-4, in mBMMCs. Our findings revealed the suppressive effect of Alpinia galangal and acetoxychavicol acetate on degranulation of mBMMCs by allergic and non-allergic stimuli, which can be utilized for future drug

  20. Effect of fruits of Opuntia elatior Mill on mast cell degranulation

    PubMed Central

    Chauhan, Sanjay P.; Sheth, N. R.; Suhagia, B. N.

    2015-01-01

    Background: The presence of potentially active nutrients and their multifunctional properties make prickly pear a perfect candidate for the production of phytopharmaceutical products. Among the numerous Opuntia species, bioactive compounds have been isolated and characterized primarily from Opuntia ficus-indica, Opuntia polycantha, Opuntia stricta, Opuntia dilleni for various medicinal properties. Objective: Based on the traditional use of prickly pear for enhancement of immune function, the objective of the present study to evaluate the effect of prickly pear on mast cell degranulation function. Materials and Methods: The Opuntia fruit juice (OFJ) (10-200 μl/ml) were studied for the effect on sensitized rat peritoneal mast cell degranulation induced by immunological (egg albumin), and nonimmunological (compound 48/80) stimuli and compared with that of the reference standard, sodium cromoglycate and ketotifen (10 μg/ml). Results and Conclusion: The OFJ exhibited significantly (P < 0.001) concentration dependent inhibition of mast cell degranulation. The IC50 value of OFJ was found 12.24 and 18 μl/ml for immunological and nonimmunological induced mast cell degranulation, respectively. The betacyanin is an active principle compound in prickly pear that may responsible for mast cell stabilizing action. PMID:25883521

  1. Modulation of Basophils' Degranulation and Allergy-Related Enzymes by Monomeric and Dimeric Naphthoquinones

    PubMed Central

    Pinho, Brígida R.; Sousa, Carla; Valentão, Patrícia; Oliveira, Jorge M. A.; Andrade, Paula B.

    2014-01-01

    Allergic disorders are characterized by an abnormal immune response towards non-infectious substances, being associated with life quality reduction and potential life-threatening reactions. The increasing prevalence of allergic disorders demands for new and effective anti-allergic treatments. Here we test the anti-allergic potential of monomeric (juglone, menadione, naphthazarin, plumbagin) and dimeric (diospyrin and diosquinone) naphthoquinones. Inhibition of RBL-2H3 rat basophils' degranulation by naphthoquinones was assessed using two complementary stimuli: IgE/antigen and calcium ionophore A23187. Additionally, we tested for the inhibition of leukotrienes production in IgE/antigen-stimulated cells, and studied hyaluronidase and lipoxidase inhibition by naphthoquinones in cell-free assays. Naphthazarin (0.1 µM) decreased degranulation induced by IgE/antigen but not A23187, suggesting a mechanism upstream of the calcium increase, unlike diospyrin (10 µM) that reduced degranulation in A23187-stimulated cells. Naphthoquinones were weak hyaluronidase inhibitors, but all inhibited soybean lipoxidase with the most lipophilic diospyrin, diosquinone and menadione being the most potent, thus suggesting a mechanism of competition with natural lipophilic substrates. Menadione was the only naphthoquinone reducing leukotriene C4 production, with a maximal effect at 5 µM. This work expands the current knowledge on the biological properties of naphthoquinones, highlighting naphthazarin, diospyrin and menadione as potential lead compounds for structural modification in the process of improving and developing novel anti-allergic drugs. PMID:24587235

  2. In vitro immunological degranulation of human basophils is modulated by lung histamine and Apis mellifica.

    PubMed Central

    Poitevin, B; Davenas, E; Benveniste, J

    1988-01-01

    1. The effect of high dilutions of two homeopathic drugs Lung histamine (Lung his) and Apis mellifica (Apis mel) used for the treatment of allergic diseases has been assessed on in vitro human basophil degranulation. Experiments were conducted blind. 2. Basophil degranulation induced by 1.66 X 10(-9) M anti-IgE antibody was significantly inhibited in the presence of 5 Lung his (5th centesimal dilution of Lung his) and 15 Lung his (15th centesimal dilution of Lung his) by 28.8% and 28.6% respectively and by 65.8% in the presence of 9 Apis mel (9th centesimal dilution of Apis mel). Basophil degranulation induced by 1.66 X 10(-16) to 1.66 X 10(-18) M anti-IgE antibody was also inhibited by high dilutions of Lung his and Apis mel with an inhibition of nearly 100% with 18 Lung his (18th centesimal dilution of Lung his) and 10 Apis mel (10th centesimal dilution of Apis mel). An alternance of inhibition, inactivity and stimulation was observed when basophils were incubated in the presence of serial dilutions of Lung his and Apis mel. 3. The investigation of the clinical efficacy of high dilutions of Lung his and Apis mel should be envisaged in allergic diseases in parallel with in vitro and ex vivo biological assays. PMID:3382588

  3. Quantifying psoralen in tissues by fluorescence: dosimetry for psoralen administration followed by ultraviolet A irradiation (PUVA) to block restenosis

    NASA Astrophysics Data System (ADS)

    Jacques, Steven L.; Buckley, Lisa A.; Prahl, Scott A.; Gregory, Kenton W.

    1994-07-01

    PUVA therapy may prove effective in preventing restenosis of vessels following balloon angioplasty to open vessels narrowed by atherosclerosis. The technique relies on the ability of PUVA (psoralen administration followed by ultraviolet A irradiation) to cause crosslinks and monoadducts that prevent cellular proliferation without causing cell death. Such PUVA treatment has been successful in controlling cutaneous cell proliferation of psoriasis. The efficacy of PUVA treatment depends on the drug concentration and the light dose. The amount of light delivered is easily modified to adapt to variations in the drug concentration if the drug levels in the vessel wall are known. This paper demonstrates the feasibility of assaying psoralen levels in tissues and in serum samples using psoralen fluorescence as an indictor.

  4. Serum- and glucocorticoid-inducible kinase SGK1 regulates reorganization of actin cytoskeleton in mast cells upon degranulation.

    PubMed

    Schmid, Evi; Gu, Shuchen; Yang, Wenting; Münzer, Patrick; Schaller, Martin; Lang, Florian; Stournaras, Christos; Shumilina, Ekaterina

    2013-01-01

    Aggregation of the high-affinity IgE receptor (FcεRI) on mast cells (MCs) causes MC degranulation, a process that involves cortical F-actin disassembly. Actin depolymerization may be triggered by increase of cytosolic Ca(2+). Entry of Ca(2+) through the Ca(2+) release-activated Ca(2+) (CRAC) channels is under powerful regulation by the serum- and glucocorticoid-inducible kinase SGK1. Moreover, FcεRI-dependent degranulation is decreased in SGK1-deficient (sgk1(-/-)) MCs. The present study addressed whether SGK1 is required for actin cytoskeleton rearrangement in MCs and whether modulation of actin architecture could underlie decreased degranulation of sgk1(-/-) MCs. Confirming previous results, release of β-hexosaminidase reflecting FcεRI-dependent degranulation was impaired in sgk1(-/-) MCs compared with sgk1(+/+) MCs. When CRAC channels were inhibited by 2-aminoethoxydiphenyl borate (2-APB; 50 μM), MC degranulation was strongly decreased in both sgk1(+/+) and sgk1(-/-) MCs and the difference between genotypes was abolished. Moreover, degranulation was impaired by actin-stabilizing (phallacidin) and enhanced by actin-disrupting (cytochalasin B) agents to a similar extent in sgk1(+/+) MCs and sgk1(-/-) MCs, implying a regulatory role of actin reorganization in this event. In line with this, measurements of monomeric (G) and filamentous (F) actin content by FACS analysis and Western blotting of detergent-soluble and -insoluble cell fractions indicated an increase of the G/F-actin ratio in sgk1(+/+) MCs but not in sgk1(-/-) MCs upon FcεRI ligation, an observation reflecting actin depolymerization. In sgk1(+/+) MCs, FcεRI-induced actin depolymerization was abolished by 2-APB. The observed actin reorganization was confirmed by confocal laser microscopic analysis. Our observations uncover SGK1-dependent Ca(2+) entry in mast cells as a novel mechanism regulating actin cytoskeleton.

  5. Small molecular antioxidants effectively protect from PUVA-induced oxidative stress responses underlying fibroblast senescence and photoaging.

    PubMed

    Briganti, Stefania; Wlaschek, Meinhard; Hinrichs, Christina; Bellei, Barbara; Flori, Enrica; Treiber, Nicolai; Iben, Sebastian; Picardo, Mauro; Scharffetter-Kochanek, Karin

    2008-09-01

    Exposure of human fibroblasts to 8-methoxypsoralen plus ultraviolet-A irradiation (PUVA) results in stress-induced cellular senescence in fibroblasts. We here studied the role of the antioxidant defense system in the accumulation of reactive oxygen species (ROS) and the effect of the antioxidants alpha-tocopherol, N-acetylcysteine, and alpha-lipoic acid on PUVA-induced cellular senescence. PUVA treatment induced an immediate and increasing generation of intracellular ROS. Supplementation of PUVA-treated fibroblasts with alpha-tocopherol (alpha-Toc), N-acetylcysteine (NAC), or alpha-lipoic acid (alpha-LA) abrogated the increased ROS generation and rescued fibroblasts from the ROS-dependent changes into the cellular senescence phenotype, such as cytoplasmic enlargement, enhanced expression of senescence-associated-beta-galactosidase and matrix-metalloproteinase-1, hallmarks of photoaging and intrinsic aging. PUVA treatment disrupted the integrity of cellular membranes and impaired homeostasis and function of the cellular antioxidant system with a significant decrease in glutathione and hydrogen peroxide-detoxifying enzymes activities. Supplementation with NAC, alpha-LA, and alpha-Toc counteracted these changes. Our data provide causal evidence that (i) oxidative stress due to an imbalance in the overall cellular antioxidant capacity contributes to the induction and maintenance of the PUVA-induced fibroblast senescence and that (ii) low molecular antioxidants protect effectively against these deleterious alterations.

  6. Bullous pemphigoid. Occurrence in a patient with mycosis fungoides receiving PUVA and topical nitrogen mustard therapy

    SciTech Connect

    Patterson, J.W.; Ali, M.; Murray, J.C.; Hazra, T.A.

    1985-04-01

    A 57-year-old woman with mycosis fungoides developed blisters within cutaneous plaques while receiving PUVA therapy and topical nitrogen mustard. Direct and indirect immunofluorescence studies showed the findings of bullous pemphigoid. Her bullous disease was controlled after cessation of these therapies and institution of prednisone and methotrexate. During the 5 months following completion of a course of electron-beam therapy, she has been free of the cutaneous manifestations of both diseases. Previous instances of PUVA-related pemphigoid have occurred in psoriatics. The role of ultraviolet light in the induction of pemphigoid is discussed, particularly with regard to its possible interaction with the altered skin of psoriasis or mycosis fungoides. Some of the rare cases of bullous mycosis fungoides might actually have represented ultraviolet-unmasked bullous pemphigoid.

  7. DNA damage in human skin fibroblasts exposed to UVA light used in clinical PUVA treatment

    SciTech Connect

    Bredberg, A.

    1981-06-01

    Human skin fibroblasts were irradiated with a clinically used UVA light source. The doses (1.1 and 3 J/cm2) were similar to those reaching the dermis during clinical PUVA treatment of psoriasis. DNA strand breaks, as determined by alkaline elution, were formed in a dose-dependent way and disappeared within 1 hr of postincubation at 37 degrees C. These findings have clinical implications since UVA-induced DNA damage may be accompanied by mutagenic and tumor promoting effects.

  8. Psoralen loaded liposomal nanocarriers for improved skin penetration and efficacy of topical PUVA in psoriasis.

    PubMed

    Doppalapudi, Sindhu; Jain, Anjali; Chopra, Dhiraj Kumar; Khan, Wahid

    2017-01-01

    Psoralen in combination with ultraviolet A radiation (PUVA) is an FDA recommended therapy for clinical application in the management of severe recalcitrant psoriasis. Psoralen acts by intercalation of DNA and upon exposure to UV-A, it forms monoadducts which in turn induce apoptosis. Poor skin deposition, weak percutaneous permeability of psoralen and adverse effects of severe burning, blisters, pigmentation associated with conventional topical psoralen vehicles hinders the therapeutic efficacy and safety of topical PUVA. The aim of the present study is to formulate psoralen loaded liposomal nanocarriers for enhanced skin penetration, safety and efficacy of topical PUVA in psoriasis. Two different liposomal compositions i.e., cationic liposomes composed of DC-Chol, cholesterol and anionic liposomes composed of egg lecithin, cholesterol, tetramyristoyl cardiolipin were prepared for the topical delivery of psoralen. Liposomal carriers were characterized with respect to size, zeta potential, entrapment efficiency, stability, in vitro drug release and in vivo studies. Both liposomes were prepared with particle size of nearly 100nm. Zeta potential and entrapment efficiency of cationic liposomes were +25.8mV, 75.12% and anionic liposomes were -28.5mV, 60.08% respectively. Liposomal dermal distribution demonstrated higher penetration of both liposomal carriers over solution. Similarly, skin permeation study indicated 5 fold increase in permeation of psoralen with liposomal carriers. Topical application of psoralen liposomal gels on imiquimod induced psoriatic plaque model reduced the symptoms of psoriasis and levels of key psoriatic cytokines such as tumor necrosis factor-α, IL-17 and IL-22. In conclusion, the developed liposomal carriers of psoralen were found to be promising and can find application for optimal safety and efficacy of topical PUVA in psoriasis.

  9. Quantitative analysis on PUVA-induced skin photodamages using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhai, Juan; Guo, Zhouyi; Liu, Zhiming; Xiong, Honglian; Zeng, Changchun; Jin, Ying

    2009-08-01

    Psoralen plus ultraviolet A radiation (PUVA) therapy is a very important clinical treatment of skin diseases such as vitiligo and psoriasis, but associated with an increased risk of skin photodamages especially photoaging. Since skin biopsy alters the original skin morphology and always requires an iatrogenic trauma, optical coherence tomography (OCT) appears to be a promising technique to study skin damage in vivo. In this study, the Balb/c mice had 8-methoxypsralen (8-MOP) treatment prior to UVA radiation was used as PUVA-induced photo-damaged modal. The OCT imaging of photo-damaged group (modal) and normal group (control) in vivo was obtained of mice dorsal skin at 0, 24, 48, 72 hours after irradiation respectively. And then the results were quantitatively analyzed combined with histological information. The experimental results showed that, PUVA-induced photo-damaged skin had an increase in epidermal thickness (ET), a reduction of attenuation coefficient in OCT images signal, and an increase in brightness of the epidermis layer compared with the control group. In conclusion, noninvasive high-resolution imaging techniques such as OCT may be a promising tool for photobiological studies aimed at assessing photo-damage and repair processes in vivo. It can be used to quantitative analysis of changes in photo-damaged skin, such as the ET and collagen in dermis, provides a theoretical basis for treatment and prevention of skin photodamages.

  10. Psoriasis, PUVA, and skin cancer--molecular epidemiology: the curious question of T-->A transversions.

    PubMed

    Peritz, A E; Gasparro, F P

    1999-09-01

    Photochemotherapy with 8-methoxypsoralen and long wavelength ultraviolet radiation (PUVA) is commonly used to treat psoriasis and vitiligo. These vastly different diseases respond to the therapy by different mechanisms even though the immediate effects of the therapy - photoadduct formation - is the same for both. Because psoriasis is not cured by PUVA, patients receive many treatments over their lifetime and develop a significant risk for the development of skin cancers (primarily squamous cell carcinomas). In this review the basic aspects of psoralen photobiology are reviewed briefly. In addition the impact of the analysis of mutations in the tumor suppressor gene, p53, are summarized. An unexpected mutation spectrum (very few T-->A transversions and frequent UVB signature C-->T transitions) suggest that effects other than direct DNA photoadduct formation may be at play. The roles of reactive oxygen species-induced base changes as well as other clastogenic factors are discussed. This analysis suggests that it may be possible to improve the therapeutic efficacy of PUVA by a careful evaluation of the mode of delivery.

  11. The mitochondrial effects of novel apoptogenic molecules generated by psoralen photolysis as a crucial mechanism in PUVA therapy.

    PubMed

    Caffieri, Sergio; Di Lisa, Fabio; Bolesani, Federico; Facco, Monica; Semenzato, Gianpietro; Dall'Acqua, Francesco; Canton, Marcella

    2007-06-01

    The generation of photoproducts of psoralen (POPs) might be relevant in cell death induced by psoralen plus UVA, namely PUVA, which is a recognized effective treatment for cutaneous T-cell lymphoma, chronic graft-versus-host disease, and psoriasis. We investigated the occurrence of POP-induced cell death and the underlying mechanisms. POPs were produced by irradiating a psoralen solution with UVA. Jurkat cells treated in the dark with these mixtures died mainly through an apoptotic mechanism. POPs were separated by high-performance liquid chromatography (HPLC), and cells were added with each of these fractions. A total of 2 dimers of psoralen and 6-formyl-7-hydroxycoumarin (FHC) were identified in the apoptogenic fractions. Apoptosis was preceded by mitochondrial dysfunction caused by the opening of the mitochondrial permeability transition pore (PTP). In fact, both mitochondrial depolarization and cell death were prevented by the PTP inhibitor cyclosporin A (CsA). PTP opening was also documented in isolated mitochondria added with POP, suggesting that apoptosis is caused by a direct effect of POP on mitochondria. In fact, FHC alone induced PTP opening and CsA-inhibitable cell death of Jurkat cells, whereas nontransformed T lymphocytes were resistant. Along with identifying novel apoptogenic molecules, the present results indicate that POP generation directs transformed cells to apoptosis.

  12. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-07-01

    Monitoring a degranulation process in a live mast cell is a quite important issue in immunology and pharmacology. Because the size of a granule is normally much smaller than the resolution limit of an optical microscope system, there is no direct real-time live cell imaging technique for observing degranulation processes except for fluorescence imaging techniques. In this research, we propose optical quantitative phase microscopy (QPM) as a new observation tool to study degranulation processes in a live mast cell without any fluorescence labeling. We measure the cell volumes and the cross sectional profiles (x-z plane) of an RBL-2H3 cell and a HeLa cell, before and after they are exposed to calcium ionophore A23187 and silver nanoparticles (AgNPs). We verify that the volume and the cross sectional line profile of the RBL-2H3 cell were changed significantly when it was exposed to A23187. When 50 μg/mL of AgNP is used instead of A23187, the measurements of cell volume and cross sectional profiles indicate that RBL-2H3 cells also follow degranulation processes. Degranulation processes for these cells are verified by monitoring the increase of intracellular calcium ([Ca2+]i) and histamine with fluorescent methods.

  13. Inhibitory effects of geranium essential oil and its major component, citronellol, on degranulation and cytokine production by mast cells.

    PubMed

    Kobayashi, Yuko; Sato, Harumi; Yorita, Mika; Nakayama, Hiroto; Miyazato, Hironari; Sugimoto, Keiichiro; Jippo, Tomoko

    2016-06-01

    We investigated the effects of geranium essential oil (GEO) on anaphylaxis. GEO can exert antioxidant and anti-inflammatory effects, but its roles in allergic reactions are incompletely understood. Here, we used mouse cells to show that GEO inhibited the degranulation of cultured mast cells (CMCs). Citronellol is the major component of GEO and inhibited CMC degranulation. The l-enantiomer of citronellol more effectively suppressed CMC degranulation than did d-citronellol. We also examined whether citronellol could inhibit the immunoglobulin (Ig) E-induced production of tumor necrosis factor (TNF)-α. Treatment with various concentrations of citronellol before CMC activation with IgE significantly inhibited the induction of TNF-α in a dose-dependent manner. Mechanistically, citronellol suppressed the phosphorylation of mitogen-activated protein kinase (ERK), which is critical for ERK activation and the production of inflammatory cytokines in mast cells. These findings suggest that citronellol may represent a candidate compound for the effective treatment of allergic diseases.

  14. CD11b/CD18 (Mac-1) is required for degranulation of human eosinophils induced by human recombinant granulocyte-macrophage colony-stimulating factor and platelet-activating factor.

    PubMed

    Horie, S; Kita, H

    1994-06-01

    Recent evidence suggests adhesion molecules play an important role in the function of leukocytes. Because human eosinophils are known to express beta 2 integrins, we hypothesized that these adhesion molecules mediate the effector function of eosinophils. Normal human eosinophils incubated in albumin-coated polystyrene plates released granule protein and produced superoxide anion when stimulated with human recombinant granulocyte-macrophage CSF (rGM-CSF), platelet-activating factor (PAF), or PMA. Simultaneous monitoring of eosinophil adhesion and degranulation showed that degranulation was always preceded by cellular adhesion regardless of stimuli. Furthermore, eosinophil degranulation induced by human rGM-CSF and PAF was abolished in suspension culture of the cells when the cell suspensions were gently stirred. To identify the molecules involved in this adhesion-dependent degranulation, we have investigated the effects of mAbs (mAb) against beta 2 integrins. mAb reactive with CD18 markedly inhibited the eosinophil adhesion and degranulation induced by PAF and human rGM-CSF. mAb reactive with CD11b also moderately inhibited the adhesion and degranulation. In contrast, mAb reactive with CD11a slightly enhanced or showed no effect on the adhesion and degranulation by human rGM-CSF or PAF. Superoxide production induced by human rGM-CSF and PAF was also abolished by the treatment of cells with anti-CD18 mAb. mAb against CD11b and CD18 had little effect on degranulation and superoxide production induced by PMA. These results indicate that CD11b/CD18 (Mac-1)-dependent cellular adhesion plays an important role in the degranulation and superoxide production of eosinophils induced by human rGM-CSF and PAF, and that these mechanisms may be employed in vivo where eosinophils contact with stromal cells and/or proteins.

  15. Fyn kinase controls Fc{epsilon}RI receptor-operated calcium entry necessary for full degranulation in mast cells

    SciTech Connect

    Sanchez-Miranda, Elizabeth; Ibarra-Sanchez, Alfredo; Gonzalez-Espinosa, Claudia

    2010-01-22

    IgE-antigen-dependent crosslinking of the high affinity IgE receptor (Fc{epsilon}RI) on mast cells leads to degranulation, leukotriene synthesis and cytokine production. Calcium (Ca{sup 2+}) mobilization is a sine qua non requisite for degranulation, allowing the rapid secretion of stored pro-inflammatory mediators responsible for allergy symptoms. Fyn is a Src-family kinase that positively controls Fc{epsilon}RI-induced mast cell degranulation. However, our understanding of the mechanism connecting Fyn activation to secretion of pre-synthesized mediators is very limited. We analyzed Fc{epsilon}RI-dependent Ca{sup 2+} mobilization in bone marrow-derived mast cells (BMMCs) differentiated from WT and Fyn -/- knock out mice. Fyn -/- BMMCs showed a marked defect in extracellular Ca{sup 2+} influx after Fc{epsilon}RI crosslinking but not after thapsigargin addition. High concentrations of Gadolinium (Gd{sup 3+}) partially blocked Fc{epsilon}RI-induced Ca{sup 2+} influx in WT cells but, in contrast, completely inhibited Ca{sup 2+} mobilization in Fyn -/- cells. Low concentrations of an inhibitor of the canonical transient receptor potential (TRPC) Ca{sup 2+} channels (2-aminoethoxyphenyl-borane, 2-APB) blocked Fc{epsilon}RI-induced maximal Ca{sup 2+} rise in WT but not in Fyn -/- cells. Ca{sup 2+} entry through Fyn-controlled, 2-APB sensitive channels was found to be important for full degranulation and IL-2 mRNA accumulation in WT cells. Immunoprecipitation assays showed that Fyn kinase interacts with TRPC 3/6/7 channels after IgE-antigen stimulation, but its association is not related to protein tyrosine phosphorylation. Results indicate Fyn kinase mediates the receptor-dependent activation of TRPC channels that contribute to degranulation in Fc{epsilon}RI-stimulated mast cells.

  16. Low-dose psoralen and UVA (PUVA) therapy-enhanced arterial shrinkage after balloon angioplasty in rabbits

    NASA Astrophysics Data System (ADS)

    Perree, Jop; van Leeuwen, Ton G. J. M.; Velema, Evelyn; Borst, Cornelius

    1998-07-01

    Restenosis after balloon angioplasty is caused by both intimal hyperplasia and arterial shrinkage (constrictive remodeling). Previous studies have indicated the inhibitory effect of photodynamic therapy on intimal hyperplasia development after angioplasty. The potential of a photoactivation regime (Psoralen + UVA irradiation: PUVA), which does not cause unwanted systemic side effects, for the prevention of both intimal hyperplasia formation and constrictive remodeling following balloon dilation was explored in the present study. In the rabbit iliac artery, balloon dilation followed by PUVA- therapy at a radiant exposure of 1 J/cm2 was performed (n equals 10). Control balloon dilation was performed in the contralateral arteries (n equals 10). After 4 weeks of survival, angiographic lumen renarrowing was determined in terms of intimal hyperplasia and constrictive remodeling. Late loss, but not intimal hyperplasia, was significantly larger in the PUVA group as compared to the control group (p less than 0.05). This difference in angiographic lumen loss can only be attributed to the difference in constrictive remodeling (arterial shrinkage). Thus, PUVA-therapy did not prevent intimal hyperplasia following balloon dilation. PUVA-therapy even enhanced luminal narrowing by augmented constrictive arterial remodeling.

  17. Assessment of Anticarcinogenic Potential of Vitex trifolia and Triticum aestivum Linn by In Vitro Rat Liver Microsomal Degranulation

    PubMed Central

    Mathankumar, Marimuthu; Tamizhselvi, Ramasamy; Manickam, Venkatraman; Purohit, Gaurav

    2015-01-01

    Objective: The main objective of this preliminary study is to confirm the synergistic anticarcinogenic potential of Vitex trifolia and Triticum aestivum ethanolic extracts. Materials and Methods: Rat hepatic microsomal degranulation is a short - term technique that has been used for the detection of potential chemical carcinogens, in vitro. The present study has been carried out to study the inhibition of ribosome- membrane disruption against 3, 8-Diamino-5-ethyl-6-pheylphenanthridinium bromide (EB), as the degranulating agent, by measuring the RNA/protein ratios of microsomal membranes in the presence or absence of V.trifolia and T. aestivum extracts. These two extracts were further evaluated for cytotoxic effect in HCT 116 and A549 cell lines. Results: V. trifolia and T. aestivum protects hepatic microsomes against the degranulatory attack by the carcinogen EB showed a significant reduction in the proliferation of the HCT 116 and A549 cancer cell lines. Conclusion: The ethanolic extracts of the plants, V. trifolia and T. aestivum individually possessed anti-degranulatory potential. Importantly they act synergistically, possess appreciable anticarcinogenic properties, based on their ability to inhibit EB induced liver microsomal degranulation. Further these extracts inhibit cell proliferation of cancer cell lines. PMID:26862271

  18. SNEV(Prp19/PSO4) deficiency increases PUVA-induced senescence in mouse skin.

    PubMed

    Monteforte, Rossella; Beilhack, Georg F; Grausenburger, Reinhard; Mayerhofer, Benjamin; Bittner, Reginald; Grillari-Voglauer, Regina; Sibilia, Maria; Dellago, Hanna; Tschachler, Erwin; Gruber, Florian; Grillari, Johannes

    2016-03-01

    Senescent cells accumulate during ageing in various tissues and contribute to organismal ageing. However, factors that are involved in the induction of senescence in vivo are still not well understood. SNEV(P) (rp19/) (PSO) (4) is a multifaceted protein, known to be involved in DNA damage repair and senescence, albeit only in vitro. In this study, we used heterozygous SNEV(+/-) mice (SNEV-knockout results in early embryonic lethality) and wild-type littermate controls as a model to elucidate the role of SNEV(P) (rp19/) (PSO) (4) in DNA damage repair and senescence in vivo. We performed PUVA treatment as model system for potently inducing cellular senescence, consisting of 8-methoxypsoralen in combination with UVA on mouse skin to induce DNA damage and premature skin ageing. We show that SNEV(P) (rp19/) (PSO) (4) expression decreases during organismal ageing, while p16, a marker of ageing in vivo, increases. In response to PUVA treatment, we observed in the skin of both SNEV(P) (rp19/) (PSO) (4) and wild-type mice an increase in γ-H2AX levels, a DNA damage marker. In old SNEV(P) (rp19/) (PSO) (4) mice, this increase is accompanied by reduced epidermis thickening and increase in p16 and collagenase levels. Thus, the DNA damage response occurring in the mouse skin upon PUVA treatment is dependent on SNEV(P) (rp19/) (PSO) (4) expression and lower levels of SNEV(P) (rp19/) (PSO) (4) , as in old SNEV(+/-) mice, result in increase in cellular senescence and acceleration of premature skin ageing.

  19. Inhibitory Effect of Carotenoids on the Degranulation of Mast Cells via Suppression of Antigen-induced Aggregation of High Affinity IgE Receptors*

    PubMed Central

    Sakai, Shota; Sugawara, Tatsuya; Matsubara, Kiminori; Hirata, Takashi

    2009-01-01

    Carotenoids have been demonstrated to possess antioxidative and anti-inflammatory effects. However, there is no report that the effects of carotenoids on degranulation of mast cell is critical for type I allergy. In this study, we focused on the effect of carotenoids on antigen-induced degranulation of mast cells. Fucoxanthin, astaxanthin, zeaxanthin, and β-carotene significantly inhibited the antigen-induced release of β-hexosaminidase in rat basophilic leukemia 2H3 cells and mouse bone marrow-derived mast cells. Those carotenoids also inhibited antigen-induced aggregation of the high affinity IgE receptor (FcϵRI), which is the most upstream of the degranulating signals of mast cells. Furthermore, carotenoids inhibited FcϵRI-mediated intracellular signaling, such as phosphorylation of Lyn kinase and Fyn kinase. It suggests that the inhibitory effect of carotenoids on the degranulation of mast cells were mainly due to suppressing the aggregation of FcϵRI followed by intracellular signaling. In addition, those carotenoids inhibited antigen-induced translocation of FcϵRI to lipid rafts, which are known as platforms of the aggregation of FcϵRI. We assume that carotenoids may modulate the function of lipid rafts and inhibit the translocation of FcϵRI to lipid rafts. This is the first report that focused on the aggregation of FcϵRI to investigate the mechanism of the inhibitory effects on the degranulation of mast cells and evaluated the functional activity of carotenoids associated with lipid rafts. PMID:19700409

  20. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-02-01

    The use of AgNP is becoming more and more widespread in biomedical field. But compared with the promising bactericidal function, other physiological effects of AgNP on cells are relatively scant. In this research, we propose quantitative phase microscopy (QPM) as a new method to study the degranulation, and AgNP-induced RBL-2H3 cell degranulation is studied as well. Firstly, HeLa cells as the cell control and PBS as the solvent control, we measured the cell volume and cross section profile (x-z plane) with QPM. The results showed that the volume and cross section profile changed only the RBL-2H3 cells exposed to calcium ionophore A23187, which demonstrates the validity of QPM in degranulation research. Secondly, 50μg/mL of AgNP was used instead of A23187, and the measurement of cell volume and cross section profile was carried out again. RBL-2H3 cell volume increased immediately after AgNP was added, and cross section profile showed that the cell surface became granulated, but HeLa cell was lack of that effect. Phase images obviously indicated the RBL-2H3 cell deformation. Thirdly, stained with Fluo-3/AM, intracellular calcium Ca2+]i of single RBL-2H3 cell treated with AgNP was observed with fluorescent microscopy; incubated with AgNP for 20min, the supernatant of RBL-2H3 cells was collected and reacted with o-phthalaldehyde (OPA), then the fluorescent intensity of histamine-OPA complex was assayed with spectrofluorometer. The results of Ca2+]i and histamine increase showed that degranulation of AgNP-induced RBL-2H3 cell occurred. So, the cell volume was used as a parameter of degranulation in our study and AgNP-induced RBL-2H3 cells degranulation was confirmed by the cell volume increment, cross section profile change, and [Ca2+]i and histamine in supernatant increase.

  1. Ultrastructural modification of the plasma membrane in HUT 102 lymphoblasts by long-wave ultraviolet light, psoralen, and PUVA

    SciTech Connect

    Malinin, G.I.; Lo, H.K.; Hornicek, F.J.; Malinin, T.I. )

    1990-07-01

    Ultrastructural alterations of the plasma membrane in HUT 102 lymphoblasts were assessed after a 2-h interaction with a suprapharmacologic (15 micrograms/ml) concentration of 8-MOP, 2-h irradiation with UVA (2.1 mW/cm2), and the exposure of the HUT 102 cells to PUVA under the same conditions. The dark reaction of HUT cells with 8-MOP resulted in the disappearance of microvilli, the emergence of plasma-membrane-associated spherical bodies, formation of lamellar fungiform membrane evaginations, and, in approximately 1% of the cells, formation of uropods and cell capping. Except for uropod formation and cell capping, UVA has induced the same plasma-membrane alterations, and was more deleterious to structural cytoplasmic integrity than 8-MOP. Morphologic changes of the plasma membrane in PUVA-exposed cells tended to replicate structural alterations elicited independently during the dark reaction by suprapharmacologic 8-MOP concentrations. Partial retention of microvilli by cells after PUVA was the sole exception. In light of all available evidence we conclude that psoralen during the dark reactions interacts with plasma membrane lipids by as yet undisclosed mechanisms and that in addition to lipids, membrane proteins are also the primary target of the initial interaction of HUT 102 cells with psoralen during PUVA treatment.

  2. Contribution of engineered nanomaterials physicochemical properties to mast cell degranulation

    NASA Astrophysics Data System (ADS)

    Johnson, Monica M.; Mendoza, Ryan; Raghavendra, Achyut J.; Podila, Ramakrishna; Brown, Jared M.

    2017-03-01

    The rapid development of engineered nanomaterials (ENMs) has grown dramatically in the last decade, with increased use in consumer products, industrial materials, and nanomedicines. However, due to increased manufacturing, there is concern that human and environmental exposures may lead to adverse immune outcomes. Mast cells, central to the innate immune response, are one of the earliest sensors of environmental insult and have been shown to play a role in ENM-mediated immune responses. Our laboratory previously determined that mast cells are activated via a non-FcεRI mediated response following silver nanoparticle (Ag NP) exposure, which was dependent upon key physicochemical properties. Using bone marrow-derived mast cells (BMMCs), we tested the hypothesis that ENM physicochemical properties influence mast cell degranulation. Exposure to 13 physicochemically distinct ENMs caused a range of mast degranulation responses, with smaller sized Ag NPs (5 nm and 20 nm) causing the most dramatic response. Mast cell responses were dependent on ENMs physicochemical properties such as size, apparent surface area, and zeta potential. Surprisingly, minimal ENM cellular association by mast cells was not correlated with mast cell degranulation. This study suggests that a subset of ENMs may elicit an allergic response and contribute to the exacerbation of allergic diseases.

  3. Contribution of engineered nanomaterials physicochemical properties to mast cell degranulation

    PubMed Central

    Johnson, Monica M.; Mendoza, Ryan; Raghavendra, Achyut J.; Podila, Ramakrishna; Brown, Jared M.

    2017-01-01

    The rapid development of engineered nanomaterials (ENMs) has grown dramatically in the last decade, with increased use in consumer products, industrial materials, and nanomedicines. However, due to increased manufacturing, there is concern that human and environmental exposures may lead to adverse immune outcomes. Mast cells, central to the innate immune response, are one of the earliest sensors of environmental insult and have been shown to play a role in ENM-mediated immune responses. Our laboratory previously determined that mast cells are activated via a non-FcεRI mediated response following silver nanoparticle (Ag NP) exposure, which was dependent upon key physicochemical properties. Using bone marrow-derived mast cells (BMMCs), we tested the hypothesis that ENM physicochemical properties influence mast cell degranulation. Exposure to 13 physicochemically distinct ENMs caused a range of mast degranulation responses, with smaller sized Ag NPs (5 nm and 20 nm) causing the most dramatic response. Mast cell responses were dependent on ENMs physicochemical properties such as size, apparent surface area, and zeta potential. Surprisingly, minimal ENM cellular association by mast cells was not correlated with mast cell degranulation. This study suggests that a subset of ENMs may elicit an allergic response and contribute to the exacerbation of allergic diseases. PMID:28262689

  4. Singlet oxygen generation in PUVA therapy studied using electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Serrano-Pérez, Juan José; Olaso-González, Gloria; Merchán, Manuela; Serrano-Andrés, Luis

    2009-06-01

    The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin-orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet-triplet energy transfer process producing the singlet oxygen, and the reaction rates and lifetimes, the efficiency in the phototherapeutic action of the furocoumarin family is predicted as: khellin < 5-methoxypsoralen (5-MOP) < 8-methoxypsoralen (8-MOP) < psoralen < 4,5‧,8-trimethylpsoralen (TMP) < 3-carbethoxypsoralen (3-CPS), the latter being the most efficient photosensitizer and singlet oxygen generator.

  5. Serotonin signalling is crucial in the induction of PUVA-induced systemic suppression of delayed-type hypersensitivity but not local apoptosis or inflammation of the skin.

    PubMed

    Wolf, Peter; Byrne, Scott N; Limon-Flores, Alberto Y; Hoefler, Gerald; Ullrich, Stephen E

    2016-07-01

    Psoralen and UVA (PUVA) has immunosuppressive and proapoptotic effects, which are thought to be responsible alone or in combination for its therapeutic efficacy. However, the molecular mechanism by which PUVA mediates its effects is not well understood. Activation of the serotonin (5-hydroxytryptamine, 5-HT) pathway has been suggested to be involved in the modulation of T-cell responses and found to mediate UVB-induced immune suppression. In particular, the activation of the 5-HT2A receptor has been proposed as one mechanism responsible for UV-induced immune suppression. We therefore hypothesized that 5-HT may play a role in PUVA-induced effects. The model of systemic suppression of delayed-type hypersensitivity (DTH) to Candida albicans was used to study immune function after exposure of C3H and KIT(W) (-Sh/W-Sh) mice to a minimal inflammatory dose of topical PUVA. The intra-peritoneal injection of the 5-HT2 receptor antagonist ketanserin or cyproheptadine or an anti-5-HT antibody immediately before PUVA exposure entirely abrogated suppression of DTH but had no significant effect on inflammation, as measured by swelling and cellular infiltration of the skin, and apoptosis as determined by the number of sunburn cells in C3H mice. Importantly, the systemic injection of 5-HT recapitulated PUVA immune suppression of DTH but did not induce inflammation or apoptosis in the skin. KIT(W) (-Sh/W-Sh) mice (exhibiting myelopoietic abnormalities, including lack of 5-HT-containing mast cells) were resistant to PUVA-induced suppression of DTH but not local skin swelling. Thus, this points towards a crucial role of 5-HT signalling in PUVA-induced immune suppression but not inflammation or apoptosis in situ in the skin.

  6. [Environmental UV radiation levels for dosing PUVA-sol in Mexico].

    PubMed

    Castanedo-Cázares, Juan Pablo; Torres-Álvarez, Bertha; Ehnis-Pérez, Adriana; Alba-Barba, Isaura

    2013-01-01

    Introducción: la terapia PUVA-sol tiene como ventaja su disponibilidad y bajo costo. Sin embargo, su utilización es empírica. La finalidad del estudio es cuantificar la radiación solar UVA ambiental y sugerir una forma de administración en México. Métodos: se midió la radiación UV en el centro del país (22 °N, 101 °O, 1877 m) mediante radiometría terrestre de 2007 a 2011. Se registró la variación por hora, mes, nubosidad y transmisión a través de placas de silicato doméstico. Resultados: más del 75 % de la radiación UVA se registra entre las 9:00 y las 17:00 horas. La intensidad anual promedio mínima fue de 20 mW/cm(2) y la máxima de 25.4 mW/cm(2) (ANOVA, p < 0.001). El cálculo de irradiación UVA mensual durante el cenit bajo cielo despejado puede estimarse mediante la fórmula: 23.8 + 0.13 (mes) - 0.13 (mes - 6.5)(2), (r(2) = 0.95, p < 0.001). La placa común (3 mm) de silicato doméstico tiene una absorbancia UVB de 0.93 y una transmitancia UVA de 0.58. Conclusiones: es posible el empleo racional de PUVA-sol según los datos obtenidos. Es necesario aislar la radiación UVB y ajustar la dosis según la nubosidad, así como apegarse al protocolo de seguridad a fin de obtener beneficios y minimizar los efectos adversos.

  7. SNARE complex-mediated degranulation in mast cells.

    PubMed

    Woska, Joseph R; Gillespie, Marc E

    2012-04-01

    Mast cell function and dysregulation is important in the development and progression of allergic and autoimmune disease. Identifying novel proteins involved in mast cell function and disease progression is the first step in the design of new therapeutic strategies. Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are a family of proteins demonstrated to mediate the transport and fusion of secretory vesicles to the membrane in mast cells, leading to the subsequent release of the vesicle cargo through an exocytotic mechanism. The functional role[s] of specific SNARE family member complexes in mast cell degranulation has not been fully elucidated. Here, we review recent and historical data on the expression, formation and localization of various SNARE proteins and their complexes in murine and human mast cells. We summarize the functional data identifying the key SNARE family members that appear to participate in mast cell degranulation. Furthermore, we discuss the utilization of RNA interference (RNAi) methods to validate SNARE function and the use of siRNA as a therapeutic approach to the treatment of inflammatory disease. These studies provide an overview of the specific SNARE proteins and complexes that serve as novel targets for the development of new therapies to treat allergic and autoimmune disease.

  8. [Human basophil degranulation test. Results of a modified technic (I)].

    PubMed

    Román Pérez, F; Berlanga Cortés, J A; Urquiă, M; Guerra Pasadas, F; Peña Martínez, J

    1986-01-01

    The degranulation of human basophils towards antigenic substances, to which they must be previously sensitized as a result of the antigen-antibody union at the membrane level, is a phenomenon that has an important application complementing diagnosis of diseases mediated by the Gell and Coombs classification of Type I Hypersensitivity, on which the principle of Human Basophils Degranulation Test (HBDT) was based. An essential requirement is to be able to collect an adequate quantity of basophils, as well as the visualization by means of a technique of convenient stain. In this work, we show a modified HBDT technique for basophil granulocytes staining. A total of 33 HBDT was carried out on patients sensitive to grass pollen and/or Olea europea pollen and/or D. pteronyssinus, and as controls, HBDT was done on healthy individuals with negative clinical history. Basophil enrichemnt from the circulating blood sample was done by means of centrifugation in Percoll density gradients of 1072, 1076, 1080 and 1082, and we obtained a higher number of basophils with a density of 1080 at 400 Xg for 30 minutes. The cellular bottom was resuspended in 600 microliters of PBS. We employed lyophilized antigenic extracts from grass pollen, Olea europea and D. pteronyssinus, employing weight/volume concentration of 10(-4), 10(-5), 10(-6) and 10(-7). The optimum dilutions were 10(-5) for grass pollen and D. pteronyssinus.

  9. [Stereological analysis of the degranulation and the contraction of platelets. Application to the ultrastructural study of thrombin induced excretion in vitro].

    PubMed

    Bryon, P A; Lagarde, M; Dechavanne, M

    1975-12-01

    A stereological model, which provides quantitative information on the morphology of the platelet release reaction as isolated from platelet aggregation, was developed for the human platelets separated from blood by Mustard's procedure. Three morphologically defined spaces (granules, surface-connected canalicular system S.C.S., cytoplasm) were used to characterize platelet degranulation (with the variation of the volume density of the granules) and contraction (with the variation of the volume density of both granules and S.C.S.). This model was applied to the evaluation of ultrastructural changes associated with the thrombin-induced release reaction. Degranulation and contraction were associated in the platelets which had been allowed to release for 1,5 and 150 sec. Under conditions of the study, prostaglandins E1 (10(-7) M) inhibited both degranulation and contraction (p less than 0,001). Aspirin (10(-4) M) only inhibited contraction (p less than 0.01) and dibutyryl-AMPc (10(-4)) only inhibited granulation (p less than 0,001).

  10. Effects of cigarette smoke on degranulation and NO production by mast cells and epithelial cells

    PubMed Central

    Wei, Xiu M; Kim, Henry S; Kumar, Rakesh K; Heywood, Gavin J; Hunt, John E; McNeil, H Patrick; Thomas, Paul S

    2005-01-01

    Exhaled nitric oxide (eNO) is decreased by cigarette smoking. The hypothesis that oxides of nitrogen (NOX) in cigarette smoke solution (CSS) may exert a negative feedback mechanism upon NO release from epithelial (AEC, A549, and NHTBE) and basophilic cells (RBL-2H3) was tested in vitro. CSS inhibited both NO production and degranulation (measured as release of beta-hexosaminidase) in a dose-dependent manner from RBL-2H3 cells. Inhibition of NO production by CSS in AEC, A549, and NHTBE cells was also dose-dependent. In addition, CSS decreased expression of NOS mRNA and protein expression. The addition of NO inhibitors and scavengers did not, however, reverse the effects of CSS, nor did a NO donor (SNP) or nicotine mimic CSS. N-acetyl-cysteine, partially reversed the inhibition of beta-hexosaminidase release suggesting CSS may act via oxidative free radicals. Thus, some of the inhibitory effects of CSS appear to be via oxidative free radicals rather than a NOX -related negative feedback. PMID:16168067

  11. Piecemeal degranulation (PMD) morphology in feline circulating eosinophils.

    PubMed

    Fondati, A; Fondevila, D; Ferrer, L

    2003-10-01

    Buffy coat preparation from six cats with 600-4560 circulating eosinophils/microL was collected by either blood centrifugation or sedimentation, fixed in 2.5% glutaraldehyde, post-fixed in either 1% osmium or in 1.5% potassium ferrocyanide-reduced osmium, ultra-sectioned and examined by transmission electron microscopy. Ultrastructural changes of piecemeal degranulation (PMD), which is a mechanism of eosinophil granule contents release indicative of eosinophil activation, were observed in specific granules from all the samples examined. The spectrum of PMD included coarsening of the granule matrix, budding vesicles, fragmented granule cores and lucent granules. The number of presumably activated eosinophils with ultrastructural evidence of PMD did not correlate with the level of eosinophilia. The lack of correlation suggested that, analogously with humans, blood eosinophil count might not represent the best criterion to evaluate the contribution of eosinophils to tissue damage in certain feline eosinophil-associated diseases.

  12. Effects of in vitro UVA irradiation and PUVA treatment on membrane fatty acids and activities of antioxidant enzymes in human keratinocytes

    SciTech Connect

    Punnonen, K.; Jansen, C.T.; Puntala, A.; Ahotupa, M. )

    1991-02-01

    Human Keratinocytes (NCTC 2544) in culture were exposed to either plain ultraviolet A (UVA) irradiation or to 8-methoxypsoralen plus UVA (PUVA) treatment. Lipid peroxidation, activities of antioxidant enzymes, and percentage amounts of 14C-arachidonic acid in various cellular lipid subclasses and in the culture medium were measured. Both UVA irradiation and PUVA treatment induced significant changes in the distribution of arachidonic acid and increased the liberation of arachidonic acid from membrane phospholipids. At 24 h after either UVA irradiation or PUVA treatment the formation of thiobarbituric acid reactive material was significantly increased, whereas the amount of conjugated dienes was unaffected. The activities of the antioxidant enzymes, catalase and superoxide dismutase, were already significantly decreased at 0.5 h after UVA irradiation or PUVA treatment. The enzyme activities were partially restored during the following 24 h incubation. From the present study, we suggest that in keratinocytes both plain UVA irradiation and PUVA treatment induce changes in the distribution of membrane fatty acids and cause an impairment in the enzymic defense system against oxidative stress.

  13. Psoriatic microangiopathy modifications induced by PUVA and etretinate therapy. A nail-fold capillary microscopic study.

    PubMed

    Trevisan, G; Magaton Rizzi, G; Dal Canton, M

    1989-01-01

    Histological and capillaroscopy alterations of capillary circulation in psoriasis are well known: the most common of them are the increase of "minor dystrophies", the higher haematic flux in the psoriatic plaques and the abnormal visibility of the venous subpapillary plexus (in arthropathic less than 65-year-old patients). The predisposition of psoriatic patients to a vascular damage has often been stressed in literature. In the present study, we have evaluated the effects of systemic etretinate or PUVA therapy on capillary functions. We examined the nail-folds of 30 patients (ranging 15-64 years) affected by diffuse psoriasis for less than three years. This study has been performed by using a Leitz capillary microscopy. We evaluated the percentage of capillary minor dystrophies (type I-IV) and the flow rate before and after 1 month of treatment. These parameters were assessed by means of a 1-4 rating scale. Our results underline that a significant percentage of 1st type dystrophies is a prognostic rather than a diagnostic parameter in the capillaroscopic evaluation of psoriasis.

  14. Inhibitory effect of heat-killed Lactobacillus strain on immunoglobulin E-mediated degranulation and late-phase immune reactions of mouse bone marrow-derived mast cells.

    PubMed

    Kawahara, Takeshi

    2010-12-01

    This study investigated the in vitro effect of Lactobacillus strains, a major group of probiotic lactic acid bacteria, on immunoglobulin E (IgE)- and antigen-induced mast cell degranulation and subsequent gene expression. Bone marrow-derived mast cells (BMMCs) from DBA/2 mice were cultured with heat-killed Lactobacillus strains for 24 h. Some strains significantly inhibited IgE- and antigen-induced β-hexosaminidase release from BMMCs. Furthermore, Lactobacillus reuteri NBRC 15892, which exhibited the strongest inhibitory activity, significantly reduced the elevated interleukin (IL)-4, IL-13, tumor necrosis factor-α, and cyclooxygenase-2 expression levels that was induced by 1-2 h of stimulation with IgE and antigens. The suppressive effect of NBRC 15892 strain on BMMC degranulation was significantly reduced in the presence of a toll-like receptor (TLR)2-neutralizing antibody. In addition, downregulation of cell surface FcεRIα expression was observed after 6 h of NBRC 15892 treatment. These results suggest that some Lactobacillus strains inhibited IgE-mediated mast cell degranulation and subsequent late-phase reactions involving mast cells via a TLR2-dependent mechanism with FcεRIα downregulation.

  15. CC chemokines induce neutrophils to chemotaxis, degranulation, and alpha-defensin release.

    PubMed

    Jan, Ming-Shiou; Huang, Yi-Hsien; Shieh, Biehuoy; Teng, Ru-Hsiu; Yan, Yao-Pei; Lee, Yuan-Ti; Liao, Ko-Kaung; Li, Ching

    2006-01-01

    We have previously shown that a Taiwanese cohort of HIV-uninfected individuals was associated with the significantly elevated levels of serum beta-chemokines, macrophage inflammatory protein (MIP-1)-alpha and MIP-beta, and RANTES. In the present study, we report that the members of this cohort have significantly greater numbers of lower buoyant-density neutrophils in their blood, which leads to further investigation of the effects of beta-chemokines on neutrophils. By electron and confocal microscopic techniques and FACScan, the results demonstrated that MIP-1alpha, MIP-beta, and/or RANTES readily activated the cells to release a large quantity of alpha-defensins in vitro through the degranulation process, which was the cause of low-buoyant-density neutrophil production. The purified neutrophils underwent chemotaxis and increased phagocytic capability when beta-chemokines were present. Only when using all 3 neutralizing antibodies for CCR1, CCR3, and CCR5 could the chemotaxis of neutrophils be inhibited completely, suggesting that these receptors are involved in transducing activating signals. Because neutrophils are the most abundant white blood cells that can be activated simultaneously to release alpha-defensins and because these proteins are antiviral, including anti-HIV, our results support the hypothesis that in addition to beta-chemokines, the innate immunity of the cohort plays a role in inhibiting the transmission of HIV.

  16. Real-time imaging of mast cell degranulation in vitro and in vivo.

    PubMed

    Horiguchi, Kayo; Yoshikawa, Soichiro; Saito, Asuka; Haddad, Salma; Ohta, Takuya; Miyake, Kensuke; Yamanishi, Yoshinori; Karasuyama, Hajime

    2016-10-21

    Mast cells undergo degranulation in response to various stimuli and rapidly release pre-formed mediators present in secretory granules, leading to immediate-type allergic reactions. Mast cell degranulation is commonly detected and quantified in vitro by measuring histamine or β-hexosaminidase released to culture medium. However, this type of assay cannot monitor degranulation of individual cells in real time, and it is not suitable for in vivo detection of degranulation. At the aim of real time imaging of mast cell degranulation at single cell level, we here developed a fluorescent protein-based indicator of degranulation, designated immuno-pHluorin (impH). When expressed in mast cells, impH is located in the membrane of secretory granules and non-fluorescent under homeostatic conditions while it turns fluorescent following degranulation, due to the pH change inside of granules during exocytosis. impH enabled us to detect polarized degranulation within one single cell when mast cells were stimulated via the small area of cell surface. Transplantation of impH-expressing mast cells into mast cell-deficient mice demonstrated that impH could function as a real-time indicator of degranulation in vivo. Thus, impH is a useful tool for imaging of mast cell activation and degranulation in vitro and in vivo, and may be applied for screening of reagents regulating mast cell degranulation.

  17. Cycloartenyl ferulate, a component of rice bran oil-derived gamma-oryzanol, attenuates mast cell degranulation.

    PubMed

    Oka, T; Fujimoto, M; Nagasaka, R; Ushio, H; Hori, M; Ozaki, H

    2010-02-01

    IgE-targeting therapy could provide significant progress in the treatment of allergic inflammation. In this study, we examined the effect of cycloartenyl ferulate (cycloartenol ferulic acid ester; CAF), a natural product from rice bran oil-derived gamma-oryzanol, on allergic reaction. When CAF and gamma-oryzanol were injected intradermally with anti-DNP IgE into the dorsal skin of rats, the passive cutaneous anaphylaxis reaction induced by DNP-HSA was attenuated. CAF and gamma-oryzanol also inhibited the degranulation of DNP-IgE sensitized RBL-2H3 mast cells stimulated with anti-DNP-HSA. IgE conjugated with CAF could not be detected by anti-IgE antibody in the ELISA analysis. Although incubation of IgE with CAF did not decrease the amount of IgE, it was possible to precipitate IgE by centrifugation. These results demonstrate that CAF captures IgE, prevents it from binding to FcepsilonRI, and attenuates mast cell degranulation.

  18. Involvement of leukotriene B4 receptor 1 signaling in platelet-activating factor-mediated neutrophil degranulation and chemotaxis.

    PubMed

    Gaudreault, Eric; Stankova, Jana; Rola-Pleszczynski, Marek

    2005-01-01

    Platelet-activating factor (PAF) is a potent lipid mediator of inflammation that can act on human neutrophils. When neutrophils are stimulated with PAF at concentrations greater than 10 nM, a double peak of intracellular calcium mobilization is observed. The second calcium peak observed in PAF-treated neutrophils has already been suggested to come from the production of endogenous leukotriene B4 (LTB4). Here we demonstrate the involvement of endogenous LTB4 production and subsequent activation of the high affinity LTB4 receptor (BLT1) in this second calcium mobilization peak observed after stimulation with PAF. We also show that the second, but not the first peak, could be desensitized by prior exposure to LTB4. Moreover, when neutrophils were pre-treated with pharmacological inhibitors of LTB4 production or with the specific BLT1 antagonist, U75302, PAF-mediated neutrophil degranulation was inhibited by more than 50%. On the other hand, pre-treating neutrophils with the PAF receptor specific antagonist (WEB2086) did not prevent any LTB4-induced degranulation. Also, when human neutrophils were pre-treated with U75302, PAF-mediated chemotaxis was reduced by more than 60%. These data indicate the involvement of BLT1 signaling in PAF-mediated neutrophil activities.

  19. Nucleoside 5′-O-monophosphorothioates as modulators of the P2Y14 receptor and mast cell degranulation

    PubMed Central

    Gendaszewska-Darmach, Edyta; Węgłowska, Edyta; Walczak-Drzewiecka, Aurelia; Karaś, Kaja

    2016-01-01

    Mast cells (MCs) are long-lived resident cells known for their substantial role in antigen-induced anaphylaxis and other immunoglobulin E-mediated allergic reactions as well as tumor promotion. MCs' activation results in the release of pro-inflammatory factors such as histamine, tryptase, tumor necrosis factor or carboxypeptidase A stored in secretory granules. IgE-dependent hypersensitivity has been thought to be the major pathway mediating degranulation of mast cells, but the P2Y14 nucleotide receptor activated by UDP-glucose (UDPG) may also enhance this process. In this study we identified thymidine 5'-O-monophosphorothioate (TMPS) as a molecule inhibiting UDPG-induced degranulation in a rat mast cell line (RBL-2H3). Additionally, TMPS diminished UDPG-evoked intracellular calcium mobilization in a stable HEK293T cell line overexpressing the P2Y14 receptor. Therefore, we demonstrate that the use of thymidine 5'-O-monophosphorothioate might be a novel anti-inflammatory approach based on preventingmast cell activation. PMID:27732965

  20. Sulfur mustard primes human neutrophils for increased degranulation and stimulates cytokine release via TRPM2/p38 MAPK signaling

    SciTech Connect

    Ham, Hwa-Yong; Hong, Chang-Won; Lee, Si-Nae; Kwon, Min-Soo; Kim, Yeon-Ja; Song, Dong-Keun

    2012-01-01

    Sulfur mustard (2,2′-bis-chloroethyl-sulfide; SM) has been a military threat since the World War I. The emerging threat of bioterrorism makes SM a major threat not only to military but also to civilian world. SM injury elicits an inflammatory response characterized by infiltration of neutrophils. Although SM was reported to prime neutrophils, the mechanism has not been identified yet. In the present study, we investigated the mechanism of SM-induced priming in human neutrophils. SM increased [Ca{sup 2+}]{sub i} in human neutrophils in a concentration-dependent fashion. Transient receptor potential melastatin (TRPM) 2 inhibitors (clotrimazole, econazole and flufenamic acid) and silencing of TRPM2 by shRNA attenuated SM-induced [Ca{sup 2+}]{sub i} increase. SM primed degranulation of azurophil and specific granules in response to activation by fMLP as previously reported. SB203580, an inhibitor of p38 MAPK, inhibited SM-induced priming. Neither PD98057, an ERK inhibitor, nor SP600215, a JNK inhibitor, inhibited SM-induced priming. In addition, SM enhanced phosphorylation of NF-kB p65 and release of TNF-α, interleukin (IL)-6 and IL-8. SB203580 inhibited SM-induced NF-kB phosphorylation and cytokine release. These results suggest the involvement of TRPM2/p38 MAPK pathway in SM-induced priming and cytokines release in neutrophils. -- Highlights: ► SM increased [Ca{sup 2+}]{sub i} in human neutrophils through TPRM2-mediated calcium influx. ► SM primed degranulation of azurophil and specific granules. ► SM enhanced p38 MAPK and NF-κB p65 phosphorylation in human neutrophils. ► SM enhanced release of TNF-α, interleukin (IL)-6 and IL-8 from human neutrophils. ► SB203580 inhibited SM-induced priming, NF-κB p65 phosphorylation and cytokine release.

  1. Degranulation Response in Cytotoxic Rat Lymphocytes Measured with a Novel CD107a Antibody

    PubMed Central

    Sudworth, Amanda; Dai, Ke-Zheng; Vaage, John T.; Kveberg, Lise

    2016-01-01

    Measuring degranulation through CD107a expression has become an advantageous tool for testing the functional capacity of cytotoxic cells. Such functional studies have been hampered in the rat by the lack of a suitable anti-rat CD107a antibody. In this study, we report a novel hybridoma generated by immunizing Armenian inbred hamsters with transfected Chinese hamster ovary cells expressing CD107a. The SIM1 clone exhibited specific reactivity with CD107a and measured degranulation from natural killer (NK) cells stimulated with target cells or mAb crosslinking of their activating receptors. Degranulation in IL-2-activated NK cells could also be measured, when using low effector to target ratios. SIM1 also stained activated CD8, but not CD4 T cells. This report characterizes the degranulation response in cytotoxic rat cells with a new antibody against rat CD107a. PMID:28003815

  2. Single-Cell Analysis of Mast Cell Degranulation Induced by Airway Smooth Muscle-Secreted Chemokines

    PubMed Central

    Manning, Benjamin M.; Meyer, Audrey F.; Gruba, Sarah M.; Haynes, Christy L.

    2015-01-01

    Background Asthma is a chronic inflammatory disease characterized by narrowed airways, bronchial hyper-responsiveness, mucus hyper-secretion, and airway remodeling. Mast cell (MC) infiltration into airway smooth muscle (ASM) is a defining feature of asthma, and ASM regulates the inflammatory response by secreting chemokines, including CXCL10 and CCL5. Single cell analysis offers a unique approach to study specific cellular signaling interactions within large and complex signaling networks such as the inflammatory microenvironment in asthma. Methods Carbon fiber microelectrode amperometry was used to study the effects of ASM–secreted chemokines on mouse peritoneal MC degranulation. Results MC degranulation in response to CXCL10 and CCL5 was monitored at the single cell level. Relative to IgE-mediated degranulation, CXCL10- and CCL5-stimulated MCs released a decreased amount of serotonin per granule with fewer release events per cell. Decreased serotonin released per granule was correlated with increased spike half-width and rise-time values. Conclusions MCs are directly activated with ASM-associated chemokines. CXCL10 and CCL5 induce less robust MC degranulation compared to IgE- and A23187-stimulation. The kinetics of MC degranulation are signaling pathway-dependent, suggesting a biophysical mechanism of regulated degranulation that incorporates control over granule trafficking, transport, and docking machinery. General Significance The biophysical mechanisms, including variations in number of exocytotic release events, serotonin released per granule, and the membrane kinetics of exocytosis that underlie MC degranulation in response to CXCL10 and CCL5 were characterized at the single cell level. These findings clarify the function of ASM-derived chemokines as instigators of MC degranulation relative to classical mechanisms of MC stimulation. PMID:25986989

  3. Neuropeptides degranulate serous cells of ferret tracheal glands

    SciTech Connect

    Gashi, A.A.; Borson, D.B.; Finkbeiner, W.E.; Nadel, J.A.; Basbaum, C.B.

    1986-08-01

    To determine whether serous or mucous cells in tracheal submucosal glands respond to the neuropeptides substance P (SP) and vasoactive intestinal peptide (VIP). The authors studied the peptide-induced changes in gland cell morphology accompanying release of TVSO4-labeled macromolecules from tracheal explants of ferrets. Explants were labeled for 1 h in medium containing TVSO4 and washed for 3.5 additional hours. Base-line secretion in the absence of drugs declined between 1.5 and 3.5 h after the pulse. Between 2.5 and 3.5 h, the average percent change in counts per minute recovered per sample period was not significantly different from zero. Substance P and VIP added 4 h after labeling each increased greatly the release of TVSO4-labeled macromolecules above base line. Bethanechol, a muscarinic-cholinergic agonist, increased secretion by an average of 142% above base line. Light and electron microscopy of the control tissues showed glands with narrow lumens and numerous secretory granules. Glands treated with SP or VIP had enlarged lumens and the serous cells were markedly degranulated. These phenomena were documented by morphometry and suggest that SP and VIP cause secretion from glands at least partially by stimulating exocytosis from serous cells.

  4. Central role of mitochondria and p53 in PUVA-induced apoptosis in human keratinocytes cell line NCTC-2544

    SciTech Connect

    Viola, Giampietro Fortunato, Elena; Cecconet, Laura; Del Giudice, Laura; Dall'Acqua, Francesco; Basso, Giuseppe

    2008-02-15

    Despite strong evidence concerning the high efficiency of PUVA therapy (psoralen plus UVA light), its mechanism of action has not yet been fully elucidated. In this study, we have evaluated in a cell line of human keratinocytes (NCTC-2544) the effects of two linear psoralen derivatives, 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP), that are widely used in PUVA therapy and two angular derivatives, Angelicin (ANG) and 4,6,4'-trymetyl angelicin (TMA). All derivatives photoinduce cellular death, TMA being the most active compound. The cell cycle analysis showed that the four derivatives induce, 24 h after irradiation, a cell cycle arrest in G1 phase later followed by massive apoptosis. The G1 arrest is correlated to an increase in the expression of p21{sup Waf1/Cip1}, a protein associated with the cell cycle block and apoptosis. Furthermore, treatment of NCTC-2544 resulted in p53 activation by 5-MOP, 8-MOP, and ANG but not TMA and its phosphorylation at serine-15. The levels of p21{sup Waf1/Cip1} paralleled p53 protein staining pattern suggesting that p53 activation correlated with p21{sup Waf1/Cip1} induction. Simultaneous to p53 activation, psoralens induced mitochondrial depolarization, cytochrome c release, mitochondrial production of reactive oxygen species, as well as caspase-3 and -9 activation. Thus these results strongly indicate the necessity of p53 activation and the induction of the apoptotic machinery downstream of mitochondria.

  5. REVIEW: The contribution of medical physics to the development of psoralen photochemotherapy (PUVA) in the UK: a personal reminiscence

    NASA Astrophysics Data System (ADS)

    Diffey, Brian

    2006-07-01

    Psoralen photochemotherapy (PUVA) is the combined treatment of skin disorders with a photosensitizing drug (Psoralen) and UltraViolet A radiation. The introduction of PUVA therapy has arguably been the most important development in dermatology over the past 30 years and from the first days of the treatment being introduced in the UK, British medical physicists were an integral part of the effort to establish it. Medical physicists have contributed to this development in a number of ways, from designing irradiation units in the early days of the technique, through to collaborating with dermatologists in prosecuting clinical and experimental studies aimed at improving patient outcomes. That the dose of UVA radiation is administered quantitatively, and not qualitatively, has probably been the single most important contribution made by several medical physicists over this period. However, despite concerns that were expressed almost 30 years ago about the accuracy with which UVA doses are administered to patients, the medical physics community still has some way to go before we can be satisfied that statements about UVA irradiance and dose can be made with confidence.

  6. Alteration of lymphocyte functions by 8-methoxypsoralen and longwave ultraviolet radiation. I. Suppressive effects of PUVA on T-lymphocyte migration in vitro

    SciTech Connect

    Okamoto, H.; Takigawa, M.; Horio, T.

    1985-03-01

    We investigated the influence of 8-methoxypsoralen (8-MOP) plus long-wave ultraviolet radiation (PUVA) on lymphocyte migration in vitro. Nylon wool-purified, mouse splenic T lymphocytes showed locomotive responses to casein, normal mouse serum (NMS), and zymosan-activated mouse serum (ZAS). Migratory responses to casein and NMS, and to ZAS were remarkably suppressed in lymphocytes exposed to 0.5 J/cm2 UVA plus 0.1 micrograms/ml 8-MOP and to 0.8 J/cm2 UVA plus 8-MOP, respectively. The PUVA treatment used in the present study had no effect on random movement and lymphocyte viability. T lymphocytes cultured in the absence of mitogenic agent for 24 h demonstrated a greater increase in their migration activity than noncultured cells, while lymphocytes cultured after 1.0 J/cm2 PUVA pretreatment remained low. These findings suggest that the therapeutic effect of PUVA on inflammatory skin disorders may be due in part to the suppression of lymphocyte migration.

  7. Luminol-dependent photoemission from single neutrophil stimulated by phorbol ester and calcium ionophore--role of degranulation and myeloperoxidase

    SciTech Connect

    Suematsu, M.; Oshio, C.; Miura, S.; Suzuki, M.; Houzawa, S.; Tsuchiya, M.

    1988-08-30

    Luminol-dependent photonic burst from phorbol ester-treated single neutrophil was visually investigated by using an ultrasensitive photonic image intensifier microscope. Neutrophils stimulated by phorbol myristate acetate (0.1 microgram/ml) alone produced a negligible level of photonic activities in the presence of luminol (10 micrograms/ml). The additional application of 0.1 microM Ca2+ ionophore A23187 induced explosive changes of photonic burst corresponding to the distribution of neutrophils, and these photonic activities were gradually spread to extracellular space. Sodium azide, which prevents myeloperoxidase activity, inhibited Ca2+ ionophore-induced photonic burst from phorbol ester-treated neutrophil. These findings suggest a prerequisite role of degranulation and myeloperoxidase release in luminol-dependent photoemission from stimulated neutrophils.

  8. Increased Duodenal Eosinophil Degranulation in Patients with Functional Dyspepsia: A Prospective Study

    PubMed Central

    Du, Lijun; Shen, Jinhua; Kim, John J.; Yu, Yunxian; Ma, Liqin; Dai, Ning

    2016-01-01

    Functional dyspepsia (FD) is a functional gastrointestinal disorder diagnosed by symptom-based criteria. It has been said that duodenal immune activation plays a role in the pathogenesis of FD. The primary aims of the study were to compare the total number of duodenal eosinophil and evaluate the eosinophil degranulation rate, number of duodenal degranulated eosinophil and mast cell between patients with FD and healthy subjects. We enrolled 96 patients with FD and 24 healthy controls at Sir Run Run Shaw Hospital. The total number of eosinophil was comparable in the second portion of duodenum (D2) and duodenal bulb (D1) between patients with FD and healthy controls (all P > 0.05). Significant higher eosinophil degranulation positive rate in D2 (P = 0.003) and a trend towards higher in D1 (P = 0.084) were observed in patients with FD compared with healthy controls. Moreover, the number of duodenal degranulated eosinophil in patients with FD were significantly increased than healthy controls in D1(9.8 ± 6.3 vs 2.9 ± 2.1 per HPF, P = 0.0002) and a trend towards increase in D2 (10.7 ± 7.7 vs 5.3 ± 0.9 per HPF, P = 0.077), respectively. However, degranulated mast cells in patients with FD were almost same with healthy controls. Increased eosinophils degranulation in duodenum play an important role in pathogenesis of FD. PMID:27708358

  9. A Combination of Screening and Computational Approaches for the Identification of Novel Compounds That Decrease Mast Cell Degranulation

    PubMed Central

    McShane, Marisa P.; Friedrichson, Tim; Giner, Angelika; Meyenhofer, Felix; Barsacchi, Rico; Bickle, Marc

    2015-01-01

    High-content screening of compound libraries poses various challenges in the early steps in drug discovery such as gaining insights into the mode of action of the selected compounds. Here, we addressed these challenges by integrating two biological screens through bioinformatics and computational analysis. We screened a small-molecule library enriched in amphiphilic compounds in a degranulation assay in rat basophilic leukemia 2H3 (RBL-2H3) cells. The same library was rescreened in a high-content image-based endocytosis assay in HeLa cells. This assay was previously applied to a genome-wide RNAi screen that produced quantitative multiparametric phenotypic profiles for genes that directly or indirectly affect endocytosis. By correlating the endocytic profiles of the compounds with the genome-wide siRNA profiles, we identified candidate pathways that may be inhibited by the compounds. Among these, we focused on the Akt pathway and validated its inhibition in HeLa and RBL-2H3 cells. We further showed that the compounds inhibited the translocation of the Akt-PH domain to the plasma membrane. The approach performed here can be used to integrate chemical and functional genomics screens for investigating the mechanism of action of compounds. PMID:25838434

  10. The Anti-Allergic Rhinitis Effect of Traditional Chinese Medicine of Shenqi by Regulating Mast Cell Degranulation and Th1/Th2 Cytokine Balance.

    PubMed

    Shao, Yang-Yang; Zhou, Yi-Ming; Hu, Min; Li, Jin-Ze; Chen, Cheng-Juan; Wang, Yong-Jiang; Shi, Xiao-Yun; Wang, Wen-Jie; Zhang, Tian-Tai

    2017-03-22

    Shenqi is a traditional Chinese polyherbal medicine has been widely used for the treatment of allergic rhinitis (AR). The aim of this study was to investigate the anti-allergic rhinitis activity of Shenqi and explore its underlying molecular mechanism. Ovalbumin (OVA)-induced allergic rhinitis rat model was used to evaluate the anti-allergic rhinitis effect of Shenqi. The effect of Shenqi on IgE-mediated degranulation was measured using rat basophilic leukemia (RBL-2H3) cells. Primary spleen lymphocytes were isolated to investigate the anti-allergic mechanism of Shenqi by detecting the expression of transcription factors via Western blot and the level of cytokines (IL-4 and IFN-γ) via ELISA. In OVA-induced AR rat models, Shenqi relieved the allergic rhinitis symptoms, inhibited the histopathological changes of nasal mucosa, and reduced the levels of IL-4 and IgE. The results from the in vitro study certified that Shenqi inhibited mast cell degranulation. Furthermore, the results of GATA3, T-bet, p-STAT6, and SOCS1 expression and production of IFN-γ and IL-4 demonstrated that Shenqi balanced the ratio of Th1/Th2 (IFN-γ/IL-4) in OVA-stimulated spleen lymphocytes. In conclusion, these results suggest that Shenqi exhibits an obvious anti-allergic effect by suppressing the mast cell-mediated allergic response and by improving the imbalance of Th1/Th2 ratio in allergic rhinitis.

  11. Disaggregation of HeLa-Cx43- and HeLa-spheroids induced by PUVA and photo-oxidized psoralen (POP)

    NASA Astrophysics Data System (ADS)

    Lysenko, Eugene P.; Pliquett, Fritz; Wunderlich, Siegfried; Potapenko, Alexander Y.

    2003-10-01

    To investigate the effects of PUVA (psoralen + UVA-irradiation) and photooxidized psoralen (POP) on cell-cell junctions, two kinds of multicellular spheroids, which were grown from HeLa cells of epithelioid human cervix carcinoma, were used as a model systems: i) defective in intercellular communication through gap junctions (HeLa-spheroids) and ii) transfected with coding sequences of murine connexin Cx43 with restored gap-junction coupling (HeLa-Cx43-spheroids). It was been found that both PUVA and POP induced disaggregation of HeLa-spheroids as well as HeLa-Cx43-spheroids. It implies that gap-junction plaques are not, apparently, critical targets in psoralen-photosensitized disaggregation. The rate of disaggregation was estimated as inverse time of disaggregation of 50% or 100% spheroids in suspensions (1/t50 or 1/t100, respectively). The rate of PUVA-induced disaggregation was found to increase with the increase of UVA-fluence up to 85 kJ/m2. Photosensitization coefficient was highest at low UVA-fluences (4-6 kJ/m2) and significantly decreased with increase in UVA-fluence. The viability of cells in spheroids was estimated with the use of trypan blue stain. At low UVA-fluences, the process of disaggregation was found to occur without the formation of trypan positive cells in spheroids. Results obtained evidence that PUVA-induced disaggregation of spheroids may occur, at least partially, through the action of POP-products.

  12. Regulation of human eosinophil degranulation and activation by endogenous phospholipase A2.

    PubMed Central

    White, S R; Strek, M E; Kulp, G V; Spaethe, S M; Burch, R A; Neeley, S P; Leff, A R

    1993-01-01

    The unique granular proteins of eosinophils may have a pathogenetic role in asthma and in the defense against parasitic infestations. However, the mechanisms regulating eosinophil degranulation are largely unknown. We examined the hypothesis that release of these proteins is regulated by endogenous activation of phospholipase A2. Human eosinophils (HE) were isolated from the peripheral blood of 42 subjects either by Percoll density separation or by negative-selection immunomagnetic fractionation. Eosinophil activation was initiated in vitro with 10(-6) M FMLP and 5 micrograms/ml cytochalasin B and was assessed by measurement of eosinophil peroxidase (EPO), leukotriene C4 (LTC4) and superoxide radical (.O2-) secretion. Treatment of HE with 100 microM mepacrine before activation blocked EPO release (2.0 +/- 0.2 vs 10.2 +/- 2.1% cell content for activated HE, P < 0.004, n = 9), .O2- generation (2.6 +/- 0.9 vs 44.2 +/- 10.8 nmol/ml per 10(6) HE, P < 0.002, n = 5), and LTC4 secretion (68.2 +/- 32.2 vs 1,125.2 +/- 526.8 pg/ml per 10(6) HE, P < 0.04, n = 8). Pretreatment of HE with 100 microM 4-bromophenacyl bromide before activation similarly blocked EPO release, .O2- generation and LTC4 secretion. Addition of AA to HE after treatment with 100 microM mepacrine and before subsequent activation reversed the inhibition of both EPO (10.4 +/- 2.2% with 1 microM AA vs 2.0 +/- 0.2% for mepacrine, n = 5, P < 0.02) and LTC4 secretion (695.1 +/- 412.9 with 10 microM AA vs 68.2 +/- 32.2 pg/ml per 10(6) HE for mepacrine, n = 8, P < 0.04), but did not reverse inhibition of .O2- generation by mepacrine. We demonstrate that secretion of preformed cytotoxic proteins and .O2- by eosinophils is regulated endogenously by phospholipase A2. PMID:8387540

  13. Inhibitory effects of norlignans isolated from Anemarrhena asphodeloides on degranulation of rat basophilic leukemia- 2H3Cells.

    PubMed

    Bak, Jong Phil; Cho, Young Mi; Kim, Inhye; Park, Dae Won; Kwon, Jung Eun; Jeong, Yong Joon; Kwak, Jong Hwan; Kang, Se Chan

    2016-12-01

    Anemarrhena asphodeloides is known to suppress inflammation and lower various fevers. To determine the active component of A. asphodeloides, ethanol (EtOH) extract of A. asphodeloides rhizomes was fractionized. The compounds isolated from the dichloromethane (CH2Cl2) soluble fraction were identified as 4'-O-methylnyasol (1), nyasol (2), 3″-methoxynyasol (3), 3″-hydroxy-4″-methoxy-4″-dehydroxynyasol (4), 4-hydroxybenzaldehyde (5), and 4-hydroxyacetophenone (6). The four norlignans (1-4) potently inhibited the release of β-hexosaminidase from immunoglobulin E (IgE)/dinitrophenol-conjugated bovine serum albumin (DNP-BSA)-treated rat basophilic leukemia (RBL)-2H3 and A23187 plus phorbol 12-myristate 13-acetate co-treated isolated rat primary mast cells, as markers of degranulation and histamine release. The intraperitoneal treatment with the EtOH extract significantly suppressed the fetal reaction, and serum histamine release induced by compound 48/80 in mice. These results suggest that the four active norlignan compounds and the EtOH extract of A. asphodeloides may have potential to be developed as medicines for the treatment of allergies by inhibiting the activation of mast cells.

  14. Differential survival of Escherichia coli uvrA, uvrB, and uvrC mutants to psoralen plus UV-A (PUVA): Evidence for uncoupled action of nucleotide excision repair to process DNA adducts.

    PubMed

    Lage, Claudia; Gonçalves, Silvia R F; Souza, Luciana L; de Pádula, Marcelo; Leitão, Alvaro C

    2010-01-21

    The nucleotide excision repair mechanism (NER) of Escherichia coli is responsible for the recognition and elimination of more than twenty different DNA lesions. Herein, we evaluated the in vivo role of NER in the repair of DNA adducts generated by psoralens (mono- or bi-functional) and UV-A light (PUVA) in E. coli. Cultures of wild-type E. coli K12 and mutants for uvrA, uvrB, uvrC or uvrAC genes were treated with PUVA and cell survival was determined. In parallel, kinetics of DNA repair was also evaluated by the comparison of DNA sedimentation profiles in all the strains after PUVA treatment. The uvrB mutant was more sensitive to PUVA treatment than all the other uvr mutant strains. Wild-type strain, and uvrA and uvrC mutants were able to repair PUVA-induced lesions, as seen by DNA sedimentation profiles, while the uvrB mutant was unable to repair the lesions. In addition, a quadruple fpg nth xth nfo mutant was unable to nick PUVA-treated DNA when the crude cell-free extract was used to perform plasmid nicking. These data suggest that DNA repair of PUVA-induced lesions may require base excision repair functions, despite proficient UvrABC activity. These results point to a specific role for UvrB protein in the repair of psoralen adducts, which appear to be independent of UvrA or UvrC proteins, as described for the classical UvrABC endonuclease mechanism.

  15. Down-regulatory effect of alpha 1-acid glycoprotein on bovine neutrophil degranulation.

    PubMed

    Miranda-Ribera, Alba; Lecchi, Cristina; Bronzo, Valerio; Scaccabarozzi, Licia; Sartorelli, Paola; Franciosi, Federica; Ceciliani, Fabrizio

    2010-07-01

    In this paper, the possible involvement of the acute phase protein alpha(1)-acid glycoprotein (AGP) in the local immunomodulation of inflammation was investigated. The dose response of bovine neutrophils to AGP as to mobilization of primary and secondary granules was studied. It was found that AGP fulfils a protective role against spontaneous exocytosis of secondary, but not primary, granules. This downregulatory effect is much more evident when degranulation is challenged with Zymosan activated serum (ZAS). AGP activity is dose-dependent, the acute phase concentration being more active than the physiological one. Carbohydrate moiety of AGP was found to be critical, since experimentally desialylated protein does not maintain its exocytosis-modulatory activity. The fact that AGP may modulate the degranulation of neutrophils confirms the hypothesis that AGP is heavily involved in the fine tuning of neutrophil activity in the inflammatory environment.

  16. Imidacloprid inhibits IgE-mediated RBL-2H3 cell degranulation and passive cutaneous anaphylaxis

    PubMed Central

    Shi, Linbo; Zou, Li; Gao, Jinyan; Xu, Huaing; Shi, Xiaoyun

    2016-01-01

    Background Imidacloprid has been commonly used as a pesticide for crop protection and acts as nicotinic acetylcholine receptor agonists. Little information about the relationship between imidacloprid and allergy is available. Objective This study aims to examine the effects of imidacoprid on IgE-mediated mast cell activation. Methods The rat basophilic leukemia cell line RBL-2H3 (RBL-2H3 cells) were treated with 10-3 – 10-12 mol/L imidacloprid, followed by measuring the mediator production, influx of Ca2+ in IgE-activated RBL-2H3 cells, and the possible effects of imidacoprid on anti-dinitrophenyl IgE-induced passive cutaneous anaphylaxis (PCA). Results It was shown that imidacoprid suppressed the production of histamine, β-hexosaminidase, leukotriene C4, interleukin-6, tumor necrosis factor-α, and Ca2+ mobilization in IgE-activated RBL-2H3 cells and decreased vascular extravasation in IgE-induced PCA. Conclusion It is the first time to show that imidacloprid suppressed the activation of RBL-2H3 cells. PMID:27803884

  17. Impaired mast cell maturation and degranulation and attenuated allergic responses in Ndrg1-deficient mice.

    PubMed

    Taketomi, Yoshitaka; Sunaga, Kohei; Tanaka, Satoshi; Nakamura, Masanori; Arata, Satoru; Okuda, Tomohiko; Moon, Tae-Chul; Chang, Hyeun-Wook; Sugimoto, Yukihiko; Kokame, Koichi; Miyata, Toshiyuki; Murakami, Makoto; Kudo, Ichiro

    2007-06-01

    We have previously reported that N-myc downstream regulated gene-1 (NDRG1) is an early inducible protein during the maturation of mouse bone marrow-derived mast cells (BMMCs) toward a connective tissue mast cell-like phenotype. To clarify the function of NDRG1 in mast cells and allergic responses, we herein analyzed mast cell-associated phenotypes of mice lacking the Ndrg1 gene. Allergic responses including IgE-mediated passive systemic and cutaneous anaphylactic reactions were markedly attenuated in Ndrg1-deficient mice as compared with those in wild-type mice. In Ndrg1-deficient mice, dermal and peritoneal mast cells were decreased in number and morphologically abnormal with impaired degranulating ability. Ex vivo, Ndrg1-deficient BMMCs cocultured with Swiss 3T3 fibroblasts in the presence of stem cell factor, a condition that facilitates the maturation of BMMCs toward a CTMC-like phenotype, displayed less exocytosis than replicate wild-type cells after the cross-linking of FcepsilonRI or stimulation with compound 48/80, even though the exocytotic response of IL-3-maintained, immature BMMCs from both genotypes was comparable. Unlike degranulation, the production of leukotriene and cytokines by cocultured BMMCs was unaffected by NDRG1 deficiency. Taken together, the altered phenotypes of Ndrg1-deficient mast cells both in vivo and ex vivo suggest that NDRG1 has roles in the terminal maturation and effector function (degranulation) of mast cells.

  18. P2X7 receptors induce degranulation in human mast cells.

    PubMed

    Wareham, Kathryn J; Seward, Elizabeth P

    2016-06-01

    Mast cells play important roles in host defence against pathogens, as well as being a key effector cell in diseases with an allergic basis such as asthma and an increasing list of other chronic inflammatory conditions. Mast cells initiate immune responses through the release of newly synthesised eicosanoids and the secretion of pre-formed mediators such as histamine which they store in specialised granules. Calcium plays a key role in regulating both the synthesis and secretion of mast-cell-derived mediators, with influx across the membrane, in particular, being necessary for degranulation. This raises the possibility that calcium influx through P2X receptors may lead to antigen-independent secretion of histamine and other granule-derived mediators from human mast cells. Here we show that activation of P2X7 receptors with both ATP and BzATP induces robust calcium rises in human mast cells and triggers their degranulation; both effects are blocked by the P2X7 antagonist AZ11645373, or the removal of calcium from the extracellular medium. Activation of P2X1 receptors with αβmeATP also induces calcium influx in human mast cells, which is significantly reduced by both PPADS and NF 449. P2X1 receptor activation, however, does not trigger degranulation. The results indicate that P2X7 receptors may play a significant role in contributing to the unwanted activation of mast cells in chronic inflammatory conditions where extracellular ATP levels are elevated.

  19. A3R Phage and Staphylococcus aureus Lysate Do Not Induce Neutrophil Degranulation

    PubMed Central

    Borysowski, Jan; Międzybrodzki, Ryszard; Wierzbicki, Piotr; Kłosowska, Danuta; Korczak-Kowalska, Grażyna; Weber-Dąbrowska, Beata; Górski, Andrzej

    2017-01-01

    The objective of this study was to evaluate the effects of A3R phage and Staphylococcus aureus lysate obtained after phage infection on neutrophil degranulation. The exocytosis of primary and secondary granules from neutrophils was investigated in vitro in whole blood specimens by flow cytometry based on the expression of specific markers of exocytosis (CD63 for primary granules and CD66b for secondary granules). We found that both A3R and S. aureus lysate had no significant effect on the exocytosis of primary and secondary granules. These data suggest that neither A3R virions nor any products of phage-induced lysis of S. aureus are likely to induce neutrophil degranulation in patients who are treated with phage preparations. Since neutrophil granules contain some potentially toxic proteins, our results provide an important argument for the safety of phage therapy. Moreover, these data indicate that the induction of neutrophil degranulation is not likely to contribute to antibacterial effects of phages. PMID:28230780

  20. Diclofenac induces basophil degranulation without increasing CD63 expression in sensitive patients

    PubMed Central

    Malbrán, A; Yeyati, E; Rey, G L; Galassi, N

    2007-01-01

    Diclofenac (Dc) induces an IgE-independent basophil (Ba) degranulation in susceptible individuals. CD63 Ba expression is utilized as an in vitro test for diagnosis of drug hypersensitivity. We tested the ability of Dc to induce CD63 Ba expression by flow cytometry (BAT) and Ba degranulation using light microscopy (HBDT) in patients sensitive to Dc. We studied 14 patients with diclofenac hypersensitivity, also two patients sensitive to Dermatophagoides pteronyssinus (Dp), and 12 normal controls. HBDT was performed by mononuclear cells toluidine blue staining. BAT determined CD63 expression in antiCD63/anti-IgE/anti-CD45-labelled whole blood. In each case, the percentage of activated Ba post-stimulation with 1 and 10 µg/ml Dc was determined. Positive controls included N-formyl-methionyl-leucyl-phenylalanine (fMLP) peptide-induced activation. IgE-mediated Ba activation was induced with a Dp allergenic extract. With Dc 1 µg/ml, mean HBDT in Dc-susceptible individuals was 33·62 ± 18·35% and 8·49 ± 4·79% in controls (P = 0·0001). Mean BAT was 2·04 ± 1·68% and 1·93 ± 1·40% in controls (P = 0·8). Ba preincubation with Dc did not affect fMLP-induced CD63 expression, neither in Dc-sensitive individuals (P = 0·8) (n = 4) nor in subjects without Dc hypersensitivity (P = 0·25) (n = 4). Ba from the two patients sensitive both to Dc and Dp responded to Dp but not to Dc by BAT: Dc, 1·99 ± 0·78%; Dp: 60·87 ± 9·28%; but showed degranulation by HBDT: Dc, 30·53 ± 1·02%, Dp: 48·78 ± 22·17%. Dc induces Ba degranulation in sensitive patients in a way that does not induce CD63 expression and is different from IgE-mediated and fMLP-mediated degranulation. Our results suggest that CD63 expression is not a reliable diagnostic method for diclofenac allergy. PMID:17177968

  1. Mast cell phenotype, TNFα expression and degranulation status in non-small cell lung cancer

    PubMed Central

    Shikotra, A.; Ohri, C. M.; Green, R. H.; Waller, D. A.; Bradding, P.

    2016-01-01

    Mast cell infiltration of tumour islets represents a survival advantage in non-small cell lung cancer (NSCLC). The phenotype and activation status of these mast cells is unknown. We investigated the mast cell phenotype in terms of protease content (tryptase-only [MCT], tryptase + chymase [MCTC]) and tumour necrosis factor-alpha (TNFα) expression, and extent of degranulation, in NSCLC tumour stroma and islets. Surgically resected tumours from 24 patients with extended survival (ES; mean survival 86.5 months) were compared with 25 patients with poor survival (PS; mean survival 8.0 months) by immunohistochemistry. Both MCT and MCTC in tumour islets were higher in ES (20.0 and 5.6 cells/mm2 respectively) compared to PS patients (0.0 cells/mm2) (p < 0.0001). Both phenotypes expressed TNFα in the islets and stroma. In ES 44% of MCT and 37% of MCTC expressed TNFα in the tumour islets. MCT in the ES stroma were more degranulated than in those with PS (median degranulation index = 2.24 versus 1.73 respectively) (p = 0.0022), and ES islet mast cells (2.24 compared to 1.71, p < 0.0001). Since both MCT and MCTC infiltrating tumour islets in ES NSCLC patients express TNFα, the cytotoxic activity of this cytokine may confer improved survival in these patients. Manipulating mast cell microlocalisation and functional responses in NSCLC may offer a novel approach to the treatment of this disease. PMID:27922077

  2. Increased choroidal mast cells and their degranulation in age-related macular degeneration

    PubMed Central

    Bhutto, Imran A; McLeod, D Scott; Jing, Tian; Sunness, Janet S.; Seddon, Johanna M.; Lutty, Gerard A

    2016-01-01

    Background/Aims Inflammation has been implicated in age-related macular degeneration (AMD). This study investigates the association of mast cells (MCs), a resident choroidal inflammatory cell, with pathological changes in AMD. Methods Human donor eyes included aged controls (n=10), clinically diagnosed with early AMD (n=8), geographic atrophy (GA, n=4), and exudative AMD (n=11). The choroids were excised and incubated alkaline phosphatase (APase; blood vessels) and nonspecific esterase activities (MCs). Degranulated (DG) and nondegranulated (NDG) MCs in four areas of posterior choroid (nasal, nonmacular, paramacular, and submacular) were counted in flat mounts (4∼6 fields/area). Choroids were subsequently embedded in JB-4 and sectioned for histological analyses. Results The number of MCs was significantly increased in all choroidal areas in early AMD (p=0.0006) and in paramacular area in exudative AMD (139.44±55.3 cells/mm2; p=0.0091) and GA (199.08±82.0 cells/mm2; p=0.0019) compared to the aged controls. DG MCs was also increased in paramacular (p=0.001) and submacula choroid (p=0.02) in all forms of AMD. Areas with the greatest numbers of DG MC had loss of choriocapillaris (CC). Sections revealed that the MCs were widely distributed in Sattler's and Haller's layer in the choroidal stroma in aged controls, whereas MCs were frequently found in close proximity to CC in GA and exudative AMD and in choroidal neovascularization (CNV). Conclusion Increased MC numbers and degranulation were observed in all AMD choroids. These results suggest that MC degranulation may contribute to the pathogenesis of AMD: death of CC and RPE and CNV formation. The proteolytic enzymes released from MC granules may result in thinning of AMD choroid. PMID:26931413

  3. Study of cell degranulation with simultaneous microscope imaging and capillary electrophoresis

    SciTech Connect

    Su, H.; Yeung, E.S.

    1999-07-01

    The physical release of single granules from individual rat peritoneal mast cells (RPMCs) was monitored by video recording of the degranulating cells by a high-resolution charge-coupled device (CCD) microscope system. The bright granular core disappears from the image as the vesicular content is dissolved on contact with the extra-cellular fluid. After a fixed time delay, the exocytotic product, serotonin, was detected by capillary electrophoresis coupled with laser-induced native fluorescence (LINF-CE). The timing of the two events is mostly correlated, which supports a fast release mechanism of the granular products. {copyright} {ital 1999} {ital Society for Applied Spectroscopy}

  4. Chelation of Free Zn²⁺ Impairs Chemotaxis, Phagocytosis, Oxidative Burst, Degranulation, and Cytokine Production by Neutrophil Granulocytes.

    PubMed

    Hasan, Rafah; Rink, Lothar; Haase, Hajo

    2016-05-01

    Neutrophil granulocytes are the largest leukocyte population in the blood and major players in the innate immune response. Impaired neutrophil function has been reported in in vivo studies with zinc-deficient human subjects and experimental animals. Moreover, in vitro formation of neutrophil extracellular traps has been shown to depend on free intracellular Zn(2+). This study investigates the requirement of Zn(2+) for several other essential neutrophil functions, such as chemotaxis, phagocytosis, cytokine production, and degranulation. To exclude artifacts resulting from indirect effects of zinc deprivation, such as impaired hematopoietic development and influences of other immune cells, direct effects of zinc deprivation were tested in vitro using cells isolated from healthy human donors. Chelation of Zn(2+) by the membrane permeable chelator N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN) reduced granulocyte migration toward N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLF) and IL-8, indicating a role of free intracellular Zn(2+) in chemotaxis. However, a direct action of Zn(2+) as a chemoattractant, as previously reported by others, was not observed. Similar to chemotaxis, phagocytosis, oxidative burst, and granule release were also impaired in TPEN-treated granulocytes. Moreover, Zn(2+) contributes to the regulatory role of neutrophil granulocytes in the inflammatory response by affecting the cytokine production by these cells. TPEN inhibited the lipopolysaccharide-induced secretion of chemotactic IL-8 and also anti-inflammatory IL-1ra. In conclusion, free intracellular Zn(2+) plays essential roles in multiple neutrophil functions, affecting extravasation to the site of the infection, uptake and killing of microorganisms, and inflammation.

  5. Platelet aggregation but not activation and degranulation during the acute post-ischemic reperfusion phase in livers with no underlying disease

    PubMed Central

    van Golen, Rowan F.; Stevens, Katarzyna M.; Colarusso, Pina; Jaeschke, Hartmut; Heger, Michal

    2016-01-01

    Background Platelets and P-selectin (CD62P) play an unequivocal role in the pathology of hepatic ischemia/reperfusion (I/R) injury. Inhibition or knock-out of P-selectin or immunodepletion of platelets results in amelioration of post-ischemic inflammation, reduced hepatocellular damage, and improved survival. However, P-selectin expression on platelets and endothelial cells, which concurs with platelet activation, has never been clearly demonstrated in I/R-subjected livers. Aims To determine whether platelets become activated and degranulate in the acute phase of liver I/R and whether the platelets interact with neutrophils. Methods Hepatic I/R was induced in male C57BL/6J mice (N = 12) using 37.5-min ischemia time. Platelets, endothelial cells, and neutrophils were fluorescently labeled by systemic administration of non-blocking antibodies. Cell kinetics were monitored by intravital spinning disk confocal microscopy during 90 min of reperfusion. Image analysis and quantification was performed with dedicated software. Results Platelets adhered to sinusoids more extensively in post-ischemic livers compared to livers not subjected to I/R and formed aggregates, which occurred directly after ischemia. Platelets and endothelial cells did not express P-selectin in post-ischemic livers. There was no interaction between platelets and neutrophils. Conclusions Platelets aggregate but do not become activated and do not degranulate in post-ischemic livers. There is no platelet-neutrophil interplay during the early reperfusion phase in a moderate model of hepatic I/R injury. The mechanisms underlying the biological effects of platelets and P-selectin in this setting warrant further investigation. Relevance for patients I/R in surgical liver patients may compromise outcome due to post-ischemic oxidative stress and sterile inflammation. Both processes are mediated in part by platelets. Understanding platelet function during I/R is key to developing effective interventions for I

  6. Leptin enhances survival and induces migration, degranulation, and cytokine synthesis of human basophils.

    PubMed

    Suzukawa, Maho; Nagase, Hiroyuki; Ogahara, Ikuko; Han, Kaiyu; Tashimo, Hiroyuki; Shibui, Akiko; Koketsu, Rikiya; Nakae, Susumu; Yamaguchi, Masao; Ohta, Ken

    2011-05-01

    Basophils are the rarest leukocytes in human blood, but they are now recognized as one of the most important immunomodulatory as well as effector cells in allergic inflammation. Leptin, a member of the IL-6 cytokine family, has metabolic effects as an adipokine, and it is also known to participate in the pathogenesis of inflammatory reactions. Because there is an epidemiologic relationship between obesity and allergy, we examined whether basophil functions are modified by leptin. We found that human basophils express leptin receptor (LepR) at both the mRNA and surface protein levels, which were upregulated by IL-33. Leptin exerted strong effects on multiple basophil functions. It induced a strong migratory response in human basophils, similar in potency to that of basophil-active chemokines. Also, leptin enhanced survival of human basophils, although its potency was less than that of IL-3. Additionally, CD63, a basophil activation marker expressed on the cell surface, was upregulated by leptin, an effect that was neutralized by blocking of LepR. Assessments of basophil degranulation and cytokine synthesis found that leptin showed a strong priming effect on human basophil degranulation in response to FcεRI aggregation and induced Th2, but not Th1, cytokine production by the cells. In summary, the present findings indicate that leptin may be a key molecule mediating the effects of adipocytes on inflammatory cells such as basophils by binding to LepR and activating the cellular functions, presumably exacerbating allergic inflammation.

  7. Mast cell degranulation by a hemolytic lipid toxin decreases GBS colonization and infection

    PubMed Central

    Gendrin, Claire; Vornhagen, Jay; Ngo, Lisa; Whidbey, Christopher; Boldenow, Erica; Santana-Ufret, Veronica; Clauson, Morgan; Burnside, Kellie; Galloway, Dionne P.; Waldorf, Kristina Adams; Piliponsky, Adrian M.; Rajagopal, Lakshmi

    2015-01-01

    Ascending infection of microbes from the lower genital tract into the amniotic cavity increases the risk of preterm birth, stillbirth, and newborn infections. Host defenses that are critical for preventing ascending microbial infection are not completely understood. Group B Streptococcus (GBS) are Gram-positive bacteria that frequently colonize the lower genital tract of healthy women but cause severe infections during pregnancy, leading to preterm birth, stillbirth, or early-onset newborn infections. We recently described that the GBS pigment is hemolytic, and increased pigment expression promotes GBS penetration of human placenta. Here, we show that the GBS hemolytic pigment/lipid toxin and hyperpigmented GBS strains induce mast cell degranulation, leading to the release of preformed and proinflammatory mediators. Mast cell–deficient mice exhibit enhanced bacterial burden, decreased neutrophil mobilization, and decreased immune responses during systemic GBS infection. In a vaginal colonization model, hyperpigmented GBS strains showed increased persistence in mast cell–deficient mice compared to mast cell–proficient mice. Consistent with these observations, fewer rectovaginal GBS isolates from women in their third trimester of pregnancy were hyperpigmented/hyperhemolytic. Our work represents the first example of a bacterial hemolytic lipid that induces mast cell degranulation and emphasizes the role of mast cells in limiting genital colonization by hyperpigmented GBS. PMID:26425734

  8. Overhauser-Enhanced MRI of Elastase Activity from In Vitro Human Neutrophil Degranulation

    PubMed Central

    Parzy, Elodie; Bouchaud, Véronique; Massot, Philippe; Voisin, Pierre; Koonjoo, Neha; Moncelet, Damien; Franconi, Jean-Michel; Thiaudière, Eric; Mellet, Philippe

    2013-01-01

    Background Magnetic resonance imaging can reveal exquisite anatomical details. However several diseases would benefit from an imaging technique able to specifically detect biochemical alterations. In this context protease activity imaging is one of the most promising areas of research. Methodology/Principal Findings We designed an elastase substrate by grafting stable nitroxide free radicals on soluble elastin. This substrate generates a high Overhauser magnetic resonance imaging (OMRI) contrast upon digestion by the target proteases through the modulation of its rotational correlation time. The sensitivity is sufficient to generate contrasted images of the degranulation of neutrophils induced by a calcium ionophore from 2×104 cells per milliliter, well under the physiological neutrophils concentrations. Conclusions/Significance These ex-vivo experiments give evidence that OMRI is suitable for imaging elastase activity from neutrophil degranulation. Provided that a fast protease-substrate is used these results open the door to better diagnoses of a number of important pathologies (cystic fibrosis, inflammation, pancreatitis) by OMRI or Electron Paramagnetic Resonance Imaging in vivo. It also provides a long-expected method to monitor anti-protease treatments efficiency and help pharmaceutical research. PMID:23469112

  9. Hydroxycarbamide reduces eosinophil adhesion and degranulation in sickle cell anaemia patients.

    PubMed

    Pallis, Flavia Rubia; Conran, Nicola; Fertrin, Kleber Yotsumoto; Olalla Saad, Sara Terezinha; Costa, Fernando Ferreira; Franco-Penteado, Carla Fernanda

    2014-01-01

    Inflammation, leucocyte and red cell adhesion to the endothelium contribute to the pathogenesis of sickle cell anaemia. Neutrophils appear to be important for vaso-occlusion, however, eosinophils may also participate in this phenomenon. The role of eosinophils in the pathophysiology of sickle cell anaemia (SCA) and the effect of hydroxycarbamide (HC) therapy on the functional properties of these cells are not understood. Patients with SCA and those on HC therapy (SCAHC) were included in the study. SCAHC individuals presented significantly lower absolute numbers of eosinophils than SCA. Furthermore, SCAHC eosinophils demonstrated significantly lower adhesive properties, compared to SCA eosinophils. SCA and SCAHC eosinophils presented greater spontaneous migration when compared with control eosinophils. Baseline eosinophil peroxidase and reactive oxygen species release was higher for SCA individuals than for control individuals, as were plasma levels of eosinophil derived neurotoxin. SCAHC eosinophil degranulation was lower than that of SCA eosinophil degranulation. Eotaxin-1 and RANTES levels were higher in the plasma of SCA and SCAHC individuals, when compared with controls. These data suggest that eosinophils exist in an activated state in SCA and indicate that these cells play a role in the vaso-occlusive process. The exact mechanism by which HC may alter SCA eosinophil properties is not clear.

  10. Carbohydrate beverage ingestion and neutrophil degranulation responses following cycling to fatigue at 75% VO2 max.

    PubMed

    Bishop, N C; Blannin, A K; Walsh, N P; Gleeson, M

    2001-04-01

    Carbohydrate (CHO) beverage ingestion appears to influence neutrophil functional responses to prolonged exercise of a fixed duration. The aim of this randomised study was to examine the effect of CHO (5% w/v) beverage ingestion on lipopolysaccharide (LPS)-stimulated neutrophil degranulation responses in nine recreationally active males who cycled at 75% VO2 max until fatigue. On two separate occasions, subjects ingested either placebo (PLA) or CHO beverages before and at 15 min intervals during the exercise. Subjects exercised for 31% longer on the CHO trial compared with the PLA trial (P < 0.05). At fatigue plasma glucose concentration was significantly lower on the PLA trial compared with the CHO trial (P < 0.05). Plasma cortisol concentrations had increased similarly on both trials at this time. A marked neutrophilia was evident at fatigue and throughout the 4 h recovery period, the magnitude of which was similar on both trials. At fatigue LPS-stimulated elastase release per neutrophil had fallen similarly on both trials compared with pre-exercise values (47% and 50% on the PLA and CHO trials, respectively). In conclusion, our results suggest that CHO beverage ingestion has negligible influence on the hormonal, circulating neutrophil and LPS-stimulated neutrophil degranulation responses when exercise is performed to fatigue.

  11. The use of fractal dimension and lacunarity in the characterization of mast cell degranulation in rainbow trout (Onchorhynchus mykiss).

    PubMed

    Manera, M; Dezfuli, B S; Borreca, C; Giari, L

    2014-11-01

    Fractal analysis is a reliable method for describing, summarizing object complexity and heterogeneity and has been widely used in biology and medicine to deal with scale, size and shape management problems. The aim of present survey was to use fractal analysis as a complexity measure to characterize mast cells (MCs) degranulation in a rainbow trout ex vivo model (isolated organ bath). Compound 48/80, a condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde, was adopted as MCs degranulation agent in trout intestinal strips. Fractal dimension (D), as a measure of complexity, 'roughness' and lacunarity (λ), as a measure of rotational and translational invariance, heterogeneity, in other words, of the texture, were compared in MCs images taken from intestinal strips before and after compound 48/80 addition to evaluate if and how they were affected by degranulation. Such measures were also adopted to evaluate their discrimination efficacy between compound 48/80 degranulated group and not degranulated group and the results were compared with previously reported data obtained with conventional texture analysis (image histogram, run-length matrix, co-occurrence matrix, autoregressive model, wavelet transform) on the same experimental material. Outlines, skeletons and original greyscale images were fractal analysed to evaluate possible significant differences in the measures values according to the analysed feature. In particular, and considering outline and skeleton as analysed features, fractal dimensions from compound 48/80 treated intestinal strips were significantly higher than the corresponding untreated ones (paired t and Wilcoxon test, p < 0.05), whereas corresponding lacunarity values were significantly lower (paired Wilcoxon test, p < 0.05) but only for outline as analysed feature. Outlines roughness increase is consistent with an increased granular mediators interface, favourable for their biological action; while lacunarity (image

  12. Effects of leptin and tumor necrosis factor-alpha on degranulation and superoxide production of polymorphonuclear neutrophils from Holstein cows.

    PubMed

    Ahmed, Mohamed; Kimura, Kazuhiro; Soliman, Mohamed; Yamaji, Daisuke; Okamatsu-Ogura, Yuko; Makondo, Kennedy; Inanami, Osamu; Saito, Masayuki

    2007-02-01

    Leptin, a pleiotropic hormone regulating food intake and energy expenditure, has been shown to directly modulate human polymorphonuclear neutrophil (PMN) functions or indirectly through the action of tumor necrosis factor-alpha (TNF-alpha). Bovine PMN have considerable different characteristics from human PMN. For example, it does not respond to N-formyl-Methionyl-Leucyl-phenylalanine, a well known human PMN activator. In the present study, we tested the effects of leptin and TNF-alpha on superoxide production and degranulation of bovine peripheral PMN, in which both long isoform of leptin receptor (Ob-Rb) and TNF receptor 1 were expressed. Human leptin, human TNF-alpha, phorbol myristate acetate (PMA) and opsonized zymosan particles (OZP) did not stimulate degranulation responses, while zymosan-activated serum (ZAS) did. Neither leptin nor TNF-alpha enhanced the ZAS-induced degranulation responses. TNF-alpha, PMA, OZP and ZAS increased superoxide production in different magnitudes, whereas leptin did not. TNF-alpha, but not leptin, enhanced OZP- and ZAS-induced superoxide production, possibly, in part due to facilitating translocation of p47(phox), a component of NADPH oxidase. These results indicate that, unlike in human PMN, leptin does not have any direct effect on degranulation and superoxide production in bovine PMN, although TNF-alpha influences superoxide production.

  13. Asynchronous reformation of individual kallikrein-related secretory proteinases in rat submandibular glands following degranulation by cyclocytidine.

    PubMed

    Proctor, G B; Shori, D K; Chan, K M; Garrett, J R

    1993-10-01

    Time scales for the reformation of the secretory granules in granular tubules and their constituent proteinases were assessed after inducing a massive degranulation by intraperitoneal injection of cyclocytidine in conscious animals. The minimum working dose of cyclocytidine to produce the maximum degranulation and depletion of proteinase activity, at 3 h after injection, was 75 mg/kg. Histologically, although most granular tubule cells then appeared to be extensively degranulated, isolated individual cells showing little or no degranulation always persisted. Acinar cells also showed some depletion of secretory material. At 15 h after injecting cyclocytidine the formation of new granules had begun in the granular tubule cells, but it was not extensive or uniform in adjacent cells; however, the acinar cells already appeared to be regranulated. The pattern of granule reformation in granular tubule cells progressed gradually, so that 7-10 days after cyclocytidine-induced degranulation the cells were mostly packed with granules and showed similar appearances to those of normal resting control glands. Individual proteinases in extracts of the glands were assayed specifically using fluorogenic oligopeptide amidase substrates, with and without appropriate inhibitors. This revealed a 95% reduction in total proteinase activity 3 h after cyclocytidine (75 mg/kg). In the same extracts, acinar peroxidase was reduced by 28%. Peroxidase levels recovered to control values within 15 h after cyclocytidine but recovery of proteinases progressed more gradually and did not occur uniformly for the different constituent proteinases. Tissue kallikrein (rK1) showed the most rapid recovery and had reached levels approaching normal within 3 days.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Biochemical and functional characterization of glycosaminoglycans released from degranulating rat peritoneal mast cells: Insights into the physiological role of endogenous heparin.

    PubMed

    Lever, Rebecca; Smailbegovic, Amir; Riffo-Vasquez, Yanira; Gray, Elaine; Hogwood, John; Francis, Stephen M; Richardson, Neville V; Page, Clive P; Mulloy, Barbara

    2016-12-01

    The properties of commercially prepared heparin as an anticoagulant and antithrombotic agent in medicine are better understood than is the physiological role of heparin in its native form, where it is uniquely found in the secretory granules of mast cells. In the present study we have isolated and characterised the glycosaminoglycans (GAGs) released from degranulating rat peritoneal mast cells. Analysis of the GAGs by NMR spectroscopy showed the presence of both heparin and the galactosaminoglycan dermatan sulphate; heparinase digestion profiles and measurements of anticoagulant activity were consistent with this finding. The rat peritoneal mast cell GAGs significantly inhibited accumulation of leukocytes in the rat peritoneal cavity in response to IL-1β (p < 0.05, n = 6/group), and inhibited adhesion and diapedesis of leukocytes in the inflamed rat cremasteric microcirculation in response to LPS (p < 0.001, n = 4/group). FTIR spectra of human umbilical vein endothelial cells (HUVECs) were altered by treatment of the cells with heparin degrading enzymes, and restored by the addition of exogenous heparin. In conclusion, we have shown that rat peritoneal mast cells contain a mixture of GAGs that possess anticoagulant and anti-inflammatory properties.

  15. A neutrophil intrinsic impairment affecting Rab27a and degranulation in cystic fibrosis is corrected by CFTR potentiator therapy

    PubMed Central

    Pohl, Kerstin; Hayes, Elaine; Keenan, Joanne; Henry, Michael; Meleady, Paula; Molloy, Kevin; Jundi, Bakr; Bergin, David A.; McCarthy, Cormac; McElvaney, Oliver J.; White, Michelle M.; Clynes, Martin; McElvaney, Noel G.

    2014-01-01

    Studies have endeavored to reconcile whether dysfunction of neutrophils in people with cystic fibrosis (CF) is a result of the genetic defect or is secondary due to infection and inflammation. In this study, we illustrate that disrupted function of the CF transmembrane conductance regulator (CFTR), such as that which occurs in patients with ∆F508 and/or G551D mutations, correlates with impaired degranulation of antimicrobial proteins. We demonstrate that CF blood neutrophils release less secondary and tertiary granule components compared with control cells and that activation of the low-molecular-mass GTP-binding protein Rab27a, involved in the regulation of granule trafficking, is defective. The mechanism leading to impaired degranulation involves altered ion homeostasis caused by defective CFTR function with increased cytosolic levels of chloride and sodium, yet decreased magnesium measured in CF neutrophils. Decreased magnesium concentration in vivo and in vitro resulted in significantly decreased levels of GTP-bound Rab27a. Treatment of G551D patients with the ion channel potentiator ivacaftor resulted in normalized neutrophil cytosolic ion levels and activation of Rab27a, thereby leading to increased degranulation and bacterial killing. Our results confirm that intrinsic alterations of circulating neutrophils from patients with CF are corrected by ivacaftor, thus illustrating additional clinical benefits for CFTR modulator therapy. PMID:24934256

  16. Mechanism of the modulation of murine peritoneal cell function and mast cell degranulation by low doses of malathion.

    PubMed

    Rodgers, K; Ellefson, D

    1992-01-01

    Malathion is a widely used organophosphate pesticide that modulates immune function at noncholinergic doses. Previous studies showed that this alteration in immune function was the result of enhanced macrophage function. In the present study, the effects of low doses of purified malathion (as low as 0.25 mg/kg malathion) administered orally to mice enhanced the respiratory burst of peritoneal cells. Microscopic examination of the peritoneal cells showed that mast cells were degranulated within 4 hr after malathion administration. The amount of beta-hexosaminidase, an enzyme released upon immunologic degranulation of mast cells, in the peritoneal lavage fluid of malathion-treated mice was also significantly elevated with 4 hours after malathion administration. Treatment of RBL-1, a rat basophilic cell line, cells with malathion, parathion or paroxon in vitro also led to the release of beta-hexosaminidase with paraoxon being the most potent. Further examination of the peritoneal cells of malathion-treated mice showed that the percentage of phagocytic peritoneal cells ingesting mast cell granules and the number of granules ingested per cell were elevated. These data suggest that malathion may enhance the respiratory burst of peritoneal cells through degranulation of peritoneal mast cells and the subsequent exposure to peritoneal cells to mast cell mediators.

  17. p21-activated kinase regulates mast cell degranulation via effects on calcium mobilization and cytoskeletal dynamics

    PubMed Central

    Allen, Jayme D.; Jaffer, Zahara M.; Park, Su-Jung; Burgin, Sarah; Hofmann, Clemens; Sells, Mary Ann; Chen, Shi; Derr-Yellin, Ethel; Michels, Elizabeth G.; McDaniel, Andrew; Bessler, Waylan K.; Ingram, David A.; Atkinson, Simon J.; Travers, Jeffrey B.

    2009-01-01

    Mast cells are key participants in allergic diseases via activation of high-affinity IgE receptors (FcϵRI) resulting in release of proinflammatory mediators. The biochemical pathways linking IgE activation to calcium influx and cytoskeletal changes required for intracellular granule release are incompletely understood. We demonstrate, genetically, that Pak1 is required for this process. In a passive cutaneous anaphylaxis experiment, Wsh/Wsh mast cell–deficient mice locally reconstituted with Pak1−/− bone marrow–derived mast cells (BMMCs) experienced strikingly decreased allergen-induced vascular permeability compared with controls. Consistent with the in vivo phenotype, Pak1−/− BMMCs exhibited a reduction in FcϵRI-induced degranulation. Further, Pak1−/− BMMCs demonstrated diminished calcium mobilization and altered depolymerization of cortical filamentous actin (F-actin) in response to FcϵRI stimulation. These data implicate Pak1 as an essential molecular target for modulating acute mast cell responses that contribute to allergic diseases. PMID:19124833

  18. [Basophil degranulation test (BDT) as a parameter of hyposensitization with Hymenoptera venoms].

    PubMed

    Dietschi, R; Wüthrich, B; Marti-Wyss, S; Cuhat, J

    1987-10-31

    In a population of 24 insect sting allergy patients undergoing venom immunotherapy the basophil degranulation test (BDT) in the patient sera ("unwashed" BDT) and with washed leukocytes ("washed" BDT) after incubation with bee and wasp (yellow jacket) venom was performed before and during treatment. Venom specific IgE and IgG antibodies, detected by means of RAST, were also monitored. The "unwashed" BDT usually became negative within 6-9 months of beginning immunotherapy, whereas the IgE-RAST was still clearly positive. This was attributed to the blocking influence of the venom specific IgG antibodies induced by the venom therapy. In fact, at this time the BDT with "washed" blood leukocytes, i.e. after elimination of the serum antibodies, was generally still positive. Only during further immunotherapy did cellular sensitization in the "washed" BDT gradually disappear, whereas the IgE-RAST usually turned out weakly positive. A third of the patients showed simultaneously negative results of "unwashed" and "washed" BDT, independently of venom specific IgE and IgG levels. These findings suggest a specific reactivity change of the blood basophils (cellular desensitization) induced by the immunotherapy. The BDT can be used as an immunological parameter for IgG-monitoring of the course of venom immunotherapy and--in addition to skin tests and IgE-RAST--as a further criterion for deciding to stop venom therapy if it turns negative with the washed cells.

  19. Two modes of lytic granule fusion during degranulation by natural killer cells.

    PubMed

    Liu, Dongfang; Martina, Jose A; Wu, Xufeng S; Hammer, John A; Long, Eric O

    2011-08-01

    Lytic granules in cytotoxic lymphocytes, which include T cells and natural killer (NK) cells, are secretory lysosomes that release their content upon fusion with the plasma membrane (PM), a process known as degranulation. Although vesicle exocytosis has been extensively studied in endocrine and neuronal cells, much less is known about the fusion of lytic granules in cytotoxic lymphocytes. Here, we used total internal reflection fluorescence microscopy to examine lytic granules labeled with fluorescently tagged Fas ligand (FasL) in the NK cell line NKL stimulated with phorbol ester and ionomycin and in primary NK cells activated by physiological receptor-ligand interactions. Two fusion modes were observed: complete fusion, characterized by loss of granule content and rapid diffusion of FasL at the PM; and incomplete fusion, characterized by transient fusion pore opening and retention of FasL at the fusion site. The pH-sensitive green fluorescence protein (pHluorin) fused to the lumenal domain of FasL was used to visualize fusion pore opening with a time resolution of 30 ms. Upon incomplete fusion, pHluorin emission lasted several seconds in the absence of noticeable diffusion. Thus, we conclude that lytic granules in NK cells undergo both complete and incomplete fusion with the PM, and propose that incomplete fusion may promote efficient recycling of lytic granule membrane after the release of cytotoxic effector molecules.

  20. Echinometrin: a novel mast cell degranulating peptide from the coelomic liquid of Echinometra lucunter sea urchin.

    PubMed

    Sciani, Juliana Mozer; Sampaio, Marlos Cortez; Zychar, Bianca Cestari; Gonçalves, Luis Roberto de Camargo; Giorgi, Renata; Nogueira, Thiago de Oliveira; de Melo, Robson Lopes; Teixeira, Catarina de Fátima Pereira; Pimenta, Daniel Carvalho

    2014-03-01

    Echinometra lucunter is an abundant sea urchin found in Brazilian waters. Accidents caused by this animal are common and are characterized by the penetration of the spines in the skin, which raises an inflammatory reaction through mechanical trauma as well as by the presumable action of toxins. Additionally, there have been reports of inflammatory reaction after the consumption of raw sea urchin eggs. In this work, we have isolated a peptide from E. lucunter coelomic fluid that could elicit inflammatory reactions, such as paw edema, leukocyte recruitment and diminishment of the pain threshold. This peptide was termed Echinometrin. Moreover, the peptide administration was able to produce in vivo degranulation of mouse mast cells, in a dose-response manner. The peptide was 'de novo' sequenced by mass spectrometry and its synthetic analog could reproduce all the observed effects. Sequence alignment indicates that this peptide is comprised in vitellogenin, an abundant nutrient protein present in the gametogenic cells of sea urchins, making it possible that echinometrin would be a cryptide with pro-inflammatory effects.

  1. Enhanced innate immune responses in a brood parasitic cowbird species: degranulation and oxidative burst

    USGS Publications Warehouse

    Hahn, D. Caldwell; Summers, Scott G.; Genovese, Kenneth J.; He, Haiqi; Kogut, Michael H.

    2013-01-01

    We examined the relative effectiveness of two innate immune responses in two species of New World blackbirds (Passeriformes, Icteridae) that differ in resistance to West Nile virus (WNV). We measured degranulation and oxidative burst, two fundamental components of phagocytosis, and we predicted that the functional effectiveness of these innate immune responses would correspond to the species' relative resistance to WNV. The brown-headed cowbird (Molothrus ater), an obligate brood parasite, had previously shown greater resistance to infection with WNV, lower viremia and faster recovery when infected, and lower subsequent antibody titers than the red-winged blackbird (Agelaius phoeniceus), a close relative that is not a brood parasite. We found that cowbird leukocytes were significantly more functionally efficient than those of the blackbird leukocytes and 50% more effective at killing the challenge bacteria. These results suggest that further examination of innate immunity in the cowbird may provide insight into adaptations that underlie its greater resistance to WNV. These results support an eco-immunological interpretation that species like the cowbird, which inhabit ecological niches with heightened exposure to parasites, experience evolutionary selection for more effective immune responses.

  2. Changes in histochemically detectable calcium and zinc during tolbutamide-induced degranulation and subsequent regranulation of rat pancreatic islets.

    PubMed

    Wolters, G H; Pasma, A; Wiegman, J B; Konijnendijk, W

    1983-01-01

    Secretory granules of pancreatic B-cells contain high concentrations of zinc and calcium. The effect of gradual degranulation (induced by tolbutamide over a period of 3 days) and the subsequent regranulation (over a period of 4 days) on the histochemically detectable zinc (Zn) and calcium (Ca) content of B-cells was investigated. Zn was stained by dithizone, Ca by glyoxal-bis-(2-hydroxyanil), (GBHA), and B-granules by aldehyde fuchsin (AF). The staining intensities were determined cytophotometrically. A decrease of the granulation by 50% causes a comparable decrease of the Zn content. Almost complete degranulations, however, hardly further diminished the Zn content. Regranulation restores the Zn content parallel to the granulation. The presence of 40% of the initial Zn content in degranulated B-cells suggests the existence of a non-granular Zn fraction. The Zn content of B-cells may be partly involved in the storage of insulin as a Zn-insulin complex in the secretory vesicles. A-cells, however, contain even more (+ 30%) Zn than B-cells. Degranulation of B-cells is accompanied by a moderate decrease of the zinc content of the A-cells. The function of Zn in A-cells is completely unknown. Degranulation of B-cells causes the GBHA-Ca content to decrease to a very low level parallel to the AF-positive granulation. During regranulation the GBHA-Ca content restores parallel to the granulation and reaches after complete regranulation a slightly higher level than in untreated control rats. Almost complete disappearance of CBHA-Ca in the B-cells is accompanied by a decrease of the total islet calcium content of 33%. The results indicate that GBHA stains a Ca fraction which is mainly localized to the secretory granules. The stainability of granular Ca by GBHA is probably based on: a) the high Ca concentration in the granules, b) the presence of ionized Ca in the granules, due to the low intragranular pH, and c) on the properties of GBHA, which stains, under conditions used

  3. Effects of malathion metabolites on degranulation of and mediator release by human and rat basophilic cells.

    PubMed

    Xiong, S; Rodgers, K

    1997-06-06

    In the present study, the effects of malathion and malathion derivatives on histamine and beta-hexosaminidase release by RBL-1 cells, rat peritoneal mast cells (RPMC), and human peripheral blood basophils (HPBB) and cutaneous mast calls were examined. One hour of incubation of RBL-1 cells with all organophosphate compounds tested, except for malathion and malathion monoacid, led to an increase in histamine release. beta-Hexosaminidase, an enzyme released by basophilic cells and a biochemical marker of degranulation, was not released from RBL-1 cells after 1 h of exposure to organophosphate compounds. Within 4 h, all compounds tested increased the release of histamine and beta-hexosaminidase. Longer exposures led to a decrease in the concentration of the compound that was required to cause mediator release. Exposure of RPMC to organophosphate compounds, with the exception of malathion monoacid and malathion (30 min) or malathion monoacid (1 h), led to the release of histamine, but not beta-hexosaminidase. Incubation of HPBB with malaoxon (51.4 +/- 2.8% total histamine released), malathion diacid (25.7 +/- 2.9%), beta-malathion monoacid (31.4 +/- 2.8%), and isomalathion (57.1 +/- 17.1%) for 1 h led to the release of histamine. Only malaoxon and isomalathion caused beta-hexosaminidase release from HPBB after a 1-h incubation. Incubation of cutaneous mast cells with malaoxon and beta-monoacid for 4 h led to increased release of histamine and beta-hexosaminidase at levels comparable to compound 48/80. These data suggest that malathion metabolites can cause rapid release of histamine from basophilic cells from a variety of origins and species. With prolonged incubation, malathion itself caused the release of mast-cell mediators, suggesting that the cells may be capable of metabolizing malathion. These data also indicate a disparity between the release kinetics of two different mast-cell mediators contained in granules by organophosphates, and that there are different

  4. Silver Nanoparticle-Directed Mast Cell Degranulation Is Mediated through Calcium and PI3K Signaling Independent of the High Affinity IgE Receptor

    PubMed Central

    Alsaleh, Nasser B.; Persaud, Indushekhar; Brown, Jared M.

    2016-01-01

    Engineered nanomaterial (ENM)-mediated toxicity often involves triggering immune responses. Mast cells can regulate both innate and adaptive immune responses and are key effectors in allergic diseases and inflammation. Silver nanoparticles (AgNPs) are one of the most prevalent nanomaterials used in consumer products due to their antimicrobial properties. We have previously shown that AgNPs induce mast cell degranulation that was dependent on nanoparticle physicochemical properties. Furthermore, we identified a role for scavenger receptor B1 (SR-B1) in AgNP-mediated mast cell degranulation. However, it is completely unknown how SR-B1 mediates mast cell degranulation and the intracellular signaling pathways involved. In the current study, we hypothesized that SR-B1 interaction with AgNPs directs mast cell degranulation through activation of signal transduction pathways that culminate in an increase in intracellular calcium signal leading to mast cell degranulation. For these studies, we utilized bone marrow-derived mast cells (BMMC) isolated from C57Bl/6 mice and RBL-2H3 cells (rat basophilic leukemia cell line). Our data support our hypothesis and show that AgNP-directed mast cell degranulation involves activation of PI3K, PLCγ and an increase in intracellular calcium levels. Moreover, we found that influx of extracellular calcium is required for the cells to degranulate in response to AgNP exposure and is mediated at least partially via the CRAC channels. Taken together, our results provide new insights into AgNP-induced mast cell activation that are key for designing novel ENMs that are devoid of immune system activation. PMID:27907088

  5. Mast cell degranulation and de novo histamine formation contribute to sustained post-exercise vasodilation in humans.

    PubMed

    Romero, Steven A; McCord, Jennifer L; Ely, Matthew R; Sieck, Dylan C; Buck, Tahisha M; Luttrell, Meredith J; MacLean, David A; Halliwill, John R

    2016-08-25

    In humans, acute aerobic exercise elicits a sustained post-exercise vasodilation within previously active skeletal muscle. This response is dependent on activation of histamine H1 and H2 receptors, but the source of intramuscular histamine remains unclear. We tested the hypothesis that interstitial histamine in skeletal muscle would be increased with exercise and would be dependent on de novo formation via the inducible enzyme histidine decarboxylase and/or mast cell degranulation. Subjects performed 1 h of unilateral dynamic knee-extension exercise or sham (seated rest). We measured the interstitial histamine concentration and local blood flow (ethanol washout) via skeletal muscle microdialysis of the vastus lateralis In some probes, we infused either α-fluoromethylhistidine hydrochloride (α-FMH), a potent inhibitor of histidine decarboxylase, or histamine H1/H2 receptor blockers. We also measured interstitial tryptase concentrations, a biomarker of mast cell degranulation. Compared with pre-exercise, histamine was increased after exercise by Δ4.2 ± 1.8 ng ml(-1) (P < 0.05), but not when α-FMH was administered (Δ-0.3 ± 1.3 ng ml(-1), P = 0.9). Likewise, local blood flow after exercise was reduced to pre-exercise levels by both α-FMH and H1/H2 blockade. In addition, tryptase was elevated during exercise by Δ6.8 ± 1.1 ng ml(-1) (P < 0.05). Taken together, these data suggest that interstitial histamine in skeletal muscle increases with exercise and results from both de novo formation and mast cell degranulation. This suggests that exercise produces an anaphylactoid signal which affects recovery, and may influence skeletal muscle blood flow during exercise.

  6. Omega-3 fatty acids modulate Weibel-Palade body degranulation and actin cytoskeleton rearrangement in PMA-stimulated human umbilical vein endothelial cells.

    PubMed

    Bürgin-Maunder, Corinna S; Brooks, Peter R; Russell, Fraser D

    2013-11-08

    Long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFAs) produce cardiovascular benefits by improving endothelial function. Endothelial cells store von Willebrand factor (vWF) in cytoplasmic Weibel-Palade bodies (WPBs). We examined whether LC n-3 PUFAs regulate WPB degranulation using cultured human umbilical vein endothelial cells (HUVECs). HUVECs were incubated with or without 75 or 120 µM docosahexaenoic acid or eicosapentaenoic acid for 5 days at 37 °C. WPB degranulation was stimulated using phorbol 12-myristate 13-acetate (PMA), and this was assessed by immunocytochemical staining for vWF. Actin reorganization was determined using phalloidin-TRITC staining. We found that PMA stimulated WPB degranulation, and that this was significantly reduced by prior incubation of cells with LC n-3 PUFAs. In these cells, WPBs had rounded rather than rod-shaped morphology and localized to the perinuclear region, suggesting interference with cytoskeletal remodeling that is necessary for complete WPB degranulation. In line with this, actin rearrangement was altered in cells containing perinuclear WPBs, where cells exhibited a thickened actin rim in the absence of prominent cytoplasmic stress fibers. These findings indicate that LC n-3 PUFAs provide some protection against WBP degranulation, and may contribute to an improved understanding of the anti-thrombotic effects previously attributed to LC n-3 PUFAs.

  7. Dense-core granules in neuroendocrine cells and neurons release their secretory constituents by piecemeal degranulation (review).

    PubMed

    Crivellato, Enrico; Nico, Beatrice; Bertelli, Eugenio; Nussdorfer, Gastone G; Ribatti, Domenico

    2006-12-01

    The term piecemeal degranulation (PMD) refers to a slow releasing process mediated by vesicular transport of stored secretory granule contents. This form of cell secretion was first proposed for basophils, mast cells and eosinophils, but evidence has begun to accumulate that PMD also occurs in dense-core granules of neuroendocrine cells and neurons. This review summarizes the electron-microscopic evidence that has been gathered in support of this view and also discusses the possible physiological significance of PMD in this class of secretory organelles in comparison with 'full fusion' and 'kiss-and-run' exocytosis.

  8. Development of an LC-ESI-MS/MS method for the determination of histamine: application to the quantitative measurement of histamine degranulation by KU812 cells.

    PubMed

    Koyama, Junko; Takeuchi, Atsuko; Tode, Chisato; Shimizu, Maki; Morita, Izumi; Nobukawa, Machiko; Nobukawa, Makiko; Kobayashi, Norihiro

    2009-01-15

    A rapid, simple, and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed for the identification and quantification of histamine without a previous derivatization step or the addition of general ion-pairing reagents to the mobile phase. This method was used to measure histamine release following degranulation of KU812 human basophilic cells, using pyrazol as an internal standard. Analyses were performed on an LC system employing a Cosmosil 5C(18) PAQ column and an isocratic elution with methanol-0.005% trifluoroacetic acid (1:1) at a flow rate of 0.2 mL/min. A triple-quadrupole mass spectrometer, equipped with an electrospray ionization interface was employed, operating in the positive ion mode. The retention time of histamine and the internal standard were 4.0 and 5.0 min, respectively. The relative standard deviations (R.S.D.s) of the retention time and peak area were between 0.47% and 2.03%. Micropipette tip solid-phase extraction (SPE) using LooseTip C(18) allowed for not only rapid sample preparation, but also decreased suppression effects, improving peak shape. This method was used to evaluate the anti-allergic effects of compounds contained in Taxus yunnanensis extracts. Four constituents that were isolated from the wood extracts of T. yunnanensis and sodium cromoglicate, which is used as a first line anti-allergic drug, were tested in an in vitro histamine release inhibition assay. Of these compounds, taxiresinol and isotaxiresinol were more inhibitory than sodium cromoglicate.

  9. SNAP23-Dependent Surface Translocation of Leukotriene B4 (LTB4) Receptor 1 Is Essential for NOX2-Mediated Exocytotic Degranulation in Human Mast Cells Induced by Trichomonas vaginalis-Secreted LTB4.

    PubMed

    Min, Arim; Lee, Young Ah; Kim, Kyeong Ah; El-Benna, Jamel; Shin, Myeong Heon

    2017-01-01

    Trichomonas vaginalis is a sexually transmitted parasite that causes vaginitis in women and itself secretes lipid mediator leukotriene B4 (LTB4). Mast cells are important effector cells of tissue inflammation during infection with parasites. Membrane-bridging SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complexes are critical for fusion during exocytosis. Although T. vaginalis-derived secretory products (TvSP) have been shown to induce exocytosis in mast cells, information regarding the signaling mechanisms between mast cell activation and TvSP is limited. In this study, we found that SNAP23-dependent surface trafficking of LTB4 receptor 1 (BLT1) is required for nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2)-mediated exocytotic degranulation of mast cells induced by TvSP. First, stimulation with TvSP induced exocytotic degranulation and reactive oxygen species (ROS) generation in HMC-1 cells. Next, TvSP-induced ROS generation and exocytosis were strongly inhibited by transfection of BLT1 small interfering RNA (siRNA). TvSP induced trafficking of BLT1 from the cytosol to the plasma membrane. We also found that knockdown of SNAP23 abrogated TvSP-induced ROS generation, exocytosis, and surface trafficking of BLT1 in HMC-1 cells. By coimmunoprecipitation, there was a physical interaction between BLT1 and SNAP23 in TvSP-stimulated HMC-1 cells. Taken together, our results suggest that SNAP23-dependent surface trafficking of BLT1 is essential for exocytosis in human mast cells induced by T. vaginalis-secreted LTB4 Our data collectively demonstrate a novel regulatory mechanism for SNAP23-dependent mast cell activation of T. vaginalis-secreted LTB4 involving surface trafficking of BLT1. These results can help to explain how the cross talk mechanism between parasite and host can govern deliberately tissue inflammatory responses.

  10. Degranulation, density, and distribution of mast cells in the rat thalamus: a light and electron microscopic study in basal conditions and after intracerebroventricular administration of nerve growth factor.

    PubMed

    Florenzano, F; Bentivoglio, M

    2000-09-04

    In the adult rat brain mast cells reside selectively in the thalamus. We investigated thalamic mast cells stained by acidic toluidine blue or pinacyanol, and with histamine immunocytochemistry, focusing on their state of activity revealed by degranulation. Mast cells exhibited perivascular prevalence and high quantitative variability, between cases and in different sections, with no asymmetry or topographical selectivity in thalamic nuclei. Pinacyanol, alone or with erythrosine, stained mast cells with higher sensitivity than toluidine blue. However, toluidine blue was highly predictive of pinacyanol staining and provided the best resolution of mast cell cytoplasmic features. Histamine immunocytochemistry labeled 61% of pinacyanol-stained mast cells. Intensely toluidine blue-stained granulated cells, as well as cells exhibiting different degrees of degranulation that paralleled lighter staining, were observed. The response of thalamic mast cells to intracerebroventricular administration of nerve growth factor (NGF) and control cytochrome-c injections was evaluated after 2, 24, and 72 hours. No obvious changes in mast cell number or distribution were found after treatment, but massive degranulation was frequently observed after NGF administration. Significant decrease of staining intensity of mast cells, supporting enhanced degranulation, was documented in NGF-treated animals by quantitative image analysis. Ultrastructural features of mast cell degranulation, with granule coalescence and matrix dissolution, were detected in untreated and NGF-treated cases. The findings point out that mast cells are active in the thalamus in basal conditions and that NGF has the potential to elicit long-lasting degranulation of thalamic mast cells in vivo, exerting a direct effect and/or priming these cells to react to endogenous stimuli.

  11. Curdlan induces selective mast cell degranulation without concomitant release of LTC4, IL-6 or CCL2.

    PubMed

    Barbosa-Lorenzi, Valéria C; Peyda, Simon; Scheynius, Annika; Nilsson, Gunnar; Lunderius-Andersson, Carolina

    2017-04-01

    Mast cells are sentinel cells with a tissue-specific localization in the interface between the host and the external environment. Their quick and selective response upon encountering pathogens is part of the innate host response and typically initiates the following adaptive immune response. Among several pattern recognition receptors (PRRs) involved in the recognition of pathogens by mast cells, the C-type lectin receptor Dectin-1 has been associated with the recognition of fungi. Our previous studies have shown that mast cells are the predominant cell type expressing Dectin-1 in human skin, and they also recognize and respond to Malassezia sympodialis by producing cytokines connected to the innate host response and upregulating the expression of Dectin-1. In the present study, we investigated mast cell responses to Curdlan, a β-glucan that acts as an agonist for the fungi receptor Dectin-1, and found a unique response pattern with induced degranulation, but surprisingly without synthesis of Leukotriene C4, IL-6 or CCL2. Since mast cells are the predominant Dectin-1 expressing cell in the human skin, this study suggests that mast cell degranulation in response to fungi is an important part of the first line of defense against these pathogens.

  12. Restoration of mossy fiber projection in slice co-cultures of dislocated dentate gyrus and degranulated hippocampus.

    PubMed

    Gaiarsa, J L; Heimrich, B

    1995-05-26

    Regional specificity of the mossy fiber projection is a well described feature of hippocampal intrinsic connectivity. Possible mechanisms involved in the formation of this specific projection include attraction molecules localized in the target area or repulsive cues preventing from ingrowth in non-target areas. To test this hypothesis, using organotypic co-cultures of dentate gyrus and irradiated degranulated hippocampal slices, we have disrupted the pathway normally taken by mossy fibers. The dentate gyrus explant was ectopically placed facing the alveus/stratum oriens of the irradiated hippocampal slice forcing the mossy fibers to cross the stratum oriens to reach their target area. Extensive plexuses of labeled mossy fibers were observed in the hilus and adjacent pyramidal cell layer of non-irradiated dentate gyrus explants. A few mossy fibers crossed the border between the co-cultures and reached their specific termination area in the irradiated hippocampus where they formed characteristic multiple synaptic contacts on their target cells. In addition to mossy fibers, numerous thin and varicose non-mossy fibers invade all parts of the co-cultured hippocampus establishing symmetric synapses. From these data we assume that mossy fiber axons emerging from dislocated non-irradiated dentate gyrus explants find their normal termination zone in the co-cultured degranulated hippocampal slice even if they are forced to run an unusual pathway. These results support the idea that an attraction signal arising from the target area is involved in the formation of this specific projection.

  13. Human Lactobacillus Strains from the Intestine can Suppress IgE-Mediated Degranulation of Rat Basophilic Leukaemia (RBL-2H3) Cells

    PubMed Central

    Harata, Gaku; He, Fang; Takahashi, Kyoko; Hosono, Akira; Miyazawa, Kenji; Yoda, Kazutoyo; Hiramatsu, Masaru; Kaminogawa, Shuichi

    2016-01-01

    Mast cells play a critical role in immunoglobulin E (IgE)-mediated allergic diseases, and the degranulation of mast cells is important in the pathogenesis of these diseases. A disturbance of the intestinal microflora, especially of endogenous lactic acid bacteria, might be a contributing factor for IgE-mediated allergic diseases. Additional knowledge regarding the interaction of human intestinal Lactobacilli with mast cells is still necessary. Twenty-three strains of Lactobacilli, including commercial and reference strains and strains from the human intestine, were tested for their ability to regulate degranulation of cells from rat basophilic leukemia RBL-2H3 cells (RBL-2H3) in vitro based on a β-hexosaminidase release assay. Each of the tested Lactobacilli characteristically suppressed IgE-mediated degranulation of RBL-2H3 cells, and Lactobacillus GG showed the strongest inhibitory effect on the cells. Furthermore, the bacteria isolated from the human intestine significantly suppressed degranulation of RBL-2H3 cellsin comparison with the reference strains. These results suggest that Lactobacilli, particularly those from the human intestine, can affect the activation of mast cells in a strain-dependent manner. Further study should be conducted to analyse the understanding mechanism. PMID:27801804

  14. MiR-221 promotes IgE-mediated activation of mast cells degranulation by PI3K/Akt/PLCγ/Ca(2+) pathway.

    PubMed

    Xu, Hong; Gu, Li-Na; Yang, Qian-Yuan; Zhao, De-Yu; Liu, Feng

    2016-06-01

    Mast cells play a pivotal role in the immediate reaction in asthma. In a previous study, it was found that MicroRNA-221 (miR-221) was associated with asthma. Hence, in the present study, the role and the potential mechanisms of miR-221 on immunoglobulin E (IgE)-mediated activation of mast cells degranulation were investigated. MiR-221 expression was first quantified by qRT-PCR in IgE-mediated activation of mast cells. RBL-2H3 cells were then transfected with miR-221 mimic or miR-221 inhibitor, the IgE-mediated degranulation was detected in mast cells. The influence of miR-221 on expression of phospholipase C gamma (PLCγ1), p-PLCγ1, protein kinase B (Akt), phospho-Akt (p-Akt), inhibitor of kappa B (IκB-α), and phospho-IκB-α (p-IκB-α) were examined by Western blot, whereas free calcium ion (Ca(2+)) level was measured by flow cytometry and NF-κB expression was determined by EMSA. Phosphoinositide 3-kinase (PI3K)-inhibitor (LY294002) and NF-κB-inhibitor [pyrrolidine dithiocarbamate (PDTC)] were used to investigate the role of PI3K/Akt pathway and NF-κB in miR-221 promoting IgE-mediated activation of mast cells degranulation. The expression of miR-221 was upregulated in IgE-mediated activation of mast cells, and it was overexpressed in miR-221 mimic transfected cells. The degranulation was found to be significantly increased in miR-221 overexpressed cells while it was found to be significantly decreased in miR-221 downregulated cells. The expression of p-PLCγ1, p-Akt, p-IκB-α as well as NF-κB and Ca(2+) release were increased in miR-221 overexpressed cells. PI3K-inhibitor (LY294002) could rescue the promotion of degranulation caused by miR-221 in IgE-mediated activation of mast cells. However, NF-κB-inhibitor (PDTC) could not rescue the promotion of degranulation caused by miR-221 in IgE-mediated activation of mast cells. MiR-221 promotes IgE-mediated activation of mast cells degranulation by PI3K/Akt/PLCγ/Ca(2+) signaling pathway, in a non

  15. Resolution of cellular compartments involved in membrane potential changes accompanying IgE-mediated degranulation of rat basophilic leukemia cells.

    PubMed Central

    Sagi-Eisenberg, R; Pecht, I

    1984-01-01

    The overall membrane potential of rat basophilic leukemia cells (RBL-2H3) calculated from the transmembrane distribution of the lipophilic, tritium-labelled cation tetraphenyl-phosphonium [( 3H]TPP+) was resolved into its mitochondrial and plasma membrane potential components. Using the mitochondrial uncoupler carbonylcyanide-p-trifluormethoxyphenyl hydrazone (FCCP) which collapses the mitochondrial potential, it was shown that about one third of the overall potential resulted from the mitochondrial contribution. Degranulation of the RBL cells induced by two different IgE-cross-linking agents (specific antigen and anti-IgE antibodies), was accompanied by, and well correlated with, a decrease in the overall potential. However, evaluation of the source of these observed potential changes revealed that the FCCP-insensitive fraction of the overall potential, delta psi P, (representing the plasma membrane potential), was not affected. In contrast, the FCCP-sensitive component due to the mitochondrial potential decreased when receptor cross-linking increased. Thus, the observed decrease in the overall potential is most probably a secondary event in the sequence leading from stimulus to secretion. Indeed, exposure of the RBL cells either to a high external concentration of K+ ions or to a high amount of external TPP+, both causing depolarization, failed to trigger degranulation. It is suggested that the apparent decrease in the measured overall potential is a reflection of the mitochondrial membrane depolarization. The latter is most probably caused by mitochondrial Ca2+ uptake initiated by the increase in the intracellular concentration of Ca2+ which follows cells activation. PMID:6232134

  16. Novel phenotype in beagle dogs characterized by skin response to compound 48/80 focusing on skin mast cell degranulation.

    PubMed

    Uchida, Mitsuhiro; Ito, Fumi; Tsuchiya, Toshiyuki; Shoji, Yoko; Kurosawa, Toru

    2015-01-01

    Beagle dogs have long been employed in toxicology studies and as skin disease models. Compared with other experimental animal species, they are known to be susceptible to skin responses, such as rashes, from exposure to various chemical compounds. Here, a unique dog phenotype was identified that showed no skin response to compound 48/80, a mast cell degranulating agent. Although the skin responses to intradermal injection of polyoxyethylene castor oil derivative (HCO-60, a nonionic detergent), histamine dihydrochloride, concanavalin A (IgE receptor-mediated stimuli), or calcium ionophore A23187 were comparable in wild-type (WT) dogs and these nonresponder (NR) dogs, only the response to compound 48/80 was entirely absent from NR dogs. The skin mast cell density and histamine content per mast cell were histologically comparable between WT and NR dogs. By checking for skin responses to compound 48/80, NR dogs were found to exist at the proportion of 17-20% among four animal breeders. From retrospective analysis of in-house breeding histories, the NR phenotype appears to conform to the Mendelian pattern of recessive inheritance. The standard skin response in WT dogs developed at 2-4 months of age. In conclusion, this unique phenotype, typified by insensitivity in the compound 48/80-induced degranulation pathway in mast cells, has been widely retained by recessive inheritance in beagle dogs among general experimental animal breeders. The knowledge concerning this phenotype could lead to better utilization of dogs in studies and aid in model development.

  17. A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent

    PubMed Central

    Shim, Juyoung; Gosse, Julie A.

    2013-01-01

    Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a process that results in the exocytosis of allergic mediators. Modulation of mast cell degranulation by drugs and toxicants may have positive or adverse effects on human health. Mast cell function has been dissected in detail with the use of rat basophilic leukemia mast cells (RBL-2H3), a widely accepted model of human mucosal mast cells3-5. Mast cell granule component and the allergic mediator β-hexosaminidase, which is released linearly in tandem with histamine from mast cells6, can easily and reliably be measured through reaction with a fluorogenic substrate, yielding measurable fluorescence intensity in a microplate assay that is amenable to high-throughput studies1. Originally published by Naal et al.1, we have adapted this degranulation assay for the screening of drugs and toxicants and demonstrate its use here. Triclosan is a broad-spectrum antibacterial agent that is present in many consumer products and has been found to be a therapeutic aid in human allergic skin disease7-11, although the mechanism for this effect is unknown. Here we demonstrate an assay for the effect of triclosan on mast cell degranulation. We recently showed that triclosan strongly affects mast cell function2. In an effort to avoid use of an organic solvent, triclosan is dissolved directly into aqueous buffer with heat and stirring, and resultant concentration is confirmed using UV-Vis spectrophotometry (using ε280 = 4,200 L/M/cm)12. This protocol has the potential to be used with a variety of chemicals to determine their effects on mast cell degranulation, and more broadly, their allergic potential. PMID:24300285

  18. Restoration of Ca2+ influx and degranulation capacity of variant RBL-2H3 cells upon implantation of isolated cromolyn binding protein

    PubMed Central

    Mazurek, N.; Bashkin, P.; Loyter, A.; Pecht, I.

    1983-01-01

    Recently, variants of the rat basophilic leukemia cells (RBL-2H3), deficient in their binding capacity for the antiallergic drug cromolyn but displaying unimpaired ability to bind IgE, were selected and cloned [Mazurek, N., Bashkin, P., Petrank, A. & Pecht, I. (1983) Nature (London) 303, 528-530]. Although the histamine content and the number of IgE receptors in these variants are similar to those of the parental cells, they cannot be stimulated immunologically to allow Ca2+ influx and to degranulate. In contrast, the Ca2+ ionophore A23187 causes these variants to degranulate, indicating that the mechanism distal to the Ca2+ gating is intact in the variants. The cromolyn binding protein (CBP), present in the membranes of RBL-2H3 cells, has recently been isolated by affinity chromatography under nondenaturing conditions. In the current study we have used Sendaivirus envelopes as fusogenic carriers to implant the purified CBP into the membrane of variant basophils that were defective in it. This fusion leads to the restoration of Ca2+ uptake and degranulation capacity of the variants after IgE-mediated stimulation. These restored activities seem to show a sigmoidal dependence on the amount of incorporated CBP. Saturation values comparable to those of the parental line are reached when the level of implanted CBP approaches its density on the latter line. The restored capacity is due to the implanted CBP, because the reinstated immunological response can be blocked by the inhibitory drug cromolyn and by monoclonal antibodies specific to CBP, both shown to prevent Ca2+ uptake and degranulation in mast cells and parental RBL-2H3 cells. These results point out that CBP plays an important role in the Ca2+ gating process resulting in degranulation. Images PMID:6577465

  19. Molecular hydrogen suppresses FcepsilonRI-mediated signal transduction and prevents degranulation of mast cells.

    PubMed

    Itoh, Tomohiro; Fujita, Yasunori; Ito, Mikako; Masuda, Akio; Ohno, Kinji; Ichihara, Masatoshi; Kojima, Toshio; Nozawa, Yoshinori; Ito, Masafumi

    2009-11-27

    Molecular hydrogen ameliorates oxidative stress-associated diseases in animal models. We found that oral intake of hydrogen-rich water abolishes an immediate-type allergic reaction in mice. Using rat RBL-2H3 mast cells, we demonstrated that hydrogen attenuates phosphorylation of the FcepsilonRI-associated Lyn and its downstream signal transduction, which subsequently inhibits the NADPH oxidase activity and reduces the generation of hydrogen peroxide. We also found that inhibition of NADPH oxidase attenuates phosphorylation of Lyn in mast cells, indicating the presence of a feed-forward loop that potentiates the allergic responses. Hydrogen accordingly inhibits all tested signaling molecule(s) in the loop. Hydrogen effects have been solely ascribed to exclusive removal of hydroxyl radical. In the immediate-type allergic reaction, hydrogen exerts its beneficial effect not by its radical scavenging activity but by modulating a specific signaling pathway. Effects of hydrogen in other diseases are possibly mediated by modulation of yet unidentified signaling pathways. Our studies also suggest that hydrogen is a gaseous signaling molecule like nitric oxide.

  20. Can Puva Darken Grey Hair.

    PubMed

    Pasricha, J S

    1987-01-01

    Grey hairs obtained from patients having premature grey hairs were exposed to UVA or UVB for 30 mmutes daily for 17 days and another group of grey hairs were first daily painted with 1% aqueous solution of psoralen and then exposed to UVA for 30 minutes for 17 days. Under neither of these conditions, the greys hairs showed any darkening.

  1. Setaria cervi dual specific phosphatase: characterization and its effect on eosinophil degranulation.

    PubMed

    Rathaur, S; Rai, R; Srikanth, E; Srivastava, S

    2009-07-01

    Setaria cervi, a bovine filarial parasite contains significant acid phosphatase (AcP) activity in its various life stages. Two forms of AcP were separated from somatic extract of adult female parasite using cation exchange, gel filtration and concavalin affinity chromatography. One form having a molecular mass of 79 kDa was characterized as dual specific protein tyrosine phosphatase (ScDSP) based on substrate specificity and inhibition studies. With various substrates tested, it showed significant activity in the order of phospho-L-tyrosine>pNPP>ADP>phospho-L-serine. Inhibition by orthovanadate, fluoride, molybdate, and zinc ions further confirms protein tyrosine phosphatase nature of the enzyme. Km and Vmax determined with various substrates were found to be 16.66 mM, 25.0 microM/ml/min with pNPP; 20.0 mM, 40.0 microM/ml/min with phospho-L-tyrosine and 27.0 mM, 25.0 microM/ml/min with phospho-L-serine. KI with pNPP and sodium orthovanadate (IC50 33.0 microM) was calculated to be 50.0 mM. Inhibition with pHMB, silver nitrate, DEPC and EDAC suggested the presence of cysteine, histidine and carboxylate residues at its active site. Cross-reactivity with W. bancrofti-infected sera was demonstrated by Western blotting. ScDSP showed elevated levels of IgE in chronic filarial sera using ELISA. Under in vitro conditions, ScDSP resulted in increased effector function of human eosinophils when stimulated by IgG, which showed a further decrease with increasing enzyme concentration. Results presented here suggest that S. cervi DSP should be further studied to determine its role in pathogenesis and the persistence of filarial parasite.

  2. Mast cell desensitization inhibits calcium flux and aberrantly remodels actin

    PubMed Central

    Ang, W.X. Gladys; Church, Alison M.; Kulis, Mike; Choi, Hae Woong; Burks, A. Wesley

    2016-01-01

    Rush desensitization (DS) is a widely used and effective clinical strategy for the rapid inhibition of IgE-mediated anaphylactic responses. However, the cellular targets and underlying mechanisms behind this process remain unclear. Recent studies have implicated mast cells (MCs) as the primary target cells for DS. Here, we developed a murine model of passive anaphylaxis with demonstrated MC involvement and an in vitro assay to evaluate the effect of DS on MCs. In contrast with previous reports, we determined that functional IgE remains on the cell surface of desensitized MCs following DS. Despite notable reductions in MC degranulation following DS, the high-affinity IgE receptor FcεRI was still capable of transducing signals in desensitized MCs. Additionally, we found that displacement of the actin cytoskeleton and its continued association with FcεRI impede the capacity of desensitized MCs to evoke the calcium response that is essential for MC degranulation. Together, these findings suggest that reduced degranulation responses in desensitized MCs arise from aberrant actin remodeling, providing insights that may lead to improvement of DS treatments for anaphylactic responses. PMID:27669462

  3. Mast cell-dependent allergic responses are inhibited by ethanolic extract of adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) testa.

    PubMed

    Chen, Hong-Jhang; Shih, Chun-Kuang; Hsu, Hsin-Yi; Chiang, Wenchang

    2010-02-24

    Allergy is an immune dysfunction caused by degranulation from mast cells in the early phase and cytokine secretion in the late phase of the cell. The purpose of this study was to investigate the effects of adlay (Job's tears, Coix lachryma-jobi L. var. ma-yuen Stapf) testa against beta-hexosaminidase release as a marker of degranulation in rat basophilic leukemia (RBL)-2H3 cells. The ethyl acetate fraction from ethanolic extracts of adlay testa (ATE-EtOAc) exhibited potent inhibitory activity that suppressed degranulation from RBL-2H3 cells stimulated by 1 microM A23187. The 20%-80% EtOAc/Hex subfractions of ATE-EtOAc significantly inhibited histamine release with a IC(50) of 75-100 microg/mL. In addition, the ATE-EtOAc subfractions suppressed interleukin (IL)-4, IL-6, and tumor necrosis factor-alpha secretion in RBL-2H3 cells, indicating that adlay testa were able to inhibit cytokine secretion. In order to explore the inhibitory mechanism of adlay testa in mast cell degranulation, we examined the activation of intracellular signaling molecules. Adlay testa inhibited the phosphorylation ERK expression. Furthermore, the two major active compounds, 4-hydroxyacetophenone and p-coumaric acid, were isolated from the ATE-EtOAc subfractions. These results suggest that ATE had an inhibitory effect on allergic response via the ERK signaling transduction in RBL-2H3 cells.

  4. The role of the Annexin-A1/FPR2 system in the regulation of mast cell degranulation provoked by compound 48/80 and in the inhibitory action of nedocromil.

    PubMed

    Sinniah, Ajantha; Yazid, Samia; Perretti, M; Solito, Egle; Flower, R J

    2016-03-01

    1.We investigated the role of Annexin (ANX)-A1 and its receptor, ALX/FPR2, in the regulation of mast cell degranulation produced by compound 48/80. 2.Both human cord-blood derived mast cells (CBDMCs) and murine bone marrow derived mast cells (BMDMCs) release phosphorylated ANX-A1 during treatment with glucocorticoids or the mast cell 'stabilising' drugs ketotifen and nedocromil. 3.Compound 48/80 also stimulated ANX-A1 phosphorylation and release and this was also potentiated by nedocromil. Anti-ANX-A1 neutralising monoclonal antibodies (Mabs) enhanced the release of pro-inflammatory mediators in response to compound 48/80. 4.Nedocromil and ketotifen potently inhibited the release of histamine, PGD2, tryptase and β-hexosaminidase from mast cells challenged with compound 48/80. Anti-ANX-A1 neutralising Mabs prevented the inhibitory effect of these drugs. 5.BMDMCs derived from Anx-A1−/− mice were insensitive to the inhibitory effects of nedocromil or ketotifen but cells retained their sensitivity to the inhibitory action of hu-r-ANX-A1. 6.The fpr2/3 antagonist WRW4 blocked the action of nedocromil on PGD2, but not histamine, release. BMDMCs derived from fpr2/3−/− mice were insensitive to the inhibitory effects of nedocromil on PGD2, but not histamine release. 7.Compound 48/80 stimulated both p38 and JNK phosphorylation in CBDMCs and this was inhibited by nedocromil. Inhibition of p38 phosphorylation was ANX-A1 dependent. 8.We conclude that ANX-A1 is an important regulator of mast cell reactivity to compound 48/80 exerting a negative feedback effect through a mechanism that depends at least partly on the FPR receptor.

  5. Accumulation of Major Histocompatibility Complex Class II Molecules in Mast Cell Secretory Granules and Their Release upon Degranulation

    PubMed Central

    Raposo, Graça; Tenza, Danielle; Mecheri, Salahedine; Peronet, Roger; Bonnerot, Christian; Desaymard, Catherine

    1997-01-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60–80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles. PMID:9398681

  6. Accumulation of major histocompatibility complex class II molecules in mast cell secretory granules and their release upon degranulation.

    PubMed

    Raposo, G; Tenza, D; Mecheri, S; Peronet, R; Bonnerot, C; Desaymard, C

    1997-12-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60-80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles.

  7. Transient fusion ensures granule replenishment to enable repeated release after IgE-mediated mast cell degranulation.

    PubMed

    Balseiro-Gomez, Santiago; Flores, Juan A; Acosta, Jorge; Ramirez-Ponce, M Pilar; Ales, Eva

    2016-11-01

    To ensure normal immune function, mast cells employ different pathways to release mediators. Here, we report a thus far unknown capacity of mast cells to recycle and reuse secretory granules after an antigen-evoked degranulation process under physiological conditions; this phenomenon involves the existence of a recycling secretory granule pool that is available for release in a short time scale. Rapid endocytic modes contributed to the recycling of ∼60% of the total secretory granule population, which involved kiss-and-run and cavicapture mechanisms, causing retention of the intragranular matrix. We found the presence of normal-size granules and giant actomyosin- and dynamin-dependent granules, which were characterized by large quantal content. These large structures allowed the recovered mast cells to release a large amount of 5-HT, compensating for the decrease in the number of exocytosed secretory granules. This work uncovers a new physiological role of the exo-endocytosis cycle in the immunological plasticity of mast cells and reveals a new property of their biological secretion.

  8. Polydatin (PD) inhibits IgE-mediated passive cutaneous anaphylaxis in mice by stabilizing mast cells through modulating Ca{sup 2+} mobilization

    SciTech Connect

    Yuan, Meichun; Li, Jianjie; Lv, Jingzhang; Mo, Xucheng; Yang, Chengbin; Chen, Xiangdong; Liu, Zhigang; Liu, Jie

    2012-11-01

    Mast cells play a key role in the pathogenesis of asthma and are a promising target for therapeutic intervention in asthma. This study investigated the effects of polydatin (PD), a resveratrol glucoside, on mast cell degranulation upon cross-linking of the high-affinity IgE receptors (FcεRI), as well as the anti-allergic activity of PD in vivo. Herein, we demonstrated that PD treatment for 30 min suppressed FcεRI-mediated mast cell degranulation in a dose-dependent manner. Concomitantly, PD significantly decreased FcεRI-mediated Ca{sup 2+} increase in mast cells. The suppressive effects of PD on FcεRI-mediated Ca{sup 2+} increase were largely inhibited by using LaCl{sub 3} to block the Ca{sup 2+} release-activated Ca{sup 2+} channels (CRACs). Furthermore, PD significantly inhibited Ca{sup 2+} entry through CRACs evoked by thapsigargin (TG). Knocking down protein expression of Orai1, the pore-forming subunit of CRACs, significantly decreased PD suppression of FcεRI-induced intracellular Ca{sup 2+} influx and mast cell degranulation. In a mouse model of mast cell-dependent passive cutaneous anaphylaxis (PCA), in vivo PD administration suppressed mast cell degranulation and inhibited anaphylaxis. Taken together, our data indicate that PD stabilizes mast cells by suppressing FcεRI-induced Ca{sup 2+} mobilization mainly through inhibiting Ca{sup 2+} entry via CRACs, thus exerting a protective effect against PCA. -- Highlights: ► Polydatin can prevent the pathogenesis of passive cutaneous anaphylaxis in mice. ► Polydatin stabilizes mast cells by decreasing FcεRI-mediated degranulation. ► Polydatin suppresses Ca{sup 2+} entry through CRAC channels in mast cells.

  9. Preliminary characterization of diacylglycerol generation in human basophils: temporal relationship to histamine release and resolution of degranulation.

    PubMed

    Oriente, A; Hundley, T; Hubbard, W C; MacGlashan, D W

    1997-05-01

    Purified human basophils were examined for changes in diacylglycerol levels to determine whether the transient nature of a N-formyl-methionyl-leucyl-phenylalanine (fMLP) -stimulated elevation in membrane protein kinase C (PKC) activity could be explained by the transient production of diacylglycerol (DAG). In preliminary experiments total DAG levels were measured by the DAG kinase assay. Although elevations followed stimulation with 1 microM fMLP (basal levels of 15 pmol/10(6) basophils vs. 45 pmol/10(6) basophils at the 3-min time point), there were no detectable changes in the first 60 s of the reaction. Histamine release is typically complete by 30-45 s. Measurement of inositol trisphosphate indicated a rapid increase by 5 s of 2.5 pmol/10(6) basophils. If DAG were produced at similar levels, the DAG kinase assay would not have detected the elevation. Consequently, fMLP-stimulated basophils were examined for changes in 1-stearoyl, 2-arachidonoyl, 3-sn-glycerol (SA-DAG) and 1-oleoyl, 2-arachidonoyl, 3-sn-glycerol by GC-NICIMS (negative ion chemical ionization mass spectroscopy). A 5-s elevation in these two species averaged 2 pmol/10(6) basophils, consistent with the inositol trisphosphate levels and occurring during the period of histamine release. However, a much more pronounced second phase to the SA-DAG response also occurred, mirroring the total DAG levels. This second phase of the DAG response, either total or SA-DAG, was transient on a time scale temporally coincident with the appearance and resolution of degranulation sacs as measured by fluorescence microscopy. These data suggest that there is selective generation of DAG species in the early reaction and the later appearance of DAG may be related to the formation and resolution of granule structures that follow the secretion of histamine.

  10. Immune Response to Snake Envenoming and Treatment with Antivenom; Complement Activation, Cytokine Production and Mast Cell Degranulation

    PubMed Central

    Stone, Shelley F.; Isbister, Geoffrey K.; Shahmy, Seyed; Mohamed, Fahim; Abeysinghe, Chandana; Karunathilake, Harendra; Ariaratnam, Ariaranee; Jacoby-Alner, Tamara E.; Cotterell, Claire L.; Brown, Simon G. A.

    2013-01-01

    cell degranulation but not further complement activation. Anaphylaxis is probably triggered by non allergen-specific activation of mast cells and may be related to the quality of available antivenom preparations, as well as a priming effect from the immune response to the venom itself. PMID:23936562

  11. Thrombomodulin inhibits the activation of eosinophils and mast cells.

    PubMed

    Roeen, Ziaurahman; Toda, Masaaki; D'Alessandro-Gabazza, Corina N; Onishi, Masahiro; Kobayashi, Tetsu; Yasuma, Taro; Urawa, Masahito; Taguchi, Osamu; Gabazza, Esteban C

    2015-01-01

    Eosinophils and mast cells play critical roles in the pathogenesis of bronchial asthma. Activation of both cells leads to the release of pro-inflammatory mediators in the airway of asthmatic patients. Recently, we have shown that inhaled thrombomodulin inhibits allergic bronchial asthma in a mouse model. In the present study, we hypothesize that thrombomodulin can inhibit the activation of eosinophils and mast cells. The effect of thrombomodulin on the activation and release of inflammatory mediators from eosinophils and mast cells was evaluated. Thrombomodulin inhibited the eotaxin-induced chemotaxis, upregulation of CD11b and degranulation of eosinophils. Treatment with thrombomodulin also significantly suppressed the degranulation and synthesis of inflammatory cytokines and chemokines in eosinophils and mast cells. Mice treated with a low-dose of inhaled thrombomodulin have decreased number of eosinophils and activated mast cells and Th2 cytokines in the lungs compared to untreated mice. The results of this study suggest that thrombomodulin may modulate allergic responses by inhibiting the activation of both eosinophils and mast cells.

  12. Degranulation of mast cells located in median eminence in response to compound 48/80 evokes adrenocortical secretion via histamine and CRF in dogs.

    PubMed

    Matsumoto, Itsuro; Inoue, Yasuhisa; Tsuchiya, Katsuhiko; Shimada, Toshio; Aikawa, Tadaomi

    2004-10-01

    The effect of intracerebroventricular infusion of compound 48/80 (C48/80), a mast cell secretagogue, on adrenal cortisol secretion was investigated in dogs under pentobarbital sodium anesthesia. A marked increase in adrenal cortisol secretion was elicited by C48/80 along with a concomitant increase in the plasma levels of cortisol and immunoreactive ACTH, but neither arterial blood pressure and heart rate nor the plasma histamine level altered significantly. Pretreatment with either anti-CRF antiserum or pyrilamine maleate (H(1) histamine-receptor antagonist) significantly attenuated the C48/80-evoked increase in cortisol secretion, but pretreatment with metiamide (H(2)-receptor antagonist) significantly potentiated it. Significant attenuation of the C48/80-evoked increase in cortisol also occurred in dogs given ketotifen, a mast cell stabilizing drug, before pharmacologic challenge. In the pars tuberalis and median eminence (ME), mast cells were highly concentrated in close association with the primary plexus of the hypophysial portal system. Degranulated mast cells were extensively found in the ME of C48/80-treated animals. These results suggest that mast cells located in these regions liberated histamine within the brain as a result of degranulation induced by C48/80 and that this led to activation of the hypothalamic-pituitary-adrenocortical axis.

  13. Tyrosol Suppresses Allergic Inflammation by Inhibiting the Activation of Phosphoinositide 3-Kinase in Mast Cells.

    PubMed

    Je, In-Gyu; Kim, Duk-Sil; Kim, Sung-Wan; Lee, Soyoung; Lee, Hyun-Shik; Park, Eui Kyun; Khang, Dongwoo; Kim, Sang-Hyun

    2015-01-01

    Allergic diseases such as atopic dermatitis, rhinitis, asthma, and anaphylaxis are attractive research areas. Tyrosol (2-(4-hydroxyphenyl)ethanol) is a polyphenolic compound with diverse biological activities. In this study, we investigated whether tyrosol has anti-allergic inflammatory effects. Ovalbumin-induced active systemic anaphylaxis and immunoglobulin E-mediated passive cutaneous anaphylaxis models were used for the immediate-type allergic responses. Oral administration of tyrosol reduced the allergic symptoms of hypothermia and pigmentation in both animal models. Mast cells that secrete allergic mediators are key regulators on allergic inflammation. Tyrosol dose-dependently decreased mast cell degranulation and expression of inflammatory cytokines. Intracellular calcium levels and activation of inhibitor of κB kinase (IKK) regulate cytokine expression and degranulation. Tyrosol blocked calcium influx and phosphorylation of the IKK complex. To define the molecular target for tyrosol, various signaling proteins involved in mast cell activation such as Lyn, Syk, phosphoinositide 3-kinase (PI3K), and Akt were examined. Our results showed that PI3K could be a molecular target for tyrosol in mast cells. Taken together, these findings indicated that tyrosol has anti-allergic inflammatory effects by inhibiting the degranulation of mast cells and expression of inflammatory cytokines; these effects are mediated via PI3K. Therefore, we expect tyrosol become a potential therapeutic candidate for allergic inflammatory disorders.

  14. Mapping IgE-binding epitopes of Ric c 1 and Ric c 3, allergens from Ricinus communis, by mast cell degranulation assay.

    PubMed

    Felix, S P; Mayerhoffer, R O; Damatta, R A; Verícimo, M A; Nascimento, V V; Machado, O L T

    2008-04-01

    Ric c 1 and Ric c 3 are the major castor bean allergens. In order to identify continuous IgE-epitopes in Ric c 1 and Ric c 3, pools of sera from rats immunized with a pool of 2S albumin from these seeds, Ric c 1 and Ric c 3 overlapping synthetic peptides, were used to screen for IgE-binding epitopes. The allergenic properties were monitored by mast cell degranulation assays, histamine quantification and human-IgE binding. Large and small chains isolated from these proteins present allergenic properties. Four continuous epitopes were identified in Ric c 3 and two in Ric c 1. This knowledge may allow the induction of protective antibody responses to antagonize the IgE recognition.

  15. Intermittent and graded exercise effects on NK cell degranulation markers LAMP-1/LAMP-2 and CD8(+)CD38(+) in chronic fatigue syndrome/myalgic encephalomyelitis.

    PubMed

    Broadbent, Suzanne; Coutts, Rosanne

    2017-03-01

    There is substantial evidence of immune system dysfunction in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) but little is understood of exercise training effects on lymphocyte function in this illness. This study investigated whether graded and intermittent exercise improved CD8(+) lymphocyte activation and natural killer cell degranulation markers compared to no exercise. Twenty-four chronic fatigue syndrome (CFS) patients (50.2 ± 10 year) were randomized to graded exercise (GE), intermittent exercise (IE) or usual care (UC) groups; a control group (CTL) of 18 matched sedentary non-CFS/ME participants were included for immunological variable comparisons. Main outcome measures were pre- and postintervention expression of CD3(+)CD8(+)CD38(+) and CD3(-)CD16(+)56(+)CD107a(+) (LAMP-1) CD107b(+) (LAMP-2) and aerobic exercise capacity. The postintervention percentage of NK cells expressing LAMP-1 and -2 was significantly higher in IE compared to UC, and higher in GE compared to UC and CTL LAMP-1 and LAMP-2 expression (absolute numbers and percent positive) increased significantly pre-to-postintervention for both GE and IE Preintervention, the absolute number of CD8(+)CD38(+) cells was significantly lower in CTL compared to UC and IE There were no significant pre- to postintervention changes in CD8(+)CD38(+) expression for any group. Aerobic exercise capacity was significantly improved by GE and IE Twelve weeks of GE and IE increased the expression of NK cell activation and degranulation markers, suggesting enhanced immunosurveillance. Low-intensity exercise may also reduce CD8(+)CD38(+) expression, a marker of inflammation. Both GE and IE improved exercise capacity without worsening CFS/ME symptoms, and more robust trials of these exercise modalities are warranted.

  16. Antiallergic and antiasthmatic effects of a novel enhydrazinone ester (CEE-1): inhibition of activation of both mast cells and eosinophils.

    PubMed

    Ezeamuzie, Charles I; El-Hashim, Ahmed Z; Renno, Waleed M; Edafiogho, Ivan O

    2014-08-01

    Activation of mast cells and eosinophils is a fundamental process in the pathophysiology of allergic diseases. We have previously reported that the novel enhydrazinone ester CEE-1 (ethyl 4-phenylhydrazinocyclohex-3-en-2-oxo-6-phenyl-1-oate) possesses potent anti-inflammatory activity. We have now tested whether the compound also possesses antiallergic and antiasthmatic effects in vitro and in vivo. The compound significantly inhibited degranulation and leukotriene C4 (LTC4) release from activated human eosinophils, as well as IgE-dependent degranulation and LTC4 release from passively sensitized rat basophilic leukemia cells and bone marrow-derived mouse mast cells. In human eosinophils, the drug was more potent in inhibiting degranulation than LTC4 release {IC50 = 0.4 μM [confidence interval (CI): 0.1-0.9] versus 3.8 μM (CI: 0.9-8.3)}, whereas in mast cells the reverse was essentially the case. The drug did not affect stimulus-induced calcium transients in eosinophils but significantly inhibited early phosphorylation of extracellular signal-regulated kinases 1/2 and p38-mitogen-activated protein kinases (MAPK). In vivo, topical application of 4.5-15 mg/kg of the compound significantly inhibited allergen-induced passive cutaneous anaphylaxis in mice. Similarly, in the mouse asthma model, the intranasal administration of 6.5-12.5 mg/kg of the compound significantly inhibited bronchial inflammation and eosinophil accumulation in bronchial lavage fluid, as well as abolishing airway hyper-responsiveness to methacholine. These results show that CEE-1 inhibits the activation of both mast cells and eosinophils in vitro, probably by blocking MAPK-activation pathways, and that these effects are translated into antiallergic and antiasthmatic effects in vivo. The compound, therefore, has potential application in the treatment of asthma and other allergic diseases.

  17. Mechanism of photobiological effects of psoralens: the involvement of photo-oxidized psoralens as reactive intermediate species in induction of photosensitized hemolysis and skin erythema

    NASA Astrophysics Data System (ADS)

    Lysenko, Eugene P.; Kyagova, Alla A.; Potapenko, Alexander Y.

    2002-07-01

    Psoralens combined with UVA irradiation are used for the treatment of skin and autoimmune diseases. In the present paper the involvement of psoralen photooxidation products (POP) into induction of PUVA-erythema was studied. Under low fluence rate (LFR) UVA-irradiation and/or at low psoralen concentrations POP-products were predominantly formed, which were detected by spin trp method and possessed immunosuppressive activity. Under high fluence rate (HFR) UVA-irradiation and/or at high psoralen concentrations POP2-products were predominantly formed, which could be detected by Fe(II)-induced chemiluminescence and possessed hemolytic activity. Both PUVA- and POP-induced hemolysis of erythrocytes as well as PUVA-erythema were strongly activated with the increase in UVA-fluence rate. Both LFR and HFR PUVA-hemolysis as well as POP-hemolysis were strongly activated by Fe(II)-ions, bivalent cation chelators produced different effects on these processes depending on UVA fluence rate. Ethylenediaminetetraacetate (EDTA), and o- fenanthroline were found to inhibit LFT PUVA-erythema and enhanced HFR PUVA-erythema. Similar regulatory effects of EDTA were found for PUVA- and POP-induced hemolysis. EDTA inhibited LFT PUVA-hemolysis and activated HFR PUVA- and POP-hemolysis that suggests a participation of POP1- products in induction of LFR PUVA-hemolysis and LFT PUVA- erythema and POP2-products in induction of HFR PUVA- hemolysis and HFR PUVA-erythema.

  18. Salvinorin A Inhibits Airway Hyperreactivity Induced by Ovalbumin Sensitization.

    PubMed

    Rossi, Antonietta; Caiazzo, Elisabetta; Bilancia, Rossella; Riemma, Maria A; Pagano, Ester; Cicala, Carla; Ialenti, Armando; Zjawiony, Jordan K; Izzo, Angelo A; Capasso, Raffaele; Roviezzo, Fiorentina

    2016-01-01

    Salvinorin A, a neoclerodane diterpene isolated from Salvia divinorum, exerts a number of pharmacological actions which are not solely limited to the central nervous system. Recently it has been demonstrated that Salvinorin A inhibits acute inflammatory response affecting leukotriene (LT) production. Since LTs are potent lipid mediators implicated in allergic diseases, we evaluated the effect of Salvinorin A on allergic inflammation and on airways following sensitization in the mouse. Mice were sensitized with s.c. injection of ovalbumin (OVA) on days 1 and 8. Sensitized mice received on days 9 and 12 on the shaved dorsal surface air administration to induce the development of the air-pouches. On day 15 animals were challenged by injection of OVA into the air-pouch. Salvinorin A, administered (10 mg/kg) before each allergen exposure, significantly reduced OVA-induced LT increase in the air pouch. This effect was coupled to a reduction in cell recruitment and Th2 cytokine production. In another set of experiments, mice were sensitized with OVA and both bronchial reactivity and pulmonary inflammation were assessed. Salvinorin A abrogated bronchial hyperreactivity and interleukin (IL)-13 production, without effect on pulmonary inflammation. Indeed cell infiltration and peribronchial edema were still present following diterpenoid treatment. Similarly, pulmonary IL-4 and plasmatic IgE levels were not modulated. Conversely, Salvinorin A significantly reduced LTC4 production in the lung of sensitized mice. Finally mast cell activity was evaluated by means of toluidine blue staining. Data obtained evidenced that Salvinorin A significantly inhibited mast cell degranulation in the lung. Our study demonstrates that Salvinorin A inhibits airway hyperreactivity induced by sensitization by inhibition of LT production and mast cell degranulation. In conclusion Salvinorin A could represent a promising candidate for drug development in allergic diseases such as asthma.

  19. Salvinorin A Inhibits Airway Hyperreactivity Induced by Ovalbumin Sensitization

    PubMed Central

    Rossi, Antonietta; Caiazzo, Elisabetta; Bilancia, Rossella; Riemma, Maria A.; Pagano, Ester; Cicala, Carla; Ialenti, Armando; Zjawiony, Jordan K.; Izzo, Angelo A.; Capasso, Raffaele; Roviezzo, Fiorentina

    2017-01-01

    Salvinorin A, a neoclerodane diterpene isolated from Salvia divinorum, exerts a number of pharmacological actions which are not solely limited to the central nervous system. Recently it has been demonstrated that Salvinorin A inhibits acute inflammatory response affecting leukotriene (LT) production. Since LTs are potent lipid mediators implicated in allergic diseases, we evaluated the effect of Salvinorin A on allergic inflammation and on airways following sensitization in the mouse. Mice were sensitized with s.c. injection of ovalbumin (OVA) on days 1 and 8. Sensitized mice received on days 9 and 12 on the shaved dorsal surface air administration to induce the development of the air-pouches. On day 15 animals were challenged by injection of OVA into the air-pouch. Salvinorin A, administered (10 mg/kg) before each allergen exposure, significantly reduced OVA-induced LT increase in the air pouch. This effect was coupled to a reduction in cell recruitment and Th2 cytokine production. In another set of experiments, mice were sensitized with OVA and both bronchial reactivity and pulmonary inflammation were assessed. Salvinorin A abrogated bronchial hyperreactivity and interleukin (IL)-13 production, without effect on pulmonary inflammation. Indeed cell infiltration and peribronchial edema were still present following diterpenoid treatment. Similarly, pulmonary IL-4 and plasmatic IgE levels were not modulated. Conversely, Salvinorin A significantly reduced LTC4 production in the lung of sensitized mice. Finally mast cell activity was evaluated by means of toluidine blue staining. Data obtained evidenced that Salvinorin A significantly inhibited mast cell degranulation in the lung. Our study demonstrates that Salvinorin A inhibits airway hyperreactivity induced by sensitization by inhibition of LT production and mast cell degranulation. In conclusion Salvinorin A could represent a promising candidate for drug development in allergic diseases such as asthma. PMID

  20. Brain-derived mast cells could mediate histamine-induced inhibition of food intake in neonatal chicks.

    PubMed

    Kawakami, S; Bungo, T; Ohgushi, A; Ando, R; Shimojo, M; Masuda, Y; Denbow, D M; Furuse, M

    2000-02-28

    In the present study, the effect of intracerebroventricular (i.c.v.) administration of histamine on food intake of neonatal chicks was examined over 2 h. Histamine (100, 200 or 400 nmol, respectively) was injected in the lateral ventricle of 2-day-old chicks, and cumulative food intakes were measured. i.c.v. injection of histamine significantly inhibited food intake in a dose-dependent manner. In addition, compound 48/80, which causes degranulation of mast cells and release of histamine, or thioperamide, which is an antagonist of the histamine H3 autoreceptor and increases histamine release from histaminergic nerve terminals, was injected i.c.v. to clarify whether mast cell- or neuron-derived histamine in the central nervous system of chicks is essential to the feeding inhibition. Central administration of compound 48/80 inhibited food intake with a dose-dependent manner, but thioperamide had no effect on feeding. An inhibitor of mast cell degranulation, sodium cromoglycate, somewhat attenuated food intake inhibited by compound 48/80. These results suggest that brain-derived mast cells could be a major source of histamine in the inhibition of food intake of neonatal chicks.

  1. Mature eosinophils stimulated to develop in human-cord blood mononuclear cell cultures supplemented with recombinant human interleukin-5. II. Vesicular transport of specific granule matrix peroxidase, a mechanism for effecting piecemeal degranulation.

    PubMed Central

    Dvorak, A. M.; Ackerman, S. J.; Furitsu, T.; Estrella, P.; Letourneau, L.; Ishizaka, T.

    1992-01-01

    The mechanism of piecemeal degranulation by human eosinophils was investigated. Mature eosinophils that developed in rhIL-5-containing conditioned media from cultured human cord blood mononuclear cells were prepared for ultrastructural studies using a combined technique to image eosinophil peroxidase by cytochemistry in the same sections on which postembedding immunogold was used to demonstrate Charcot-Leyden crystal protein. Vesicular transport of eosinophil peroxidase from the specific granule matrix compartment to the cell surface was associated with piecemeal degranulation. This process involved budding of eosinophil peroxidase-loaded vesicles and tubules from specific granules. Some eosinophil peroxidase that was released from eosinophils remained bound to the cell surface; some was free among the cultured cells. Macrophages and basophils bound the released eosinophil peroxidase to their plasma membranes, internalized it in endocytotic vesicles, and stored it in their respective phagolysosomes and secretory granules. Charcot-Leyden crystal protein was diffusely present in the nucleus and cytoplasm of IL-5-stimulated mature eosinophils. Extensive amounts were generally present in granule-poor and subplasma membrane areas of the cytoplasm in contrast to eosinophil peroxidase, which was secreted and bound to the external surface of eosinophil plasma membranes. These studies establish vesicular transport as a mechanism for emptying the specific eosinophil granule matrix compartment during IL-5-associated piecemeal degranulation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 PMID:1562046

  2. Estrogen inhibits mast cell chymase release to prevent pressure overload-induced adverse cardiac remodeling.

    PubMed

    Li, Jianping; Jubair, Shaiban; Janicki, Joseph S

    2015-02-01

    Estrogen regulation of myocardial chymase and chymase effects on cardiac remodeling are unknown. To test the hypothesis that estrogen prevents pressure overload-induced adverse cardiac remodeling by inhibiting mast cell (MC) chymase release, transverse aortic constriction or sham surgery was performed in 7-week-old intact and ovariectomized (OVX) rats. Three days before creating the constriction, additional groups of OVX rats began receiving 17β-estradiol, a chymase inhibitor, or a MC stabilizer. Left ventricular function, cardiomyocyte size, collagen volume fraction, MC density and degranulation, and myocardial and plasma chymase levels were assessed 18 days postsurgery. Aortic constriction resulted in ventricular hypertrophy in intact and OVX groups, whereas collagen volume fraction was increased only in OVX rats. Chymase protein content was increased by aortic constriction in the intact and OVX groups, with the magnitude of the increase being greater in OVX rats. MC density and degranulation, plasma chymase levels, and myocardial active transforming growth factor-β1 levels were increased by aortic constriction only in OVX rats. Estrogen replacement markedly attenuated the constriction-increased myocardial chymase, MC density and degranulation, plasma chymase, and myocardial active transforming growth factor-β1, as well as prevented ventricular hypertrophy and increased collagen volume fraction. Chymostatin attenuated the aortic constriction-induced ventricular hypertrophy and collagen volume fraction in the OVX rats similar to that achieved by estrogen replacement. Nedocromil yielded similar effects, except for the reduction of chymase content. We conclude that the estrogen-inhibited release of MC chymase is responsible for the cardioprotection against transverse aortic constriction-induced adverse cardiac remodeling.

  3. Sinomenine potentiates P815 cell degranulation via upregulation of Ca2+ mobilization through the Lyn/PLCγ/IP3R pathway.

    PubMed

    Wang, Nan; Liu, Rui; Liu, Yanping; Zhang, Ruirui; He, Langchong

    2016-12-01

    Mast cells are vital mediators of drug allergy and, therefore, studying the relationship between drug allergy and mast cells is essential. Sinomenine is the principal active component of Sinomenium acutum, which has anti-inflammatory and anti-immune effects, and is used to treat various rheumatoid diseases. However, allergic responses to sinomenine are frequently reported. Therefore, this study assessed the effects of sinomenine on mast cell activation to characterize its allergic effects and the underlying mechanisms. Enzyme-linked immunosorbent assay (ELISA), western blot analyses, and degranulation assays were performed to measure pro-inflammatory and allergic mediators in P815 cells. The allergenic effects of sinomenine were also determined in mice by using active general anaphylaxis (ASA). The results indicated that sinomenine induced inositol-1,4,5-trisphosphate (IP3) production and the release of histamine, interleukin (IL)-6, and endoplasmic reticulum Ca(2+) in P815 cells. Furthermore, sinomenine upregulated the phosphorylation of sarcoma (Src), phospholipase C (PLC)-γ1, and IP3 receptor (R). Therefore, sinomenine induced concentration-dependent mast cell activation directly in vitro Furthermore, our in vivo data identified an appropriate intravenous dose that did not induce these allergic effects, thereby providing information for the potential safe clinical use of sinomenine.

  4. Chronic Insulin Exposure Induces ER Stress and Lipid Body Accumulation in Mast Cells at the Expense of Their Secretory Degranulation Response

    PubMed Central

    Balajadia, Januaria; Shimoda, Lori M. N.; Sung, Carl; Turner, Helen

    2015-01-01

    Lipid bodies (LB) are reservoirs of precursors to inflammatory lipid mediators in immunocytes, including mast cells. LB numbers are dynamic, increasing dramatically under conditions of immunological challenge. We have previously shown in vitro that insulin-influenced lipogenic pathways induce LB biogenesis in mast cells, with their numbers attaining steatosis-like levels. Here, we demonstrate that in vivo hyperinsulinemia resulting from high fat diet is associated with LB accumulation in murine mast cells and basophils. We characterize the lipidome of purified insulin-induced LB, and the shifts in the whole cell lipid landscape in LB that are associated with their accumulation, in both model (RBL2H3) and primary mast cells. Lipidomic analysis suggests a gain of function associated with LB accumulation, in terms of elevated levels of eicosanoid precursors that translate to enhanced antigen-induced LTC4 release. Loss-of-function in terms of a suppressed degranulation response was also associated with LB accumulation, as were ER reprogramming and ER stress, analogous to observations in the obese hepatocyte and adipocyte. Taken together, these data suggest that chronic insulin elevation drives mast cell LB enrichment in vitro and in vivo, with associated effects on the cellular lipidome, ER status and pro-inflammatory responses. PMID:26263026

  5. Cutaneous necrotizing venulitis: a sequential analysis of the morphological alterations occurring after mast cell degranulation in a patient with a unique syndrome.

    PubMed Central

    Soter, N A; Mihm, M C; Dvorak, H F; Austen, K F

    1978-01-01

    An unusual patient, with dermal nodules, flexion contractures of the fingers and toes, cold-induced urticaria, dermographism and serum hypocomplementaemia, had necrotizing cutaneous venulitis underlying the spontaneous lesions. Since necrotizing cutaneous venulitis could be experimentally induced by the physical stimuli of cold or trauma, the time-course of histopathological events was documented in the skin of this patient. The histopathological alterations were studied in 1 micron thick, Epon-embedded skin biopsy specimens over an interval of 6 days. The early massive degranulation of the mast cells was followed by the sequential infiltration of neutrophilic, eosinophilic and basophilic polymorphonuclear leucocytes, by the development of venular endothelial cell necrosis and by the deposition of fibrin. The persistent serum hypocomplementaemia involved the classic activating and amplification pathways. It seems possible that the unusual combination of pathobiological processes involving the mast cells and the complement system in this patient has created a unique syndrome, in which venules are damaged and the sheaths of the extensor tendons of the hands and feet become affected in time. Images FIG. 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 PMID:668192

  6. Probing the mystery of Chinese medicine meridian channels with special emphasis on the connective tissue interstitial fluid system, mechanotransduction, cells durotaxis and mast cell degranulation

    PubMed Central

    Fung, Peter Chin Wan

    2009-01-01

    This article hypothesizes that the Chinese medicine meridian system is a special channel network comprising of skin with abundant nerves and nociceptive receptors of various types, and deeper connective tissues inside the body with the flowing interstitial fluid system. These meridian channels provide efficient migratory tracks mainly due to durotaxis (also including chemotaxis) for mast cells, fibroblasts and other cells to migrate and carry out a number of physiological functions. Acupuncture acting on meridian channel causes cytoskeletal remodeling through mechanotransduction, leading to regulation of gene expression and the subsequent production of related proteins. Also, stimulation on cell surface can trigger Ca2+ activities, resulting in a cascade of intra- and inter-cellular signaling. Moreover, nerve endings in the meridian channels interact with mast cells and induce the degranulation of these cells, leading to the release of many specific biomolecules needed for homeostasis, immune surveillance, wound healing and tissue repair. Acupoint along a meridian channel is a functional site to trigger the above functions with specificity and high efficiency. PMID:19480699

  7. Platelet adhesion and degranulation induce pro-survival and pro-angiogenic signalling in ovarian cancer cells.

    PubMed

    Egan, Karl; Crowley, Darragh; Smyth, Paul; O'Toole, Sharon; Spillane, Cathy; Martin, Cara; Gallagher, Michael; Canney, Aoife; Norris, Lucy; Conlon, Niamh; McEvoy, Lynda; Ffrench, Brendan; Stordal, Britta; Keegan, Helen; Finn, Stephen; McEneaney, Victoria; Laios, Alex; Ducrée, Jens; Dunne, Eimear; Smith, Leila; Berndt, Michael; Sheils, Orla; Kenny, Dermot; O'Leary, John

    2011-01-01

    Thrombosis is common in ovarian cancer. However, the interaction of platelets with ovarian cancer cells has not been critically examined. To address this, we investigated platelet interactions in a range of ovarian cancer cell lines with different metastatic potentials [HIO-80, 59M, SK-OV-3, A2780, A2780cis]. Platelets adhered to ovarian cancer cells with the most significant adhesion to the 59M cell line. Ovarian cancer cells induced platelet activation [P-selectin expression] in a dose dependent manner, with the most significant activation seen in response to the 59M cell line. The platelet antagonists [cangrelor, MRS2179, and apyrase] inhibited 59M cell induced activation suggesting a P2Y12 and P2Y1 receptor mediated mechanism of platelet activation dependent on the release of ADP by 59M cells. A2780 and 59M cells potentiated PAR-1, PAR-4, and TxA2 receptor mediated platelet activation, but had no effect on ADP, epinephrine, or collagen induced activation. Analysis of gene expression changes in ovarian cancer cells following treatment with washed platelets or platelet releasate showed a subtle but valid upregulation of anti-apoptotic, anti-autophagy pro-angiogenic, pro-cell cycle and metabolic genes. Thus, ovarian cancer cells with different metastatic potential adhere and activate platelets differentially while both platelets and platelet releasate mediate pro-survival and pro-angiogenic signals in ovarian cancer cells.

  8. Inhibition of aspirin-induced bronchoconstriction by sodium cromoglycate inhalation.

    PubMed Central

    Martelli, N A; Usandivaras, G

    1977-01-01

    Five patients with asthma and severe aspirin hypersensitivity were challenged on separate days with increasing doses of aspirin given by mouth, starting with 5 mg, until a reduction in FEV1 greater than 15% was obtained. Sodium cromoglycate in doses of 20-40 mg inhibited the bronchoconstrictive reaction not only when inhaled before the challenge but also after it, at a time when progressive reduction in FEV1 values was taking place. According to these results, it seems reasonable to postulate sequential mast cell degranulation and liberation of mediators of anaphylaxis as the mechanism through which aspirin induces bronchoconstriction in aspirin-sensitive asthmatics. The differences between bronchial provocation tests and oral challenge with aspirin are stressed. PMID:414371

  9. Protein-bound Vaccinium fruit polyphenols decrease IgE binding to peanut allergens and RBL-2H3 mast cell degranulation in vitro.

    PubMed

    Plundrich, Nathalie J; Bansode, Rishipal R; Foegeding, E Allen; Williams, Leonard L; Lila, Mary Ann

    2017-03-15

    Peanut allergy is a worldwide health concern. In this study, the natural binding properties of plant-derived polyphenols to proteins was leveraged to produce stable protein-polyphenol complexes comprised of peanut proteins and cranberry (Vaccinium macrocarpon Ait.) or lowbush blueberry (Vaccinium angustifolium Ait.) pomace polyphenols. Protein-bound and free polyphenols were characterized and quantified by multistep extraction of polyphenols from protein-polyphenol complexes. Immunoblotting was performed with peanut-allergic plasma to determine peanut protein-specific IgE binding to unmodified peanut protein, or to peanut protein-polyphenol complexes. In an allergen model system, RBL-2H3 mast cells were exposed to peanut protein-polyphenol complexes and evaluated for their inhibitory activity on ionomycin-induced degranulation (β-hexosaminidase and histamine). Among the evaluated polyphenolic compounds from protein-polyphenol complex eluates, quercetin, - in aglycone or glycosidic form - was the main phytochemical identified to be covalently bound to peanut proteins. Peanut protein-bound cranberry and blueberry polyphenols significantly decreased IgE binding to peanut proteins at p < 0.05 (38% and 31% decrease, respectively). Sensitized RBL-2H3 cells challenged with antigen and ionomycin in the presence of protein-cranberry and blueberry polyphenol complexes showed a significant (p < 0.05) reduction in histamine and β-hexosaminidase release (histamine: 65.5% and 65.8% decrease; β-hexosaminidase: 60.7% and 45.4% decrease, respectively). The modification of peanut proteins with cranberry or blueberry polyphenols led to the formation of peanut protein-polyphenol complexes with significantly reduced allergenic potential. Future trials are warranted to investigate the immunomodulatory mechanisms of these protein-polyphenol complexes and the role of quercetin in their hypoallergenic potential.

  10. Raft localization of type I Fcε receptor and degranulation of RBL-2H3 cells exposed to decavanadate, a structural model for V2O5.

    PubMed

    Al-Qatati, Abeer; Fontes, Fabio L; Barisas, B George; Zhang, Dongmei; Roess, Deborah A; Crans, Debbie C

    2013-09-07

    Vanadium oxides (VOs) have been identified as low molecular weight sensitizing agents associated with occupational asthma and compromised pulmonary immunocompetence. Symptoms of adult onset asthma result, in part, from increased signal transduction by Type I Fcε receptors (FcεRI) leading to release of vasoactive compounds including histamine from mast cells. Exposure to (VOs) typically occurs in the form of particles which are insoluble. Upon contact with water or biological fluids, (VOs) form a series of soluble oxoanions, one of which is decavanadate, V10O28(6-) abbreviated V10, which is structurally related to a common vanadium oxide, that is vanadium pentoxide, V2O5. Here we investigate whether V10 may be initiating plasma membrane events associated with activation of FcεRI signal transduction. We show that exposure of RBL-2H3 cells to V10 causes a concentration-dependent increase in degranulation of RBL-2H3 and, in addition, an increase in plasma membrane lipid packing as measured by the fluorescent probe, di-4-ANEPPDHQ. V10 also increases FcεRI accumulation in low-density membrane fragments, i.e., lipid rafts, which may facilitate FcεRI signaling. To determine whether V10 effects on plasma membrane lipid packing were similarly observed in Langmuir monolayers formed from dipalmitoylphosphatidylcholine (DPPC), the extent of lipid packing in the presence and absence of V10 and vanadate was compared. V10 increased the surface area of DPPC Langmuir monolayers by 6% and vanadate decreased the surface area by 4%. These results are consistent with V10 interacting with this class of membrane lipids and altering DPPC packing.

  11. Sinomenine potentiates degranulation of RBL-2H3 basophils via up-regulation of phospholipase A2 phosphorylation by Annexin A1 cleavage and ERK phosphorylation without influencing on calcium mobilization.

    PubMed

    Huang, Lufen; Li, Ting; Zhou, Hua; Qiu, Ping; Wu, Jianlin; Liu, Liang

    2015-10-01

    Sinomenine (SIN), an alkaloid derived from the Chinese medicinal plant Sinomenium acutum, is the major component of Zhengqing Fongtong Ning (ZQFTN), a pharmaceutical drug produced by Hunan Zhengqing Pharmaceutical Co. Ltd. in China for the treatment of rheumatoid arthritis and other autoimmune diseases. Some clinic reports indicate that ZQFTN may induce an anaphylactic reaction via potentiating the degranulation of immune cells. In the current study, we aimed to examine whether SIN is capable of inducing the degranulation of basophilic leukemia 2H3 (RBL-2H3) cells to elucidate how the anaphylactic reaction occurs. The results revealed that SIN could up-regulate β-hexosaminidase levels in RBL-2H3 cells without significant cytotoxicity, suggesting that SIN could induce the degranulation of RBL-2H3 cells. Furthermore, SIN increased the release of prostaglandin D2 (PGD2) and prostaglandin E2 (PGE2) in RBL-2H3 cells via promoting the expression of phosphorylated-extracellular signal-regulated kinase (P-ERK), the cleavage of Annexin A1 (ANXA1), and phosphorylated-cytosolic phospholipase A2 (P-cPLA2), as well as cyclooxygenase-2 (COX-2). The ERK inhibitor, PD98059, significantly attenuated the up-regulatory effect of SIN on cPLA2 phosphorylation. Interestingly, SIN did not significantly increase Ca(2+) influx in the cells. These findings not only explored the anaphylactic reaction and underlying mechanism of ZQFTN in RBL-2H3 cells, but may promote the development of relevant strategies for overcoming the adverse effects of the drug.

  12. Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts.

    PubMed

    Nielsen, Natasja; Pascal, Veronique; Fasth, Andreas E R; Sundström, Yvonne; Galsgaard, Elisabeth D; Ahern, David; Andersen, Martin; Baslund, Bo; Bartels, Else M; Bliddal, Henning; Feldmann, Marc; Malmström, Vivianne; Berg, Louise; Spee, Pieter; Söderström, Kalle

    2014-08-01

    Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and synovial hyperplasia leading to progressive joint destruction. Fibroblast-like synoviocytes (FLS) are central components of the aggressive, tumour-like synovial structure termed pannus, which invades the joint space and cartilage. A distinct natural killer (NK) cell subset expressing the inhibitory CD94/NKG2A receptor is present in RA synovial fluid. Little is known about possible cellular interactions between RA-FLS and NK cells. We used cultured RA-FLS and the human NK cell line Nishi, of which the latter expresses an NK receptor repertoire similar to that of NK cells in RA synovial fluid, as an in vitro model system of RA-FLS/NK cell cross-talk. We show that RA-FLS express numerous ligands for both activating and inhibitory NK cell receptors, and stimulate degranulation of Nishi cells. We found that NKG2D, DNAM-1, NKp46 and NKp44 are the key activating receptors involved in Nishi cell degranulation towards RA-FLS. Moreover, blockade of the interaction between CD94/NKG2A and its ligand HLA-E expressed on RA-FLS further enhanced Nishi cell degranulation in co-culture with RA-FLS. Using cultured RA-FLS and the human NK cell line Nishi as an in vitro model system of RA-FLS/NK cell cross-talk, our results suggest that cell-mediated cytotoxicity of RA-FLS may be one mechanism by which NK cells influence local joint inflammation in RA.

  13. Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts

    PubMed Central

    Nielsen, Natasja; Pascal, Veronique; Fasth, Andreas E R; Sundström, Yvonne; Galsgaard, Elisabeth D; Ahern, David; Andersen, Martin; Baslund, Bo; Bartels, Else M; Bliddal, Henning; Feldmann, Marc; Malmström, Vivianne; Berg, Louise; Spee, Pieter; Söderström, Kalle

    2014-01-01

    Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and synovial hyperplasia leading to progressive joint destruction. Fibroblast-like synoviocytes (FLS) are central components of the aggressive, tumour-like synovial structure termed pannus, which invades the joint space and cartilage. A distinct natural killer (NK) cell subset expressing the inhibitory CD94/NKG2A receptor is present in RA synovial fluid. Little is known about possible cellular interactions between RA-FLS and NK cells. We used cultured RA-FLS and the human NK cell line Nishi, of which the latter expresses an NK receptor repertoire similar to that of NK cells in RA synovial fluid, as an in vitro model system of RA-FLS/NK cell cross-talk. We show that RA-FLS express numerous ligands for both activating and inhibitory NK cell receptors, and stimulate degranulation of Nishi cells. We found that NKG2D, DNAM-1, NKp46 and NKp44 are the key activating receptors involved in Nishi cell degranulation towards RA-FLS. Moreover, blockade of the interaction between CD94/NKG2A and its ligand HLA-E expressed on RA-FLS further enhanced Nishi cell degranulation in co-culture with RA-FLS. Using cultured RA-FLS and the human NK cell line Nishi as an in vitro model system of RA-FLS/NK cell cross-talk, our results suggest that cell-mediated cytotoxicity of RA-FLS may be one mechanism by which NK cells influence local joint inflammation in RA. PMID:24673109

  14. Macelignan inhibits histamine release and inflammatory mediator production in activated rat basophilic leukemia mast cells.

    PubMed

    Han, Young Sun; Kim, Myung-Suk; Hwang, Jae-Kwan

    2012-10-01

    Type I allergy is characterized by the release of granule-associated mediators, lipid-derived substances, cytokines, and chemokines by activated mast cells. To evaluate the anti-allergic effects of macelignan isolated from Myristica fragrans Houtt., we determined its ability to inhibit calcium (Ca(2+)) influx, degranulation, and inflammatory mediator production in RBL-2 H3 cells stimulated with A23187 and phorbol 12-myristate 13-acetate. Macelignan inhibited Ca(2+) influx and the secretion of β-hexosaminidase, histamine, prostaglandin E(2), and leukotriene C(4); decreased mRNA levels of cyclooxygenase-2, 5-lipoxygenase, interleukin-4 (IL-4), IL-13, and tumor necrosis factor-α; and attenuated phosphorylation of Akt and the mitogen-activated protein kinases extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. These results indicate the potential of macelignan as a type I allergy treatment.

  15. Inactivated pepsin inhibits neutrophil activation by Fcgamma-receptor-dependent and independent stimuli.

    PubMed

    Kustiawan, Iwan; Derksen, Ninotska; Rispens, Theo

    2016-08-01

    Pepsin is widely used to produce F(ab')2 fragments of immunoglobulin G (IgG). In many cases, at least part of the pepsin will remain present in the F(ab')2 preparation, albeit in (irreversibly) inactivated form. Here we report on a potent immunomodulatory effect of irreversibly inactivated pepsin on activated human neutrophils. Degranulation, induced by coated IgG or via cytochalasin B/N-formyl-Met-Leu-Phe, was measured by quantifying elastase release, and was found to be inhibited in a dose-dependent manner by inactivated pepsin. Since a number of intravenous immunoglobulin (IVIg) products are also treated by limited digestion with pepsin, we investigated if pepsin would be present in quantities large enough to inhibit neutrophil activation. The amounts of pepsin detected in three different pepsin-treated IVIg products were found to be too low to induce an effect, at least in an in vitro setting.

  16. The Inhibition of Mast Cell Activation of Radix Paeoniae alba Extraction Identified by TCRP Based and Conventional Cell Function Assay Systems

    PubMed Central

    Fu, Huiying; Cheng, Hongqiang; Cao, Gang; Zhang, Xingde; Tu, Jue; Sun, Mingjiao; Mou, Xiaozhou; Shou, Qiyang; Ke, Yuehai

    2016-01-01

    Chinese herbs have long been used to treat allergic disease, but recently the development was greatly impeded by the lack of good methods to explore the mechanism of action. Here, we showed the effects of Chinese herb Radix Paeoniae alba were identified and characterized by a mast cell activation assay that involves electronic impedance readouts for dynamic monitoring of cellular responses to produce time-dependent cell responding profiles (TCRPs), and the anti-allergic activities were further confirmed with various conventional molecular and cell biology tools. We found Radix P. alba can dose-dependently inhibit TCPRs, and have anti-allergic function in vitro and in vivo. Radix P. alba suppressed mast cell degranulation not only inhibiting the translocation of granules to the plasma membrane, but also blocking membrane fusion and exocytosis; and that there may be other anti-allergic components in addition to paeoniflorin. Our results suggest that Radix P. alba regulated mast cell activation with multiple targets, and this approach is also suitable for discovering other mast cell degranulation-targeting Chinese herbs and their potential multi-target mechanisms. PMID:27195739

  17. Inhibition of an Allergen–Antibody Reaction Related to Japanese Cedar Pollinosis Using DNA Aptamers Against the Cry j 2 Allergen

    PubMed Central

    Ogihara, Kazumasa; Savory, Nasa; Abe, Koichi; Yoshida, Wataru; Arakawa, Mitsuru; Asahi, Masahiko; Kamohara, Seika

    2015-01-01

    Japanese cedar pollinosis is one of the most prevalent allergies in Japan. Reducing the allergen content of pollen plays a major role in the alleviation of allergy symptoms. Aptamers, oligonucleotides with an affinity for specific molecules, have great potential for reducing allergic activity. In this study, we report that the anti-Cry j 2 aptamers, CJ2-04 and CJ2-08, inhibited allergen–antibody reactions between Cry j 2, one of the major allergens in Japanese cedar pollen, and immunoglobulin E in serum collected from a patient with Japanese cedar pollinosis. In addition, the suppression of Ca2+ mobilization in basophils, which is related to degranulation, was observed in samples preincubated with either of these DNA aptamers. This study indicates that anti-Cry j 2 aptamers may inhibit allergen–antibody reactions and suppress the induction of Japanese cedar pollinosis, possibly leading to a novel external defense against this and other types of allergens. PMID:26484654

  18. Combined exposure of peripubertal male rats to the endocrine-disrupting compound atrazine and power-frequency electromagnetic fields causes degranulation of cutaneous mast cells: a new toxic environmental hazard?

    PubMed

    Rajkovic, Vesna; Matavulj, Milica; Johansson, Olle

    2010-08-01

    The effects of single and combined treatments of the endocrine-disrupting compound atrazine and the power-frequency electromagnetic fields (EMFs) were investigated on cutaneous mast cells in juvenile/peripubertal male Wistar rats. Animals were divided into six groups: (1) 4 h/day exposure to EMFs (50 Hz), (2) 20 mg/kg of body weight (bw) of atrazine, (3) 200 mg/kg bw of atrazine, (4) EMFs with 20 mg/kg bw of atrazine, (5) EMFs with 200 mg/kg bw of atrazine, and (6) control. Both the atrazine and the combined treatments, but not the single EMF exposure, increased the number of degranulated mast cells. Statistically significant differences were demonstrated between the control and both of the combined treatments (p<0.01 and p<0.001, respectively). Additionally, low and high doses of atrazine combined with the EMFs were found significantly different when compared to the EMF group alone (both at p<0.001). Considering the biological importance of mast cells in cutaneous immune reactions, future studies should reveal whether combined exposures to chemical and physical environmental agents pose a serious health risk.

  19. IgE–mediated mast cell responses are inhibited by thymol-mediated, activation-induced cell death in skin inflammation

    PubMed Central

    Wechsler, Joshua B.; Hsu, Chia-Lin; Bryce, Paul J.

    2014-01-01

    Background Mast cells play a critical role in inflammatory skin diseases through releasing pro-inflammatory mediators; however, few therapies directly target these cells. In 1878, the use of topical Thymol, a now recognized potent agonist for Transient Receptor Potential (TRP) channels, was first described to treat eczema and psoriasis. Objective We sought to determine the mechanisms through which thymol may alter skin inflammation. Methods We examined the effect of topical thymol on IgE-dependent responses using a mast cell–dependent passive cutaneous anaphylaxis (PCA) model as well as in vitro cultured mast cells. Results Thymol dose-dependently inhibited PCA when administered topically 24 hours prior to antigen challenge but provoked an ear swelling response directly on application. This direct effect was associated with local mast cell degranulation and was absent in histamine-deficient mice. However, unlike with PCA responses, there was no late phase swelling. In vitro, thymol directly trigged calcium flux in mast cells via TRP-channel activation, along with degranulation and cytokine transcription. However, no cytokine protein was produced. Instead, thymol induced a significant increase in apoptotic cell death that was seen both in vitro and in vivo. Conclusions We propose that the efficacy of thymol in reducing IgE-dependent responses is through promotion of activation-induced apoptotic cell death of mast cells and that this likely explains the clinical benefits observed in early clinical reports. PMID:24486068

  20. Cheonggukjang Ethanol Extracts Inhibit a Murine Allergic Asthma via Suppression of Mast Cell-Dependent Anaphylactic Reactions

    PubMed Central

    Bae, Min-Jung; Shin, Hee Soon; See, Hye-Jeong

    2014-01-01

    Abstract Cheonggukjang (CGJ), a traditional Korean fermented soybean food, exerts immunomodulatory effects. Asthma is the most common chronic allergic disease to be associated with immune response to environmental allergens. In the pathogenesis of asthma, histamine is one of the important inflammatory mediators released from granules of mast cells. In this study, we evaluated the therapeutic effect of CGJ on a mouse model of ovalbumin (OVA)-induced asthma via the suppression of histamine release. C57BL/6 mice were sensitized by intraperitoneal injection of OVA or a phosphate-buffered saline (PBS) control and then challenged with OVA inhalation. Mice were treated intraperitoneally with either 70% ethanol-extracted CGJ (CGJE) (100 mg/kg/day) or equivalent PBS. Asthma-related inflammation was assessed by bronchoalveolar lavage fluid cell counts and histopathological and immunohistochemical analysis of lung tissues. To elucidate the mechanisms of asthma inhibition by CGJE treatment, we also examined degranulation and histamine release of compound 48/80-induced rat peritoneal mast cells (RPMCs). Treatment with CGJE downregulated the number of eosinophils and monocytes in the lungs of mice challenged with OVA and suppressed histopathological changes, such as eosinophil infiltration, mucus accumulation, goblet cell hyperplasia, and collagen fiber deposits. Moreover, CGJE alleviated compound 48/80-induced mast cell degranulation and histamine release from RPMCs through inhibition of calcium (Ca2+) uptake as well as ear swelling by infiltration of inflammatory cells. These findings demonstrated that CGJE can be used as an antiasthmatic dietary supplements candidate for histamine-mediated asthma. PMID:24456365

  1. Spiraeoside inhibits mast cells activation and IgE-mediated allergic responses by suppressing phospholipase C-γ-mediated signaling.

    PubMed

    Kim, Jung Kuk; Seo, Young-Kyo; Park, Sehoon; Park, Soo-Ah; Lim, Seyoung; Lee, Susie; Kwon, Ohman; Seo, Jeong Kon; Choi, Ung-Kyu; Ryu, Sung Ho; Suh, Pann-Ghill

    2015-06-01

    Mast cells are responsible for IgE-mediated allergic responses through the secretion of various inflammatory cytokines and mediators. Therefore, the pharmacological regulation of mast cell activation is an important goal in the development of novel anti-allergic drugs. In this study, we found that spiraeoside (SP) inhibits mast cell activation and allergic responses in vivo. SP dose-dependently inhibited the degranulation induced by IgE-antigen (Ag) stimulation in RBL-2H3 mast cells without cytotoxic effects. At the molecular level, SP reduced the Ag-induced phosphorylation and subsequent activation of phospholipase C-γ2 (PLC-γ2). Moreover, SP inhibited the phosphorylation of spleen tyrosine kinase (Syk), linker for activation of T cells (LAT), and downstream MAPKs, such as ERK1/2, p38, and JNK, eventually attenuating expression of TNF-α and IL-4. Finally, we found that SP significantly inhibited IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. Taken together, our results strongly suggest that SP suppresses IgE-mediated mast cell activation and allergic responses by inhibiting Lyn-induced PLC-γ2/MAPK signaling in mast cells.

  2. Charybdotoxin is a new member of the K sup + channel toxin family that includes dendrotoxin I and mast cell degranulating peptide

    SciTech Connect

    Schweitz, H.; Bidard, J.N.; Lazdunski, M. ); Maes, P. )

    1989-12-12

    A polypeptide was identified in the venom of the scorpion Leiurus quinquestriatus hebraeus by its potency to inhibit the high affinity binding of the radiolabeled snake venom toxin dendrotoxin I ({sup 125}I-DTX{sub I}) to its receptor site. It has been purified, and its properties investigated by different techniques were found to be similar to those of MCD and DTX{sub I}, two polypeptide toxins active on a voltage-dependent K{sup +} channel. However, its amino acid sequence was determined, and it was shown that this toxin is in fact charybdotoxin (ChTX), a toxin classically used as a specific tool to block one class of Ca{sup 2+}-activated K{sup +} channels. ChTX, DTX{sub I}, and MCD are potent convulsants and are highly toxic when injected intracerebroventricularly in mice. Their toxicities correlate well with their affinities for their receptors in rat brain. These three structurally different toxins release ({sup 3}H)GABA from preloaded synaptosomes, the efficiency order being DTX{sub I} > ChTX > MCD. Both binding and cross-linking experiments of ChTX to rat brain membranes and to the purified MCD/DTX{sub I} binding protein have shown that the {alpha}-subunit of the MCD/DTX{sub I}-sensitive K{sup +} channel protein also contains the ChTX binding sites. Binding sites for DTX{sub I}, MCD, and ChTX are in negative allosteric interaction. The results show that charybdotoxin belongs to the family of toxins which already includes the dendrotoxins and MCD, which are blockers of voltage-sensitive K{sup +} channels. ChTX is clearly not selective for Ca{sup 2+}-activated K{sup +} channel.

  3. Uptake of donor lymphocytes treated with 8-methoxypsoralen and ultraviolet A light by recipient dendritic cells induces CD4{sup +}CD25{sup +}Foxp3{sup +} regulatory T cells and down-regulates cardiac allograft rejection

    SciTech Connect

    Zheng, De-Hua; Dou, Li-Ping; Wei, Yu-Xiang; Du, Guo-Sheng; Zou, Yi-Ping; Song, Ji-Yong; Zhu, Zhi-Dong; Cai, Ming; Qian, Ye-Yong; Shi, Bing-Yi

    2010-05-14

    Extracorporeal photopheresis (ECP) is an effective immunomodulatory therapy and has been demonstrated to be beneficial for graft-vs-host disease and solid-organ allograft rejection. ECP involves reinfusion of a patient's autologous peripheral blood leukocytes treated ex vivo with 8-methoxypsoralen and UVA light radiation (PUVA). Previous studies focused only on ECP treatment of recipient immune cells. Our study is the first to extend the target of ECP treatment to donor immune cells. The results of in vitro co-culture experiments demonstrate uptake of donor PUVA-treated splenic lymphocytes (PUVA-SPs) by recipient immature dendritic cells (DCs). Phagocytosis of donor PUVA-SPs does not stimulate phenotype maturation of recipient DCs. In the same co-culture system, donor PUVA-SPs enhanced production of interleukin-10 and interferon-{gamma} by recipient DCs and impaired the subsequent capability of recipient DCs to stimulate recipient naive T cells. Phagocytosis of donor PUVA-SP (PUVA-SP DCs) by recipient DCs shifted T-cell responses in favor of T helper 2 cells. Infusion of PUVA-SP DCs inhibited cardiac allograft rejection in an antigen-specific manner and induced CD4{sup +}CD25{sup high}Foxp3{sup +} regulatory T cells. In conclusion, PUVA-SP DCs simultaneously deliver the donor antigen and the regulatory signal to the transplant recipient, and thus can be used to develop a novel DC vaccine for negative immune regulation and immune tolerance induction.

  4. Method for decreasing radiation load in puva therapy

    SciTech Connect

    Wolff, K.

    1987-02-10

    An improved method is described for treating a psoriatic subject undergoing treatment with a psoralen in conjection with ultraviolet A radiation of from wavelength of 3200 to 4000 angstroms. The improved method comprises prior to initiation of the treatment, pretreating the subject for a period of from 4 to 10 days with an effective amount of an anti-psoriatic polyene compound, and thereafter initiating the treatment with a psoralen in conjunction with ultraviolet A radiation and continuing the treatment concurrently with the administration of the anti-psoriatic polyene compound.

  5. Anti-allergic properties of the bromeliaceae Nidularium procerum: inhibition of eosinophil activation and influx.

    PubMed

    Vieira-de-Abreu, Adriana; Amendoeira, Fábio C; Gomes, Gleice S; Zanon, Cristiane; Chedier, Luciana M; Figueiredo, Maria Raquel; Kaplan, Maria Auxiliadora C; Frutuoso, Válber S; Castro-Faria-Neto, Hugo C; Weller, Peter F; Bandeira-Melo, Christianne; Bozza, Patrícia T

    2005-12-01

    New therapeutic approaches for the treatment of allergic diseases can be aided by the development of agents capable of regulating eosinophilic leukocytes. Here, we evaluated the anti-allergic properties of a crude extract of the Brazilian bromeliaceae Nidularium procerum, focusing on its effects on allergic eosinophilia. By studying allergic pleurisy in actively sensitized C57Bl/6 mice, we observed that pretreatment with N. procerum (2 mg/kg; i.p.) reduced pleural eosinophil influx triggered by allergen challenge. N. procerum was also able to reduce lipid body numbers found within infiltrating eosinophils, indicating that N. procerum in vivo is able to affect both migration and activation of eosinophils. Consistently, pretreatment with N. procerum blocked pleural eosinophil influx triggered by PAF or eotaxin, key mediators of the development of allergic pleural eosinophilia. The effect of N. procerum was not restricted to eosinophils, since N. procerum also inhibited pleural neutrophil and mononuclear cell influx. Of note, N. procerum failed to alter the acute allergic reaction, characterized by mast cell degranulation, oedema, and cysteinyl leukotriene release. N. procerum also had direct effects on murine eosinophils, since it inhibited both PAF- and eotaxin-induced eosinophil chemotaxis on an in vitro chemotactic assay. Therefore, N. procerum may be a promising anti-allergic therapy, inasmuch as it presents potent anti-eosinophil activity.

  6. Monascus secondary metabolites monascin and ankaflavin inhibit activation of RBL-2H3 cells.

    PubMed

    Chang, Yu-Ying; Hsu, Wei-Hsuan; Pan, Tzu-Ming

    2015-01-14

    Monascus-fermented products have been used as dietary food and traditional medicine due to their beneficial effects on circulation and digestive systems in Asia for thousands of years. Besides, monascin and ankaflavin, secondary metabolites from Monascus-fermented products, have proven anti-inflammatory and immunomodulatory effects. In previous research, monascin and ankaflavin ameliorated ovalbumin-induced airway allergic reaction often used as a type I allergy asthma model. Additionally, mast cells play critical roles in type I allergy. Therefore, RBL-2H3 cells were used as the mast cell model to determine whether the improving effects on asthma of monascin and ankaflavin came from influencing mast cells. PMA and ionomycin are common activators of mast cells because they stimulate the main signaling molecules during mast cell activation. Forty micromolar monascin and ankaflavin inhibited PMA/ionomycin-induced mast cell degranulation and TNF-α secretion through suppressing the phosphorylation of PKC and MAPK family ERK, JNK, and p38. Consequently, monascin and ankaflavin affected the activation of mast cells and may have the potential to improve type I allergy.

  7. Activated protein C inhibits neutrophil migration in allergic asthma: a randomised trial.

    PubMed

    de Boer, J Daan; Berger, Marieke; Majoor, Christof J; Kager, Liesbeth M; Meijers, Joost C M; Terpstra, Sanne; Nieuwland, Rienk; Boing, Anita N; Lutter, René; Wouters, Diana; van Mierlo, Gerard J; Zeerleder, Sacha S; Bel, Elisabeth H; van't Veer, Cornelis; de Vos, Alex F; van der Zee, Jaring S; van der Poll, Tom

    2015-12-01

    Asthma patients show evidence of a procoagulant state in their airways, accompanied by an impaired function of the anticoagulant protein C system. We aimed to study the effect of recombinant human activated protein C (rhAPC) in allergic asthma patients.We conducted a randomised, double-blind, placebo-controlled, proof-of-concept study in house dust mite (HDM) allergic asthma patients. Patients were randomised to receive intravenous rhAPC (24 µg·kg(-1)·h(-1); n=12) or placebo (n=12) for 11 h. 4 h after the start of infusion, a first bronchoscopy was performed to challenge one lung segment with saline (control) and a contralateral segment with a combination of HDM extract and lipopolysaccharide (HDM+LPS), thereby mimicking environmental house dust exposure. A second bronchoscopy was conducted 8 h after intrabronchial challenge to obtain bronchoalveolar lavage fluid (BALF).rhAPC did not influence HDM+LPS induced procoagulant changes in the lung. In contrast, rhAPC reduced BALF leukocyte counts by 43% relative to placebo, caused by an inhibitory effect on neutrophil influx (64% reduction), while leaving eosinophil influx unaltered. rhAPC also reduced neutrophil degranulation products in the airways.Intravenous rhAPC attenuates HDM+LPS-induced neutrophil migration and protein release in allergic asthma patients by an effect that does not rely on coagulation inhibition.

  8. Histamine H4-Receptors Inhibit Mast Cell Renin Release in Ischemia/Reperfusion via Protein Kinase Cε-Dependent Aldehyde Dehydrogenase Type-2 Activation

    PubMed Central

    Aldi, Silvia; Takano, Ken-ichi; Tomita, Kengo; Koda, Kenichiro; Chan, Noel Y.-K.; Marino, Alice; Salazar-Rodriguez, Mariselis; Thurmond, Robin L.

    2014-01-01

    Renin released by ischemia/reperfusion (I/R) from cardiac mast cells (MCs) activates a local renin-angiotensin system (RAS) causing arrhythmic dysfunction. Ischemic preconditioning (IPC) inhibits MC renin release and consequent activation of this local RAS. We postulated that MC histamine H4-receptors (H4Rs), being Gαi/o-coupled, might activate a protein kinase C isotype–ε (PKCε)–aldehyde dehydrogenase type-2 (ALDH2) cascade, ultimately eliminating MC-degranulating and renin-releasing effects of aldehydes formed in I/R and associated arrhythmias. We tested this hypothesis in ex vivo hearts, human mastocytoma cells, and bone marrow–derived MCs from wild-type and H4R knockout mice. We found that activation of MC H4Rs mimics the cardioprotective anti-RAS effects of IPC and that protection depends on the sequential activation of PKCε and ALDH2 in MCs, reducing aldehyde-induced MC degranulation and renin release and alleviating reperfusion arrhythmias. These cardioprotective effects are mimicked by selective H4R agonists and disappear when H4Rs are pharmacologically blocked or genetically deleted. Our results uncover a novel cardioprotective pathway in I/R, whereby activation of H4Rs on the MC membrane, possibly by MC-derived histamine, leads sequentially to PKCε and ALDH2 activation, reduction of toxic aldehyde-induced MC renin release, prevention of RAS activation, reduction of norepinephrine release, and ultimately to alleviation of reperfusion arrhythmias. This newly discovered protective pathway suggests that MC H4Rs may represent a new pharmacologic and therapeutic target for the direct alleviation of RAS-induced cardiac dysfunctions, including ischemic heart disease and congestive heart failure. PMID:24696042

  9. Extract from Aronia melanocarpa fruits potentiates the inhibition of platelet aggregation in the presence of endothelial cells

    PubMed Central

    Luzak, Boguslawa; Golanski, Jacek; Rozalski, Marek; Krajewska, Urszula; Olas, Beata

    2010-01-01

    Introduction Some polyphenolic compounds extracted from Aronia melanocarpa fruits (AM) have been reported to be cardioprotective agents. In this study we evaluated the ability of AM extract to increase the efficacy of human umbilical vein endothelial cells (HUVECs) to inhibit platelet functions in vitro. Material and methods This study encompasses two models of monitoring platelet reactivity: optical aggregation and platelet degranulation (monitored as the surface CD62P expression) in PRP upon the stimulation with ADP. Results We observed that only at low concentrations (5 µg/ml) did AM extract significantly improve antiplatelet action of HUVECs towards ADP-activated platelets in the aggregation test. Conclusions It is concluded that the potentiating effect of AM extract on the endothelial cell-mediated inhibition of platelet aggregation clearly depends on the used concentrations of Aronia-derived active compounds. Therefore, despite these encouraging preliminary outcomes on the beneficial effects of AM extract polyphenols, more profound dose-effect studies should certainly be considered before the implementation of Aronia-originating compounds in antiplatelet therapy and the prevention of cardiovascular diseases. PMID:22371737

  10. Saccadic Inhibition in Reading

    ERIC Educational Resources Information Center

    Reingold, Eyal M.; Stampe, Dave M.

    2004-01-01

    In 5 experiments, participants read text that was briefly replaced by a transient image for 33 ms at random intervals. A decrease in saccadic frequency, referred to as saccadic inhibition, occurred as early as 60-70 ms following the onset of abrupt changes in visual input. It was demonstrated that the saccadic inhibition was influenced by the…

  11. Resuscitation of traumatic hemorrhagic shock patients with hypertonic saline-without dextran-inhibits neutrophil and endothelial cell activation.

    PubMed

    Junger, Wolfgang G; Rhind, Shawn G; Rizoli, Sandro B; Cuschieri, Joseph; Shiu, Maria Y; Baker, Andrew J; Li, Linglin; Shek, Pang N; Hoyt, David B; Bulger, Eileen M

    2012-10-01

    Posttraumatic inflammation and excessive neutrophil activation cause multiple organ dysfunction syndrome (MODS), a major cause of death among hemorrhagic shock patients. Traditional resuscitation strategies may exacerbate inflammation; thus, novel fluid treatments are needed to reduce such posttraumatic complications. Hypertonic resuscitation fluids inhibit inflammation and reduce MODS in animal models. Here we studied the anti-inflammatory efficacy of hypertonic fluids in a controlled clinical trial. Trauma patients in hypovolemic shock were resuscitated in a prehospital setting with 250 mL of either 7.5% hypertonic saline (HS; n = 9), 7.5% hypertonic saline + 6% dextran 70 (HSD; n = 8), or 0.9% normal saline (NS; n = 17). Blood samples were collected on hospital admission and 12 and 24 h after resuscitation. Multicolor flow cytometry was used to quantify neutrophil expression of cell-surface activation/adhesion (CD11b, CD62L, CD64) and degranulation (CD63, CD66b, CD35) markers as well as oxidative burst activity. Circulating concentrations of soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVACM-1), P- and E-selectins, myeloperoxidase (MPO), and matrix metalloproteinase 9 (MMP-9) were assessed by immunoassay. Multiple organ dysfunction syndrome, leukocytosis, and mortality were lower in the HS and HSD groups than in the NS group. However, these differences were not statistically significant. Hypertonic saline prevented priming and activation and neutrophil oxidative burst and CD11b and CD66b expression. Hypertonic saline also reduced circulating markers of neutrophil degranulation (MPO and MMP-9) and endothelial cell activation (sICAM-1, sVCAM-1, soluble E-selectin, and soluble P-selectin). Hypertonic saline + 6% dextran 70 was less capable than HS of suppressing the upregulation of most of these activation markers. This study demonstrates that initial resuscitation with HS, but neither NS nor HSD, can attenuate

  12. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Carolyn

    1999-10-05

    This invention provides a system for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, this system can be used to palliate certain inflammatory and immunological conditions.

  13. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Caroline

    2001-10-09

    This invention provides compositions for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, these composition scan be used to palliate certain inflammatory and immunological conditions.

  14. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Caroline

    1999-01-01

    This invention provides compositions for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, these composition scan be used to palliate certain inflammatory and immunological conditions.

  15. Potentiation of latent inhibition.

    PubMed

    Rodriguez, Gabriel; Hall, Geoffrey

    2008-07-01

    Rats were given exposure either to an odor (almond) or a compound of odor plus taste (almond plus saline), prior to training in which the odor served as the conditioned stimulus. It was found, for both appetitive and aversive procedures, that conditioning was retarded by preexposure (a latent inhibition effect), and the extent of the retardation was greater in rats preexposed to the compound (i.e., latent inhibition to the odor was potentiated by the presence of the taste). In contrast, the presence of the taste during conditioning itself overshadowed learning about the odor. We argue that the presence of the salient taste in compound with the odor enhances the rate of associative learning, producing a rapid loss in the associability of the odor. This loss of associability will generate both overshadowing and the potentiation of latent inhibition that is observed after preexposure to the compound.

  16. Chitin deacetylase product inhibition.

    PubMed

    Jaworska, Malgorzata M

    2011-02-01

    Chitin deacetylase is the only known enzyme catalyzing the hydrolysis of the acetamino linkage in the N-acetylglucosamine units of chitin and chitosan. This reaction can play an important role in enzymatic production of chitosan from chitin, or in enzymatic modification of chitosan, which has applications in medicine, pharmacy or plant protection. It was previously shown that acetic acid, a product of the deacetylation process, may act as an inhibitor of chitin deacetylase. Here we show the mechanism of inhibition of chitin deacetylase isolated from Absidia orchidis vel coerulea by acetic acid released during the deacetylation process. The process follows competitive inhibition with respect to acetic acid with an inhibition constant of K(i) = 0.286 mmol/L. These results will help to find the optimal system to carry out the enzymatic deacetylation process for industrial applications.

  17. Dephosphorylation of the adaptor LAT and phospholipase C-γ by SHP-1 inhibits natural killer cell cytotoxicity.

    PubMed

    Matalon, Omri; Fried, Sophia; Ben-Shmuel, Aviad; Pauker, Maor H; Joseph, Noah; Keizer, Danielle; Piterburg, Marina; Barda-Saad, Mira

    2016-05-24

    Natural killer (NK) cells discriminate between healthy cells and virally infected or transformed self-cells by tuning activating and inhibitory signals received through cell surface receptors. Inhibitory receptors inhibit NK cell function by recruiting and activating the tyrosine phosphatase Src homology 2 (SH2) domain-containing protein tyrosine phosphatase-1 (SHP-1) to the plasma membrane. However, to date, the guanine nucleotide exchange factor VAV1 is the only direct SHP-1 substrate identified in NK cells. We reveal that the adaptor protein linker for activation of T cells (LAT) as well as phospholipase C-γ1 (PLC-γ1) and PLC-γ2 are SHP-1 substrates. Dephosphorylation of Tyr(132) in LAT by SHP-1 in NK cells abrogated the recruitment of PLC-γ1 and PLC-γ2 to the immunological synapse between the NK cell and a cancer cell target, which reduced NK cell degranulation and target cell killing. Furthermore, the ubiquitylation of LAT by the E3 ubiquitin ligases c-Cbl and Cbl-b, which was induced by LAT phosphorylation, led to the degradation of LAT in response to the engagement of inhibitory receptors on NK cells, which abrogated NK cell cytotoxicity. Knockdown of the Cbl proteins blocked LAT ubiquitylation, which promoted NK cell function. Expression of a ubiquitylation-resistant mutant LAT blocked inhibitory receptor signaling, enabling cells to become activated. Together, these data identify previously uncharacterized SHP-1 substrates and inhibitory mechanisms that determine the response of NK cells.

  18. PRT062607 Achieves Complete Inhibition of the Spleen Tyrosine Kinase at Tolerated Exposures Following Oral Dosing in Healthy Volunteers

    PubMed Central

    Rani, Aradhana; Betz, Andreas; Pak, Yvonne; Haberstock‐Debic, Helena; Pandey, Anjali; Hollenbach, Stanley; Gretler, Daniel D.; Mant, Tim; Jurcevic, Stipo; Sinha, Uma

    2016-01-01

    Abstract The spleen tyrosine kinase (SYK) regulates immune cell activation in response to engagement of a variety of receptors, making it an intriguing target for the treatment of inflammatory and autoimmune disorders as well as certain B‐cell malignancies. We have previously reported on the discovery and preclinical characterization of PRT062607, a potent and highly selective inhibitor of SYK that exhibits robust anti‐inflammatory activity in a variety of animal models. Here we present data from our first human studies aimed at characterizing the pharmacokinetics (PK), pharmacodynamics (PD), and safety of PRT062607 in healthy volunteers following single and multiple oral administrations. PRT062607 demonstrated a favorable PK profile and the ability to completely inhibit SYK activity in multiple whole‐blood assays. The PD half‐life in the more sensitive assays was approximately 24 hours and returned to predose levels by 72 hours. Selectivity for SYK was observed at all dose levels tested. Analysis of the PK/PD relationship indicated an IC50 of 324 nM for inhibition of B‐cell antigen receptor‐mediated B‐cell activation and 205 nM for inhibition of FcεRI‐mediated basophil degranulation. PRT062607 was safe and well tolerated across the entire range of doses. Clinical PK/PD was related to in vivo anti‐inflammatory activity of PRT062607 in the rat collagen‐induced arthritis model, which predicts that therapeutic concentrations may be safely achieved in humans for the treatment of autoimmune disease. PRT062607 has a desirable PK profile and is capable of safely, potently, and selectively suppressing SYK kinase function in humans following once‐daily oral dosing. PMID:27406873

  19. Peptide bioregulators inhibit apoptosis.

    PubMed

    Khavinson, V K; Kvetnoii, I M

    2000-12-01

    The effects of peptide bioregulators epithalon and vilon on the dynamics of irradiation-induced apoptotic death of spleen lymphocytes in rats indicate that these agents inhibit physiologically programmed cell death. The antiapoptotic effect of vilon was more pronounced, which corroborates the concept on tissue-specific effect of peptide bioregulators.

  20. Serine proteases inhibiting cyanopeptides.

    PubMed

    Radau, G

    2000-08-01

    There are many compounds inhibiting serine proteases which play an important role in the human organism. This article reviews publications on the low-molecular weight, serine protease inhibitory cyanopeptides and reports on new developments in establishing structure-activity relationships.

  1. Reinforcement of inhibition

    PubMed Central

    Anger, Douglas

    1983-01-01

    A differential-reinforcement-of-other-behavior (DRO) schedule with trials and delayed reinforcement was investigated. Periodically a wheel was briefly available to rats, followed six seconds later by brief availability of a bar. Variable-ratio food reinforcement of wheel turns was adjusted to give 95% turns. After variable-ratio-five reinforcement of bar presses produced 100% pressing, then separate ratio schedules were used for presses following turns (turn presses) and presses following nonturns (nonturn presses). Increasing nonturn-press reinforcements decreased turns, even though total reinforcements increased. Reversal by decreasing nonturn-press reinforcements raised turns, though with hysteresis. Thus food reinforcement increased nonturns even though delayed six to ten seconds after nonturns, a delay that greatly reduces response reinforcement. Those and other results indicate that the turn decrease was not due to reinforcement of competing responses. Evidence against other alternatives, and the reduction of responding by increased reinforcement, indicate that the term inhibition is appropriate for the phenomenon reinforced. Response-specific inhibition appears appropriate for this particular kind, since its effects are more specific to particular responses than Pavlovian conditioned-inhibition. Response-specific inhibition seems best considered a behavioral output comparable to responses (e.g., both reinforcible) but with important properties different from responses (e.g., different reinforcement-delay gradients). PMID:16812315

  2. Derivative of wheat germ agglutinin specifically inhibits formyl-peptide-induced polymorphonuclear leukocyte chemotaxis by blocking re-expression (or recycling) of receptors

    SciTech Connect

    Perez, H.D.; Elfman, F.; Lobo, E.; Sklar, L.; Chenoweth, D.; Hooper, C.

    1986-03-01

    The mechanism of action of a derivative of wheat germ agglutinin (WGA-D) which specifically and irreversibly inhibits N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced polymorphonuclear leukocyte (PMN) chemotaxis was examined. At a concentration that completely inhibited PMN chemotaxis, WGA-D had no effect on either the uptake or release of (/sup 3/H)-FMLP by PMN. Similarly, WGA-D did not affect either the short-term binding to, or internalization by, PMN of a fluoresceinated FMLP analog. WGA-D did interfere, however, with the re-expression (or recycling) of FMLP receptors by PMN that had been preincubated with 1 ..mu..M FMLP for 10 min at 4/sup 0/C. This effect was specific for WGA-D, because it was not observed when concanavalin A was used. Scatchard plot analysis of FMLP binding to PMN after receptor re-expression demonstrated that WGA-D-treated PMN had a significant diminution in the number of high affinity receptors. WGA-D-mediated inhibition of FMLP receptor re-expression was associated with inhibition of FMLP-induced PMN chemotaxis, but had no effect on either FMLP-induced PMN superoxide anion generation or degranulation. Studies using (/sup 12/%I)-WGA-D demonstrated that PMN did not internalize WGA-D spontaneously. The data indicate that WGA-D perhaps by binding to the FMLP receptor, inhibits FMLP-induced PMN chemotaxis by blocking the re-expression (or recycling) of a population of receptors required for continuous migration.

  3. Topical azithromycin and clarithromycin inhibit acute and chronic skin inflammation in sensitized mice, with apparent selectivity for Th2-mediated processes in delayed-type hypersensitivity.

    PubMed

    Ivetić Tkalčević, Vanesa; Cužić, Snježana; Kramarić, Miroslava Dominis; Parnham, Michael J; Eraković Haber, Vesna

    2012-02-01

    Macrolide antibiotics inhibit the secretion of Th1 cytokines while their effects on the release of Th2 cytokines are variable. We investigated molecular and cellular markers of Th1- and Th2-mediated inflammatory mechanisms and the anti-inflammatory activity of azithromycin and clarithromycin in phorbol 12-myristate 13-acetate (PMA) and oxazolone (OXA)-induced skin inflammation. Dexamethasone (50 μg/ear), azithromycin, and clarithromycin (500 μg/ear) reduced TNF-α and interleukin (IL)-1β concentration in ear tissue by inhibiting inflammatory cell accumulation in PMA-induced inflammation. In OXA-induced early delayed-type hypersensitivity (DTH), the macrolides (2 mg/ear) and dexamethasone (25 μg/ear) reduced ear tissue inflammatory cell infiltration and secretion of IL-4 while clarithromycin also decreased IFN-γ concentration. Macrolides showed better activity when administered after the challenge. In OXA-induced chronic DTH, azithromycin (1 mg/ear) reduced the number of ear tissue mast cells and decreased the concentration of IL-4 in ear tissue and of immunoglobulin (Ig)E in serum. Clarithromycin (1 mg/ear) reduced serum IgE concentration, possibly by a mechanism independent of IL-4, while both macrolides attenuated mast cell degranulation. In conclusion, azithromycin and clarithromycin attenuate pro-inflammatory cytokine production and leukocyte infiltration during innate immune reactions, while selectively affecting Th2 rather than Th1 immunity in DTH reactions.

  4. Immunization with Hypoallergens of Shrimp Allergen Tropomyosin Inhibits Shrimp Tropomyosin Specific IgE Reactivity

    PubMed Central

    Wai, Christine Y. Y.; Leung, Nicki Y. H.; Ho, Marco H. K.; Gershwin, Laurel J.; Shu, Shang An; Leung, Patrick S. C.; Chu, Ka Hou

    2014-01-01

    Designer proteins deprived of its IgE-binding reactivity are being sought as a regimen for allergen-specific immunotherapy. Although shrimp tropomyosin (Met e 1) has long been identified as the major shellfish allergen, no immunotherapy is currently available. In this study, we aim at identifying the Met e 1 IgE epitopes for construction of hypoallergens and to determine the IgE inhibitory capacity of the hypoallergens. IgE-binding epitopes were defined by three online computational models, ELISA and dot-blot using sera from shrimp allergy patients. Based on the epitope data, two hypoallergenic derivatives were constructed by site-directed mutagenesis (MEM49) and epitope deletion (MED171). Nine regions on Met e 1 were defined as the major IgE-binding epitopes. Both hypoallergens MEM49 and MED171 showed marked reduction in their in vitro reactivity towards IgE from shrimp allergy patients and Met e 1-sensitized mice, as well as considerable decrease in induction of mast cell degranulation as demonstrated in passive cutaneous anaphylaxis assay. Both hypoallergens were able to induce Met e 1-recognizing IgG antibodies in mice, specifically IgG2a antibodies, that strongly inhibited IgE from shrimp allergy subjects and Met e 1-sensitized mice from binding to Met e 1. These results indicate that the two designer hypoallergenic molecules MEM49 and MED171 exhibit desirable preclinical characteristics, including marked reduction in IgE reactivity and allergenicity, as well as ability to induce blocking IgG antibodies. This approach therefore offers promises for development of immunotherapeutic regimen for shrimp tropomyosin allergy. PMID:25365343

  5. Semantic processing and response inhibition.

    PubMed

    Chiang, Hsueh-Sheng; Motes, Michael A; Mudar, Raksha A; Rao, Neena K; Mansinghani, Sethesh; Brier, Matthew R; Maguire, Mandy J; Kraut, Michael A; Hart, John

    2013-11-13

    The present study examined functional MRI (fMRI) BOLD signal changes in response to object categorization during response selection and inhibition. Young adults (N=16) completed a Go/NoGo task with varying object categorization requirements while fMRI data were recorded. Response inhibition elicited increased signal change in various brain regions, including medial frontal areas, compared with response selection. BOLD signal in an area within the right angular gyrus was increased when higher-order categorization was mandated. In addition, signal change during response inhibition varied with categorization requirements in the left inferior temporal gyrus (lIT). lIT-mediated response inhibition when inhibiting the response only required lower-order categorization, but lIT mediated both response selection and inhibition when selecting and inhibiting the response required higher-order categorization. The findings characterized mechanisms mediating response inhibition associated with semantic object categorization in the 'what' visual object memory system.

  6. Dietary Compound Kaempferol Inhibits Airway Thickening Induced by Allergic Reaction in a Bovine Serum Albumin-Induced Model of Asthma.

    PubMed

    Shin, Daekeun; Park, Sin-Hye; Choi, Yean-Jung; Kim, Yun-Ho; Antika, Lucia Dwi; Habibah, Nurina Umy; Kang, Min-Kyung; Kang, Young-Hee

    2015-12-16

    Asthma is characterized by aberrant airways including epithelial thickening, goblet cell hyperplasia, and smooth muscle hypertrophy within the airway wall. The current study examined whether kaempferol inhibited mast cell degranulation and prostaglandin (PG) release leading to the development of aberrant airways, using an in vitro model of dinitrophenylated bovine serum albumin (DNP-BSA)-sensitized rat basophilic leukemia (RBL-2H3) mast cells and an in vivo model of BSA-challenged asthmatic mice. Nontoxic kaempferol at 10-20 μM suppressed β-hexosaminidase release and cyclooxygenase 2 (COX2)-mediated production of prostaglandin D2 (PGD2) and prostaglandin F2α (PGF2α) in sensitized mast cells. Oral administration of ≤20 mg/kg kaempferol blocked bovine serum albumin (BSA) inhalation-induced epithelial cell excrescence and smooth muscle hypertrophy by attenuating the induction of COX2 and the formation of PGD2 and PGF2α, together with reducing the anti-α-smooth muscle actin (α-SMA) expression in mouse airways. Kaempferol deterred the antigen-induced mast cell activation of cytosolic phospholipase A2 (cPLA2) responsive to protein kinase Cμ (PKCμ) and extracellular signal-regulated kinase (ERK). Furthermore, the antigen-challenged activation of Syk-phospholipase Cγ (PLCγ) pathway was dampened in kaempferol-supplemented mast cells. These results demonstrated that kaempferol inhibited airway wall thickening through disturbing Syk-PLCγ signaling and PKCμ-ERK-cPLA2-COX2 signaling in antigen-exposed mast cells. Thus, kaempferol may be a potent anti-allergic compound targeting allergic asthma typical of airway hyperplasia and hypertrophy.

  7. Pharmacological inhibition of FTO.

    PubMed

    McMurray, Fiona; Demetriades, Marina; Aik, WeiShen; Merkestein, Myrte; Kramer, Holger; Andrew, Daniel S; Scudamore, Cheryl L; Hough, Tertius A; Wells, Sara; Ashcroft, Frances M; McDonough, Michael A; Schofield, Christopher J; Cox, Roger D

    2015-01-01

    In 2007, a genome wide association study identified a SNP in intron one of the gene encoding human FTO that was associated with increased body mass index. Homozygous risk allele carriers are on average three kg heavier than those homozygous for the protective allele. FTO is a DNA/RNA demethylase, however, how this function affects body weight, if at all, is unknown. Here we aimed to pharmacologically inhibit FTO to examine the effect of its demethylase function in vitro and in vivo as a first step in evaluating the therapeutic potential of FTO. We showed that IOX3, a known inhibitor of the HIF prolyl hydroxylases, decreased protein expression of FTO (in C2C12 cells) and reduced maximal respiration rate in vitro. However, FTO protein levels were not significantly altered by treatment of mice with IOX3 at 60 mg/kg every two days. This treatment did not affect body weight, or RER, but did significantly reduce bone mineral density and content and alter adipose tissue distribution. Future compounds designed to selectively inhibit FTO's demethylase activity could be therapeutically useful for the treatment of obesity.

  8. Pharmacological Inhibition of FTO

    PubMed Central

    McMurray, Fiona; Demetriades, Marina; Aik, WeiShen; Merkestein, Myrte; Kramer, Holger; Andrew, Daniel S.; Scudamore, Cheryl L.; Hough, Tertius A.; Wells, Sara; Ashcroft, Frances M.; McDonough, Michael A.; Schofield, Christopher J.; Cox, Roger D.

    2015-01-01

    In 2007, a genome wide association study identified a SNP in intron one of the gene encoding human FTO that was associated with increased body mass index. Homozygous risk allele carriers are on average three kg heavier than those homozygous for the protective allele. FTO is a DNA/RNA demethylase, however, how this function affects body weight, if at all, is unknown. Here we aimed to pharmacologically inhibit FTO to examine the effect of its demethylase function in vitro and in vivo as a first step in evaluating the therapeutic potential of FTO. We showed that IOX3, a known inhibitor of the HIF prolyl hydroxylases, decreased protein expression of FTO (in C2C12 cells) and reduced maximal respiration rate in vitro. However, FTO protein levels were not significantly altered by treatment of mice with IOX3 at 60 mg/kg every two days. This treatment did not affect body weight, or RER, but did significantly reduce bone mineral density and content and alter adipose tissue distribution. Future compounds designed to selectively inhibit FTO’s demethylase activity could be therapeutically useful for the treatment of obesity. PMID:25830347

  9. 4-Chlorotetrazolo[1,5-a]quinoxaline inhibits activation of Syk kinase to suppress mast cells in vitro and mast cell-mediated passive cutaneous anaphylaxis in mice

    SciTech Connect

    Park, Kui Lea; Ko, Na Young; Lee, Jun Ho; Kim, Do Kyun; Kim, Hyuk Soon; Kim, A-Ram; Her, Erk; Kim, Bokyung; Kim, Hyung Sik; Moon, Eun-Yi; Kim, Young Mi; Kim, Hang-Rae; Choi, Wahn Soo

    2011-12-15

    4-Chlorotetrazolo[1,5-a]quinoxaline is a quinoxaline derivative. We aimed to study the effects of 4-chlorotetrazolo[1,5-a]quinoxaline on activation of mast cells in vitro and in mice. 4-Chlorotetrazolo[1,5-a]quinoxaline reversibly inhibited degranulation of mast cells in a dose-dependent manner, and also suppressed the expression and secretion of TNF-{alpha} and IL-4 in mast cells. Mechanistically, 4-chlorotetrazolo[1,5-a]quinoxaline inhibited activating phosphorylation of Syk and LAT, which are crucial for early Fc{epsilon}RI-mediated signaling events, as well as Akt and MAP kinases, which play essential roles in the production of various pro-inflammatory cytokines in mast cells. Notably, although 4-chlorotetrazolo[1,5-a]quinoxaline inhibited the activation of Fyn and Syk, minimal inhibition was observed in mast cells in the case of Lyn. Furthermore, consistent with its in vitro activity, 4-chlorotetrazolo[1,5-a]quinoxaline significantly suppressed mast cell-mediated passive cutaneous anaphylaxis in mice. In summary, the results from this study demonstrate that 4-chlorotetrazolo[1,5-a]quinoxaline shows an inhibitory effect on mast cells in vitro and in vivo, and that this is mediated by inhibiting the activation of Syk in mast cells. Therefore, 4-chlorotetrazolo[1,5-a]quinoxaline could be useful in the treatment of mast cell-mediated allergic diseases. -- Highlights: Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline is a quinoxaline derivative. Black-Right-Pointing-Pointer The effect of 4-chlorotetrazolo[1,5-a]quinoxaline on mast cells was investigated. Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline reversibly inhibited Syk activation. Black-Right-Pointing-Pointer 4-chlorotetrazolo[1,5-a]quinoxaline could be useful for IgE-mediated allergy.

  10. Psoralen and Ultraviolet A Light Treatment Directly Affects Phosphatidylinositol 3-Kinase Signal Transduction by Altering Plasma Membrane Packing.

    PubMed

    Van Aelst, Britt; Devloo, Rosalie; Zachée, Pierre; t'Kindt, Ruben; Sandra, Koen; Vandekerckhove, Philippe; Compernolle, Veerle; Feys, Hendrik B

    2016-11-18

    Psoralen and ultraviolet A light (PUVA) are used to kill pathogens in blood products and as a treatment of aberrant cell proliferation in dermatitis, cutaneous T-cell lymphoma, and graft-versus-host disease. DNA damage is well described, but the direct effects of PUVA on cell signal transduction are poorly understood. Because platelets are anucleate and contain archetypal signal transduction machinery, they are ideally suited to address this. Lipidomics on platelet membrane extracts showed that psoralen forms adducts with unsaturated carbon bonds of fatty acyls in all major phospholipid classes after PUVA. Such adducts increased lipid packing as measured by a blue shift of an environment-sensitive fluorescent probe in model liposomes. Furthermore, the interaction of these liposomes with lipid order-sensitive proteins like amphipathic lipid-packing sensor and α-synuclein was inhibited by PUVA. In platelets, PUVA caused poor membrane binding of Akt and Bruton's tyrosine kinase effectors following activation of the collagen glycoprotein VI and thrombin protease-activated receptor (PAR) 1. This resulted in defective Akt phosphorylation despite unaltered phosphatidylinositol 3,4,5-trisphosphate levels. Downstream integrin activation was furthermore affected similarly by PUVA following PAR1 (effective half-maximal concentration (EC50), 8.4 ± 1.1 versus 4.3 ± 1.1 μm) and glycoprotein VI (EC50, 1.61 ± 0.85 versus 0.26 ± 0.21 μg/ml) but not PAR4 (EC50, 50 ± 1 versus 58 ± 1 μm) signal transduction. Our findings were confirmed in T-cells from graft-versus-host disease patients treated with extracorporeal photopheresis, a form of systemic PUVA. In conclusion, PUVA increases the order of lipid phases by covalent modification of phospholipids, thereby inhibiting membrane recruitment of effector kinases.

  11. Firefly luciferase inhibition.

    PubMed

    Leitão, João M M; Esteves da Silva, Joaquim C G

    2010-10-05

    Firefly luciferase (Luc) is the most studied of the luciferase enzymes and the mechanism and kinetics of the reactions catalyzed by this enzyme have been relatively well characterized. Luc catalyzes the bioluminescent reaction involving firefly luciferin (D-LH(2)), adenosine triphosphate (ATP), magnesium ion and molecular oxygen with the formation of an electronically excited species (oxyluciferin), inorganic pyrophosphate (PPi), carbon dioxide and adenosine monophosphate (AMP). Luc also catalyzes other non-luminescent reactions, which can interfere with the light production mechanism. Following electronic relaxation, the excited oxyluciferin emits radiation in the visible region of the electromagnetic spectrum (550-570 nm). Among the various possible compounds, several classes of inhibitory substances interfere with the activity of this enzyme: here, we consider substrate-related compounds, intermediates or products of the Luc catalyzed reactions, in addition to anesthetics and, fatty acids. This review summarizes the main inhibitors of Luc and the corresponding inhibition kinetic parameters.

  12. Anxiety and retrieval inhibition: support for an enhanced inhibition account.

    PubMed

    Nuñez, Mia; Gregory, Josh; Zinbarg, Richard E

    2017-02-01

    Retrieval inhibition of negative associations is important for exposure therapy for anxiety, but the relationship between memory inhibition and anxiety is not well understood-anxiety could either be associated with enhanced or deficient inhibition. The present study tested these two competing hypotheses by measuring retrieval inhibition of negative stimuli by related neutral stimuli. Non-clinically anxious undergraduates completed measures of trait and state anxiety and completed a retrieval induced forgetting task. Adaptive forgetting varied with state anxiety. Low levels of state anxiety were associated with no evidence for retrieval inhibition for either threatening or non-threatening categories. Participants in the middle tertile of state anxiety scores exhibited retrieval inhibition for non-threatening categories but not for threatening categories. Participants in the highest tertile of state anxiety, however, exhibited retrieval inhibition for both threatening and non-threatening categories with the magnitude of retrieval inhibition being greater for threatening than non-threatening categories. The data are in line with the avoidance aspect of the vigilance-avoidance theory of anxiety and inhibition. Implications for cognitive behavioural therapy practices are discussed.

  13. Simultaneous determination of histamine and prostaglandin D2 using an LC-ESI-MS/MS method with positive/negative ion-switching ionization modes: application to the study of anti-allergic flavonoids on the degranulation of KU812 cells.

    PubMed

    Koyama, Junko; Taga, Shiori; Shimizu, Kae; Shimizu, Maki; Morita, Izumi; Takeuchi, Atsuko

    2011-09-01

    A new method for simultaneous determination of histamine and prostaglandin D(2) (PGD(2)) by liquid chromatography-electrospray ionization tandem mass spectrometry operated in positive and negative ionization switching modes was developed and validated without a previous derivatization step. This method was used to measure histamine and PGD(2) release following degranulation of KU812 human basophilic cells, using pyrazol and d(4)-PGD(2) as internal standards. Analyses were performed on a liquid chromatography system employing a Cosmosil 5C(18) PAQ column and an isocratic elution with mixed solution of methanol-water (7:3, v/v) with 0.0015% trifluoroacetic acid at a flow rate of 0.2 mL/min. A triple-quadrupole mass spectrometer operating in selected reaction monitoring mode simultaneously monitored using the following transitions: positive m/z 112/95 for histamine and negative m/z 351/271 for PGD(2). The retention times of histamine and pyrazol were 4.2 and 5.0 min, respectively. PGD(2) and d(4)-PGD(2) had retention times of 8.5 min. The limits of detection were 0.3 and 0.5 ng/mL for histamine and PGD(2), respectively. The relative standard deviations of the retention time and peak area for histamine were between 1.6% and 7.7%, and were 1.2% and 7.8% for PGD(2). This method was used to evaluate the anti-allergic effects of 26 flavonoids and sodium cromoglicate which are first-line anti-allergic drugs. Of these compounds, baicalein and morin were the most potent inhibitors.

  14. Ethanol Inhibits High-Affinity Immunoglobulin E Receptor (FcεRI) Signaling in Mast Cells by Suppressing the Function of FcεRI-Cholesterol Signalosome.

    PubMed

    Draberova, Lubica; Paulenda, Tomas; Halova, Ivana; Potuckova, Lucie; Bugajev, Viktor; Bambouskova, Monika; Tumova, Magda; Draber, Petr

    2015-01-01

    Ethanol has multiple effects on biochemical events in a variety of cell types, including the high-affinity immunoglobulin E receptor (FcεRI) signaling in antigen-activated mast cells. However, the underlying molecular mechanism remains unknown. To get better understanding of the effect of ethanol on FcεRI-mediated signaling we examined the effect of short-term treatment with non-toxic concentrations of ethanol on FcεRI signaling events in mouse bone marrow-derived mast cells. We found that 15 min exposure to ethanol inhibited antigen-induced degranulation, calcium mobilization, expression of proinflammatory cytokine genes (tumor necrosis factor-α, interleukin-6, and interleukin-13), and formation of reactive oxygen species in a dose-dependent manner. Removal of cellular cholesterol with methyl-β-cyclodextrin had a similar effect and potentiated some of the inhibitory effects of ethanol. In contrast, exposure of the cells to cholesterol-saturated methyl-β-cyclodextrin abolished in part the inhibitory effect of ethanol on calcium response and production of reactive oxygen species, supporting lipid-centric theories of ethanol action on the earliest stages of mast cell signaling. Further studies showed that exposure to ethanol and/or removal of cholesterol inhibited early FcεRI activation events, including tyrosine phosphorylation of the FcεRI β and γ subunits, SYK kinases, LAT adaptor protein, phospholipase Cγ, STAT5, and AKT and internalization of aggregated FcεRI. Interestingly, ethanol alone, and particularly in combination with methyl-β-cyclodextrin, enhanced phosphorylation of negative regulatory tyrosine 507 of LYN kinase. Finally, we found that ethanol reduced passive cutaneous anaphylactic reaction in mice, suggesting that ethanol also inhibits FcεRI signaling under in vivo conditions. The combined data indicate that ethanol interferes with early antigen-induced signaling events in mast cells by suppressing the function of Fc

  15. Ethanol Inhibits High-Affinity Immunoglobulin E Receptor (FcεRI) Signaling in Mast Cells by Suppressing the Function of FcεRI-Cholesterol Signalosome

    PubMed Central

    Draberova, Lubica; Paulenda, Tomas; Halova, Ivana; Potuckova, Lucie; Bugajev, Viktor; Bambouskova, Monika; Tumova, Magda; Draber, Petr

    2015-01-01

    Ethanol has multiple effects on biochemical events in a variety of cell types, including the high-affinity immunoglobulin E receptor (FcεRI) signaling in antigen-activated mast cells. However, the underlying molecular mechanism remains unknown. To get better understanding of the effect of ethanol on FcεRI-mediated signaling we examined the effect of short-term treatment with non-toxic concentrations of ethanol on FcεRI signaling events in mouse bone marrow-derived mast cells. We found that 15 min exposure to ethanol inhibited antigen-induced degranulation, calcium mobilization, expression of proinflammatory cytokine genes (tumor necrosis factor-α, interleukin-6, and interleukin-13), and formation of reactive oxygen species in a dose-dependent manner. Removal of cellular cholesterol with methyl-β-cyclodextrin had a similar effect and potentiated some of the inhibitory effects of ethanol. In contrast, exposure of the cells to cholesterol-saturated methyl-β-cyclodextrin abolished in part the inhibitory effect of ethanol on calcium response and production of reactive oxygen species, supporting lipid-centric theories of ethanol action on the earliest stages of mast cell signaling. Further studies showed that exposure to ethanol and/or removal of cholesterol inhibited early FcεRI activation events, including tyrosine phosphorylation of the FcεRI β and γ subunits, SYK kinases, LAT adaptor protein, phospholipase Cγ, STAT5, and AKT and internalization of aggregated FcεRI. Interestingly, ethanol alone, and particularly in combination with methyl-β-cyclodextrin, enhanced phosphorylation of negative regulatory tyrosine 507 of LYN kinase. Finally, we found that ethanol reduced passive cutaneous anaphylactic reaction in mice, suggesting that ethanol also inhibits FcεRI signaling under in vivo conditions. The combined data indicate that ethanol interferes with early antigen-induced signaling events in mast cells by suppressing the function of Fc

  16. A soluble fragment of the tumor antigen BCL2-associated athanogene 6 (BAG-6) is essential and sufficient for inhibition of NKp30 receptor-dependent cytotoxicity of natural killer cells.

    PubMed

    Binici, Janina; Hartmann, Jessica; Herrmann, Julia; Schreiber, Christine; Beyer, Steffen; Güler, Günnur; Vogel, Vitali; Tumulka, Franz; Abele, Rupert; Mäntele, Werner; Koch, Joachim

    2013-11-29

    Immunosurveillance of tumor cells depends on NKp30, a major activating receptor of human natural killer (NK) cells. The human BCL2-associated athanogene 6 (BAG-6, also known as BAT3; 1126 amino acids) is a cellular ligand of NKp30. To date, little is known about the molecular details of this receptor ligand system. Within the current study, we have located the binding site of NKp30 to a sequence stretch of 250 amino acids in the C-terminal region of BAG-6 (BAG-6(686-936)). BAG-6(686-936) forms a noncovalent dimer of 57-59 kDa, which is sufficient for high affinity interaction with NKp30 (KD < 100 nM). As our most important finding, BAG-6(686-936) inhibits NKp30-dependent signaling, interferon-γ release, and degranulation of NK cells in the presence of malignantly transformed target cells. Based on these data, we show for the first time that BAG-6(686-936) comprises a subdomain of BAG-6, which is sufficient for receptor docking and inhibition of NKp30-dependent NK cell cytotoxicity as part of a tumor immune escape mechanism. These molecular insights provide an access point to restore tumor immunosurveillance by NK cells and to increase the efficacy of cellular therapies.

  17. Inhibition of cellulases by phenols

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The inhibition of enzymes by the end products that they make is a well-known phenomenon. Another form of inhibition is manifested by the decrease in hydrolysis of pretreated cellulosic material as the concentration of solid biomass material increases, even though the ratio of enzyme to cellulose is...

  18. Can Arousal Modulate Response Inhibition?

    ERIC Educational Resources Information Center

    Weinbach, Noam; Kalanthroff, Eyal; Avnit, Amir; Henik, Avishai

    2015-01-01

    The goal of the present study was to examine if and how arousal can modulate response inhibition. Two competing hypotheses can be drawn from previous literature. One holds that alerting cues that elevate arousal should result in an impulsive response and therefore impair response inhibition. The other suggests that alerting enhances processing of…

  19. Forcing contact inhibition of locomotion.

    PubMed

    Roycroft, Alice; Mayor, Roberto

    2015-07-01

    Contact inhibition of locomotion drives a variety of biological phenomenon, from cell dispersion to collective cell migration and cancer invasion. New imaging techniques have allowed contact inhibition of locomotion to be visualised in vivo for the first time, helping to elucidate some of the molecules and forces involved in this phenomenon.

  20. Balanced feedforward inhibition and dominant recurrent inhibition in olfactory cortex

    PubMed Central

    Large, Adam M.; Vogler, Nathan W.; Mielo, Samantha; Oswald, Anne-Marie M.

    2016-01-01

    Throughout the brain, the recruitment of feedforward and recurrent inhibition shapes neural responses. However, disentangling the relative contributions of these often-overlapping cortical circuits is challenging. The piriform cortex provides an ideal system to address this issue because the interneurons responsible for feedforward and recurrent inhibition are anatomically segregated in layer (L) 1 and L2/3 respectively. Here we use a combination of optical and electrical activation of interneurons to profile the inhibitory input received by three classes of principal excitatory neuron in the anterior piriform cortex. In all classes, we find that L1 interneurons provide weaker inhibition than L2/3 interneurons. Nonetheless, feedforward inhibitory strength covaries with the amount of afferent excitation received by each class of principal neuron. In contrast, intracortical stimulation of L2/3 evokes strong inhibition that dominates recurrent excitation in all classes. Finally, we find that the relative contributions of feedforward and recurrent pathways differ between principal neuron classes. Specifically, L2 neurons receive more reliable afferent drive and less overall inhibition than L3 neurons. Alternatively, L3 neurons receive substantially more intracortical inhibition. These three features—balanced afferent drive, dominant recurrent inhibition, and differential recruitment by afferent vs. intracortical circuits, dependent on cell class—suggest mechanisms for olfactory processing that may extend to other sensory cortices. PMID:26858458

  1. Biology of TACE inhibition

    PubMed Central

    Newton, R; Solomon, K; Covington, M; Decicco, C; Haley, P; Friedman, S; Vaddi, K

    2001-01-01

    Studies conducted over the past decade have demonstrated a central role for tumour necrosis factor α (TNFα) in inflammatory diseases. As a result of this work, a number of biological agents that neutralise the activity of this cytokine have entered the clinic. The recent clinical data obtained with etanercept and infliximab highlight the relevance of this strategy. TNFα converting enzyme (TACE) is the metalloproteinase that processes the 26 kDa membrane bound precursor of TNFα (proTNFα) to the 17 kDa soluble component. Although a number of proteases have been shown to process proTNFα, none do so with the efficiency of TACE. A series of orally bioavailable, selective, and potent TACE inhibitors are currently in clinical development. These inhibitors effectively block TACE mediated processing of proTNFα and can reduce TNF production by lipopolysaccharide stimulated whole blood by >95%. Through a series of studies it is shown here that >80% of the unprocessed proTNFα is degraded intracellularly. The remainder appears to be transiently expressed on the cell surface. Although, in vitro, TACE inhibition has also been implicated in shedding of p55 and p75 surface TNFα receptors, the in vivo data cast doubt on the consequences of this finding. In a mouse model of collagen-induced arthritis, the inhibitors are efficacious both prophylactically and therapeutically. The efficacy seen is equivalent to strategies that neutralise TNFα. In many studies greater efficacy is observed with the TACE inhibitors, presumably owing to greater penetration to the site of TNFα production.

 PMID:11890648

  2. Novel Antiplatelet Activity of Minocycline Involves Inhibition of MLK3-p38 Mitogen Activated Protein Kinase Axis

    PubMed Central

    Jackson, Joseph W.; Singh, Meera V.; Singh, Vir B.; Jones, Letitia D.; Davidson, Gregory A.; Ture, Sara; Morrell, Craig N.; Schifitto, Giovanni; Maggirwar, Sanjay B.

    2016-01-01

    Platelets play an essential role in hemostasis and wound healing by facilitating thrombus formation at sites of injury. Platelets also mediate inflammation and contain several pro-inflammatory molecules including cytokines and chemokines that mediate leukocyte recruitment and activation. Not surprisingly, platelet dysfunction is known to contribute to several inflammatory disorders. Antiplatelet therapies, such as aspirin, adenosine diphosphate (ADP) antagonists, glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors, and anticoagulants such as warfarin, dampen platelet activity at the risk of unwarranted bleeding. Thus, the development of drugs that reduce platelet-mediated inflammation without interfering with thrombus formation is of importance to combat platelet-associated disorders. We have shown here for the first time that the tetracycline antibiotic, minocycline, administered to HIV-infected individuals reduces plasma levels of soluble CD40L and platelet factor 4 levels, host molecules predominately released by platelets. Minocycline reduced the activation of isolated platelets in the presence of the potent platelet activator, thrombin, as measured by ELISA and flow cytometry. Platelet degranulation was reduced upon exposure to minocycline as shown by mepacrine retention and flow cytometry. However, minocycline had no effect on spreading, aggregation, GPIIb/IIIa activation, or in vivo thrombus formation. Lastly, immunoblot analysis suggests that the antiplatelet activity of minocycline is likely mediated by inhibition of mixed lineage kinase 3 (MLK3)-p38 MAPK signaling axis and loss of p38 activity. Our findings provide a better understanding of platelet biology and a novel repurposing of an established antibiotic, minocycline, to specifically reduce platelet granule release without affecting thrombosis, which may yield insights in generating novel, specific antiplatelet therapies. PMID:27270236

  3. Catalase is inhibited by flavonoids.

    PubMed

    Krych, Justyna; Gebicka, Lidia

    2013-07-01

    Catalases, heme enzymes, which catalyze decomposition of hydrogen peroxide to water and molecular oxygen, belong to the antioxidant defense system of the cell. In this work we have shown that catalase from bovine liver is inhibited by flavonoids. The inhibition is, at least partially, due to the formation of hydrogen bonds between catalase and flavonoids. In the presence of some flavonoids the formation of unreactive catalase compound II has been detected. The most potent catalase inhibitors among the tested flavonoids have appeared myricetin, epicatechin gallate and epigallocatechin gallate. The relationship between the degree of enzyme inhibition and molecular structure of flavonoids has been analyzed.

  4. Infrared inhibition of embryonic hearts

    NASA Astrophysics Data System (ADS)

    Wang, Yves T.; Rollins, Andrew M.; Jenkins, Michael W.

    2016-06-01

    Infrared control is a new technique that uses pulsed infrared lasers to thermally alter electrical activity. Originally developed for nerves, we have applied this technology to embryonic hearts using a quail model, previously demonstrating infrared stimulation and, here, infrared inhibition. Infrared inhibition enables repeatable and reversible block, stopping cardiac contractions for several seconds. Normal beating resumes after the laser is turned off. The block can be spatially specific, affecting propagation on the ventricle or initiation on the atrium. Optical mapping showed that the block affects action potentials and not just calcium or contraction. Increased resting intracellular calcium was observed after a 30-s exposure to the inhibition laser, which likely resulted in reduced mechanical function. Further optimization of the laser illumination should reduce potential damage. Stopping cardiac contractions by disrupting electrical activity with infrared inhibition has the potential to be a powerful tool for studying the developing heart.

  5. Phosphanilic Acid Inhibits Dihydropteroate Synthase

    DTIC Science & Technology

    1989-11-01

    dihydropteroate synthases of P. aeruginosa and E . coli were about equally susceptible to inhibition by PA. These results suggest that cells of P. aeruginosa...are more permeable to PA than cells of E . coli . Although a weak inhibitor, PA acted on dihydropteroate synthase in the same manner as the sulfonamides...with which PA is structurally related. Inhibition of E . coli by PA in a basal salts-glucose medium was prevented by p-aminobenzoic acid (pABA). However

  6. Inhibition of MMPs by alcohols

    PubMed Central

    Tezvergil-Mutluay, Arzu; Agee, Kelli A.; Hoshika, Tomohiro; Uchiyama, Toshikazu; Tjäderhane, Leo; Breschi, Lorenzo; Mazzoni, Annalisa; Thompson, Jeremy M.; McCracken, Courtney E.; Looney, Stephen W.; Tay, Franklin R.; Pashley, David H.

    2011-01-01

    Objectives While screening the activity of potential inhibitors of matrix metalloproteinases (MMPs), due to the limited water solubility of some of the compounds, they had to be solubilized in ethanol. When ethanol solvent controls were run, they were found to partially inhibit MMPs. Thus, the purpose of this study was to compare the MMP-inhibitory activity of a series of alcohols. Methods The possible inhibitory activity of a series of alcohols was measured against soluble rhMMP-9 and insoluble matrix-bound endogenous MMPs of dentin in completely demineralized dentin. Increasing concentrations (0.17, 0.86, 1.71 and 4.28 moles/L) of a homologous series of alcohols (i.e. methanol, ethanol, propanols, butanols, pentanols, hexanols, the ethanol ester of methacrylic acid, heptanols and octanol) were compared to ethanediol, and propanediol by regression analysis to calculate the molar concentration required to inhibit MMPs by 50% (i.e. the IC50). Results Using two different MMP models, alcohols were shown to inhibit rhMMP-9 and the endogenous proteases of dentin matrix in a dose-dependent manner. The degree of MMP inhibition by alcohols increased with chain length up to 4 methylene groups. Based on the molar concentration required to inhibit rhMMP-9 fifty percent, 2-hydroxyethylmethacrylate (HEMA), 3-hexanol, 3-heptanol and 1-octanol gave the strongest inhibition. Significance The results indicate that alcohols with 4 methylene groups inhibit MMPs more effectively than methanol or ethanol. MMP inhibition was inversely related to the Hoy's solubility parameter for hydrogen bonding forces of the alcohols (i.e. to their hydrophilicity). PMID:21676453

  7. Tim-3 Is Upregulated in NK Cells during Early Pregnancy and Inhibits NK Cytotoxicity toward Trophoblast in Galectin-9 Dependent Pathway

    PubMed Central

    Sun, Jintang; Yang, Meixiang; Ban, Yanli; Gao, Wenjuan; Song, Bingfeng; Wang, Yang; Zhang, Yun; Shao, Qianqian; Kong, Beihua; Qu, Xun

    2016-01-01

    NK cells accumulate at the maternal-fetal interface (MFI) and play essential roles in maintaining immune tolerance during pregnancy. The mechanisms that facilitate NK cells tolerance to fetal tissue are largely unknown. T cell Ig and mucin domain-containing protein 3 (Tim-3) is a newly defined molecule with essential immunological function in many physiological and pathological processes. Recent study showed that Tim-3 was involved in the regulation of immune tolerance at MFI. However, whether Tim-3 regulates NK cells cytotoxicity toward trophoblasts is unclear. Here, we showed Tim-3 was mainly expressed by decidual NK cells (dNK) and Tim-3 level in dNK was higher than peripheral NK cells (pNK). Tim-3+ dNK expressed more levels of mature markers CD94 and CD69 than Tim-3- dNK cells and blocking Tim-3 significantly inhibited dNK IFN-γ and TNF-α secretion. Furthermore, we found TGF-β1 may contribute to such up-regulation of Tim-3 in NK cells. Interestingly, blocking Tim-3 enhanced NK cytotoxicity toward trophoblast cell line HTR-8 but not K562. We found HTR-8 expressed Tim-3 ligand Galectin-9, in contrast K562 did not. Small interfering RNA-mediated silencing of Galectin-9 expression enhanced NK cytotoxicity toward HTR-8. We further showed Tim-3/Galecin-9 inhibited NK cytotoxicity toward trophoblast partially via impairing the degranulation process. In addition, clinical data showed that abnormal Tim-3 level on pNK might be associated with recurrent spontaneous abortion (RSA). Thus, our data demonstrate Tim-3/Galectin-9 pathway maintains local tolerance by suppressing NK cytotoxicity toward trophoblasts which may represent a new immunologic tolerance mechanism at MFI. PMID:26789128

  8. Tim-3 Is Upregulated in NK Cells during Early Pregnancy and Inhibits NK Cytotoxicity toward Trophoblast in Galectin-9 Dependent Pathway.

    PubMed

    Sun, Jintang; Yang, Meixiang; Ban, Yanli; Gao, Wenjuan; Song, Bingfeng; Wang, Yang; Zhang, Yun; Shao, Qianqian; Kong, Beihua; Qu, Xun

    2016-01-01

    NK cells accumulate at the maternal-fetal interface (MFI) and play essential roles in maintaining immune tolerance during pregnancy. The mechanisms that facilitate NK cells tolerance to fetal tissue are largely unknown. T cell Ig and mucin domain-containing protein 3 (Tim-3) is a newly defined molecule with essential immunological function in many physiological and pathological processes. Recent study showed that Tim-3 was involved in the regulation of immune tolerance at MFI. However, whether Tim-3 regulates NK cells cytotoxicity toward trophoblasts is unclear. Here, we showed Tim-3 was mainly expressed by decidual NK cells (dNK) and Tim-3 level in dNK was higher than peripheral NK cells (pNK). Tim-3(+) dNK expressed more levels of mature markers CD94 and CD69 than Tim-3- dNK cells and blocking Tim-3 significantly inhibited dNK IFN-γ and TNF-α secretion. Furthermore, we found TGF-β1 may contribute to such up-regulation of Tim-3 in NK cells. Interestingly, blocking Tim-3 enhanced NK cytotoxicity toward trophoblast cell line HTR-8 but not K562. We found HTR-8 expressed Tim-3 ligand Galectin-9, in contrast K562 did not. Small interfering RNA-mediated silencing of Galectin-9 expression enhanced NK cytotoxicity toward HTR-8. We further showed Tim-3/Galecin-9 inhibited NK cytotoxicity toward trophoblast partially via impairing the degranulation process. In addition, clinical data showed that abnormal Tim-3 level on pNK might be associated with recurrent spontaneous abortion (RSA). Thus, our data demonstrate Tim-3/Galectin-9 pathway maintains local tolerance by suppressing NK cytotoxicity toward trophoblasts which may represent a new immunologic tolerance mechanism at MFI.

  9. Chorein sensitivity of cytoskeletal organization and degranulation of platelets.

    PubMed

    Schmidt, Eva-Maria; Schmid, Evi; Münzer, Patrick; Hermann, Andreas; Eyrich, Ann-Kathrin; Russo, Antonella; Walker, Britta; Gu, Shuchen; vom Hagen, Jennifer Müller; Faggio, Caterina; Schaller, Martin; Föller, Michael; Schöls, Ludger; Gawaz, Meinrad; Borst, Oliver; Storch, Alexander; Stournaras, Christos; Lang, Florian

    2013-07-01

    Chorea-acanthocytosis (ChAc), a lethal disease caused by defective chorein, is characterized by neurodegeneration and erythrocyte acanthocytosis. The functional significance of chorein in other cell types remained ill-defined. The present study revealed chorein expression in blood platelets. As compared to platelets from healthy volunteers, platelets from patients with ChAc displayed a 47% increased globular/filamentous actin ratio, indicating actin depolymerization. Moreover, phosphoinositide-3-kinase subunit p85 phosphorylation, p21 protein-activated kinase (PAK1) phosphorylation, as well as vesicle-associated membrane protein 8 (VAMP8) expression were significantly reduced in platelets from patients with ChAc (by 17, 22, and 39%, respectively) and in megakaryocytic (MEG-01) cells following chorein silencing (by 16, 54, and 11%, respectively). Activation-induced platelet secretion from dense granules (ATP release) and α granules (P-selectin exposure) were significantly less (by 55% after stimulation with 1 μg/ml CRP and by 33% after stimulation with 5 μM TRAP, respectively) in ChAc platelets than in control platelets. Furthermore, platelet aggregation following stimulation with different platelet agonists was significantly impaired. These observations reveal a completely novel function of chorein, i.e., regulation of secretion and aggregation of blood platelets.

  10. Inhibition of Hageman factor activation

    PubMed Central

    Nossel, H. L.; Rubin, H.; Drillings, M.; Hsieh, R.

    1968-01-01

    A method for studying inhibitors of the contact stages of blood coagulation is described. A number of positively charged substances were shown to inhibit the contact stages. The inhibitory substances include spermine, cytochrome c, ribonuclease, and lysozyme. The inhibitory effect of these substances was neutralized by the addition of an activated plasma thromboplastin antecedent, factor XI, (PTA) fraction. Other positively charged substances including protamine, hexadimethrine, polylysine, polyornithine, methylene blue, and ortho-toluidine blue also inhibited the contact stages of coagulation, but the inhibitory effect on coagulation was not neutralized by the activated PTA fraction. Negatively charged substances such as heparin and insulin did not inhibit the contact stages of coagulation. Cytochrome c inhibited Celite adsorption of a partially purified Hageman factor fraction, and cytochrome, ribonuclease, spermine, and lysozome inhibited the adsorption of Hageman factor from PTA-deficient plasma. Very much smaller quantities of Celite completely adsorbed Hageman factor from the fraction rather than from whole plasma, which suggested the possibility that plasma contains an inhibitor or inhibitors of Hageman factor adsorption. Furthermore cytochrome c, spermine, ribonuclease, and lysozyme inhibited the coagulant activity of the following activators of the Hageman and PTA factors: Celite, kaolin, sodium stearate, ellagic acid, and skin. It is suggested that negatively charged sites on these activators are critical for adsorption and activation and that inhibition results from neutralization of the negatively charged sites by the adsorbed inhibtor. Tests with polylysine polymers indicate that inhibitory activity is directly related to molecular size over the molecular weight range of 4000 to 100,000. PMID:5645860

  11. Photo-activated psoralen binds the ErbB2 catalytic kinase domain, blocking ErbB2 signaling and triggering tumor cell apoptosis.

    PubMed

    Xia, Wenle; Gooden, David; Liu, Leihua; Zhao, Sumin; Soderblom, Erik J; Toone, Eric J; Beyer, Wayne F; Walder, Harold; Spector, Neil L

    2014-01-01

    Photo-activation of psoralen with UVA irradiation, referred to as PUVA, is used in the treatment of proliferative skin disorders. The anti-proliferative effects of PUVA have been largely attributed to psoralen intercalation of DNA, which upon UV treatment, triggers the formation of interstrand DNA crosslinks (ICL) that inhibit transcription and DNA replication. Here, we show that PUVA exerts antitumor effects in models of human breast cancer that overexpress the ErbB2 receptor tyrosine kinase oncogene, through a new mechanism. Independent of ICL formation, the antitumor effects of PUVA in ErbB2+ breast cancer models can instead be mediated through inhibition of ErbB2 activation and signaling. Using a mass spectroscopy-based approach, we show for the first time that photo-activated 8MOP (8-methoxypsoralen) interacts with the ErbB2 catalytic autokinase domain. Furthermore, PUVA can reverse therapeutic resistance to lapatinib and other ErbB2 targeted therapies, including resistance mediated via expression of a phosphorylated, truncated form of ErbB2 (p85(ErbB2)) that is preferentially expressed in tumor cell nuclei. Current ErbB2 targeted therapies, small molecule kinase inhibitors or antibodies, do not block the phosphorylated, activated state of p85(ErbB2). Here we show that PUVA reduced p85(ErbB2) phosphorylation leading to tumor cell apoptosis. Thus, in addition to its effects on DNA and the formation of ICL, PUVA represents a novel ErbB2 targeted therapy for the treatment of ErbB2+ breast cancers, including those that have developed resistance to other ErbB2 targeted therapies.

  12. Lateral Inhibition during Nociceptive Processing.

    PubMed

    Quevedo, Alexandre S; Mørch, Carsten Dahl; Andersen, Ole K; Coghill, Robert C

    2017-02-11

    Spatial summation of pain is the increase of perceived intensity that occurs as the stimulated area increases. Spatial summation of pain is sub-additive in that increasing the stimulus area produces a disproportionately small increase in the perceived intensity of pain. A possible explanation for sub-additive summation may be that convergent excitatory information is modulated by lateral inhibition. To test the hypothesis that lateral inhibition may limit spatial summation of pain, we delivered different patterns of noxious thermal stimuli to the abdomens of 15 subjects using a computer-controlled CO2-laser. Lines (5mm wide) of variable lengths (4cm, 8cm) were compared to two-point stimuli delivered at the same position/separation as the length of lines. When compared to one-point control stimuli, two-point stimulus patterns produced statistically significant spatial summation of pain, while no such summation was detected during line stimulus patterns. Direct comparison of pain intensity evoked by two-point pattern stimuli with line pattern stimuli revealed that two-point patterns were perceived as significantly more painful, despite the fact that the two-point pattern stimulated far smaller areas of skin. Thus, the stimulation of the skin region between the endpoints of the lines appears to produce inhibition. These findings indicate that lateral inhibition limits spatial summation of pain and is an intrinsic component of nociceptive information processing. Disruption of such lateral inhibition may contribute substantially to the radiation of some types of chronic pain.

  13. Inhibition of phospholipase D activation by CYL-26z in formyl peptide-stimulated neutrophils involves the blockade of RhoA activation.

    PubMed

    Kuan, Yu-Hsiang; Lin, Ruey-Hseng; Tsao, Lo-Ti; Chen, Yeh-Long; Tzeng, Cherng-Chyi; Wang, Jih-Pyang

    2005-09-15

    5-[4-Acridin-9-ylamino]phenyl]-5-methyl-3-methylenedihydrofuran-2-one (CYL-26z) inhibited the formyl-Met-Leu-Phe (fMLP)-stimulated phospholipase D (PLD) activity, which was assessed by the production of phosphatidylethanol (PEt) in the presence of ethanol, in rat neutrophils (IC50 1.2+/-0.2 microM). CYL-26z caused a slight but significant attenuation of the global protein tyrosine phosphorylation stimulated by fMLP only at concentrations of CYL-26z up to 30 microM. CYL-26z blocked the membrane recruitment of protein kinase C-alpha (PKC-alpha) at concentrations of CYL-26z > or =3 microM, but failed to affect the membrane association of PKC-betaI and -betaII. The translocation of RhoA to the membrane was attenuated by CYL-26z (IC50 3.8+/-0.8 microM) in fMLP-stimulated neutrophils, whereas CYL-26z caused no significant inhibition of the membrane recruitment of ADP-ribosylation factor (Arf). CYL-26z inhibited the activation of RhoA and dissociation of the RhoA-Rho guanine nucleotide dissociation inhibitor (GDI) complex in fMLP-stimulated neutrophils (IC50 1.8+/-1.0 microM and 1.8+/-0.9 microM, respectively). In a cell-free system, CYL-26z effectively attenuated the membrane association of RhoA in response to GTPgammaS (IC50 1.3+/-0.5 microM). In contrast, the GTPgammaS-stimulated translocation of Arf to membrane was suppressed only at concentrations of CYL-26z up to 30 microM. CYL-26z inhibited the fMLP-stimulated membrane expression of CD11b, CD45 and CD63, and the release of lysozyme and beta-glucuronidase. These results indicate that CYL-26z inhibited the fMLP-stimulated PLD activity, mainly through the blockade of RhoA activation, and degranulation in rat neutrophils.

  14. Remote inhibition of polymer degradation.

    SciTech Connect

    Clough, Roger Lee; Celina, Mathias Christopher

    2005-08-01

    Polymer degradation has been explored on the basis of synergistic infectious and inhibitive interaction between separate materials. A dual stage chemiluminescence detection system with individually controlled hot stages was applied to probe for interaction effects during polymer degradation in an oxidizing environment. Experimental confirmation was obtained that volatile antioxidants can be transferred over a relatively large distance. The thermal degradation of a polypropylene (PP) sample receiving traces of inhibitive antioxidants from a remote source is delayed. Similarly, volatiles from two stabilized elastomers were also capable of retarding a degradation process remotely. This observation demonstrates inhibitive cross-talk as a novel interactive phenomenon between different polymers and is consequential for understanding general polymer interactions, fundamental degradation processes and long-term aging effects of multiple materials in a single environment.

  15. Strigolactone inhibition of shoot branching.

    PubMed

    Gomez-Roldan, Victoria; Fermas, Soraya; Brewer, Philip B; Puech-Pagès, Virginie; Dun, Elizabeth A; Pillot, Jean-Paul; Letisse, Fabien; Matusova, Radoslava; Danoun, Saida; Portais, Jean-Charles; Bouwmeester, Harro; Bécard, Guillaume; Beveridge, Christine A; Rameau, Catherine; Rochange, Soizic F

    2008-09-11

    A carotenoid-derived hormonal signal that inhibits shoot branching in plants has long escaped identification. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Here we present evidence that carotenoid cleavage dioxygenase 8 shoot branching mutants of pea are strigolactone deficient and that strigolactone application restores the wild-type branching phenotype to ccd8 mutants. Moreover, we show that other branching mutants previously characterized as lacking a response to the branching inhibition signal also lack strigolactone response, and are not deficient in strigolactones. These responses are conserved in Arabidopsis. In agreement with the expected properties of the hormonal signal, exogenous strigolactone can be transported in shoots and act at low concentrations. We suggest that endogenous strigolactones or related compounds inhibit shoot branching in plants. Furthermore, ccd8 mutants demonstrate the diverse effects of strigolactones in shoot branching, mycorrhizal symbiosis and parasitic weed interaction.

  16. Substrate inhibition competes with halide inhibition in polyphenol oxidase.

    PubMed

    Lim, Giselle Grace Fernando; Imura, Yuki; Yoshimura, Etsuro

    2012-10-01

    Polyphenol oxidase (PPO) is a ubiquitous enzyme important in the food industry. Although PPO activity followed Michaelis-Menten kinetics at catechol concentrations of up to 1 mM, it slowly decreased at catechol concentrations above 2 mM. This result indicated that in addition to the active site (site A), the enzyme possesses a second catechol-binding site (site B) that exerts an inhibitory effect on PPO activity. Halides inhibit PPO activity in such a way that substrate inhibition is lessened when halide concentration is increased. Furthermore, elevated concentrations of catechol diminished the degree of inhibition by halides. These findings suggest that halides also bind to site B to inhibit PPO activity. A steady-state kinetic analysis demonstrated that the dissociation constant between catechol and PPO depended on the binding of halides to site B. The dissociation constants were greatest when chloride bound to the site. Bromide and iodide yielded lower dissociation constants, in that order. These data indicate that the binding of halide to site B modulated the structure of site A, thereby exerting an inhibitory effect.

  17. Post-Stop-Signal Adjustments: Inhibition Improves Subsequent Inhibition

    ERIC Educational Resources Information Center

    Bissett, Patrick G.; Logan, Gordon D.

    2012-01-01

    Performance in the stop-signal paradigm involves a balance between going and stopping, and one way that this balance is struck is through shifting priority away from the go task, slowing responses after a stop signal, and improving the probability of inhibition. In 6 experiments, the authors tested whether there is a corresponding shift in…

  18. Action spectra for photosynthetic inhibition

    NASA Technical Reports Server (NTRS)

    Caldwell, M. M.; Flint, S.; Camp, L. B.

    1981-01-01

    The ultraviolet action spectrum for photosynthesis inhibition was determined to fall between that of the general DNA action spectrum and the generalized plant action spectrum. The characteristics of this action spectrum suggest that a combination of pronounced increase in effectiveness with decreasing wavelength, substantial specificity for the UV-B waveband, and very diminished response in the UV-A waveband result in large radiation amplification factors when the action spectra are used as weighting functions. Attempted determination of dose/response relationships for leaf disc inhibition provided inconclusive data from which to deconvolute an action spectrum.

  19. Homo economicus belief inhibits trust.

    PubMed

    Xin, Ziqiang; Liu, Guofang

    2013-01-01

    As a foundational concept in economics, the homo economicus assumption regards humans as rational and self-interested actors. In contrast, trust requires individuals to believe partners' benevolence and unselfishness. Thus, the homo economicus belief may inhibit trust. The present three experiments demonstrated that the direct exposure to homo economicus belief can weaken trust. And economic situations like profit calculation can also activate individuals' homo economicus belief and inhibit their trust. It seems that people's increasing homo economicus belief may serve as one cause of the worldwide decline of trust.

  20. Prostacyclin analogs inhibit fibroblast migration.

    PubMed

    Kohyama, Tadashi; Liu, Xiangde; Kim, Hui Jung; Kobayashi, Tetsu; Ertl, Ronald F; Wen, Fu-Qiang; Takizawa, Hajime; Rennard, Stephen I

    2002-08-01

    The controlled accumulation of fibroblasts to sites of inflammation is crucial to effective tissue repair after injury. Either inadequate or excessive accumulation of fibroblasts could result in abnormal tissue function. Prostacyclin (PGI(2)) is a potent mediator in the coagulation and inflammatory processes. The aim of this study was to investigate the effect of PGI(2) on chemotaxis of human fetal lung fibroblasts (HFL-1). Using the blind well chamber technique, we found that the PGI(2) analog carbaprostacyclin (10(-6) M) inhibited HFL-1 chemotaxis to human plasma fibronectin (20 microg/ml) 58.0 +/- 13.2% (P < 0.05) and to platelet-derived growth factor (PDGF)-BB (10 ng/ml) 48.7 +/- 4.6% (P < 0.05). Checkerboard analysis demonstrated that carbaprostacyclin inhibits both directed and undirected migration. The inhibitory effect of the carbaprostacyclin was concentration dependent and blocked by the cAMP-dependent protein kinase (PKA) inhibitor KT-5720, suggesting that a cAMP-PKA pathway may be involved in the process. Two other PGI(2) analogs, ciprostene and dehydro-15-cyclohexyl carbaprostacyclin (both 10(-6) M), significantly inhibited fibroblast migration to fibronectin. In summary, PGI(2) appears to inhibit fibroblast chemotaxis to fibronectin and PDGF-BB. Such an effect may contribute to the regulation of fibroblasts in wound healing and could contribute to the pathogenesis of diseases characterized by abnormal tissue repair remodeling.

  1. Neuronal Inhibition under the Spotlight.

    PubMed

    Mortensen, Martin; Smart, Trevor G

    2015-12-02

    In this issue of Neuron,Lin et al. (2015) report an optical method to precisely manipulate the activity of GABAA receptors by designing a mutant receptor that binds photosensitive compounds. This allows for studying GABAA receptors in situ and represents a valuable tool to investigate how inhibition affects brain physiology.

  2. Tagetitoxin inhibits chloroplast RNA synthesis

    SciTech Connect

    Mathews, D.E.; Durbin, R.D.

    1987-04-01

    Tagetitoxin is a non-host specific phytotoxin which inhibits chloroplast development. Chloroplast encoded gene products as well as their transcripts are conspicuously depleted in toxin-treated tissue. Intact chloroplasts from 8-9 day old peas were incubated for 60 min. in the presence of tagetitoxin. This treatment reduced RNA synthesis but did not affect protein synthesis as measured by the incorporation of radiolabeled uridine or methionine, respectively. Tagetitoxin also inhibited chloroplast RNA synthesis in vitro. Total UTP incorporation was reduced 50% by 0.5..mu..M tagetitoxin in transcriptionally active chloroplast extracts containing 5mg/ml protein. In vitro transcription with purified E. coli RNA polymerase was also inhibited by tagetitoxin, yet wheat germ RNA polymerase II and several bacteriophage RNA polymerase enzymes were unaffected. Recent evidence suggests that RNA polymerase from chloroplasts and prokaryotes may share extensive homology. In light of this evidence and the authors own data, they propose that tagetitoxin directly inhibits chloroplast RNA polymerase.

  3. Inhibition in Prolonged Work Tasks.

    ERIC Educational Resources Information Center

    van der Ven, A. H. G. S.; And Others

    1989-01-01

    A new model is presented that explains reaction time fluctuations in prolonged work tasks. The model extends the so-called Poisson-Erlang model and accounts for long-term trend effects in the reaction time curve. The model is consistent with Spearman's hypothesis that inhibition increases during work and decreases during rest. (TJH)

  4. Inhibition of carcinogenesis by tea.

    PubMed

    Yang, Chung S; Maliakal, Pius; Meng, Xiaofeng

    2002-01-01

    Tea has received a great deal of attention because tea polyphenols are strong antioxidants, and tea preparations have inhibitory activity against tumorigenesis. The bioavailability and biotransformation of tea polyphenols, however, are key factors limiting these activities in vivo. The inhibition of tumorigenesis by green or black tea preparations has been demonstrated in animal models on different organ sites such as skin, lung, oral cavity, esophagus, forestomach, stomach, small intestine, colon, pancreas, and mammary gland. Epidemiological studies, however, have not yielded clear conclusions concerning the protective effects of tea consumption against cancer formation in humans. The discrepancy between the results from humans and animal models could be due to 1) the much higher doses of tea used in animals in comparison to human consumption, 2) the differences in causative factors between the cancers in humans and animals, and 3) confounding factors limiting the power of epidemiological studies to detect an effect. It is possible that tea may be only effective against specific types of cancer caused by certain etiological factors. Many mechanisms have been proposed for the inhibition of carcinogenesis by tea, including the modulation of signal transduction pathways that leads to the inhibition of cell proliferation and transformation, induction of apoptosis of preneoplastic and neoplastic cells, as well as inhibition of tumor invasion and angiogenesis. These mechanisms need to be evaluated and verified in animal models or humans in order to gain more understanding on the effect of tea consumption on human cancer.

  5. Azide inhibition of urate oxidase.

    PubMed

    Gabison, Laure; Colloc'h, Nathalie; Prangé, Thierry

    2014-07-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX-UA or UOX-8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site.

  6. Behavioral Inhibition: Type or Continuum?

    ERIC Educational Resources Information Center

    Scholmerich, Axel; And Others

    This study investigated whether behavioral inhibition is best conceptualized as a continuous variable or as a distinct typology with two or more subcategories. The following data were gathered on 58 infants at 5, 7, 10, and 13 months of age; physiological functioning (cardiovascular activity and salivary cortisol); emotional expressivity in…

  7. Azide inhibition of urate oxidase

    PubMed Central

    Gabison, Laure; Colloc’h, Nathalie; Prangé, Thierry

    2014-01-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX–UA or UOX–8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site. PMID:25005084

  8. Infant Predictors of Behavioural Inhibition

    ERIC Educational Resources Information Center

    Moehler, Eva; Kagan, Jerome; Oelkers-Ax, Rieke; Brunner, Romuald; Poustka, Luise; Haffner, Johann; Resch, Franz

    2008-01-01

    Behavioural inhibition in the second year of life is a hypothesized predictor for shyness, social anxiety and depression in later childhood, adolescence and even adulthood. To search for the earliest indicators of this fundamental temperamental trait, this study examined whether behavioural characteristics in early infancy can predict behavioural…

  9. Cooperative response of keratinocytes and melanocytes to UV radiation during PUVA therapy

    NASA Astrophysics Data System (ADS)

    Stolnitz, Mikhail M.; Baskakov, Pavel V.; Peshkova, Anna Y.

    1999-03-01

    The mathematical model of processes in UV-irradiated furocoumarin-sensitized epidermis is presented taking into account the mutual influence of keratinocytes and melanocytes populations. The model describes epidermis as a hierarchical structure on tissue (keratinocytes-melanocytes cooperation, melanin screen formation), cellular (proliferation and differentiation, transitions between subpopulations), subcellular (cell movement on mitotic cycle, generation, maturing and migration of melanosomes), and molecular (melanin synthesis, processes of DNA damage and repair, molecular signal transduction) levels.

  10. Vam3, a Compound Derived from Vitis amurensis Rupr., Attenuated Colitis-Related Tumorigenesis by Inhibiting NF-κB Signaling Pathway

    PubMed Central

    Xuan, Lingling; Jiang, Rentao; Wu, Zhiyuan; Yi, Honggan; Yao, Chunsuo; Hou, Qi; Qu, Chunfeng

    2016-01-01

    Background: Chronic inflammation is one of the important mediators of colitis-related colon cancer (CRC). Abundant mast cells (MCs) were observed in the tumor microenvironment and mediators released upon MC activation play an important role in the process of chronic inflammation. Previously, we found that activation of intestine mucosal MCs recruited and modulated the inflammatory CD11b+Gr1+ cells to promote the CRC development. In the current study we investigated the effects of Vam3, a resveratrol dimer with potent anti-inflammatory effects, on CRC development. Methods: RBL-2H3 cells, a basophilic leukemia cell line, were pretreated with 2.5 or 5 µM Vam3 and then stimulated with dinitrophenol-conjugated bovine serum albumin (DNP-BSA) plus lipopolysaccharide (LPS). The MC degranulation was determined by measuring β-hexosaminidase release. Generation of TNF-α and IL-6 in RBL-2H3 cells or in peritoneal macrophages was determined by ELISA and real-time qPCR. NF-κB p65 and phospho-NF-κB p65 expression was determined by Western blotting. NF-κB activity in RAW264.7 cells was determined by luciferase reporter assay. CRC was induced in C57BL/6 mice by intraperitoneal injection of azoxymethane (AOM), followed by oral exposure to dextran sodium sulfate (DSS). Vam3 at 50 mg/kg, or disodium cromoglycate (DSCG, MC stabilizer) at 100 mg/kg, or vehicle were administrated to the mice 4 weeks after DSS withdrawal. Levels of TNF-α, IL-6, and mouse MC protease-1 were determined by ELISA. Infiltration of CD11b+Gr1+ cells was determined by flow cytometry analysis. One-way ANOVA was used to compare difference between groups. Results: Pretreatment with Vam3 significantly inhibited RBL-2H3 cell degranulation and inflammatory cytokine production from RBL-2H3 cells and from peritoneal macrophages. After Vam3 treatment, NF-κB activity in RAW264.7 cells, and expressions of phospho-NF-κB p65 in RBL-2H3 cells and in peritoneal macrophages were significantly down-regulated. In the AOM

  11. Inhibition of Retinoblastoma Protein Inactivation

    DTIC Science & Technology

    2015-09-01

    intracellular growth signals to the cell cycle machinery that drives cell division . Inactivation of Rb pathway function is found in most human cancers...Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The objective of this project is to discover and characterize molecules that inhibit breast cancer cell ...proliferation by maintaining activity of the retinoblastoma protein (Rb). Rb is inactivated to drive proliferation in normal and cancer cells by

  12. Conditioned inhibition and reinforcement rate.

    PubMed

    Harris, Justin A; Kwok, Dorothy W S; Andrew, Benjamin J

    2014-07-01

    We investigated conditioned inhibition in a magazine approach paradigm. Rats were trained on a feature negative discrimination between an auditory conditioned stimulus (CS) reinforced at one rate versus a compound of that CS and a visual stimulus (L) reinforced at a lower rate. This training established L as a conditioned inhibitor. We then tested the inhibitory strength of L by presenting it in compound with other auditory CSs. L reduced responding when tested with a CS that had been reinforced at a high rate, but had less or even no inhibitory effect when tested with a CS that had been reinforced at a low rate. The inhibitory strength of L was greater if it signaled a decrease in reinforcement from an already low rate than if it signaled an equivalent decrease in reinforcement from a high rate. We conclude that the strength of inhibition is not a linear function of the change in reinforcement that it signals. We discuss the implications of this finding for models of learning (e.g., Rescorla & Wagner, 1972) that identify inhibition with a difference (subtraction) rule.

  13. Serotonin, Inhibition, and Negative Mood

    PubMed Central

    Dayan, Peter; Huys, Quentin J. M

    2008-01-01

    Pavlovian predictions of future aversive outcomes lead to behavioral inhibition, suppression, and withdrawal. There is considerable evidence for the involvement of serotonin in both the learning of these predictions and the inhibitory consequences that ensue, although less for a causal relationship between the two. In the context of a highly simplified model of chains of affectively charged thoughts, we interpret the combined effects of serotonin in terms of pruning a tree of possible decisions, (i.e., eliminating those choices that have low or negative expected outcomes). We show how a drop in behavioral inhibition, putatively resulting from an experimentally or psychiatrically influenced drop in serotonin, could result in unexpectedly large negative prediction errors and a significant aversive shift in reinforcement statistics. We suggest an interpretation of this finding that helps dissolve the apparent contradiction between the fact that inhibition of serotonin reuptake is the first-line treatment of depression, although serotonin itself is most strongly linked with aversive rather than appetitive outcomes and predictions. PMID:18248087

  14. Complement inhibition in cancer therapy.

    PubMed

    Pio, Ruben; Ajona, Daniel; Lambris, John D

    2013-02-01

    For decades, complement has been recognized as an effector arm of the immune system that contributes to the destruction of tumor cells. In fact, many therapeutic strategies have been proposed that are based on the intensification of complement-mediated responses against tumors. However, recent studies have challenged this paradigm by demonstrating a tumor-promoting role for complement. Cancer cells seem to be able to establish a convenient balance between complement activation and inhibition, taking advantage of complement initiation without suffering its deleterious effects. Complement activation may support chronic inflammation, promote an immunosuppressive microenvironment, induce angiogenesis, and activate cancer-related signaling pathways. In this context, inhibition of complement activation would be a therapeutic option for treating cancer. This concept is relatively new and deserves closer attention. In this article, we summarize the mechanisms of complement activation on cancer cells, the cancer-promoting effect of complement initiation, and the rationale behind the use of complement inhibition as a therapeutic strategy against cancer.

  15. Diterpenoids from Tetraclinis articulata that inhibit various human leukocyte functions.

    PubMed

    Barrero, Alejandro F; Quílez del Moral, José F; Lucas, Rut; Payá, Miguel; Akssira, Mohamed; Akaad, Said; Mellouki, Fouad

    2003-06-01

    Ten new compounds, eight of them pimarane derivatives (1-8), together with a menthane dimer (9) and a totarane diterpenoid (10), were isolated from the leaves and wood of Tetraclinis articulata. The structures of 1-10 were established by using spectroscopic techniques, including 2D NMR spectra. Pimaranes 1-5 were found to possess an unusual cis interannular union of the B and C rings, which, from a biogenetic perspective, could be derived from the hydration of a carbocation at C-8. Compounds 4-6 and a mixture of 7 and 11 modulated different human leukocyte functions at a concentration of 10 microM, mainly the degranulation process measured as myeloperoxidase release and, to a lesser extent, the superoxide production measured by chemiluminescence.

  16. Self-regulation, ego depletion, and inhibition.

    PubMed

    Baumeister, Roy F

    2014-12-01

    Inhibition is a major form of self-regulation. As such, it depends on self-awareness and comparing oneself to standards and is also susceptible to fluctuations in willpower resources. Ego depletion is the state of reduced willpower caused by prior exertion of self-control. Ego depletion undermines inhibition both because restraints are weaker and because urges are felt more intensely than usual. Conscious inhibition of desires is a pervasive feature of everyday life and may be a requirement of life in civilized, cultural society, and in that sense it goes to the evolved core of human nature. Intentional inhibition not only restrains antisocial impulses but can also facilitate optimal performance, such as during test taking. Self-regulation and ego depletion- may also affect less intentional forms of inhibition, even chronic tendencies to inhibit. Broadly stated, inhibition is necessary for human social life and nearly all societies encourage and enforce it.

  17. Chrysin Inhibits Lymphangiogenesis in Vitro.

    PubMed

    Prangsaengtong, Orawin; Athikomkulchai, Sirivan; Xu, Jiuxiang; Koizumi, Keiichi; Inujima, Akiko; Shibahara, Naotoshi; Shimada, Yutaka; Tadtong, Sarin; Awale, Suresh

    2016-01-01

    The induction of lymphangiogenesis is an important process to promote cancer growth and cancer metastasis via the lymphatic system. Identifying the compounds that can prevent lymphangiogenesis for cancer therapy is urgently required. Chrysin, 5,7-dihydroxyflavone, a natural flavone extracted from Thai propolis, was used to investigate the effect on the lymphangiogenesis process of TR-LE, rat lymphatic endothelial cells. In this study, maximal nontoxic doses of chrysin on TR-LE cells were selected by performing a proliferation assay. The process of lymphangiogenesis in vitro was determined by cord formation assay, adhesion assay and migration assay. Chrysin at a nontoxic dose (25 μM) significantly inhibited cord formation, cell adhesion and migration of TR-LE cells when compared with the control group. We also found that chrysin significantly induced vascular endothelial growth factor C (VEGF-C) mRNA expression and nitric oxide (NO) production in TR-LE cells which was involved in decreasing the cord formation of TR-LE cells. In conclusion, we report for the first time that chrysin inhibited the process of lymphangiogenesis in an in vitro model. This finding may prove to be a natural compound for anti-lymphangiogenesis that could be developed for use in cancer therapy.

  18. Graphene: corrosion-inhibiting coating.

    PubMed

    Prasai, Dhiraj; Tuberquia, Juan Carlos; Harl, Robert R; Jennings, G Kane; Rogers, Bridget R; Bolotin, Kirill I

    2012-02-28

    We report the use of atomically thin layers of graphene as a protective coating that inhibits corrosion of underlying metals. Here, we employ electrochemical methods to study the corrosion inhibition of copper and nickel by either growing graphene on these metals, or by mechanically transferring multilayer graphene onto them. Cyclic voltammetry measurements reveal that the graphene coating effectively suppresses metal oxidation and oxygen reduction. Electrochemical impedance spectroscopy measurements suggest that while graphene itself is not damaged, the metal under it is corroded at cracks in the graphene film. Finally, we use Tafel analysis to quantify the corrosion rates of samples with and without graphene coatings. These results indicate that copper films coated with graphene grown via chemical vapor deposition are corroded 7 times slower in an aerated Na(2)SO(4) solution as compared to the corrosion rate of bare copper. Tafel analysis reveals that nickel with a multilayer graphene film grown on it corrodes 20 times slower while nickel surfaces coated with four layers of mechanically transferred graphene corrode 4 times slower than bare nickel. These findings establish graphene as the thinnest known corrosion-protecting coating.

  19. Pharmacological inhibition of poly(ADP-ribose) polymerase inhibits angiogenesis

    SciTech Connect

    Rajesh, Mohanraj; Mukhopadhyay, Partha; Batkai, Sandor; Godlewski, Grzegorz; Hasko, Gyoergy; Liaudet, Lucas; Pacher, Pal . E-mail: pacher@mail.nih.gov

    2006-11-17

    Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme which plays an important role in regulating cell death and cellular responses to DNA repair. Pharmacological inhibitors of PARP are being considered as treatment for cancer both in monotherapy as well as in combination with chemotherapeutic agents and radiation, and were also reported to be protective against untoward effects exerted by certain anticancer drugs. Here we show that pharmacological inhibition of PARP with 3-aminobenzamide or PJ-34 dose-dependently reduces VEGF-induced proliferation, migration, and tube formation of human umbilical vein endothelial cells in vitro. These results suggest that treatment with PARP inhibitors may exert additional benefits in various cancers and retinopathies by decreasing angiogenesis.

  20. Photodynamic effects on T-cells and skin lesions of a patient with mycosis fungoides using porphyrin photosensitizers

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Boehncke, Wolf-Henning; Rueck, Angelika C.; Kaufmann, Roland; Steiner, Rudolf W.; Sterry, Wolfram

    1994-02-01

    PUVA is a well established phototreatment modality for various dermatoses, like T cell lymphomas, using long-wavelength UV radiation. In contrast, PDT bases on the combination of photosensitizers, especially porphyrins, and radiation mainly in the red spectral region. We analyzed the photochemical effects of both treatments on cell lines MyLa and HuT78, established from patients with cutaneous T cell lymphomas. Our observations document the capability of PDT to inhibit proliferation of transformed T cells similar to PUVA thus pointing out its potential in the treatment of cutaneous T cell lymphomas.

  1. Behavioral Inhibition: Temperament or Prodrome?

    PubMed Central

    Pérez-Edgar, Koraly E.; Guyer, Amanda E.

    2014-01-01

    Individual differences in temperament emerge in the first months of life. Some infants display a heightened sensitivity to novelty and uncertainty in the world around them, leading a subset to fearfully withdraw from the social environment. Extreme forms of this temperament, Behavioral Inhibition (BI), are associated with increased risk for social anxiety disorder. Indeed, the link is so strong that some suggest that BI is not simply a risk factor for anxiety, but rather a milder form of the disorder. The current overview describes the literature linking BI and anxiety, highlighting the unique biobehavioral profiles evident in each construct. It then highlights specific evidence that may help distinguish the form and function of BI and anxiety. Finally, we briefly discuss unresolved issues that may help inform future work aimed at improving our understanding of individual development and shape therapeutic interventions directed at specific mechanisms of disorder. PMID:25101234

  2. Suramin inhibits EV71 infection.

    PubMed

    Wang, Yaxin; Qing, Jie; Sun, Yuna; Rao, Zihe

    2014-03-01

    Enterovirus-71 (EV71) is one of the major causative reagents for hand-foot-and-mouth disease. In particular, EV71 causes severe central nervous system infections and leads to numerous dead cases. Although several inactivated whole-virus vaccines have entered in clinical trials, no antiviral agent has been provided for clinical therapy. In the present work, we screened our compound library and identified that suramin, which has been clinically used to treat variable diseases, could inhibit EV71 proliferation with an IC50 value of 40 μM. We further revealed that suramin could block the attachment of EV71 to host cells to regulate the early stage of EV71 infection, as well as affected other steps of EV71 life cycle. Our results are helpful to understand the mechanism for EV71 life cycle and provide a potential for the usage of an approved drug, suramin, as the antiviral against EV71 infection.

  3. Well having inhibited microbial growth

    DOEpatents

    Lee, Brady D.; Dooley, Kirk J.

    2006-08-15

    The invention includes methods of inhibiting microbial growth in a well. A packing material containing a mixture of a first material and an antimicrobial agent is provided to at least partially fill a well bore. One or more access tubes are provided in an annular space around a casing within the well bore. The access tubes have a first terminal opening located at or above a ground surface and have a length that extends from the first terminal opening at least part of the depth of the well bore. The access tubes have a second terminal opening located within the well bore. An antimicrobial material is supplied into the well bore through the first terminal opening of the access tubes. The invention also includes well constructs.

  4. Regulating anxiety with extrasynaptic inhibition

    PubMed Central

    Botta, Paolo; Demmou, Lynda; Kasugai, Yu; Markovic, Milica; Xu, Chun; Fadok, Jonathan P.; Lu, Tingjia; Poe, Michael M.; Xu, Li; Cook, James M.; Rudolph, Uwe; Sah, Pankaj; Ferraguti, Francesco; Lüthi, Andreas

    2015-01-01

    Aversive experiences can lead to complex behavioral adaptations including increased levels of anxiety and fear generalization. The neuronal mechanisms underlying such maladaptive behavioral changes, however, are poorly understood. Here, using a combination of behavioral, physiological and optogenetic approaches in mouse, we identify a specific subpopulation of central amygdala neurons expressing protein kinase C δ (PKCδ) as key elements of the neuronal circuitry controlling anxiety. Moreover, we show that aversive experiences induce anxiety and fear generalization by regulating the activity of PKCδ+ neurons via extrasynaptic inhibition mediated by α5 subunit-containing GABAA receptors. Our findings reveal that the neuronal circuits that mediate fear and anxiety overlap at the level of defined subpopulations of central amygdala neurons and demonstrate that persistent changes in the excitability of a single cell type can orchestrate complex behavioral changes. PMID:26322928

  5. Notch Signaling Inhibits Axon Regeneration

    PubMed Central

    Bejjani, Rachid El; Hammarlund, Marc

    2013-01-01

    Summary Many neurons have limited capacity to regenerate their axons after injury. Neurons in the mammalian CNS do not regenerate, and even neurons in the PNS often fail to regenerate to their former targets. This failure is likely due in part to pathways that actively restrict regeneration; however, only a few factors that limit regeneration are known. Here, using single-neuron analysis of regeneration in vivo, we show that Notch/lin-12 signaling inhibits the regeneration of mature C. elegans neurons. Notch signaling suppresses regeneration by acting autonomously in the injured cell to prevent growth cone formation. The metalloprotease and gamma-secretase cleavage events that lead to Notch activation during development are also required for its activity in regeneration. Furthermore, blocking Notch activation immediately after injury improves regeneration. Our results define a novel, post-developmental role for the Notch pathway as a repressor of axon regeneration in vivo. PMID:22284182

  6. Latent inhibition in human adults without masking.

    PubMed

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R

    2003-09-01

    Latent inhibition refers to attenuated responding to Cue X observed when the X-outcome pairings are preceded by X-alone presentations. It has proven difficult to obtain in human adults unless the preexposure (X-alone) presentations are embedded within a masking (i.e., distracting) task. The authors hypothesized that the difficulty in obtaining latent inhibition with unmasked tasks is related to the usual training procedures, in which the preexposure and conditioning experiences are separated by a set of instructions. Experiment 1 reports latent inhibition without masking in a task in which preexposure and conditioning occur without interruption. Experiments 2 and 3 demonstrate that this attenuation in responding to target Cue X does not pass a summation test for conditioned inhibition and is context specific, thereby confirming that it is latent inhibition. Experiments 3 and 4 confirm that introducing instructions between preexposure and conditioning disrupts latent inhibition.

  7. Inhibition of the dorsal premotor cortex does not repair surround inhibition in writer's cramp patients.

    PubMed

    Veugen, Lidwien C; Hoffland, Britt S; Stegeman, Dick F; van de Warrenburg, Bart P

    2013-03-01

    Writer's cramp is a task-specific form of focal dystonia, characterized by abnormal movements and postures of the hand and arm during writing. Two consistent abnormalities in its pathophysiology are a loss of surround inhibition and overactivity of the dorsal premotor cortex (PMd). This study aimed to assess a possible link between these two phenomena by investigating whether PMd inhibition leads to an improvement of surround inhibition, in parallel with previously demonstrated writing improvement. Fifteen writer's cramp patients and ten controls performed a simple motor hand task during which surround inhibition was measured using transcranial magnetic stimulation. Motor cortical excitability was measured of the active and surround muscles at three phases of the task. Surround inhibition and writing performance were assessed before and after PMd inhibitory continuous theta burst stimulation. In contrast to healthy controls, patients did not show inhibition of the abductor digiti minimi muscle during movement initiation of the first dorsal interosseus muscle, confirming the loss of surround inhibition. PMd inhibition led to an improvement of writing speed in writer's cramp patients. However, in both groups, no changes in surround inhibition were observed. The results confirm a role for the PMd in the pathophysiology of writer's cramp. We show that PMd inhibition does not lead to restoration of the surround inhibition defect in writer's cramp, despite the improvement in writing. This questions the involvement of the PMd in the loss of surround inhibition, and perhaps also the direct link between surround inhibition and dystonia.

  8. The inhibition of acquired fear.

    PubMed

    Izquierdo, Iván; Cammarota, Martín; Vianna, Mónica M R; Bevilaqua, Lía R M

    2004-01-01

    A conditioned stimulus (CS) associated with a fearsome unconditioned stimulus (US) generates learned fear. Acquired fear is at the root of a variety of mental disorders, among which phobias, generalized anxiety, the posttraumatic stress disorder (PTSD) and some forms of depression. The simplest way to inhibit learned fear is to extinguish it, which is usually done by repeatedly presenting the CS alone, so that a new association, CS-"no US", will eventually overcome the previously acquired CS-US association. Extinction was first described by Pavlov as a form of "internal inhibition" and was recommended by Freud and Ferenczi in the 1920s (who called it "habituation") as the treatment of choice for phobic disorders. It is used with success till this day, often in association with anxiolytic drugs. Extinction has since then been applied, also successfully and also often in association with anxiolytics, to the treatment of panic, generalized anxiety disorders and, more recently, PTSD. Extinction of learned fear involves gene expression, protein synthesis, N-methyl-D-aspartate (NMDA) receptors and signaling pathways in the hippocampus and the amygdala at the time of the first CS-no US association. It can be enhanced by increasing the exposure to the "no US" component at the time of behavioral testing, to the point of causing the complete uninstallment of the original fear response. Some theorists have recently proposed that reiteration of the CS alone may induce a reconsolidation of the learned behavior instead of its extinction. Reconsolidation would preserve the original memory from the labilization induced by its retrieval. If true, this would of course be disastrous for the psychotherapy of fear-motivated disorders. Here we show that neither the CS nor retrieval cause anything remotely like reconsolidation, but just extinction. In fact, our findings indicate that the reconsolidation hypothesis is essentially incorrect, at least for the form of contextual fear most

  9. Dimethylphosphoryl-inhibited human cholinesterases: inhibition, reactivation, and aging kinetics.

    PubMed

    Worek, F; Diepold, C; Eyer, P

    1999-02-01

    Human poisoning by organophosphates bearing two methoxy groups, e.g. by malathion, paraoxon-methyl, dimethoate and oxydemeton-methyl, is generally considered to be rather resistant to oxime therapy. Since the oxime effectiveness is influenced not only by its reactivating potential but also by inhibition, aging and spontaneous reactivation kinetics, experiments were performed with human acetyl- (AChE) and butyrylcholinesterase (BChE) to determine the respective kinetic constants. The efficacy of obidoxime in reactivating dimethylphosphoryl-AChE was 40, 9 and 3 times higher than of HI 6, pralidoxime and HLö 7, respectively. Aging (t1/2 3.7 h) and spontaneous reactivation (t1/2 0.7 h) occurred concomitantly, with the portion of the aged enzyme being dependent on the presence of excess inhibitor. Calculation of steady-state AChE activity in the presence of inhibitor and oxime revealed that obidoxime was superior to pralidoxime. In addition, organophosphate concentrations up to 10(-6) M (paraoxon-methyl) and 10(-4) M (oxydemeton-methyl) could be counteracted at clinically relevant oxime concentrations (10 microM). These data indicate that oximes may effectively reactivate human dimethylphosphoryl-AChE. Failure of oximes may be attributed to megadose intoxications and to prolonged time intervals between poison uptake and oxime administration. The potency of the oximes to reactivate dimethylphosphoryl-BChE was much lower and the spontaneous reactivation slower (t1/2 9 h), while aging proceeded at a comparable rate. Thus, BChE activity determination for diagnosis and therapeutic monitoring may give no reliable information on AChE status.

  10. Shed syndecan-2 inhibits angiogenesis

    PubMed Central

    De Rossi, Giulia; Evans, Alun R.; Kay, Emma; Woodfin, Abigail; McKay, Tristan R.; Nourshargh, Sussan; Whiteford, James R.

    2014-01-01

    ABSTRACT Angiogenesis is essential for the development of a normal vasculature, tissue repair and reproduction, and also has roles in the progression of diseases such as cancer and rheumatoid arthritis. The heparan sulphate proteoglycan syndecan-2 is expressed on mesenchymal cells in the vasculature and, like the other members of its family, can be shed from the cell surface resulting in the release of its extracellular core protein. The purpose of this study was to establish whether shed syndecan-2 affects angiogenesis. We demonstrate that shed syndecan-2 regulates angiogenesis by inhibiting endothelial cell migration in human and rodent models and, as a result, reduces tumour growth. Furthermore, our findings show that these effects are mediated by the protein tyrosine phosphatase receptor CD148 (also known as PTPRJ) and this interaction corresponds with a decrease in active β1 integrin. Collectively, these data demonstrate an unexplored pathway for the regulation of new blood vessel formation and identify syndecan-2 as a therapeutic target in pathologies characterised by angiogenesis. PMID:25179601

  11. A Generalized Convective Inhibition Energy

    NASA Astrophysics Data System (ADS)

    Tailleux, R.

    2002-12-01

    The common view about preconvecting soundings is that they possess both CAPE (Convective Available Potential Energy) and CINE (Convective INhibition Energy), the latter preventing the former to be spontaneously released. The two concepts of CAPE and CINE are ambiguous, however, because they depend upon the parcel used to compute the work of buoyancy forces, as well as upon the thermodynamic transformation (adiabatic, pseudo-adiabatic) assumed in lifting the parcel. To remove the ambiguity intrinsically associated with CAPE, Randall and Wang (1992) introduced the concept of GCAPE (Generalized CAPE), defined as the minimum achievable energy difference between the total nonkinetic energy (NKE) of the column of air considered minus the total NKE of a reference soundings obtained by reorganizing the parcels along the vertical by conserving mass. Because the method focuses on how to achieve a global energy minimum without addressing the issue of whether it is achievable or how to achieve it, the concept of CINE is lost. The present work shows how to remedy to this problem, and how to define a Generalized CINE within the same framework serving to define the GCAPE.

  12. Cytokinin inhibition of leaf senescence

    PubMed Central

    Zwack, Paul J.; Rashotte, Aaron M.

    2013-01-01

    The senescence delaying effect of cytokinin is well known, however, the details behind how this process occurs remain unclear. Efforts to improve understanding of this phenomenon have led to the identification in Arabidopsis of specific cytokinin signaling components through which senescence signal responses are regulated. These include the cytokinin receptor (AHK3), the type-B response regulator (ARR2) and the recently identified cytokinin response factor (CRF6). At the mechanistic end of this process, it was found that increased cell-wall invertase activity which occurs in response to cytokinin is both necessary and sufficient for the inhibition of senescence. Yet, a direct link between the signaling and mechanistic steps of a cytokinin regulated senescence process has yet to be demonstrated. This may be in part because the relationship between senescence and primary metabolism implied by the key role of cell-wall invertase is the subject of two apparently opposing bodies of evidence. Here we briefly summarize and propose a model in which cytokinin mediated changes in sink/source relationships leads to delayed senescence which is consistent with existing evidence both for and against sugars as a trigger for developmental senescence. PMID:23656876

  13. [Inhibition of premature uterine contractions].

    PubMed

    Troszyński, M; Leibschang, J; Chazan, B; Adamowicz, R; Brankowska, J

    1979-01-01

    Various drugs used to stop premature uterine contractions are discussed in the paper. Particular attention is paid to beta-mimetic drugs. The results of ming Partusisten, one of beta-mimetic drugs, is presented on the material of 104 patients with threatening immature and premature labour. Partusisten was administered in the form of intravenous drip infusion or tablets. During treatment monitoring of the uterine contractility and of foetal heart rate took place. Inhibition of the uterine contraction activity was successful in 100 per cent of cases. In 60,9 per cent in the group of threatening immature labour and in 38,1 per cent in the group threatening premature labour, the delay of delivery was more then 28 days. The delay of delivery by 48 hours was 87 per cent and 84 per cent in both groups respectively. Tachycardia was one of the first side effects observed in 15,2 per cent of cases. There is also presented an example of pregnancy when delivery was delayed by 21 days in spite of premature outflow of amniotic fluid (at a high rupture of membrane). The authors are of the opinion that Partusisten is very effective and gives little side effects, preventing premature uterine contractions. Dosage should be individualized according to the case and labour advancement, and should be based on topographic evaluation of uterine contraction. Negative influence of the drug on foetuses was not observed.

  14. Allosteric Inhibition Through Core Disruption

    SciTech Connect

    Horn, James R.; Shoichet, Brian K.

    2010-03-05

    Although inhibitors typically bind pre-formed sites on proteins, it is theoretically possible to inhibit by disrupting the folded structure of a protein or, in the limit, to bind preferentially to the unfolded state. Equilibria defining how such molecules act are well understood, but structural models for such binding are unknown. Two novel inhibitors of {beta}-lactamase were found to destabilize the enzyme at high temperatures, but at lower temperatures showed no preference for destabilized mutant enzymes versus stabilized mutants. X-ray crystal structures showed that both inhibitors bound to a cryptic site in {beta}-lactamase, which the inhibitors themselves created by forcing apart helixes 11 and 12. This opened up a portion of the hydrophobic core of the protein, into which these two inhibitors bind. Although this binding site is 16 {angstrom} from the center of the active site, the conformational changes were transmitted through a sequence of linked motions to a key catalytic residue, Arg244, which in the complex adopts conformations very different from those in catalytically competent enzyme conformations. These structures offer a detailed view of what has heretofore been a theoretical construct, and suggest the possibility for further design against this novel site.

  15. Selenium inhibition of chemical carcinogenesis.

    PubMed

    Ip, C

    1985-06-01

    In this article I review the work of our laboratory concerning the relationship between dietary Se intake and susceptibility to mammary carcinogenesis induced by 7,12-dimethylbenz[a]anthracene in female rats. The effect of graded levels of Se in the diet was investigated, ranging from deficiency to excessive supplementation that produced marginal toxicity in the animals. In addition, the interdependence between Se status and fat intake was also explored. Further experiments were aimed at defining the role of Se in the initiation and promotion phases of chemical carcinogenesis. In view of the biochemical function of Se as an antioxidant, the chemopreventive efficacy of Se was compared to that of vitamin E in conjunction with their ability to inhibit lipid peroxidation. Results of this study indicated that the antitumorigenic activity of Se could not be accounted for by suppression of tissue peroxidation, although an environment with a lower oxidant stress might enhance the potency of Se in protecting against cancer. The possible mechanisms of action of Se based on the observations and characteristics of several tumor models are briefly discussed.

  16. Substrate inhibition kinetics of phenol biodegradation

    SciTech Connect

    Goudar, C.T.; Ganji, S.H.; Pujar, B.G.; Strevett, K.A.

    2000-02-01

    Phenol biodegradation was studied in batch experiments using an acclimated inoculum and initial phenol concentrations ranging from 0.1 to 1.3 g/L. Phenol depletion an associated microbial growth were monitored over time to provide information that was used to estimate the kinetics of phenol biodegradation. Phenol inhibited biodegradation at high concentrations, and a generalized substrate inhibition model based on statistical thermodynamics was used to describe the dynamics of microbial growth in phenol. For experimental data obtained in this study, the generalized substrate inhibition model reduced to a form that is analogous to the Andrews equation, and the biokinetic parameters {micro}{sub max}, maximum specific growth; K{sub s}, saturation constant; and K{sub i}, inhibition constant were estimated as 0.251 h{sup {minus}1}, 0.011 g/L, and 0.348 g/L, respectively, using a nonlinear least squares technique. Given the wide variability in substrate inhibition models used to describe phenol biodegradation, an attempt was made to justify selection of particular model based on theoretical considerations. Phenol biodegradation data from nine previously published studies were used in the generalized substrate inhibition model to determine the appropriate form of the substrate inhibition model. In all nine cases, the generalized substrate inhibition model reduced to a form analogous to the Andrews equation suggesting the suitability of the Andrews equation to describe phenol biodegradation data.

  17. A Qualitative Approach to Enzyme Inhibition

    ERIC Educational Resources Information Center

    Waldrop, Grover L.

    2009-01-01

    Most general biochemistry textbooks present enzyme inhibition by showing how the basic Michaelis-Menten parameters K[subscript m] and V[subscript max] are affected mathematically by a particular type of inhibitor. This approach, while mathematically rigorous, does not lend itself to understanding how inhibition patterns are used to determine the…

  18. Quorum sensing inhibition, relevance to periodontics.

    PubMed

    Yada, Sudheer; Kamalesh, B; Sonwane, Siddharth; Guptha, Indra; Swetha, R K

    2015-01-01

    Quorum sensing helps bacteria to communicate with each other and in coordinating their behavior. Many diseases of human beings, plants, and animals are mediated by quorum sensing. Various approaches are being tried to inhibit this communication to control the diseases caused by bacteria. Periodontal pathogens also communicate through quorum sensing and new approaches to treat periodontal disease using quorum sensing inhibition need to explored.

  19. Inhibition: Mental Control Process or Mental Resource?

    ERIC Educational Resources Information Center

    Im-Bolter, Nancie; Johnson, Janice; Ling, Daphne; Pascual-Leone, Juan

    2015-01-01

    The current study tested 2 models of inhibition in 45 children with language impairment and 45 children with normally developing language; children were aged 7 to 12 years. Of interest was whether a model of inhibition as a mental-control process (i.e., executive function) or as a mental resource would more accurately reflect the relations among…

  20. Optimal Decision Making in Neural Inhibition Models

    ERIC Educational Resources Information Center

    van Ravenzwaaij, Don; van der Maas, Han L. J.; Wagenmakers, Eric-Jan

    2012-01-01

    In their influential "Psychological Review" article, Bogacz, Brown, Moehlis, Holmes, and Cohen (2006) discussed optimal decision making as accomplished by the drift diffusion model (DDM). The authors showed that neural inhibition models, such as the leaky competing accumulator model (LCA) and the feedforward inhibition model (FFI), can mimic the…

  1. Hydroxyl radical scavengers inhibit lymphocyte mitogenesis.

    PubMed Central

    Novogrodsky, A; Ravid, A; Rubin, A L; Stenzel, K H

    1982-01-01

    Agents that are known to be scavengers of hydroxyl radicals inhibit lymphocyte mitogenesis induced by phorbol myristate acetate (PMA) to a greater extent than they inhibit mitogenesis induced by concanavalin A or phytohemagglutinin. These agents include dimethyl sulfoxide, benzoate, thiourea, dimethylurea, tetramethylurea, L-tryptophan, mannitol, and several other alcohols. Their inhibitory effect is not associated with cytotoxicity. The hydroxyl radical scavengers do not inhibit PMA-dependent amino acid transport in T cells or PMA-induced superoxide production by monocytes. Thus, they do not inhibit the primary interaction of PMA with responding cells. Treatment of peripheral blood mononuclear cells with PMA increased cellular guanylate cyclase in most experiments, and dimethyl sulfoxide tended to inhibit this increase. In addition to inhibition of PMA-induced mitogenesis, hydroxyl radical scavengers markedly inhibited the activity of lymphocyte activating factor (interleukin 1). The differential inhibition of lymphocyte mitogenesis induced by different mitogens appears to be related to the differential macrophage requirements of the mitogens. The data suggest that hydroxyl radicals may be involved in mediating the triggering signal for lymphocyte activation. Some of the hydroxyl radical scavengers are inducers of cellular differentiation,. nd it is possible that their differentiating activity is related to their ability to scavenge free radicals. PMID:6122209

  2. Amiodarone Inhibits Apamin-Sensitive Potassium Currents

    PubMed Central

    Turker, Isik; Yu, Chih-Chieh; Chang, Po-Cheng; Chen, Zhenhui; Sohma, Yoshiro; Lin, Shien-Fong; Chen, Peng-Sheng; Ai, Tomohiko

    2013-01-01

    Background Apamin sensitive potassium current (IKAS), carried by the type 2 small conductance Ca2+-activated potassium (SK2) channels, plays an important role in post-shock action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (VF) in failing ventricles. Objective To test the hypothesis that amiodarone inhibits IKAS in human embryonic kidney 293 (HEK-293) cells. Methods We used the patch-clamp technique to study IKAS in HEK-293 cells transiently expressing human SK2 before and after amiodarone administration. Results Amiodarone inhibited IKAS in a dose-dependent manner (IC50, 2.67±0.25 µM with 1 µM intrapipette Ca2+). Maximal inhibition was observed with 50 µM amiodarone which inhibited 85.6±3.1% of IKAS induced with 1 µM intrapipette Ca2+ (n = 3). IKAS inhibition by amiodarone was not voltage-dependent, but was Ca2+-dependent: 30 µM amiodarone inhibited 81.5±1.9% of IKAS induced with 1 µM Ca2+ (n = 4), and 16.4±4.9% with 250 nM Ca2+ (n = 5). Desethylamiodarone, a major metabolite of amiodarone, also exerts voltage-independent but Ca2+ dependent inhibition of IKAS. Conclusion Both amiodarone and desethylamiodarone inhibit IKAS at therapeutic concentrations. The inhibition is independent of time and voltage, but is dependent on the intracellular Ca2+ concentration. SK2 current inhibition may in part underlie amiodarone's effects in preventing electrical storm in failing ventricles. PMID:23922993

  3. Hydrogen Sulfide Inhibits Amyloid Formation

    PubMed Central

    2015-01-01

    Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and vascular dementia. The amount of hydrogen sulfide (H2S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H2S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of β-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H2S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550–500 cm–1 spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm–1 band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H2S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils. PMID:25545790

  4. Lysophospholipase inhibition by organophosphorus toxicants.

    PubMed

    Quistad, Gary B; Casida, John E

    2004-05-01

    Lysophospholipases (LysoPLAs) are a large family of enzymes for removing lysophospholipids from cell membranes. Potent inhibitors are needed to define the importance of LysoPLAs as targets for toxicants and potential therapeutics. This study considers organophosphorus (OP) inhibitors with emphasis on mouse brain total LysoPLA activity relative to the mipafox-sensitive neuropathy target esterase (NTE)-LysoPLA recently established as 17% of the total activity and important in the action of OP delayed toxicants. The most potent inhibitors of total LysoPLA in mouse brain are isopropyl dodecylphosphonofluoridate (also for LysoPLA of Vibrio bacteria), ethyl octylphosphonofluoridate (EOPF), and two alkyl-benzodioxaphosphorin 2-oxides (BDPOs)[(S)-octyl and dodecyl] (IC50 2-8 nM). OP inhibitors acting in vitro and in vivo differentiate a more sensitive portion but not a distinct NTE-LysoPLA compared with total LysoPLA activity. For 10 active inhibitors, NTE-LysoPLA is 17-fold more sensitive than total LysoPLA, but structure-activity comparisons give a good correlation (r(2) = 0.94) of IC50 values, suggesting active site structural similarity or identity. In mice 4 h after intraperitoneal treatment with discriminating doses, EOPF, tribufos (a plant defoliant), and dodecanesulfonyl fluoride inhibit 41-57% of the total brain LysoPLA and 85-99% of the NTE-LysoPLA activity. Total LysoPLA as well as NTE-LysoPLA is decreased in activity in Nte(+/-)-haploinsufficient mice compared to their Nte(+/+) littermates. The lysolecithin level of spinal cord but not brain is elevated significantly following EOPF treatment (3 mg/kg), thereby focusing attention on localized rather than general alterations in lysophospholipid metabolism in OP-induced hyperactivity and toxicity.

  5. Cardiac remodelling and RAS inhibition

    PubMed Central

    Ferrario, Carlos M.

    2016-01-01

    Risk factors such as hypertension and diabetes are known to augment the activity and tissue expression of angiotensin II (Ang II), the major effector peptide of the renin–angiotensin system (RAS). Overstimulation of the RAS has been implicated in a chain of events that contribute to the pathogenesis of cardiovascular (CV) disease, including the development of cardiac remodelling. This chain of events has been termed the CV continuum. The concept of CV disease existing as a continuum was first proposed in 1991 and it is believed that intervention at any point within the continuum can modify disease progression. Treatment with antihypertensive agents may result in regression of left ventricular hypertrophy, with different drug classes exhibiting different degrees of efficacy. The greatest decrease in left ventricular mass is observed following treatment with angiotensin converting enzyme inhibitors (ACE-Is), which inhibit Ang II formation. Although ACE-Is and angiotensin receptor blockers (ARBs) provide significant benefits in terms of CV events and stroke, mortality remains high. This is partly due to a failure to completely suppress the RAS, and, as our knowledge has increased, an escape phenomenon has been proposed whereby the human sequence of the 12 amino acid substrate angiotensin-(1-12) is converted to Ang II by the mast cell protease, chymase. Angiotensin-(1-12) is abundant in a wide range of organs and has been shown to increase blood pressure in animal models, an effect abolished by the presence of ACE-Is or ARBs. This review explores the CV continuum, in addition to examining the influence of the RAS. We also consider novel pathways within the RAS and how new therapeutic approaches that target this are required to further reduce Ang II formation, and so provide patients with additional benefits from a more complete blockade of the RAS. PMID:27105891

  6. Habituation, latent inhibition, and extinction.

    PubMed

    Jordan, Wesley P; Todd, Travis P; Bucci, David J; Leaton, Robert N

    2015-06-01

    In two conditioned suppression experiments with a latent inhibition (LI) design, we measured the habituation of rats in preexposure, their LI during conditioning, and then extinction over days. In the first experiment, lick suppression, the preexposed group (PE) showed a significant initial unconditioned response (UR) to the target stimulus and significant long-term habituation (LTH) of that response over days. The significant difference between the PE and nonpreexposed (NPE) groups on the first conditioning trial was due solely to the difference in their URs to the conditioned stimulus (CS)-a habituated response (PE) and an unhabituated response (NPE). In the second experiment, bar-press suppression, little UR to the target stimulus was apparent during preexposure, and no detectable LTH. Thus, there was no difference between the PE and NPE groups on the first conditioning trial. Whether the UR to the CS confounds the interpretation of LI (Exp. 1) or not (Exp. 2) can only be known if the UR is measured. In both experiments, LI was observed in acquisition. Also in both experiments, rats that were preexposed and then conditioned to asymptote were significantly more resistant to extinction than were the rats not preexposed. This result contrasts with the consistently reported finding that preexposure either produces less resistance to extinction or has no effect on extinction. The effect of stimulus preexposure survived conditioning to asymptote and was reflected directly in extinction. These two experiments provide a cautionary procedural note for LI experiments and have shown an unexpected extinction effect that may provide new insights into the interpretation of LI.

  7. Praziquantel inhibits Schistosoma mansoni attachment in vitro.

    PubMed

    da-Silva, S P; Noel, F

    1990-01-01

    Male adult Schistosoma mansoni worms were placed in a glass dish containing Tyrode solution and observed for 15 min after addition of praziquantel (0.01 to 1 microM). Praziquantel promoted a concentration- and time-dependent inhibition of sucker-mediated attachment of the worm. Attachment inhibition was correlated with shortening of the parasite. We propose that the rapid and total inhibition of worm attachment observed in vitro with 1 microM praziquantel indicates that therapeutic concentrations of this drug should promote a rapid hepatic shift, in vivo, which may facilitate host tissue reaction.

  8. Lobelane inhibits methamphetamine-evoked dopamine release via inhibition of the vesicular monoamine transporter-2.

    PubMed

    Nickell, Justin R; Krishnamurthy, Sairam; Norrholm, Seth; Deaciuc, Gabriela; Siripurapu, Kiran B; Zheng, Guangrong; Crooks, Peter A; Dwoskin, Linda P

    2010-02-01

    Lobeline is currently being evaluated in clinical trials as a methamphetamine abuse treatment. Lobeline interacts with nicotinic receptor subtypes, dopamine transporters (DATs), and vesicular monoamine transporters (VMAT2s). Methamphetamine inhibits VMAT2 and promotes dopamine (DA) release from synaptic vesicles, resulting ultimately in increased extracellular DA. The present study generated structure-activity relationships by defunctionalizing the lobeline molecule and determining effects on [(3)H]dihydrotetrabenazine binding, inhibition of [(3)H]DA uptake into striatal synaptic vesicles and synaptosomes, the mechanism of VMAT2 inhibition, and inhibition of methamphetamine-evoked DA release. Compared with lobeline, the analogs exhibited greater potency inhibiting DA transporter (DAT) function. Saturated analogs, lobelane and nor-lobelane, exhibited high potency (K(i) = 45 nM) inhibiting vesicular [(3)H]DA uptake, and lobelane competitively inhibited VMAT2 function. Lobeline and lobelane exhibited 67- and 35-fold greater potency, respectively, in inhibiting VMAT2 function compared to DAT function. Lobelane potently decreased (IC(50) = 0.65 microM; I(max) = 73%) methamphetamine-evoked DA overflow, and with a greater maximal effect compared with lobeline (IC(50) = 0.42 microM, I(max) = 56.1%). These results provide support for VMAT2 as a target for inhibition of methamphetamine effects. Both trans-isomers and demethylated analogs of lobelane had reduced or unaltered potency inhibiting VMAT2 function and lower maximal inhibition of methamphetamine-evoked DA release compared with lobelane. Thus, defunctionalization, cis-stereochemistry of the side chains, and presence of the piperidino N-methyl are structural features that afford greatest inhibition of methamphetamine-evoked DA release and enhancement of selectivity for VMAT2. The current results reveal that lobelane, a selective VMAT2 inhibitor, inhibits methamphetamine-evoked DA release and is a promising lead for

  9. Glycerol inhibition of ruminal lipolysis in vitro

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Supplemental glycerol inhibits rumen lipolysis, a prerequisite for rumen biohydrogenation, which is responsible for the saturation of dietary fatty acids consumed by ruminant animals. Feeding excess glycerol, however, adversely affects dry matter digestibility. To more clearly define the effect of...

  10. TNF inhibition as therapy for rheumatoid arthritis.

    PubMed

    Wollheim, Frank A

    2002-07-01

    The introduction of TNF- alpha -inhibiting biologicals has been a major therapeutic breakthrough in rheumatoid arthritis therapy. Against a background of conventional disease-modifying antirheumatic drug experience, this review focuses on present experiences and possible future developments. TNF inhibition results in profound improvement in the majority of rheumatoid arthritis patients, but non-response and adverse effects need attention. Adalimumab is being filed for approval. Other monoclonal antibodies or receptor constructs are in late development. Small molecule inhibitors of TNF production or signalling are a hot topic. One emerging target is nuclear factor kappa B and selective inhibition has proved effective in animal models of arthritis. Synovial proliferation in rheumatoid arthritis is characterised by diminished apoptosis of fibroblasts, whereas bone marrow precursor cells undergo accelerated apoptosis in active rheumatoid arthritis. Both abnormalities are seemingly ameliorated by TNF inhibition. Anti-apoptotic strategies will soon go into development for control of unresponsive rheumatoid arthritis.

  11. Inhibition of urinary calculi -- a spectroscopic study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia; Govani, Jayesh; Durrer, William; Reza, Layra; Pinales, Luis

    2008-10-01

    Although a considerable number of investigations have already been undertaken and many causes such as life habits, metabolic disorders, and genetic factors have been noted as sources that accelerate calculi depositions and aggregations, there are still plenty of unanswered questions regarding efficient inhibition and treatment mechanisms. Thus, in an attempt to acquire more insights, we propose here a detailed scientific study of kidney stone formation and growth inhibition based on a traditional medicine approach with Rotula Aquatica Lour (RAL) herbal extracts. A simplified single diffusion gel growth technique was used for synthesizing the samples for the present study. The unexpected Zn presence in the sample with RAL inhibitor, as revealed by XPS measurements, explains the inhibition process and the dramatic reflectance of the incident light observed in the infrared transmission studies. Raman data demonstrate potential binding of the inhibitor with the oxygen of the kidney stone. Photoluminescence results corroborate to provide additional evidence of Zn-related inhibition.

  12. Toxicants inhibiting anaerobic digestion: a review.

    PubMed

    Chen, Jian Lin; Ortiz, Raphael; Steele, Terry W J; Stuckey, David C

    2014-12-01

    Anaerobic digestion is increasingly being used to treat wastes from many sources because of its manifold advantages over aerobic treatment, e.g. low sludge production and low energy requirements. However, anaerobic digestion is sensitive to toxicants, and a wide range of compounds can inhibit the process and cause upset or failure. Substantial research has been carried out over the years to identify specific inhibitors/toxicants, and their mechanism of toxicity in anaerobic digestion. In this review we present a detailed and critical summary of research on the inhibition of anaerobic processes by specific organic toxicants (e.g., chlorophenols, halogenated aliphatics and long chain fatty acids), inorganic toxicants (e.g., ammonia, sulfide and heavy metals) and in particular, nanomaterials, focusing on the mechanism of their inhibition/toxicity. A better understanding of the fundamental mechanisms behind inhibition/toxicity will enhance the wider application of anaerobic digestion.

  13. Quorum Sensing Inhibition, Relevance to Periodontics

    PubMed Central

    Yada, Sudheer; Kamalesh, B; Sonwane, Siddharth; Guptha, Indra; Swetha, R K

    2015-01-01

    Quorum sensing helps bacteria to communicate with each other and in coordinating their behavior. Many diseases of human beings, plants, and animals are mediated by quorum sensing. Various approaches are being tried to inhibit this communication to control the diseases caused by bacteria. Periodontal pathogens also communicate through quorum sensing and new approaches to treat periodontal disease using quorum sensing inhibition need to explored. PMID:25709373

  14. Inhibited solid propellant composition containing beryllium hydride

    NASA Technical Reports Server (NTRS)

    Thompson, W. W. (Inventor)

    1978-01-01

    An object of this invention is to provide a composition of beryllium hydride and carboxy-terminated polybutadiene which is stable. Another object of this invention is to provide a method for inhibiting the reactivity of beryllium hydride toward carboxy-terminated polybutadiene. It was found that a small amount of lecithin inhibits the reaction of beryllium hydride with the acid groups in carboxy terminated polybutadiene.

  15. Inhibition of Heme Peroxidases by Melamine

    PubMed Central

    Vanachayangkul, Pattaraporn; Tolleson, William H.

    2012-01-01

    In 2008 melamine-contaminated infant formula and dairy products in China led to over 50,000 hospitalizations of children due to renal injuries. In North America during 2007 and in Asia during 2004, melamine-contaminated pet food products resulted in numerous pet deaths due to renal failure. Animal studies have confirmed the potent renal toxicity of melamine combined with cyanuric acid. We showed previously that the solubility of melamine cyanurate is low at physiologic pH and ionic strength, provoking us to speculate how toxic levels of these compounds could be transported through the circulation without crystallizing until passing into the renal filtrate. We hypothesized that melamine might be sequestered by heme proteins, which could interfere with heme enzyme activity. Four heme peroxidase enzymes were selected for study: horseradish peroxidase (HRP), lactoperoxidase (LPO), and cyclooxygenase-1 and -2 (COX-1 and -2). Melamine exhibited noncompetitive inhibition of HRP (Ki  9.5 ± 0.7 mM), and LPO showed a mixed model of inhibition (Ki  14.5 ± 4.7 mM). The inhibition of HRP and LPO was confirmed using a chemiluminescent peroxidase assay. Melamine also exhibited COX-1 inhibition, but inhibition of COX-2 was not detected. Thus, our results demonstrate that melamine inhibits the activity of three heme peroxidases. PMID:22852071

  16. Inhibition of chymotrypsin by heparin cofactor II.

    PubMed Central

    Church, F C; Noyes, C M; Griffith, M J

    1985-01-01

    Human heparin cofactor II is a plasma protein that is known to inhibit thrombin. The rate of thrombin inhibition by heparin cofactor II is accelerated (greater than or equal to 1000-fold) in the presence of the glycosaminoglycans, heparin and dermatan sulfate. We have found that chymotrypsin A alpha is also inhibited by heparin cofactor II with a second-order rate constant value of 1.8 X 10(6) M-1 X min-1 at pH 8.0 and 25 degrees C. However, there was no measurable effect of heparin or dermatan sulfate on the rate of chymotrypsin inhibition. Arginine-modified heparin cofactor II showed a comparable percentage loss of both antichymotrypsin and antithrombin activities. Heparin cofactor II and chymotrypsin formed a stable complex with a Mr value near 90,000 when analyzed by NaDodSO4/polyacrylamide gel electrophoresis; this suggests a 1:1 reaction stoichiometry. The chymotrypsin cleavage site in heparin cofactor II was the same as that for thrombin, and primary structure analysis of the inhibitor showed a P'1-P'8 sequence of Ser-Thr-Gln-Val-Arg-Phe-Thr-Val ... . The results indicate that, in contrast to alpha 1-antichymotrypsin, which does not inhibit trypsin-like enzymes, including thrombin, heparin cofactor II can effectively inhibit both thrombin and chymotrypsin. PMID:3863104

  17. Piperine, a dietary phytochemical, inhibits angiogenesis

    PubMed Central

    Doucette, Carolyn D.; Hilchie, Ashley L.; Liwski, Robert; Hoskin, David W.

    2012-01-01

    Angiogenesis plays an important role in tumor progression. Piperine, a major alkaloid constituent of black pepper, has diverse physiological actions including killing of cancer cells; however, the effect of piperine on angiogenesis is not known. Here we show that piperine inhibited the proliferation and G1/S transition of human umbilical vein endothelial cells (HUVECs) without causing cell death. Piperine also inhibited HUVEC migration and tubule formation in vitro, as well as collagen-induced angiogenic activity by rat aorta explants and breast cancer cell-induced angiogenesis in chick embryos. Although piperine binds to and activates the cation channel transient receptor potential vanilloid 1 (TRPV1), its effects on endothelial cells did not involve TRPV1 since the antiproliferative effect of piperine was not affected by TRPV1-selective antagonists, nor did HUVECs express detectable TRPV1 mRNA. Importantly, piperine inhibited phosphorylation of Ser 473 and Thr 308 residues of Akt (protein kinase B), which is a key regulator of endothelial cell function and angiogenesis. Consistent with Akt inhibition as the basis of piperine’s action on HUVECs, inhibition of the phosphoinositide-3 kinase/Akt signaling pathway with LY-294002 also inhibited HUVEC proliferation and collagen-induced angiogenesis. Taken together, these data support the further investigation of piperine as an angiogenesis inhibitor for use in cancer treatment. PMID:22902327

  18. Inhibition in the Human Auditory Cortex

    PubMed Central

    Inui, Koji; Nakagawa, Kei; Nishihara, Makoto; Motomura, Eishi; Kakigi, Ryusuke

    2016-01-01

    Despite their indispensable roles in sensory processing, little is known about inhibitory interneurons in humans. Inhibitory postsynaptic potentials cannot be recorded non-invasively, at least in a pure form, in humans. We herein sought to clarify whether prepulse inhibition (PPI) in the auditory cortex reflected inhibition via interneurons using magnetoencephalography. An abrupt increase in sound pressure by 10 dB in a continuous sound was used to evoke the test response, and PPI was observed by inserting a weak (5 dB increase for 1 ms) prepulse. The time course of the inhibition evaluated by prepulses presented at 10–800 ms before the test stimulus showed at least two temporally distinct inhibitions peaking at approximately 20–60 and 600 ms that presumably reflected IPSPs by fast spiking, parvalbumin-positive cells and somatostatin-positive, Martinotti cells, respectively. In another experiment, we confirmed that the degree of the inhibition depended on the strength of the prepulse, but not on the amplitude of the prepulse-evoked cortical response, indicating that the prepulse-evoked excitatory response and prepulse-evoked inhibition reflected activation in two different pathways. Although many diseases such as schizophrenia may involve deficits in the inhibitory system, we do not have appropriate methods to evaluate them; therefore, the easy and non-invasive method described herein may be clinically useful. PMID:27219470

  19. Relationships between inhibition constants, inhibitor concentrations for 50% inhibition and types of inhibition: new ways of analysing data.

    PubMed Central

    Cortés, A; Cascante, M; Cárdenas, M L; Cornish-Bowden, A

    2001-01-01

    The concentration of an inhibitor that decreases the rate of an enzyme-catalysed reaction by 50%, symbolized i(0.5), is often used in pharmacological studies to characterize inhibitors. It can be estimated from the common inhibition plots used in biochemistry by means of the fact that the extrapolated inhibitor concentration at which the rate becomes infinite is equal to -i(0.5). This method is, in principle, more accurate than comparing the rates at various different inhibitor concentrations, and inferring the value of i(0.5) by interpolation. Its reciprocal, 1/i(0.5), is linearly dependent on v(0)/V, the uninhibited rate divided by the limiting rate, and the extrapolated value of v(0)/V at which 1/i(0.5) is zero allows the type of inhibition to be characterized: this value is 1 if the inhibition is strictly competitive; greater than 1 if the inhibition is mixed with a predominantly competitive component; infinite (i.e. 1/i(0.5) does not vary with v(0)/V) if the inhibition is pure non-competitive (i.e. mixed with competitive and uncompetitive components equal); negative if the inhibition is mixed with a predominantly uncompetitive component; and zero if it is strictly uncompetitive. The type of analysis proposed has been tested experimentally by examining inhibition of lactate dehydrogenase by oxalate (an uncompetitive inhibitor with respect to pyruvate) and oxamate (a competitive inhibitor with respect to pyruvate), and of cytosolic malate dehydrogenase by hydroxymalonate (a mixed inhibitor with respect to oxaloacetate). In all cases there is excellent agreement between theory and experiment. PMID:11415458

  20. Influence of ethanolic extract of Tephrosia purpurea Linn. on mast cells and erythrocytes membrane integrity.

    PubMed

    Gokhale, A B; Dikshit, V J; Damre, A S; Kulkarni, K R; Saraf, M N

    2000-08-01

    The ethanolic extract of T. purpurea Linn. was studied for its in vitro effect on rat mast cell degranulation and erythrocyte membrane integrity in vitro. The extract in concentration of 25-200 microg/ml showed a dose-dependant inhibition of rat mast cell degranulation induded by compound 48/80 and egg albumin. T. purpurea extract was found to inhibit haemolysis of erythrocytes induced by hypotonic solution but accelerated haemolysis induced by heat at a concentration of 100 microg/ml. The studies reveal that the ethanolic extract of T. purpurea may inhibit degranulation of mast cells by a mechanism other than membrane stabilization.

  1. Iminosugars Inhibit Dengue Virus Production via Inhibition of ER Alpha-Glucosidases—Not Glycolipid Processing Enzymes

    PubMed Central

    Sayce, Andrew C.; Alonzi, Dominic S.; Killingbeck, Sarah S.; Tyrrell, Beatrice E.; Hill, Michelle L.; Caputo, Alessandro T.; Iwaki, Ren; Kinami, Kyoko; Ide, Daisuke; Kiappes, J. L.; Beatty, P. Robert; Kato, Atsushi; Harris, Eva; Dwek, Raymond A.; Miller, Joanna L.; Zitzmann, Nicole

    2016-01-01

    It has long been thought that iminosugar antiviral activity is a function of inhibition of endoplasmic reticulum-resident α-glucosidases, and on this basis, many iminosugars have been investigated as therapeutic agents for treatment of infection by a diverse spectrum of viruses, including dengue virus (DENV). However, iminosugars are glycomimetics possessing a nitrogen atom in place of the endocyclic oxygen atom, and the ubiquity of glycans in host metabolism suggests that multiple pathways can be targeted via iminosugar treatment. Successful treatment of patients with glycolipid processing defects using iminosugars highlights the clinical exploitation of iminosugar inhibition of enzymes other than ER α-glucosidases. Evidence correlating antiviral activity with successful inhibition of ER glucosidases together with the exclusion of alternative mechanisms of action of iminosugars in the context of DENV infection is limited. Celgosivir, a bicyclic iminosugar evaluated in phase Ib clinical trials as a therapeutic for the treatment of DENV infection, was confirmed to be antiviral in a lethal mouse model of antibody-enhanced DENV infection. In this study we provide the first evidence of the antiviral activity of celgosivir in primary human macrophages in vitro, in which it inhibits DENV secretion with an EC50 of 5 μM. We further demonstrate that monocyclic glucose-mimicking iminosugars inhibit isolated glycoprotein and glycolipid processing enzymes and that this inhibition also occurs in primary cells treated with these drugs. By comparison to bicyclic glucose-mimicking iminosugars which inhibit glycoprotein processing but do not inhibit glycolipid processing and galactose-mimicking iminosugars which do not inhibit glycoprotein processing but do inhibit glycolipid processing, we demonstrate that inhibition of endoplasmic reticulum-resident α-glucosidases, not glycolipid processing, is responsible for iminosugar antiviral activity against DENV. Our data suggest that

  2. Chemical inhibition of nitrification in activated sludge.

    PubMed

    Kelly, R T; Henriques, I D S; Love, N G

    2004-03-20

    Conventional aerobic nitrification was adversely affected by single pulse inputs of six different classes of industrially relevant chemical toxins: an electrophilic solvent (1-chloro-2,4-dinitrobenzene, CDNB), a heavy metal (cadmium), a hydrophobic chemical (1-octanol), an uncoupling agent (2,4-dinitrophenol, DNP), alkaline pH, and cyanide in its weak metal complexed form. The concentrations of each chemical source that caused 1 5, 25, and 50% respiratory inhibition of a nitrifying mixed liquor during a short-term assay were used to shock sequencing batch reactors containing nitrifying conventional activated sludge. The reactors were monitored for recovery over a period of 30 days or less. All shock conditions inhibited nitrification, but to different degrees. The nitrate generation rate (NGR) of the shocked reactors recovered overtime to control reactor levels and showed that it was a more sensitive indicator of nitrification inhibition than both initial respirometric tests conducted on unexposed biomass and effluent nitrogen species analyses. CDNB had the most severe impact on nitrification, followed by alkaline pH 11, cadmium, cyanide, octanol, and DNP. Based on effluent data, cadmium and octanol primarily inhibited ammonia-oxidizing bacteria (AOB) while CDNB, pH 11,and cyanide inhibited both AOB and nitrite-oxidizing bacteria (NOB). DNP initially inhibited nitrification but quickly increased the NGR relative to the control and stimulated nitrification after several days in a manner reflective of oxidative uncoupling. The shocked mixed liquor showed trends toward recovery from inhibition for all chemicals tested, but in some cases this reversion was slow. These results contribute to our broader effort to identify relationships between chemical sources and the process effects they induce in activated sludge treatment systems.

  3. Targeting Angiotensin II Type-1 Receptor (AT1R) Inhibits the Harmful Phenotype of Plasmodium-Specific CD8+ T Cells during Blood-Stage Malaria

    PubMed Central

    Silva-Filho, João L.; Caruso-Neves, Celso; Pinheiro, Ana A. S.

    2017-01-01

    CD8+ T-cell response is critical in the pathogenesis of cerebral malaria during blood-stage. Our group and other have been shown that angiotensin II (Ang II) and its receptor AT1 (AT1R), a key effector axis of renin-angiotensin system (RAS), have immune regulatory effects on T cells. Previously, we showed that inhibition of AT1R signaling protects mice against the lethal disease induced by Plasmodium berghei ANKA infection However, most of the Ang II/AT1R actions were characterized by using only pharmacological approaches, the effects of which may not always be due to a specific receptor blockade. In addition, the mechanisms of action of the AT1R in inducing the pathogenic activity of Plasmodium-specific CD8+ T cells during blood-stage were not determined. Here, we examined how angiotensin II/AT1R axis promotes the harmful response of Plasmodium-specific CD8+ T-cell during blood-stage by using genetic and pharmacological approaches. We evaluated the response of wild-type (WT) and AT1R−/− Plasmodium-specific CD8+ T cells in mice infected with a transgenic PbA lineage expressing ovalbumin; and in parallel infected mice receiving WT Plasmodium-specific CD8+ T cells were treated with losartan (AT1R antagonist) or captopril (ACE inhibitor). Both, AT1R−/− OT-I cells and WT OT-I cells from losartan- or captopril-treated mice showed lower expansion, reduced IL-2 production and IL-2Rα expression, lower activation (lower expression of CD69, CD44 and CD160) and lower exhaustion profiles. AT1R−/− OT-I cells also exhibit lower expression of the integrin LFA-1 and the chemokine receptors CCR5 and CXCR3, known to play a key role in the development of cerebral malaria. Moreover, AT1R−/− OT-I cells produce lower amounts of IFN-γ and TNF-α and show lower degranulation upon restimulation. In conclusion, our results show the pivotal mechanisms of AT1R-induced harmful phenotype of Plasmodium-specific CD8+ T cells during blood-stage malaria. PMID:28261571

  4. Targeting Angiotensin II Type-1 Receptor (AT1R) Inhibits the Harmful Phenotype of Plasmodium-Specific CD8(+) T Cells during Blood-Stage Malaria.

    PubMed

    Silva-Filho, João L; Caruso-Neves, Celso; Pinheiro, Ana A S

    2017-01-01

    CD8(+) T-cell response is critical in the pathogenesis of cerebral malaria during blood-stage. Our group and other have been shown that angiotensin II (Ang II) and its receptor AT1 (AT1R), a key effector axis of renin-angiotensin system (RAS), have immune regulatory effects on T cells. Previously, we showed that inhibition of AT1R signaling protects mice against the lethal disease induced by Plasmodium berghei ANKA infection However, most of the Ang II/AT1R actions were characterized by using only pharmacological approaches, the effects of which may not always be due to a specific receptor blockade. In addition, the mechanisms of action of the AT1R in inducing the pathogenic activity of Plasmodium-specific CD8(+) T cells during blood-stage were not determined. Here, we examined how angiotensin II/AT1R axis promotes the harmful response of Plasmodium-specific CD8(+) T-cell during blood-stage by using genetic and pharmacological approaches. We evaluated the response of wild-type (WT) and AT1R(-/-)Plasmodium-specific CD8(+) T cells in mice infected with a transgenic PbA lineage expressing ovalbumin; and in parallel infected mice receiving WT Plasmodium-specific CD8(+) T cells were treated with losartan (AT1R antagonist) or captopril (ACE inhibitor). Both, AT1R(-/-) OT-I cells and WT OT-I cells from losartan- or captopril-treated mice showed lower expansion, reduced IL-2 production and IL-2Rα expression, lower activation (lower expression of CD69, CD44 and CD160) and lower exhaustion profiles. AT1R(-/-) OT-I cells also exhibit lower expression of the integrin LFA-1 and the chemokine receptors CCR5 and CXCR3, known to play a key role in the development of cerebral malaria. Moreover, AT1R(-/-) OT-I cells produce lower amounts of IFN-γ and TNF-α and show lower degranulation upon restimulation. In conclusion, our results show the pivotal mechanisms of AT1R-induced harmful phenotype of Plasmodium-specific CD8(+) T cells during blood-stage malaria.

  5. Inhibition of pear fruit ripening by mannose.

    PubMed

    Watkins, C B; Frenkel, C

    1987-09-01

    Softening of the flesh and the rise in ethylene evolution and respiration associated with ripening in pear (Pyrus communis L.) fruit was delayed when mannose was vacuum infiltrated into intact fruit. The extent of delay could be modified by altering the concentration or the volume of mannose applied to the fruit. Inhibition of ripening was associated with phosphorylation of mannose to mannose 6-phosphate (M6P), and accumulation of M6P was associated with lowered levels of inorganic phosphate (Pi), glucose 6-phosphate (G6P), and ATP in the fruit tissue. Subsequently, however, as the M6P was metabolized, the levels of Pi, G6P, and ATP increased and ripening processes were concomitantly released from inhibition. Hence, the degree of inhibition by mannose or the release from inhibition was related to the level of M6P in the fruit and its rate of metabolism. The data provide correlative evidence to support a view that one inhibitory effect of mannose is depletion of Pi in the cell as a result of phosphorylation of mannose to M6P. Inhibition of ripening by mannose was not alleviated by co-application of glucose as a competitive substrate for the hexokinase(s), or by Pi, presumably the depleted metabolite. Also, incubation of tissue disks with M6P resulted in inhibition of ethylene production and respiration. The structural analogs of mannose, glucosamine, and 2-deoxyglucose, which have been shown to mimic mannose action in several plant tissues, did not cause inhibition of ripening of pear fruit comparable with that associated with mannose. Both analogs stimulated respiration, and glucosamine caused only a small inhibition of softening and ethylene evolution. Another mannose analog, alpha-methylmannoside, did inhibit fruit ripening though to a lesser extent than mannose. Its influence was also associated with accumulation of M6P and a decrease of Pi levels. We conclude that the mannose effect may, in part, be due to M6P toxicity, as well as by depletion of Pi.

  6. Calcium inhibits diacylglycerol uptake by serum albumin.

    PubMed

    Ahyayauch, Hasna; Arana, Gorka; Sot, Jesús; Alonso, Alicia; Goñi, Félix M

    2009-03-01

    Serum albumin is an abundant protein in blood plasma, that is well-known for its ability to transport hydrophobic biomolecules and drugs. Recent hypotheses propose that serum albumin plays a role in the regulation of lipid metabolism in addition to its lipid transport properties. The present work explores the capacity of bovine serum albumin (BSA) to extract diacylglycerols (DAG) from phospholipid bilayers, and the inhibition of such interaction by divalent cations. Quantitative measurements using radioactive DAG and morphological evidence derived from giant unilamellar vesicles examined by confocal microscopy provide concurrent results. BSA extracts DAG from vesicles consisting of phosphatidylinositol/DAG. Long, saturated DAG species are incorporated more readily than the shorter-chain or unsaturated ones. Divalent cations hinder DAG uptake by BSA. For Ca(2+), the concentration causing half-maximal inhibition is approximately 10 muM; 90% inhibition is caused by 100 muM Ca(2+). Sr(2+) requires concentrations one order of magnitude higher, while Mg(2+) has virtually no effect. As an example on how DAG uptake by BSA, and its inhibition by Ca(2+), could play a regulating role in lipid metabolism, a PI-specific phospholipase C has been assayed in the presence of BSA and/or Ca(2+). BSA activates the enzyme by removing the end-product DAG, but the activation is reverted by Ca(2+) that inhibits DAG uptake.

  7. Speech-induced modulation of interhemispheric inhibition.

    PubMed

    Kano, Tadashige; Kobayashi, Masahito; Ohira, Takayuki; Yoshida, Kazunari

    2012-12-07

    This study aimed to determine the effects of speech and mastication on interhemispheric inhibition between the right and left primary motor areas (M1s) by using transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were recorded from the first dorsal interossei (FDIs) of each hand of 10 healthy right-handed subjects under 3 conditions: at rest (control), during mastication (non-verbal oral movement), and during speech (reading aloud). Test TMS was delivered following conditioning TMS of the contralateral M1 at various interstimulus intervals. Under all conditions, the MEPs in the left FDIs were significantly inhibited after conditioning of the left M1 (i.e. inhibition of the right M1 by TMS of the left hemisphere). In contrast, the left M1 was significantly inhibited by the right hemisphere only during the control and mastication tasks, but not speech task. These results suggest that speech may facilitate the activity of the dominant M1 via functional connectivity between the speech area and the left M1, or may modify the balance of interhemispheric interactions, by suppressing inhibition of the dominant hemisphere by the non-dominant hemisphere. Our findings show a novel aspect of interhemispheric dominance and may improve therapeutic strategies for recovery from stroke.

  8. Response inhibition in motor conversion disorder.

    PubMed

    Voon, Valerie; Ekanayake, Vindhya; Wiggs, Edythe; Kranick, Sarah; Ameli, Rezvan; Harrison, Neil A; Hallett, Mark

    2013-05-01

    Conversion disorders (CDs) are unexplained neurological symptoms presumed to be related to a psychological issue. Studies focusing on conversion paralysis have suggested potential impairments in motor initiation or execution. Here we studied CD patients with aberrant or excessive motor movements and focused on motor response inhibition. We also assessed cognitive measures in multiple domains. We compared 30 CD patients and 30 age-, sex-, and education-matched healthy volunteers on a motor response inhibition task (go/no go), along with verbal motor response inhibition (color-word interference) and measures of attention, sustained attention, processing speed, language, memory, visuospatial processing, and executive function including planning and verbal fluency. CD patients had greater impairments in commission errors on the go/no go task (P < .001) compared with healthy volunteers, which remained significant after Bonferroni correction for multiple comparisons and after controlling for attention, sustained attention, depression, and anxiety. There were no significant differences in other cognitive measures. We highlight a specific deficit in motor response inhibition that may play a role in impaired inhibition of unwanted movement such as the excessive and aberrant movements seen in motor conversion. Patients with nonepileptic seizures, a different form of conversion disorder, are commonly reported to have lower IQ and multiple cognitive deficits. Our results point toward potential differences between conversion disorder subgroups. © 2013 Movement Disorder Society.

  9. Response Inhibition in Motor Conversion Disorder

    PubMed Central

    Voon, Valerie; Ekanayake, Vindhya; Wiggs, Edythe; Kranick, Sarah; Ameli, Rezvan; Harrison, Neil A.; Hallett, Mark

    2014-01-01

    Conversion disorders (CDs) are unexplained neurological symptoms presumed to be related to a psychological issue. Studies focusing on conversion paralysis have suggested potential impairments in motor initiation or execution. Here we studied CD patients with aberrant or excessive motor movements and focused on motor response inhibition. We also assessed cognitive measures in multiple domains. We compared 30 CD patients and 30 age-, sex-, and education-matched healthy volunteers on a motor response inhibition task (go/no go), along with verbal motor response inhibition (color-word interference) and measures of attention, sustained attention, processing speed, language, memory, visuospatial processing, and executive function including planning and verbal fluency. CD patients had greater impairments in commission errors on the go/no go task (P <.001) compared with healthy volunteers, which remained significant after Bonferroni correction for multiple comparisons and after controlling for attention, sustained attention, depression, and anxiety. There were no significant differences in other cognitive measures. We highlight a specific deficit in motor response inhibition that may play a role in impaired inhibition of unwanted movement such as the excessive and aberrant movements seen in motor conversion. Patients with nonepileptic seizures, a different form of conversion disorder, are commonly reported to have lower IQ and multiple cognitive deficits. Our results point toward potential differences between conversion disorder subgroups. PMID:23554084

  10. Magnesium inhibition of calcite dissolution kinetics

    SciTech Connect

    Arvidson, Rolf S.; Collier, Martin; Davis, Kevin J.; Vinson, Michael D.; Amonette, James E.; Luttge, Andreas

    2006-02-01

    We present evidence of inhibition of calcite dissolution by dissolved magnesium through direct observations of the (104) surface using atomic force microscopy (AFM) and vertical scanning interferometry (VSI). Far from equilibrium, the pattern of magnesium inhibition is dependent on solution composition and specific to surface step geometry. In CO2-free solutions (pH 8.8), dissolved magnesium brings about little inhibition even at concentrations of 0.8 x 10-3 molal. At the same pH, magnesium concentrations of less than 0.05 x 10-3 molal in carbonate-buffered solutions generate significant inhibition, although no changes in surface and etch pit morphology are observed. As concentrations exceed magnesite saturation, the dissolution rate shows little additional decrease; however, selective pinning of step edges results in unique etch-pit profiles, seen in both AFM and VSI datasets. Despite the decreases in step velocity, magnesium addition in carbonated solutions also appears to activate the surface by increasing the nucleation rate of new defects. These relationships suggest that the modest depression of the bulk rate measured by VSI reflects a balance between competing reaction mechanisms that simultaneously depress the rate through selective inhibition of step movement, but also enhance reactivity on terraces by lowering the energy barrier to new etch-pit formation.

  11. Inhibition of ethylene production by putrescine alleviates aluminium-induced root inhibition in wheat plants

    PubMed Central

    Yu, Yan; Jin, Chongwei; Sun, Chengliang; Wang, Jinghong; Ye, Yiquan; Zhou, Weiwei; Lu, Lingli; Lin, Xianyong

    2016-01-01

    Inhibition of root elongation is one of the most distinct symptoms of aluminium (Al) toxicity. Although putrescine (Put) has been identified as an important signaling molecule involved in Al tolerance, it is yet unknown how Put mitigates Al-induced root inhibition. Here, the possible mechanism was investigated by using two wheat genotypes differing in Al resistance: Al-tolerant Xi Aimai-1 and Al-sensitive Yangmai-5. Aluminium caused more root inhibition in Yangmai-5 and increased ethylene production at the root apices compared to Xi Aimai-1, whereas the effects were significantly reversed by ethylene biosynthesis inhibitors. The simultaneous exposure of wheat seedlings to Al and ethylene donor, ethephon, or ethylene biosynthesis precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), increased ethylene production and aggravated root inhibition, which was more pronounced in Xi Aimai-1. In contrast, Put treatment decreased ethylene production and alleviated Al-induced root inhibition in both genotypes, and the effects were more conspicuous in Yangmai-5. Furthermore, our results indicated that Al-induced ethylene production was mediated by ACC synthase (ACS) and ACC oxidase, and that Put decreased ethylene production by inhibiting ACS. Altogether, these findings indicate that ethylene is involved in Al-induced root inhibition and this process could be alleviated by Put through inhibiting ACS activity. PMID:26744061

  12. Inhibition of mTOR pathway attenuates migration and invasion of gallbladder cancer via EMT inhibition.

    PubMed

    Zong, Huajie; Yin, Baobing; Zhou, Huading; Cai, Duan; Ma, Baojin; Xiang, Yang

    2014-07-01

    Gallbladder cancer (GBC) is an aggressive disease in which epithelial-mesenchymal transition (EMT) plays a critical role. Whether inhibition of mTOR effects via EMT reversal in GBC remains unclear. Using genetic and pharmacologic inhibitions of mTOR, we investigated the changes of EMT levels in GBC cells. Expressions of EMT related genes were also studied. Migration and invasion assays were carried out and in vivo tumour metastasis mouse models were established. Circulating tumour DNA was quantified. We used EMT index (ratio of Vimentin/Ecadherin expression) to profile EMT levels. We found that inhibition of mTOR using shRNAs and rapamycin inhibited EMT in GBC-SD gallbladder cancer cells. Inhibition of mTOR inhibited EMT in GBC-SD cells in TGF-β-dependent manner, which was contributed majorly by mTORC2 inhibition. Rapamycin decreased invasiveness and migration of GBC-SD cells in vitro and in vivo. We have in the current study shown that rapamycin diminishes the ability of invasion and migration of GBC via inhibition of TGF-β-dependent EMT. Our findings contribute to the understanding of the carcinogenesis of GBC.

  13. Inhibition of ethylene production by putrescine alleviates aluminium-induced root inhibition in wheat plants.

    PubMed

    Yu, Yan; Jin, Chongwei; Sun, Chengliang; Wang, Jinghong; Ye, Yiquan; Zhou, Weiwei; Lu, Lingli; Lin, Xianyong

    2016-01-08

    Inhibition of root elongation is one of the most distinct symptoms of aluminium (Al) toxicity. Although putrescine (Put) has been identified as an important signaling molecule involved in Al tolerance, it is yet unknown how Put mitigates Al-induced root inhibition. Here, the possible mechanism was investigated by using two wheat genotypes differing in Al resistance: Al-tolerant Xi Aimai-1 and Al-sensitive Yangmai-5. Aluminium caused more root inhibition in Yangmai-5 and increased ethylene production at the root apices compared to Xi Aimai-1, whereas the effects were significantly reversed by ethylene biosynthesis inhibitors. The simultaneous exposure of wheat seedlings to Al and ethylene donor, ethephon, or ethylene biosynthesis precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), increased ethylene production and aggravated root inhibition, which was more pronounced in Xi Aimai-1. In contrast, Put treatment decreased ethylene production and alleviated Al-induced root inhibition in both genotypes, and the effects were more conspicuous in Yangmai-5. Furthermore, our results indicated that Al-induced ethylene production was mediated by ACC synthase (ACS) and ACC oxidase, and that Put decreased ethylene production by inhibiting ACS. Altogether, these findings indicate that ethylene is involved in Al-induced root inhibition and this process could be alleviated by Put through inhibiting ACS activity.

  14. The role of (dis)inhibition in creativity: decreased inhibition improves idea generation.

    PubMed

    Radel, Rémi; Davranche, Karen; Fournier, Marion; Dietrich, Arne

    2015-01-01

    There is now a large body of evidence showing that many different conditions related to impaired fronto-executive functioning are associated with the enhancement of some types of creativity. In this paper, we pursue the possibility that the central mechanism associated with this effect might be a reduced capacity to exert inhibition. We tested this hypothesis by exhausting the inhibition efficiency through prolonged and intensive practice of either the Simon or the Eriksen Flanker task. Performance on another inhibition task indicated that only the cognitive resources for inhibition of participants facing high inhibition demands were impaired. Subsequent creativity tests revealed that exposure to high inhibition demands led to enhanced fluency in a divergent thinking task (Alternate Uses Task), but no such changes occurred in a convergent task (Remote Associate Task; studies 1a and 1b). The same manipulation also led to a hyper-priming effect for weakly related primes in a Lexical Decision Task (Study 2). Together, these findings suggest that inhibition selectively affects some types of creative processes and that, when resources for inhibition are lacking, the frequency and the originality of ideas was facilitated.

  15. Complete corrosion inhibition through graphene defect passivation.

    PubMed

    Hsieh, Ya-Ping; Hofmann, Mario; Chang, Kai-Wen; Jhu, Jian Gang; Li, Yuan-Yao; Chen, Kuang Yao; Yang, Chang Chung; Chang, Wen-Sheng; Chen, Li-Chyong

    2014-01-28

    Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ∼50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.

  16. Inhibiting macrophage proliferation suppresses atherosclerotic plaque inflammation.

    PubMed

    Tang, Jun; Lobatto, Mark E; Hassing, Laurien; van der Staay, Susanne; van Rijs, Sarian M; Calcagno, Claudia; Braza, Mounia S; Baxter, Samantha; Fay, Francois; Sanchez-Gaytan, Brenda L; Duivenvoorden, Raphaël; Sager, Hendrik; Astudillo, Yaritzy M; Leong, Wei; Ramachandran, Sarayu; Storm, Gert; Pérez-Medina, Carlos; Reiner, Thomas; Cormode, David P; Strijkers, Gustav J; Stroes, Erik S G; Swirski, Filip K; Nahrendorf, Matthias; Fisher, Edward A; Fayad, Zahi A; Mulder, Willem J M

    2015-04-01

    Inflammation drives atherosclerotic plaque progression and rupture, and is a compelling therapeutic target. Consequently, attenuating inflammation by reducing local macrophage accumulation is an appealing approach. This can potentially be accomplished by either blocking blood monocyte recruitment to the plaque or increasing macrophage apoptosis and emigration. Because macrophage proliferation was recently shown to dominate macrophage accumulation in advanced plaques, locally inhibiting macrophage proliferation may reduce plaque inflammation and produce long-term therapeutic benefits. To test this hypothesis, we used nanoparticle-based delivery of simvastatin to inhibit plaque macrophage proliferation in apolipoprotein E deficient mice (Apoe(-/-) ) with advanced atherosclerotic plaques. This resulted in rapid reduction of plaque inflammation and favorable phenotype remodeling. We then combined this short-term nanoparticle intervention with an eight-week oral statin treatment, and this regimen rapidly reduced and continuously suppressed plaque inflammation. Our results demonstrate that pharmacologically inhibiting local macrophage proliferation can effectively treat inflammation in atherosclerosis.

  17. Inhibiting macrophage proliferation suppresses atherosclerotic plaque inflammation

    PubMed Central

    Tang, Jun; Lobatto, Mark E.; Hassing, Laurien; van der Staay, Susanne; van Rijs, Sarian M.; Calcagno, Claudia; Braza, Mounia S.; Baxter, Samantha; Fay, Francois; Sanchez-Gaytan, Brenda L.; Duivenvoorden, Raphaël; Sager, Hendrik B.; Astudillo, Yaritzy M.; Leong, Wei; Ramachandran, Sarayu; Storm, Gert; Pérez-Medina, Carlos; Reiner, Thomas; Cormode, David P.; Strijkers, Gustav J.; Stroes, Erik S. G.; Swirski, Filip K.; Nahrendorf, Matthias; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.

    2015-01-01

    Inflammation drives atherosclerotic plaque progression and rupture, and is a compelling therapeutic target. Consequently, attenuating inflammation by reducing local macrophage accumulation is an appealing approach. This can potentially be accomplished by either blocking blood monocyte recruitment to the plaque or increasing macrophage apoptosis and emigration. Because macrophage proliferation was recently shown to dominate macrophage accumulation in advanced plaques, locally inhibiting macrophage proliferation may reduce plaque inflammation and produce long-term therapeutic benefits. To test this hypothesis, we used nanoparticle-based delivery of simvastatin to inhibit plaque macrophage proliferation in apolipoprotein E–deficient mice (Apoe−/−) with advanced atherosclerotic plaques. This resulted in the rapid reduction of plaque inflammation and favorable phenotype remodeling. We then combined this short-term nanoparticle intervention with an 8-week oral statin treatment, and this regimen rapidly reduced and continuously suppressed plaque inflammation. Our results demonstrate that pharmacologically inhibiting local macrophage proliferation can effectively treat inflammation in atherosclerosis. PMID:26295063

  18. Mesoporous silica nanoparticles inhibit cellular respiration.

    PubMed

    Tao, Zhimin; Morrow, Matthew P; Asefa, Tewodros; Sharma, Krishna K; Duncan, Cole; Anan, Abhishek; Penefsky, Harvey S; Goodisman, Jerry; Souid, Abdul-Kader

    2008-05-01

    We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O 2 consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500 microg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 microg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 microg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both nanoparticles inhibited respiration of isolated mitochondria and submitochondrial particles.

  19. Zerumbone, Sesquiterpene Photochemical from Ginger, Inhibits Angiogenesis

    PubMed Central

    Park, Ju-Hyung; Park, Geun Mook

    2015-01-01

    Here, we investigated the role of zerumbone, a natural cyclic sesquiterpene of Zingiber zerumbet Smith, on angiogenesis using human umbilical vein endothelial cells (HUVECs). Zerumbone inhibited HUVECs proliferation, migration and tubule formation, as well as angiogenic activity by rat aorta explants. In particular, zerumbone inhibited phosphorylation of vascular endothelial growth factor receptor-2 and fibroblast growth factor receptor-1, which are key regulators of endothelial cell function and angiogenesis. In vivo matrigel plug assay in mice demonstrated significant decrease in vascularization and hemoglobin content in the plugs from zerumbone-treated mice, compared with control mice. Overall, these results suggest that zerumbone inhibits various attributes of angiogenesis, which might contribute to its reported antitumor effects. PMID:26170737

  20. Inhibition of renal alkaline phosphatase by cimetidine.

    PubMed

    Minai-Tehrani, Dariush; Khodai, Somayeh; Aminnaseri, Somayeh; Minoui, Saeed; Sobhani-Damavadifar, Zahra; Alavi, Sana; Osmani, Raheleh; Ahmadi, Shiva

    2011-08-01

    Alkaline phosphatase (ALP) belongs to hydrolase group of enzymes. It is responsible for removing phosphate groups from many types of molecules, including nucleotides and proteins. Cimetidine (trade name Tagamet) is an antagonist of histamine H2-receptor that inhibits the production of gastric acid. Cimetidine is used for the treatment of gastrointestinal diseases. In this study the inhibitory effect of cimetidine on mouse renal ALP activity was investigated. Our results showed that cimetidine can inhibit ALP by uncompetitive inhibition. In the absence of inhibitor the V(max) and K(m) of the enzyme were found to be 13.7 mmol/mg prot.min and 0.25 mM, respectively. Both the Vmax and Km of the enzyme decreased with increasing cimetidine concentrations (0- 1.2 mM). The Ki and IC(50) of cimetidine were determined to be about 0.5 mM and 0.52 mM, respectively.

  1. Terbinafine inhibits gap junctional intercellular communication.

    PubMed

    Lee, Ju Yeun; Yoon, Sei Mee; Choi, Eun Ju; Lee, Jinu

    2016-09-15

    Terbinafine is an antifungal agent that selectively inhibits fungal sterol synthesis by blocking squalene epoxidase. We evaluated the effect of terbinafine on gap junctional intercellular communication (GJIC). Fluorescence recovery after photobleaching (FRAP) and I-YFP GJIC assays revealed that terbinafine inhibits GJIC in a reversible and dose-dependent manner in FRT-Cx43 and LN215 cells. Treatment with terbinafine did not affect Cx43 phosphorylation status or intracellular Ca(2+) concentration, well-known action mechanisms of various GJIC blockers. While a structurally related chemical, naftifine, attenuated GJIC, epigallocatechin gallate, another potent squalene epoxidase inhibitor with a different structure, did not. These results suggest that terbinafine inhibits GJIC with a so far unknown mechanism of action.

  2. Inhibition of Henipavirus infection by RNA interference.

    PubMed

    Mungall, Bruce A; Schopman, Nick C T; Lambeth, Luke S; Doran, Tim J

    2008-12-01

    Nipah virus (NiV) and Hendra virus (HeV) are recently emerged zoonotic paramyxoviruses exclusively grouped within a new genus, Henipavirus. These viruses cause fatal disease in a wide range of species, including humans. Both NiV and HeV have continued to re-emerge sporadically in Bangladesh and Australia, respectively. There are currently no therapeutics or vaccines available to treat Henipavirus infection and both are classified as BSL4 pathogens. RNA interference (RNAi) is a process by which double-stranded RNA directs sequence-specific degradation of messenger RNA in animal and plant cells. Small interfering RNAs (siRNAs) mediate RNAi by inhibiting gene expression of homologous mRNA and our preliminary studies suggest RNAi may be a useful approach to developing novel therapies for these highly lethal pathogens. Eight NiV siRNA molecules (four L and four N gene specific), two HeV N gene specific, and two non-specific control siRNA molecules were designed and tested for their ability to inhibit a henipavirus minigenome replication system (which does not require the use of live virus) in addition to live virus infections in vitro. In the minigenome assay three out of the four siRNAs that targeted the L gene of NiV effectively inhibited replication. In contrast, only NiV N gene siRNAs were effective in reducing live NiV replication, suggesting inhibition of early, abundantly expressed gene transcripts may be more effective than later, less abundant transcripts. Additionally, some of the siRNAs effective against NiV infection were only partially effective inhibitors of HeV infection. An inverse correlation between the number of nucleotide mismatches and the efficacy of siRNA inhibition was observed. The demonstration that RNAi effectively inhibits henipavirus replication in vitro, is a novel approach and may provide an effective therapy for these highly lethal, zoonotic pathogens.

  3. Pyrilamine inhibits nicotine-induced catecholamine secretion.

    PubMed

    Kim, Dong-Chan; Yun, So Jeong; Park, Yong-Soo; Jun, Dong-Jae; Kim, Dongjin; Jiten Singh, N; Kim, Sanguk; Kim, Kyong-Tai

    2014-07-01

    Function of nicotine, which induces activation of all parts of the body including our brain, has been receiving much attention for a long period of time and also been actively studied by researchers for its pharmacological actions in the central nervous system. The modulation of nicotine concentration and the inhibition of nicotine binding on target receptors in the brain are the key factors for smoking addiction therapy. In previous studies showed that influx of nicotine at the blood-brain barrier was through the pyrilamine-sensitive organic cation transporters. But the direct interacting mechanism of pyrilamine on the nicotine binding target receptors has not yet been clarified. The aim of the present study is to investigate the direct binding mechanisms of a pyrilamine on the nicotinic acetylcholine receptors (nAChRs). We found that pyrilamine shares the same ligand binding pocket of nicotine (NCT) on nAChRs but interacts with more amino acid residues than NCT does. The extended part of pyrilamine interacts with additional residues in the ligand binding pocket of nAChRs which are located nearby the entrance of the binding pocket. The catecholamine (CA) secretion induced by nAChR agonist (NCT') was significantly inhibited by the pyrilamine pretreatment. Real time carbon-fiber amperometry confirmed the inhibition of the NCT'-induced exocytosis by pyrilamine in a single cell level. We also found that pyrilamine inhibited the NCT'-induced [Ca(2+)]i. In contrast, pyrilamine did not affect the increase in calcium induced by high K(+). Overall, these data suggest that pyrilamine directly docks into the ligand binding site of nAChRs and specifically inhibits the nAChR-mediated effects thereby causing inhibition of CA secretion. Therefore, pyrilamine may play an important role to explore new treatments to aid smoking cessation.

  4. DNA-Targeted Inhibition of MGMT.

    PubMed

    Luedtke, Nathan William; Marsoner, Theodor; Schmidt, Olivia; Trimer, Therese

    2017-02-08

    The cationic porphyrin 5,10,15,20-tetrakis (diisopropyl-guanidine)-21H,23H-porphine "DIGPor" selectively binds to DNA containing O6-methylguanine (O6-MeG) and inhibits the DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT). The O6-MeG selectivity and MGMT inhibitory activity of DIGPor was improved by incorporating ZnII into the porphyrin. The resulting metal complex "Zn-DIGPor" potentiated the activity of the DNA alkylating drug temozolomide in an MGMT-expressing cell line. To the best of our knowledge, these results provide the first examples of DNA-targeted MGMT inhibition.

  5. Inhibition of aflatoxin formation by some spices.

    PubMed

    Mabrouk, S S; El-Shayeb, N M

    1980-01-01

    The effects of black pepper, cinnamon, peppermint, cumin, ginger and clove on growth and aflatoxin formation of Aspergillus flavus were studied in rice powdercorn steep (RC) medium. The effects of the first five spices were judged to be inhibition of aflatoxin formation rather than of mycelial growth. Clove completely inhibited both mycelial growth and aflatoxin formation at a concentration above 0.1%. No aflatoxin was produced when cumin and mint levels of 5% and 10% were used. Black pepper and ginger levels of 10% decreased aflatoxin formation by 100%. Higher concentrations of cinnamon, mint, cumin and ginger stimulated mycelial growth.

  6. Bacterial contact-dependent growth inhibition (CDI)

    PubMed Central

    Ruhe, Zachary C.; Low, David A.; Hayes, Christopher S.

    2013-01-01

    Bacteria cooperate to form multicellular communities and compete against one another for environmental resources. Here, we review recent advances in our understanding of bacterial competition mediated by contact-dependent growth inhibition (CDI) systems. Different CDI+ bacteria deploy a variety of toxins to inhibit neighboring cells and protect themselves from autoinhibition by producing specific immunity proteins. The genes encoding CDI toxin–immunity pairs appear to be exchanged between cdi loci and are often associated with other toxin-delivery systems in diverse bacteria. CDI also appears to facilitate cooperative behavior between kin, suggesting that these systems may have other roles beyond competition. PMID:23473845

  7. Rust inhibiting additive compositions for oils

    SciTech Connect

    Haugen, H.

    1980-09-23

    Compositions which include mixtures of a calcium hydroxide overbased oil-soluble calcium sulfonate, hexylene glycol and a surfactant consisting of an ethoxylated aliphatic amine, particularly, diethoxylated cocoamine or diethoxylated soyamine, are useful as rust inhibiting additives for oils and the like. By incorporating these compositions in petroleum based oils such as petroleum based oils of lubricating oil quality which come into contact with metal surfaces under conditions such that the metal surfaces tend to rust or otherwise be subject to deterioration it is possible to inhibit rust formation on such metal surfaces.

  8. A quick method for the determination of inhibition constants.

    PubMed Central

    Waley, S G

    1982-01-01

    The inhibition constant Ki in the common case of competitive inhibition can be obtained by simple comparison of progress curves in the presence and in the absence of inhibitor. The difference between the times taken for the concentration of substrate to fall to the same value is used to obtain Ki. The procedure to use when the product inhibits is described. When there is mixed inhibition, reactions at different substrate concentrations are used to obtain both inhibition constants. PMID:7150236

  9. Lipophilic chelator inhibition of electron transport in Escherichia coli.

    PubMed Central

    Crane, R T; Sun, I L; Crane, F L

    1975-01-01

    The lipophilic chelator bathophenanthroline inhibits electron transport in membranes from Escherichia coli. The less lipophilic 1,10-phenanthroline, bathophenanthroline sulfonate, and alpha,alpha-dipyridyl have little effect. Reduced nicotinamide adenine dinucleotide oxidase is more sensitive to bathophenanthroline inhibition than lactate oxidase activity. Evidence for two sites of inhibition comes from the fact that both reduced nicotinamide adenine dinucleotide menadione reductase and duroquinol oxidase activities are inhibited. Addition of uncouplers of phosphorylation before bathophenanthroline protects against inhibition. PMID:1092663

  10. Target Predictability, Sustained Attention, and Response Inhibition

    ERIC Educational Resources Information Center

    Carter, Leonie; Russell, Paul N.; Helton, William S.

    2013-01-01

    We examined whether the sustained attention to response task is a better measure of response inhibition or sustained attention. Participants performed a number detection task for 37.3 min using either a Sustained Attention to Response Task (SART; high Go low No-Go) or a more traditionally formatted vigilance task (TFT; high No-Go low Go) response…

  11. Nickel inhibits mitochondrial fatty acid oxidation.

    PubMed

    Uppala, Radha; McKinney, Richard W; Brant, Kelly A; Fabisiak, James P; Goetzman, Eric S

    2015-08-07

    Nickel exposure is associated with changes in cellular energy metabolism which may contribute to its carcinogenic properties. Here, we demonstrate that nickel strongly represses mitochondrial fatty acid oxidation-the pathway by which fatty acids are catabolized for energy-in both primary human lung fibroblasts and mouse embryonic fibroblasts. At the concentrations used, nickel suppresses fatty acid oxidation without globally suppressing mitochondrial function as evidenced by increased glucose oxidation to CO2. Pre-treatment with l-carnitine, previously shown to prevent nickel-induced mitochondrial dysfunction in neuroblastoma cells, did not prevent the inhibition of fatty acid oxidation. The effect of nickel on fatty acid oxidation occurred only with prolonged exposure (>5 h), suggesting that direct inhibition of the active sites of metabolic enzymes is not the mechanism of action. Nickel is a known hypoxia-mimetic that activates hypoxia inducible factor-1α (HIF1α). Nickel-induced inhibition of fatty acid oxidation was blunted in HIF1α knockout fibroblasts, implicating HIF1α as one contributor to the mechanism. Additionally, nickel down-regulated the protein levels of the key fatty acid oxidation enzyme very long-chain acyl-CoA dehydrogenase (VLCAD) in a dose-dependent fashion. In conclusion, inhibition of fatty acid oxidation by nickel, concurrent with increased glucose metabolism, represents a form of metabolic reprogramming that may contribute to nickel-induced carcinogenesis.

  12. Aromatase Inhibition in a Transcriptional Network Context

    EPA Science Inventory

    A variety of chemicals in the environment have the potential to inhibit aromatase, an enzyme critical to estrogen synthesis. We examined the responses of female fathead minnow ovaries (FHM, Pimephales promelas) to a model aromatase inhibitor, fadrozole, using a transcriptional ne...

  13. Nitrite inhibition of denitrification by Pseudomonas fluorescens

    SciTech Connect

    Almeida, J.S.; Julio, S.M.; Reis, M.A.M. |

    1995-05-05

    Using a pure culture of Pseudomonas fluorescens as a model system nitrite inhibition of denitrification was studied. A mineral media with acetate and nitrate as sole electron donor and acceptor, respectively, was used. Results obtained in continuous stirred-tank reactors (CSTR) operated at pH values between 6.6 and 7.8 showed that growth inhibition depended only on the nitrite undissociated fraction concentration (nitrous acid). A mathematical model to describe this dependence is put forward. The maximum nitrous acid concentration compatible with cell growth and denitrification activity was found to be 66 {mu}g N/L. Denitrification activity was partially associated with growth, as described by the Luedeking-Piret equation. However, when the freshly inoculated reactor was operated discontinuously, nitrite accumulation caused growth uncoupling from denitrification activity. The authors suggest that these results can be interpreted considering that (a) nitrous acid acts as a proton uncoupler; and (b) cultures continuously exposed to nitrous acid prevent the uncoupling effect but not the growth inhibition. Examination of the growth dependence on nitrite concentration at pH 7.0 showed that adapted cultures (growth on CSTR) are less sensitive to nitrous acid inhibition than the ones cultivated in batch.

  14. Epoxygenated Fatty Acids Inhibit Retinal Vascular Inflammation

    PubMed Central

    Capozzi, Megan E.; Hammer, Sandra S.; McCollum, Gary W.; Penn, John S.

    2016-01-01

    The objective of the present study was to assess the effect of elevating epoxygenated fatty acids on retinal vascular inflammation. To stimulate inflammation we utilized TNFα, a potent pro-inflammatory mediator that is elevated in the serum and vitreous of diabetic patients. In TNFα-stimulated primary human retinal microvascular endothelial cells, total levels of epoxyeicosatrienoic acids (EETs), but not epoxydocosapentaenoic acids (EDPs), were significantly decreased. Exogenous addition of 11,12-EET or 19,20-EDP when combined with 12-(3-adamantane-1-yl-ureido)-dodecanoic acid (AUDA), an inhibitor of epoxide hydrolysis, inhibited VCAM-1 and ICAM-1 expression and protein levels; conversely the diol product of 19,20-EDP hydrolysis, 19,20-DHDP, induced VCAM1 and ICAM1 expression. 11,12-EET and 19,20-EDP also inhibited leukocyte adherence to human retinal microvascular endothelial cell monolayers and leukostasis in an acute mouse model of retinal inflammation. Our results indicate that this inhibition may be mediated through an indirect effect on NFκB activation. This is the first study demonstrating a direct comparison of EET and EDP on vascular inflammatory endpoints, and we have confirmed a comparable efficacy from each isomer, suggesting a similar mechanism of action. Taken together, these data establish that epoxygenated fatty acid elevation will inhibit early pathology related to TNFα-induced inflammation in retinal vascular diseases. PMID:27966642

  15. Inhibiting Intuitive Thinking in Mathematics Education

    ERIC Educational Resources Information Center

    Thomas, Michael O. J.

    2015-01-01

    The papers in this issue describe recent collaborative research into the role of inhibition of intuitive thinking in mathematics education. This commentary reflects on this research from a mathematics education perspective and draws attention to some of the challenges that arise in collaboration between research fields with different cultures,…

  16. Hemagglutinin inhibition assay with swine sera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hemagglutination is based on the ability of certain viruses to agglutinate red blood cells (RBC) of certain animal species by formation of cross-linking lattices between RBC. Antibodies that have the ability to inhibit the hemagglutination property of influenza A viruses are generally thought to pro...

  17. Salinomycin, a polyether ionophoric antibiotic, inhibits adipogenesis

    SciTech Connect

    Szkudlarek-Mikho, Maria; Saunders, Rudel A.; Yap, Sook Fan; Ngeow, Yun Fong; Chin, Khew-Voon

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Salinomycin inhibits preadipocyte differentiation into adipocytes. Black-Right-Pointing-Pointer Salinomycin inhibits transcriptional regulation of adipogenesis. Black-Right-Pointing-Pointer Pharmacological effects of salinomycin suggest toxicity in cancer therapy. -- Abstract: The polyether ionophoric antibiotics including monensin, salinomycin, and narasin, are widely used in veterinary medicine and as food additives and growth promoters in animal husbandry including poultry farming. Their effects on human health, however, are not fully understood. Recent studies showed that salinomycin is a cancer stem cell inhibitor. Since poultry consumption has risen sharply in the last three decades, we asked whether the consumption of meat tainted with growth promoting antibiotics might have effects on adipose cells. We showed in this report that the ionophoric antibiotics inhibit the differentiation of preadipocytes into adipocytes. The block of differentiation is not due to the induction of apoptosis nor the inhibition of cell proliferation. In addition, salinomycin also suppresses the transcriptional activity of the CCAAT/enhancer binding proteins and the peroxisome proliferator-activated receptor {gamma}. These results suggest that the ionophoric antibiotics can be exploited as novel anti-obesity therapeutics and as pharmacological probes for the study of adipose biology. Further, the pharmacological effects of salinomycin could be a harbinger of its toxicity on the adipose tissue and other susceptible target cells in cancer therapy.

  18. Factors Inhibiting Hispanic Parents' School Involvement

    ERIC Educational Resources Information Center

    Smith, Jay; Stern, Kenneth; Shatrova, Zhanna

    2008-01-01

    Factors inhibiting Hispanic parental involvement in non-metropolitan area schools were studied. With the mandates of No Child Left Behind intensifying the need to improve the academic achievement of all at-risk groups of students in American schools, and with the relatively new phenomenon of large numbers of Hispanics settling in non-metropolitan…

  19. The Mechanism Underlying Inhibition of Saccadic Return

    ERIC Educational Resources Information Center

    Ludwig, Casimir J. H.; Farrell, Simon; Ellis, Lucy A.; Gilchrist, Iain D.

    2009-01-01

    Human observers take longer to re-direct gaze to a previously fixated location. Although there has been some exploration of the characteristics of inhibition of saccadic return (ISR), the exact mechanisms by which ISR operates are currently unknown. In the framework of accumulation models of response times, in which evidence is integrated over…

  20. Temporal Preparation, Response Inhibition and Impulsivity

    ERIC Educational Resources Information Center

    Correa, Angel; Trivino, Monica; Perez-Duenas, Carolina; Acosta, Alberto; Lupianez, Juan

    2010-01-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a…

  1. Motivational Influences on Response Inhibition Measures

    ERIC Educational Resources Information Center

    Leotti, Lauren A.; Wager, Tor D.

    2010-01-01

    Psychological research has placed great emphasis on inhibitory control due to its integral role in normal cognition and clinical disorders. The stop-signal task and associated measure--stop-signal reaction time (SSRT)--provides a well-established paradigm for measuring response inhibition. However, motivational influences on stop-signal…

  2. Resveratrol inhibits polyphosphoinositide metabolism in activated platelets.

    PubMed

    Olas, Beata; Wachowicz, Barbara; Holmsen, Holm; Fukami, Miriam H

    2005-08-15

    The effects of resveratrol (trans-3,4',5-trihydroxystilbene) on activation responses and the polyphosphoinositide metabolism in human blood platelets have been studied. Resveratrol partially inhibited secretory responses (liberation of dense granule nucleotides and lysosomal acid hydrolases), microparticle formation and protein phosphorylations induced by thrombin. The effects of resveratrol on phosphoinositide metabolites, phosphatidate (PtdOH), phosphatidylinositol (PtdIns), phosphatidylinositol-4-phosphate (PtdIns-4(5)-P), phosphatidylinositol 4,5-bisphosphate (PtdIns-4,5-P2), phosphatidylinositol-3,4-bisphosphate (PtdIns-3,4-P2) and phosphatidylinositol-3,4,5-trisphosphate (PtdIns-3,4,5-P3) were monitored in blood platelets prelabelled with [32P]Pi. Resveratrol not only inhibited the marked increase in levels of PtdOH in platelets activated by thrombin (0.1 U/ml) but it decreased the steady state levels of the other polyphosphoinositide metabolites. The distribution of 32P in phosphoinositides in activated platelets was consistent with inhibition of CDP-DAG inositol transferase and a weak inhibition of PtdIns-4(5)-P kinase. These observations show that resveratrol has a profound effect on phospholipids, particularly on polyphosphoinositide metabolism, and may decrease the amount of PtdIns-4,5-P2 available for signalling in these cells.

  3. Temporal preparation, response inhibition and impulsivity.

    PubMed

    Correa, Angel; Triviño, Mónica; Pérez-Dueñas, Carolina; Acosta, Alberto; Lupiáñez, Juan

    2010-08-01

    Temporal preparation and impulsivity involve overlapping neural structures (prefrontal cortex) and cognitive functions (response inhibition and time perception), however, their interrelations had not been investigated. We studied such interrelations by comparing the performance of groups with low vs. high non-clinical trait impulsivity during a temporal preparation go no-go task. This task measured, in less than 10 min, how response inhibition was influenced both by temporal orienting of attention (guided by predictive temporal cues) and by sequential effects (produced by repetition/alternation of the duration of preparatory intervals in consecutive trials). The results showed that sequential effects produced dissociable patterns of temporal preparation as a function of impulsivity. Sequential effects facilitated both response speed (reaction times - RTs - to the go condition) and response inhibition (false alarms to the no-go condition) selectively in the low impulsivity group. In the high impulsivity group, in contrast, sequential effects only improved RTs but not response inhibition. We concluded that both excitatory and inhibitory processing may be enhanced concurrently by sequential effects, which enables the temporal preparation of fast and controlled responses. Impulsivity could hence be related to less efficient temporal preparation of that inhibitory processing.

  4. Illustrating Enzyme Inhibition Using Gibbs Energy Profiles

    ERIC Educational Resources Information Center

    Bearne, Stephen L.

    2012-01-01

    Gibbs energy profiles have great utility as teaching and learning tools because they present students with a visual representation of the energy changes that occur during enzyme catalysis. Unfortunately, most textbooks divorce discussions of traditional kinetic topics, such as enzyme inhibition, from discussions of these same topics in terms of…

  5. Neprilysin inhibition in chronic kidney disease

    PubMed Central

    Judge, Parminder; Haynes, Richard; Landray, Martin J.; Baigent, Colin

    2015-01-01

    Despite current practice, patients with chronic kidney disease (CKD) are at increased risk of progression to end-stage renal disease and cardiovascular events. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD. NEPi enhances the activity of natriuretic peptide systems leading to natriuresis, diuresis and inhibition of the renin–angiotensin system (RAS), which could act as a potentially beneficial counter-regulatory system in states of RAS activation such as chronic heart failure (HF) and CKD. Early NEPi drugs were combined with angiotensin-converting enzyme inhibitors but were associated with unacceptable rates of angioedema and, therefore, withdrawn. However, one such agent (omapatrilat) showed promise of NEP/RAS inhibition in treating CKD in animal models, producing greater reductions in proteinuria, glomerulosclerosis and tubulointerstitial fibrosis compared with isolated RAS inhibition. A new class of drug called angiotensin receptor neprilysin inhibitor (ARNi) has been developed. One such drug, LCZ696, has shown substantial benefits in trials in hypertension and HF. In CKD, HF is common due to a range of mechanisms including hypertension and structural heart disease (including left ventricular hypertrophy), suggesting that ARNi could benefit patients with CKD by both retarding the progression of CKD (hence delaying the need for renal replacement therapy) and reducing the risk of cardiovascular disease. LCZ696 is now being studied in a CKD population. PMID:25140014

  6. Neprilysin inhibition in chronic kidney disease.

    PubMed

    Judge, Parminder; Haynes, Richard; Landray, Martin J; Baigent, Colin

    2015-05-01

    Despite current practice, patients with chronic kidney disease (CKD) are at increased risk of progression to end-stage renal disease and cardiovascular events. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD. NEPi enhances the activity of natriuretic peptide systems leading to natriuresis, diuresis and inhibition of the renin-angiotensin system (RAS), which could act as a potentially beneficial counter-regulatory system in states of RAS activation such as chronic heart failure (HF) and CKD. Early NEPi drugs were combined with angiotensin-converting enzyme inhibitors but were associated with unacceptable rates of angioedema and, therefore, withdrawn. However, one such agent (omapatrilat) showed promise of NEP/RAS inhibition in treating CKD in animal models, producing greater reductions in proteinuria, glomerulosclerosis and tubulointerstitial fibrosis compared with isolated RAS inhibition. A new class of drug called angiotensin receptor neprilysin inhibitor (ARNi) has been developed. One such drug, LCZ696, has shown substantial benefits in trials in hypertension and HF. In CKD, HF is common due to a range of mechanisms including hypertension and structural heart disease (including left ventricular hypertrophy), suggesting that ARNi could benefit patients with CKD by both retarding the progression of CKD (hence delaying the need for renal replacement therapy) and reducing the risk of cardiovascular disease. LCZ696 is now being studied in a CKD population.

  7. Cyclosporine inhibits macrophage-mediated antigen presentation

    SciTech Connect

    Ziegler, H.K.; Palay, D.; Wentworth, P.; Cluff, C.

    1986-03-01

    The influence of cyclosporine on antigen-specific, macrophage-dependent T cell activation was analyzed in vitro. Murine T cell activation by antigens derived from Listeria monocytogenes was monitored by the production of interleukin-2. Pretreatment (2 hrs., 37/sup 0/C) of macrophages with cyclosporine resulted in a population of macrophages with a markedly diminished capacity to support the activation of T lymphocytes. When cyclosporine-pretreated macrophages were added to cultures of antigen and untreated T cells, the dose of cyclosporine which produced 50% inhibition was 1.5 ..mu..g/ml. Appropriate control experiments indicated that cyclosporine was indeed inhibiting at the macrophage level. The addition of interleukin-1 or indomethacin to the cultures did not alter the inhibitory effect of cyclosporine. Under conditions which produced >90% inhibition of antigen presentation, macrophage surface Ia expression was not altered, and the uptake and catabolism of radiolabelled antigen was normal. Thus, cyclosporine inhibits antigen presentation by a mechanism which appears unrelated to changes in Il-1 elaboration, prostaglandin production, Ia expression, or antigen uptake and catabolism.

  8. [The inhibition of potato tubers wound reparation].

    PubMed

    Chalenko, G I; Vasiukova, N I; Gerasimova, N G; Ozeretskovskaia, O l

    2009-01-01

    The multiple washing of the wound surface of potato tubers by water adversely affected the protective properties of wound periderm. Immune inhibitor beta-1,3-beta-1,6 glucan had a property of local effect and inhibited the process of wound healing. The pentasaccharide of xyloglucan caused necrosis of potato tuber tissue and prevented the wound reparation process.

  9. Sphingolipids inhibit vimentin-dependent cell migration.

    PubMed

    Hyder, Claire L; Kemppainen, Kati; Isoniemi, Kimmo O; Imanishi, Susumu Y; Goto, Hidemasa; Inagaki, Masaki; Fazeli, Elnaz; Eriksson, John E; Törnquist, Kid

    2015-06-01

    The sphingolipids, sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC), can induce or inhibit cellular migration. The intermediate filament protein vimentin is an inducer of migration and a marker for epithelial-mesenchymal transition. Given that keratin intermediate filaments are regulated by SPC, with consequences for cell motility, we wanted to determine whether vimentin is also regulated by sphingolipid signalling and whether it is a determinant for sphingolipid-mediated functions. In cancer cells where S1P and SPC inhibited migration, we observed that S1P and SPC induced phosphorylation of vimentin on S71, leading to a corresponding reorganization of vimentin filaments. These effects were sphingolipid-signalling-dependent, because inhibition of either the S1P2 receptor (also known as S1PR2) or its downstream effector Rho-associated kinase (ROCK, for which there are two isoforms ROCK1 and ROCK2) nullified the sphingolipid-induced effects on vimentin organization and S71 phosphorylation. Furthermore, the anti-migratory effect of S1P and SPC could be prevented by expressing S71-phosphorylation-deficient vimentin. In addition, we demonstrated, by using wild-type and vimentin-knockout mouse embryonic fibroblasts, that the sphingolipid-mediated inhibition of migration is dependent on vimentin. These results imply that this newly discovered sphingolipid-vimentin signalling axis exerts brake-and-throttle functions in the regulation of cell migration.

  10. Serum amyloid P inhibits dermal wound healing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The repair of open wounds depends on granulation tissue formation and contraction, which is primarily mediated by myofibroblasts. A subset of myofibroblasts originates from bone-marrow-derived monocytes which differentiate into fibroblast-like cells called fibrocytes. Serum amyloid P (SAP) inhibits ...

  11. Search Asymmetry, Sustained Attention, and Response Inhibition

    ERIC Educational Resources Information Center

    Stevenson, Hugh; Russell, Paul N.; Helton, William S.

    2011-01-01

    In the present experiment, we used search asymmetry to test whether the sustained attention to response task is a better measure of response inhibition or sustained attention. Participants performed feature present and feature absent target detection tasks using either a sustained attention to response task (SART; high Go low No-Go) or a…

  12. Nickel Inhibits Mitochondrial Fatty Acid Oxidation

    PubMed Central

    Uppala, Radha; McKinney, Richard W.; Brant, Kelly A.; Fabisiak, James P.; Goetzman, Eric S.

    2015-01-01

    Nickel exposure is associated with changes in cellular energy metabolism which may contribute to its carcinogenic properties. Here, we demonstrate that nickel strongly represses mitochondrial fatty acid oxidation—the pathway by which fatty acids are catabolized for energy—in both primary human lung fibroblasts and mouse embryonic fibroblasts. At the concentrations used, nickel suppresses fatty acid oxidation without globally suppressing mitochondrial function as evidenced by increased glucose oxidation to CO2. Pre-treatment with L-carnitine, previously shown to prevent nickel-induced mitochondrial dysfunction in neuroblastoma cells, did not prevent the inhibition of fatty acid oxidation. The effect of nickel on fatty acid oxidation occurred only with prolonged exposure (>5 hr), suggesting that direct inhibition of the active sites of metabolic enzymes is not the mechanism of action. Nickel is a known hypoxia-mimetic that activates hypoxia inducible factor-1α (HIF1α). Nickel-induced inhibition of fatty acid oxidation was blunted in HIF1α knockout fibroblasts, implicating HIF1α as one contributor to the mechanism. Additionally, nickel down-regulated the protein levels of the key fatty acid oxidation enzyme very long-chain acyl-CoA dehydrogenase (VLCAD) in a dose-dependent fashion. In conclusion, inhibition of fatty acid oxidation by nickel, concurrent with increased glucose metabolism, represents a form of metabolic reprogramming that may contribute to nickel-induced carcinogenesis. PMID:26051273

  13. Auditory and audiovisual inhibition of return.

    PubMed

    Spence, C; Driver, J

    1998-01-01

    Two experiments examined any inhibition-of-return (IOR) effects from auditory cues and from preceding auditory targets upon reaction times (RTs) for detecting subsequent auditory targets. Auditory RT was delayed if the preceding auditory cue was on the same side as the target, but was unaffected by the location of the auditory target from the preceding trial, suggesting that response inhibition for the cue may have produced its effects. By contrast, visual detection RT was inhibited by the ipsilateral presentation of a visual target on the preceding trial. In a third experiment, targets could be unpredictably auditory or visual, and no peripheral cues intervened. Both auditory and visual detection RTs were now delayed following an ipsilateral versus contralateral target in either modality on the preceding trial, even when eye position was monitored to ensure central fixation throughout. These data suggest that auditory target-target IOR arises only when target modality is unpredictable. They also provide the first unequivocal evidence for cross-modal IOR, since, unlike other recent studies (e.g., Reuter-Lorenz, Jha, & Rosenquist, 1996; Tassinari & Berlucchi, 1995; Tassinari & Campara, 1996), the present cross-modal effects cannot be explained in terms of response inhibition for the cue. The results are discussed in relation to neurophysiological studies and audiovisual links in saccade programming.

  14. BROMODICHLOROMETHANE INHIBITS HUMAN PLACENTAL TROPHOBLAST DIFFERENTIATION

    EPA Science Inventory

    BROMODICHLOROMETHANE INHIBITS HUMAN PLACENTAL
    TROPHOBLAST DIFFERENTIATION
    Jiangang Chen, Twanda L. Thirkill, Peter N. Lohstroh, Susan R. Bielmeier, Michael
    G. Narotsky, Deborah S. Best, Randy A. Harrison, Kala Natarajan, Rex A. Pegram,
    Bill L. Lasley, and Gordon C. Do...

  15. Inhibition of human aromatase by myosmine.

    PubMed

    Doering, Irene L; Richter, Elmar

    2009-04-01

    Myosmine, a minor tobacco alkaloid widely occurring in food products of plant and animal origin, inhibits the conversion of testosterone to estradiol by human aromatase (IC(50): 33+/-2 microM) sevenfold more potent than nicotine (IC(50): 223+/-10 microM) and may have implications for sexual hormone homoeostasis.

  16. Fullerene nanomaterials inhibit the allergic response.

    PubMed

    Ryan, John J; Bateman, Henry R; Stover, Alex; Gomez, Greg; Norton, Sarah K; Zhao, Wei; Schwartz, Lawrence B; Lenk, Robert; Kepley, Christopher L

    2007-07-01

    Fullerenes are a class of novel carbon allotropes that may have practical applications in biotechnology and medicine. Human mast cells (MC) and peripheral blood basophils are critical cells involved in the initiation and propagation of several inflammatory conditions, mainly type I hypersensitivity. We report an unanticipated role of fullerenes as a negative regulator of allergic mediator release that suppresses Ag-driven type I hypersensitivity. Human MC and peripheral blood basophils exhibited a significant inhibition of IgE dependent mediator release when preincubated with C(60) fullerenes. Protein microarray demonstrated that inhibition of mediator release involves profound reductions in the activation of signaling molecules involved in mediator release and oxidative stress. Follow-up studies demonstrated that the tyrosine phosphorylation of Syk was dramatically inhibited in Ag-challenged cells first incubated with fullerenes. In addition, fullerene preincubation significantly inhibited IgE-induced elevation in cytoplasmic reactive oxygen species levels. Furthermore, fullerenes prevented the in vivo release of histamine and drop in core body temperature in vivo using a MC-dependent model of anaphylaxis. These findings identify a new biological function for fullerenes and may represent a novel way to control MC-dependent diseases including asthma, inflammatory arthritis, heart disease, and multiple sclerosis.

  17. Behavioral Inhibition in Children with Learning Disabilities

    ERIC Educational Resources Information Center

    De Weerdt, Frauke; Desoete, Annemie; Roeyers, Herbert

    2013-01-01

    Children with reading disabilities (RD, n = 17), mathematical disabilities (MD, n = 22), combined reading and mathematical disabilities (RD + MD, n = 28) and control peers (n = 45) were tested on behavioral inhibition with a Go/no-go task in a picture, letter and digit-modality. In contrast to children without RD, children with RD made…

  18. Curcumin inhibition of angiogenesis and adipogenesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growth of new blood vessels or angiogenesis is necessary for the growth of adipose tissue. Adipokines produced by fat cells stimulate this process. Some dietary polyphenols with antiangiogenic activity may suppress adipose tissue growth not only by inhibiting angiogenesis, but also by interferin...

  19. Aqueous rust-inhibiting and lubricating compositions

    SciTech Connect

    Brandolese, E.

    1983-06-14

    Rust-inhibiting compounds, especially for aqueous systems such as tool-lubricating emulsions for machine tools and which consist of amine salts of a number of monoaminoalkylene dicarboxylic acids are disclosed. These rust-inhibitors are used in combination with water and an alkanolamine. Examples and test results are given.

  20. Inhibited interferon production after space flight

    NASA Technical Reports Server (NTRS)

    Sonnenfeld, G.; Gould, C. L.; Williams, J.; Mandel, A. D.

    1988-01-01

    Several studies have been performed in our laboratories indicating that interferon production may be impaired in rodents after space flight. Using an antiorthostatic suspension model that simulates some of the effects of microgravity seen during space flight, we have shown that interferon-alpha/beta production was inhibited. The inhibition was not due solely to the stress of suspension. The inhibited interferon production was transient, as suspended animals returned to normal caging recovered the ability to produce interferon. Antiorthostatic suspension of mice also resulted in a loss of resistance to infection with the diabetogenic strain of encephalomyocarditis virus, which correlated with the drop in interferon production. In rats flown in US Space Shuttle mission SL-3, interferon-gamma production was inhibited severely when spleen cells were challenged with concanavalin-A upon return to earth. In contrast, interleukin-3 production by these cells was normal. These results suggest that immune responses may be altered after antiorthostatic modeling or space flight, and the resistance to viral infections may be especially affected.

  1. Inhibition of cellulase by fermentation products

    SciTech Connect

    Takagi, M.

    1984-12-01

    Cellulosic materials are important resources for the production of fuels and chemicals. One of the processes designed to utilize cellulosic materials is enzymatic hydrolysis followed by fermentation to final products. It was shown that simultaneous saccharification and fermentation (SSF) is effective in the production of ethanol from cellulose. The acceleration of the rate of cellulose degradation in SSF was caused by less inhibition of cellulase by ethanol than by glucose and/or cellobiose. In order to apply the SSF method effectively to the production of substances derived from glucose by fermentation, several conditions should be satisfied. One of them is the coincidence of conditions of enzymatic hydrolysis and fermentation of hydrolyzate, such as pH and temperature. The second condition is that the inhibition of cellulase by the final product is less than that by glucose and/or cellobiose. There has been a comprehensive review and some reports on inhibition of cellulase by saccharides such as glucose, cellobiose, xylose, lactose, maltose, metals, and some chemicals such as dyes, detergents, halogenated compounds, and phenolic compounds. In this communication, the inhibition of cellulase by several substances derived by fermentation of glucose is reported. 7 references.

  2. Gold Nanoparticles Inhibit Matrix Metalloproteases without Cytotoxicity.

    PubMed

    Hashimoto, M; Sasaki, J I; Yamaguchi, S; Kawai, K; Kawakami, H; Iwasaki, Y; Imazato, S

    2015-08-01

    Nanoparticles (NPs) are currently the focus of considerable attention for dental applications; however, their biological effects have not been fully elucidated. The long-term, slow release of matrix metalloproteases (MMPs) digests collagen fibrils within resin-dentin bonds. Therefore, MMP inhibitors can prolong the durability of resin-dentin bonds. However, there have been few reports evaluating the combined effect of MMP inhibition and the cytotoxic effects of NPs for dentin bonding. The aim of this study was to evaluate MMP inhibition and cytotoxic responses to gold (AuNPs) and platinum nanoparticles (PtNPs) stabilized by polyvinylpyrrolidone (PVP) in cultured murine macrophages (RAW264) by using MMP inhibition assays, measuring cell viability and inflammatory responses (quantitative reverse transcription polymerase chain reaction [RT-qPCR]), and conducting a micromorphological analysis by fluorescence and transmission electron microscopy. Cultured RAW264 cells were exposed to metal NPs at various concentrations (1, 10, 100, and 400 µg/mL). AuNPs and PtNPs markedly inhibited MMP-8 and MMP-9 activity. Although PtNPs were cytotoxic at high concentrations (100 and 400 µg/mL), no cytotoxic effects were observed for AuNPs at any concentration. Transmission electron microscopy images showed a significant nonrandom intercellular distribution for AuNPs and PtNPs, which were mostly observed to be localized in lysosomes but not in the nucleus. RT-qPCR analysis demonstrated inflammatory responses were not induced in RAW264 cells by AuNPs or PtNPs. The cytotoxicity of nanoparticles might depend on the core metal composition and arise from a "Trojan horse" effect; thus, MMP inhibition could be attributed to the surface charge of PVP, which forms the outer coating of NPs. The negative charge of the surface coating of PVP binds to Zn(2+) from the active center of MMPs by chelate binding and results in MMP inhibition. In summary, AuNPs are attractive NPs that effectively

  3. Proliferative and toxic effects of ultraviolet light and inflammation on epidermal pigment cells

    SciTech Connect

    Nordlund, J.J.; Ackles, A.E.; Traynor, F.F.

    1981-10-01

    The ear of the mouse is useful for studying the effects of ultraviolet light on epidermal pigment cells. The quantity of light penetrating into the skin causing an inflammatory response can be assessed easily by measuring with an engineering calipers the swelling of the ear. The inflammatory response of the ear exhibits a linear relationship to the dose of light delivered. We observed that doses of shortwave ultraviolet light which are noninflammatory when repeated at daily intervals induce moderate to severe inflammation. Small doses of psoralen and prolonged exposure to UVA (PUVA) were more inflammatory than larger amounts of psoralen and short exposure to light. Doses of shortwave ultraviolet light and PUVA which produce only a minimal inflammation of the skin stimulate the proliferation of epidermal melanocytes. In contrast, PUVA in doses sufficiently large to cause a marked inflammatory reaction in the skin seems injurious to pigment cells and kills them or causes only a minimal proliferative response. The inflammatory reaction itself does not seem to stimulate or inhibit the proliferation of melanocytes. Prostaglandins A, E, and F2 alpha have no effect on the proliferation of epidermal pigment cells. In contrast, dimethyl sulfoxide (DMSO) and allergic contact dermatitis increase the numerical density of pigment cells. Steroids may block the function of the enzyme tyrosinase. Our experiments indicate that pigment cells, like many other varieties of cells, are susceptible to injury and can be killed at least by large doses of PUVA.

  4. Inhibition of lung tumorigenesis by tea.

    PubMed

    Yang, Chung S; Liao, Jie; Yang, Guang-yu; Lu, Gary

    2005-01-01

    Tea and tea constituents have been shown by different investigators to inhibit lung tumorigenesis in different animal model systems. This includes lung tumorigenesis in A/J mice induced by 4-(methylnitrosamino)-1-(3pyridyl)-1-butanone (NNK), N-nitrosodiethylamine, benzo[a]pyrene, N-nitrosomethylurea, or cisplatin. Inhibition of lung tumorigenesis has also been demonstrated in C3H mice treated with N-nitrosodiethylamine. In most of these experiments, reduction in tumor number and tumor size has been observed in the tea-treated group, and in some experiments, decreased tumor incidence has also been observed. The green tea constituent, epigallocatechin-3-gallate (EGCG), and the black tea constituent, theaflavins, have also been shown to be effective. Black tea preparations have been shown to reduce the incidence and number of spontaneously generated lung adenocarcinomas and rhabdomyosarcoma in A/J mice, as well as inhibit the progression of lung adenoma to adenocarcinoma. The mechanisms for the inhibitory action have not been well elucidated. It may be related to the antiproliferative, proapoptotic, and antiangiogenic activities of tea constituents that have been demonstrated in some experiments. These activities may be a result of the inhibition of key protein kinases involved in signal transduction and cell cycle regulation. Tea catechins, such as EGCG, have been suggested to be the effective components. However, a study suggests that caffeine is the key effective constituent for the inhibitory activity of lung tumorigenesis in Fisher 344 rats by black tea. In many of the experiments, tea consumption resulted in the reduction of body fat and body weight; these factors may also contribute to the inhibition of tumorigenesis.

  5. Cisplatin inhibits MEK1/2

    PubMed Central

    Yamamoto, Tetsu; Tsigelny, Igor F.; Götz, Andreas W.; Howell, Stephen B.

    2015-01-01

    Cisplatin (cDDP) is known to bind to the CXXC motif of proteins containing a ferrodoxin-like fold but little is known about its ability to interact with other Cu-binding proteins. MEK1/2 has recently been identified as a Cu-dependent enzyme that does not contain a CXXC motif. We found that cDDP bound to and inhibited the activity of recombinant MEK1 with an IC50 of 0.28 μM and MEK1/2 in whole cells with an IC50 of 37.4 μM. The inhibition of MEK1/2 was relieved by both Cu+1 and Cu+2 in a concentration-dependent manner. cDDP did not inhibit the upstream pathways responsible for activating MEK1/2, and did not cause an acute depletion of cellular Cu that could account for the reduction in MEK1/2 activity. cDDP was found to bind MEK1/2 in whole cells and the extent of binding was augmented by supplementary Cu and reduced by Cu chelation. Molecular modeling predicts 3 Cu and cDDP binding sites and quantum chemistry calculations indicate that cDDP would be expected to displace Cu from each of these sites. We conclude that, at clinically relevant concentrations, cDDP binds to and inhibits MEK1/2 and that both the binding and inhibitory activity are related to its interaction with Cu bound to MEK1/2. This may provide the basis for useful interactions of cDDP with other drugs that inhibit MAPK pathway signaling. PMID:26155939

  6. Antiretrovirals inhibit arginase in human microglia.

    PubMed

    Lisi, Lucia; Laudati, Emilia; Miscioscia, Teresa F; Dello Russo, Cinzia; Topai, Alessandra; Navarra, Pierluigi

    2016-01-01

    Preliminary evidence in an animal model, that is, primary cultures of rat microglia cells, suggested that some antiretroviral drugs (ARVs), namely darunavir, atazanavir, efavirenz, and nevirapine, increase NO production through a mechanism involving the inhibition of arginase (ARG) activity. This study was conceived to investigate the effects of ARVs on ARG activity in a human experimental model. We compared CHME-5 human microglial immortalized cells under basal conditions with cells exposed to either IL-4, a mix of inflammatory cytokines, or both stimuli given together. We also tested the effects of ARVs on CHME-5 cell lysates after exposure to the above stimuli. Moreover, the interaction between the ARVs and ARG was investigated via computational chemistry. We found that ARVs consistently inhibit ARG activity both in intact and lysed cells. In docking studies, darunavir and atazanavir showed similar scores compared with both l-arginine and the ARG antagonist nor-NOHA. Efavirenz and nevirapine, which are less potent in inhibiting ARG in the biochemical assay, also had lower scores. In conclusion, the present findings in a human model support the notion that ARG pathway can present a new, additional molecular target for different ARVs in HIV treatments. We found that antiretroviral drugs (ARVs) consistently inhibit arginase (ARG)-I activity both in intact and lysed cells. In docking studies, darunavir (DRV) and atazanavir (ATV) showed similar scores compared to both l-arginine and the ARG antagonist, Nω-hydroxy-nor-arginine (nor-NOHA). Efavirenz (EFV) and nevirapine (NVP), which are less potent in inhibiting ARG in the biochemical assay, also had lower scores. In conclusion, the present findings in a human model support the notion that ARG pathway can be envisioned as an additional and new molecular target of different ARVs in HIV treatments.

  7. VISUALIZATION-BASED ANALYSIS FOR A MIXED-INHIBITION BINARY PBPK MODEL: DETERMINATION OF INHIBITION MECHANISM

    EPA Science Inventory

    A physiologically-based pharmacokinetic (PBPK) model incorporating mixed enzyme inhibition was used to determine mechanism of the metabolic interactions occurring during simultaneous inhalation exposures to the organic solvents chloroform and trichloroethylene (TCE).

    V...

  8. Purinergic inhibition of glucose transport in cardiomyocytes.

    PubMed

    Fischer, Y; Becker, C; Löken, C

    1999-01-08

    ATP is known to act as an extracellular signal in many organs. In the heart, extracellular ATP modulates ionic processes and contractile function. This study describes a novel, metabolic effect of exogenous ATP in isolated rat cardiomyocytes. In these quiescent (i.e. noncontracting) cells, micromolar concentrations of ATP depressed the rate of basal, catecholamine-stimulated, or insulin-stimulated glucose transport by up to 60% (IC50 for inhibition of insulin-dependent glucose transport, 4 microM). ATP decreased the amount of glucose transporters (GLUT1 and GLUT4) in the plasma membrane, with a concomitant increase in intracellular microsomal membranes. A similar glucose transport inhibition was produced by P2 purinergic agonists with the following rank of potencies: ATP approximately ATPgammaS approximately 2-methylthio-ATP (P2Y-selective) > ADP > alpha,betameATP (P2X-selective), whereas the P1 purinoceptor agonist adenosine was ineffective. The effect of ATP was suppressed by the poorly subtype-selective P2 antagonist pyridoxal-phosphate-6-azophenyl-2', 4'-disulfonic acid but, surprisingly, not by the nonselective antagonist suramin nor by the P2Y-specific Reactive Blue 2. Glucose transport inhibition by ATP was not affected by a drastic reduction of the extracellular concentrations of calcium (down to 10(-9) M) or sodium (down to 0 mM), and it was not mimicked by a potassium-induced depolarization, indicating that purinoceptors of the P2X family (which are nonselective cation channels whose activation leads to a depolarizing sodium and calcium influx) are not involved. Inhibition was specific for the transmembrane transport of glucose because ATP did not inhibit (i) the rate of glycolysis under conditions where the transport step is no longer rate-limiting nor (ii) the rate of [1-14C]pyruvate decarboxylation. In conclusion, extracellular ATP markedly inhibits glucose transport in rat cardiomyocytes by promoting a redistribution of glucose transporters from the

  9. Spatially Reciprocal Inhibition of Inhibition within a Stimulus Selection Network in the Avian Midbrain

    PubMed Central

    Goddard, C. Alex; Mysore, Shreesh P.; Bryant, Astra S.; Huguenard, John R.; Knudsen, Eric I.

    2014-01-01

    Reciprocal inhibition between inhibitory projection neurons has been proposed as the most efficient circuit motif to achieve the flexible selection of one stimulus among competing alternatives. However, whether such a motif exists in networks that mediate selection is unclear. Here, we study the connectivity within the nucleus isthmi pars magnocellularis (Imc), a GABAergic nucleus that mediates competitive selection in the midbrain stimulus selection network. Using laser photostimulation of caged glutamate, we find that feedback inhibitory connectivity is global within the Imc. Unlike typical lateral inhibition in other circuits, intra-Imc inhibition remains functionally powerful over long distances. Anatomically, we observed long-range axonal projections and retrograde somatic labeling from focal injections of bi-directional tracers in the Imc, consistent with spatial reciprocity of intra-Imc inhibition. Together, the data indicate that spatially reciprocal inhibition of inhibition occurs throughout the Imc. Thus, the midbrain selection circuit possesses the most efficient circuit motif possible for fast, reliable, and flexible selection. PMID:24465755

  10. Lithium inhibits tumor lymphangiogenesis and metastasis through the inhibition of TGFBIp expression in cancer cells.

    PubMed

    Maeng, Yong-Sun; Lee, Rina; Lee, Boram; Choi, Seung-Il; Kim, Eung Kweon

    2016-02-09

    Metastasis is the main cause of mortality in cancer patients. Although there are many anti-cancer drugs targeting tumor growth, anti-metastatic agents are rarely developed. Angiogenesis and lymphangiogenesis are crucial for cancer progression; in particular, lymphangiogenesis is pivotal for metastasis in cancer. Here we report that lithium inhibits colon cancer metastasis by blocking lymphangiogenesis. Lithium reduces the expression of transforming growth factor-β-induced protein (TGFBIp) in colon cancer cells by inhibiting Smad3 phosphorylation via GSK3β inactivation. Moreover, lithium inhibits lymphatic endothelial cell migration, which is increased upon TGFBIp expression in tumor cells. Lithium had no significant effect on SW620 tumor growth in vitro and in vivo; however, it inhibited lymphangiogenesis in tumors. In tumor xenografts model, lithium was found to prevent metastasis to the lungs, liver, and lymph nodes by inhibiting TGFBIp-induced tumor lymphangiogenesis. Collectively, our findings demonstrate a novel role of lithium in the inhibition of colon cancer metastasis by blocking TGFBIp expression, and thereby TGFBIp-induced lymphangiogenesis, in primary tumors.

  11. Wogonin inhibits osteoclast differentiation by inhibiting NFATc1 translocation into the nucleus

    PubMed Central

    GENG, XIAOLIN; YANG, LIBIN; ZHANG, CHAO; QIN, HUA; LIANG, QIUDONG

    2015-01-01

    The aim of the present study was to identify a natural product with the ability to inhibit nuclear factor of activated T cells c1 (NFATc1) translocation from the cytoplasm to the nucleus by high-throughput screening, and to investigate the effect of the natural product upon osteoclast differentiation and its underlying mechanism. An NFATc1 antagonist redistribution assay was performed in U2OS-NFATc1 cells against a natural product library, and Wogonin was found to have the ability to inhibit the NFATc1 translocation from the cytoplasm to the nucleus. The effect of Wogonin on NFATc1 transcription activation was further determined by luciferase assay. An osteoclast differentiation assay was executed to evaluate the effect of Wogonin on osteoclast differentiation. The effect of Wogonin upon the vital genes in osteoclast differentiation was investigated using fluorescent quantitative polymerase chain reaction analysis. The natural product Wogonin significantly inhibited the translocation of NFATc1 from the cytoplasm to the nucleus and its transcriptional activation activity. Wogonin also significantly inhibited osteoclast differentiation and decreased the transcription of osteoclast-associated immunoglobulin-like receptor, tartrate-resistant acid phosphatase and calcitonin receptor. In conclusion, the natural product Wogonin inhibited osteoclast differentiation through the inhibition of NFATc1 translocation from the cytoplasm to the nucleus, and thus the downregulation of genes associated with osteoclast differentiation, which marked Wogonin as a potential treatment for osteoporosis. PMID:26622440

  12. Amiloride inhibits the initiation of Coxsackievirus and poliovirus RNA replication by inhibiting VPg uridylylation.

    PubMed

    Ogram, Sushma A; Boone, Christopher D; McKenna, Robert; Flanegan, James B

    2014-09-01

    The mechanism of amiloride inhibition of Coxsackievirus B3 (CVB3) and poliovirus type 1 (PV1) RNA replication was investigated using membrane-associated RNA replication complexes. Amiloride was shown to inhibit viral RNA replication and VPgpUpU synthesis. However, the drug had no effect on polymerase elongation activity during either (-) strand or (+) strand synthesis. These findings indicated that amiloride inhibited the initiation of RNA synthesis by inhibiting VPg uridylylation. In addition, in silico binding studies showed that amiloride docks in the VPg binding site on the back of the viral RNA polymerase, 3D(pol). Since VPg binding at this site on PV1 3D(pol) was previously shown to be required for VPg uridylylation, our results suggest that amiloride inhibits VPg binding to 3D(pol). In summary, our findings are consistent with a model in which amiloride inhibits VPgpUpU synthesis and viral RNA replication by competing with VPg for binding to 3D(pol).

  13. AMPA receptor inhibition by synaptically released zinc

    PubMed Central

    Kalappa, Bopanna I.; Anderson, Charles T.; Lippard, Stephen J.; Tzounopoulos, Thanos

    2015-01-01

    The vast amount of fast excitatory neurotransmission in the mammalian central nervous system is mediated by AMPA-subtype glutamate receptors (AMPARs). As a result, AMPAR-mediated synaptic transmission is implicated in nearly all aspects of brain development, function, and plasticity. Despite the central role of AMPARs in neurobiology, the fine-tuning of synaptic AMPA responses by endogenous modulators remains poorly understood. Here we provide evidence that endogenous zinc, released by single presynaptic action potentials, inhibits synaptic AMPA currents in the dorsal cochlear nucleus (DCN) and hippocampus. Exposure to loud sound reduces presynaptic zinc levels in the DCN and abolishes zinc inhibition, implicating zinc in experience-dependent AMPAR synaptic plasticity. Our results establish zinc as an activity-dependent, endogenous modulator of AMPARs that tunes fast excitatory neurotransmission and plasticity in glutamatergic synapses. PMID:26647187

  14. Antibiotic inhibition of group I ribozyme function.

    PubMed

    von Ahsen, U; Davies, J; Schroeder, R

    1991-09-26

    The discovery of catalytically active RNA has provided the basis for the evolutionary concept of an RNA world. It has been proposed that during evolution the functions of ancient catalytic RNA were modulated by low molecular weight effectors, related to antibiotics, present in the primordial soup. Antibiotics and RNA may have coevolved in the formation of the modern ribosome. Here we report that a set of aminoglycoside antibiotics, which are known to interact with the decoding region of the 16S ribosomal RNA of Escherichia coli, inhibit the second step of splicing of the T4 phage-derived td intron. Thus catalytic RNA seems to interact not only with a mononucleotide and an amino acid, but also with another class of biomolecules, the sugars. Splicing of other group I introns but not group II introns was inhibited. The similarity in affinity and specificity of these antibiotics for group I introns and rRNAs may result from recognition of evolutionarily conserved structures.

  15. Inhibition of the hammerhead ribozyme by neomycin.

    PubMed Central

    Stage, T K; Hertel, K J; Uhlenbeck, O C

    1995-01-01

    A series of antibiotics was tested for stimulation or inhibition of the hammerhead ribozyme cleavage reaction. Neomycin was found to be a potent inhibitor of the reaction with a Kl of 13.5 microM. Two hammerheads with well-characterized kinetics were used to determine which steps in the reaction mechanism were inhibited by neomycin. The data suggest that neomycin interacts preferentially with the enzyme-substrate complex and that this interaction leads to a reduction in the cleavage rate by stabilizing the ground state of the complex and destabilizing the transition state of the cleavage step. A comparison of neomycin with other aminoglycosides and inhibitors of hammerhead cleavage implies that the ammonium ions of neomycin are important for the antibiotic-hammerhead interaction. PMID:7489494

  16. Allosteric Inhibition of the Neuropeptidase Neurolysin*

    PubMed Central

    Hines, Christina S.; Ray, Kallol; Schmidt, Jack J.; Xiong, Fei; Feenstra, Rolf W.; Pras-Raves, Mia; de Moes, Jan Peter; Lange, Jos H. M.; Melikishvili, Manana; Fried, Michael G.; Mortenson, Paul; Charlton, Michael; Patel, Yogendra; Courtney, Stephen M.; Kruse, Chris G.; Rodgers, David W.

    2014-01-01

    Neuropeptidases specialize in the hydrolysis of the small bioactive peptides that play a variety of signaling roles in the nervous and endocrine systems. One neuropeptidase, neurolysin, helps control the levels of the dopaminergic circuit modulator neurotensin and is a member of a fold group that includes the antihypertensive target angiotensin converting enzyme. We report the discovery of a potent inhibitor that, unexpectedly, binds away from the enzyme catalytic site. The location of the bound inhibitor suggests it disrupts activity by preventing a hinge-like motion associated with substrate binding and catalysis. In support of this model, the inhibition kinetics are mixed, with both noncompetitive and competitive components, and fluorescence polarization shows directly that the inhibitor reverses a substrate-associated conformational change. This new type of inhibition may have widespread utility in targeting neuropeptidases. PMID:25378390

  17. Allosteric inhibition of the neuropeptidase neurolysin.

    PubMed

    Hines, Christina S; Ray, Kallol; Schmidt, Jack J; Xiong, Fei; Feenstra, Rolf W; Pras-Raves, Mia; de Moes, Jan Peter; Lange, Jos H M; Melikishvili, Manana; Fried, Michael G; Mortenson, Paul; Charlton, Michael; Patel, Yogendra; Courtney, Stephen M; Kruse, Chris G; Rodgers, David W

    2014-12-19

    Neuropeptidases specialize in the hydrolysis of the small bioactive peptides that play a variety of signaling roles in the nervous and endocrine systems. One neuropeptidase, neurolysin, helps control the levels of the dopaminergic circuit modulator neurotensin and is a member of a fold group that includes the antihypertensive target angiotensin converting enzyme. We report the discovery of a potent inhibitor that, unexpectedly, binds away from the enzyme catalytic site. The location of the bound inhibitor suggests it disrupts activity by preventing a hinge-like motion associated with substrate binding and catalysis. In support of this model, the inhibition kinetics are mixed, with both noncompetitive and competitive components, and fluorescence polarization shows directly that the inhibitor reverses a substrate-associated conformational change. This new type of inhibition may have widespread utility in targeting neuropeptidases.

  18. Non-Classical Inhibition of Carbonic Anhydrase

    PubMed Central

    Lomelino, Carrie L.; Supuran, Claudiu T.; McKenna, Robert

    2016-01-01

    Specific isoforms from the carbonic anhydrase (CA) family of zinc metalloenzymes have been associated with a variety of diseases. Isoform-specific carbonic anhydrase inhibitors (CAIs) are therefore a major focus of attention for specific disease treatments. Classical CAIs, primarily sulfonamide-based compounds and their bioisosteres, are examined as antiglaucoma, antiepileptic, antiobesity, antineuropathic pain and anticancer compounds. However, many sulfonamide compounds inhibit all CA isoforms nonspecifically, diluting drug effectiveness and causing undesired side effects due to off-target inhibition. In addition, a small but significant percentage of the general population cannot be treated with sulfonamide-based compounds due to a sulfa allergy. Therefore, CAIs must be developed that are not only isoform specific, but also non-classical, i.e. not based on sulfonamides, sulfamates, or sulfamides. This review covers the classes of non-classical CAIs and the recent advances in the development of isoform-specific inhibitors based on phenols, polyamines, coumarins and their derivatives. PMID:27438828

  19. Inhibition Controls Asynchronous States of Neuronal Networks

    PubMed Central

    Treviño, Mario

    2016-01-01

    Computations in cortical circuits require action potentials from excitatory and inhibitory neurons. In this mini-review, I first provide a quick overview of findings that indicate that GABAergic neurons play a fundamental role in coordinating spikes and generating synchronized network activity. Next, I argue that these observations helped popularize the notion that network oscillations require a high degree of spike correlations among interneurons which, in turn, produce synchronous inhibition of the local microcircuit. The aim of this text is to discuss some recent experimental and computational findings that support a complementary view: one in which interneurons participate actively in producing asynchronous states in cortical networks. This requires a proper mixture of shared excitation and inhibition leading to asynchronous activity between neighboring cells. Such contribution from interneurons would be extremely important because it would tend to reduce the spike correlation between neighboring pyramidal cells, a drop in redundancy that could enhance the information-processing capacity of neural networks. PMID:27274721

  20. Dimethyl sulfoxide inhibits bioactivation of sulindac.

    PubMed

    Swanson, B N; Boppana, V K; Vlasses, P H; Rotmensch, H H; Ferguson, R K

    1983-07-01

    Sulindac, a nonsteroidal anti-inflammatory agent, is converted to a bioactive sulfide metabolite via reversible reduction of its sulfoxide moiety. To test whether DMSO can inhibit conversion of sulindac to its active form, eight healthy men received, in a randomized, crossover manner, 400 mg of sulindac, orally, either alone or 60 min after an oral dose of DMSO (30 ml, 70% solution). After the drug combination, mean plasma concentrations of the sulfide metabolite were significantly lower than in controls at 1.5, 2, 3, 4, and 8 hr after sulindac administration. The mean area under the plasma sulfide concentration-time curve for 0 to 12 hr was 30% (range 7% to 56%) lower after DMSO treatment. This study suggests that DMSO can inhibit metabolism of other sulfoxides in man and may antagonize the therapeutic efficacy of sulindac.

  1. Kinetics of ethanol inhibition in alcohol fermentation.

    PubMed

    Luong, J H

    1985-03-01

    The inhibitory effect of ethanol on yeast growth and fermentation has been studied for the strain Saccharomyces cerevisiae ATCC No. 4126 under anaerobic batch conditions. The results obtained reveal that there is no striking difference between the response of growth and ethanol fermentation. Two kinetic models are also proposed to describe the kinetic pattern of ethanol inhibition on the specific rates of growth and ethanol fermentation: microi/micro0 = 1 - (P/Pm)alpha (for growth) nui/nu0 = 1 - (P/P'm)beta (for ethanol production). The maximum allowable ethanol concentration above which cells do not grow was predicted to be 112 g/L. The ethanol-producing capability of the cells was completely inhibited at 115 g/L ethanol. The proposed models appear to accurately represent the experimental data obtained in this study and the literature data.

  2. Kinetics of ethanol inhibition in alcohol fermentation

    SciTech Connect

    Luong, J.H.T.

    1985-01-01

    The inhibitory effect of ethanol on yeast growth and fermentation has been studied for the strain Saccharo-myces cerevisiae ATCC No. 4126 under anaerobic batch conditions. The results obtained reveal that there is no striking difference between the response of growth and ethanol fermentation. Two kinetic models are also proposed to describe the kinetic pattern of ethanol inhibition on the specific rates of growth and ethanol fermentation. The maximum allowable ethanol concentration above which cells do not grow was predicted to be 112 g/L. The ethanol-producing capability of the cells was completely inhibited at 115 g/L ethanol. The proposed models appear to accurately represent the experimental data obtained in this study and the literature data.

  3. Blocking of potentiation of latent inhibition.

    PubMed

    Hall, Geoffrey; Rodriguez, Gabriel

    2011-01-01

    We present a theory of latent inhibition based on the Pearce-Hall (Pearce & Hall, 1980) model for classical conditioning. Its central features are (1) that the associability of a stimulus declines as it comes to predict its consequences and (2) that nonreinforced exposure to a stimulus engages an associative learning process that makes the stimulus an accurate predictor of its consequences (in this case, the occurrence of no event). A formalization of this theory is shown to accommodate the finding that preexposure in compound with another cue can potentiate latent inhibition to the target cue. It further predicts that preexposure to the added cue will eliminate the potentiation effect. An experiment using rats and the flavor-aversion procedure confirmed this prediction.

  4. AMPK inhibition in health and disease.

    PubMed

    Viollet, Benoit; Horman, Sandrine; Leclerc, Jocelyne; Lantier, Louise; Foretz, Marc; Billaud, Marc; Giri, Shailendra; Andreelli, Fabrizio

    2010-08-01

    All living organisms depend on dynamic mechanisms that repeatedly reassess the status of amassed energy, in order to adapt energy supply to demand. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals managing energy balance. Control of AMPK activity involves allosteric AMP and ATP regulation, auto-inhibitory features and phosphorylation of its catalytic (alpha) and regulatory (beta and gamma) subunits. AMPK has a prominent role not only as a peripheral sensor but also in the central nervous system as a multifunctional metabolic regulator. AMPK represents an ideal second messenger for reporting cellular energy state. For this reason, activated AMPK acts as a protective response to energy stress in numerous systems. However, AMPK inhibition also actively participates in the control of whole body energy homeostasis. In this review, we discuss recent findings that support the role and function of AMPK inhibition under physiological and pathological states.

  5. Methamphetamine inhibits antigen processing, presentation, and phagocytosis.

    PubMed

    Tallóczy, Zsolt; Martinez, Jose; Joset, Danielle; Ray, Yonaton; Gácser, Attila; Toussi, Sima; Mizushima, Noboru; Nosanchuk, Joshua D; Nosanchuk, Josh; Goldstein, Harris; Loike, John; Sulzer, David; Santambrogio, Laura

    2008-02-08

    Methamphetamine (Meth) is abused by over 35 million people worldwide. Chronic Meth abuse may be particularly devastating in individuals who engage in unprotected sex with multiple partners because it is associated with a 2-fold higher risk for obtaining HIV and associated secondary infections. We report the first specific evidence that Meth at pharmacological concentrations exerts a direct immunosuppressive effect on dendritic cells and macrophages. As a weak base, Meth collapses the pH gradient across acidic organelles, including lysosomes and associated autophagic organelles. This in turn inhibits receptor-mediated phagocytosis of antibody-coated particles, MHC class II antigen processing by the endosomal-lysosomal pathway, and antigen presentation to splenic T cells by dendritic cells. More importantly Meth facilitates intracellular replication and inhibits intracellular killing of Candida albicans and Cryptococcus neoformans, two major AIDS-related pathogens. Meth exerts previously unreported direct immunosuppressive effects that contribute to increased risk of infection and exacerbate AIDS pathology.

  6. Inhibition of Plasmodium Liver Infection by Ivermectin

    PubMed Central

    Mendes, António M.; Albuquerque, Inês S.; Machado, Marta; Pissarra, Joana; Meireles, Patrícia

    2016-01-01

    ABSTRACT Avermectins are powerful endectocides with an established potential to reduce the incidence of vector-borne diseases. Here, we show that several avermectins inhibit the hepatic stage of Plasmodium infection in vitro. Notably, ivermectin potently inhibits liver infection in vivo by impairing parasite development inside hepatocytes. This impairment has a clear impact on the ensuing blood stage parasitemia, reducing disease severity and enhancing host survival. Ivermectin has been proposed as a tool to control malaria transmission because of its effects on the mosquito vector. Our study extends the effect of ivermectin to the early stages of mammalian host infection and supports the inclusion of this multipurpose drug in malaria control strategies. PMID:27895022

  7. The inhibition of tyrosinase by pyridinones.

    PubMed Central

    Hider, R C; Lerch, K

    1989-01-01

    3-Hydroxypyridine-4-ones have potential as orally active chelators of iron(III) and therefore may find application in the treatment of thalassaemia. An undesirable feature of these molecules is that they inhibit tyrosinase. We have established that alkyl substitution at position 2 in the aromatic ring minimizes interaction with tyrosinase and does so without appreciably influencing the affinity for iron(III). PMID:2493243

  8. Henri Laborit and the inhibition of action.

    PubMed

    Kunz, Edward

    2014-03-01

    Henri Laborit was one of the founders of modern neuropsychopharmacology, having discovered, or participated in, the discovery of chlorpromazine, gamma-OH, clomethiazole, and minaprine. He also put forward a theory regarding the necessity of counteracting the negative consequences of defense mechanisms during anesthesia or behavioral inhibition. The scope of his work covers neurophysiology, pharmacology, psychiatry, and psychosomatics. His independence of spirit meant that most of his research was not done within university settings.

  9. Henri Laborit and the inhibition of action

    PubMed Central

    Kunz, Edward

    2014-01-01

    Henri Laborit was one of the founders of modern neuropsychopharmacology, having discovered, or participated in, the discovery of chlorpromazine, gamma-OH, clomethiazole, and minaprine. He also put forward a theory regarding the necessity of counteracting the negative consequences of defense mechanisms during anesthesia or behavioral inhibition. The scope of his work covers neurophysiology, pharmacology, psychiatry, and psychosomatics. His independence of spirit meant that most of his research was not done within university settings. PMID:24733976

  10. Obestatin acts in brain to inhibit thirst.

    PubMed

    Samson, Willis K; White, Meghan M; Price, Christopher; Ferguson, Alastair V

    2007-01-01

    Derived from the same prohormone, obestatin has been reported to exert effects on food intake that oppose those of ghrelin. The obestatin receptor GPR39 is present in brain and pituitary gland. Since the gene encoding those two peptides is expressed also in those tissues, we examined further the possible actions of obestatin in vivo and in vitro. Intracerebroventricular administration of obestatin inhibited water drinking in ad libitum-fed and -watered rats, and in food-and water-deprived animals. The effects on water drinking preceded and were more pronounced than any effect on food intake, and did not appear to be the result of altered locomotor/behavioral activity. In addition, obestatin inhibited ANG II-induced water drinking in animals provided free access to water and food. Current-clamp recordings from cultured, subfornical organ neurons revealed significant effects of the peptide on membrane potential, suggesting this as a potential site of action. In pituitary cell cultures, log molar concentrations of obestatin ranging from 1.0 pM to 100 nM failed to alter basal growth hormone (GH) secretion. In addition, 100 nM obestatin failed to interfere with the stimulation of GH secretion by GH-releasing hormone or ghrelin and did not alter the inhibition by somatostatin in vitro. We conclude that obestatin does not act in pituitary gland to regulate GH secretion but may act in brain to alter thirst mechanisms. Importantly, in rats the effects of obestatin on food intake may be secondary to an action of the peptide to inhibit water drinking.

  11. Inhibition of Alkaline Phosphatase by Several Diuretics

    DTIC Science & Technology

    1980-01-01

    August 20th, 1979) . . Summary , . Acetazolamide, furosemide, ethacrynic acid and chlorothiazide, diuretics of considerable structural diversity, inhibit...Ki is calculated to be 8.4, 7.0, 2.8 and 0.1 mmol/l for acetazolamide, furosemide, ethacrynic acid and chlorothiazide, respectively. Chlorothiazide...is a much more potent inhibitor of alkaline phos- phatase than the other three diuretics. The combination of ethacrynic acid and cysteine, itself an

  12. Inhibiting the Function of an Enzyme

    SciTech Connect

    2015-06-17

    In order to stop bacteria from reproducing and causing a disease like tuberculosis, researchers must first block its enzymes' ability to bind with certain molecules. A research team from Brandeis University worked with the Advanced Protein Characterization Facility at Argonne National Laboratory to define 13 different bacterial structures and uncover the mechanism by which their enzymes form and break bonds with molecules. This animation depicts how an enzyme may be inhibited using this knowledge.

  13. An Activation Threshold Model for Response Inhibition

    PubMed Central

    MacDonald, Hayley J.; McMorland, Angus J. C.; Stinear, Cathy M.; Coxon, James P.; Byblow, Winston D.

    2017-01-01

    Reactive response inhibition (RI) is the cancellation of a prepared response when it is no longer appropriate. Selectivity of RI can be examined by cueing the cancellation of one component of a prepared multi-component response. This substantially delays execution of other components. There is debate regarding whether this response delay is due to a selective neural mechanism. Here we propose a computational activation threshold model (ATM) and test it against a classical “horse-race” model using behavioural and neurophysiological data from partial RI experiments. The models comprise both facilitatory and inhibitory processes that compete upstream of motor output regions. Summary statistics (means and standard deviations) of predicted muscular and neurophysiological data were fit in both models to equivalent experimental measures by minimizing a Pearson Chi-square statistic. The ATM best captured behavioural and neurophysiological dynamics of partial RI. The ATM demonstrated that the observed modulation of corticomotor excitability during partial RI can be explained by nonselective inhibition of the prepared response. The inhibition raised the activation threshold to a level that could not be reached by the original response. This was necessarily followed by an additional phase of facilitation representing a secondary activation process in order to reach the new inhibition threshold and initiate the executed component of the response. The ATM offers a mechanistic description of the neural events underlying RI, in which partial movement cancellation results from a nonselective inhibitory event followed by subsequent initiation of a new response. The ATM provides a framework for considering and exploring the neuroanatomical constraints that underlie RI. PMID:28085907

  14. Inhibition of aromatase activity by flavonoids.

    PubMed

    Jeong, H J; Shin, Y G; Kim, I H; Pezzuto, J M

    1999-06-01

    In searching for potent cancer chemopreventive agents from synthetic or natural products, 28 randomly selected flavonoids were screened for inhibitory effects against partially purified aromatase prepared from human placenta. Over 50% of the flavonoids significantly inhibited aromatase activity, with greatest activity being demonstrated with apigenin (IC50: 0.9 microg/mL), chrysin (IC50: 1.1 microg/mL), and hesperetin (IC50: 1.0 microg/mL).

  15. Alpha-1-antitrypsin inhibits nitric oxide production.

    PubMed

    Chan, Edward D; Pott, Gregory B; Silkoff, Philip E; Ralston, Annemarie H; Bryan, Courtney L; Shapiro, Leland

    2012-12-01

    NO is an endogenously produced gas that regulates inflammation, vascular tone, neurotransmission, and immunity. NO production can be increased by exposing cells to several endogenous and exogenous proinflammatory mediators, including IFN-γ, TNF-α, IL-1β, and LPS. As AAT has been shown to inhibit cell activation and suppress cytokine production associated with proinflammatory stimulation, we examined AAT for NO-suppressive function. In RAW 264.7 murine macrophagic cells, physiological AAT concentrations significantly inhibited combined LPS- and IFN-γ-induced NO synthesis, and NO synthesis inhibition was associated with decreased expression of iNOS, suppressed NF-κB activation, and reduced translocation of extracellular AAT into the interior of RAW 264.7 cells. CE-2072, a synthetic inhibitor of serine proteases, also suppressed NO production, iNOS expression, and NF-κB activation. However, AAT did not alter activation of intracellular MAPKs. In subjects with genetic AAT deficiency, exhaled NO was increased significantly compared with exhaled NO in healthy controls. These in vitro and in vivo studies suggest that AAT is an endogenous inhibitor of NO production. Administering AAT or AAT-like molecules may have use as a treatment for diseases associated with excessive NO production.

  16. ROCK inhibition prevents early mouse embryo development.

    PubMed

    Duan, Xing; Chen, Kun-Lin; Zhang, Yu; Cui, Xiang-Shun; Kim, Nam-Hyung; Sun, Shao-Chen

    2014-08-01

    ROCK is a Rho-GTPase effector that is important for actin assembly and is involved in various cellular functions, including cell contraction, migration, motility, and tumor cell invasion. In this study, we investigated ROCK expression and function during early mouse embryo development. Inhibiting ROCK by Y-27632 treatment at the zygote stage resulted in first cleavage failure, and most embryos failed to develop to the 8-cell stage. When adding Y-27632 at the 8-cell stage, embryos failed to undergo compaction and could not develop into blastocysts. In addition, fluorescence staining intensity analysis indicated that actin expression at blastomere membranes was significantly reduced. After ROCK inhibition, two or more nuclei were observed in a cell, which indicated possible cytokinesis failure. Moreover, after ROCK inhibition with Y-27632, the phosphorylation levels of LIMK1/2, a downstream molecule of ROCK, were decreased at blastomere membranes. Thus, our results showed conserved roles for ROCK in this mammalian embryo model and indicated that a ROCK-LIMK1/2-actin pathway might regulate cleavage and blastocyst formation during early mouse embryo development.

  17. Motor cortex inhibition induced by acoustic stimulation.

    PubMed

    Kühn, Andrea A; Sharott, Andrew; Trottenberg, Thomas; Kupsch, Andreas; Brown, Peter

    2004-09-01

    The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following acoustic stimulation occurs at the level of the motor cortex through reticulo-cortical projections or subcortically, perhaps through reticulo-spinal projections. We compared the influence of acoustic stimulation on motor effects elicited by TMS over motor cortical areas to those evoked with subcortical electrical stimulation (SES) through depth electrodes in five patients treated with deep brain stimulation for Parkinson's disease. SES bypasses the motor cortex, demonstrating any interaction with acoustic stimuli at the subcortical level. EMG was recorded from the contralateral biceps brachii muscle. Acoustic stimulation was delivered binaurally through headphones and used as a conditioning stimulus at an interstimulus interval of 50 ms. When TMS was used as the test stimulus, the area and amplitude of the conditioned motor response was significantly inhibited (area: 57.5+/-12.9%, amplitude: 47.9+/-7.4%, as percentage of unconditioned response) whereas facilitation occurred with SES (area: 110.1+/-4.3%, amplitude: 116.9+/-6.9%). We conclude that a startle-evoked activation of reticulo-cortical projections transiently inhibits the motor cortex.

  18. Pharmacological Inhibition of Feline Immunodeficiency Virus (FIV)

    PubMed Central

    Mohammadi, Hakimeh; Bienzle, Dorothee

    2012-01-01

    Feline immunodeficiency virus (FIV) is a member of the retroviridae family of viruses and causes an acquired immunodeficiency syndrome (AIDS) in domestic and non-domestic cats worldwide. Genome organization of FIV and clinical characteristics of the disease caused by the virus are similar to those of human immunodeficiency virus (HIV). Both viruses infect T lymphocytes, monocytes and macrophages, and their replication cycle in infected cells is analogous. Due to marked similarity in genomic organization, virus structure, virus replication and disease pathogenesis of FIV and HIV, infection of cats with FIV is a useful tool to study and develop novel drugs and vaccines for HIV. Anti-retroviral drugs studied extensively in HIV infection have targeted different steps of the virus replication cycle: (1) inhibition of virus entry into susceptible cells at the level of attachment to host cell surface receptors and co-receptors; (2) inhibition of fusion of the virus membrane with the cell membrane; (3) blockade of reverse transcription of viral genomic RNA; (4) interruption of nuclear translocation and viral DNA integration into host genomes; (5) prevention of viral transcript processing and nuclear export; and (6) inhibition of virion assembly and maturation. Despite much success of anti-retroviral therapy slowing disease progression in people, similar therapy has not been thoroughly investigated in cats. In this article we review current pharmacological approaches and novel targets for anti-lentiviral therapy, and critically assess potentially suitable applications against FIV infection in cats. PMID:22754645

  19. Inhibition of fibroblast proliferation by Actinobacillus actinomycetemcomitans.

    PubMed Central

    Shenker, B J; Kushner, M E; Tsai, C C

    1982-01-01

    We have examined soluble sonic extracts of Actinobacillus actinomycetemcomitans for their ability to alter human and murine fibroblast proliferation. We found that extracts of all A. actinomycetemcomitans strains examined (both leukotoxic and nonleukotoxic) caused a dose-dependent inhibition of both murine and human fibroblast proliferation as assessed by DNA synthesis ([3H]thymidine incorporation). Addition of sonic extract simultaneously with [3H]thymidine had no effect on incorporation, indicating that suppression was not due to the presence of excessive amounts of cold thymidine. Inhibition of DNA synthesis was also paralleled by decreased RNA synthesis ([3H]uridine incorporation) and by a decrease in cell growth as assessed by direct cell counts; there was no effect on cell viability. The suppressive factor(s) is heat labile; preliminary purification and characterization studies indicate that it is a distinct and separate moiety from other A. actinomycetemcomitans mediators previously reported, including leukotoxin, immune suppressive factor, and endotoxin. Although it is not clear how A. actinomycetemcomitans acts to cause disease, we propose that one aspect of the pathogenicity of this organism rests in its ability to inhibit fibroblast growth, which in turn could contribute to the collagen loss associated with certain forms of periodontal disease, in particular juvenile periodontitis. PMID:7152684

  20. Gabapentin inhibits central sensitization during migraine.

    PubMed

    Zhang, Yanbo; Shao, Guo; Zhang, Wei; Li, Sijie; Niu, Jingzhong; Hu, Dongmei; Yang, Mingfeng; Ji, Xunming

    2013-11-15

    Peripheral and central sensitizations are phenomena that occur during migraine. The role of pentin, a migraine preventive drug, on central sensitization remains unclear. In this study, a rat model of migraine was established by electrical stimulation of the trigeminal ganglion, and the an-imals were given intragastric gabapentin. Changes in amino acid content in the cerebrospinal fluid and protein kinase C membrane translocation in the spinal trigeminal nucleus were examined to clarify the mechanisms underlying the efficacy of gabapentin in the treatment of central sensitization during migraine. Electrophysiology, liquid chromatography-mass spectrometry and western blot analysis results revealed that gabapentin reduces neuronal excitability in the spinal nucleus in the trigeminal nerve, decreases excitatory amino acid content and inhibits the activation of protein ki-nase C. This provides evidence that excitatory amino acids and protein kinase C are involved in the formation and maintenance of central sensitization during migraine. Gabapentin inhibits migraine by reducing excitatory amino acid content in the cerebrospinal fluid and inhibiting protein kinase C ac-tivation.

  1. Menaquinone Analogs Inhibit Growth of Bacterial Pathogens

    PubMed Central

    Merriman, Joseph A.; Salgado-Pabón, Wilmara; Mueller, Elizabeth A.; Spaulding, Adam R.; Vu, Bao G.; Chuang-Smith, Olivia N.; Kohler, Petra L.; Kirby, John R.

    2013-01-01

    Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents. PMID:23959313

  2. Menaquinone analogs inhibit growth of bacterial pathogens.

    PubMed

    Schlievert, Patrick M; Merriman, Joseph A; Salgado-Pabón, Wilmara; Mueller, Elizabeth A; Spaulding, Adam R; Vu, Bao G; Chuang-Smith, Olivia N; Kohler, Petra L; Kirby, John R

    2013-11-01

    Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents.

  3. JAK INHIBITION AND PROGRESSIVE KIDNEY DISEASE

    PubMed Central

    Brosius, Frank C.; He, John Cijiang

    2015-01-01

    Purpose of review To review the role of JAK-STAT signaling in the progression of chronic kidney diseases. Recent findings The JAK-STAT pathway transmits signals from extracellular ligands, including many cytokines and chemokines. While these responses are best characterized in lymphoid cells, they also occur in kidney cells such as podocytes, mesangial cells, and tubular cells. JAK-STAT expression and signaling abnormalities occur in humans and animal models of different chronic kidney diseases. Enhanced expression and augmented activity of JAK1, JAK2 and STAT3 promote diabetic nephropathy and their inhibition appears to reduce disease. Activation of JAK-STAT signaling in autosomal dominant polycystic kidney disease may play an important role in cyst growth. Activation of JAK-STAT signaling promotes HIV-associated nephropathy and may also participate in the tubular responses to chronic obstructive uropathy. Based on data from experimental models, inhibition of JAK-STAT signaling, via increased expression of the suppressors of cytokine signaling proteins or pharmacologic inhibition of JAK and STAT proteins, could play a therapeutic role in multiple chronic kidney diseases. Summary Activation of the JAK-STAT pathway appears to play a role in the progression of some chronic kidney diseases. More work is needed to determine the specific role the pathway plays in individual diseases. PMID:25415616

  4. Inhibition of SIRT2 suppresses hepatic fibrosis.

    PubMed

    Arteaga, Maribel; Shang, Na; Ding, Xianzhong; Yong, Sherri; Cotler, Scott J; Denning, Mitchell F; Shimamura, Takashi; Breslin, Peter; Lüscher, Bernhard; Qiu, Wei

    2016-06-01

    Liver fibrosis can progress to cirrhosis and result in serious complications of liver disease. The pathogenesis of liver fibrosis involves the activation of hepatic stellate cells (HSCs), the underlying mechanisms of which are not fully known. Emerging evidence suggests that the classic histone deacetylases play a role in liver fibrosis, but the role of another subfamily of histone deacetylases, the sirtuins, in the development of hepatic fibrosis remains unknown. In this study, we found that blocking the activity of sirtuin 2 (SIRT2) by using inhibitors or shRNAs significantly suppressed fibrogenic gene expression in HSCs. We further demonstrated that inhibition of SIRT2 results in the degradation of c-MYC, which is important for HSC activation. In addition, we discovered that inhibition of SIRT2 suppresses the phosphorylation of ERK, which is critical for the stabilization of c-MYC. Moreover, we found that Sirt2 deficiency attenuates the hepatic fibrosis induced by carbon tetrachloride (CCl4) and thioacetamide (TAA). Furthermore, we showed that SIRT2, p-ERK, and c-MYC proteins are all overexpressed in human hepatic fibrotic tissues. These data suggest a critical role for the SIRT2/ERK/c-MYC axis in promoting hepatic fibrogenesis. Inhibition of the SIRT2/ERK/c-MYC axis represents a novel strategy to prevent and to potentially treat liver fibrosis and cirrhosis.

  5. Trace element inhibition of phytase activity.

    PubMed

    Santos, T; Connolly, C; Murphy, R

    2015-02-01

    Nowadays, 70 % of global monogastric feeds contains an exogenous phytase. Phytase supplementation has enabled a more efficient utilisation of phytate phosphorous (P) and reduction of P pollution. Trace minerals, such as iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn) are essential for maintaining health and immunity as well as being involved in animal growth, production and reproduction. Exogenous sources of phytase and trace elements are regularly supplemented to monogastric diets and usually combined in a premix. However, the possibility for negative interaction between individual components within the premix is high and is often overlooked. Therefore, this initial study focused on assessing the potential in vitro interaction between inorganic and organic chelated sources of Fe, Zn, Cu and Mn with three commercially available phytase preparations. Additionally, this study has investigated if the degree of enzyme inhibition was dependent of the type of chelated sources. A highly significant relationship between phytase inhibition, trace mineral type as well as mineral source and concentration, p < 0.001 was verified. The proteinate sources of OTMs were consistently and significantly less inhibitory than the majority of the other sources, p < 0.05. This was verified for Escherichia coli and Peniophora lycii phytases for Fe and Zn, as well as for Cu with E. coli and Aspergillus niger phytases. Different chelate trace mineral sources demonstrated diversifying abilities to inhibit exogenous phytase activity.

  6. WR-2721 inhibits parathyroid adenylate cyclase

    SciTech Connect

    Weaver, M.E.; Morrissey, J.; McConkey, C. Jr.; Goldfarb, S.; Slatopolsky, E.; Martin, K.J.

    1987-02-01

    WR-2721 (S-2-(3-aminopropylamino)ethylphosphorothioic acid) is a chemoprotective and radioprotective agent that has been shown to lower serum calcium in dogs and in humans. This is secondary both to impaired release of CaS from bone and diminished secretion of parathyroid hormone (PTH) from parathyroid glands. Because cAMP plays a role in the regulation of PTH secretion and WR-2721 has been shown to lower cAMP levels in radiated mouse spleen, the authors investigated the effects of WR-2721 on cAMP production in dispersed bovine parathyroid cells. Additional, they studied the adenylate cyclase in plasma membranes from normal bovine parathyroid glands after exposure to WR-2721. With parathyroid cells incubated at 0.5 mM CaS , addition of Wr-2721 in concentrations ranging from 0.02 to 2.0 mM resulted in a progressive decrease in intracellular cAMP measured by radioimmunoassay. In plasma membranes of bovine parathyroid cells a dose-dependent decrease in adenylate cyclase activity was noted. Inhibition of the cyclase was seen over a wide range of MgS concentrations. WR-2721 inhibited both basal and NaF, Gpp(NH)(, forskolin, and pertussin toxin-stimulated adenylate cyclase. These data suggest that WR-2721 inhibits the activity of parathyroid adenylate cyclase.

  7. Hydrogen Sulfide Inhibits Plasma Renin Activity

    PubMed Central

    Lu, Ming; Liu, Yi-Hong; Goh, Hong Swen; Wang, Josh Jia Xing; Yong, Qian-Chen; Wang, Rui

    2010-01-01

    The development of renovascular hypertension depends on the release of renin from the juxtaglomerular (JG) cells, a process regulated by intracellular cAMP. Hydrogen sulfide (H2S) downregulates cAMP production in some cell types by inhibiting adenylyl cyclase, suggesting the possibility that it may modulate renin release. Here, we investigated the effect of H2S on plasma renin activity and BP in rat models of renovascular hypertension. In the two-kidney-one-clip (2K1C) model of renovascular hypertension, the H2S donor NaHS prevented and treated hypertension. Compared with vehicle, NaHS significantly attenuated the elevation in plasma renin activity and angiotensin II levels but did not affect plasma angiotensin-converting enzyme activity. Furthermore, NaHS inhibited the upregulation of renin mRNA and protein levels in the clipped kidneys of 2K1C rats. In primary cultures of renin-rich kidney cells, NaHS markedly suppressed forskolin-stimulated renin activity in the medium and the intracellular increase in cAMP. In contrast, NaHS did not affect BP or plasma renin activity in normal or one-kidney-one-clip (1K1C) rats, both of which had normal plasma renin activity. In conclusion, these results demonstrate that H2S may inhibit renin activity by decreasing the synthesis and release of renin, suggesting its potential therapeutic value for renovascular hypertension. PMID:20360313

  8. Wnt signaling inhibits CTL memory programming.

    PubMed

    Xiao, Zhengguo; Sun, Zhifeng; Smyth, Kendra; Li, Lei

    2013-12-01

    Induction of functional CTLs is one of the major goals for vaccine development and cancer therapy. Inflammatory cytokines are critical for memory CTL generation. Wnt signaling is important for CTL priming and memory formation, but its role in cytokine-driven memory CTL programming is unclear. We found that wnt signaling inhibited IL-12-driven CTL activation and memory programming. This impaired memory CTL programming was attributed to up-regulation of eomes and down-regulation of T-bet. Wnt signaling suppressed the mTOR pathway during CTL activation, which was different to its effects on other cell types. Interestingly, the impaired memory CTL programming by wnt was partially rescued by mTOR inhibitor rapamycin. In conclusion, we found that crosstalk between wnt and the IL-12 signaling inhibits T-bet and mTOR pathways and impairs memory programming which can be recovered in part by rapamycin. In addition, direct inhibition of wnt signaling during CTL activation does not affect CTL memory programming. Therefore, wnt signaling may serve as a new tool for CTL manipulation in autoimmune diseases and immune therapy for certain cancers.

  9. Phytic acid inhibits lipid peroxidation in vitro.

    PubMed

    Zajdel, Alicja; Wilczok, Adam; Węglarz, Ludmiła; Dzierżewicz, Zofia

    2013-01-01

    Phytic acid (PA) has been recognized as a potent antioxidant and inhibitor of iron-catalyzed hydroxyl radical formation under in vitro and in vivo conditions. Therefore, the aim of the present study was to investigate, with the use of HPLC/MS/MS, whether PA is capable of inhibiting linoleic acid autoxidation and Fe(II)/ascorbate-induced peroxidation, as well as Fe(II)/ascorbate-induced lipid peroxidation in human colonic epithelial cells. PA at 100 μM and 500 μM effectively inhibited the decay of linoleic acid, both in the absence and presence of Fe(II)/ascorbate. The observed inhibitory effect of PA on Fe(II)/ascorbate-induced lipid peroxidation was lower (10-20%) compared to that of autoxidation. PA did not change linoleic acid hydroperoxides concentration levels after 24 hours of Fe(II)/ascorbate-induced peroxidation. In the absence of Fe(II)/ascorbate, PA at 100 μM and 500 μM significantly suppressed decomposition of linoleic acid hydroperoxides. Moreover, PA at the tested nontoxic concentrations (100 μM and 500 μM) significantly decreased 4-hydroxyalkenal levels in Caco-2 cells which structurally and functionally resemble the small intestinal epithelium. It is concluded that PA inhibits linoleic acid oxidation and reduces the formation of 4-hydroxyalkenals. Acting as an antioxidant it may help to prevent intestinal diseases induced by oxygen radicals and lipid peroxidation products.

  10. Inhibition of granulation tissue growth by histamine.

    PubMed

    Saeki, K; Yokoyama, J; Wake, K

    1975-06-01

    Granulomas were induced in rats by subcutaneous implantation of formalin-soaked filter-paper disks. Daily subcutaneous injection of histamine at doses of two times 0.05 mg/kg and above inhibited the growth of granulation tissue as measured by a marked decrease in the dry-defatted granuloma weight and of the hydroxyproline and hexosamine content. Histological observations of granulation tissue indicated that histamine inhibited the proliferation of fibroblasts and the formation of capillaries. Inhibitory effects were also observed with the histamine releaser, sinomenine, and the histaminase inhibitor, aminoguanidine. These histamine effects seem not to be mediated by glucocorticoid release, since an effective dose level of histamine produced no change in growth or thymus weight. Prednisolone was less potent than histamine in inhibiting Prednisolone was ineffective at the dose tested. Subcutaneous injection of the H2-receptor antagonist, burimamide, blocked these histamine effects and also of sinomeinine and aminoguanidine. The H1-receptor antagonist, mepyramine, did not block these histamine effects. Burimamide alone enhanced the growth of granuloma. These results indicate that granulation-tissue growth in inflammation is affected by the inhibitory effect of endogenous histamine acting through H2-receptors.

  11. Antipneumococcal activity of neuraminidase inhibiting artocarpin.

    PubMed

    Walther, E; Richter, M; Xu, Z; Kramer, C; von Grafenstein, S; Kirchmair, J; Grienke, U; Rollinger, J M; Liedl, K R; Slevogt, H; Sauerbrei, A; Saluz, H P; Pfister, W; Schmidtke, M

    2015-05-01

    Streptococcus (S.) pneumoniae is a major cause of secondary bacterial pneumonia during influenza epidemics. Neuraminidase (NA) is a virulence factor of both pneumococci and influenza viruses. Bacterial neuraminidases (NAs) are structurally related to viral NA and susceptible to oseltamivir, an inhibitor designed to target viral NA. This prompted us to evaluate the antipneumococcal potential of two NA inhibiting natural compounds, the diarylheptanoid katsumadain A and the isoprenylated flavone artocarpin. Chemiluminescence, fluorescence-, and hemagglutination-based enzyme assays were applied to determine the inhibitory efficiency (IC(50) value) of the tested compounds towards pneumococcal NAs. The mechanism of inhibition was studied via enzyme kinetics with recombinant NanA NA. Unlike oseltamivir, which competes with the natural substrate of NA, artocarpin exhibits a mixed-type inhibition with a Ki value of 9.70 μM. Remarkably, artocarpin was the only NA inhibitor (NAI) for which an inhibitory effect on pneumococcal growth (MIC: 0.99-5.75 μM) and biofilm formation (MBIC: 1.15-2.97 μM) was observable. In addition, we discovered that the bactericidal effect of artocarpin can reduce the viability of pneumococci by a factor of >1000, without obvious harm to lung epithelial cells. This renders artocarpin a promising natural product for further investigations.

  12. Phytic Acid Inhibits Lipid Peroxidation In Vitro

    PubMed Central

    Węglarz, Ludmiła; Dzierżewicz, Zofia

    2013-01-01

    Phytic acid (PA) has been recognized as a potent antioxidant and inhibitor of iron-catalyzed hydroxyl radical formation under in vitro and in vivo conditions. Therefore, the aim of the present study was to investigate, with the use of HPLC/MS/MS, whether PA is capable of inhibiting linoleic acid autoxidation and Fe(II)/ascorbate-induced peroxidation, as well as Fe(II)/ascorbate-induced lipid peroxidation in human colonic epithelial cells. PA at 100 μM and 500 μM effectively inhibited the decay of linoleic acid, both in the absence and presence of Fe(II)/ascorbate. The observed inhibitory effect of PA on Fe(II)/ascorbate-induced lipid peroxidation was lower (10–20%) compared to that of autoxidation. PA did not change linoleic acid hydroperoxides concentration levels after 24 hours of Fe(II)/ascorbate-induced peroxidation. In the absence of Fe(II)/ascorbate, PA at 100 μM and 500 μM significantly suppressed decomposition of linoleic acid hydroperoxides. Moreover, PA at the tested nontoxic concentrations (100 μM and 500 μM) significantly decreased 4-hydroxyalkenal levels in Caco-2 cells which structurally and functionally resemble the small intestinal epithelium. It is concluded that PA inhibits linoleic acid oxidation and reduces the formation of 4-hydroxyalkenals. Acting as an antioxidant it may help to prevent intestinal diseases induced by oxygen radicals and lipid peroxidation products. PMID:24260736

  13. Inhibition of acetylcholinesterase by Tea Tree oil.

    PubMed

    Mills, Clive; Cleary, Brian J; Gilmer, John F; Walsh, John J

    2004-03-01

    Pediculosis is a widespread condition reported in schoolchildren. Treatment most commonly involves the physical removal of nits using fine-toothcombs and the chemical treatment of adult lice and eggs with topical preparations. The active constituents of these preparations frequently exert their effects through inhibition of acetylcholinesterase (AChE, EC 3.1.1.7). Increasing resistance to many preparations has led to the search for more effective treatments. Tea Tree oil, otherwise known as Melaleuca oil, has been added to several preparations as an alternative treatment of head lice infestations. In this study two major constituents of Tea Tree oil, 1,8-cineole and terpinen-4-ol, were shown to inhibit acetylcholinesterase at IC50 values (inhibitor concentrations required to give 50% inhibition) of 0.04 and 10.30 mM, respectively. Four samples of Tea Tree oil tested (Tisserand, Body Treats, Main Camp and Irish Health Culture Association Pure Undiluted) showed anticholinesterase activity at IC50 values of 0.05, 0.10, 0.08 and 0.11 microL mL(-1), respectively. The results supported the hypothesis that the insecticidal activity of Tea Tree oil was attributable, in part, to the anticholinesterase activity of Tea Tree oil.

  14. Thiomers: Inhibition of cytochrome P450 activity.

    PubMed

    Iqbal, Javed; Sakloetsakun, Duangkamon; Bernkop-Schnürch, Andreas

    2011-08-01

    The aim of the present study was to investigate the potential of different thiolated polymers (thiomers) on the catalytic activity of CYP450s on one hand and to explore new inhibitors for CYP activity on the other hand. Several thiolated polymers including poly(acrylic acid)-cysteine (PAA-cysteine), chitosan-thioglycolic acid (chitosan-TGA), and thiolated PEG-g-PEI copolymer along with brij 35, myrj 52 and the well-established CYPP450 inhibitor verapamil were screened for their CYP3A4 and CYP2A6 inhibitory activity, and their IC(50) values were determined. Both enzyme inhibition assays were performed in 96-well microtiter plates. 7-Benzyloxy-4-(trifluoromethyl)-coumarin (BFC) and 7-hydroxycoumarin (7-HC) were used as fluorescent substrates in order to determine CYP3A4 and CYP2A6 catalytic activity, respectively. All investigated compounds inhibited CYP3A4 as well as CYP2A6 activity. All tested (thiolated) polymers were found to be more potent inhibitors of CYP3A4 than of CYP2A6 catalytic activity. Apart from verapamil that is a known CYP3A4 inhibitor, brij 35 and myrj 52 were explored as potent inhibitors of CYP3A4 and CYP2A6 catalytic activity. Among the tested polymers, the rank order for CYP3A4 inhibition was PAA-cysteine (100 kDa)>brij 35>thiolated PEG-g-PEI copolymer (16 kDa)>myrj 52>PAA (100 kDa)>PAA-cysteine (450 kDa)>verapamil>PAA (450 kDa)>chitosan-TGA (150 kDa)>chitosan (150 kDa). On the other hand, the rank order of CYP2A6 inhibition was brij 35>PAA-cysteine (100kDa)>chitosan-TGA (150 kDa)>PAA (100 kDa)>thiolated PEG-g-PEI copolymer (16 kDa)>PAA-cysteine (450 kDa)>chitosan (150 kDa)>verapamil>PAA (450 kDa)>myrj 52. Thus, this study suggests that (thiolated) polymers display a promising potential to inhibit cytochrome P450s activity and might turn out to be potentially valuable tools for improving the oral bioavailability of actively secreted compounds by avoiding intestinal metabolism.

  15. Irreversible enzyme inhibition kinetics and drug-drug interactions.

    PubMed

    Mohutsky, Michael; Hall, Stephen D

    2014-01-01

    This chapter describes the types of irreversible inhibition of drug-metabolizing enzymes and the methods commonly employed to quantify the irreversible inhibition and subsequently predict the extent and time course of clinically important drug-drug interactions.

  16. Foxp3+ T cells inhibit antitumor immune memory modulated by mTOR inhibition.

    PubMed

    Wang, Yanping; Sparwasser, Tim; Figlin, Robert; Kim, Hyung L

    2014-04-15

    Inhibition of mTOR signaling enhances antitumor memory lymphocytes. However, pharmacologic mTOR inhibition also enhances regulatory T-cell (Treg) activity. To counter this effect, Treg control was added to mTOR inhibition in preclinical models. Tregs were controlled with CD4-depleting antibodies because CD4 depletion has high translational potential and already has a well-established safety profile in patients. The antitumor activity of the combination therapy was CD8 dependent and controlled growth of syngeneic tumors even when an adoptive immunotherapy was not used. Lymphocytes resulting from the combination therapy could be transferred into naïve mice to inhibit aggressive growth of lung metastases. The combination therapy enhanced CD8 memory formation as determined by memory markers and functional studies of immune recall. Removal of FoxP3-expressing T lymphocytes was the mechanism underlying immunologic memory formation following CD4 depletion. This was confirmed using transgenic DEREG (depletion of regulatory T cells) mice to specifically remove Foxp3(+) T cells. It was further confirmed with reciprocal studies where stimulation of immunologic memory because of CD4 depletion was completely neutralized by adoptively transferring tumor-specific Foxp3(+) T cells. Also contributing to tumor control, Tregs that eventually recovered following CD4 depletion were less immunosuppressive. These results provide a rationale for further study of mTOR inhibition and CD4 depletion in patients.

  17. Allosteric Partial Inhibition of Monomeric Proteases. Sulfated Coumarins Induce Regulation, not just Inhibition, of Thrombin

    PubMed Central

    Verespy III, Stephen; Mehta, Akul Y.; Afosah, Daniel; Al-Horani, Rami A.; Desai, Umesh R.

    2016-01-01

    Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated coumarins to discover two agents that display sub-maximal efficacy (~50%), high potency (<500 nM) and high selectivity for thrombin (>150-fold). Michaelis-Menten, competitive inhibition, and site-directed mutagenesis studies identified exosite 2 as the site of binding for the most potent sulfated coumarin. Stern-Volmer quenching of active site-labeled fluorophore suggested that the allosteric regulators induce intermediate structural changes in the active site as compared to those that display ~80–100% efficacy. Antithrombin inactivation of thrombin was impaired in the presence of the sulfated coumarins suggesting that allosteric partial inhibition arises from catalytic dysfunction of the active site. Overall, sulfated coumarins represent first-in-class, sub-maximal inhibitors of thrombin. The probes establish the concept of allosteric partial inhibition of soluble, monomeric proteins. This concept may lead to a new class of anticoagulants that are completely devoid of bleeding. PMID:27053426

  18. GTPase regulation: getting aRnd Rock and Rho inhibition.

    PubMed

    Chardin, Pierre

    2003-09-16

    Rnd proteins are atypical members of the Rho small G protein family that inhibit the formation of actomyosin contractile fibers via activation of RhoGAPs and inhibition of a Rho effector, the Ser/Thr kinase Rock. These mechanisms might be used to fine-tune Rho GTPase inhibition locally at sites where particular actin structures need to be made.

  19. Cellobionic acid inhibition of cellobiohydrolase I and cellobiose dehydrogenase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    End-product inhibition by cellobiose and glucose is a rate-limiting factor in cellulose hydrolysis by cellulases. While cellobiose and glucose inhibition have been extensively investigated, cellobionate inhibition has been minimally studied despite the discovery that accessory proteins such as cello...

  20. SIRT1 controls cell proliferation by regulating contact inhibition.

    PubMed

    Cho, Elizabeth H; Dai, Yan

    2016-09-16

    Contact inhibition keeps cell proliferation in check and serves as a built-in protection against cancer development by arresting cell division upon cell-cell contact. Yet the complete mechanism behind this anti-cancer process remains largely unclear. Here we present SIRT1 as a novel regulator of contact inhibition. SIRT1 performs a wide variety of functions in biological processes, but its involvement in contact inhibition has not been explored to date. We used NIH3T3 cells, which are sensitive to contact inhibition, and H460 and DU145 cancer cells, which lack contact inhibition, to investigate the relationship between SIRT1 and contact inhibition. We show that SIRT1 overexpression in NIH3T3 cells overcomes contact inhibition while SIRT1 knockdown in cancer cells restores their lost contact inhibition. Moreover, we demonstrate that p27 protein expression is controlled by SIRT1 in contact inhibition. Overall, our findings underline the critical role of SIRT1 in contact inhibition and suggest SIRT1 inhibition as a potential strategy to suppress cancer cell growth by restoring contact inhibition.

  1. Eye Blink Startle Responses in Behaviorally Inhibited and Uninhibited Children

    ERIC Educational Resources Information Center

    van Brakel, Anna M. L.; Muris, Peter; Derks, Wendy

    2006-01-01

    The present study examined the startle reflex as a physiological marker of behavioral inhibition. Participants were 7 to 12-year-old children who had been previously identified as inhibited or uninhibited as part of an ongoing longitudinal study on the role of behavioral inhibition in the development of anxiety disorders. Analysis of their scores…

  2. Interferon-γ Inhibits Ebola Virus Infection

    PubMed Central

    Rhein, Bethany A.; Powers, Linda S.; Rogers, Kai; Anantpadma, Manu; Singh, Brajesh K.; Sakurai, Yasuteru; Bair, Thomas; Miller-Hunt, Catherine; Sinn, Patrick; Davey, Robert A.

    2015-01-01

    Ebola virus outbreaks, such as the 2014 Makona epidemic in West Africa, are episodic and deadly. Filovirus antivirals are currently not clinically available. Our findings suggest interferon gamma, an FDA-approved drug, may serve as a novel and effective prophylactic or treatment option. Using mouse-adapted Ebola virus, we found that murine interferon gamma administered 24 hours before or after infection robustly protects lethally-challenged mice and reduces morbidity and serum viral titers. Furthermore, we demonstrated that interferon gamma profoundly inhibits Ebola virus infection of macrophages, an early cellular target of infection. As early as six hours following in vitro infection, Ebola virus RNA levels in interferon gamma-treated macrophages were lower than in infected, untreated cells. Addition of the protein synthesis inhibitor, cycloheximide, to interferon gamma-treated macrophages did not further reduce viral RNA levels, suggesting that interferon gamma blocks life cycle events that require protein synthesis such as virus replication. Microarray studies with interferon gamma-treated human macrophages identified more than 160 interferon-stimulated genes. Ectopic expression of a select group of these genes inhibited Ebola virus infection. These studies provide new potential avenues for antiviral targeting as these genes that have not previously appreciated to inhibit negative strand RNA viruses and specifically Ebola virus infection. As treatment of interferon gamma robustly protects mice from lethal Ebola virus infection, we propose that interferon gamma should be further evaluated for its efficacy as a prophylactic and/or therapeutic strategy against filoviruses. Use of this FDA-approved drug could rapidly be deployed during future outbreaks. PMID:26562011

  3. Ventral hippocampal neurons inhibit postprandial energy intake.

    PubMed

    Hannapel, Reilly C; Henderson, Yoko H; Nalloor, Rebecca; Vazdarjanova, Almira; Parent, Marise B

    2017-03-01

    Evidence suggests that the memory of a recently ingested meal limits subsequent intake. Given that ventral hippocampal (vHC) neurons are involved in memory and energy intake, the present experiment tested the hypothesis that vHC neurons contribute to the formation of a memory of a meal and inhibit energy intake during the postprandial period. We tested (1) whether pharmacological inactivation of vHC neurons during the period following a sucrose meal, when the memory of the meal would be undergoing consolidation, accelerates the onset of the next sucrose meal and increases intake and (2) whether sucrose intake increases vHC expression of the synaptic plasticity marker activity-regulated cytoskeletal-associated protein (Arc). Adult male Sprague-Dawley rats were trained to consume a 32% sucrose solution daily at the same time and location. On the experimental day, the rats were given intra-vHC infusions of the GABAA receptor agonist muscimol or vehicle after they finished their first sucrose meal. Compared to vehicle infusions, postmeal intra-vHC muscimol infusions decreased the latency to the next sucrose meal, increased the amount of sucrose consumed during that meal, increased the total number of sucrose meals and the total amount of sucrose ingested. In addition, rats that consumed sucrose had higher levels of Arc expression in both vHC CA1 and CA3 subfields than cage control rats. Collectively, these findings are the first to show that vHC neurons inhibit energy intake during the postprandial period and support the hypothesis that vHC neurons form a memory of a meal and inhibit subsequent intake. © 2016 Wiley Periodicals, Inc.

  4. Reliability of Transcallosal Inhibition in Healthy Adults

    PubMed Central

    Fleming, Melanie K.; Newham, Di J.

    2017-01-01

    Transcallosal inhibition (TCI), assessed using transcranial magnetic stimulation, can provide insight into the neurophysiology of aging and of neurological disorders such as stroke. However, the reliability of TCI using the ipsilateral silent period (iSP) has not been formally assessed, despite its use in longitudinal studies. This study aimed to determine the reliability of iSP onset latency, duration and depth in healthy young and older adults. A sample of 18 younger (mean age 27.7 years, range: 19–42) and 13 older healthy adults (mean age 68.1 years, range: 58–79) attended four sessions whereby the iSP was measured from the first dorsal interosseous (FDI) muscle of each hand. 20 single pulse stimuli were delivered to each primary motor cortex at 80% maximum stimulator output while the participant maintained an isometric contraction of the ipsilateral FDI. The average onset latency, duration of the iSP, and depth of inhibition relative to baseline electromyography activity was calculated for each hand in each session. Intraclass correlation coefficients (ICCs) were calculated for all four sessions, or the first two sessions only. For iSP onset latency the reliability ranged from poor to good. For iSP duration there was moderate to good reliability (ICC > 0.6). Depth of inhibition demonstrated variation in reproducibility depending on which hand was assessed and whether two or four sessions were compared. Bland and Altman analyses showed wide limits of agreement between the first two sessions, particularly for iSP depth. However, there was no systematic pattern to the variability. These results indicate that although iSP duration is reliable in healthy adults, changes in longitudinal studies should be interpreted with caution, particularly for iSP depth. Future studies are needed to determine reliability in clinical populations. PMID:28119588

  5. Interferon-γ Inhibits Ebola Virus Infection.

    PubMed

    Rhein, Bethany A; Powers, Linda S; Rogers, Kai; Anantpadma, Manu; Singh, Brajesh K; Sakurai, Yasuteru; Bair, Thomas; Miller-Hunt, Catherine; Sinn, Patrick; Davey, Robert A; Monick, Martha M; Maury, Wendy

    2015-01-01

    Ebola virus outbreaks, such as the 2014 Makona epidemic in West Africa, are episodic and deadly. Filovirus antivirals are currently not clinically available. Our findings suggest interferon gamma, an FDA-approved drug, may serve as a novel and effective prophylactic or treatment option. Using mouse-adapted Ebola virus, we found that murine interferon gamma administered 24 hours before or after infection robustly protects lethally-challenged mice and reduces morbidity and serum viral titers. Furthermore, we demonstrated that interferon gamma profoundly inhibits Ebola virus infection of macrophages, an early cellular target of infection. As early as six hours following in vitro infection, Ebola virus RNA levels in interferon gamma-treated macrophages were lower than in infected, untreated cells. Addition of the protein synthesis inhibitor, cycloheximide, to interferon gamma-treated macrophages did not further reduce viral RNA levels, suggesting that interferon gamma blocks life cycle events that require protein synthesis such as virus replication. Microarray studies with interferon gamma-treated human macrophages identified more than 160 interferon-stimulated genes. Ectopic expression of a select group of these genes inhibited Ebola virus infection. These studies provide new potential avenues for antiviral targeting as these genes that have not previously appreciated to inhibit negative strand RNA viruses and specifically Ebola virus infection. As treatment of interferon gamma robustly protects mice from lethal Ebola virus infection, we propose that interferon gamma should be further evaluated for its efficacy as a prophylactic and/or therapeutic strategy against filoviruses. Use of this FDA-approved drug could rapidly be deployed during future outbreaks.

  6. Taste Coding after Selective Inhibition by Chlorhexidine

    PubMed Central

    Wang, Miao-Fen; Marks, Lawrence E.

    2009-01-01

    Coding of the complex tastes of ionic stimuli in humans was studied by combining taste confusion matrix (TCM) methodology and treatment with chlorhexidine gluconate. The TCM evaluates discrimination of multiple stimuli simultaneously. Chlorhexidine, a bis-biguanide antiseptic, reversibly inhibits salty taste and tastes of a subset of bitter stimuli, including quinine hydrochloride. Identifications of salty (NaCl, “salt”), bitter (quinine·HCl, “quinine”), sweet (sucrose, “sugar”), and sour (citric acid, “acid”) prototypes, alone and as components of binary mixtures, were measured under 4 conditions. One was a water-rinse control and the others had the salt and quinine tastes progressively reduced by treatment with 1 mM chlorhexidine, 3 mM chlorhexidine, and ultimately to zero by elimination of NaCl and quinine·HCl. Treatment with chlorhexidine perturbed identification of salt more than quinine; both were thereafter more often confused with “water” and unidentified when mixed with sucrose or citric acid. All pairwise discriminations that depended on the tastes of NaCl and quinine·HCl deteriorated, and although H2O was mistakenly identified as quinine after chlorhexidine, this may have been a decisional bias. Other confusions reflected “unprompted mixture analysis” and an obscuring of salt taste by a less-inhibited stronger quinine or sugar or acid tastes in mixtures. Partial inhibition of the tastes of NaCl and quinine·HCl by chlorhexidine was considered in the context of multiple receptors for the 2 compounds. Discrimination among prototypic stimuli with varying strengths was consistent with a gustatory system that evaluates a small number of independent tastes. PMID:19703921

  7. Center-Surround Inhibition in Working Memory.

    PubMed

    Kiyonaga, Anastasia; Egner, Tobias

    2016-01-11

    Directing visual attention toward a particular feature or location in the environment suppresses processing of nearby stimuli [1-4]. Echoing the center-surround organization of retinal ganglion cell receptive fields [5], and biasing of competitive local neuronal dynamics in favor of task-relevant stimuli [6], this "inhibitory surround" attention mechanism accentuates the demarcation between task-relevant and irrelevant items. Here, we show that internally maintaining a color stimulus in working memory (WM), rather than visually attending the stimulus in the external environment, produces an analogous pattern of inhibition for stimuli that are nearby in color space. Replicating a well-known effect of attentional capture by stimuli that match WM content [7], visual attention was biased toward (task-irrelevant) stimuli that exactly matched a WM item. This bias was curtailed, however, for stimuli that were very similar to the WM content (i.e., within the inhibitory zone surrounding the focus of WM) and recovered for less similar stimuli (i.e., beyond the bounds of the inhibitory surround). Moreover, the expression of this inhibition effect was positively associated with WM performance across observers. In a second experiment, inhibition also occurred between two similar items simultaneously held in WM. This suggests that maintenance in WM is characterized by an excitatory peak centered on the focus of (internal) attention, surrounded by an inhibitory zone to limit interference by irrelevant and confusable representations. Here, thus, we show for the first time that the same center-surround selection mechanism that focuses visual attention on sensory stimuli also selectively maintains internally activated representations in WM.

  8. Inhibition by Somatostatin Interneurons in Olfactory Cortex

    PubMed Central

    Large, Adam M.; Kunz, Nicholas A.; Mielo, Samantha L.; Oswald, Anne-Marie M.

    2016-01-01

    Inhibitory circuitry plays an integral role in cortical network activity. The development of transgenic mouse lines targeting unique interneuron classes has significantly advanced our understanding of the functional roles of specific inhibitory circuits in neocortical sensory processing. In contrast, considerably less is known about the circuitry and function of interneuron classes in piriform cortex, a paleocortex responsible for olfactory processing. In this study, we sought to utilize transgenic technology to investigate inhibition mediated by somatostatin (SST) interneurons onto pyramidal cells (PCs), parvalbumin (PV) interneurons, and other interneuron classes. As a first step, we characterized the anatomical distributions and intrinsic properties of SST and PV interneurons in four transgenic lines (SST-cre, GIN, PV-cre, and G42) that are commonly interbred to investigate inhibitory connectivity. Surprisingly, the distributions SST and PV cell subtypes targeted in the GIN and G42 lines were sparse in piriform cortex compared to neocortex. Moreover, two-thirds of interneurons recorded in the SST-cre line had electrophysiological properties similar to fast spiking (FS) interneurons rather than regular (RS) or low threshold spiking (LTS) phenotypes. Nonetheless, like neocortex, we find that SST-cells broadly inhibit a number of unidentified interneuron classes including putatively identified PV cells and surprisingly, other SST cells. We also confirm that SST-cells inhibit pyramidal cell dendrites and thus, influence dendritic integration of afferent and recurrent inputs to the piriform cortex. Altogether, our findings suggest that SST interneurons play an important role in regulating both excitation and the global inhibitory network during olfactory processing. PMID:27582691

  9. Cannabidiol inhibits angiogenesis by multiple mechanisms

    PubMed Central

    Solinas, M; Massi, P; Cantelmo, AR; Cattaneo, MG; Cammarota, R; Bartolini, D; Cinquina, V; Valenti, M; Vicentini, LM; Noonan, DM; Albini, A; Parolaro, D

    2012-01-01

    BACKGROUND AND PURPOSE Several studies have demonstrated anti-proliferative and pro-apoptotic actions of cannabinoids on various tumours, together with their anti-angiogenic properties. The non-psychoactive cannabinoid cannabidiol (CBD) effectively inhibits the growth of different types of tumours in vitro and in vivo and down-regulates some pro-angiogenic signals produced by glioma cells. As its anti-angiogenic properties have not been thoroughly investigated to date, and given its very favourable pharmacological and toxicological profile, here, we evaluated the ability of CBD to modulate tumour angiogenesis. EXPERIMENTAL APPROACH Firstly, we evaluated the effect of CBD on human umbilical vein endothelial cell (HUVEC) proliferation and viability – through [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and FACS analysis – and in vitro motility – both in a classical Boyden chamber test and in a wound-healing assay. We next investigated CBD effects on different angiogenesis-related proteins released by HUVECs, using an angiogenesis array kit and an ELISA directed at MMP2. Then we evaluated its effects on in vitro angiogenesis in treated HUVECs invading a Matrigel layer and in HUVEC spheroids embedded into collagen gels, and further characterized its effects in vivo using a Matrigel sponge model of angiogenesis in C57/BL6 mice. KEY RESULTS CBD induced HUVEC cytostasis without inducing apoptosis, inhibited HUVEC migration, invasion and sprouting in vitro, and angiogenesis in vivo in Matrigel sponges. These effects were associated with the down-modulation of several angiogenesis-related molecules. CONCLUSIONS AND IMPLICATIONS This study reveals that CBD inhibits angiogenesis by multiple mechanisms. Its dual effect on both tumour and endothelial cells supports the hypothesis that CBD has potential as an effective agent in cancer therapy. PMID:22624859

  10. Inhibiting bacterial toxins by channel blockage.

    PubMed

    Bezrukov, Sergey M; Nestorovich, Ekaterina M

    2016-03-01

    Emergent rational drug design techniques explore individual properties of target biomolecules, small and macromolecule drug candidates, and the physical forces governing their interactions. In this minireview, we focus on the single-molecule biophysical studies of channel-forming bacterial toxins that suggest new approaches for their inhibition. We discuss several examples of blockage of bacterial pore-forming and AB-type toxins by the tailor-made compounds. In the concluding remarks, the most effective rationally designed pore-blocking antitoxins are compared with the small-molecule inhibitors of ion-selective channels of neurophysiology.

  11. Tooth brushing inhibits oral bacteria in dogs.

    PubMed

    Watanabe, Kazuhiro; Hayashi, Kotaro; Kijima, Saku; Nonaka, Chie; Yamazoe, Kazuaki

    2015-10-01

    In this study, scaling, polishing and daily tooth brushing were performed in 20 beagle dogs, and the number of oral bacteria was determined using a bacterial counter. The dogs were randomized into the scaling (S), scaling + polishing (SP), scaling + tooth daily brushing (SB) and scaling + polishing + tooth daily brushing (SPB) groups. Samples were collected from the buccal surface of the maxillary fourth premolars of the dogs immediately after scaling and every week thereafter from weeks 1 to 8. Throughout the study, the number of bacteria was significantly lower in the SB and SPB groups compared with the S group. The findings suggest that daily tooth brushing inhibited oral bacterial growth in the dogs.

  12. Emergence of clustering: Role of inhibition

    NASA Astrophysics Data System (ADS)

    Dwivedi, Sanjiv K.; Jalan, Sarika

    2014-09-01

    Though biological and artificial complex systems having inhibitory connections exhibit a high degree of clustering in their interaction pattern, the evolutionary origin of clustering in such systems remains a challenging problem. Using genetic algorithm we demonstrate that inhibition is required in the evolution of clique structure from primary random architecture, in which the fitness function is assigned based on the largest eigenvalue. Further, the distribution of triads over nodes of the network evolved from mixed connections reveals a negative correlation with its degree providing insight into origin of this trend observed in real networks.

  13. Inhibiting bacterial toxins by channel blockage

    PubMed Central

    Bezrukov, Sergey M.; Nestorovich, Ekaterina M.

    2015-01-01

    Emergent rational drug design techniques explore individual properties of target biomolecules, small and macromolecule drug candidates, and the physical forces governing their interactions. In this minireview, we focus on the single-molecule biophysical studies of channel-forming bacterial toxins that suggest new approaches for their inhibition. We discuss several examples of blockage of bacterial pore-forming and AB-type toxins by the tailor-made compounds. In the concluding remarks, the most effective rationally designed pore-blocking antitoxins are compared with the small-molecule inhibitors of ion-selective channels of neurophysiology. PMID:26656888

  14. Saw palmetto ethanol extract inhibits adipocyte differentiation.

    PubMed

    Villaverde, Nicole; Galvis, Adriana; Marcano, Adriana; Priestap, Horacio A; Bennett, Bradley C; Barbieri, M Alejandro

    2013-07-01

    The fruits of saw palmetto have been used for the treatment of a variety of urinary and reproductive system problems. In this study we investigated whether the fruit extracts affect in vitro adipogenesis. Saw palmetto ethanol extract inhibited the lipid droplet accumulation by induction media in a dose-dependent manner, and it also attenuated the protein expressions of C-EBPα and PPARγ. Phosphorylation of Erk1/2 and Akt1 were also decreased by saw palmetto ethanol extract. This report suggests that saw palmetto extracts selectively affect the adipocyte differentiation through the modulation of several key factors that play a critical role during adipogenesis.

  15. Formation and inhibition of photochemical smog

    SciTech Connect

    Heicklen, J.

    1987-01-01

    Photochemical smog is caused by a free-radical chain mechanism which converts NO to NO/sub 2/. The NO/sub 2/ further reacts to produce ozone, nitric acid, and peracylnitrates. This chain mechanism can be inhibited by suitable free-radical scavengers. The chemistry and toxicology of one such free-radical scavenger, diethylhydroxylamine, has been studied in depth. It has been shown to be effective, safe, and practical for use in urban atmospheres to prevent photochemical smog formation. 42 references.

  16. Aminopeptidase from Brevibacterium linens: activation and inhibition.

    PubMed

    Foissy, H

    1978-04-18

    Activation and inhibition of a purified aminopeptidase from Brevibacterium linens was investigated using L-alpha-leucyl-4-nitroanilide and L-leucyl-L-leucine as substrates. The enzyme was activated by cobalt, provided that the enzyme was preincubated with the metal. Strong inhibitory effects were derived from heavy metals, metal-complexing compounds, reducing agents, the modification of aromatic amino acids, and the presence of hydrophobic substances or certain amino acids in the test mixtures. Supposing that this B. linens aminopeptidase plays a part during surface-ripening of cheeses, possible consequences of specific technological conditions for its activity are discussed.

  17. Multiple components of ipsilaterally evoked inhibition in the inferior colliculus.

    PubMed

    Klug, A; Bauer, E E; Pollak, G D

    1999-08-01

    The central nucleus of the inferior colliculus (ICc) receives a large number of convergent inputs that are both excitatory and inhibitory. Although excitatory inputs typically are evoked by stimulation of the contralateral ear, inhibitory inputs can be recruited by either ear. Here we evaluate ipsilaterally evoked inhibition in single ICc cells in awake Mexican free-tailed bats. The principal question we addressed concerns the degree to which ipsilateral inhibition at the ICc suppresses contralaterally evoked discharges and thus creates the excitatory-inhibitory (EI) properties of ICc neurons. To study ipsilaterally evoked inhibition, we iontophoretically applied excitatory neurotransmitters and visualized the ipsilateral inhibition as a gap in the carpet of background activity evoked by the transmitters. Ipsilateral inhibition was seen in 86% of ICc cells. The inhibition in most cells had both glycinergic and GABAergic components that could be blocked by the iontophoretic application of bicuculline and strychnine. In 80% of the cells that were inhibited, the ipsilateral inhibition and contralateral excitation were temporally coincident. In many of these cells, the ipsilateral inhibition suppressed contralateral discharges and thus generated the cell's EI property in the ICc. In other cells, the ipsilateral inhibition was coincident with the initial portion of the excitation, but the inhibition was only 2-4 ms in duration and suppressed only the first few contralaterally evoked discharges. The suppression was so slight that it often could not be detected as a decrease in the spike count generated by increasing ipsilateral intensities. Twenty percent of the cells that expressed inhibition, however, had inhibitory latencies that were longer than the excitatory latencies. In these neurons, the inhibition arrived too late to suppress most or any of the discharges. Finally, in the majority of cells, the ipsilateral inhibition persisted for tens of milliseconds beyond

  18. Optogenetic and chemogenetic strategies for sustained inhibition of pain

    PubMed Central

    Iyer, Shrivats M.; Vesuna, Sam; Ramakrishnan, Charu; Huynh, Karen; Young, Stephanie; Berndt, Andre; Lee, Soo Yeun; Gorini, Christopher J.; Deisseroth, Karl; Delp, Scott L.

    2016-01-01

    Spatially targeted, genetically-specific strategies for sustained inhibition of nociceptors may help transform pain science and clinical management. Previous optogenetic strategies to inhibit pain have required constant illumination, and chemogenetic approaches in the periphery have not been shown to inhibit pain. Here, we show that the step-function inhibitory channelrhodopsin, SwiChR, can be used to persistently inhibit pain for long periods of time through infrequent transdermally delivered light pulses, reducing required light exposure by >98% and resolving a long-standing limitation in optogenetic inhibition. We demonstrate that the viral expression of the hM4D receptor in small-diameter primary afferent nociceptor enables chemogenetic inhibition of mechanical and thermal nociception thresholds. Finally, we develop optoPAIN, an optogenetic platform to non-invasively assess changes in pain sensitivity, and use this technique to examine pharmacological and chemogenetic inhibition of pain. PMID:27484850

  19. A Comparator View of Pavlovian and Differential Inhibition

    PubMed Central

    Urcelay, Gonzalo P.; Miller, Ralph R.

    2007-01-01

    In 3 experiments using rats as subjects, the authors varied trial spacing to investigate the conditions under which Pavlovian and differential inhibition are observed. Experiment 1 compared Pavlovian and differential inhibition with spaced training trials. Spaced trials resulted in only the Pavlovian inhibitor passing both summation and retardation tests. Conversely, Experiment 2 compared these 2 types of inhibition with massed training trials. This training resulted in only the differential inhibitor passing both tests for conditioned inhibition. Finally, in Experiment 3 all subjects experienced Pavlovian inhibition training with massed trials. Although this training by itself did not result in behavior indicative of inhibition, subjects that also experienced posttraining extinction of the training context did pass both tests for inhibition. Overall, these results are anticipated by the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) but are problematic for most contemporary associative learning theories. PMID:16834494

  20. A comparator view of Pavlovian and differential inhibition.

    PubMed

    Urcelay, Gonzalo P; Miller, Ralph R

    2006-07-01

    In 3 experiments using rats as subjects, the authors varied trial spacing to investigate the conditions under which Pavlovian and differential inhibition are observed. Experiment 1 compared Pavlovian and differential inhibition with spaced training trials. Spaced trials resulted in only the Pavlovian inhibitor passing both summation and retardation tests. Conversely, Experiment 2 compared these 2 types of inhibition with massed training trials. This training resulted in only the differential inhibitor passing both tests for conditioned inhibition. Finally, in Experiment 3 all subjects experienced Pavlovian inhibition training with massed trials. Although this training by itself did not result in behavior indicative of inhibition, subjects that also experienced posttraining extinction of the training context did pass both tests for inhibition. Overall, these results are anticipated by the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) but are problematic for most contemporary associative learning theories.

  1. Metal ion substrate inhibition of ferrochelatase.

    PubMed

    Hunter, Gregory A; Sampson, Matthew P; Ferreira, Gloria C

    2008-08-29

    Ferrochelatase catalyzes the insertion of ferrous iron into protoporphyrin IX to form heme. Robust kinetic analyses of the reaction mechanism are complicated by the instability of ferrous iron in aqueous solution, particularly at alkaline pH values. At pH 7.00 the half-life for spontaneous oxidation of ferrous ion is approximately 2 min in the absence of metal complexing additives, which is sufficient for direct comparisons of alternative metal ion substrates with iron. These analyses reveal that purified recombinant ferrochelatase from both murine and yeast sources inserts not only ferrous iron but also divalent cobalt, zinc, nickel, and copper into protoporphyrin IX to form the corresponding metalloporphyrins but with considerable mechanistic variability. Ferrous iron is the preferred metal ion substrate in terms of apparent k(cat) and is also the only metal ion substrate not subject to severe substrate inhibition. Substrate inhibition occurs in the order Cu(2+) > Zn(2+) > Co(2+) > Ni(2+) and can be alleviated by the addition of metal complexing agents such as beta-mercaptoethanol or imidazole to the reaction buffer. These data indicate the presence of two catalytically significant metal ion binding sites that may coordinately regulate a selective processivity for the various potential metal ion substrates.

  2. Effects of renin inhibition in systemic hypertension.

    PubMed

    Anderson, P W; Do, Y S; Schambelan, M; Horton, R; Boger, R S; Luther, R R; Hsueh, W A

    1990-12-01

    The effect of the direct renin inhibitor enalkiren (Abbott Laboratories) was examined in 8 healthy patients with essential hypertension. With an unrestricted sodium diet, plasma renin concentration was inhibited within 10 minutes by intravenous enalkiren and remained essentially undetectable for greater than or equal to 6 hours (11.9 +/- 4 to 1.0 +/- 0.6 ng angiotensin I/ml/hour, p less than 0.05). Mean arterial blood pressure declined gradually (108 +/- 5 to 84 +/- 4 mm Hg, p = 0.02), as did plasma aldosterone concentration (14.4 +/- 3.8 to 4.4 +/- 0.8 ng/dl, p = 0.03), whereas plasma immunoreactive active renin concentration increased progressively (35 +/- 14 to 160 +/- 60 pg/ml, p greater than 0.05). Urinary excretion of the stable metabolite of prostacyclin (6-keto-prostaglandin F1 alpha) decreased slightly, but not significantly (42 +/- 10 to 33 +/- 11 ng/g creatinine, p = 0.13). The addition of a diuretic decreased baseline blood pressure and increased baseline plasma renin and aldosterone values. Blood pressure responses to enalkiren were slightly (though not significantly) greater than those observed before diuretic administration. We conclude that enalkiren is effective in decreasing blood pressure and in inhibiting the renin system, without significantly altering urinary prostacyclin excretion, in patients with essential hypertension. These results suggest that the renin system contributes to the maintenance of elevated blood pressure in some patients with essential hypertension.

  3. Understanding biocatalyst inhibition by carboxylic acids.

    PubMed

    Jarboe, Laura R; Royce, Liam A; Liu, Ping

    2013-09-03

    Carboxylic acids are an attractive biorenewable chemical in terms of their flexibility and usage as precursors for a variety of industrial chemicals. It has been demonstrated that such carboxylic acids can be fermentatively produced using engineered microbes, such as Escherichia coli and Saccharomyces cerevisiae. However, like many other attractive biorenewable fuels and chemicals, carboxylic acids become inhibitory to these microbes at concentrations below the desired yield and titer. In fact, their potency as microbial inhibitors is highlighted by the fact that many of these carboxylic acids are routinely used as food preservatives. This review highlights the current knowledge regarding the impact that saturated, straight-chain carboxylic acids, such as hexanoic, octanoic, decanoic, and lauric acids can have on E. coli and S. cerevisiae, with the goal of identifying metabolic engineering strategies to increase robustness. Key effects of these carboxylic acids include damage to the cell membrane and a decrease of the microbial internal pH. Certain changes in cell membrane properties, such as composition, fluidity, integrity, and hydrophobicity, and intracellular pH are often associated with increased tolerance. The availability of appropriate exporters, such as Pdr12, can also increase tolerance. The effect on metabolic processes, such as maintaining appropriate respiratory function, regulation of Lrp activity and inhibition of production of key metabolites such as methionine, are also considered. Understanding the mechanisms of biocatalyst inhibition by these desirable products can aid in the engineering of robust strains with improved industrial performance.

  4. Inhibition of saccades elicits attentional suppression.

    PubMed

    Dhawan, Saurabh; Deubel, Heiner; Jonikaitis, Donatas

    2013-05-17

    Visuospatial attention has been shown to have a central role in planning and generation of saccades but what role, if any, it plays in inhibition of saccades remains unclear. In this study, we used an oculomotor delayed match- or nonmatch-to-sample task in which a cued location has to be encoded and memorized for one of two very different goals-to plan a saccade to it or to avoid making a saccade to it. We measured the spatial allocation of attention during the delay and found that while marking a location as a future saccade target resulted in an attentional benefit at that location, marking it as forbidden to saccades led to an attentional cost. Additionally, saccade trajectories were found to deviate away more from the "don't look" location than from a saccade-irrelevant distractor confirming greater inhibition of an actively forbidden location in oculomotor programming. Our finding that attention is suppressed at locations forbidden to saccades confirms and complements the claim of a selective and obligatory coupling between saccades and attention-saccades at the memorized location could neither be planned nor suppressed independent of a corresponding effect on attentional performance.

  5. Response inhibition and attentional control in anxiety.

    PubMed

    Pacheco-Unguetti, Antonia Pilar; Acosta, Alberto; Lupiáñez, Juan; Román, Naiker; Derakshan, Nazanin

    2012-01-01

    Traditionally, anxiety has been associated with a selective attentional bias for threat and a decreased capacity in attentional control. In two different experiments, we investigated whether individuals with different levels of self-reported state anxiety (Experiment 1) and induced anxiety (Experiment 2) had impaired response inhibition processes (attentional control deficit) as characterized by a different response style in the presence of negative stimuli under low and high perceptual load conditions. A go/no-go paradigm with emotional distractors (angry, happy, and neutral faces) was used to provide measures of perceptual sensitivity, inhibition, and response style. Our findings showed that perceptual sensitivity, as assessed by the d' parameter of signal detection theory, was reduced in all participants for angry faces under low perceptual load, where enough perceptual resources were available to be attracted by distractors. Importantly, despite similar perceptual sensitivity, the beta parameter indicated that high state anxiety individuals in both experiments were less flexible at adjusting to task demands in the presence of angry face distractors by adopting a stricter criterion. Implications of findings are discussed within current models of attentional control in anxiety.

  6. Salinomycin, a polyether ionophoric antibiotic, inhibits adipogenesis.

    PubMed

    Szkudlarek-Mikho, Maria; Saunders, Rudel A; Yap, Sook Fan; Ngeow, Yun Fong; Chin, Khew-Voon

    2012-11-30

    The polyether ionophoric antibiotics including monensin, salinomycin, and narasin, are widely used in veterinary medicine and as food additives and growth promoters in animal husbandry including poultry farming. Their effects on human health, however, are not fully understood. Recent studies showed that salinomycin is a cancer stem cell inhibitor. Since poultry consumption has risen sharply in the last three decades, we asked whether the consumption of meat tainted with growth promoting antibiotics might have effects on adipose cells. We showed in this report that the ionophoric antibiotics inhibit the differentiation of preadipocytes into adipocytes. The block of differentiation is not due to the induction of apoptosis nor the inhibition of cell proliferation. In addition, salinomycin also suppresses the transcriptional activity of the CCAAT/enhancer binding proteins and the peroxisome proliferator-activated receptor γ. These results suggest that the ionophoric antibiotics can be exploited as novel anti-obesity therapeutics and as pharmacological probes for the study of adipose biology. Further, the pharmacological effects of salinomycin could be a harbinger of its toxicity on the adipose tissue and other susceptible target cells in cancer therapy.

  7. Calcineurin/NFAT signalling inhibits myeloid haematopoiesis

    PubMed Central

    Fric, Jan; Lim, Clarice X F; Koh, Esther G L; Hofmann, Benjamin; Chen, Jinmiao; Tay, Hock Soon; Isa, Siti Aminah Bte Mohammad; Mortellaro, Alessandra; Ruedl, Christiane; Ricciardi-Castagnoli, Paola

    2012-01-01

    Nuclear factor of activated T cells (NFAT) comprises a family of transcription factors that regulate T cell development, activation and differentiation. NFAT signalling can also mediate granulocyte and dendritic cell (DC) activation, but it is unknown whether NFAT influences their development from progenitors. Here, we report a novel role for calcineurin/NFAT signalling as a negative regulator of myeloid haematopoiesis. Reconstituting lethally irradiated mice with haematopoietic stem cells expressing an NFAT-inhibitory peptide resulted in enhanced development of the myeloid compartment. Culturing bone marrow cells in media supplemented with Flt3-L in the presence of the calcineurin/NFAT inhibitor Cyclosporin A increased numbers of differentiated DC. Global gene expression analysis of untreated DC and NFAT-inhibited DC revealed differential expression of transcripts that regulate cell cycle and apoptosis. In conclusion, these results provide evidence that calcineurin/NFAT signalling negatively regulates myeloid lineage development. The finding that inhibition of NFAT enhances myeloid development provides a novel insight into understanding how the treatment with drugs targeting calcineurin/NFAT signalling influence the homeostasis of the innate immune system. PMID:22311511

  8. In search of lost presynaptic inhibition.

    PubMed

    Rudomin, Pablo

    2009-06-01

    This chapter presents an historical review on the development of some of the main findings on presynaptic inhibition. Particular attention is given to recent studies pertaining the differential GABAa control of the synaptic effectiveness of muscle, cutaneous and articular afferents, to some of the problems arising with the identification of the interneurons mediating the GABAergic depolarization of primary afferents (PAD) of muscle afferents, on the influence of the spontaneous activity of discrete sets of dorsal horn neurons on the pathways mediating PAD of muscle and cutaneous afferents, and to the unmasking of the cutaneous-evoked responses in the lumbosacral spinal cord and associated changes in tonic PAD that follow acute and chronic section of cutaneous nerves. The concluding remarks are addressed to several issues that need to be considered to have a better understanding of the functional role of presynaptic inhibition and PAD on motor performance and sensory processing and on their possible contribution to the shaping of a higher coherence between the cortically programmed and the executed movements.

  9. Tonic inhibition of chemotaxis in human plasma

    PubMed Central

    Malawista, Stephen E.; de Boisfleury Chevance, Anne; van Damme, Jo; Serhan, Charles N.

    2008-01-01

    We found exaggerated chemotaxis in plasma treated with EDTA and thought that the EDTA might itself be inhibiting a tonic inhibitor(s) of chemotaxis. Our plasma fractionations suggested that evidence should be sought for a lipid moiety carrying this activity, and on spectrometry (LC-MS-MS together with GC-MS analyses), the biologically active but not the inactive fraction contained oleic and arachidonic acids. Because fatty acids are largely protein bound, we flooded plasma preparations with delipidated albumin, reasoning that it would bind enough fatty acids, including inhibitory ones, to counter their tonic inhibition. Indeed, we observed dramatic increases in chemotaxis. Hence, adding delipidated albumin to plasma has a similar effect to that of adding EDTA—amplification of the chemotactic response. Oleic acid in physiologic concentrations diminishes the magnifying effects of both EDTA and of delipidated albumin, and in fact diminishes the chemotactic response even without the presence of the amplifiers of chemotaxis. In contrast, arachidonic acid amplifies further the effect of EDTA but not of delipidated albumin, and this augmentation appears to be caused by an EDTA-dependent enrichment of the chemotactic gradient with leukotriene B4 (LTB4). We conclude that oleic acid, the blood levels of which vary among individuals, is at least one tonic inhibitor of chemotaxis in plasma. PMID:18997012

  10. Inhibition Of Washed Sludge With Sodium Nitrite

    SciTech Connect

    Congdon, J. W.; Lozier, J. S.

    2012-09-25

    This report describes the results of electrochemical tests used to determine the relationship between the concentration of the aggressive anions in washed sludge and the minimum effective inhibitor concentration. Sodium nitrate was added as the inhibitor because of its compatibility with the DWPF process. A minimum of 0.05M nitrite is required to inhibit the washed sludge simulant solution used in this study. When the worst case compositions and safety margins are considered, it is expected that a minimum operating limit of nearly 0.1M nitrite will be specified. The validity of this limit is dependent on the accuracy of the concentrations and solubility splits previously reported. Sodium nitrite additions to obtain 0.1M nitrite concentrations in washed sludge will necessitate the additional washing of washed precipitate in order to decrease its sodium nitrite inhibitor requirements sufficiently to remain below the sodium limits in the feed to the DWPF. Nitrite will be the controlling anion in "fresh" washed sludge unless the soluble chloride concentration is about ten times higher than predicted by the solubility splits. Inhibition of "aged" washed sludge will not be a problem unless significant chloride dissolution occurs during storage. It will be very important tomonitor the composition of washed sludge during processing and storage.

  11. Oxidation inhibits iron-induced blood coagulation.

    PubMed

    Pretorius, Etheresia; Bester, Janette; Vermeulen, Natasha; Lipinski, Boguslaw

    2013-01-01

    Blood coagulation under physiological conditions is activated by thrombin, which converts soluble plasma fibrinogen (FBG) into an insoluble clot. The structure of the enzymatically-generated clot is very characteristic being composed of thick fibrin fibers susceptible to the fibrinolytic degradation. However, in chronic degenerative diseases, such as atherosclerosis, diabetes mellitus, cancer, and neurological disorders, fibrin clots are very different forming dense matted deposits (DMD) that are not effectively removed and thus create a condition known as thrombosis. We have recently shown that trivalent iron (ferric ions) generates hydroxyl radicals, which subsequently convert FBG into abnormal fibrin clots in the form of DMDs. A characteristic feature of DMDs is their remarkable and permanent resistance to the enzymatic degradation. Therefore, in order to prevent thrombotic incidences in the degenerative diseases it is essential to inhibit the iron-induced generation of hydroxyl radicals. This can be achieved by the pretreatment with a direct free radical scavenger (e.g. salicylate), and as shown in this paper by the treatment with oxidizing agents such as hydrogen peroxide, methylene blue, and sodium selenite. Although the actual mechanism of this phenomenon is not yet known, it is possible that hydroxyl radicals are neutralized by their conversion to the molecular oxygen and water, thus inhibiting the formation of dense matted fibrin deposits in human blood.

  12. Neuroprotective Mechanisms Mediated by CDK5 Inhibition

    PubMed Central

    Mushtaq, Gohar; Greig, Nigel H.; Anwar, Firoz; Al-Abbasi, Fahad A.; Zamzami, Mazin A.; Al-Talhi, Hasan A.; Kamal, Mohammad A.

    2016-01-01

    Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase belonging to the family of cyclin-dependent kinases. In addition to maintaining the neuronal architecture, CDK5 plays an important role in the regulation of synaptic plasticity, neurotransmitter release, neuron migration and neurite outgrowth. Although various reports have shown links between neurodegeneration and deregulation of cyclin-dependent kinases, the specific role of CDK5 inhibition in causing neuroprotection in cases of neuronal insult or in neurodegenerative diseases is not well-understood. This article discusses current evidence for the involvement of CDK5 deregulation in neurodegenerative disorders and neurodegeneration associated with stroke through various mechanisms. These include upregulation of cyclin D1 and overactivation of CDK5 mediated neuronal cell death pathways, aberrant hyperphosphorylation of human tau proteins and/or neurofilament proteins, formation of neurofibrillary lesions, excitotoxicity, cytoskeletal disruption, motor neuron death (due to abnormally high levels of CDK5/p25) and colchicine-induced apoptosis in cerebellar granule neurons. A better understanding of the role of CDK5 inhibition in neuroprotective mechanisms will help scientists and researchers to develop selective, safe and efficacious pharmacological inhibitors of CDK5 for therapeutic use against human neurodegenerative disorders, such as Alzheimer’s disease, amyotrophic lateral sclerosis and neuronal loss associated with stroke. PMID:26601962

  13. Inhibition of Aflatoxin Production by Surfactants

    PubMed Central

    Rodriguez, Susan B.; Mahoney, Noreen E.

    1994-01-01

    The effect of 12 surfactants on aflatoxin production, growth, and conidial germination by the fungus Aspergillus flavus is reported. Five nonionic surfactants, Triton X-100, Tergitol NP-7, Tergitol NP-10, polyoxyethylene (POE) 10 lauryl ether, and Latron AG-98, reduced aflatoxin production by 96 to 99% at 1% (wt/vol). Colony growth was restricted by the five nonionic surfactants at this concentration. Aflatoxin production was inhibited 31 to 53% by lower concentrations of Triton X-100 (0.001 to 0.0001%) at which colony growth was not affected. Triton X-301, a POE-derived anionic surfactant, had an effect on colony growth and aflatoxin production similar to that of the five POE-derived nonionic surfactants. Sodium dodecyl sulfate (SDS), an anionic surfactant, and dodecyltrimethylammonium bromide, a cationic surfactant, suppressed conidial germination at 1% (wt/vol). SDS had no effect on aflatoxin production or colony growth at 0.001%. The degree of aflatoxin inhibition by a surfactant appears to be a function of the length of the hydrophobic and hydrophilic chains of POE-derived surfactants. Images PMID:16349144

  14. Prostaglandin synthesis inhibition and postprandial intestinal hyperemia.

    PubMed

    Gallavan, R H; Chou, C C

    1982-02-01

    The effect of prostaglandin synthesis inhibition on the postprandial intestinal hyperemia was examined in the jejunum of anesthetized dogs. Both intravenous and intra-arterial infusion of the cyclooxygenase inhibitors indomethacin and mefenamic acid reduced resting jejunal blood flow and markedly enhanced the food-induced jejunal hyperemia. The jejunal vascular response to food did not change after either intravenous or intra-arterial infusion of the carrier solutions or intra-arterial infusion of angiotensin II. The enhancement of the jejunal hyperemia was associated with an increase in the food-induced increase in jejunal oxygen consumption. Infusion of the cyclooxygenase inhibitors increased the mean amplitude of the monophasic intestinal contractions; however, this did not appear to play a role in the enhancement of the food-induced hyperemia. The study indicates that inhibition of prostaglandin synthesis has a marked effect on the postprandial intestinal hyperemia and that this may be due to its enhancement of the jejunal metabolic response to food. The prostaglandins involved and their mechanism of action are unknown.

  15. Kaempferol inhibits thrombosis and platelet activation.

    PubMed

    Choi, Jun-Hui; Park, Se-Eun; Kim, Sung-Jun; Kim, Seung

    2015-08-01

    The objectives of the present study were to investigate whether kaempferol affects pro-coagulant proteinase activity, fibrin clot formation, blood clot and thrombin (or collagen/epinephrine)-stimulated platelet activation, thrombosis, and coagulation in ICR (Imprinting Control Region) mice and SD (Sprague-Dawley) rats. Kaempferol significantly inhibited the enzymatic activities of thrombin and FXa by 68 ± 1.6% and 52 ± 2.4%, respectively. Kaempferol also inhibited fibrin polymer formation in turbidity. Microscopic analysis was performed using a fluorescent conjugate. Kaempferol completely attenuated phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) 1/2, and phosphoinositide 3-kinase (PI3K)/PKB (AKT) in thrombin-stimulated platelets and delayed aggregation time (clotting) by 34.6% in an assay of collagen/epinephrine-stimulated platelet activation. Moreover, kaempferol protected against thrombosis development in 3 animal models, including collagen/epinephrine- and thrombin-induced acute thromboembolism models and an FeCl3-induced carotid arterial thrombus model. The ex vivo anticoagulant effect of kaempferol was further confirmed in ICR mice. This study demonstrated that kaempferol may be clinically useful due to its ability to reduce or prevent thrombotic challenge.

  16. Dimethyl sulfoxide inhibits NLRP3 inflammasome activation.

    PubMed

    Ahn, Huijeong; Kim, Jeeyoung; Jeung, Eui-Bae; Lee, Geun-Shik

    2014-04-01

    Dimethyl sulfoxide (DMSO) is an amphipathic molecule that is commonly/widely used as a solvent for biological compounds. In addition, DMSO has been studied as a medication for the treatment of inflammation, cystitis, and arthritis. Based on the anti-inflammatory characteristics of DMSO, we elucidated the effects of DMSO on activation of inflammasomes, which are cytoplasmic multi-protein complexes that mediate the maturation of interleukin (IL)-1β by activating caspase-1 (Casp1). In the present study, we prove that DMSO attenuated IL-1β maturation, Casp1 activity, and ASC pyroptosome formation via NLRP3 inflammasome activators. Further, NLRC4 and AIM2 inflammasome activity were not affected, suggesting that DMSO is a selective inhibitor of the NLRP3 inflammasomes. The anti-inflammatory effect of DMSO was further confirmed in animal, LPS-endotoxin sepsis and inflammatory bowel disease models. In addition, DMSO inhibited LPS-mediating IL-1s transcription. Taken together, DMSO shows anti-inflammatory characteristics, attenuates NLRP3 inflammasome activation, and mediates inhibition of IL-1s transcription.

  17. Phenols displaying tyrosinase inhibition from Humulus lupulus.

    PubMed

    Kim, Dae Wook; Woo, Hyun Sim; Kim, Jeong Yoon; Ryuk, Jin Ah; Park, Ki Hun; Ko, Byoung Seob

    2016-10-01

    Tyrosinase is the rate-limiting enzyme for the production of melanin and other pigments via the oxidation of l-tyrosine. The methanol extract from Humulus lupulus showed potent inhibition against mushroom tyrosinase. The bioactivity-guided fractionation of this methanol extract resulted in the isolation of seven flavonoids (1-7), identified as xanthohumol (1), 4'-O-methylxanthohumol (2), xanthohumol C (3), flavokawain C (4), xanthoumol B (5), 6-prenylnaringenin (6) and isoxanthohumol (7). All isolated flavonoids (1-7) effectively inhibited the monophenolase (IC50s = 15.4-58.4 µM) and diphenolase (IC50s = 27.1-117.4 µM) activities of tyrosinase. Kinetic studies using Lineweaver-Burk and Dixon-plots revealed that chalcones (1-5) were competitive inhibitors, whereas flavanones (6 and 7) exhibited both mixed and non-competitive inhibitory characteristics. In conclusion, this study is the first to demonstrate that the phenolic phytochemicals of H. lupulus display potent inhibitory activities against tyrosinase.

  18. 3-Bromopyruvate inhibits human gastric cancer tumor growth in nude mice via the inhibition of glycolysis.

    PubMed

    Xian, Shu-Lin; Cao, Wei; Zhang, Xiao-Dong; Lu, Yun-Fei

    2015-02-01

    Tumor cells primarily depend upon glycolysis in order to gain energy. Therefore, the inhibition of glycolysis may inhibit tumor growth. Our previous study demonstrated that 3-bromopyruvate (3-BrPA) inhibited gastric cancer cell proliferation in vitro. However, the ability of 3-BrPA to suppress tumor growth in vivo, and its underlying mechanism, have yet to be elucidated. The aim of the present study was to investigate the inhibitory effect of 3-BrPA in an animal model of gastric cancer. It was identified that 3-BrPA exhibited strong inhibitory effects upon xenograft tumor growth in nude mice. In addition, the antitumor function of 3-BrPA exhibited a dose-effect association, which was similar to that of the chemotherapeutic agent, 5-fluorouracil. Furthermore, 3-BrPA exhibited low toxicity in the blood, liver and kidneys of the nude mice. The present study hypothesized that the inhibitory effect of 3-BrPA is achieved through the inhibition of hexokinase activity, which leads to the downregulation of B-cell lymphoma 2 (Bcl-2) expression, the upregulation of Bcl-2-associated X protein expression and the subsequent activation of caspase-3. These data suggest that 3-BrPA may be a novel therapy for the treatment of gastric cancer.

  19. Distinct Neural Correlates for Two Types of Inhibition in Bilinguals: Response Inhibition versus Interference Suppression

    ERIC Educational Resources Information Center

    Luk, Gigi; Anderson, John A. E.; Craik, Fergus I. M.; Grady, Cheryl; Bialystok, Ellen

    2010-01-01

    To examine the effects of bilingualism on cognitive control, we studied monolingual and bilingual young adults performing a flanker task with functional MRI. The trial types of primary interest for this report were incongruent and no-go trials, representing interference suppression and response inhibition, respectively. Response times were similar…

  20. Glyphosate and AMPA inhibit cancer cell growth through inhibiting intracellular glycine synthesis.

    PubMed

    Li, Qingli; Lambrechts, Mark J; Zhang, Qiuyang; Liu, Sen; Ge, Dongxia; Yin, Rutie; Xi, Mingrong; You, Zongbing

    2013-01-01

    Glycine is a nonessential amino acid that is reversibly converted from serine intracellularly by serine hydroxymethyltransferase. Glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), are analogs to glycine, thus they may inhibit serine hydroxymethyltransferase to decrease intracellular glycine synthesis. In this study, we found that glyphosate and AMPA inhibited cell growth in eight human cancer cell lines but not in two immortalized human normal prostatic epithelial cell lines. AMPA arrested C4-2B and PC-3 cancer cells in the G1/G0 phase and inhibited entry into the S phase of the cell cycle. AMPA also promoted apoptosis in C4-2B and PC-3 cancer cell lines. AMPA upregulated p53 and p21 protein levels as well as procaspase 9 protein levels in C4-2B cells, whereas it downregulated cyclin D3 protein levels. AMPA also activated caspase 3 and induced cleavage of poly (adenosine diphosphate [ADP]-ribose) polymerase. This study provides the first evidence that glyphosate and AMPA can inhibit proliferation and promote apoptosis of cancer cells but not normal cells, suggesting that they have potentials to be developed into a new anticancer therapy.

  1. Triple ACE-ECE-NEP inhibition in heart failure: a comparison with ACE and dual ECE-NEP inhibition.

    PubMed

    Mellin, Virginie; Jeng, Arco Y; Monteil, Christelle; Renet, Sylvanie; Henry, Jean Paul; Thuillez, Christian; Mulder, Paul

    2005-09-01

    Mortality remains high in chronic heart failure (CHF) because under ACE inhibitor treatment other neurohumoral systems remain/become (de)activated, such as the endothelin and atrial natriuretic peptide pathways. Dual endothelin-converting enzyme-neutral endopeptidase (ECE-NEP) inhibition exerts beneficial effects in experimental CHF, but whether "triple" ACE-ECE-NEP inhibition is superior to ACE or ECE-NEP inhibition is unknown. We compared, in rats with CHF, ACE-ECE-NEP to ACE or ECE-NEP inhibition in terms of left ventricular (LV) hemodynamics and remodeling. Benazepril (2 mg/kg/d) or the ECE-NEP inhibitor CGS26303 (10 mg/kg/d) were administered alone or in combination (subcutaneously for 28 days starting 7 days after coronary ligation). ACE-ECE-NEP inhibition reduced blood pressure more markedly than ACE or ECE-NEP inhibition. All treatments increased cardiac output to the same extent, but ACE-ECE-NEP inhibition reduced LV diameter and LV end-diastolic pressure more markedly than ACE or ECE-NEP inhibition. The reduction of LV weight and collagen accumulation in the "viable" myocardium was most pronounced after ACE-ECE-NEP inhibition. These results, obtained in experimental CHF, illustrate a further improvement of LV hemodynamics and structure after ACE-ECE-NEP inhibition compared with either ACE or ECE-NEP inhibition, but whether this is associated with a further improvement of exercise tolerance and/or survival remains to be determined.

  2. Equol inhibits growth, induces atresia, and inhibits steroidogenesis of mouse antral follicles in vitro

    PubMed Central

    Mahalingam, Sharada; Gao, Liying; Gonnering, Marni; Helferich, William; Flaws, Jodi A.

    2016-01-01

    Equol is a non-steroidal estrogen metabolite produced by microbial conversion of daidzein, a major soy isoflavone, in the gut of some humans and many animal species. Isoflavones and their metabolites can affect endogenous estradiol production, action, and metabolism, potentially influencing ovarian follicle function. However, no studies have examined the effects of equol on intact ovarian antral follicles, which are responsible for sex steroid synthesis and further development into ovulatory follicles. Thus, the present study tested the hypothesis that equol inhibits antral follicle growth, increases follicle atresia, and inhibits steroidogenesis in the adult mouse ovary. To test this hypothesis, antral follicles isolated from adult CD-1 mice were cultured with vehicle control (dimethyl sulfoxide; DMSO) or equol (600 nM, 6 μM, 36 μM, 100 μM) for 48 and 96 h. Every 24 h, follicle diameters were measured to monitor growth. At 48 and 96 h, the culture medium was subjected to measurement of hormone levels, and the cultured follicles were subjected to gene expression analysis. Additionally, follicles were histologically evaluated for signs of atresia after 96 h of culture. The results indicate that equol (100 μM) inhibited follicle growth, altered the mRNA levels of bcl2-associated X protein and B cell leukemia/lymphoma 2, and induced follicle atresia. Further, equol decreased the levels of estradiol, testosterone, androstenedione, and progesterone, and it decreased mRNA levels of cholesterol side-chain cleavage, steroid 17-α-hydroxalase, and aromatase. Collectively, these data indicate that equol inhibits growth, increases atresia, and inhibits steroidogenesis of cultured mouse antral follicles. PMID:26876617

  3. Doxycycline inhibits leukemic cell migration via inhibition of matrix metalloproteinases and phosphorylation of focal adhesion kinase.

    PubMed

    Wang, Chunhuai; Xiang, Ru; Zhang, Xiangzhong; Chen, Yunxian

    2015-09-01

    Doxycycline, a tetracycline-based antibiotic, has been reported to attenuate melanoma cell migration through inhibiting the focal adhesion kinase (FAK) signaling pathway. However, it remains to be elucidated whether doxycycline exerts this effect on leukemia cell migration. The present study aimed to examine the role of doxycycline in leukemia cell migration. The invasion capacities of the human leukemia cell lines KG1a (acute myelogenous leukemia) and K562 (chronic myelogenous leukemia) were evaluated using Matrigel® matrix‑coated Transwell® chamber assays; leukemic cell lines treated with doxycycline (1 µg/ml) or anti‑β1‑integrin antibodies were added to the upper chamber, while untreated cells were included as controls. Reverse transcription quantitative polymerase chain reaction was performed in order to further understand the influence of doxycycline treatment on the expression of FAK and gelatinases in the KG1a and K562 leukemic cell lines. In addition, FAK protein expression and phosphorylation were determined using western blot analysis in order to investigate the mechanism by which doxycycline inhibited leukemic cell migration. The results revealed that doxycycline treatment significantly attenuated the migration of KG1a and K562 cells, which was demonstrated to be associated with inhibition of the expression and phosphorylation of FAK. In addition, doxycycline treatment inhibited matrix metalloproteinase (MMP)‑2 and MMP‑9 expression. Furthermore, incubation with blocking anti‑β1‑integrin antibodies had an analogous inhibitory effect on leukemic cell migration to that of doxycycline. In conclusion, the results of the present study suggested that doxycycline attenuated leukemic cell migration through inhibiting the FAK signaling pathway. Therefore, doxycycline may have potential for use as a novel strategy for the treatment of leukemia.

  4. Neural and behavioral mechanisms of proactive and reactive inhibition.

    PubMed

    Meyer, Heidi C; Bucci, David J

    2016-10-01

    Response inhibition is an important component of adaptive behavior. Substantial prior research has focused on reactive inhibition, which refers to the cessation of a motor response that is already in progress. More recently, a growing number of studies have begun to examine mechanisms underlying proactive inhibition, whereby preparatory processes result in a response being withheld before it is initiated. It has become apparent that proactive inhibition is an essential component of the overall ability to regulate behavior and has implications for the success of reactive inhibition. Moreover, successful inhibition relies on learning the meaning of specific environmental cues that signal when a behavioral response should be withheld. Proactive inhibitory control is mediated by stopping goals, which reflect the desired outcome of inhibition and include information about how and when inhibition should be implemented. However, little is known about the circuits and cellular processes that encode and represent features in the environment that indicate the necessity for proactive inhibition or how these representations are implemented in response inhibition. In this article, we will review the brain circuits and systems involved in implementing inhibitory control through both reactive and proactive mechanisms. We also comment on possible cellular mechanisms that may contribute to inhibitory control processes, noting that substantial further research is necessary in this regard. Furthermore, we will outline a number of ways in which the temporal dynamics underlying the generation of the proactive inhibitory signal may be particularly important for parsing out the neurobiological correlates that contribute to the learning processes underlying various aspects of inhibitory control.

  5. Comparison of Alcohol Impairment of Behavioral and Attentional Inhibition

    PubMed Central

    Weafer, Jessica; Fillmore, Mark T.

    2012-01-01

    Background Despite the wealth of studies demonstrating the impairing effects of alcohol on behavioral inhibition, less is known regarding effects of the drug on attentional inhibition (i.e., the ability to ignore distracting stimuli in the environment in order to focus attention on relevant information). The current study examined alcohol impairment of both behavioral and attentional inhibition, as well as potential associations between the two mechanisms of inhibitory control. Methods Men (n = 27) and women (n = 21) performed a measure of behavioral inhibition (cued go/no-go task) and a measure of attentional inhibition (delayed ocular return task) following three doses of alcohol: 0.65 g/kg, 0.45 g/kg, and 0.0 g/kg (placebo). Results Alcohol impaired both behavioral and attentional inhibition relative to placebo; however, correlational analyses revealed no associations between measures of behavioral and attentional inhibition following any dose. Additionally, men committed more inhibitory failures on the behavioral inhibition task, whereas women committed more inhibitory failures on the attentional inhibition task. Conclusions These findings suggest that behavioral and attentional inhibition are equally sensitive to the impairing effects of alcohol, yet represent distinct components of inhibitory control. Additionally, the observed gender differences in control of behavior and attention could have important implications regarding negative consequences associated with alcohol-induced disinhibition in men and women. PMID:22673197

  6. Auxin inhibition of ripening in bartlett pears.

    PubMed

    Frenkel, C; Dyck, R

    1973-01-01

    The effect of indoleacetic acid and 2,4-dichlorophenoxyacetic acid on the ripening of intact mature-green pears (Pyrus communis var. Bartlett) was investigated using a vacuum infiltration technique.The effects of indoleacetic acid and 2,4-dichlorophenoxyacetic acid at concentrations of 0.01, 0.1, and 1.0 mm each were studied on softening, degreening, and on ethylene and CO(2) evolution. Softening and degreening were inhibited increasingly in response to increased concentrations of indoleacetic acid. This inhibitory property was amplified by 2,4-dichlorophenoxyacetic acid at concentrations comparable to those of indoleacetic acid. Application of the auxins also prevented the climacteric rise in respiration, but stimulated ethylene synthesis. Despite the presence of elevated ethylene levels, the inhibitory auxin effect was predominant.It is proposed that endogenous auxins in fruit represent a resistance factor in ripening and must be inactivated before ripening can occur.

  7. ACAT inhibition and amyloid beta reduction.

    PubMed

    Bhattacharyya, Raja; Kovacs, Dora M

    2010-08-01

    Alzheimer's disease (AD) is a devastating neurodegenerative disorder. Accumulation and deposition of the beta-amyloid (Abeta) peptide generated from its larger amyloid precursor protein (APP) is one of the pathophysiological hallmarks of AD. Intracellular cholesterol was shown to regulate Abeta production. Recent genetic and biochemical studies indicate that not only the amount, but also the distribution of intracellular cholesterol is critical to regulate Abeta generation. Acyl-coenzyme A: cholesterol acyl-transferase (ACAT) is a family of enzymes that regulates the cellular distribution of cholesterol by converting membrane cholesterol into hydrophobic cholesteryl esters for cholesterol storage and transport. Using pharmacological inhibitors and transgenic animal models, we and others have identified ACAT1 as a potential therapeutic target to lower Abeta generation and accumulation. Here we discuss data focusing on ACAT inhibition as an effective strategy for the prevention and treatment of AD.

  8. Inhibition of cyclodextrins on α-galactosidase.

    PubMed

    Yao, Di; Zhu, Zhenzhou; Cai, Hongyan; Chen, Xuan; Sun, Wei; Barba, Francisco J; Li, Fang; Shen, Wangyang; Ding, Wenping

    2017-02-15

    This work successfully investigated the effects of different influential factors and hydrophobic cavities of cyclodextrins (CDs) on α-galactosidase (α-Gal) by detecting α-Gal activity. The highest inhibitory concentration of three kinds of CDs (α-, β-, and γ-CD) on α-Gal was 10mM. Moreover, the highest inhibition of α-Gal was obtained under the following conditions: reaction time of 90min, temperature of 30°C, and pH 6.0. Compared with other CDs, β-CD showed more ability to interact with α-Gal due to its appropriate cavity geometric dimensions. From circular dichroism and nuclear magnetic resonance it was observed that β-CD changed the secondary structure of α-Gal and formed a hydrogen bond with this enzyme.

  9. Inhibition of bleach-induced luminol chemiluminescence.

    PubMed

    Kent, Erina J M; Elliot, Douglas A; Miskelly, Gordon M

    2003-01-01

    The luminol chemiluminescence presumptive test for blood is based on the mild peroxidase activity of hemoglobin in basic peroxide solution. However, this test is subject to interference by strong oxidants, certain transition metal ions, and true peroxidases. This paper reports methods for reducing the interference caused by hypochlorite-containing bleaches. Amines such as 1,2-diaminoethane react rapidly with hypochlorite without interfering significantly with the hemoglobin-catalyzed oxidation. Thus, addition of 0.1 mol/L 1,2-diaminoethane to a standard luminol-peroxide spray lead to almost complete inhibition of hypochlorite-induced chemiluminescence while satisfactory chemiluminescence was still observed from bloodstains. If time allows, an alternative method for reducing interference from hypochlorite bleach is to wait several days until the bloodstains have dried thoroughly, by which time the hypochlorite will have decomposed.

  10. Tooth brushing inhibits oral bacteria in dogs

    PubMed Central

    WATANABE, Kazuhiro; HAYASHI, Kotaro; KIJIMA, Saku; NONAKA, Chie; YAMAZOE, Kazuaki

    2015-01-01

    In this study, scaling, polishing and daily tooth brushing were performed in 20 beagle dogs, and the number of oral bacteria was determined using a bacterial counter. The dogs were randomized into the scaling (S), scaling + polishing (SP), scaling + tooth daily brushing (SB) and scaling + polishing + tooth daily brushing (SPB) groups. Samples were collected from the buccal surface of the maxillary fourth premolars of the dogs immediately after scaling and every week thereafter from weeks 1 to 8. Throughout the study, the number of bacteria was significantly lower in the SB and SPB groups compared with the S group. The findings suggest that daily tooth brushing inhibited oral bacterial growth in the dogs. PMID:25994486

  11. Inhibition of return: Twenty years after.

    PubMed

    Lupianez, Juan; Klein, Raymond M; Bartolomeo, Paolo

    2006-10-01

    When responding to a suddenly appearing stimulus, we are slower and/or less accurate when the stimulus occurs at the same location of a previous event than when it appears in a new location. This phenomenon, often referred to as inhibition of return (IOR), has fostered a huge amount of research in the last 20 years. In this selective review, which introduces a Special Issue of Cognitive Neuropsychology dedicated to IOR, we discuss some of the methods used for eliciting IOR and its boundary conditions. We also address its debated relationships with orienting of attention, succinctly review findings of altered IOR in normal elderly and neuropsychiatric patients, and present results concerning its possible neural bases. We conclude with an outline of the papers collected in this issue, which offer a more in-depth treatment of behavioural, neural, and theoretical issues related to IOR.

  12. Identification of enteroviruses by hemagglutination-inhibition.

    PubMed

    Kern, J; Rosen, L

    1966-05-01

    Kern, Jerome (Pacific Research Section, Honolulu, Hawaii), and Leon Rosen. Identification of enteroviruses by hemagglutination-inhibition. J. Bacteriol. 91:1936-1942. 1966.-Approximately 40% of a group of 906 enterovirus isolates cytopathic for monkey cell cultures were found to possess hemagglutinins for human erythrocytes when tested at temperatures of 4 and 37 C and at pH 5.8 and 7.3. The hemagglutinating isolates could be classified by relatively simple techniques into 18 serotypes. Four of these serotypes, echovirus type 24 and coxsackievirus B types 1, 5, and 6, had not previously been known to include hemagglutinating strains. One serotype, Toluca-3, represented a previously unrecognized enterovirus, and two other serotypes may also represent previously unrecognized enteroviruses.

  13. Tailoring elastase inhibition with synthetic peptides.

    PubMed

    Vasconcelos, Andreia; Azoia, Nuno G; Carvalho, Ana C; Gomes, Andreia C; Güebitz, Georg; Cavaco-Paulo, Artur

    2011-09-01

    Chronic wounds are the result of excessive amounts of tissue destructive proteases such as human neutrophil elastase (HNE). The high levels of this enzyme found on those types of wounds inactivate the endogenous inhibitor barrier thus, the search for new HNE inhibitors is required. This work presents two new HNE inhibitor peptides, which were synthesized based on the reactive-site loop of the Bowman-Birk inhibitor protein. The results obtained indicated that these new peptides are competitive inhibitors for HNE and, the inhibitory activity can be modulated by modifications introduced at the N- and C-terminal of the peptides. Furthermore, these peptides were also able to inhibit elastase from a human wound exudate while showing no cytotoxicity against human skin fibroblasts in vitro, greatly supporting their potential application in chronic wound treatment.

  14. Selective Raf Inhibition in Cancer Therapy

    PubMed Central

    Khazak, Vladimir; Astsaturov, Igor; Serebriiskii, Ilya G; Golemis, Erica A

    2009-01-01

    Over the past 5 years, the Raf kinase family has emerged as a promising target for protein-directed cancer therapy development. The goal of this review is to first provide a concise summary of the data validating Raf proteins as high-interest therapeutic targets. We then outline the mode of action of Raf kinases, emphasizing how Raf activities and protein interactions suggest specific approaches to inhibiting Raf. We then summarize the set of drugs, antisense reagents, and antibodies available or in development for therapeutically targeting Raf or Raf-related proteins, as well as current strategies combining these and other therapeutic agents. Finally, we discuss recent results from systems biology analyses that have the potential to increasingly guide the intelligent selection of combination therapies involving Raf-targeting agents and other therapeutics. PMID:18020980

  15. Selective Raf inhibition in cancer therapy.

    PubMed

    Khazak, Vladimir; Astsaturov, Igor; Serebriiskii, Ilya G; Golemis, Erica A

    2007-12-01

    Over the past 5 years, the Raf kinase family has emerged as a promising target for protein-directed cancer therapy development. The goal of this review is to first provide a concise summary of the data validating Raf proteins as high-interest therapeutic targets. The authors then outline the mode of action of Raf kinases, emphasizing how Raf activities and protein interactions suggest specific approaches to inhibiting Raf. The authors then summarize the set of drugs, antisense reagents and antibodies available or in development for therapeutically targeting Raf or Raf-related proteins, as well as existing strategies combining these and other therapeutic agents. Finally, the authors discuss recent results from systems biology analyses that have the potential to increasingly guide the intelligent selection of combination therapies involving Raf-targeting agents and other therapeutics.

  16. Inhibition of human papillomavirus expression using DNAzymes.

    PubMed

    Benítez-Hess, María Luisa; Reyes-Gutiérrez, Pablo; Alvarez-Salas, Luis Marat

    2011-01-01

    Deoxyribozymes (DXZs) are catalytic oligodeoxynucleotides capable of performing diverse functions including the specific cleavage of a target RNA. These molecules represent a new type of therapeutic oligonucleotides combining the efficiency of ribozymes and the intracellular endurance and simplicity of modified antisense oligonucleotides. Commonly used DXZs include the 8-17 and 10-23 motifs, which have been engineered to destroy disease-associated genes with remarkable efficiency. Targeting DXZs to disease-associated transcripts requires extensive biochemical testing to establish target RNA accessibility, catalytic efficiency, and nuclease sensibility. The usage of modified nucleotides to render nuclease-resistance DXZs must be counterweighted against deleterious consequences on catalytic activity. Further intracellular testing is required to establish the effect of microenvironmental conditions on DXZ activity and off-target issues. Application of modified DXZs to cervical cancer results in specific growth inhibition, cell death, and apoptosis. Thus, DXZs represent a highly effective antisense moiety with minimal secondary effects.

  17. Allosteric inhibition of HIV-1 integrase activity

    PubMed Central

    Engelman, Alan; Kessl, Jacques J.; Kvaratskhelia, Mamuka

    2013-01-01

    HIV-1 integrase is an important therapeutic target in the fight against HIV/AIDS. Integrase strand transfer inhibitors (INSTIs), which target the enzyme active site, have witnessed clinical success over the past 5 years, but the generation of drug resistance poses challenges to INSTI-based therapies moving forward. Integrase is a dynamic protein, and its ordered multimerization is critical to enzyme activity. The integrase tetramer, bound to viral DNA, interacts with host LEDGF/p75 protein to tether integration to active genes. Allosteric integrase inhibitors (ALLINIs) that compete with LEDGF/p75 for binding to integrase disrupt integrase assembly with viral DNA and allosterically inhibit enzyme function. ALLINIs display steep dose response curves and synergize with INSTIs ex vivo, highlighting this novel inhibitor class for clinical development. PMID:23647983

  18. Novel Polyanions Inhibiting Replication of Influenza Viruses

    PubMed Central

    Ciejka, Justyna; Milewska, Aleksandra; Wytrwal, Magdalena; Wojarski, Jacek; Golda, Anna; Ochman, Marek; Nowakowska, Maria

    2016-01-01

    Novel sulfonated derivatives of poly(allylamine hydrochloride) (NSPAHs) and N-sulfonated chitosan (NSCH) have been synthesized, and their activity against influenza A and B viruses has been studied and compared with that of a series of carrageenans, marine polysaccharides of well-documented anti-influenza activity. NSPAHs were found to be nontoxic and very soluble in water, in contrast to gel-forming and thus generally poorly soluble carrageenans. In vitro and ex vivo studies using susceptible cells (Madin-Darby canine kidney epithelial cells and fully differentiated human airway epithelial cultures) demonstrated the antiviral effectiveness of NSPAHs. The activity of NSPAHs was proportional to the molecular mass of the chain and the degree of substitution of amino groups with sulfonate groups. Mechanistic studies showed that the NSPAHs and carrageenans inhibit influenza A and B virus assembly in the cell. PMID:26729490

  19. Selecting patients for KIT inhibition in melanoma.

    PubMed

    Carvajal, Richard D; Hamid, Omid; Antonescu, Cristina R

    2014-01-01

    For many years, melanoma has been regarded as a single disease in terms of therapeutic considerations. The more recent identification of multiple molecular mechanisms underlying the development, progression, and prognosis of melanoma has led to a new paradigm for the management of this disease, has created new therapeutic opportunities, and has led to improved clinical outcomes. Such advances, however, are dependent upon methods that can reproducibly identify key molecular alterations within an individual tumor, define clinically relevant genetic subgroups of disease, and permit improved patient selection for targeted therapies.Melanomas harboring genetic alterations of KIT have been demonstrated to constitute one such molecular subgroup of disease. In this chapter, we will discuss the biology of KIT in melanoma, review the rationale for and clinical data regarding KIT inhibition in melanomas harboring activating alterations of KIT, propose guidelines for the selection of patients for KIT inhibitor therapy, and, finally, present laboratory methods for KIT assessment in melanoma.

  20. Inhibition and Mechanism of HDAC8 Revisited

    PubMed Central

    2015-01-01

    Histone deacetylases (HDACs) have found intense interest as drug targets for a variety of diseases, but there is disagreement about basic aspects of the inhibition and mechanism of HDACs. QM/MM calculations of HDAC8 including a large QM region provide a model that is consistent with the available crystal structures and structure–activity relationships of different HDAC inhibitors. The calculations support a spontaneous proton transfer from a hydroxamic acid to an active site histidine upon binding to the zinc. The role of the H142/D176 catalytic dyad as the general base of the reaction is elucidated. The reasons for the disagreements between previous proposals are discussed. The results provide detailed insights into the unique mechanism of HDACs, including the role of the two catalytic dyads and function of the potassium near the active site. They also have important implications for the design of novel inhibitors for a number of HDACs such as the class IIa HDACs. PMID:25060069

  1. Structural basis of kynurenine 3-monooxygenase inhibition

    PubMed Central

    Amaral, Marta; Levy, Colin; Heyes, Derren J.; Lafite, Pierre; Outeiro, Tiago F.; Giorgini, Flaviano; Leys, David; Scrutton, Nigel S.

    2013-01-01

    Inhibition of kynurenine 3-monooxygenase (KMO), an enzyme in the eukaryotic tryptophan catabolic pathway (i.e. kynurenine pathway), leads to amelioration of Huntington’s disease-relevant phenotypes in yeast, fruit fly, and mouse models1–5, as well as a mouse model of Alzheimer’s disease3. KMO is a FAD-dependent monooxygenase, and is located in the outer mitochondrial membrane where it converts L-kynurenine to 3-hydroxykynurenine. Perturbations in the levels of kynurenine pathway metabolites have been linked to the pathogenesis of a spectrum of brain disorders6, as well as cancer7,8, and several peripheral inflammatory conditions9. Despite the importance of KMO as a target for neurodegenerative disease, the molecular basis of KMO inhibition by available lead compounds has remained hitherto unknown. Here we report the first crystal structure of KMO, in the free form and in complex with the tight-binding inhibitor UPF 648. UPF 648 binds close to the FAD cofactor and perturbs the local active site structure, preventing productive binding of the substrate kynurenine. Functional assays and targeted mutagenesis revealed that the active site architecture and UPF 648 binding are essentially identical in human KMO, validating the yeast KMO:UPF 648 structure as a template for structure-based drug design. This will inform the search for new KMO inhibitors that are able to cross the blood-brain barrier in targeted therapies against neurodegenerative diseases such as Huntington’s, Alzheimer’s, and Parkinson’s diseases. PMID:23575632

  2. Inhibition of morphine metabolism by ketamine.

    PubMed

    Qi, Xiaoxin; Evans, Allan M; Wang, Jiping; Miners, John O; Upton, Richard N; Milne, Robert W

    2010-05-01

    Clinical observation of a synergistic effect of ketamine on morphine analgesia remains controversial. Although a pharmacodynamic basis for an interaction has been explored in animal and clinical studies, the possibility of a pharmacokinetic mechanism has not been investigated. Whereas both morphine and morphine-6-glucuronide are effective analgesics, morphine-3-glucuronide (M3G) lacks activity. Thus, changes in the metabolism and disposition of morphine may result in an altered response. First, we investigated the interaction between morphine and ketamine in the isolated perfused rat liver preparation. The clearance of morphine was decreased from 16.8 +/- 4.6 ml/min in the control period to 7.7 +/- 2.8 ml/min in the ketamine-treatment period, with the formation clearance of M3G decreasing from 8.0 +/- 4.1 ml/min to 2.1 +/- 1.1 ml/min. Fractional conversion of morphine to M3G was significantly decreased from 0.46 +/- 0.17 in the control period to 0.28 +/- 0.14 upon the addition of ketamine. The possible mechanism of the interaction was further investigated in vitro with rat liver microsomes as the enzyme source. The formation of M3G followed single-enzyme Michaelis-Menten kinetics, with a mean apparent K(m) of 2.18 +/- 0.45 mM and V(max) of 8.67 +/- 0.59 nmol/min/mg. Ketamine inhibited morphine 3-glucuronidation noncompetitively, with a mean K(i) value of 33.3 +/- 7.9 microM. The results demonstrate that ketamine inhibits the glucuronidation of morphine in a rat model.

  3. Protein Fibrillation Lag Times During Kinetic Inhibition

    PubMed Central

    Pagano, Rodrigo S.; López Medus, Máximo; Gómez, Gabriela E.; Couto, Paula M.; Labanda, María S.; Landolfo, Lucas; D’Alessio, Cecilia; Caramelo, Julio J.

    2014-01-01

    Protein aggregation is linked to more than 30 human pathologies, including Alzheimer’s and Parkinson’s diseases. Since small oligomers that form at the beginning of the fibrillation process probably are the most toxic elements, therapeutic strategies involving fibril fragmentation could be detrimental. An alternative approach, named kinetic inhibition, aims to prevent fibril formation by using small ligands that stabilize the parent protein. The factors that govern fibrillation lag times during kinetic inhibition are largely unknown, notwithstanding their importance for designing effective long-term therapies. Inhibitor-bound species are not likely to be incorporated into the core of mature fibrils, although their presence could alter the kinetics of the fibrillation process. For instance, inhibitor-bound species may act as capping elements that impair the nucleation process and/or fibril growth. Here, we address this issue by studying the effect of two natural inhibitors on the fibrillation behavior of lysozyme at neutral pH. We analyzed a set of 79 fibrillation curves obtained in lysozyme alone and a set of 37 obtained in the presence of inhibitors. We calculated the concentrations of the relevant species at the beginning of the curves using the inhibitor-binding constants measured under the same experimental conditions. We found that inhibitor-bound protein species do not affect fibrillation onset times, which are mainly determined by the concentration of unbound protein species present in equilibrium. In this system, knowledge of the fibrillation kinetics and inhibitor affinities suffices to predict the effect of kinetic inhibitors on fibrillation lag times. In addition, we developed a new methodology to better estimate fibrillation lag times from experimental curves. PMID:25099810

  4. Inhibition of Quorum Sensing in Staphylococcus spp.

    PubMed

    Brackman, Gilles; Coenye, Tom

    2015-01-01

    The Gram-positive, facultative anaerobic coccus-shaped bacteria of the genus Staphylococcus are among the most important causative agents of acute and chronic bacterial infections in humans as well as in animals. Treatment of Staphylococcus infections has become increasingly challenging due to the growing problem of antibiotic resistance. For this reason innovative antimicrobials with novel targets and modes of action are needed. Since the discovery that QS is used by Staphylococcus spp. to coordinate the expression of several genes involved in virulence, biofilm formation and pathogenicity, QS inhibition has gained increasing attention as an alternative anti-pathogenic strategy. A major advantage compared with antibiotic therapy is that QSIs are used in concentrations that do not affect bacterial growth. For this reason, it is expected that these compounds would exert less pressure towards the development of resistance. However, some important points still need to be addressed. Although several inhibitors have proven to be active antipathogenic agents in vitro and in several in vivo models, it is still unknown whether these compounds will also be useful in humans. Furthermore, several fundamental mechanisms by which the different QS systems in Staphylococcus spp. exert their regulatory functions and how they are inhibited by QSIs are still poorly understood. In order to achieve real-life applications with QSIs, these challenges should be addressed and more research will be needed. In this article, we will discuss the different QS systems present in Staphylococcus spp., how they are used to control virulence and biofilm formation and how they can be blocked.

  5. Nitric oxide synthases: structure, function and inhibition.

    PubMed Central

    Alderton, W K; Cooper, C E; Knowles, R G

    2001-01-01

    This review concentrates on advances in nitric oxide synthase (NOS) structure, function and inhibition made in the last seven years, during which time substantial advances have been made in our understanding of this enzyme family. There is now information on the enzyme structure at all levels from primary (amino acid sequence) to quaternary (dimerization, association with other proteins) structure. The crystal structures of the oxygenase domains of inducible NOS (iNOS) and vascular endothelial NOS (eNOS) allow us to interpret other information in the context of this important part of the enzyme, with its binding sites for iron protoporphyrin IX (haem), biopterin, L-arginine, and the many inhibitors which interact with them. The exact nature of the NOS reaction, its mechanism and its products continue to be sources of controversy. The role of the biopterin cofactor is now becoming clearer, with emerging data implicating one-electron redox cycling as well as the multiple allosteric effects on enzyme activity. Regulation of the NOSs has been described at all levels from gene transcription to covalent modification and allosteric regulation of the enzyme itself. A wide range of NOS inhibitors have been discussed, interacting with the enzyme in diverse ways in terms of site and mechanism of inhibition, time-dependence and selectivity for individual isoforms, although there are many pitfalls and misunderstandings of these aspects. Highly selective inhibitors of iNOS versus eNOS and neuronal NOS have been identified and some of these have potential in the treatment of a range of inflammatory and other conditions in which iNOS has been implicated. PMID:11463332

  6. Milk inhibits the biological activity of ricin.

    PubMed

    Rasooly, Reuven; He, Xiaohua; Friedman, Mendel

    2012-08-10

    Ricin is a highly toxic protein produced by the castor plant Ricinus communis. The toxin is relatively easy to isolate and can be used as a biological weapon. There is great interest in identifying effective inhibitors for ricin. In this study, we demonstrated by three independent assays that a component of reconstituted powdered milk has a high binding affinity to ricin. We discovered that milk can competitively bind to and reduce the amount of toxin available to asialofetuin type II, which is used as a model to study the binding of ricin to galactose cell-surface receptors. Milk also removes ricin bound to the microtiter plate. In parallel experiments, we demonstrated by activity assay and by immuno-PCR that milk can bind competitively to 1 ng/ml ricin, reducing the amount of toxin uptake by the cells, and thus inhibit the biological activity of ricin. The inhibitory effect of milk on ricin activity in Vero cells was at the same level as by anti-ricin antibodies. We also found that (a) milk did not inhibit ricin at concentrations of 10 or 100 ng/ml; (b) autoclaving 10 and 100 ng/ml ricin in DMEM at 121 °C for 30 min completely abolished activity; and (c) milk did not affect the activity of another ribosome inactivating protein, Shiga toxin type 2 (Stx2), produced by pathogenic Escherichia coli O157:H7. Unlike ricin, which is internalized into the cells via a galactose-binding site, Stx2 is internalized through the cell surface receptor glycolipid globotriasylceramides Gb3 and Gb4. These observations suggest that ricin toxicity may possibly be reduced at room temperature by a widely consumed natural liquid food.

  7. Selective inhibition of human acetylcholinesterase by xanthine derivatives: in vitro inhibition and molecular modeling investigations.

    PubMed

    Mohamed, Tarek; Osman, Wesseem; Tin, Gary; Rao, Praveen P N

    2013-08-01

    The commonly used beverage and psychostimulant caffeine is known to inhibit human acetylcholinesterase enzyme. This pharmacological activity of caffeine is partly responsible for its cognition enhancing properties. However, the exact mechanisms of its binding to human cholinesterases (acetyl and butyrylcholinesterase; hAChE and hBuChE) are not well known. In this study, we investigated the cholinesterase inhibition by the xanthine derivatives caffeine, pentoxifylline, and propentofylline. Among them, propentofylline was the most potent AChE inhibitor (hAChE IC₅₀=6.40 μM). The hAChE inhibitory potency was of the order: caffeine (hAChE IC₅₀=7.25 μM)inhibition of hAChE with no inhibition of hBuChE (IC₅₀>50 μM) relative to the reference agent donepezil (hBuChE IC₅₀=13.60 μM). Molecular modeling investigations indicate that caffeine binds primarily in the catalytic site (Ser203, Glu334 and His447) region of hAChE whereas pentoxifylline and propentofylline are able to bind to both the catalytic site and peripheral anionic site due to their increased bulk/size, thereby exhibiting superior AChE inhibition relative to caffeine. In contrast, their lack of hBuChE inhibition is due to a larger binding site and lack of key aromatic amino acids. In summary, our study has important implications in the development of novel caffeine derivatives as selective AChE inhibitors with potential application as cognitive enhancers and to treat various forms of dementia.

  8. Task Inhibition and Response Inhibition in Older vs. Younger Adults: A Diffusion Model Analysis

    PubMed Central

    Schuch, Stefanie

    2016-01-01

    Differences in inhibitory ability between older (64–79 years, N = 24) and younger adults (18–26 years, N = 24) were investigated using a diffusion model analysis. Participants performed a task-switching paradigm that allows assessing n−2 task repetition costs, reflecting inhibitory control on the level of tasks, as well as n−1 response-repetition costs, reflecting inhibitory control on the level of responses. N−2 task repetition costs were of similar size in both age groups. Diffusion model analysis revealed that for both younger and older adults, drift rate parameters were smaller in the inhibition condition relative to the control condition, consistent with the idea that persisting task inhibition slows down response selection. Moreover, there was preliminary evidence for task inhibition effects in threshold separation and non-decision time in the older, but not the younger adults, suggesting that older adults might apply different strategies when dealing with persisting task inhibition. N−1 response-repetition costs in mean RT were larger in older than younger adults, but in mean error rates tended to be larger in younger than older adults. Diffusion-model analysis revealed longer non-decision times in response repetitions than response switches in both age groups, consistent with the idea that motor processes take longer in response repetitions than response switches due to persisting response inhibition of a previously executed response. The data also revealed age-related differences in overall performance: Older adults responded more slowly and more accurately than young adults, which was reflected by a higher threshold separation parameter in diffusion model analysis. Moreover, older adults showed larger non-decision times and higher variability in non-decision time than young adults, possibly reflecting slower and more variable motor processes. In contrast, overall drift rate did not differ between older and younger adults. Taken together

  9. Reconciling the role of serotonin in behavioral inhibition and aversion: acute tryptophan depletion abolishes punishment-induced inhibition in humans.

    PubMed

    Crockett, Molly J; Clark, Luke; Robbins, Trevor W

    2009-09-23

    The neuromodulator serotonin has been implicated in a large number of affective and executive functions, but its precise contribution to motivation remains unclear. One influential hypothesis has implicated serotonin in aversive processing; another has proposed a more general role for serotonin in behavioral inhibition. Because behavioral inhibition is a prepotent reaction to aversive outcomes, it has been a challenge to reconcile these two accounts. Here, we show that serotonin is critical for punishment-induced inhibition but not overall motor response inhibition or reporting aversive outcomes. We used acute tryptophan depletion to temporarily lower brain serotonin in healthy human volunteers as they completed a novel task designed to obtain separate measures of motor response inhibition, punishment-induced inhibition, and sensitivity to aversive outcomes. After a placebo treatment, participants were slower to respond under punishment conditions compared with reward conditions. Tryptophan depletion abolished this punishment-induced inhibition without affecting overall motor response inhibition or the ability to adjust response bias in line with punishment contingencies. The magnitude of reduction in punishment-induced inhibition depended on the degree to which tryptophan depletion reduced plasma tryptophan levels. These findings extend and clarify previous research on the role of serotonin in aversive processing and behavioral inhibition and fit with current theorizing on the involvement of serotonin in predicting aversive outcomes.

  10. Inhibition of MAO by fractions and constituents of hypericum extract.

    PubMed

    Bladt, S; Wagner, H

    1994-10-01

    The inhibition of monoamine oxidase (MAO) by six fractions from hypericum extract and three characteristic constituents (as pure substances) were analyzed in vitro and ex vivo to study the antidepressive mechanism of action. Rat brain homogenates were used as the in vitro model, while the ex vivo analysis was performed after intraperitoneal application of the test substances to albino rats. Massive inhibition of MAO-A could be shown with the total extract and all fractions only at the concentration of 10(-3) mol/L. At 10(-4) mol/L, one fraction rich in flavonoides showed an inhibition of 39%, and all other fractions demonstrated less than 25% inhibition. Using pure hypericin as well as in all ex vivo experiments, no relevant inhibiting effects could be shown. From the results it can be concluded that the clinically proven antidepressive effect of hypericum extract cannot be explained in terms of MAO inhibition.

  11. Molecular mechanisms of DNA repair inhibition by caffeine

    SciTech Connect

    Selby, C.P.; Sancar, A. )

    1990-05-01

    Caffeine potentiates the mutagenic and lethal effects of genotoxic agents. It is thought that this is due, at least in some organisms, to inhibition of DNA repair. However, direct evidence for inhibition of repair enzymes has been lacking. Using purified Escherichia coli DNA photolyase and (A)BC excinuclease, we show that the drug inhibits photoreactivation and nucleotide excision repair by two different mechanisms. Caffeine inhibits photoreactivation by interfering with the specific binding of photolyase to damaged DNA, and it inhibits nucleotide excision repair by promoting nonspecific binding of the damage-recognition subunit, UvrA, of (A)BC excinuclease. A number of other intercalators, including acriflavin and ethidium bromide, appear to inhibit the excinuclease by a similar mechanism--that is, by trapping the UvrA subunit in nonproductive complexes on undamaged DNA.

  12. Engineered kinesin motor proteins amenable to small-molecule inhibition

    PubMed Central

    Engelke, Martin F.; Winding, Michael; Yue, Yang; Shastry, Shankar; Teloni, Federico; Reddy, Sanjay; Blasius, T. Lynne; Soppina, Pushpanjali; Hancock, William O.; Gelfand, Vladimir I.; Verhey, Kristen J.

    2016-01-01

    The human genome encodes 45 kinesin motor proteins that drive cell division, cell motility, intracellular trafficking and ciliary function. Determining the cellular function of each kinesin would benefit from specific small-molecule inhibitors. However, screens have yielded only a few specific inhibitors. Here we present a novel chemical-genetic approach to engineer kinesin motors that can carry out the function of the wild-type motor yet can also be efficiently inhibited by small, cell-permeable molecules. Using kinesin-1 as a prototype, we develop two independent strategies to generate inhibitable motors, and characterize the resulting inhibition in single-molecule assays and in cells. We further apply these two strategies to create analogously inhibitable kinesin-3 motors. These inhibitable motors will be of great utility to study the functions of specific kinesins in a dynamic manner in cells and animals. Furthermore, these strategies can be used to generate inhibitable versions of any motor protein of interest. PMID:27045608

  13. Firing regulation of fast-spiking interneurons by autaptic inhibition

    NASA Astrophysics Data System (ADS)

    Guo, Daqing; Chen, Mingming; Perc, Matjaž; Wu, Shengdun; Xia, Chuan; Zhang, Yangsong; Xu, Peng; Xia, Yang; Yao, Dezhong

    2016-05-01

    Fast-spiking (FS) interneurons in the brain are self-innervated by powerful inhibitory GABAergic autaptic connections. By computational modelling, we investigate how autaptic inhibition regulates the firing response of such interneurons. Our results indicate that autaptic inhibition both boosts the current threshold for action potential generation and modulates the input-output gain of FS interneurons. The autaptic transmission delay is identified as a key parameter that controls the firing patterns and determines multistability regions of FS interneurons. Furthermore, we observe that neuronal noise influences the firing regulation of FS interneurons by autaptic inhibition and extends their dynamic range for encoding inputs. Importantly, autaptic inhibition modulates noise-induced irregular firing of FS interneurons, such that coherent firing appears at an optimal autaptic inhibition level. Our results reveal the functional roles of autaptic inhibition in taming the firing dynamics of FS interneurons.

  14. Inhibition of MAO and COMT by hypericum extracts and hypericin.

    PubMed

    Thiede, H M; Walper, A

    1994-10-01

    The influence of hypericin, hypericum total extract, and hypericum fractions on the activity of MAO and COMT, prepared in vitro from pork liver, were investigated in several concentration steps. An inhibition of MAO could be shown in the following concentrations (extract correlated to a mean molecular value of 500): hypericin to 10(-3) mol/L, hypericum total extract to 10(-4) mol/L, one extract fraction up to 10(-5). A COMT inhibition could not be shown for hypericin, with hypericum extract to 10(-4) mol/L and with two extract fractions also up to 10(-4) mol/L. The MAO inhibiting fraction contained hypericins as well as flavonols, the COMT-inhibition fraction being mainly flavonols and xanthones. The concentrations of inhibition shown might not be sufficient to explain the clinically proven antidepressive effect of hypericum particularl