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1

Quercetin inhibits degranulation and superoxide generation in PMA stimulated neutrophils  

PubMed Central

Activated neutrophils represent the main source of myeloperoxidase (MPO), superoxide (SO) and subsequently derived oxygen metabolites. They have important microbicidal activities, however in inflammatory conditions they may secondarily attack surrounding tissues. Overproduction of reactive oxygen species, prolonged or excessive liberation of MPO and other effective yet also toxic substances from neutrophils may participate in disturbed apoptosis, intensify the inflammatory processes and result in serious human diseases. The inhibitory effect of quercetin on PMA stimulated SO generation in isolated human neutrophils was found to be dose-dependent, without affecting the activity of intact isolated neutrophils. At comparable conditions, quercetin was more potent in inhibiting MPO release than SO generation. Our results indicate that quercetin could support resolution of inflammation through decreased activity of neutrophils, i.e. respiratory burst and degranulation. PMID:23118592

Ma?I?ková, Tatiana; Sviteková, Klára; Nosá?, Radomír

2012-01-01

2

Inhibition of human neutrophil degranulation by transforming growth factor-?1  

PubMed Central

Neutrophils enter tissues including the uterus and are found in the endometrium in increased numbers prior to menses. In this environment, they are exposed to transforming growth factor (TGF)-?1 produced by endometrial stromal and epithelial cells. We observed that incubation of neutrophils in vitro with TGF-?1 at 1 pg/ml significantly reduced their secretion of lactoferrin in response to lipopolysaccharide (LPS). This effect was achieved with as little as 15 min of pretreatment with TGF-?1. Inhibition of lactoferrin release by TGF-?1 was observed irrespective of whether neutrophils were stimulated by ligands for Toll-like receptor (TLR)-2, TLR-4 or FPR, the G protein-coupled receptor for formylated peptides. Inhibition by TGF-?1 was negated by SB-431542, a small molecule inhibitor that specifically blocks the kinase activity of the type I TGF-? receptor (ALK5) In contrast to lactoferrin release, another important neutrophil function, interleukin (IL)-8 driven chemotaxis, was not affected by TGF-?1 at 1 pg/ml or 100 pg/ml. We conclude that in tissues of the female reproductive tract, TGF-?1 inhibition of neutrophil degranulation may prevent these cells from initiating an inflammatory response or releasing degradative enzymes that could potentially damage the oocyte or fetus. PMID:17403059

Shen, L; Smith, J M; Shen, Z; Eriksson, M; Sentman, C; Wira, C R

2007-01-01

3

Inhibition of weak-affinity epitope-IgE interactions prevents mast cell degranulation  

PubMed Central

Development of specific inhibitors of allergy has had limited success, in part, owing to a lack of experimental models that reflect the complexity of allergen-IgE interactions. We designed a heterotetravalent allergen (HtTA) system, which reflects epitope heterogeneity, polyclonal response and number of immunodominant epitopes observed in natural allergens, thereby providing a physiologically relevant experimental model to study mast cell degranulation. The HtTA design revealed the importance of weak-affinity epitopes in allergy, particularly when presented with high-affinity epitopes. The effect of selective inhibition of weak-affinity epitope-IgE interactions was investigated with heterobivalent inhibitors (HBIs) designed to simultaneously target the antigen- and nucleotide-binding sites on the IgE Fab. HBI demonstrated enhanced avidity for the target IgE and was a potent inhibitor of degranulation in vitro and in vivo. These results demonstrate that partial inhibition of allergen-IgE interactions was sufficient to prevent mast cell degranulation, thus establishing the therapeutic potential of the HBI design. PMID:24096304

Handlogten, Michael W; Kiziltepe, Tanyel; Serezani, Ana P; Kaplan, Mark H; Bilgicer, Basar

2014-01-01

4

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

SciTech Connect

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.

Nishikawa, Hirofumi; Kitani, Seiichi, E-mail: drkitani@kaiyodai.ac.jp

2011-05-01

5

Anthocyanins, but not anthocyanidins, from bilberry (Vaccinium myrtillus L.) alleviate pruritus via inhibition of mast cell degranulation.  

PubMed

We have previously reported that bilberry anthocyanins exhibit an anti-pruritic effect in a mouse model of allergic contact dermatitis. It has been reported that anthocyanins are particularly sensitive to thermal treatment and are easily hydrolyzed to anthocyanidins when exposed to high temperatures. The objective of this study was to compare the anti-pruritic effect of anthocyanin-rich quality-controlled bilberry extract and anthocyanidin-rich degraded extract using a mouse model of allergic contact dermatitis. BALB/c mice with allergic contact dermatitis induced by 4 weeks of repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) were administered Bilberon-25 orally for 4 weeks after sensitization with TNCB. The effect of Bilberon-25 on pruritus was evaluated by measurement of scratching behavior. RBL-2H3 mast cells were used to investigate the effect of Bilberon-25 on degranulation in 48/80-stimulated mast cells. Compared with nonheated Bilberon-25, the proportion of anthocyanins in heated Bilberon-25 decreased, and the proportion of anthocyanidins was increased in heated-time dependent manner. Treatment with non-heated Bilberon-25 significantly attenuated the TNCB-induced increase in scratching behavior, whereas treatment with 2 h-heated Bilberon-25 did not. Moreover, 300 ?g/mL nonheated Bilberon-25 showed significant inhibition of degranulation in RBL-2H3 mast cells, whereas 2 h-heated Bilberon-25 had no effect at any concentration studied. It is assumed that the inhibitory effect of bilberry anthocyanins on pruritus might be mediated, at least in part, by its inhibitory effect on mast cell degranulation. In conclusion, the anthocyanin-rich but not anthocyanidin-rich bilberry extract may be a useful dietary supplement for skin diseases involving pruritic symptoms, such as chronic allergic contact dermatitis, atopic dermatitis, and rhinitis. PMID:23164040

Yamaura, Katsunori; Ishiwatari, Makiko; Yamamoto, Masao; Shimada, Maki; Bi, Yuanyuan; Ueno, Koichi

2012-12-01

6

Inhibition of T cell adhesion to extracellular matrix glycoproteins by histamine: a role for mast cell degranulation products.  

PubMed

Mast cells, which are capable of releasing a multitude of preformed and newly generated biological mediators and cytokines, are involved in various inflammatory processes. We studied whether histamine, a mast cell degranulation product, influences the adhesive interactions of T cells with extracellular matrix (ECM) glycoproteins, an event that occurs at sites of inflammation and is mediated primarily by virtue of cell-surface receptors of the beta 1-integrin subfamily. A prerequisite of lymphocyte-ECM interactions is activation of the cells, which modulates the affinity of the otherwise inactive integrins. Isolated rat CD4+ T cells were preincubated with histamine and activated with phorbol myristate acetate (PMA), and their ability to adhere to immobilized ECM components (fibronectin and laminin) was determined. Preincubation with histamine resulted in a 40-50% decrease in the adhesion of the CD4+ cells to both fibronectin or laminin. The notion that inhibition of T cell adhesion to ECM proteins by histamine-induced increase of the cells' intracellular levels of cAMP, thus interfering with calcium influx-associated events that occur during T cell activation, is supported by the finding that T cell adhesion was also abrogated by pharmacological inducers of cAMP. When the T cells were preincubated with supernatants of immunologically activated mast cells and then activated with PMA, a 40-50% inhibition of their adhesion to fibronectin or laminin was also observed. The inhibitory moiety present in the mast cell degranulation supernatants was resistant to heat (80 degrees C). Histamine exerted its suppressive effect on adhesion of T cells via their H2 receptors, as pretreatment with H2 antagonists abrogated the inhibitory effect. Thus, both purified histamine and mast cell-secreted histamine appear to be capable of affecting T cell interactions with ECM. PMID:7930946

Hershkoviz, R; Lider, O; Baram, D; Reshef, T; Miron, S; Mekori, Y A

1994-10-01

7

Inhibitory effects of edible marine algae extracts on degranulation of RBL-2H3 cells and mouse eosinophils  

Microsoft Academic Search

Inhibitory effects on degranulation of rat basophilic leukemia (RBL-2H3) cells and mouse eosinophils by marine algae extracts\\u000a were examined. More than 50% of the degranulation of RBL-2H3 cells was inhibited by water extracts of Ecklonia cava and Chrysymenia wrightii at a concentration of 100 ?g\\/mL. More than 50% of the degranulation of RBL-2H3 cells was inhibited by methanol extracts of

Takashi Kimiya; Kazuhiro Ohtani; Setsuko Satoh; Yuko Abe; Yoshihiko Ogita; Hirohisa Kawakita; Hideyuki Hamada; Yuko Konishi; Satoshi Kubota; Akira Tominaga

2008-01-01

8

Cardiovascular stress of photochemotherapy (PUVA)  

SciTech Connect

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.

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

1980-11-01

9

An evaluation of the preferences of patients with psoriasis between systemic PUVA and bath PUVA.  

PubMed

Psoralen plus ultraviolet A (PUVA) is a well established treatment for psoriasis. It comprises the use of psoralen as a photosensitiser, either orally or topically, before the patient is treated by irradiation with UVA (320-400nm). It is usually the dermatologist who decides which modality of PUVA is used (i.e. bath PUVA or systemic PUVA). Dermatologist's preferences for treating psoriasis have been studied, but not in relation to mode of PUVA therapy(1) . Furthermore, patient preferences for mode of PUVA delivery have also not been addressed in previous research. This study was conducted in order to explore patient preferences regarding mode of PUVA treatment. This article is protected by copyright. All rights reserved. PMID:25420468

Alshiyab, D; Chin, M F; Edwards, C; Anstey, A V

2014-11-24

10

Acral PUVA--induced pigmented macules.  

PubMed

This report describes four patients with chronic psoriasiform dermatitis of the palms and soles who developed pigmented macular lesions after localized photochemotherapy (PUVA) to these areas. These lesions had varied histopathologic presentations including lentigines, atypical melanocytic proliferation and a junction nevus suggesting a wide clinico pathologic spectrum in the PUVA-induced pigmented macules. PMID:2080960

Cruz, A; Sánchez, J L

1990-10-01

11

Neutrophil degranulation inhibits potential hydroxyl-radical formation. Relative impact of myeloperoxidase and lactoferrin release on hydroxyl-radical production by iron-supplemented neutrophils assessed by spin-trapping techniques.  

PubMed Central

Hydroxyl radical (.OH) formation by neutrophils in vitro requires exogenous iron. Two recent studies [Britigan, Rosen, Thompson, Chai & Cohen (1986) J. Biol. Chem. 261, 17026-17032; Winterbourn (1987) J. Clin. Invest. 78, 545-550] both reported that neutrophil degranulation could potentially inhibit the formation of .OH, but differed in their conclusions as to the responsible factor, myeloperoxidase (MPO) or lactoferrin (LF). By using a previously developed spin-trapping system which allows specific on-line detection of superoxide anion (O2-) and .OH production, the impact of MPO and LF release on neutrophil .OH production was compared. When iron-diethylenetriaminepenta-acetic acid-supplemented neutrophils were stimulated with phorbol myristate acetate or opsonized zymosan, .OH formation occurred, but terminated prematurely in spite of continued O2- generation. Inhibition of MPO by azide increased the magnitude, but not the duration, of .OH formation. No azide effect was noted when MPO-deficient neutrophils were used. Anti-LF antibody increased both the magnitude and duration of .OH generation. Pretreatment of neutrophils with cytochalasin B to prevent phagosome formation did not alter the relative impact of azide or anti-LF on neutrophil .OH production. An effect of azide or anti-LF on spin-trapped-adduct stability was eliminated as a confounding factor. These data indicate that neutrophils possess two mechanisms for limiting .OH production. Implications for neutrophil-derived oxidant damage are discussed. PMID:2557840

Britigan, B E; Hassett, D J; Rosen, G M; Hamill, D R; Cohen, M S

1989-01-01

12

Mechanisms of Degranulation in Neutrophils  

PubMed Central

Neutrophils are critical inflammatory cells that cause tissue damage in a range of diseases and disorders. Being bone marrow-derived white blood cells, they migrate from the bloodstream to sites of tissue inflammation in response to chemotactic signals and induce inflammation by undergoing receptor-mediated respiratory burst and degranulation. Degranulation from neutrophils has been implicated as a major causative factor in pulmonary disorders, including severe asphyxic episodes of asthma. However, the mechanisms that control neutrophil degranulation are not well understood. Recent observations indicate that granule release from neutrophils depends on activation of intracellular signalling pathways, including ?-arrestins, the Rho guanosine triphosphatase Rac2, soluble NSF attachment protein (SNAP) receptors, the src family of tyrosine kinases, and the tyrosine phosphatase MEG2. Some of these observations suggest that degranulation from neutrophils is selective and depends on nonredundant signalling pathways. This review focuses on new findings from the literature on the mechanisms that control the release of granule-derived mediators from neutrophils. PMID:20525154

2006-01-01

13

Photochemotherapy (PUVA) in psoriasis and vitiligo.  

PubMed

Phototherapy with photochemotherapy (PUVA) is a well-known and well-studied modality for the treatment of psoriasis, which involves systemic or topical administration of chemicals known as psoralens and administration of ultraviolet light in increasing dosages after requisite time gap. PUVA is also used in the treatment of widespread vitiligo with moderately good results, though it is being surpassed by ultraviolet B (UVB), which is equally or slightly more efficacious with fewer side effects. PUVA induces repigmentation by varying mechanisms such as stimulation of melanogenesis, immunomodulation and activation of growth factors, though the exact mechanism is still speculative. There are various studies evaluating the efficacy of PUVA in psoriasis as well as in vitiligo, either alone or in combination with other immunosuppressants like azathioprine and calcipotriene. PMID:25382505

Shenoi, Shrutakirthi D; Prabhu, Smitha

2014-01-01

14

Lipid Nanosystems in Topical PUVA Therapy  

Microsoft Academic Search

8-methoxsalen was vehicled in nanoemulsion and in solid lipid nanoparticles (SLN) prepared by hot homogenisation technique, in order to be used in the topical psoralen UVA (PUVA) therapy. Drug entrapment efficiency in nanoparticles was improved by choosing the appropriate lipid matrix. The use of ?-tocopherol in the lipid phase reduces 8-methoxsalen induced photo-oxidation of porcine skin, which was evaluated in

Luigi Battaglia; Elena Peira; Simona Sapino; Marina Gallarate

2011-01-01

15

Effects of PUVA on the eye  

SciTech Connect

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.

Backman, H.A.

1982-01-01

16

Mast cell degranulation breaks peripheral tolerance  

PubMed Central

Mast cells (MC) have been shown to mediate regulatory T-cell (Treg) dependent, peripheral allograft tolerance in both skin and cardiac transplants. Furthermore, Treg have been implicated in mitigating IgE mediated MC degranulation, establishing a dynamic, reciprocal relationship between MC and Treg in controlling inflammation. In an allograft tolerance model, it is now shown that intragraft or systemic MC degranulation results in the transient loss of Treg suppressor activities with the acute, T-cell dependent rejection of established, tolerant allografts. Upon degranulation, MC mediators can be found in the skin, Treg rapidly leave the graft, MC accumulate in the regional lymph node and the Treg are impaired in the expression of suppressor molecules. Such a dramatic reversal of Treg function and tissue distribution by MC degranulation underscores how allergy may causes the transient breakdown of peripheral tolerance and episodes of acute T-cell inflammation. PMID:19681828

de Vries, Victor C.; Wasiuk, Anna; Bennett, Kathryn A.; Benson, Micah J.; Elgueta, Raul; Waldschmidt, Thomas J.; Noelle, Randolph. J.

2013-01-01

17

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

PubMed Central

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-?-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

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

2013-01-01

18

Mast cell degranulation induced by chlorogenic acid  

PubMed Central

Aim: To investigate the mechanism of chlorogenic acid (CA)-induced anaphylactoid reactions. Methods: Degranulation of peritoneal mast cells was assayed by using alcian blue staining in guinea pigs, and the degranulation index (DI) was calculated. CA-induced degranulation of RBL-2H3 cells was also observed and assayed using light microscopy, transmission electron microscopy, flow cytometry, and ?-hexosaminidase release. Results: CA 0.2, 1.0, and 5.0 mmol/L was able to promote degranulation of peritoneal mast cells in guinea pigs in vitro, but it did not increase the degranulation of peritoneal mast cells in CA-sensitized guinea pigs compared with control (P>0.05). Treatment with CA 0.2, 1.0, and 5.0 mmol/L for 30, 60, and 120 min induced degranulation in RBL-2H3 cells in a dose- and time-dependent manner (P<0.01). Under transmission electron microscope typical characteristics of degranulation, including migration of granular vesicles toward the plasma membrane and integration combined with exocytosis, were observed, after CA or C48/80 treatment. Fluorescent microscopy and flow cytometric analysis showed that CA induced concentration-dependent translocation of phosphatidylserine in RBL-2H3 cells. ?-hexosaminidase release in RBL-2H3 cells was significantly increased after incubation with 1 mmol/L CA for 60 min and 5 mmol/L CA for 30 min (P<0.01). Conclusion: CA induces degranulation of peritoneal mast cells and RBL-2H3 cells in guinea pigs, which might be one of the mechanisms of the generation of anaphylactoid reactions induced by CA. PMID:20581858

Huang, Fang-hua; Zhang, Xin-yue; Zhang, Lu-yong; Li, Qin; Ni, Bin; Zheng, Xiao-liang; Chen, Ai-jun

2010-01-01

19

Treatment of stable vitiligo with autologous epidermal grafting and PUVA  

Microsoft Academic Search

Background: Previous reports have shown the benefits of epidermal grafting for vitiligo.Objective: Our purpose was to evaluate the effectiveness and complications of epidermal grafting in combination with PUVA on stable vitiligo refractory to conventional treatments.Methods: In 100 patients with stable refractory vitiligo we performed epidermal grafting with suction blisters followed by PUVA treatment. The grafted sites were examined for repigmentation

Seung Kyung Hann; Sungbin Im; Ha Wook Bong; Yoon-Kee Park

1995-01-01

20

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

SciTech Connect

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.

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

1981-06-01

21

Mathematical model of laser PUVA psoriasis treatment  

NASA Astrophysics Data System (ADS)

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.

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

1991-05-01

22

Effect of methylmercury on the rat mast cell degranulation  

NASA Astrophysics Data System (ADS)

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.

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

2003-05-01

23

Microvascular leakage of plasma proteins after PUVA and UVA  

SciTech Connect

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.

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

1982-04-01

24

Dual regulation of mast cell degranulation through IgE receptor-mediated modulation of M2-type pyruvate kinase.  

PubMed

It was reported that mast cell degranulation is inversely related to the enzymatic activity of M2-type pyruvate kinase (M2PK). This study shows that activation of high-affinity IgE receptor (Fc?RI) evokes a sequential dual regulation of M2PK, i.e., an immediate decrement followed by slow phase increment of enzymatic activities. Changes in the activities of M2PK and mast cell degranulation showed similar time course after antigenic stimulation of Fc?RI. The immediate inhibition of M2PK involved tyrosine phosphorylation, and subsequently led to a cellular accumulation of glycolytic intermediates, including fructose 1,6-biphosphate (FBP), a feedforward activator of M2PK. As the cellular levels of FBP were increased, both the enzymatic acitivity of M2PK and mast cell degranulation slowly returned to near basal levels. A-Raf, when exogenously introduced into RBL-2H3 cells, phosphorylated M2PK on the serine residues, elevated enzyme activities of M2PK, and resulted in the inhibition of degranulation. These results suggest that dual regulation of M2PK which involves the phosphorylation of M2PK and accumulation of a feedforward activator of M2PK plays important roles in the control of mast cell degranulation. PMID:24497038

Zheng, Mei; Cho, Dong-Im; Le, Hang Thi; Cheon, Seung Hoon; Kim, Kyeong-Man

2014-09-01

25

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

PubMed Central

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

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

2014-01-01

26

Negative Regulation of Fc?RI-mediated Degranulation by CD81  

PubMed Central

Signaling through the high affinity receptor for immunoglobulin E (Fc?RI) results in the coordinate activation of tyrosine kinases before calcium mobilization. Receptors capable of interfering with the signaling of antigen receptors, such as Fc?RI, recruit tyrosine and inositol phosphatases that results in diminished calcium mobilization. Here, we show that antibodies recognizing CD81 inhibit Fc?RI-mediated mast cell degranulation but, surprisingly, without affecting aggregation-dependent tyrosine phosphorylation, calcium mobilization, or leukotriene synthesis. Furthermore, CD81 antibodies also inhibit mast cell degranulation in vivo as measured by reduced passive cutaneous anaphylaxis responses. These results reveal an unsuspected calcium-independent pathway of antigen receptor regulation, which is accessible to engagement by membrane proteins and on which novel therapeutic approaches to allergic diseases could be based. PMID:9334370

Fleming, Tony J.; Donnadieu, Emmanuel; Song, Chang Ho; Laethem, Francois Van; Galli, Stephen J.; Kinet, Jean-Pierre

1997-01-01

27

Further studies on rat mast cell degranulation by IgE—anti-IgE and the inhibitory effect of drugs related to cAMP  

PubMed Central

With a modified rat mast cell degranulation (RMCD) technique developed by Korotzer, Haddad and Lopapa (1971), the mechanism of mast cell degranulation by IgE—anti-IgE reaction and the inhibitory effect of cAMP-related compounds upon IgE-mediated mast cell degranulation were studied. Degranulations of 90 per cent or more were decreased to 13–16 per cent when the mast cells were pretreated with human IgE or normal human serum. However, if rat mast cells were pretreated with anti-human IgE rabbit serum or normal rabbit serum, the degranulation per cent in these cells by IgE—anti-IgE reaction was the same as in the nontreated cells. These results suggest the presence of receptors in rat mast cells for human IgE or normal human serum, and the lack of receptors in these cells for anti-human IgE rabbit serum or normal rabbit serum. Treatment of isolated rat mast cells with adenyl cyclase stimulating agents (isoprenaline, adrenaline, prostaglandin E1 and E2) and theophylline or aminophylline, which inhibit the enzymatic degradation of cAMP, also inhibited the morphological degranulation of the mast cells. Cromoglycate or chlorophenes in derivatives, which might have a stabilizing effect of the cell membrane, also inhibited the degranulation of the rat mast cells mediated by IgE—anti-IgE reaction. These results support the attractive hypothesis that cAMP occupies a central modulatory role in the in vitro mast cell degranulation by IgE—anti-IgE reaction. PMID:4368738

Kimura, Y.; Inoue, Yoshie; Honda, H.

1974-01-01

28

Antiangiogenic effect of methotrexate and PUVA on psoriasis.  

PubMed

Vascular endothelial growth factor (VEGF) is important factor for angiogenesis in psoriasis. Methotrexate and psoralen and ultraviolet light A (PUVA) mainly target the T cell-mediated immunopathology of psoriasis. Our work aimed at estimating VEGF mRNA in psoriatic patients and investigating whether the standard therapeutic modalities (methotrexate and PUVA) exert their antiangiogenic activity through altering VEGF levels. Twenty-four chronic plaque psoriasis patients were enrolled. Patients were divided into two groups (12 patients each); group A received intramuscular methotrexate and group B was treated by PUVA three times/week in a PUVA 1000 cabin for 10 weeks each. Twelve healthy volunteers served as controls. A skin biopsy was taken from lesional skin before and after treatment for RT-PCR detection of VEGF mRNA. Capillary perfusion scanning using LASER Doppler perfusion imaging was performed on the same psoriatic plaque before and after treatment and was also done for the controls. Following both methotrexate and PUVA, a significant reduction in the amount of VEGF mRNA (P < 0.001 and P = 0.002, respectively) and capillary perfusion (P = 0.002) occurred. These reductions were significantly higher in the methotrexate group (P < 0.001 and  P = 0.001, respectively) than in the PUVA group. The percentage of clinical improvement in the examined psoriatic plaque was significantly positively correlated with the percentage of reduction in the amount of VEGF mRNA (r = 0.850, P < 0.001) and the percentage of reduction in the capillary perfusion (r = 0.684, P < 0.001). Both modalities may exert an antiangiogenic effect. Methotrexate appears to have possibly a more potent antiangiogenic effect than PUVA. PMID:23504632

Shaker, Olfat G; Khairallah, Mongy; Rasheed, Hoda M; Abdel-Halim, Mona R; Abuzeid, Ola M; El Tawdi, Amira M; El Hadidi, Heba H; Ashmaui, Ali

2013-11-01

29

JNK1 controls mast cell degranulation and IL-1? production in inflammatory arthritis  

PubMed Central

Rheumatoid arthritis (RA) is a chronic inflammatory disease marked by bone and cartilage destruction. Current biologic therapies are beneficial in only a portion of patients; hence small molecules targeting key pathogenic signaling cascades represent alternative therapeutic strategies. Here we show that c-Jun N-terminal kinase (JNK) 1, but not JNK2, is critical for joint swelling and destruction in a serum transfer model of arthritis. The proinflammatory function of JNK1 requires bone marrow-derived cells, particularly mast cells. Without JNK1, mast cells fail to degranulate efficiently and release less IL-1? after stimulation via Fc? receptors (Fc?Rs). Pharmacologic JNK inhibition effectively prevents arthritis onset and abrogates joint swelling in established disease. Hence, JNK1 controls mast cell degranulation and Fc?R-triggered IL-1? production, in addition to regulating cytokine and matrix metalloproteinase biosynthesis, and is an attractive therapeutic target in inflammatory arthritis. PMID:21135226

Guma, Monica; Kashiwakura, Jun-ichi; Crain, Brian; Kawakami, Yuko; Beutler, Bruce; Firestein, Gary S.; Kawakami, Toshiaki; Karin, Michael; Corr, Maripat

2010-01-01

30

JNK1 controls mast cell degranulation and IL-1{beta} production in inflammatory arthritis.  

PubMed

Rheumatoid arthritis (RA) is a chronic inflammatory disease marked by bone and cartilage destruction. Current biologic therapies are beneficial in only a portion of patients; hence small molecules targeting key pathogenic signaling cascades represent alternative therapeutic strategies. Here we show that c-Jun N-terminal kinase (JNK) 1, but not JNK2, is critical for joint swelling and destruction in a serum transfer model of arthritis. The proinflammatory function of JNK1 requires bone marrow-derived cells, particularly mast cells. Without JNK1, mast cells fail to degranulate efficiently and release less IL-1? after stimulation via Fc? receptors (Fc?Rs). Pharmacologic JNK inhibition effectively prevents arthritis onset and abrogates joint swelling in established disease. Hence, JNK1 controls mast cell degranulation and Fc?R-triggered IL-1? production, in addition to regulating cytokine and matrix metalloproteinase biosynthesis, and is an attractive therapeutic target in inflammatory arthritis. PMID:21135226

Guma, Monica; Kashiwakura, Jun-ichi; Crain, Brian; Kawakami, Yuko; Beutler, Bruce; Firestein, Gary S; Kawakami, Toshiaki; Karin, Michael; Corr, Maripat

2010-12-21

31

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

SciTech Connect

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.

Descalle, M.A.; Laing, T.J.; Martin, W.R. [Univ. of Michigan, Ann Arbor, MI (United States)

1996-12-31

32

Stimulus-Selective Regulation of Human Mast Cell Gene Expression, Degranulation and Leukotriene Production by Fluticasone and Salmeterol  

PubMed Central

Despite the fact that glucocorticoids and long acting beta agonists are effective treatments for asthma, their effects on human mast cells (MC) appear to be modest. Although MC are one of the major effector cells in the underlying inflammatory reactions associated with asthma, their regulation by these drugs is not yet fully understood and, in some cases, controversial. Using a human immortalized MC line (LAD2), we studied the effects of fluticasone propionate (FP) and salmeterol (SM), on the release of early and late phase mediators. LAD2 cells were pretreated with FP (100 nM), SM (1 µM), alone and in combination, at various incubation times and subsequently stimulated with agonists substance P, C3a and IgE/anti-IgE. Degranulation was measured by the release of ?-hexosaminidase. Cytokine and chemokine expression were measured using quantitative PCR, ELISA and cytometric bead array (CBA) assays. The combination of FP and SM synergistically inhibited degranulation of MC stimulated with substance P (33% inhibition compared to control, n?=?3, P<.05). Degranulation was inhibited by FP alone, but not SM, when MC were stimulated with C3a (48% inhibition, n?=?3, P<.05). As previously reported, FP and SM did not inhibit degranulation when MC were stimulated with IgE/anti-IgE. FP and SM in combination inhibited substance P-induced release of tumor necrosis factor (TNF), CCL2, and CXCL8 (98%, 99% and 92% inhibition, respectively, n?=?4, P<.05). Fluticasone and salmeterol synergistically inhibited mediator production by human MC stimulated with the neuropeptide substance P. This synergistic effect on mast cell signaling may be relevant to the therapeutic benefit of combination therapy in asthma. PMID:24819142

Catalli, Adriana; Karpov, Victor; Erdos, Levente E.; Tancowny, Brian P.; Schleimer, Robert P.; Kulka, Marianna

2014-01-01

33

Stimulus-selective regulation of human mast cell gene expression, degranulation and leukotriene production by fluticasone and salmeterol.  

PubMed

Despite the fact that glucocorticoids and long acting beta agonists are effective treatments for asthma, their effects on human mast cells (MC) appear to be modest. Although MC are one of the major effector cells in the underlying inflammatory reactions associated with asthma, their regulation by these drugs is not yet fully understood and, in some cases, controversial. Using a human immortalized MC line (LAD2), we studied the effects of fluticasone propionate (FP) and salmeterol (SM), on the release of early and late phase mediators. LAD2 cells were pretreated with FP (100 nM), SM (1 µM), alone and in combination, at various incubation times and subsequently stimulated with agonists substance P, C3a and IgE/anti-IgE. Degranulation was measured by the release of ?-hexosaminidase. Cytokine and chemokine expression were measured using quantitative PCR, ELISA and cytometric bead array (CBA) assays. The combination of FP and SM synergistically inhibited degranulation of MC stimulated with substance P (33% inhibition compared to control, n?=?3, P<.05). Degranulation was inhibited by FP alone, but not SM, when MC were stimulated with C3a (48% inhibition, n?=?3, P<.05). As previously reported, FP and SM did not inhibit degranulation when MC were stimulated with IgE/anti-IgE. FP and SM in combination inhibited substance P-induced release of tumor necrosis factor (TNF), CCL2, and CXCL8 (98%, 99% and 92% inhibition, respectively, n?=?4, P<.05). Fluticasone and salmeterol synergistically inhibited mediator production by human MC stimulated with the neuropeptide substance P. This synergistic effect on mast cell signaling may be relevant to the therapeutic benefit of combination therapy in asthma. PMID:24819142

Catalli, Adriana; Karpov, Victor; Erdos, Levente E; Tancowny, Brian P; Schleimer, Robert P; Kulka, Marianna

2014-01-01

34

Mathematical modeling for laser PUVA treatment of psoriasis  

NASA Astrophysics Data System (ADS)

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.

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

1991-06-01

35

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

SciTech Connect

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.

Sanchez-Miranda, Elizabeth; Ibarra-Sanchez, Alfredo [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico)] [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico); Gonzalez-Espinosa, Claudia, E-mail: cgonzal@cinvestav.mx [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico)] [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados (Cinvestav), Sede Sur, Calzada de los Tenorios 235, Col. Granjas Coapa, CP 14330 Mexico City (Mexico)

2010-01-22

36

PUVA-induced lymphocyte apoptosis: mechanism of action in psoriasis.  

PubMed

Psoralen plus ultraviolet A (PUVA), utilizing oral 8-methoxypsoralen (8-MOP), is a widely utilized and effective treatment for psoriasis vulgaris. Previous studies have suggested that PUVA's mechanism of action in psoriasis is a result of its direct lymphotoxic effects. Trimethylpsoralen (TMP), a potentially safer compound, has been found to be effective in psoriasis during bath water delivery. In this study we examined the relative antilymphocytic effects of TMP and 8-MOP through both flow cytometry and tissue analysis on lesional skin during clinical treatment. Based on FACS analysis on phytohemagglutinin-activated lymphocytes, we found TMP to be nearly 10,000 fold more lymphotoxic compared to 8-MOP. In addition, lymphocytes treated with 8-MOP or TMP with UVA displayed DNA degradation patterns typical of apoptotic cell death. These findings were consistent with our investigation of treated psoriatic skin, with virtual elimination of epidermal CD3+ T-cells following bath water treatment with TMP or 8-MOP. These results support the theory that the therapeutic effects of PUVA stem from its toxic effects on activated lymphocytes. If further investigation supports TMP's lack of carcinogenicity, this potent lymphotoxic treatment may prove to be one of the safest and most effective treatments for psoriasis. PMID:9990665

Coven, T R; Walters, I B; Cardinale, I; Krueger, J G

1999-02-01

37

Silver nanoparticle-induced degranulation observed with quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

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 ?g/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.

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

2010-07-01

38

Class I PI3K-mediated Akt and ERK signals play a critical role in Fc?RI-induced degranulation in mast cells.  

PubMed

Class IA and IB phosphoinositide 3-kinases (PI3Ks) have been shown to regulate mast cell functions such as proliferation, development, survival and degranulation, but the functional redundancy between these two PI3K signaling pathways in mast cells remains unclear. Here, we have generated mice deficient in both class IA regulatory subunit p85? and class IB catalytic subunit p110?, and show that p85?(-/-)p110?(-/-) mice exhibit a more severe defect in mast cell development than single-knockout mice. In addition, the in vivo passive cutaneous anaphylaxis reaction of p85?(-/-)p110?(-/-) mice was nearly completely abrogated, whereas single-knockout mice exhibit just marginal reduction. Pharmacological inactivation of Akt in wild-type bone marrow-derived mast cells (BMMCs) led to partial reduction of degranulation, while over-expression of a constitutively active Akt partially restored the impaired degranulation in p85?(-/-)p110?(-/-) BMMCs. We also found that the extracellular signal-regulated kinase (ERK) signaling pathway was activated in a PI3K-dependent manner upon Fc?RI stimulation and that simultaneous inhibition of Akt and ERK resulted in nearly complete blockade of Fc?RI-induced degranulation. Our data provide evidence that Akt and ERK pathways play redundant roles in Fc?RI-induced degranulation. PMID:23143475

Takayama, Gensuke; Ohtani, Masashi; Minowa, Akiko; Matsuda, Satoshi; Koyasu, Shigeo

2013-04-01

39

Galectin-9 Enhances Cytokine Secretion, but Suppresses Survival and Degranulation, in Human Mast Cell Line  

PubMed Central

Galectin-9 (Gal-9), a lectin having a ?-galactoside-binding domain, can induce apoptosis of Th1 cells by binding to TIM-3. In addition, Gal-9 inhibits IgE/Ag-mediated degranulation of mast cell/basophilic cell lines by binding to IgE, thus blocking IgE/Ag complex formation. However, the role of Gal-9 in mast cell function in the absence of IgE is not fully understood. Here, we found that recombinant Gal-9 directly induced phosphorylation of Erk1/2 but not p38 MAPK in a human mast cell line, HMC-1, which does not express Fc?RI. Gal-9 induced apoptosis and inhibited PMA/ionomycin-mediated degranulation of HMC-1 cells. On the other hand, Gal-9 induced cytokine and/or chemokine production by HMC-1 cells, dependent on activation of ERK1/2 but not p38 MAPK. In addition, the lectin activity of Gal-9 was required for Gal-9-mediated cytokine secretion by HMC-1 cells. These observations suggest that Gal-9 has dual properties as both a regulator and an activator of mast cells. PMID:24465902

Iikura, Motoyasu; Niki, Toshiro; Hirashima, Mitsuomi; Iwaya, Keichi; Tsuda, Hitoshi; Nonoyama, Shigeaki; Matsuda, Akio; Saito, Hirohisa; Matsumoto, Kenji; Nakae, Susumu

2014-01-01

40

Acrolein induction of oxidative stress and degranulation in mast cells.  

PubMed

Increases in asthma worldwide have been associated epidemiologically with expanding urban air pollution. The mechanistic relationship between airway hyper-responsiveness, inflammation, and ambient airborne triggers remains ambiguous. Acrolein, a ubiquitous aldehyde pollutant, is a product of incomplete combustion reactions. Acrolein is abundant in cigarette smoke, effluent from industrial smokestacks, diesel exhaust, and even hot oil cooking vapors. Acrolein is a potent airway irritant and can induce airway hyper-responsiveness and inflammation in the lungs of animal models. In the present study, we utilized the mast cell analog, RBL-2H3, to interrogate the responses of cells relevant to airway inflammation and allergic responses as a model for the induction of asthma-like conditions upon exposure to acrolein. We hypothesized that acrolein would induce oxidative stress and degranulation in airway mast cells. Our results indicate that acrolein at 1 ppm initiated degranulation and promoted the generation of reactive oxygen species (ROS). Introduction of antioxidants to the system significantly reduced both ROS generation and degranulation. At higher levels of exposure (above 100 ppm), RBL-2H3 cells displayed signs of severe toxicity. This experimental data indicates acrolein can induce an allergic inflammation in mast cell lines, and the initiation of degranulation was moderated by the application of antioxidants. PMID:23047665

Hochman, Daniel J; Collaco, Christopher R; Brooks, Edward G

2014-08-01

41

[Granulomatous mycosis fungoides: combination therapy with bexarotene and PUVA].  

PubMed

A 74-year-old male with granulomatous mycosis fungoides presented with multiple, red-brown macules and plaques up to 8 cm in diameter, just as in classical mycosis fungoides. Dermatohistopathologic findings showed extensive granulomatous infiltrates, in which clonality could be detected in various locations via T cell receptor rearrangement. Granulomatous mycosis fungoides is a very rare form of mycosis fungoides with histological resemblance to granulomatous slack skin. It shows a rather aggressive course and can be challenging to diagnose. In our case, combination treatment with bexarotene and bath PUVA, as recommended in guidelines, resulted in an impressive improvement of the skin lesions within ten weeks. PMID:24671704

Wirtz, M; Helbig, D

2014-04-01

42

hsa-miR-4516 mediated downregulation of STAT3/CDK6/UBE2N plays a role in PUVA induced apoptosis in keratinocytes.  

PubMed

Psoriasis is a chronic inflammatory skin disorder mediated by cross-talk occurring between epidermal keratinocytes, dermal vascular cells and immunocytes. Literature reveals that Signal transducer and activator of transcription 3 (STAT3), a protein involved in transmitting extracellular signals to the nucleus, is a possible important link between keratinocytes and immunocytes and is crucial to the development of psoriasis. Although photochemotherapy using UV in combination with 8 methoxypsoralen is one of the most effective therapy for moderate to severe plaque psoriasis, its mechanism of action is largely unknown. Herein, we studied the change in miRNA profiles of cultured human keratinocytes (HaCaT cells) before and after in vitro PUVA treatment by 8 methoxypsoralen and found significant up regulation of hsa-miR-4516. We for the first time demonstrate that ectopic expression of hsa-miR-4516 directly targets STAT3 protein by binding to its 3'UTR in HaCaT cells as confirmed by Luciferase reporter assays and Western blot analysis. We further show that overexpression of hsa-miR-4516 downregulates STAT3, p-STAT3, CDK6, and UBE2N proteins that are consistently upregulated in psoriasis and induces apoptosis in HaCaT cells. We also observed that anti-miR-4516 treatment was able to partially inhibit PUVA-induced apoptosis, suggesting that miR-4516 is involved in PUVA-induced apoptosis. Taken together, these results not only indicate the mechanistic involvement of hsa-miR-4516 in PUVA mediated effects by down-regulating STAT3 in HaCaT keratinocytes, but also highlight the potential of hsa-miR-4516 in development of novel therapeutic strategies. J. Cell. Physiol. 229: 1630-1638, 2014. © 2014 Wiley Periodicals, Inc. PMID:24610393

Chowdhari, Shruti; Saini, Neeru

2014-11-01

43

An Acidic Microenvironment Increases NK Cell Killing of Cryptococcus neoformans and Cryptococcus gattii by Enhancing Perforin Degranulation  

PubMed Central

Cryptococcus gattii and Cryptococcus neoformans are encapsulated yeasts that can produce a solid tumor-like mass or cryptococcoma. Analogous to malignant tumors, the microenvironment deep within a cryptococcoma is acidic, which presents unique challenges to host defense. Analogous to malignant cells, NK cells kill Cryptococcus. Thus, as in tumor defense, NK cells must kill yeast cells across a gradient from physiologic pH to less than 6 in the center of the cryptococcoma. As acidic pH inhibits anti-tumor activities of NK cells, we sought to determine if there was a similar reduction in the anticryptococcal activity of NK cells. Surprisingly, we found that both primary human NK cells and the human NK cell line, YT, have preserved or even enhanced killing of Cryptococcus in acidic, compared to physiological, pH. Studies to explore the mechanism of enhanced killing revealed that acidic pH does not increase the effector to target ratio, binding of cytolytic cells to Cryptococcus, or the active perforin content in effector cells. By contrast, perforin degranulation was greater at acidic pH, and increased degranulation was preceded by enhanced ERK1/2 phosphorylation, which is essential for killing. Moreover, using a replication defective ras1 knockout strain of Cryptococcus increased degranulation occurred during more rapid replication of the organisms. Finally, NK cells were found intimately associated with C. gattii within the cryptococcoma of a fatal infection. These results suggest that NK cells have amplified signaling, degranulation, and greater killing at low pH and when the organisms are replicating quickly, which would help maintain microbicidal host defense despite an acidic microenvironment. PMID:23853583

Islam, Anowara; Li, Shu Shun; Oykhman, Paul; Timm-McCann, Martina; Huston, Shaunna M.; Stack, Danuta; Xiang, Richard F.; Kelly, Margaret M.; Mody, Christopher H.

2013-01-01

44

The tetraspanin CD63 is required for efficient IgE-mediated mast cell degranulation and anaphylaxis1  

PubMed Central

Mast cell activation through the high affinity IgE receptor Fc?RI leads to the release of mediators involved in immediate-type allergic reactions. While antibodies against the tetraspanins CD63 and CD81 inhibit Fc?RI-induced mast cell degranulation, the intrinsic role of these molecules in Fc?RI-induced mast cell activation is unknown. In mast cells, CD63 is expressed at the cell surface and in lysosomes (particularly secretory lysosomes that contain allergic mediators). Here, we investigated the role of CD63 in mast cells using a CD63 knockout mouse model. CD63-deficiency did not affect in vivo mast cell numbers and tissue distribution. Bone-marrow-derived mast cells (BMMC) developed normally in the absence of CD63 protein. However, CD63-deficient BMMC showed a significant decrease in Fc?RI-mediated degranulation, but not PMA/ionomycin-induced degranulation, as shown by ?-hexosaminidase release assays. The secretion of TNF-?, which is both released from granules and synthesized de novo upon mast cell activation, was also decreased. IL-6 secretion, and production of the lipid mediator leukotriene C4 were unaffected. There were no ultrastructural differences in granule content and morphology, late endosomal/lysosomal marker expression, Fc?RI-induced global tyrosine phosphorylation, and Akt phosphorylation. Finally, local reconstitution in genetically mast cell-deficient Kitw/w-v mice was unaffected by the absence of CD63. However, the sites reconstituted with CD63-deficient mast cells developed significantly attenuated cutaneous anaphylactic reactions. These findings demonstrate that the absence of CD63 results in a significant decrease of mast cell degranulation, which translates into a reduction of acute allergic reactions in vivo, thus identifying CD63 as an important component of allergic inflammation. PMID:23945142

Kraft, Stefan; Jouvin, Marie-Hélène; Kulkarni, Nitin; Kissing, Sandra; Morgan, Ellen S.; Dvorak, Ann M.; Schröder, Bernd; Saftig, Paul; Kinet, Jean-Pierre

2013-01-01

45

Silver nanoparticle-induced degranulation observed with quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

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, 50?g/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.

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

2010-02-01

46

PUVA Induced Bullous Pemphigoid in a Patient with Psoriasis.  

PubMed

A bullous eruption in a patient with psoriasis was first described by Bloom in 1929 (as cited by Weber) (1). Since then there have been several reports of bullous pemphigoid occurring during the treatment of psoriasis, especially after ultraviolet (UV) B exposure. Comorbidity of these two diseases without treatment has also been reported (2,3). Psoriasis is one of the most common chronic inflammatory skin diseases. Its etiopathogenesis is unknown, but nonspecific inflammatory processes and specific immunologic factors have been described. Autoimmune processes occurring within the epidermis and immunologic responses to exogenous infectious agents are suspected as causes, but not confirmed. In contrast, bullous pemphigoid (BP) represents a distinct autoimmune disease in which basement membrane zone (BMZ) molecules are most affected (4). BP is an autoimmune subepidermal bullous disease with circulating autoantibodies against BP antigen 1 (230kDa) and BP antigen 2 (180kDa). Antigen 2 is a transmembrane glycoprotein located in the hemidesmosomes and is the major antigenic target in this disorder (5,6). The BP180 NC16a domain is considered to be the most immunogenic site (7). The occurrence of BP in patients with psoriasis has occasionally been reported (8). Although the pathogenetic mechanism of comorbidity of psoriasis vulgaris and BP is unclear, a common immunogenetic mechanism might be involved (9). Most previously reported cases attributed the occurrence of BP in psoriasis to photochemotherapy and phototherapy (PUVA, UVA, UVB311nm), topical treatment with anthralin, tar, and as a result of systemic application of anti-TNF antibodies (10). The role of PUVA therapy in the development of BP remains unknown. George at al. suggested that such changes may trigger the development of antibodies which may later cross-react with proteins, such as the BP antigen, causing a bullous eruption to appear. The possibility that PUVA induces the alteration of immunologic reactivity of T-helper and T-suppressor cells, allowing the development of autoantibodies against native proteins, has also been raised (6,11). A 55-year-old woman was referred to our department with a ten days history of bullous lesions, erosions, and exacerbated plaque psoriasis. Psoriasis was diagnosed in 1994, and various systemic and topical therapies (in combination or as single treatment) were prescribed, such as topical corticosteroids, cyclosporine, and methotrexate. Three courses of PUVA therapy (cumulative dose 291 J/cm²) had been given several days before hospitalization. On examination, extensive psoriatic plaques, vesicles and tense blisters up to 3 cm in diameter, filled with clear fluid, located on both the normal skin and psoriatic lesions were observed all over the body. The highest intensity of bullous skin lesions was found in the upper limbs and lower limbs (Fig. 1 and 2). No lesions were observed on the face or on the mucous membranes. Routine laboratory tests such as biochemical tests, complete blood count, and urinalysis were normal. Chest radiography and abdominal ultrasonography, tumor markers CEA, and AFP showed no abnormalities. Two biopsy specimens were taken from psoriatic and bullous lesions for histopathologic examination, and one biopsy was taken from a perilesional bullous area located on the right forearm for a direct immunofluorescence test (DIF). Histopathologic examination revealed a subepidermal blister with eosinophils, fibrin, and neutrophils. Perivascular edema and lymphohistiocytic infiltration with eosinophils was observed in upper dermis (Fig. 3). DIF test showed linear C3c deposits at the dermal-epidermal junction (Fig. 4). C3c was present at both the epidermal and dermal sides of BMZ in salt-split skin examination (Fig. 5). Indirect immunofluorescence study (IIF) was done using monkey esophagus substrate and demonstrated IgG antibasement membrane zone antibodies (Fig. 6). Enzyme-linked immunosorbent assay (ELISA) confirmed high titers of anti-BP180 (>200 E/ml) and anti-BP230 (140 E/ml) with negative results for anti-envopla

Marek-Jozefowicz, Luiza; Scibior, Kinga; Czajkowski, Rafa?

2014-12-01

47

The inhibitory effect of piperine from Fructus piperis extract on the degranulation of RBL-2H3 cells.  

PubMed

Allergy is an abnormal immune response to an allergen. Type I hypersensitivity is an immunoglobulin (Ig) E-mediated allergic disorder. Fructus piperis is derived from the ripe fruit of the pepper, which is widely used as a spice in human diets and is also administered as a medicine in many countries. Piperine has been shown to have anti-oxidant, anti-depressant, anti-tumor, and anti-inflammatory activities. However, the effect of piperine on IgE-mediated allergic responses has not been reported. Here, the rat basophilic leukemia cells by membrane chromatography (RBL-2H3/CMC) coupled to high performance liquid chromatography/mass spectrometry (HPLC/MS) to discover and identify piperine can bind to RBL-2H3 cell membranes. Piperine inhibited the expression of cytokines, and the release of both ?-hexosaminidase and histamine, which could be stimulated by antigen in RBL-2H3 mast cells. We found that the levels of intracellular Ca(2+) also decreased. Furthermore, RT-PCR showed that the mRNA expression levels of IL-4, IL-13, and TNF-? were significantly suppressed by piperine. The inhibitory effect of piperine on IgE-mediated degranulation and cytokine production by RBL-2H3 cells may be caused by the inhibition of IgE-mediated signaling pathways, including the phosphorylation of Lyn, p38, Erk, and Ras. In summary, piperine can inhibit antigen-induced allergic reactions that control degranulation. PMID:25307563

Huang, Jing; Zhang, Tao; Han, Shengli; Cao, Jingjing; Chen, Qinhua; Wang, Sicen

2014-12-01

48

Mast cell activation and degranulation occur early during induction of periosteal bone resorption.  

PubMed

We have previously postulated that mast cells participate in the cellular network involved in osteoclastic resorption, probably through histamine release. In this study, we examined mast cell activation and histamine release during origination of resorption. Groups of 10 rats were killed 0, 0.5, 1, 1.5, 3, 6, 9, 12 and 18 h after induction of resorption in a synchronized model of cortical resorption along the mandible. The total number of mast cells was transiently decreased by about one-third at 1 and 9 h. Mast cell activation was monitored by Alcian blue-safranin staining. Early after induction, mast cells started to release their mediator stores; complete release led to the apparent disappearance of the cells with the staining technique used. Histamine immunostaining confirmed the release of histamine and its diffusion in the extracellular environment. Massive degranulation was observed at 1.5 and 9 h with toluidine blue staining. Cell recovery, assessed in terms of histidine decarboxylase expression, occurred gradually. The number of ED1+ osteoclast precursors strongly increased from 12 h up to 18 h. Most parameters had returned to baseline at 18 h, except the ED1+ cells. H2 receptor inhibition with famotidine strongly decreased ED1+ osteoclast precursors at 12 h and subsequently osteoclasts at the peak of resorption. These data support a role of mast cells in resorption origination. They show an early and transient intervention of mast cells in the events regulating the recruitment of circulating osteoclast precursors and ultimately of resorption. Mast cell activation and degranulation induce the release of mediators, particularly histamine acting through its H2 receptors, which are likely involved in these reactions. PMID:16249129

Fouilloux, I; Duplan, M Biosse; Baroukh, B; Cherruau, M; Saffar, J L; Lesclous, Ph

2006-01-01

49

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

PubMed Central

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

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

2005-01-01

50

Studies on the Specific Degranulation of Mast Cell Sensitized by Several Allergens in Vitro  

Microsoft Academic Search

Food allergy is a major health issue worldwide. Mast cells play a very important role in the immediate hypersensitivity for which mast cell degranulation needs to be studied extensively. In this study, an approach was taken to study the characteristics of sensitized mast cell degranulation in vitro, which associated with the study of mast cells and animal models. BALB\\/c mice

Yongchao Guo; Zhenxing Li; Hong Lin; Haider Samee; Jamil Khalid

2009-01-01

51

Molecular Mechanisms of N-Formyl-Methionyl-Leucyl-Phenylalanine-Induced Superoxide Generation and Degranulation in Mouse Neutrophils: Phospholipase D Is Dispensable  

PubMed Central

Phospholipase D (PLD), which produces the lipid messenger phosphatidic acid (PA), has been implicated in superoxide generation and degranulation in neutrophils. The basis for this conclusion is the observation that primary alcohols, which interfere with PLD-catalyzed PA production, inhibit these neutrophil functions. However, off-target effects of primary alcohols cannot be totally excluded. Here, we generated PLD?/? mice in order to reevaluate the involvement of PLD in and investigate the molecular mechanisms of these neutrophil functions. Surprisingly, N-formyl-methionyl-leucyl-phenylalanine (fMLP) induced these functions in PLD?/? neutrophils, and these functions were suppressed by ethanol. These results indicate that PLD is dispensable for these neutrophil functions and that ethanol nonspecifically inhibits them, warning against the use of primary alcohols as specific inhibitors of PLD-mediated PA formation. The calcium ionophore ionomycin and the membrane-permeative compound 1-oleoyl-2-acetyl-sn-glycerol (OADG) synergistically induced superoxide generation. On the other hand, ionomycin alone induced degranulation, which was further augmented by OADG. These results demonstrate that conventional protein kinase C (cPKC) is crucial for superoxide generation, and a Ca2+-dependent signaling pathway(s) and cPKC are involved in degranulation in mouse neutrophils. PMID:23109426

Sato, Takanobu; Hongu, Tsunaki; Sakamoto, Megumi; Funakoshi, Yuji

2013-01-01

52

Randomized controlled observer-blinded treatment of chronic foot eczema with iontophoresis and bath-PUVA.  

PubMed

The aim of this study was to investigate the effect of iontophoresis combined with local psoralen plus ultraviolet A (PUVA) therapy in chronic foot eczema. A randomized, observer-blinded, multi-centre study was conducted in 48 patients with chronic moderate-to-severe foot eczema randomized to one of 3 groups: In the iontophoresis group local bath-PUVA was preceded by iontophoresis. In the PUVA group only local PUVA was given. The corticosteroid group was treated with fluticasone. All treatments were given for 8 weeks, with an 8-week follow-up period. The primary efficacy parameter was eczema score described by Rosén et al. Secondary efficacy parameters were a global impression by the patient, and the Dermatology Life Quality Index (DLQI). The eczema score and the DLQI decreased significantly over time. There were no significant differences in the decrease in eczema score (p=0.053) and DLQI values (p=0.563) between the 3 treatments. The DLQI values in our chronic foot eczema patients were high. There was no obvious advantage of local bath-PUVA with or with-out iontophoresis over local steroid therapy. PMID:23420314

Tupker, Ron A; Coenraads, Pieter J; Zanen, Pieter; Schuttelaar, Marie Louise A

2013-07-01

53

Mast cell degranulation activates a pain pathway underlying migraine headache  

PubMed Central

Intracranial headaches such as that of migraine are generally accepted to be mediated by prolonged activation of meningeal nociceptors but the mechanisms responsible for such nociceptor activation are poorly understood. In this study, we examined the hypothesis that meningeal nociceptors can be activated locally through a neuroimmune interaction with resident mast cells, granulated immune cells that densely populate the dura mater. Using in vivo electrophysiological single unit recording of meningeal nociceptors in the rat we observed that degranulation of dural mast cells using intraperitoneal administration of the basic secretagogue agent compound 48/80 (2 mg/kg) induced a prolonged state of excitation in meningeal nociceptors. Such activation was accompanied by increased expression of the phosphorylated form of the extracellular signal-regulated kinase (pERK), an anatomical marker for nociceptor activation. Mast cell - induced nociceptor interaction was also associated with downstream activation of the spinal trigeminal nucleus as indicated by an increase in c-fos expression. Our findings provide evidence linking dural mast cell degranulation to prolonged activation of the trigeminal pain pathway believed to underlie intracranial headaches such as that of migraine. PMID:17459586

Levy, Dan; Burstein, Rami; Kainz, Vanessa; Jakubowski, Moshe; Strassman, Andrew M.

2007-01-01

54

Degranulation of eosinophilic granular cells with possible involvement in neutrophil migration to site of inflammation in tilapia  

Microsoft Academic Search

Observations were made on stretched preparations from the swim bladder and peritoneum obtained from tilapia (Oreochromis niloticus) after injection of formalin-killed Escherichia coli, proteose peptone, compound 48\\/80 or HBSS into the swim bladder. The eosinophilic granular cells (EGCs) in the swim bladder degranulated rapidly after inoculation. However, the peritoneal EGCs did not degranulate, indicating that degranulation occurs only at the

Tomomasa Matsuyama; Takaji Iida

1999-01-01

55

Methoxychlor enhances degranulation of murine mast cells by regulating Fc?RI-mediated signal transduction.  

PubMed

Abstract Methoxychlor, an organochlorine insecticide developed to replace DDT (dichlorodiphenyltrichloroethane), has been reported to induce mast cell degranulation and to enhance IgE-mediated allergic responses. However, the mechanisms underlying these effects are not clear. To clarify potential mechanisms, the effects of methoxychlor on degranulation of mast cells were examined. Degranulation responses were evaluated using RBL-2H3 cells and mouse bone marrow-derived mast cells with either the antigen-induced or calcium ionophore-induced stimulation. Phosphorylation of enzymes related to signaling events associated with mast cell degranulation was analyzed by immunoblotting. Effects on vascular permeability in the passive cutaneous anaphylaxis reaction were evaluated following oral administration of methoxychlor to BALB/c mice. The results indicated that methoxychlor caused increased mast cell degranulation in the presence of antigen, whereas it had no effect on calcium ionophore-induced degranulation of RBL-2H3 cells. Immunoblot analyses demonstrated that the phosphorylation level of phosphoinositide 3-kinase (which plays a central role in mast cell signaling) was increased by methoxychlor during antigen-induced degranulation. In addition, methoxychlor activated the signaling pathway via the high-affinity IgE receptor by inducing phosphorylation of Syk and PLC?1/2, which transfer the signal for degranulation downstream. Lastly, oral administration of methoxychlor exhibited a tendency to promote vascular permeability in passive cutaneous anaphylaxis model mice. Taken together, the results here suggested that methoxychlor enhanced degranulation through Fc?RI-mediated signaling and promoted allergenic symptoms involved in mast cell degranulation. PMID:25418051

Yasunaga, Sho; Nishi, Kosuke; Nishimoto, Sogo; Sugahara, Takuya

2014-11-24

56

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

SciTech Connect

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-?, 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-?B p65 phosphorylation in human neutrophils. ? SM enhanced release of TNF-?, interleukin (IL)-6 and IL-8 from human neutrophils. ? SB203580 inhibited SM-induced priming, NF-?B p65 phosphorylation and cytokine release.

Ham, Hwa-Yong [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of)] [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of); Hong, Chang-Won, E-mail: chyj7983@hallym.ac.kr [Department of Chemical and Biological Warfare Research, The Armed Forces Medical Research Institute, Daejeon (Korea, Republic of)] [Department of Chemical and Biological Warfare Research, The Armed Forces Medical Research Institute, Daejeon (Korea, Republic of); Lee, Si-Nae [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of)] [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of); Kwon, Min-Soo [Department of Pharmacology, School of Medicine, CHA University, Seongnam (Korea, Republic of)] [Department of Pharmacology, School of Medicine, CHA University, Seongnam (Korea, Republic of); Kim, Yeon-Ja [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of)] [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of); Song, Dong-Keun, E-mail: dksong@hallym.ac.kr [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of)] [Department of Pharmacology, Infectious Diseases Medical Research Center, College of Medicine, Hallym University, Chuncheon (Korea, Republic of)

2012-01-01

57

Technical Advance: Soluble OX40 molecule mimics regulatory T cell modulatory activity on Fc?RI-dependent mast cell degranulation  

PubMed Central

Tregs play a central role in modulating Fc?RI-dependent MC effector functions in the course of the allergic response. Cellular interaction depends on the constitutive expression of OX40 on Tregs and the OX40L counterpart on MCs. Study of OX40L signaling on MCs is hampered by the need of a highly purified molecule, which triggers OX40L specifically. We now report that sOX40 mimics the physiological activity of Treg interaction by binding to activated MCs. When treated with sOX40, activated MCs showed decreased degranulation and Ca++ influx, whereas PLC-?2 phosphorylation remained unaffected. Once injected into experimental animals, sOX40 not only located within the endothelium but also in parenchyma, where it could be found in close proximity and apparently bound to MCs. This soluble molecule triggers MC-OX40L without the requirement of Tregs, thus allowing study of OX40L signaling pathways in MCs and in other OX40L-expressing cell populations. Importantly, as sOX40 inhibits MC degranulation, it may provide an in vivo therapeutic tool in allergic disease. PMID:21653238

Sibilano, Riccardo; Gri, Giorgia; Frossi, Barbara; Tripodo, Claudio; Suzuki, Ryo; Rivera, Juan; MacDonald, Andrew S.; Pucillo, Carlo E.

2011-01-01

58

CD4+CD25+ regulatory T cells suppress mast cell degranulation and allergic responses through OX40-OX40L interaction  

PubMed Central

Summary CD4+CD25+ T regulatory cells (Tregs) play a central role in the suppression of immune responses thus serving to induce tolerance and to control persistent immune responses that can lead to autoimmunity. Here we explore if Tregs also play a role in controlling the immediate hypersensitivity response of mast cells (MCs). Tregs directly inhibit the Fc?RI-dependent degranulation of MCs through cell-cell contact involving OX40-OX40L interactions between Tregs and MCs, respectively. MCs show increased cAMP levels and reduced Ca2+ influx, independent of PLC-?2 or Ca2+ release from intracellular stores. Antagonism of cAMP in MCs reverses the inhibitory effects of Tregs restoring normal Ca2+ responses and degranulation. Importantly, the in vivo depletion or inactivation of Tregs causes enhancement of the anaphylactic response. The demonstrated cross-talk between Tregs and MCs defines a previously unrecognized mechanism controlling MCs degranulation. Loss of this interaction may contribute to the severity of allergic responses. PMID:18993084

Gri, Giorgia; Piconese, Silvia; Frossi, Barbara; Manfroi, Vanessa; Merluzzi, Sonia; Tripodo, Claudio; Viola, Antonella; Odom, Sandra; Rivera, Juan; Colombo, Mario P.; Pucillo, Carlo E.

2008-01-01

59

PUVA-induced Repigmentation of Vitiligo: Scanning Electron Microscopy of Hair Follicles  

Microsoft Academic Search

PUVA-induced repigmentation of vitiligo was studied using both the split-dopa reaction and scanning electron microscopy. Proliferation of hypertrophic, Dopa-positive melanocytes were observed in the lower portion of some hair follicles, whereas other giant melanocytes were observed along the middle portion. The existence of a melanocyte reservoir in human hair follicles is postulated.

J. P. Ortonne; D. Schmitt; J. Thivolet

1980-01-01

60

ORAI1-mediated calcium influx is required for human cytotoxic lymphocyte degranulation and target cell lysis.  

PubMed

Lymphocytes mediate cytotoxicity by polarized release of the contents of cytotoxic granules toward their target cells. Here, we have studied the role of the calcium release-activated calcium channel ORAI1 in human lymphocyte cytotoxicity. Natural killer (NK) cells obtained from an ORAI1-deficient patient displayed defective store-operated Ca(2+) entry (SOCE) and severely defective cytotoxic granule exocytosis leading to impaired target cell lysis. Similar findings were obtained using NK cells from a stromal interaction molecule 1-deficient patient. The defect occurred at a late stage of the signaling process, because activation of leukocyte functional antigen (LFA)-1 and cytotoxic granule polarization were not impaired. Moreover, pharmacological inhibition of SOCE interfered with degranulation and target cell lysis by freshly isolated NK cells and CD8(+) effector T cells from healthy donors. In addition to effects on lymphocyte cytotoxicity, synthesis of the chemokine macrophage inflammatory protein-1? and the cytokines TNF-? and IFN-? on target cell recognition was impaired in ORAI1-deficient NK cells, as previously described for T cells. By contrast, NK cell cytokine production induced by combinations of IL-12, IL-15, and IL-18 was not impaired by ORAI1 deficiency. Taken together, these results identify a critical role for ORAI1-mediated Ca(2+) influx in granule exocytosis for lymphocyte cytotoxicity as well as for cytokine production induced by target cell recognition. PMID:21300876

Maul-Pavicic, Andrea; Chiang, Samuel C C; Rensing-Ehl, Anne; Jessen, Birthe; Fauriat, Cyril; Wood, Stephanie M; Sjöqvist, Sebastian; Hufnagel, Markus; Schulze, Ilka; Bass, Thilo; Schamel, Wolfgang W; Fuchs, Sebastian; Pircher, Hanspeter; McCarl, Christie-Ann; Mikoshiba, Katsuhiko; Schwarz, Klaus; Feske, Stefan; Bryceson, Yenan T; Ehl, Stephan

2011-02-22

61

The src Homology 2-Containing Inositol Phosphatase (SHIP) is the Gatekeeper of Mast Cell Degranulation  

Microsoft Academic Search

To clarify the role that the src homology 2-containing inositol phosphatase (SHIP) plays in mast cell degranulation, the gene for SHIP was disrupted by homologous recombination in embryonic stem cells. Bone-marrow-derived mast cells from SHIP+\\/+, +\\/-, and -\\/- F2 littermates were compared. SHIP-\\/- mast cells were found to be far more prone to degranulation, after the crosslinking of IgE preloaded

Michael Huber; Cheryl D. Helgason; Jacqueline E. Damen; Ling Liu; R. Keith Humphries; Gerald Krystal

1998-01-01

62

Studies on the Specific Degranulation of Mast Cell Sensitized by Several Allergens in Vitro  

PubMed Central

Food allergy is a major health issue worldwide. Mast cells play a very important role in the immediate hypersensitivity for which mast cell degranulation needs to be studied extensively. In this study, an approach was taken to study the characteristics of sensitized mast cell degranulation in vitro, which associated with the study of mast cells and animal models. BALB/c mice were immunized respectively by several food allergens, then blood and peritoneal mast cells were collected at different time points. A dynamic determination was carried out between mast cells and serumal IgE. Comparative analysis on sequential time points showed that there was a close coincidence between mast cell degranulation and IgE antibody titers in sensitized BALB/c mice. Furthermore, it is interesting that sensitized mast cells could implement specific degranulation against the challenges in vitro, but the closely tropomyosins induced mast cell degranulation displayed cross reactions. This is very similar to IgE resisting the allergens in vivo. The study disclosed some characteristics on mast cells, coming from sensitized BALB/c mice, degranulation in vitro. PMID:19403066

Guo, Yongchao; Li, Zhenxing; Lin, Hong; Samee, Haider; Khalid, Jamil

2009-01-01

63

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

NASA Astrophysics Data System (ADS)

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.

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

1994-07-01

64

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

SciTech Connect

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.

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

1985-04-01

65

Flow microfluorometric analysis of phagocyte degranulation in bacteria-infected whole human blood cell cultures  

NASA Astrophysics Data System (ADS)

A quantitative flow microfluorometric method was used to study the intensity of human blood phagocyte degranulation in response to viable staphylococcus aureus or Yersinia pestis cells. Microorganisms were added directly to defibrinated whole blood. Uninfected and infected blood samples were incubated at 37 degrees C to 8 h. The results were recorded in dynamics after the staining of whole blood with acridine orange solution. Lymphocytes with a low azurophilic granule per cell content were discriminated from phagocytes by the measurement of single cell red cytoplasmic granule fluorescence. 30,000 cells in each sample were examined. S. aureus cells caused a dose-dependent decrease in the number of phagocytes having a high red cytoplasmic fluorescence intensity and a corresponding increase in the weakly fluorescence cell population. In the presence of an initial S. aureus-to-phagocyte ratio more than 1:1, degranulation was measured after 3 h of incubation and to 8 h the percentage of degranulated phagocytes was at least 100 percent Y. pestis cells grown for 48 h at 28 degrees C caused at same condition as the degranulation only about 50 percent of cells. Y.pestis EV cells preincubated in broth for 12 h at 37 degrees C did no stimulate the phahocyte degranulation. The results of these studies suggest that analysis of cell populations via flow microfluorimeter technology may be a powerful tool in analysis bacterial infection.

Kravtsov, Alexander L.; Bobyleva, Elena V.; Grebenyukova, Tatyana P.; Kuznetsov, Oleg S.; Kulyash, Youri V.

2002-07-01

66

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

SciTech Connect

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.

Bredberg, A.

1981-06-01

67

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

NASA Astrophysics Data System (ADS)

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.

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

2009-08-01

68

PUVA bath therapy strongly suppresses immunological and epidermal activation in psoriasis: a possible cellular basis for remittive therapy  

PubMed Central

Psoriasis is characterized by alterations in both the epidermis and dermis of the skin. Epidermal keratinocytes display marked proliferative activation and differentiate along an "alternate" or "regenerative" pathway, while the dermis becomes infiltrated with leukocytes, particularly interleukin 2 (IL-2) receptor-bearing "activated" T cells. Psoralens, administered by the oral route, have therapeutic effects in psoriasis when photochemically activated by ultraviolet A light (PUVA therapy). Recently psoralen bath therapy has been introduced to more effectively deliver this agent to the diseased skin. We have correlated the efficacy of PUVA bath therapy with its effects on specific molecular and cellular parameters of disease, in 10 consecutive patients with recalcitrant psoriasis. Rapid clearing of lesions occurred in 8 out of 10 patients. Biopsies were taken from lesional and nonlesional skin before and after a single round of therapy, and observation was continued in our Clinical Research Center at The Rockefeller University. Enumeration of cycling keratinocytes with the Ki-67 monoclonal antibody showed that PUVA reduced cell proliferation by 73%. The pathological increase in insulin-like growth factor 1 (IGF-1) receptors was reversed, whereas epidermal growth factor (EGF) receptors, which are also increased in psoriasis, remained unchanged. Keratinocyte proteins that are expressed in abnormal sites of the epidermis during psoriasis, i.e., keratin 16, filaggrin, and involucrin, were, after PUVA treatment, localized to their normal sites. Epidermal and dermal T-lymphocytes (CD3+), as well as CD4+, CD8+, and IL-2 receptor+ subsets, were strongly suppressed by PUVA, with virtual elimination of IL-2 receptor+ T cells in some patients. Consistent with diminished lymphocyte activation, HLA-DR expression by epidermal keratinocytes was markedly reduced in treated skin. In comparison to cyclosporine treatment of psoriasis, PUVA therapy leads to more complete reversal of pathological epidermal and lymphocytic activation, changes which we propose to be the cellular basis for a more sustained remission of disease after PUVA treatment. PMID:7516410

1994-01-01

69

Degranulation of human mast cells induces an endothelial antigen central to leukocyte adhesion.  

PubMed Central

To understand better the role of mast cell secretory products in the genesis of inflammation, a system was developed for in vitro degranulation of human mast cells in skin organ cultures. Within 2 hr after morphine sulfate-induced degranulation, endothelial cells lining microvessels adjacent to affected mast cells expressed an activation antigen important for endothelial-leukocyte adhesion. Identical results were obtained when other mast cell secretagogues (anti-IgE, compound 48/80, and calcium ionophore A23187) were used. Induction of this antigen was abrogated by preincubation with cromolyn sodium, an inhibitor of mast cell secretion, and by antiserum to tumor necrosis factor alpha. These findings indicate that degranulation of mast cells activates dermal endothelium through tumor necrosis factor-dependent mechanisms. This event may be critical to the elicitation phase of cutaneous inflammation. Images PMID:2479033

Klein, L M; Lavker, R M; Matis, W L; Murphy, G F

1989-01-01

70

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

NASA Astrophysics Data System (ADS)

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.

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

1998-07-01

71

Widespread Cutaneous Carcinomas Associated with Human Papillomaviruses 5, 14 and 20 after Introduction of Methotrexate in Two Long-Term PUVA-Treated Patients  

Microsoft Academic Search

Background: PUVA treatment for patients with severe psoriasis has been demonstrated to be highly effective. However, an increased risk of nonmelanoma and melanoma skin cancers has been reported. It is generally accepted that the risk of squamous-cell carcinoma (SCC) is significantly increased in patients with long-term PUVA therapy. The role of methotrexate (MTX) and infection with oncogenic human papillomaviruses which

Ulf Zumtobel; Hartmut P. Schwarze; Michel Favre; Alain Taïeb; Michèle Delaunay

2001-01-01

72

Effects of In Vitro UVA Irradiation and PUVA Treatment on Membrane Fatty Acids and Activities of Antioxidant Enzymes in Human Keratinocytes  

Microsoft Academic Search

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

Kari Punnonen; Christer T. Jansen; Antti Puntala; Markku Ahotupa

1991-01-01

73

Influence of physicochemical properties of silver nanoparticles on mast cell activation and degranulation.  

PubMed

Silver nanoparticles (AgNPs) are increasingly being incorporated into products for their antimicrobial properties. This has resulted in increased human exposures and the possibility of adverse health effects. Mast cells orchestrate allergic immune responses through degranulation and release of pre-formed mediators. Little data exists on understanding interactions of AgNPs with mast cells and the properties that influence activation and degranulation. Using bone marrow-derived mast cells and AgNPs of varying physicochemical properties we tested the hypothesis that AgNP physicochemical properties influence mast cell degranulation and osteopontin production. AgNPs evaluated included spherical 20 nm and 110 nm suspended in either polyvinylpyrrolidone (PVP) or citrate, Ag plates suspended in PVP of diameters between 40–60 nm or 100–130 nm, and Ag nanowires suspended in PVP with thicknesses <100 nm and length up to 2 ?m. Mast cell responses were found to be dependent on the physicochemical properties of the AgNP. Further, we determined a role for scavenger receptor B1 in AgNP-induced mast cell responses. Mast cell degranulation was not dependent on AgNP dissolution but was prevented by tyrosine kinase inhibitor pretreatment. This study suggests that exposure to AgNPs may elicit adverse mast cell responses that could contribute to the initiation or exacerbation of allergic disease. PMID:25458489

Aldossari, Abdullah A; Shannahan, Jonathan H; Podila, Ramakrishna; Brown, Jared M

2015-02-01

74

Defective cytotoxic lymphocyte degranulation in syntaxin-11–deficient familial hemophagocytic lymphohistiocytosis 4 (FHL4) patients  

PubMed Central

Familial hemophagocytic lymphohistiocytosis (FHL) is typically an early onset, fatal disease characterized by a sepsislike illness with cytopenia, hepatosplenomegaly, and deficient lymphocyte cytotoxicity. Disease-causing mutations have been identified in genes encoding perforin (PRF1/FHL2), Munc13-4 (UNC13D/FHL3), and syntaxin-11 (STX11/FHL4). In contrast to mutations leading to loss of perforin and Munc13-4 function, it is unclear how syntaxin-11 loss-of-function mutations contribute to disease. We show here that freshly isolated, resting natural killer (NK) cells and CD8+ T cells express syntaxin-11. In infants, NK cells are the predominant perforin-containing cell type. NK cells from FHL4 patients fail to degranulate when encountering susceptible target cells. Unexpectedly, IL-2 stimulation partially restores degranulation and cytotoxicity by NK cells, which could explain the less severe disease progression observed in FHL4 patients, compared with FHL2 and FHL3 patients. Since the effector T-cell compartment is still immature in infants, our data suggest that the observed defect in NK-cell degranulation may contribute to the pathophysiology of FHL, that evaluation of NK-cell degranulation in suspected FHL patients may facilitate diagnosis, and that these new insights may offer novel therapeutic possibilities. PMID:17525286

Bryceson, Yenan T.; Rudd, Eva; Zheng, Chengyun; Edner, Josefine; Ma, Daoxin; Wood, Stephanie M.; Bechensteen, Anne Grete; Boelens, Jaap J.; Celkan, Tiraje; Farah, Roula A.; Hultenby, Kjell; Winiarski, Jacek; Roche, Paul A.; Nordenskjöld, Magnus

2007-01-01

75

Staphylococcus ?-toxin promotes mouse allergic skin disease by inducing mast cell degranulation  

PubMed Central

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects 15 to 30% of children and ~5% of adults in industrialized countries1. Although the pathogenesis of AD is not fully understood, the disease is mediated by an abnormal immunoglobulin E (IgE) immune response in the setting of skin barrier dysfunction2. Mast cells (MCs) contribute to IgE-mediated allergic disorders including AD3. Upon activation, MCs release their membrane-bound cytosolic granules leading to the release of multiple molecules that are important in the pathogenesis of AD and host defense4. More than 90% of AD patients are colonized with Staphylococcus aureus in the lesional skin whereas most healthy individuals do not harbor the pathogen5. Several Staphylococcal exotoxins (SEs) can act as superantigens and/or antigens in models of AD6. However, the role of these SEs in disease pathogenesis remains unclear. Here, we report that culture supernatants of S. aureus contain potent MC degranulation activity. Biochemical analysis identified ?-toxin as the MC degranulation-inducing factor produced by S. aureus. MC degranulation induced by ?-toxin depended on phosphoinositide 3-kinase (PI3K) and calcium (Ca2+) influx, but unlike that mediated by IgE crosslinking, it did not require the spleen tyrosine kinase (Syk). In addition, IgE enhanced ?-toxin-induced MC degranulation in the absence of antigen. Furthermore, S. aureus isolates recovered from AD patients produced high levels of ?-toxin. Importantly, skin colonization with S. aureus, but not a mutant deficient in ?-toxin, promoted IgE and IL-4 production, as well as inflammatory skin disease. Furthermore, enhancement of IgE production and dermatitis by ?-toxin was abrogated in KitW-sh/W-sh MC-deficient mice and restored by MC reconstitution. These studies identify ?-toxin as a potent inducer of MC degranulation and suggest a mechanistic link between S. aureus colonization and allergic skin disease. PMID:24172897

Nakamura, Yuumi; Oscherwitz, Jon; Cease, Kemp B.; Chan, Susana M.; Muñoz-Planillo, Raul; Hasegawa, Mizuho; Villaruz, Amer E.; Cheung, Gordon Y. C.; McGavin, Martin J.; Travers, Jeffrey B.; Otto, Michael; Inohara, Naohiro; Núñez, Gabriel

2013-01-01

76

Differential analysis of experimental hypermelanosis induced by UVB, PUVA, and allergic contact dermatitis using a brownish guinea pig model  

Microsoft Academic Search

In moderately colored guinea-pig skin, UVB, PUVA, and allergic contact dermatitis were shown to induce hyperpigmentation that resembled the pigmentary changes observed in mongoloid human skin. Using this model, we examined the effects of chemical agents, including tyrosinase inhibitors and sunscreen agents, on the color changes induced by UV irradiation. The daily exposure of brownish guinea-pig skin to UVB irradiation

G. Imokawa; M. Kawai; Y. Mishima; I. Motegi

1986-01-01

77

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

SciTech Connect

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.

Malinin, G.I.; Lo, H.K.; Hornicek, F.J.; Malinin, T.I. (Georgetown Univ., Washington, DC (USA))

1990-07-01

78

Cost-Effectiveness Analysis Comparing Methotrexate With PUVA Therapy for Moderate—Severe Psoriasis in the Sanitary Area of Badajoz  

Microsoft Academic Search

ObjectiveTo perform a cost-effectiveness analysis, by using a decision tree model, comparing methotrexate with PUVA therapy for moderate to severe chronic plaque psoriasis in the sanitary area of Badajoz (south-western Spain) over a one-year period.

D. de Argila; I. Rodríguez-Nevado; A. Chaves

2007-01-01

79

Diminished allergic disease in patients with STAT3 mutations reveals a role for STAT3 signaling in mast cell degranulation  

PubMed Central

Background Severe atopic conditions associated with elevated serum IgE are heterogeneous with few known causes. Nearly every patient with autosomal-dominant hyper-IgE syndrome (AD-HIES) due to signal transducer and activator of transcription 3 (STAT3) mutations has a history of eczematous dermatitis and elevated IgE; however, clinical atopy has never been systematically studied. Objective Understanding of genetic determinants of allergic disease may lead to novel therapies in controlling allergic disease. Methods We conducted clinical evaluation of the rates of food allergies and anaphylaxis in patients with AD-HIES, a cohort of patients with no STAT3 mutation but with similar histories of elevated IgE and atopic dermatitis, and healthy volunteers with no history of atopy. Morphine skin prick testing, ImmunoCAP assays for allergen-specific IgE, and basophil activation were measured. A model of systemic anaphylaxis was studied in transgenic mice carrying an AD-HIES mutation. STAT3 was silenced in LAD2 and primary human mast cells to study the role of STAT3 in signaling and degranulation after IgE cross-linking. Results Food allergies and anaphylaxis were markedly diminished in patients with AD-HIES compared with a cohort of patients with no STAT3 mutation but with similar histories of elevated IgE and atopic dermatitis. Morphine skin prick testing and basophil activation were diminished in patients with AD-HIES, whereas mice carrying an AD-HIES mutation were hyporesponsive to systemic anaphylaxis models. Rapid mast cell STAT3 serine727 phosphorylation was noted after IgE cross-linking, and inhibition of STAT3 signaling in mast cells lead to impaired Fc?RI-mediated proximal and distal signaling, as well as reduced degranulation. Conclusion This study serves as an example for how mutations in specific atopic pathways can lead to discrete allergic phenotypes, encompassing increased risk of some phenotypes but a relative protection from others. PMID:24184145

Siegel, Andrea M.; Stone, Kelly D.; Cruse, Glenn; Lawrence, Monica G.; Olivera, Ana; Jung, Mi-yeon; Barber, John S.; Freeman, Alexandra F.; Holland, Steven M.; O’Brien, Michelle; Jones, Nina; Wisch, Laura B.; Kong, Heidi H.; Desai, Avanti; Farber, Orly; Gilfillan, Alasdair M.; Rivera, Juan; Milner, Joshua D.

2013-01-01

80

Singlet oxygen generation in PUVA therapy studied using electronic structure calculations  

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

81

Prevention of F-actin assembly switches the response to SCF from chemotaxis to degranulation in human mast cells.  

PubMed

Following antigen/IgE-mediated aggregation of high affinity IgE-receptors (Fc?RI), mast cells (MCs) degranulate and release inflammatory mediators leading to the induction of allergic reactions including anaphylaxis. Migration of MCs to resident tissues and sites of inflammation is regulated by tissue chemotactic factors such as stem cell factor (SCF (KIT ligand)). Despite inducing similar early signaling events to antigen, chemotactic factors, including SCF, produce minimal degranulation in the absence of other stimuli. We therefore investigated whether processes regulating MC chemotaxis are rate limiting for MC mediator release. To investigate this issue, we disrupted actin polymerization, a requirement for MC chemotaxis, with latrunculin B and cytochalasin B, then examined chemotaxis and mediator release in human (hu)MCs induced by antigen or SCF. As expected, such disruption minimally affected early signaling pathways, but attenuated SCF-induced human mast cell chemotaxis. In contrast, SCF, in the absence of other stimuli, induced substantial degranulation in a concentration-dependent manner following actin disassembly. It also moderately enhanced antigen-mediated human mast cell degranulation which was further enhanced in the presence of SCF. These observations suggest that processes regulating cell migration limit MC degranulation as a consequence of cytoskeletal reorganization. PMID:23616175

Smrž, Daniel; Bandara, Geethani; Beaven, Michael A; Metcalfe, Dean D; Gilfillan, Alasdair M

2013-07-01

82

Prevention of F-actin assembly switches the response to SCF from chemotaxis to degranulation in human mast cells  

PubMed Central

Summary Following antigen/IgE-mediated aggregation of high affinity IgE-receptors (Fc?RI), mast cells (MCs) degranulate and release inflammatory mediators leading to the induction of allergic reactions including anaphylaxis. Migration of MCs to resident tissues and sites of inflammation is regulated by tissue chemotactic factors such as stem cell factor (SCF [KIT ligand]). Despite inducing similar early signaling events to antigen, chemotactic factors, including SCF, produce minimal degranulation in the absence of other stimuli. We therefore investigated whether processes regulating MC chemotaxis are rate limiting for MC mediator release. To investigate this issue, we disrupted actin polymerization, a requirement for MC chemotaxis, with latrunculin B and cytochalasin B, then examined chemotaxis and mediator release in human (hu)MCs induced by antigen or SCF. As expected, such disruption minimally affected early signaling pathways, but attenuated SCF-induced huMC chemotaxis. In contrast, SCF, in the absence of other stimuli, induced substantial degranulation in a concentration-dependent manner following actin disassembly. It also moderately enhanced antigen-mediated huMC degranulation which was further enhanced in the presence of SCF. These observations suggest that processes regulating cell migration limit MC degranulation as a consequence of cytoskeletal reorganization. PMID:23616175

Smrž, Daniel; Bandara, Geethani; Beaven, Michael A.; Metcalfe, Dean D.; Gilfillan, Alasdair M.

2013-01-01

83

cis-urocanic acid induces mast cell degranulation and release of preformed TNF-alpha: A possible mechanism linking UVB and cis-urocanic acid to immunosuppression of contact hypersensitivity.  

PubMed

The search for effective inhibitors of transdermal drug-induced contact sensitization was directed to dermal mast-cell-degranulating agents (MCDA). Human skin organ cultures were employed to test whether cis-urocanic acid (C-UA) and other potential MCDAs cause mast cell degranulation. These were then tested for their ability to inhibit the induction phase of the contact hypersensitivity reaction (CHR). C-UA at 1 microg/ml significantly depleted mast cell chymase, whereas trans-urocanic acid (T-UA) was relatively ineffective. C-UA, but not T-UA, induced local effects of liberated mast cell TNF-alpha, as detected by E-selectin expression on the microvascular dermal endothelium. C-UA significantly reduced (>70%) the ear swelling response in Balb/c mice, when applied 24 h prior to application of a sensitizing amount of dinitrochlorobenzene (DNCB), and induced a prolonged (>3 weeks) state of immune tolerance (>40%). Similar effects on local immunosuppression of CHR were observed with topical chloroquine and capsaicin, while cromolyn, a mast cell membrane stabilizer, was unable to inhibit DNCB-induced CHR. It is suggested that MCDAs may interfere with downstream events associated with accessory cell function. PMID:10325580

Wille, J J; Kydonieus, A F; Murphy, G F

1999-01-01

84

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

PubMed

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 (?), 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 heterogeneity) reduction is consistent with the biological informative content decrease, due to granule content depletion. In spite of the significant differences in fractal dimension and lacunarity values registered according to the analysed feature (greyscale obtained values were, on average, lower than those obtained from outlines and skeletons; General Linear Model, p < 0.01), the discrimination power between not degranulated and degranulated MCs was, on average, the same and fully comparable with previously performed texture analysis on the same experimental material (outline and skeleton misclassification error, 20% [two false negative cases]; greyscale misclassification error, 30% [two false negative cases and one false positive case]). Fractal analysis proved to be a reliable and objective method for the characterization of MCs degranulation. PMID:25087582

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

2014-11-01

85

Apoptosis, mast cell degranulation and collagen breakdown in the pathogenesis of loxoscelism in subcutaneously implanted sponges.  

PubMed

Envenomation by the Loxosceles spider causes loxoscelism, a pattern of signs and symptoms that primarily manifests in the dermonecrotic form. Our studies have shown that a mouse subcutaneous sponge implantation model may be useful in evaluating the effects of Loxosceles similis venom. This model provides an ideal microenvironment in which to study loxoscelism; however, it is still important to evaluate its pathogenesis and to observe the effects of L. similis venom for longer time periods than those in previous studies of this model. The aims of this study are: (1) to histologically characterize the effects of L. similis crude venom in a subcutaneous sponge implant; (2) to quantify the mast cells present in the implant and to measure their degranulation activity; (3) to quantify collagen subtypes I and III; and (4) to verify, quantify, and evaluate the effects of apoptosis in the implant on the pathogenesis of loxoscelism at 1 h, 4 h, and 24 h after injecting the venom. Thirty Swiss mice (6-8 weeks old, male) were subcutaneously implanted with polyester-polyurethane sponge discs. Fourteen days post-implantation, the animals were divided into six groups (5 animals per group): three control groups (C1h, C4h, and C24h), in which the mice received 30 ?l injections of intra-implant saline, and three treated groups (T1h, T4h, and T24h), in which the mice received 30 ?l (0.5 ?g) injections of L. similis crude venom at 1 h, 4 h, and 24 h intervals. After each time interval, the animals were euthanized, and the implants were harvested and processed for light and electron microscopic analyses. The following results were observed in the implants harvested from the treated groups: acute inflammation with marked edema, thrombus, and vasculitis, as well as increased levels of mast cells and mast cell degranulation, and apoptosis in giant cells. Furthermore, degradation of collagen types I and III was observed. An analysis of the ultrastructure revealed apoptosis in various cell types. The present results suggest that apoptosis in some cell types associated with an increase in mast cell degranulation and the degradation of collagen fibers are important in the pathogenesis of loxoscelism therefore may explain the difficulty in repairing the ulcer is commonly observed in severe cases of loxoscelism cutaneous in humans. PMID:24657389

Pereira, Núbia Braga; Campos, Paula Peixoto; Parreiras, Patrícia Martins; Chiarini-Garcia, Hélio; Socarrás, Teresa Oviedo; Kalapothakis, Evanguedes; Andrade, Silvia Passos; Moro, Luciana

2014-06-01

86

Immature DC isolated after co-culture with PUVA-treated peripheral blood mononuclear cells downregulate graft-versus-host reactions in the human skin explant model.  

PubMed

Graft-versus-host disease (GvHD) remains the major barrier to successful allogeneic hematopoietic stem cell transplantation (HSCT). Extracorporeal photopheresis (ECP) is a potent immunomodulatory treatment option for GvHD. In contrast to conventional immunosuppressants, ECP is considered not to increase relapse and infection rates resulting from generalised immunosuppression. ECP involves the mechanical separation of 5-10% of patient peripheral blood mononuclear cells, which are then exposed to psoralen and UVA light (PUVA) before they are returned to the patient. ECP has been shown to induce apoptosis in various cell types, in particular lymphocytes. Several studies describe downregulation of pro-inflammatory cytokines as well as promotion of peripheral tolerance through enhanced production of T regulatory cells in the course of ECP-treatment. Modulation of antigen-presenting cells such as dendritic cells (DC) by PUVA-treated lymphocytes might be implicated in these regulatory processes. We evaluated the impact of PUVA-treated lymphocytes on immature DC and further demonstrated the functional capacity of such modified DC to modulate GVH reactions using a well-established human skin-explant model of GvHD. Addition of immature DC isolated after co-culture with PUVA-treated but not untreated MLR cells significantly downregulated skin-GvH reactions (p=0.023, Mann-Whitney-Test). IFN-gamma levels were non-significantly decreased in MLR and skin supernatants. We observed a non-significant increase in PD-L1 expression in iDC after co-culture with PUVA-treated MLR cells whereas expression levels of IDO and ILT-3 were not affected. We conclude that iDC modulated by PUVA-induced apoptotic cells potently downregulate allogeneic immune responses possibly through PD-L1- dependent signaling. PMID:23363467

Holtick, Udo; Wang, Xiao N; Marshall, Scott R; Scheid, Christof; von Bergwelt-Baildon, Michael; Dickinson, Anne M

2013-07-01

87

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

NASA Astrophysics Data System (ADS)

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.

Diffey, Brian

2006-07-01

88

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

SciTech Connect

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.

Viola, Giampietro [Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, 35131 Padova (Italy)], E-mail: giampietro.viola.1@unipd.it; Fortunato, Elena; Cecconet, Laura; Del Giudice, Laura [Department of Pediatrics, University of Padova, via Giustiniani 3, Padova (Italy); Dall'Acqua, Francesco [Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, 35131 Padova (Italy); Basso, Giuseppe [Department of Pediatrics, University of Padova, via Giustiniani 3, Padova (Italy)

2008-02-15

89

UVA/UVA1 phototherapy and PUVA photochemotherapy in connective tissue diseases and related disorders: a research based review  

PubMed Central

Background Broad-band UVA, long-wave UVA1 and PUVA treatment have been described as an alternative/adjunct therapeutic option in a number of inflammatory and malignant skin diseases. Nevertheless, controlled studies investigating the efficacy of UVA irradiation in connective tissue diseases and related disorders are rare. Methods Searching the PubMed database the current article systematically reviews established and innovative therapeutic approaches of broad-band UVA irradiation, UVA1 phototherapy and PUVA photochemotherapy in a variety of different connective tissue disorders. Results Potential pathways include immunomodulation of inflammation, induction of collagenases and initiation of apoptosis. Even though holding the risk of carcinogenesis, photoaging or UV-induced exacerbation, UVA phototherapy seems to exhibit a tolerable risk/benefit ratio at least in systemic sclerosis, localized scleroderma, extragenital lichen sclerosus et atrophicus, sclerodermoid graft-versus-host disease, lupus erythematosus and a number of sclerotic rarities. Conclusions Based on the data retrieved from the literature, therapeutic UVA exposure seems to be effective in connective tissue diseases and related disorders. However, more controlled investigations are needed in order to establish a clear-cut catalogue of indications. PMID:15380024

Breuckmann, Frank; Gambichler, Thilo; Altmeyer, Peter; Kreuter, Alexander

2004-01-01

90

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

SciTech Connect

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.

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

1985-03-01

91

Loss of TRPC1-mediated Ca2+ influx contributes to impaired degranulation in Fyn-deficient mouse bone marrow-derived mast cells  

PubMed Central

MC degranulation requires the influx of calcium from the extracellular environment. Orai1/STIM1 is essential to MC SOCE, as shown in rat peritoneal MCs, the rat MC lines (RBL-2H3), or in Orai1 null embryo liver-derived, cultured MCs. However, minimal information exists about the role of other calcium channels expressed on these cells. Here, we demonstrate that the nonselective TRPC1 participates in Fc?RI-mediated calcium entry in mouse BMMCs. We found that Fyn null MCs, which have an impaired degranulation response, expressed reduced levels of TRPC1, had normal depletion of intracellular calcium stores but an impaired calcium influx, and failed to depolymerize cortical F-actin (a key step for granule-plasma membrane fusion). Partial RNAi silencing of TRPC1 expression in WT MCs (to the level of Fyn null MCs) mimicked the Fyn null defect in calcium influx, cortical F-actin depolymerization, and MC degranulation. Ectopic expression of Fyn or TRPC1 in Fyn null MCs restored calcium responses and cortical F-actin depolymerization and increased MC degranulation. Together with our findings that expression of Orai1 is not altered in Fyn null MCs, our findings suggest that TRPC1 participates in calcium influx and other key events required for MC degranulation. This demonstrates that in addition to a role described previously for Orai1 in promoting MC degranulation, nonselective cation channels participate in promoting the exocytotic response. PMID:20571036

Suzuki, Ryo; Liu, Xibao; Olivera, Ana; Aguiniga, Lizath; Yamashita, Yumi; Blank, Ulrich; Ambudkar, Indu; Rivera, Juan

2010-01-01

92

Evaluation of PUVA-Induced Skin Side Effects in Patients Referred to the Imam Reza Hospital of Mashhad in 2005-2007  

PubMed Central

Background: Systemic oral psoralens plus UVA therapy (PUVA) is a therapeutic method used with considerable success in many different skin disorders. PUVA therapy causes some cutaneous and noncutaneous side effects and in the present research we deal with cutaneous side effects. Aims: Evaluation of patients to know the different skin side effects of PUVA and their importance. Materials and Methods: All patients referred to the phototherapy unit of Imam Reza Hospital of Mashhad entered the research and skin examination was taken place initially and every 3 months thereafter. Whenever any side effect appeared, it was recorded in the information sheet. Results: One hundred and twenty-eight patients were included in the research, 61 were male between 15 and 75 years and 67 were female between 10 and 61 years of age. Age of female patients at the time of cutaneous side effect appearance was less than male patients. The most common early side effect was pruritus (34.3%) and the rarest was telangiectasia (0.7%). One case of late side effect in the form of squamous cell carcinoma was observed in a patient who had received other carcinogenic drugs as well. Complications such as skin dryness, pruritus, erythema and burning sensation occurred at low doses of UVA, while dermatitis, severe limb pain and acne at moderate doses and PUVA lentigines, hypertrichosis and lichenoid lesions appeared at high doses of UVA. Conclusion: Considering the significant therapeutic effects and few serious side effects, PUVA therapy is a suitable and safe method for treatment of certain skin diseases. PMID:24700955

Maleki, Masoud; Yazdanpanah, Mohammad Javad; Hamidi, Hamid; Jokar, Leila

2014-01-01

93

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

PubMed Central

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

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

94

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

PubMed

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

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; Reeves, Emer P; McElvaney, Noel G

2014-08-14

95

A worm's best friend: recruitment of neutrophils by Wolbachia confounds eosinophil degranulation against the filarial nematode Onchocerca ochengi.  

PubMed

Onchocerca ochengi, a filarial parasite of cattle, represents the closest relative of the human pathogen, Onchocerca volvulus. Both species harbour Wolbachia endosymbionts and are remarkable in that adult female worms remain viable but sessile for many years while surrounded by host cells and antibodies. The basis of the symbiosis between filariae and Wolbachia is thought to be metabolic, although a role for Wolbachia in immune evasion has received little attention. Neutrophils are attracted to Wolbachia, but following antibiotic chemotherapy they are replaced by eosinophils that degranulate on the worm cuticle. However, it is unclear whether the eosinophils are involved in parasite killing or if they are attracted secondarily to dying worms. In this study, cattle infected with Onchocerca ochengi received adulticidal regimens of oxytetracycline or melarsomine. In contrast to oxytetracycline, melarsomine did not directly affect Wolbachia viability. Eosinophil degranulation increased significantly only in the oxytetracycline group; whereas nodular gene expression of bovine neutrophilic chemokines was lowest in this group. Moreover, intense eosinophil degranulation was initially associated with worm vitality, not degeneration. Taken together, these data offer strong support for the hypothesis that Wolbachia confers longevity on O. ochengi through a defensive mutualism, which diverts a potentially lethal effector cell response. PMID:21177682

Hansen, Rowena D E; Trees, Alexander J; Bah, Germanus S; Hetzel, Udo; Martin, Coralie; Bain, Odile; Tanya, Vincent N; Makepeace, Benjamin L

2011-08-01

96

A worm's best friend: recruitment of neutrophils by Wolbachia confounds eosinophil degranulation against the filarial nematode Onchocerca ochengi  

PubMed Central

Onchocerca ochengi, a filarial parasite of cattle, represents the closest relative of the human pathogen, Onchocerca volvulus. Both species harbour Wolbachia endosymbionts and are remarkable in that adult female worms remain viable but sessile for many years while surrounded by host cells and antibodies. The basis of the symbiosis between filariae and Wolbachia is thought to be metabolic, although a role for Wolbachia in immune evasion has received little attention. Neutrophils are attracted to Wolbachia, but following antibiotic chemotherapy they are replaced by eosinophils that degranulate on the worm cuticle. However, it is unclear whether the eosinophils are involved in parasite killing or if they are attracted secondarily to dying worms. In this study, cattle infected with Onchocerca ochengi received adulticidal regimens of oxytetracycline or melarsomine. In contrast to oxytetracycline, melarsomine did not directly affect Wolbachia viability. Eosinophil degranulation increased significantly only in the oxytetracycline group; whereas nodular gene expression of bovine neutrophilic chemokines was lowest in this group. Moreover, intense eosinophil degranulation was initially associated with worm vitality, not degeneration. Taken together, these data offer strong support for the hypothesis that Wolbachia confers longevity on O. ochengi through a defensive mutualism, which diverts a potentially lethal effector cell response. PMID:21177682

Hansen, Rowena D. E.; Trees, Alexander J.; Bah, Germanus S.; Hetzel, Udo; Martin, Coralie; Bain, Odile; Tanya, Vincent N.; Makepeace, Benjamin L.

2011-01-01

97

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

USGS Publications Warehouse

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.

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

2013-01-01

98

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

PubMed Central

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. PMID:21483445

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

2011-01-01

99

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

PubMed

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. PMID:23948330

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

100

Reduction of the Fraction of Circulating Helper-Induced T Cells Identified by Monoclonal Antibodies in Psoriatic Patients Treated with Long-term Psoralen\\/Ultraviolet-A Radiation (PUVA)  

Microsoft Academic Search

Ultraviolet radiation has been found to alter the distribution and function of human lymphocytes. To determine whether photochemotherapy (PUVA) alters circulating levels of T cell subset marker-bearing lymphocytes, cells from 9 patients with psoriasis undergoing PUVA therapy for several years (mean 4.6 ± 1.4 yr), 17 patients with active untreated psoriasis, and 20 healthy volunteers were reacted with monoclonal antibodies

Richard A. Moscicki; Warwick L. Morison; John A. Parrish; Kurt J. Bloch; Robert B. Colvin

1982-01-01

101

Effect of fatty acid structure on neutrophil adhesion, degranulation and damage to endothelial cells.  

PubMed

Neutrophils have been implicated in ischaemic heart disease, unstable angina pectoris and acute myocardial infarction. Alterations in dietary levels of specific 18- and 20-carbon polyunsaturated fatty acids have significant clinical benefits in cardiovascular disease. However, to date there has been no concerted effort to identify the structural basis for polyunsaturated fatty acid-induced alterations in key neutrophil functions. We have investigated the influence of fatty acid structure and involvement of lipoxygenase/cyclooxygenase pathways on fatty acid-induced neutrophil functions. When neutrophils were incubated with 18-carbon fatty acids containing one to four double bonds (10-33 mumol/l), a significant increase in adherence and release of specific granule constituents occurred compared with control cells. In general, as the number of double bonds in the 18-carbon fatty acid increased, so did its ability to stimulate these functions. There was less stimulation of adherence and specific granule release by 18:3(n-3) than its isomer 18:3(n-6). Smaller effects were seen on azurophilic granule release. A further increase in adherence and degranulation was observed with increasing carbon chain length (20:3(n-6) and 20:4(n-6)). Differences were found in the ability of isomers of 20:3 to stimulate neutrophil function. Of the fatty acids tested only 20:4(n-6) was able to induce significant neutrophil-mediated endothelial detachment. Introduction of either internal hydroperoxy or hydroxyl groups into 20:4(n-6) abolished its adherence stimulating activity and considerably reduced its ability to stimulate release of both specific and azurophilic granules. Preincubation of neutrophils with either lipoxygenase (caffeic acid) or cyclooxygenase (indomethacin) inhibitors had no effect on 20:4(n-6) stimulated function. These studies show that the number and position of double bonds, carbon chain length and oxidation state can be critical to the neutrophil stimulatory properties of these fatty acids. PMID:7575780

Bates, E J; Ferrante, A; Smithers, L; Poulos, A; Robinson, B S

1995-08-01

102

8-methoxypsoralen plus ultraviolet A therapy acts via inhibition of the IL-23/Th17 axis and induction of Foxp3+ regulatory T cells involving CTLA4 signaling in a psoriasis-like skin disorder.  

PubMed

To elucidate the molecular action of 8-methoxypsoralen plus UVA (PUVA), a standard dermatological therapy, we used K5.hTGF-beta1 transgenic mice exhibiting a skin phenotype and cytokine abnormalities with strong similarities to human psoriasis. We observed that impaired function of CD4+CD25+ regulatory T cells (Tregs) and increased cytokine levels of the IL-23/Th17 pathway were responsible for the psoriatic phenotype in this mouse model. Treatment of K5.hTGF-beta1 transgenic mice with PUVA suppressed the IL-23/Th17 pathway, Th1 milieu, as well as transcription factors STAT3 and orphan nuclear receptor RORgammat. PUVA induced the Th2 pathway and IL-10-producing CD4+CD25+Foxp3+Tregs with disease-suppressive activity that was abolished by anti-CTLA4 mAb treatment. These findings were paralleled by macroscopic and microscopic clearance of the diseased murine skin. Anti-IL-17 mAb treatment also diminished the psoriatic phenotype of the mice. This indicated that both induced Tregs involving CTLA4 signaling and inhibition of the IL-23/Th17 axis are central for the therapeutic action of PUVA. PMID:20488788

Singh, Tej Pratap; Schön, Michael P; Wallbrecht, Katrin; Michaelis, Kai; Rinner, Beate; Mayer, Gerlinde; Schmidbauer, Ulrike; Strohmaier, Heimo; Wang, Xiao-Jing; Wolf, Peter

2010-06-15

103

DOCK5 functions as a key signaling adaptor that links Fc?RI signals to microtubule dynamics during mast cell degranulation  

PubMed Central

Mast cells play a key role in the induction of anaphylaxis, a life-threatening IgE-dependent allergic reaction, by secreting chemical mediators that are stored in secretory granules. Degranulation of mast cells is triggered by aggregation of the high-affinity IgE receptor, Fc?RI, and involves dynamic rearrangement of microtubules. Although much is known about proximal signals downstream of Fc?RI, the distal signaling events controlling microtubule dynamics remain elusive. Here we report that DOCK5, an atypical guanine nucleotide exchange factor (GEF) for Rac, is essential for mast cell degranulation. As such, we found that DOCK5-deficient mice exhibit resistance to systemic and cutaneous anaphylaxis. The Rac GEF activity of DOCK5 is surprisingly not required for mast cell degranulation. Instead, DOCK5 associated with Nck2 and Akt to regulate microtubule dynamics through phosphorylation and inactivation of GSK3?. When DOCK5–Nck2–Akt interactions were disrupted, microtubule formation and degranulation response were severely impaired. Our results thus identify DOCK5 as a key signaling adaptor that orchestrates remodeling of the microtubule network essential for mast cell degranulation. PMID:24913231

Ogawa, Kana; Tanaka, Yoshihiko; Uruno, Takehito; Duan, Xuefeng; Harada, Yosuke; Sanematsu, Fumiyuki; Yamamura, Kazuhiko; Terasawa, Masao; Nishikimi, Akihiko; Côté, Jean-François

2014-01-01

104

DOCK5 functions as a key signaling adaptor that links Fc?RI signals to microtubule dynamics during mast cell degranulation.  

PubMed

Mast cells play a key role in the induction of anaphylaxis, a life-threatening IgE-dependent allergic reaction, by secreting chemical mediators that are stored in secretory granules. Degranulation of mast cells is triggered by aggregation of the high-affinity IgE receptor, Fc?RI, and involves dynamic rearrangement of microtubules. Although much is known about proximal signals downstream of Fc?RI, the distal signaling events controlling microtubule dynamics remain elusive. Here we report that DOCK5, an atypical guanine nucleotide exchange factor (GEF) for Rac, is essential for mast cell degranulation. As such, we found that DOCK5-deficient mice exhibit resistance to systemic and cutaneous anaphylaxis. The Rac GEF activity of DOCK5 is surprisingly not required for mast cell degranulation. Instead, DOCK5 associated with Nck2 and Akt to regulate microtubule dynamics through phosphorylation and inactivation of GSK3?. When DOCK5-Nck2-Akt interactions were disrupted, microtubule formation and degranulation response were severely impaired. Our results thus identify DOCK5 as a key signaling adaptor that orchestrates remodeling of the microtubule network essential for mast cell degranulation. PMID:24913231

Ogawa, Kana; Tanaka, Yoshihiko; Uruno, Takehito; Duan, Xuefeng; Harada, Yosuke; Sanematsu, Fumiyuki; Yamamura, Kazuhiko; Terasawa, Masao; Nishikimi, Akihiko; Côté, Jean-François; Fukui, Yoshinori

2014-06-30

105

Influence of a mindfulness meditation-based stress reduction intervention on rates of skin clearing in patients with moderate to severe psoriasis undergoing phototherapy (UVB) and photochemotherapy (PUVA)  

Microsoft Academic Search

OBJECTIVE: This study tests the hypothesis that stress reduction methods based on mindfulness meditation can positively influence the rate at which psoriasis clears in patients undergoing phototherapy or photochemotherapy treatment.\\u000aMETHODS: Thirty-seven patients with psoriasis about to undergo ultraviolet phototherapy (UVB) or photochemotherapy (PUVA) were randomly assigned to one of two conditions: a mindfulness meditation-based stress reduction intervention guided by

Jon Kabat-Zinn; Elizabeth V. Wheeler; Timothy Light; Anne Skillings; Mark J. Scharf; Thomas G. Cropley; David W. Hosmer; Jeffrey D. Bernhard

1998-01-01

106

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

NASA Astrophysics Data System (ADS)

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.

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

2003-10-01

107

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

PubMed

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. PMID:20102206

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

2010-02-24

108

In vivo tracking of platelets: circulating degranulated platelets rapidly lose surface P-selectin but continue to circulate and function.  

PubMed Central

To examine the hypothesis that surface P-selectin-positive (degranulated) platelets are rapidly cleared from the circulation, we developed novel methods for tracking of platelets and measurement of platelet function in vivo. Washed platelets prepared from nonhuman primates (baboons) were labeled with PKH2 (a lipophilic fluorescent dye), thrombin-activated, washed, and reinfused into the same baboons. Three-color whole blood flow cytometry was used to simultaneously (i) identify platelets with a mAb directed against glycoprotein (GP)IIb-IIIa (integrin alpha 11b beta 3), (ii) distinguish infused platelets by their PKH2 fluorescence, and (iii) analyze platelet function with mAbs. Two hours after infusion of autologous thrombin-activated platelets (P-selectin-positive, PKH2-labeled), 95 +/- 1% (mean +/- SEM, n = 5) of the circulating PKH2-labeled platelets had become P-selectin-negative. Compared with platelets not activated with thrombin preinfusion, the recovery of these circulating PKH2-labeled, P-selectin-negative platelets was similar 24 h after infusion and only slightly less 48 h after infusion. The loss of platelet surface P-selectin was fully accounted for by a 67.1 +/- 16.7 ng/ml increase in the plasma concentration of soluble P-selectin. The circulating PKH2-labeled, P-selectin-negative platelets were still able to function in vivo, as determined by their (i) participation in platelet aggregates emerging from a bleeding time wound, (ii) binding to Dacron in an arteriovenous shunt, (iii) binding of mAb PAC1 (directed against the fibrinogen binding site on GPIIb-IIIa), and (iv) generation of procoagulant platelet-derived microparticles. In summary, (i) circulating degranulated platelets rapidly lose surface P-selectin to the plasma pool, but continue to circulate and function; and (ii) we have developed novel three-color whole blood flow cytometric methods for tracking of platelets and measurement of platelet function in vivo. Images Fig. 2 Fig. 5 PMID:8876231

Michelson, A D; Barnard, M R; Hechtman, H B; MacGregor, H; Connolly, R J; Loscalzo, J; Valeri, C R

1996-01-01

109

Britanin Suppresses IgE/Ag-Induced Mast Cell Activation by Inhibiting the Syk Pathway.  

PubMed

The aim of this study was to determine whether britanin, isolated from the flowers of Inula japonica (Inulae Flos), modulates the generation of allergic inflammatory mediators in activated mast cells. To understand the biological activity of britanin, the authors investigated its effects on the generation of prostaglandin D2 (PGD2), leukotriene C4 (LTC4), and degranulation in IgE/Ag-induced bone marrow-derived mast cells (BMMCs). Britanin dose dependently inhibited degranulation and the generations of PGD2 and LTC4 in BMMCs. Biochemical analyses of IgE/Ag-mediated signaling pathways demonstrated that britanin suppressed the phosphorylation of Syk kinase and multiple downstream signaling processes, including phospholipase C?1 (PLC?1)-mediated calcium influx, the activation of mitogen-activated protein kinases (MAPKs; extracellular signal-regulated kinase 1/2, c-Jun NH2-terminal kinase and p38), and the nuclear factor-?B (NF-?B) pathway. Taken together, the findings of this study suggest britanin suppresses degranulation and eicosanoid generation by inhibiting the Syk-dependent pathway and britanin might be useful for the treatment of allergic inflammatory diseases. PMID:25009699

Lu, Yue; Li, Xian; Park, Young Na; Kwon, Okyun; Piao, Donggen; Chang, Young-Chae; Kim, Cheorl-Ho; Lee, Eunkyung; Son, Jong Keun; Chang, Hyeun Wook

2014-05-01

110

Impaired Degranulation and Proliferative Capacity of Mycobacterium tuberculosis-Specific CD8+ T Cells in HIV-Infected Individuals With Latent Tuberculosis.  

PubMed

Human immunodeficiency virus (HIV)-infected individuals with latent Mycobacterium tuberculosis infection have substantially higher rates of progression to active tuberculosis than HIV-uninfected individuals with latent tuberculosis. To explore HIV-induced deficits in M. tuberculosis-specific CD8(+) T-cell functions, we compared interferon ? production, degranulation, and proliferation of CD8(+) T cells in response to M. tuberculosis peptides (ESAT-6/CFP-10) between HIV-infected (median CD4(+) T-cell count, 522 cells/µL; interquartile range, 318-585 cells/µL) and HIV-uninfected individuals with latent tuberculosis from South Africa. We found that M. tuberculosis-specific degranulation and proliferative capacities were impaired in the HIV-infected group. Thus, our results suggest that HIV coinfection compromises CD8(+) T-cell functions in latent tuberculosis. PMID:25205634

Kalokhe, Ameeta S; Adekambi, Toidi; Ibegbu, Chris C; Ray, Susan M; Day, Cheryl L; Rengarajan, Jyothi

2015-02-15

111

Impact of Actin Rearrangement and Degranulation on the Membrane Structure of Primary Mast Cells: A Combined Atomic Force and Laser Scanning Confocal Microscopy Investigation  

PubMed Central

Degranulation of bone marrow-derived mast cells (BMMCs) triggered by antigens (e.g., 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) and secretagogues (e.g., poly-L-lysine) was investigated by combined atomic force microscopy (AFM) and laser scanning confocal microscopy (LSCM). This combination enables the simultaneous visualization and correlation of membrane morphology with cytoskeletal actin arrangement and intracellular granules. Two degranulation mechanisms and detailed membrane structures that directly corresponded to the two stimuli were revealed. In DNP-BSA triggered activation, characteristic membrane ridges formed in accordance with the rearrangement of underlying F-actin networks. Individual granules were visualized after they released their contents, indicating a “kiss-and-run” pathway. In BMMCs stimulated by poly-L-lysine, lamellopodia and filopodia were observed in association with the F-actin assemblies at and near the cell periphery, whereas craters were observed on the central membrane lacking F-actin. These craters represent a new membrane feature resulting from the “kiss-and-merge” granule fusion. This work provides what we believe is important new insight into the local membrane structures in correlation with the cytoskeleton arrangement and detailed degranulation processes. PMID:19217878

Deng, Zhao; Zink, Tiffany; Chen, Huan-yuan; Walters, Deron; Liu, Fu-tong; Liu, Gang-yu

2009-01-01

112

I?B kinase 2 is essential for IgE-induced mast cell de novo cytokine production but not for degranulation.  

PubMed

The immunoglobulin E (IgE)-mediated mast cell (MC) response is central to the pathogenesis of type I allergy and asthma. I?B kinase 2 (IKK2) was reported to couple IgE-induced signals to MC degranulation by phosphorylating the SNARE protein SNAP23. We investigated MC responses in mice with MC-specific inactivation of IKK2 or NF-?B essential modulator (NEMO), or animals with MC-specific expression of a mutant, constitutively active IKK2. We show that the IgE-induced late-phase cytokine response is reduced in mice lacking IKK2 or NEMO in MCs. However, anaphylactic in vivo responses of these animals are not different from those of control mice, and in vitro IKK2-deficient MCs readily phosphorylate SNAP23 and degranulate similarly to control cells in response to allergen or calcium ionophore. Constitutive overactivation of the NF-?B pathway has only slight effects on allergen-triggered MC responses. Thus, IKK2 is dispensable for MC degranulation, and the important question how IgE-induced signals trigger MC vesicle fusion remains open. PMID:25176657

Peschke, Katrin; Weitzmann, Anke; Heger, Klaus; Behrendt, Rayk; Schubert, Nadja; Scholten, Julia; Voehringer, David; Hartmann, Karin; Dudeck, Anne; Schmidt-Supprian, Marc; Roers, Axel

2014-09-11

113

Impact of actin rearrangement and degranulation on the membrane structure of primary mast cells: a combined atomic force and laser scanning confocal microscopy investigation.  

PubMed

Degranulation of bone marrow-derived mast cells (BMMCs) triggered by antigens (e.g., 2,4-dinitrophenylated bovine serum albumin (DNP-BSA) and secretagogues (e.g., poly-L-lysine) was investigated by combined atomic force microscopy (AFM) and laser scanning confocal microscopy (LSCM). This combination enables the simultaneous visualization and correlation of membrane morphology with cytoskeletal actin arrangement and intracellular granules. Two degranulation mechanisms and detailed membrane structures that directly corresponded to the two stimuli were revealed. In DNP-BSA triggered activation, characteristic membrane ridges formed in accordance with the rearrangement of underlying F-actin networks. Individual granules were visualized after they released their contents, indicating a "kiss-and-run" pathway. In BMMCs stimulated by poly-L-lysine, lamellopodia and filopodia were observed in association with the F-actin assemblies at and near the cell periphery, whereas craters were observed on the central membrane lacking F-actin. These craters represent a new membrane feature resulting from the "kiss-and-merge" granule fusion. This work provides what we believe is important new insight into the local membrane structures in correlation with the cytoskeleton arrangement and detailed degranulation processes. PMID:19217878

Deng, Zhao; Zink, Tiffany; Chen, Huan-yuan; Walters, Deron; Liu, Fu-tong; Liu, Gang-yu

2009-02-18

114

Platelet degranulation and glycoprotein IIbIIIa opening are not related to bleeding phenotype in severe haemophilia A patients.  

PubMed

Recently we reported data suggesting that platelets could compensate for the bleeding phenotype in severe haemophilia A (HA). The aim of this study was to confirm these results in a larger population with a detailed characterisation of clinical phenotype. Patients with diagnostic severe HA (FVIII:C <1%) were scored for clinical phenotype by integrating data on age at first joint bleed, joint damage, bleeding frequency and FVIII consumption. Phenotype was defined as onset of joint bleeding-score + arthropathy-score + joint bleeding-score + (2* treatment intensity-score). After a washout period of three days, blood was collected for measurement of basal level of platelet activation, platelet reactivity, endothelial cell activation and presence of procoagulant phospholipids in plasma. Thirty-three patients with severe HA were included, 13 patients with a mild, 12 patients with an average and eight patients with a severe clinical phenotype. No relevant differences in basal level of platelet activation, platelet reactivity, endothelial cell activation and procoagulant phospholipids between all three groups were observed. The mean annual FVIII consumption per kg did not correlate with the platelet P-selectin expression and glycoprotein (GP)IIbIIIa activation on platelets. In conclusion, variability in clinical phenotype in patients with diagnostic severe HA is not related to platelet activation or reactivity, measured as platelet degranulation and platelet GPIIbIIIa opening. PMID:24477967

van Bladel, Esther R; Schutgens, Roger E G; Fischer, Kathelijn; de Groot, Philip G; Roest, Mark

2014-06-01

115

Angiopoietin1 Inhibits Mast Cell Activation and Protects against Anaphylaxis  

PubMed Central

Since morbidity and mortality rates of anaphylaxis diseases have been increasing year by year, how to prevent and manage these diseases effectively has become an important issue. Mast cells play a central regulatory role in allergic diseases. Angiopoietin1 (Ang-1) exhibits anti-inflammatory properties by inhibiting vascular permeability, leukocyte migration and cytokine production. However, Ang-1's function in mast cell activation and anaphylaxis diseases is unknown. The results of our study suggest that Ang-1 decreased lipopolysaccharide (LPS)-induced pro-inflammatory cytokines production of mast cells by suppressing I?B phosphorylation and NF-?B nuclear translocation. Ang-1 also strongly inhibited compound 48/80 induced and Fc?RI-mediated mast cells degranulation by decreasing intracellular calcium levels in vitro. In vivo lentivirus-mediated delivery of Ang-1 in mice exhibited alleviated leakage in IgE-dependent passive cutaneous anaphylaxis (PCA). Furthermore, exogenous Ang-1 intervention treatment prevented mice from compound 48/80-induced mesentery mast cell degranulation, attenuated increases in pro-inflammatory cytokines, relieved lung injury, and improved survival in anaphylaxis shock. The results of our study reveal, for the first time, the important role of Ang-1 in the activation of mast cells, and identify a therapeutic effect of Ang-1 on anaphylaxis diseases. PMID:24586553

Li, Meng-Tao; Liu, Yi-Nan; He, Qi-Hua; Xiao, Jun-Jun; Bai, Yun

2014-01-01

116

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

PubMed

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 ?M [confidence interval (CI): 0.1-0.9] versus 3.8 ?M (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. PMID:24917545

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

2014-08-01

117

Comparison of Mast Cells and Inflammatory Cells within Periapical Lesions and Comparison of Degranulated Mast Cells Between Fibrous and Inflamed Area in Radicular Cysts: An Immunohistochemical Study  

PubMed Central

Objective: The role of mast cells as the key effector of allergic inflammation, anaphylactic inflammatory reactions and in the pathogenesis of chronic inflammation, is well-known. The present study is adopted to compare mast cells and inflammatory cells within periapical granuloma and cysts and localize the mast cells and quantify their number in the periapical cysts so as to propose a role of mast cells in the pathogenesis of this lesion. Materials and Methods: Biopsy specimens of 30 periapical lesions were stained with hematoxylin–eosin, and immunohistochemical Mast Cell Tryptase from Bio SB (IHC detection system kit) antibody. The tryptase positive mast cells and mononuclear inflammatory cells were counted in 10 consecutive high power fields (100X) using the binocular microscope from Motic attached to a computer with Motic Advanced Images 3.2 software. Results: Comparative microscopic analysis indicated that periapical cyst shows more percentage of mast cells and less percentage of inflammatory cell than periapical granuloma (comparison of mean and standard deviation of total number of mast cells and inflammatory cells, mast cells 3.15±1.39 in the granuloma group and 4.43±1.91in the cyst group, inflammatory cells, 67.11±1.2 in the granuloma group and 52.66±0.8 in the cyst group). Numerous degranulated mast cells were observed in the fibrous wall than the inflammatory infiltrate of the periapical cysts. The mean and standard deviation of degranulated mast cells between the inflammatory and fibrous zone within the cyst group, being 0.95±1.10 and1.68±1.34 respectively. The values varied significantly between the two zones. Conclusion: The number of inflammatory cells in the cyst group is less than periapical granuloma and total number of mast cells in the cyst group is more as compared to periapical granuloma. The degranulated cells were quantified and they were higher in the fibrous area of the cysts than the inflammatory zone. This study could support the fact that the various mediators released on degranulation play a role in the connective tissue remodeling, chronicity and expansion of the periapical lesion.

Sood, Rahul; Akifuddin, Syed; Sidhu, Gagandeep Kaur; Khan, Nadia; Singla, Kapil

2014-01-01

118

Balance of apoptotic and anti-apoptotic marker and perforin granule release in squamous intraepithelial lesions. HIV infection leads to a decrease in perforin degranulation.  

PubMed

Cell-mediated cytotoxicity plays an important role in the regulation to HPV-associated cervical intraepithelial neoplasia. HIV co-infection is related to poorer prognosis and more rapid clinical progression to cancer. We evaluated the presence of cervical inflammatory cells, apoptotic (Bax, Bcl-2, FasL, NOS2, perforin) markers and the degranulating expressing cell marker (CD107a) in low and high squamous intraepithelial lesions (LSIL and HSIL, respectively) from HIV-negative and -positive women. Higher percentage of cervical CD4(+), CD8(+) T cells and macrophage were observed in LSIL and HSIL groups when compared with control, especially in epithelium and basal layer of epithelium. However, progression from LSIL to HSIL did not change the frequency of inflammatory cells. HIV-infection lead to a reduction on cervical CD4(+) T cell infiltration and an increased CD8(+) T cell distribution in LSIL groups. A balance between pro- and anti-apoptotic protein expressions was verified. Bax-expressing cells were present in all groups and were rarely expressed in keratinocytes in the epithelium in LSIL and control groups, but notably decreased in HSIL group. However, its frequency was enhanced in the basal layer of the epithelium meanly in LSIL group. Bcl2-expressing cells in the epithelium and the stroma were enhanced in HSIL group when compared with LSIL group. HIV-infection did not interfere in both expressions NOS2 expression was located on keratinocytes in both LSIL and HSIL groups when compared with control group. There were few FasL cervical expressing cells in all groups. Indeed, perforin was identified in few cervical cells. However, CD107a, a surface marker for cellular degranulation was significantly higher in epithelium, basal layer of epithelium and stroma in LSIL and HSIL, respectively, when compared with control group. These results support that HIV infection may induce reduction on inflammatory cervical cell degranulation corroborating to carcinogenesis process. This is the first description on the role of HIV in downregulation of perforin degranulation in the cervical lesions and it might be related to carcinogenesis. PMID:23791892

Fernandes, Ana Teresa G; da Rocha, Natalia Pereira; Avvad, Elyzabeth; Grinsztejn, Beatriz J; Russomano, Fabio; Tristão, Aparecida; Quintana, Marcel de Souza Borges; Perez, Mauricio A; Conceição-Silva, Fátima; Bonecini-Almeida, Maria da Gloria

2013-10-01

119

Differential effects of IL-21 and IL-15 on perforin expression, lysosomal degranulation, and proliferation in CD8 T cells of patients with human immunodeficiency virus-1 (HIV)  

PubMed Central

An urgent need exists to devise strategies to augment antiviral immune responses in patients with HIV who are virologically well controlled and immunologically stable on highly active antiretroviral therapy (HAART). The objective of this study was to compare the immunomodulatory effects of the cytokines interleukin (IL)–21 with IL-15 on CD8 T cells in patients with HIV RNA of less than 50 copies/mL and CD4 counts greater than 200 cells/mm.3 Patient CD8 T cells displayed skewed maturation and decreased perforin expression compared with healthy controls. Culture of freshly isolated patient peripheral-blood mononuclear cells (PBMCs) for 5 hours to 5 days with IL-21 resulted in up-regulation of perforin in CD8 T cells, including memory and effector subsets and virus-specific T cells. IL-21 did not induce T-cell activation or proliferation, nor did it augment T-cell receptor (TCR)–induced degranulation. Treatment of patient PBMCs with IL-15 resulted in induction of perforin in association with lymphocyte proliferation and augmentation of TCR-induced degranulation. Patient CD8 T cells were more responsive to cytokine effects than the cells of healthy volunteers. We conclude that CD8 T cells of patients with HIV can be modulated by IL-21 to increase perforin expression without undergoing overt cellular activation. IL-21 could potentially be useful for its perforin-enhancing properties in anti-HIV immunotherapy. PMID:17192392

White, Lesley; Krishnan, Subramaniam; Strbo, Natasa; Liu, Huanliang; Kolber, Michael A.; Lichtenheld, Mathias G.; Pahwa, Rajendra N.

2007-01-01

120

Neisserial Porins Inhibit Human Neutrophil Actin Polymerization, Degranulation, Opsonin Receptor Expression, and Phagocytosis but Prime the Neutrophils To Increase Their Oxidative Burst  

Microsoft Academic Search

Porins are trimeric proteins that constitute water-filled pores that allow transmembrane diffusion of small solutes through the outer membrane layer of gram-negative bacteria. The porins are capable of inserting into the membranes of eucaryotic cells, and in the present study we have examined the in vitro effects on neutrophil functions of the following purified porins: meningococcal outer membrane protein classes

ROBERT BJERKNES; HILDE-KARI GUTTORMSEN; CLAUS OLA SOLBERG; ANDLEE M. WETZLER

121

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

PubMed

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 17?-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-?1 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-?1, 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. PMID:25403608

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

2015-02-01

122

Mountain cedar pollen induces IgE-independent mast cell degranulation, IL-4 production, and intracellular reactive oxygen species generation  

PubMed Central

Cedar pollens cause severe allergic disease throughout the world. We have previously characterized allergenic pollen glycoproteins from mountain cedar (Juniperus ashei) that bind to allergen-specific immunoglobulin E (IgE). In the present report, we investigated an alternative pathway of mast cell activation by mountain cedar pollen extract through IgE-independent mechanisms. We show that mountain cedar pollen directly induces mast cell serotonin and IL-4 release and enhances release induced by IgE cross-linking. Concomitant with mediator release, high levels of intracellular reactive oxygen species (ROS) were generated, and both ROS and serotonin release were inhibited by anti-oxidants. These findings suggest that alternative mechanisms exist whereby pollen exposure enhances allergic inflammatory mediator release through mechanisms that involve ROS. These mechanisms have the potential for enhancing the allergenic potency of pollens. PMID:21944563

Endo, Shuichiro; Hochman, Daniel J.; Midoro-Horiuti, Terumi; Goldblum, Randall M.; Brooks, Edward G.

2011-01-01

123

In-Cell Intrabody Selection from a Diverse Human Library Identifies C12orf4 Protein as a New Player in Rodent Mast Cell Degranulation  

PubMed Central

The high specificity of antibodies for their antigen allows a fine discrimination of target conformations and post-translational modifications, making antibodies the first choice tool to interrogate the proteome. We describe here an approach based on a large-scale intracellular expression and selection of antibody fragments in eukaryotic cells, so-called intrabodies, and the subsequent identification of their natural target within living cell. Starting from a phenotypic trait, this integrated system allows the identification of new therapeutic targets together with their companion inhibitory intrabody. We applied this system in a model of allergy and inflammation. We first cloned a large and highly diverse intrabody library both in a plasmid and a retroviral eukaryotic expression vector. After transfection in the RBL-2H3 rat basophilic leukemia cell line, we performed seven rounds of selection to isolate cells displaying a defect in Fc?RI-induced degranulation. We used high throughput sequencing to identify intrabody sequences enriched during the course of selection. Only one intrabody was common to both plasmid and retroviral selections, and was used to capture and identify its target from cell extracts. Mass spectrometry analysis identified protein RGD1311164 (C12orf4), with no previously described function. Our data demonstrate that RGD1311164 is a cytoplasmic protein implicated in the early signaling events following Fc?RI-induced cell activation. This work illustrates the strength of the intrabody-based in-cell selection, which allowed the identification of a new player in mast cell activation together with its specific inhibitor intrabody. PMID:25122211

Bec, Nicole; Parez, Vincent; Hahn, Chang S.; Mollevi, Caroline; Parrinello, Hugues; Desvignes, Jean-Pierre; Larroque, Christian; Jupp, Ray; Dariavach, Piona; Martineau, Pierre

2014-01-01

124

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

PubMed

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 Fc? receptors (Fc?RI) 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 Fc?RI 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 Fc?RI accumulation in low-density membrane fragments, i.e., lipid rafts, which may facilitate Fc?RI 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. PMID:23861175

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

2013-09-01

125

Kalanchoe pinnata inhibits mast cell activation and prevents allergic airway disease.  

PubMed

Aqueous extract of Kalanchoe pinnata (Kp) have been found effective in models to reduce acute anaphylactic reactions. In the present study, we investigate the effect of Kp and the flavonoid quercetin (QE) and quercitrin (QI) on mast cell activation in vitro and in a model of allergic airway disease in vivo. Treatment with Kp and QE in vitro inhibited degranulation and cytokine production of bone marrow-derived mast cells following IgE/Fc?RI crosslinking, whereas treatment with QI had no effect. Similarly, in vivo treatment with Kp and QE decreased development of airway hyperresponsiveness, airway inflammation, goblet cell metaplasia and production of IL-5, IL-13 and TNF. In contrast, treatment with QI had no effect on these parameters. These findings demonstrate that treatment with Kp or QE is effective in treatment of allergic airway disease, providing new insights to the immunomodulatory functions of this plant. PMID:21802918

Cruz, E A; Reuter, S; Martin, H; Dehzad, N; Muzitano, M F; Costa, S S; Rossi-Bergmann, B; Buhl, R; Stassen, M; Taube, C

2012-01-15

126

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

PubMed Central

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

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

2014-01-01

127

Piperine inhibits type II phosphatidylinositol 4-kinases: a key component in phosphoinositides turnover.  

PubMed

Piperine has been shown to have anti-inflammatory properties. The molecular mechanisms by which it mediates anti-inflammatory activities remain elusive. Type II phosphatidylinositol 4-kinase(s) are key components in Fc?RI receptor-mediated signaling leading to inflammatory mediators release in RBL-2H3 cells. The effects of piperine on IgE-mediated signaling and mast cell degranulation were investigated. Pretreatment of RBL-2H3 cells with piperine inhibited IgE-induced activation of type II PtdIns 4-kinase(s). In vitro lipid kinase assays showed piperine-inhibited type II PtdIns 4-kinase activity in a dose-dependent fashion with no effect on PtdIns 3-kinase activity. Concomitantly, pretreatment of RBL-2H3 cells with piperine also inhibited IgE-induced ?-hexosaminidase release in RBL-2H3 cells. These results suggest that type II PtdIns 4-kinases are part of piperine-mediated anti-inflammatory signaling mechanisms. PMID:24671493

Bojjireddy, Naveen; Sinha, Ranjeet Kumar; Subrahmanyam, Gosukonda

2014-08-01

128

Inhibition of leukocyte functions by the alkaloid isaindigotone from Isatis indigotica and some new synthetic derivatives.  

PubMed

The alkaloid isaindigotone (1a) and seven derivatives have been synthesized to study their influence on several leukocyte functions and the generation of inflammatory mediators. Isaindigotone (1a) was found to be a scavenger of superoxide generated either by the hypoxanthine/xanthine oxidase system or stimulated human neutrophils. Isaindigotone (1a) and its acetylated derivative (1b) also inhibited 5-lipoxygenase activity and leukotriene B(4) production in these cells, whereas none of the compounds affected degranulation. In RAW 264.7 macrophages stimulated with lipopolysaccharide, synthetic derivatives exerted higher inhibitory effects on prostaglandin E(2) (PGE(2)) and nitric oxide (NO) generation when compared with (1a). The presence of an acetoxyl group at C-4' favors the inhibition of NO and PGE(2) production, whereas the fluoro substituent at C-4' or the absence of substituents on the aromatic ring of the benzylidene unit improves the inhibition of PGE(2). Thus, this series of compounds can attenuate the production of mediators relevant to the inflammatory response. PMID:11678654

Molina, P; Tárraga, A; Gonzalez-Tejero, A; Rioja, I; Ubeda, A; Terencio, M C; Alcaraz, M J

2001-10-01

129

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)

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.

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

2002-07-01

130

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

PubMed

Whisky is matured in oak casks. Many nonvolatile substances (whisky congeners, WC) seep from the oak cask during the maturing process. In this study, three antiallergic agents (syringaldehyde, SA; lyoniresinol, Lyo; and ellagic acid, EA) were isolated from WC. Treatment with SA, Lyo, and EA reduced the elevation of intracellular free Ca(2+) concentration ([Ca(2+)]i) and intracellular ROS production caused by FcepsilonRI activation. The inhibitions of the elevation of [Ca(2+)]i and intracellular ROS production by SA and Lyo were mainly due to the suppression of the NADPH oxidase activity and scavenging of the produced radical, respectively. On the other hand, EA inactivated spleen tyrosine kinase and led to the inhibition of the elevation of [Ca(2+)]i and intracellular ROS production. Furthermore, it was found that WC strongly inhibited IgE binding to the FcepsilonRIalpha chain, whereas SA, Lyo, and EA did not indicate this inhibitory effect. These results suggest that WC inhibits allergic reactions through multiple mechanisms. To disclose the in vivo effects of WC, SA, Lyo, and EA, these compounds were administered to type I allergic model mice, and the passive cutaneous anaphylaxis (PCA) reaction was measured. These compounds remarkably suppressed the PCA reaction. Taken together, these findings suggest that WC seemed to be beneficial to ameliorate allergic reactions. PMID:20507065

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

2010-06-23

131

Nobiletin and tangeretin ameliorate scratching behavior in mice by inhibiting the action of histamine and the activation of NF-?B, AP-1 and p38.  

PubMed

Nobiletin and tangeretin are polymethoxy flavonoids that are abundantly present in the pericarp of Citrus unshiu (family Rutaceae) and the fruit of Citrus depressa (family Rutaceae). They exhibit various biological activities, including anti-inflammatory and anti-asthmatic effects. To evaluate the anti-allergic effects of nobiletin and tangeretin, we measured their inhibitory effects in histamine- or compound 48/80-induced scratching behavioral mice. Nobiletin and tangeretin potently inhibited scratching behavior, as well as histamine-induced vascular permeability. Furthermore, they inhibited the expression of the allergic cytokines, IL-4 and TNF-? as well as the activation of their transcription factors NF-?B, AP-1 and p38 in histamine-stimulated skin tissues. They also inhibited the expression of IL-4 and TNF-? and the activation of NF-?B and c-jun in PMA-stimulated RBL-2H3 cells. Furthermore, nobiletin and tangeretin inhibited protein kinase C (PKC) activity and the IgE-induced degranulation of RBL-2H3 cells. These agents showed potent anti-histamine effect through the Magnus test when guinea pig ileum was used. Based on these results, nobiletin and tangeretin may ameliorate scratching behavioral reactions by inhibiting the action of histamine as well as the activation of the transcription factors NF-?B and AP-1 via PKC. PMID:23938254

Jang, Se-Eun; Ryu, Kwon-Ryeol; Park, Sung-Hwan; Chung, Suna; Teruya, Yuto; Han, Myung Joo; Woo, Je-Tae; Kim, Dong-Hyun

2013-11-01

132

Inhibition of ultraviolet-induced formation of reactive oxygen species, lipid peroxidation, erythema and skin photosensitization by polypodium leucotomos.  

PubMed

The acute reactions of human skin to solar ultraviolet radiation (290-400 nm) are recognized as a form of inflammation reactions that are mediated by several possible mechanisms including (a) direct action of photons on DNA, (b) generation of reactive free radicals and reactive oxygen species involving the formation of O2.-, 1O2, H2O2, OH, etc., (c) generation of prostaglandins (PGD2, PGE2, etc.), histamine, leucotrienes, and other inflammatory mediators. It is conceivable that UV-induced reactions represent oxidative stress mediated by the formation of free radicals, reactive oxygen, lipid peroxidation, liberation of membrane phospholipids, and subsequent formation of prostaglandins by cyclo-oxygenase pathway. In this study, we examined the role of reactive oxygen species and lipid peroxidation in in vitro reactions as well as in vivo skin inflammation reactions induced by (a) UVB radiation (290-320 nm), and (b) skin photosensitization reaction by PUVA treatment involving 8-methoxypsoralen and UVA (320-400 nm) radiation and presented data for the generation of superoxide anion O2.-) and lipid peroxides. We have also evaluated, both in vitro as well as in vivo systems, the quenching or the inhibition of O2.- by a plant extract known as Polypodium leucotomos. The P. leucotomos extract was found to exhibit interesting antioxidant and anti-inflammatory as well as photoprotective properties against photo-oxidative stress involving the generation of reactive oxygen, lipid peroxidation under in vitro reactions as well as in vivo experimental conditions. Significant inhibition of UVB-induced erythemal response, and 8-methoxypsoralen plus UVA-induced phototoxic reaction after topical application or oral administration of the photosensitizer could be demonstrated in guinea pig skin and human skin following the topical application of P. leucotomos extract. The photoprotective mechanism of P.leucotomos involving interaction with reactive oxygen species or free radicals appears to have potential clinical usefulness in preventing sunburn and inhibiting phototoxic reaction. PMID:8897589

González, S; Pathak, M A

1996-04-01

133

Monomethyl fumarate augments NK cell lysis of tumor cells through degranulation and the upregulation of NKp46 and CD107a.  

PubMed

Dimethyl fumarate (DMF) is a new drug used to treat multiple sclerosis (MS) patients. Here, we examined the effects of DMF and the DMF metabolite monomethyl fumarate (MMF) on various activities of natural killer (NK) cells. We demonstrated that MMF augments the primary CD56(+), but not CD56(-), NK cell lysis of K562 and RAJI tumor cells. MMF induced NKp46 expression on the surface of CD56(+), but not CD56(-), NK cells after incubation for 24 h. This effect was closely correlated with the upregulation of CD107a expression on the surface of CD56(+) NK cells and the induction of Granzyme B release from these cells through this metabolite. An anti-NKp46 antibody inhibited the MMF-induced upregulation of CD107a and the lysis of tumor cells through CD56(+) NK cells. Thus, these results are the first to show that MMF augments CD56(+) NK cell lysis of tumor target cells, an effect mediated through NKp46. This novel effect suggests the use of MMF for therapeutic and/or preventive protocols in cancer.Cellular & Molecular Immunology advance online publication, 1 December 2014; doi:10.1038/cmi.2014.114. PMID:25435072

Vego, Heidi; Sand, Kristin L; Høglund, Rune A; Fallang, Lars-Egil; Gundersen, Glenn; Holmøy, Trygve; Maghazachi, Azzam A

2014-12-01

134

Natural Killer Cells in Perinatally HIV-1-Infected Children Exhibit Less Degranulation Compared to HIV-1-Exposed Uninfected Children and Their Expression of KIR2DL3, NKG2C, and NKp46 Correlates with Disease Severity1  

PubMed Central

NK cells play an integral role in the innate immune response by targeting virally infected and transformed cells with direct killing and providing help to adaptive responses through cytokine secretion. Whereas recent studies have focused on NK cells in HIV-1-infected adults, the role of NK cells in perinatally HIV-1-infected children is less studied. Using multiparametric flow cytometric analysis, we assessed the number, phenotype, and function of NK cell subsets in the peripheral blood of perinatally HIV-1-infected children on highly active antiretroviral therapy and compared them to perinatally exposed but uninfected children. We observed an increased frequency of NK cells expressing inhibitory killer Ig-like receptors in infected children. This difference existed despite comparable levels of total NK cells and NK cell subpopulations between the two groups. Additionally, NK cell subsets from infected children expressed, with and without stimulation, significantly lower levels of the degranulation marker CD107, which correlates with NK cell cytotoxicity. Lastly, increased expression of KIR2DL3, NKG2C, and NKp46 on NK cells correlated with decreased CD4+ T-lymphocyte percentage, an indicator of disease severity in HIV-1-infected children. Taken together, these results show that HIV-1-infected children retain a large population of cytotoxically dysfunctional NK cells relative to perinatally exposed uninfected children. This reduced function appears concurrently with distinct NK cell surface receptor expression and is associated with a loss of CD4+ T cells. This finding suggests that NK cells may have an important role in HIV-1 disease pathogenesis in HIV-1-infected children. PMID:17709553

Ballan, Wassim M.; Vu, Bien-Aimee N.; Long, Brian R.; Loo, Christopher P.; Michaëlsson, Jakob; Barbour, Jason D.; Lanier, Lewis L.; Wiznia, Andrew A.; Abadi, Jacobo; Fennelly, Glenn J.; Rosenberg, Michael G.; Nixon, Douglas F.

2014-01-01

135

Inhibiting eukaryotic transcription  

PubMed Central

This review first discusses ways in which we can evaluate transcription inhibition, describe changes in nuclear structure due to transcription inhibition, and report on genes that are paradoxically stimulated by transcription inhibition. Next, it summarizes the characteristics and mechanisms of commonly used inhibitors: ?-amanitin is highly selective for RNAP II and RNAP III but its action is slow, actinomycin D is fast but its selectivity is poor, CDK9 inhibitors such as DRB and flavopiridol are fast and reversible but many genes escape transcription inhibition. New compounds, such as triptolide, are fast and selective and able to completely arrest transcription by triggering rapid degradation of RNAP II. PMID:21922053

2011-01-01

136

Inhibition of carrageenin-induced rat paw oedema by crotapotin, a polypeptide complexed with phospholipase A2.  

PubMed Central

1. The effect of purified crotapotin, a non-toxic non-enzymatic chaperon protein normally complexed to a phospholipase A2 (PLA2) in South America rattlesnake venom, was studied in the acute inflammatory response induced by carrageenin (1 mg/paw), compound 48/80 (3 micrograms/paw) and 5-hydroxytryptamine (5-HT) (3 micrograms/paw) in the rat hind-paw. The effects of crotapotin on platelet aggregation, mast cell degranulation and eicosanoid release from guinea-pig isolated lung were also investigated. 2. Subplantar co-injection of crotapotin (1 and 10 micrograms/paw) with carrageenin or injection of crotapotin (10 micrograms/paw) into the contralateral paw significantly inhibited the carrageenin-induced oedema. This inhibition was also observed when crotapotin (10-30 micrograms/paw) was administered either intraperitoneally or orally. Subplantar injection of heated crotapotin (15 min at 60 degrees C) failed to inhibit carrageenin-induced oedema. Subplantar injection of crotapotin (10 micrograms/paw) also significantly inhibited the rat paw oedema induced by compound 48/80, but it did not affect 5-HT-induced oedema. 3. In adrenalectomized animals, subplantar injection of crotapotin markedly inhibited the oedema induced by carrageenin. The inhibitory effect of crotapotin was also observed in rats depleted of histamine and 5-HT stores. 4. Crotapotin (30 micrograms/paw) had no effect on either the histamine release induced by compound 48/80 in vitro or on the platelet aggregation induced by both arachidonic acid (1 nM) and platelet activating factor (1 microM) in human platelet-rich plasma. The platelet aggregation and thromboxane B2 (TXB2) release induced by thrombin (100 mu ml-1) in washed human platelets were also not affected by crotapotin.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7537590

Landucci, E C; Antunes, E; Donato, J L; Faro, R; Hyslop, S; Marangoni, S; Oliveira, B; Cirino, G; de Nucci, G

1995-01-01

137

Inhibition of platelet functions by a monoclonal antibody (LYP20) directed against a granule membrane glycoprotein (GMP-140/PADGEM).  

PubMed

Granule membrane protein (GMP-140), also known as platelet activation-dependent granule-external membrane (PAD-GEM) is an integral membrane glycoprotein that is expressed on the platelet surface following degranulation. GMP-140, also expressed by endothelial cells, is part of a new family of cell adhesion molecules (selectins) related to the endothelial leukocyte adhesion molecule (ELAM-1) and to the lymphocyte homing receptors in humans (Leu-8/TQ1) and in mouse (gp90MEL-14). The role of GMP-140 in platelet functions remains to be elucidated. In this study, a monoclonal antibody, LYP20, was raised against GMP-140. LYP20, directed against a disulphide bridge-dependent epitope, significantly binds to thrombin-stimulated platelets (12,200 +/- 1,184 bound molecules/platelet, kd = 5.0 +/- 0.61 nmol/L) compared with controls (2,400 +/- 266 molecules/platelet, kd = 2.3 +/- 0.54 nmol/L) and inhibits collagen or thrombin-induced aggregation of washed platelets or platelets in platelet-rich plasma. In addition, LYP20 inhibits rosetting of thrombin-activated platelets to U937 cells. These results strongly suggest that GMP-140 plays an important role in platelet aggregation and platelet interaction with other blood cells. PMID:2015399

Parmentier, S; McGregor, L; Catimel, B; Leung, L L; McGregor, J L

1991-04-15

138

Histamine H4-receptors inhibit mast cell renin release in ischemia/reperfusion via protein kinase C ?-dependent aldehyde dehydrogenase type-2 activation.  

PubMed

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 G?i/o-coupled, might activate a protein kinase C isotype-? (PKC?)-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 PKC? 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 PKC? 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

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

2014-06-01

139

Nadroparine inhibits the hypersensitivity response in the conjunctiva  

Microsoft Academic Search

This study sought to investigate the effects of nadroparine on an in vivo experimental model of type I hypersensitivity response in the rat conjunctiva. Following drug application onto the eye, either before or after challenge with the mast cell degranulator, basic polyamine compound 48\\/80, the conjunctival histamine content and the nitrite levels in the conjunctival lavage fluid were quantified fluorometrically

Vassiliki Giannoulaki; Miltiades Papathanassiou; Nikolaos M. Sitaras; Ekaterini Tiligada

2003-01-01

140

Inhibition of selectin binding  

DOEpatents

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.

Nagy, Jon O. (Rodeo, CA); Spevak, Wayne R. (Albany, CA); Dasgupta, Falguni (New Delhi, IN); Bertozzi, Caroline (Albany, CA)

2001-10-09

141

Inhibition of selectin binding  

DOEpatents

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.

Nagy, Jon O. (Rodeo, CA); Spevak, Wayne R. (Albany, CA); Dasgupta, Falguni (New Delhi, IN); Bertozzi, Caroline (Albany, CA)

1999-01-01

142

Inhibition of selectin binding  

DOEpatents

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.

Nagy, Jon O. (Rodeo, CA); Spevak, Wayne R. (Albany, CA); Dasgupta, Falguni (New Delhi, IN); Bertozzi, Carolyn (Albany, CA)

1999-10-05

143

AOP description: Acetylcholinesterase inhibition  

EPA Science Inventory

This adverse outcome pathway (AOP) leverages existing knowledge in the open literature to describe the linkage between inhibition of acetylcholinesterase (AChE) and the subsequent mortality resulting from impacts at cholinergic receptors. The AOP takes a chemical category approa...

144

Psychotherapy by reciprocal inhibition  

Microsoft Academic Search

Reciprocal inhibition is a process of relearning whereby in the presence of a stimulus a non-anxiety-producing response is\\u000a continually repeated until it extinguishes the old, undesirable response. A variety of the techniques based on reciprocal\\u000a inhibition, such as systematic desensitization, avoidance conditioning, and the use of assertion, are described in detail.\\u000a Behavior therapy techniques evaluated on the basis of their

Joseph Wolpe

1968-01-01

145

Chitin deacetylase product inhibition.  

PubMed

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. PMID:21298809

Jaworska, Malgorzata M

2011-02-01

146

Selinidin suppresses IgE-mediated mast cell activation by inhibiting multiple steps of Fc epsilonRI signaling.  

PubMed

IgE-mediated mast cell activation is critical for development of allergic inflammation. We have recently found that selinidin, one of the coumarin derivatives isolated from Angelica keiskei, attenuates mast cell degranulation following engagement of the high-affinity receptor for IgE (Fc epsilonRI) with IgE and antigen. In the present study, we investigated the effects of selinidin on intracellular signaling and mast cell activation employing bone marrow-derived mast cells. Here, we report that selinidin attenuates the release of beta-hexosaminidase, synthesis of leukotriene C4, and production of tumor necrosis factor-alpha without affecting IgE-Fc epsilonRI binding. Furthermore, biochemical analyses of the Fc epsilonRI-mediated signaling pathway demonstrated that selinidin decreases phosphorylation of phospholipase C-gamma1, p38 mitogen-activated protein kinase, and IkappaB-alpha upon FcepsilonRI stimulation. These results suggest that this compound suppresses IgE-mediated mast cell activation by inhibiting multiple steps of FcepsilonRI-dependent signaling pathways and would be beneficial for the prevention of allergic inflammation. PMID:18310907

Kishiro, Sachiko; Nunomura, Satoshi; Nagai, Hisashi; Akihisa, Toshihiro; Ra, Chisei

2008-03-01

147

Inhibition of the IgE-Mediated Activation of RBL-2H3 Cells by TIPP, a Novel Thymic Immunosuppressive Pentapeptide  

PubMed Central

TIPP is a novel thymic immunosuppressive pentapeptide originally obtained from calf thymic immunosuppressive extract. The present study aimed to investigate the inhibitory activity of TIPP on IgE-mediated activation of RBL-2H3 cells. Release of ?-hexosaminidase and histamine, intracellular calcium, membrane ruffling, mRNA levels of cytokines, cyclooxygenase-2 (COX-2) expression, and activation of mitogen-activated protein kinases (MAP kinases) and NF-?B were determined by colorimetric assay, fluorescence spectrophotometer, confocal fluorescence microscope, quantification PCR, and Western blot, respectively. The results showed that TIPP significantly inhibited the degranulation in IgE-antigen complex-stimulated RBL-2H3 cells without cytotoxicity. TIPP significantly suppressed the increase of intracellular calcium and the rearrangement of F-actin, attenuated the transcription of pro-inflammatory cytokines (IL-3, -4, -6, -13, TNF-?, and monocyte chemotactic protein-1 (MCP-1)), and decreased the expression of COX-2. Western blot analysis showed that TIPP had an inhibitory activity on the phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and ERK kinase 1/2 (MEK1/2), and inhibited the activation of NF-?B. The data suggested that TIPP effectively suppressed IgE-mediated activation of RBL-2H3 cells via blocking MEK/ERK and NF-?B signaling pathways. PMID:25608657

Lian, Qianqian; Cheng, Yanna; Zhong, Chuanqing; Wang, Fengshan

2015-01-01

148

Inhibition of the IgE-Mediated Activation of RBL-2H3 Cells by TIPP, a Novel Thymic Immunosuppressive Pentapeptide.  

PubMed

TIPP is a novel thymic immunosuppressive pentapeptide originally obtained from calf thymic immunosuppressive extract. The present study aimed to investigate the inhibitory activity of TIPP on IgE-mediated activation of RBL-2H3 cells. Release of ?-hexosaminidase and histamine, intracellular calcium, membrane ruffling, mRNA levels of cytokines, cyclooxygenase-2 (COX-2) expression, and activation of mitogen-activated protein kinases (MAP kinases) and NF-?B were determined by colorimetric assay, fluorescence spectrophotometer, confocal fluorescence microscope, quantification PCR, and Western blot, respectively. The results showed that TIPP significantly inhibited the degranulation in IgE-antigen complex-stimulated RBL-2H3 cells without cytotoxicity. TIPP significantly suppressed the increase of intracellular calcium and the rearrangement of F-actin, attenuated the transcription of pro-inflammatory cytokines (IL-3, -4, -6, -13, TNF-?, and monocyte chemotactic protein-1 (MCP-1)), and decreased the expression of COX-2. Western blot analysis showed that TIPP had an inhibitory activity on the phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK1/2) and ERK kinase 1/2 (MEK1/2), and inhibited the activation of NF-?B. The data suggested that TIPP effectively suppressed IgE-mediated activation of RBL-2H3 cells via blocking MEK/ERK and NF-?B signaling pathways. PMID:25608657

Lian, Qianqian; Cheng, Yanna; Zhong, Chuanqing; Wang, Fengshan

2015-01-01

149

The Bruton tyrosine kinase inhibitor PCI-32765 ameliorates autoimmune arthritis by inhibition of multiple effector cells  

PubMed Central

Introduction The aim was to determine the effect of the Bruton tyrosine kinase (Btk)-selective inhibitor PCI-32765, currently in Phase I/II studies in lymphoma trials, in arthritis and immune-complex (IC) based animal models and describe the underlying cellular mechanisms. Methods PCI-32765 was administered in a series of murine IC disease models including collagen-induced arthritis (CIA), collagen antibody-induced arthritis (CAIA), reversed passive anaphylactic reaction (RPA), and passive cutaneous anaphylaxis (PCA). Clinical and pathologic features characteristic of each model were examined following treatment. PCI-32765 was then examined in assays using immune cells relevant to the pathogenesis of arthritis, and where Btk is thought to play a functional role. These included proliferation and calcium mobilization in B cells, cytokine and chemokine production in monocytes/macrophages, degranulation of mast cells and its subsequent cytokine/chemokine production. Results PCI-32765 dose-dependently and potently reversed arthritic inflammation in a therapeutic CIA model with an ED50 of 2.6 mg/kg/day. PCI-32765 also prevented clinical arthritis in CAIA models. In both models, infiltration of monocytes and macrophages into the synovium was completely inhibited and importantly, the bone and cartilage integrity of the joints were preserved. PCI-32765 reduced inflammation in the Arthus and PCA assays. In vitro, PCI-32765 inhibited BCR-activated primary B cell proliferation (IC50 = 8 nM). Following Fc?R stimulation, PCI-32765 inhibited TNF?, IL-1? and IL-6 production in primary monocytes (IC50 = 2.6, 0.5, 3.9 nM, respectively). Following Fc?RI stimulation of cultured human mast cells, PCI-32765 inhibited release of histamine, PGD2, TNF-?, IL-8 and MCP-1. Conclusions PCI-32765 is efficacious in CIA, and in IC models that do not depend upon autoantibody production from B cells. Thus PCI-32765 targets not only B lymphocytes but also monocytes, macrophages and mast cells, which are important Btk-expressing effector cells in arthritis. PMID:21752263

2011-01-01

150

Semantic processing and response inhibition.  

PubMed

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. PMID:24025798

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

151

Latent inhibition in schizophrenia  

Microsoft Academic Search

Latent inhibition (LI) refers to the retarded acquisition of a conditioned response that occurs if the subject being tested is first preexposed to the to-be-conditioned stimulus (CS) without the paired unconditioned stimulus (UCS). Because the ‘irrelevance’ of the to-be-conditioned stimulus is established during non-contingent preexposure, the slowed acquisition of the CS-UCS association is thought to reflect the process of overcoming

Neal R. Swerdlow; David L. Braff; Heidi Hartston; William Perry; Mark A. Geyer

1996-01-01

152

PKC?II inhibition attenuates myocardial infarction induced heart failure and is associated with a reduction of fibrosis and pro-inflammatory responses  

PubMed Central

Protein kinase C ?II (PKC?II) levels increase in the myocardium of patients with end-stage heart failure (HF). Also targeted over-expression of PKC?II in the myocardium of mice leads to dilated cardiomyopathy associated with inflammation, fibrosis and myocardial dysfunction. These reports suggest a deleterious role of PKC?II in HF development. Using a post-myocardial infarction (MI) model of heart failure in rats, we determined the benefit of chronic inhibition of PKC?II on the progression of heart failure over a period of 6 weeks after the onset of symptoms and the cellular basis for these effects. Four weeks after MI, rats with HF signs that were treated for 6 weeks with the PKC?II selective inhibitor (?IIV5-3 conjugated to TAT47-57 alone) (3mg/kg/day) showed improved fractional shortening (from 21% to 35%) compared to control (TAT47-57 alone). Formalin-fixed mid-ventricle tissue sections stained with picrosirius red, hematoxylin-eosin and toluidine blue dyes exhibited a 150% decrease in collagen deposition, a two-fold decrease in inflammation and a 30% reduction in mast cell degranulation, respectively, in rat hearts treated with the selective PKC?II inhibitor. Further, a 90% decrease in active TGF?1 and a significant reduction in SMAD2/3 phosphorylation indicated that the selective inhibition of PKC?II attenuates cardiac remodeling mediated by the TGF-SMAD signaling pathway. Therefore, sustained selective inhibition of PKC?II in a post-MI HF rat model improves cardiac function and is associated with inhibition of pathological myocardial remodeling. PMID:20874717

Palaniyandi, Suresh Selvaraj; Ferreira, Julio Cesar Batista; Brum, Patricia Chakur; Mochly-Rosen, Daria

2011-01-01

153

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

PubMed Central

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

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

154

Inhibition of matrix metalloproteinase MMP-2 activates chloride current in human airway epithelial cells.  

PubMed

Matrix metalloproteinases (MMPs) are involved in the remodeling and degradation of the extracellular matrix. Recently, it has been found that MMPs also contribute to processes not directly related to tissue remodeling, such as platelet aggregation or degranulation of airway gland cells. Since mucus secretion is closely related to ion channel function, we investigated whether MMPs could also be involved in the regulation of ion channels. We used human airway submucosal cell line Calu-3 to study the effects of MMPs on whole-cell current and transepithelial short-circuit current (I(sc)). Phenanthroline, a specific inhibitor of MMPs, increased whole-cell current with the half-maximally effective dose of 5.2 microM, and reversibly activated I(sc) in transepithelial measurements. Current stimulated by phenanthroline displayed linear current-voltage relationships and had inhibitor pharmacology and ion selectivity consistent with cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel activity. Zymography and Western blot showed significant expression of MMP-2 in Calu-3 cells. Moreover, anti-MMP-2 antibodies (1 microg/mL) increased whole-cell current and I(sc), whereas human recombinant MMP-2 (10 ng/mL) reduced it. We also studied the expression of MMPs and the effects of phenanthroline on whole-cell current in A549 cells, which are derived from airway surface epithelium and do not express CFTR Cl- channels. While these cells also showed significant expression of MMP-2, inhibition of this enzyme with phenanthroline exerted no significant effect on whole-cell current. It is concluded that MMP-2 is involved in the regulation of CFTR Cl- channels in human airways. PMID:10535713

Duszyk, M; Shu, Y; Sawicki, G; Radomski, A; Man, S F; Radomski, M W

1999-07-01

155

Inhibition of gastric emptying.  

PubMed

In studies aimed at defining the role of amylin in glucose control, elevations of postprandial glucose concentration were blunted in subjects infused with the human amylin analog, pramlintide (Kolterman et al., 1995, 1996). An effect similar to blunt glucose excursions was observed by Brown and others during infusions of amylin in dogs trained to drink glucose (Brown et al., 1994). The effect of pramlintide in humans was present when glucose was administered orally, but not when administered intravenously, suggesting that the effect was due to a deceleration of glucose uptake from the meal, rather than an acceleration of its metabolism (Kolterman et al., 1995). Since amylin did not affect the rate of glucose transit across exteriorized gut loops (Young and Gedulin, 2000), it was proposed that blunting of postprandial glucose profiles could reflect effects on gastric emptying. Rates of gastric emptying have been determined using three different approaches: (1) by measurement of remnant dye found in acutely excised stomachs, (2) by the systemic appearance of labels that are not significantly absorbed until they leave the stomach (e.g., labeled glucose, acetaminophen, 13C-labeled volatiles), and (3) by following the passage of radiolabeled meal components scintigraphically, with a gamma-camera. Amylin and/or pramlintide were shown to potently inhibit gastric emptying by the first method in animals (Clementi et al., 1996; Young et al., 1995a, 1996b), by the second method in animals (Gedulin et al., 1995; Young et al., 1995a, 1996a) and in humans, including those with type 1 and type 2 diabetes (Burrell et al., 2003b; Hücking et al., 2000; Kong et al., 1998; Lee et al., 2000; Vella et al., 2002), and by scintigraphy in patients with type 1 diabetes (Kong et al., 1997, 1998) and in nondiabetic subjects (Samsom et al., 2000). Depending upon dose, responses ranged from a slowing of emptying rate (e.g., by approximately 50%) to a complete cessation. In rats, amylin was 15-fold more potent on a molar basis than glucagon-like peptide-1 (GLP-1) and 20-fold more potent than cholecystokinin octapeptide (CCK-8) for inhibition of gastric emptying (Young et al., 1996b). It was the most potent mammalian peptide of 21 tested for this action (Gedulin et al., 1996b). Amylin inhibition of gastric emptying appears to be mediated by a central mechanism (Clementi et al., 1996; Dilts et al., 1997; Young et al.,2000). An intact vagus nerve (Jodka et al., 1996) and an intact area postrema (Edwards et al., 1998) are required for the effect. In rats that underwent total subdiaphragmatic vagotomy or surgical ablation of the area postrema, amylin was no longer effective at inhibiting gastric emptying (Edwards et al.,1998). The effect of amylin and amylin agonists (including pramlintide) to inhibit gastric emptying was reversed by insulin-induced hypoglycemia (Gedulin and Young, 1998; Gedulin et al., 1997b,c,d; Young et al., 1996a). This suggests the existence of a glucose-sensitive "fail-safe" mechanism that safeguards against severe hypoglycemia; nutrients ingested in response to the hunger that accompanies hypoglycemia can pass rapidly through the stomach for immediate digestion and absorption, unimpaired by the physiological restraint of amylin that would normally prevail at normal glucose concentrations. It seems likely that amylinergic control of gastric emptying is mediated via neurons in the area postrema shown in brain slices to be activated by amylin, and inhibited by low glucose (Riediger et al., 1999). Such neurons have been proposed to mediate glucoprivic gut reflexes (Adachi et al., 1995). PMID:16492543

Young, Andrew

2005-01-01

156

Recent developments in cyclooxygenase inhibition.  

PubMed

Recent studies of the mechanism and selectivity of inhibition of cyclooxygenase enzymes are reviewed. The structural determinants of inhibition by the non-selective inhibitor, aspirin, and COX-2-selective diarylheterocycles are considered. Kinetic investigations indicate that the time-dependence of binding and inhibition of COX-1 and COX-2 by diarylheterocycles is more complex than originally postulated. The selectivity of inhibition is not determined by differences in the rates of association of the inhibitors with the two enzymes but rather by differences in the rates of dissociation. New strategies for the development of COX-2-selective inhibitors are highlighted. PMID:12432915

Marnett, Lawrence J

2002-08-01

157

Firefly luciferase inhibition.  

PubMed

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. PMID:20655239

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

2010-10-01

158

Pharmacological blockade of the DP2 receptor inhibits cigarette smoke-induced inflammation, mucus cell metaplasia, and epithelial hyperplasia in the mouse lung.  

PubMed

Prostaglandin D(2) (PGD(2)) is one of a family of biologically active lipids derived from arachidonic acid via the action of COX-1 and COX-2. PGD(2) is released from mast cells and binds primarily to two G protein-coupled receptors, namely DP1 and DP2, the latter also known as chemoattractant receptor-homologous molecule expressed on Th2 cells. DP2 is predominantly expressed on eosinophils, Th2 cells, and basophils, but it is also expressed to a lesser extent on monocytes, mast cells, and epithelial cells. Interaction of PGD(2) and its active metabolites with DP2 results in cellular chemotaxis, degranulation, up-regulation of adhesion molecules, and cytokine production. Chronic obstructive pulmonary disease (COPD) is a chronic progressive inflammatory disease characterized by elevated lung neutrophils, macrophages, and CD8+ T lymphocytes and mucus hypersecretion. Cigarette smoke contributes to the etiology of COPD and was used here as a provoking agent in a murine model of COPD. In an acute model, {2'-[(cyclopropanecarbonyl-ethyl-amino)-methyl]-6-methoxy-4'-trifluoro-methyl-biphenyl-3-yl}-acetic acid, sodium salt (AM156) and (5-{2-[(benzoyloxycarbonyl-ethyl-amino)-methyl]-4-trifluoromethyl-phenyl}-pyridin-3-yl)-acetic acid, sodium salt) (AM206), potent DP2 receptor antagonists, dose-dependently inhibited influx of neutrophils and lymphocytes to smoke-exposed airways. In a subchronic model, AM156 and AM206 inhibited neutrophil and lymphocyte trafficking to the airways. Furthermore, AM156 and AM206 treatment inhibited mucus cell metaplasia and prevented the thickening of the airway epithelial layer induced by cigarette smoke. These data suggest that DP2 receptor antagonism may represent a novel therapy for COPD or other conditions characterized by neutrophil influx, mucus hypersecretion, and airway remodeling. PMID:19996299

Stebbins, Karin J; Broadhead, Alex R; Baccei, Christopher S; Scott, Jill M; Truong, Yen P; Coate, Heather; Stock, Nicholas S; Santini, Angelina M; Fagan, Patrick; Prodanovich, Patricia; Bain, Gretchen; Stearns, Brian A; King, Christopher D; Hutchinson, John H; Prasit, Peppi; Evans, Jilly F; Lorrain, Daniel S

2010-03-01

159

Inhibition of erythrocyte invasion and Plasmodium falciparum merozoite surface protein 1 processing by human immunoglobulin G1 (IgG1) and IgG3 antibodies.  

PubMed

Antigen-specific antibodies (Abs) to the 19-kDa carboxy-terminal region of Plasmodium falciparum merozoite surface protein 1 (MSP1(19)) play an important role in protective immunity to malaria. Mouse monoclonal Abs (MAbs) 12.10 and 12.8 recognizing MSP1(19) can inhibit red cell invasion by interfering with MSP1 processing on the merozoite surface. We show here that this ability is dependent on the intact Ab since Fab and F(ab')(2) fragments derived from MAb 12.10, although capable of binding MSP1 with high affinity and competing with the intact antibody for binding to MSP1, were unable to inhibit erythrocyte invasion or MSP1 processing. The DNA sequences of the variable (V) regions of both MAbs 12.8 and 12.10 were obtained, and partial amino acid sequences of the same regions were confirmed by mass spectrometry. Human chimeric Abs constructed by using these sequences, which combine the original mouse V regions with human gamma1 and gamma3 constant regions, retain the ability to bind to both parasites and recombinant MSP1(19), and both chimeric human immunoglobulin G1s (IgG1s) were at least as good at inhibiting erythrocyte invasion as the parental murine MAbs 12.8 and 12.10. Furthermore, the human chimeric Abs of the IgG1 class (but not the corresponding human IgG3), induced significant NADPH-mediated oxidative bursts and degranulation from human neutrophils. These chimeric human Abs will enable investigators to examine the role of human Fcgamma receptors in immunity to malaria using a transgenic parasite and mouse model and may prove useful in humans for neutralizing parasites as an adjunct to antimalarial drug therapy. PMID:19805526

Lazarou, Maria; Guevara Patiño, José A; Jennings, Richard M; McIntosh, Richard S; Shi, Jianguo; Howell, Steven; Cullen, Eilish; Jones, Tarran; Adame-Gallegos, Jaime R; Chappel, Jonathan A; McBride, Jana S; Blackman, Michael J; Holder, Anthony A; Pleass, Richard J

2009-12-01

160

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 Central

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-6686–936). BAG-6686–936 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-6686–936 inhibits NKp30-dependent signaling, interferon-? 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-6686–936 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. PMID:24133212

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

2013-01-01

161

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

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.

Zheng, De-Hua [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China)] [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China); Dou, Li-Ping [Department of Hematology, Chinese PLA General Hospital, No. 28 Fu-Xing Road, Beijing 100853 (China)] [Department of Hematology, Chinese PLA General Hospital, No. 28 Fu-Xing Road, Beijing 100853 (China); Wei, Yu-Xiang; Du, Guo-Sheng; Zou, Yi-Ping; Song, Ji-Yong; Zhu, Zhi-Dong; Cai, Ming; Qian, Ye-Yong [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China)] [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China); Shi, Bing-Yi, E-mail: shibingyi@medmail.com.cn [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China)] [Organ Transplant Center, Chinese PLA 309th Hospital, No. 17A Hei-Shan-Hu Road, Beijing 100091 (China)

2010-05-14

162

HIV-1 Vpu Antagonism of Tetherin Inhibits Antibody-Dependent Cellular Cytotoxic Responses by Natural Killer Cells  

PubMed Central

ABSTRACT The type I interferon-inducible factor tetherin retains virus particles on the surfaces of cells infected with vpu-deficient human immunodeficiency virus type 1 (HIV-1). While this mechanism inhibits cell-free viral spread, the immunological implications of tethered virus have not been investigated. We found that surface tetherin expression increased the antibody opsonization of vpu-deficient HIV-infected cells. The absence of Vpu also stimulated NK cell-activating Fc?RIIIa signaling and enhanced NK cell degranulation and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). The deletion of vpu in HIV-1-infected primary CD4+ T cells enhanced the levels of antibody binding and Fc receptor signaling mediated by HIV-positive-patient-derived antibodies. The magnitudes of antibody binding and Fc signaling were both highly correlated to the levels of tetherin on the surfaces of infected primary CD4 T cells. The affinity of antibody binding to Fc?RIIIa was also found to be critical in mediating efficient Fc activation. These studies implicate Vpu antagonism of tetherin as an ADCC evasion mechanism that prevents antibody-mediated clearance of virally infected cells. IMPORTANCE The ability of the HIV-1 accessory factor to antagonize tetherin has been considered to primarily function by limiting the spread of virus by preventing the release of cell-free virus. This study supports the hypothesis that a major function of Vpu is to decrease the recognition of infected cells by anti-HIV antibodies at the cell surface, thereby reducing recognition by antibody-dependent clearance by natural killer cells. PMID:24623433

Alvarez, Raymond A.; Hamlin, Rebecca E.; Monroe, Anthony; Moldt, Brian; Hotta, Mathew T.; Rodriguez Caprio, Gabriela; Fierer, Daniel S.; Simon, Viviana

2014-01-01

163

Inhibition of Pyk2 blocks lung inflammation and injury in a mouse model of acute lung injury  

PubMed Central

Background Proline-rich tyrosine kinase 2 (Pyk2) is essential in neutrophil degranulation and chemotaxis in vitro. However, its effect on the process of lung inflammation and edema formation during LPS induced acute lung injury (ALI) remains unknown. The goal of the present study was to determine the effect of inhibiting Pyk2 on LPS-induced acute lung inflammation and injury in vivo. Methods C57BL6 mice were given either 10 mg/kg LPS or saline intratracheally. Inhibition of Pyk2 was effected by intraperitoneal administration TAT-Pyk2-CT 1 h before challenge. Bronchoalveolar lavage analysis of cell counts, lung histology and protein concentration in BAL were analyzed at 18 h after LPS treatment. KC and MIP-2 concentrations in BAL were measured by a mouse cytokine multiplex kit. The static lung compliance was determined by pressure-volume curve using a computer-controlled small animal ventilator. The extravasated Evans blue concentration in lung homogenate was determined spectrophotometrically. Results Intratracheal instillation of LPS induced significant neutrophil infiltration into the lung interstitium and alveolar space, which was attenuated by pre-treatment with TAT-Pyk2-CT. TAT-Pyk2-CT pretreatment also attenuated 1) myeloperoxidase content in lung tissues, 2) vascular leakage as measured by Evans blue dye extravasation in the lungs and the increase in protein concentration in bronchoalveolar lavage, and 3) the decrease in lung compliance. In each paradigm, treatment with control protein TAT-GFP had no blocking effect. By contrast, production of neutrophil chemokines MIP-2 and keratinocyte-derived chemokine in the bronchoalveolar lavage was not reduced by TAT-Pyk2-CT. Western blot analysis confirmed that tyrosine phosphorylation of Pyk2 in LPS-challenged lungs was reduced to control levels by TAT-Pyk2-CT pretreatment. Conclusions These results suggest that Pyk2 plays an important role in the development of acute lung injury in mice and that pharmacological inhibition of Pyk2 might provide a potential therapeutic strategy in the pretreatment for patients at imminent risk of developing acute lung injury. PMID:22257498

2012-01-01

164

1,25(OH)2 vitamin D3-dependent inhibition of platelet Ca2+ signaling and thrombus formation in klotho-deficient mice.  

PubMed

Platelets are activated by increased cytosolic Ca(2+) concentration ([Ca(2+)]i) following store-operated calcium entry (SOCE) accomplished by calcium-release-activated calcium (CRAC) channel moiety Orai1 and its regulator STIM1. In other cells, Ca(2+) transport is regulated by 1,25(OH)2 vitamin D3 [1,25(OH)2D3]. 1,25(OH)2D3 formation is inhibited by klotho and excessive in klotho-deficient mice (kl/kl). The present study explored the effect of klotho deficiency on platelet Ca(2+) signaling and activation. Platelets and megakaryocytes isolated from WT and kl/kl-mice were analyzed by RT-PCR, Western blotting, confocal microscopy, Fura-2-fluorescence, patch clamp, flow cytometry, aggregometry, and flow chamber. STIM1/Orai1 transcript and protein levels, SOCE, agonist-induced [Ca(2+)]i increase, activation-dependent degranulation, integrin ?IIb?3 activation and aggregation, and thrombus formation were significantly blunted in kl/kl platelets (by 27-90%). STIM1/Orai1 transcript and protein levels, as well as CRAC currents, were significantly reduced in kl/kl megakaryocytes (by 38-73%) and 1,25(OH)2D3-treated WT megakaryocytes. Nuclear NF-?B subunit p50/p65 abundance was significantly reduced in kl/kl-megakaryocytes (by 51-76%). Transfection with p50/p65 significantly increased STIM1/Orai1 transcript and protein levels in megakaryocytic MEG-01 cells (by 46-97%). Low-vitamin D diet (LVD) of kl/kl mice normalized plasma 1,25(OH)2D3 concentration and function of platelets and megakaryocytes. Klotho deficiency inhibits platelet Ca(2+) signaling and activation, an effect at least partially due to 1,25(OH)2D3-dependent down-regulation of NF-?B activity and STIM1/Orai1 expression in megakaryocytes. PMID:24522202

Borst, Oliver; Münzer, Patrick; Schmid, Evi; Schmidt, Eva-Maria; Russo, Antonella; Walker, Britta; Yang, Wenting; Leibrock, Christina; Szteyn, Kalina; Schmidt, Sebastian; Elvers, Margitta; Faggio, Caterina; Shumilina, Ekaterina; Kuro-o, Makoto; Gawaz, Meinrad; Lang, Florian

2014-05-01

165

Presynaptic inhibition of elicited neurotransmitter release  

Microsoft Academic Search

Activation of presynaptic receptors for a variety of neurotransmitters and neuromodulators inhibits transmitter release at many synapses. Such presynaptic inhibition might serve as a means of adjusting synaptic strength or preventing excessive transmitter release, or both. Previous evidence showed that presynaptic modulators inhibit Ca2+ channels and activate K+ channels at neuronal somata. These modulators also inhibit spontaneous transmitter release by

Ling-Gang Wu; Peter Saggau

1997-01-01

166

Bacterial Inhibition by Electrical Stimulation  

PubMed Central

Significance: Much evidence shows that electrical stimulation (ES) promotes the wound healing process. The inhibitory effect of ES on bacterial growth has been proposed as a mechanism to explain the useful effects of ES on wound healing. Bacterial burden has been associated with chronic wounds. The extensive use of antibiotics can lead to the spread of multiple drug resistant bacteria. Whether biophysical energies, such as ES, can be used as a treatment modality against pathogenic microorganisms remains an open question. Recent Advances: The research literature provides evidence for useful effects of ES in terms of inhibition of bacterial growth. The type of ES, its polarity, and the intensity of the current play a major role in establishment of antibacterial effects. Both direct current (DC) and high voltage pulse current are more effective at inhibiting bacterial growth than are other types of ES. The exact mechanism underlying the antibacterial effects of ES is not clear. Critical Issues: Available evidence indicates that microampere DC (?ADC) is better than other ES types for inhibition of bacterial growth. The results of most studies also support the application of cathodal current for bacterial growth inhibition. The current intensity of ES would appear to be tolerable by humans if used clinically for treatment of infected wounds. Future Directions: The cathodal ?ADC appears to be more effective for inhibition of microorganism growth. Further research, especially in vivo, is necessary to clarify the inhibitory effects of ES on wound bacterial infections. PMID:24761349

Asadi, Mohammad Reza; Torkaman, Giti

2014-01-01

167

Action spectra for photosynthetic inhibition  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

168

Memory inhibition and energy regulation  

Microsoft Academic Search

At a simple behavioral level, food intake and body weight regulation depend on one's ability to balance the tendency to seek out and consume food with the ability to suppress or inhibit those responses. Accordingly, any factor that augments the tendency to engage in food seeking and eating or that interferes with the suppression of these behaviors could produce (a)

T. L. Davidson; Scott E. Kanoski; Elwood K. Walls; Leonard E. Jarrard

2005-01-01

169

Human cytomegalovirus inhibits erythropoietin production.  

PubMed

Anemia is a feature of CKD and a complication of renal transplantation, often caused by impaired production of erythropoietin. The kidney is a target organ for human cytomegalovirus (hCMV) in such patients, but it is not known whether hCMV effects erythropoietin production. We found that kidneys from patients with CKD were positive for hCMV protein and that blood levels of hCMV IgG inversely correlated with red blood cell count. In mice, systemic murine cytomegalovirus infection decreased serum erythropoietin levels. In human erythropoietin-producing cells, hCMV inhibited hypoxia-induced expression of erythropoietin mRNA and protein. hCMV early gene expression was responsible, as ultraviolet-inactivated virus had no effect and valganciclovir treatment showed that late gene expression was nonessential. Hypoxia-induced gene transcription is controlled by the transcription factors hypoxia-inducible transcription factor (HIF)-1? and HIF2?, which are constitutively produced but stable only under low oxygen conditions. We found that hCMV inhibited constitutive production of HIF2? mRNA. HIF2? is thought to be the master regulator of erythropoietin transcription. Single-cell analysis revealed that nuclear accumulation of HIF2? was inhibited in hCMV-infected cells, and the extent of inhibition correlated with hCMV protein expression. Our findings suggest that renal hCMV infection could induce or exacerbate anemia in patients. PMID:24722450

Butler, Lynn M; Dzabic, Mensur; Bakker, Frank; Davoudi, Belghis; Jeffery, Hannah; Religa, Piotr; Bojakowski, Krzysztof; Yaiw, Koon-Chu; Rahbar, Afsar; Söderberg-Naucler, Cecilia

2014-08-01

170

Methanogenic Inhibition by Arsenic Compounds  

Microsoft Academic Search

The acute acetoclastic methanogenic inhibition of several inorganic and organic arsenicals was assayed. Trivalent species, i.e., methylarsonous acid and arsenite, were highly inhibitory, with 50% inhibitory concen- trations of 9.1 and 15.0 M, respectively, whereas pentavalent species were generally nontoxic. The nitrophe- nylarsonate derivate, roxarsone, displayed moderate toxicity. Arsenic is a high-priority pollutant that is widely distributed in the environment.

Reyes Sierra-Alvarez; Irail Cortinas; Umur Yenal; Jim A. Field

2004-01-01

171

Behavioral inhibition: A neurobiological perspective  

Microsoft Academic Search

Behavioral inhibition (BI) during early childhood has been associated with subsequent development of anxiety disorders. However,\\u000a understanding of the neuroanatomical substrates of BI in humans generally has not kept pace with that of anxiety disorders.\\u000a Recent interpretations and implementations of Gray’s and Kagan’s concepts of BI are examined from the perspective of current\\u000a neurobiological models. Particular attention is given to

Barak E. Morgan

2006-01-01

172

Inhibition of Cyclooxygenases by Dipyrone  

PubMed Central

Background and Purpose: Dipyrone is a potent analgesic drug that has been demonstrated to inhibit cyclooxygenase (COX). In contrast to classical COX-inhibitors, such as aspirin-like drugs, dipyrone has no anti-inflammatory effect and a low gastrointestinal toxicity, indicating a different mode of action. Here, we aimed to investigate the effects of dipyrone on COX. Experimental approach: The four major metabolites of dipyrone, including the two pharmacologically active metabolites, 4-methyl-amino-antipyrine (MAA) and amino-antipyrine (AA), were used to characterise their binding to COX and haem as well as their effects on the biochemical properties of COX. Mass spectrometry, UV and visible photometry were used to study binding and prostaglandin production. Levels of anti-oxidant enzymes were assessed by Western blotting. Key results: The pharmacologically active metabolites of dipyrone, MAA and AA, did not inhibit COX activity in vitro like classical COX inhibitors, but instead redirected the prostaglandin synthesis, ruling out inhibition of COX through binding to its active site. We found that MAA and AA formed stable complexes with haem and reacted with hydrogen peroxide in presence of haem, ferrous ions (Fe2+) or COX. Moreover, MAA reduced Fe3+ to Fe2+ and accordingly increased lipid peroxidation and the expression of anti-oxidant enzymes in cultured cells and in vivo. Conclusions and implications: Our data suggest that the pharmacologically active metabolites of dipyrone inhibit COX activity by sequestering radicals which initiate the catalytic activity of this enzyme or through the reduction of the oxidative states of the COX protein. PMID:17435797

Pierre, S C; Schmidt, R; Brenneis, C; Michaelis, M; Geisslinger, G; Scholich, K

2007-01-01

173

Lateral Thinking about Lateral Inhibition  

Microsoft Academic Search

IT has recently been asserted1 that the well known apparent expansion of acute angles is due not to the lateral inhibition proposed by Blakemore et al.2, but to an adaptation effect similar to the Gibson tilt after-effect3,4. The arguments by which Coltheart arrives at this conclusion, however, seem to us to be based on a complete misreading, and hence misrepresentation,

Colin Blakemore; R. H. S. Carpenter; M. A. GEORGESON

1971-01-01

174

A? Association Inhibition by Transferrin  

PubMed Central

The iron-transport glycoprotein transferrin has recently been shown to serve as a potent inhibitor of A? self-association. Although this novel, to our knowledge, inhibitory function of transferrin is of potential therapeutic interest for the treatment of Alzheimer’s disease, the underlying mechanism is still not fully understood. Although it has been shown that the Fe(III) sequestration by transferrin reduces oxidative damage and A? aggregation, it is not clear whether transferrin is also able to inhibit A? self-association through direct binding of A?. Here, using saturation transfer and off-resonance relaxation NMR spectroscopy, we show that transferrin inhibits A? aggregation also by preferentially binding A? oligomers and outcompeting A? monomers that would otherwise cause the growth of the A? oligomers into larger assemblies. This inhibitory mechanism is different from the iron-sequestration model, but it is qualitatively similar to a mechanism previously proposed for the inhibition of A? self-association by another plasma and cerebrospinal fluid protein, i.e., human serum albumin. These results suggest that A? monomer competition through direct A? oligomer binding might be a general strategy adopted by proteins in plasma and cerebrospinal fluid to prevent A? aggregation. PMID:23870268

Raditsis, Annie V.; Milojevic, Julijana; Melacini, Giuseppe

2013-01-01

175

A? association inhibition by transferrin.  

PubMed

The iron-transport glycoprotein transferrin has recently been shown to serve as a potent inhibitor of A? self-association. Although this novel, to our knowledge, inhibitory function of transferrin is of potential therapeutic interest for the treatment of Alzheimer's disease, the underlying mechanism is still not fully understood. Although it has been shown that the Fe(III) sequestration by transferrin reduces oxidative damage and A? aggregation, it is not clear whether transferrin is also able to inhibit A? self-association through direct binding of A?. Here, using saturation transfer and off-resonance relaxation NMR spectroscopy, we show that transferrin inhibits A? aggregation also by preferentially binding A? oligomers and outcompeting A? monomers that would otherwise cause the growth of the A? oligomers into larger assemblies. This inhibitory mechanism is different from the iron-sequestration model, but it is qualitatively similar to a mechanism previously proposed for the inhibition of A? self-association by another plasma and cerebrospinal fluid protein, i.e., human serum albumin. These results suggest that A? monomer competition through direct A? oligomer binding might be a general strategy adopted by proteins in plasma and cerebrospinal fluid to prevent A? aggregation. PMID:23870268

Raditsis, Annie V; Milojevic, Julijana; Melacini, Giuseppe

2013-07-16

176

Zeamatin Inhibits Trypsin and ?-Amylase Activities  

PubMed Central

Zeamatin is a 22-kDa protein isolated from Zea mays that has antifungal activity against human and plant pathogens. Unlike other pathogenesis-related group 5 proteins, zeamatin inhibits insect ?-amylase and mammalian trypsin activities. It is of clinical significance that zeamatin did not inhibit human ?-amylase activity and inhibited mammalian trypsin activity only at high molar concentrations. PMID:11319124

Schimoler-O'Rourke, Rebecca; Richardson, Michael; Selitrennikoff, Claude P.

2001-01-01

177

MOLECULAR MECHANISM OF EGCG INHIBITION OF ANGIOGENESIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Green tea may prevent cancer development via several mechanisms. One of the mechanisms is believed to be through its inhibition of tumor angiogenesis. Earlier, we have shown that the green tea catechins including epigallocatechin gallate (EGCG) inhibit angiogenesis through the inhibition of Akt and ...

178

Method for decreasing radiation load in puva therapy  

SciTech Connect

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.

Wolff, K.

1987-02-10

179

Heparin inhibits phagocytosis by polymorphonuclear leukocytes.  

PubMed Central

Phagocytosis of unopsonized Salmonella typhimurium 395, MR-10, opsonized Salmonella typhimurium 395 MS, and Staphylococcus epidermidis by rabbit polymorphonuclear leukocytes was inhibited by heparin at concentrations as low as 0.5 U/ml. Inhibition was dose dependent and nearly complete at 20 U/ml. Provided that heparin concentrations did not exceed 100 U/ml, inhibition could be largely reversed by washing. Heparin also reversibly inhibited the adherence of polymorphonuclear leukocytes to glass. In contrast, hexose monophosphate shunt activity of polymorphonuclear leukocytes stimulated by noningested S. typhimurium MR-10 or Streptococcus pyogenes B14 was not inhibited by heparin at concentrations as high as 100 U/ml. PMID:7012030

Victor, M; Weiss, J; Elsbach, P

1981-01-01

180

Self-regulation, ego depletion, and inhibition.  

PubMed

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. PMID:25149821

Baumeister, Roy F

2014-12-01

181

Citrate inhibition of snake venom proteases.  

PubMed

Thirty snake venoms had a citrate content of 2.3 to 12.9%, dry basis, by an aconitase isocitric dehydrogenase coupled enzyme assay. This is a venom concentration range of approximately 30 to 150 mM citrate assuming 25% venom solids content. Inhibition of snake venom protease activity by the addition of exogenous citrate was obtained using azure blue hide powder and azocasein as substrates. Protease inhibitions of 7.5% for Crotalus atrox venom to 78% for Bothrops picadoi venom were observed with citrate. Complete inhibition of snake venom protease activity by citrate was not observed. Bothrops asper (Pacifico) venom showed a 41% protease inhibition by citrate with azocasein as the substrate and 46% inhibition of Bothrops asper (Alantico) venom protease with azure blue hide power as a substrate. Trypsin was not inhibited in this system. Citrate may inhibit some venom protease activity by forming a complex with the zinc of zinc-dependent enzymes. reserved. PMID:9839664

Odell, G V; Ferry, P C; Vick, L M; Fenton, A W; Decker, L S; Cowell, R L; Ownby, C L; Gutierrez, J M

1998-12-01

182

Recruitment of neutrophils during IgE-dependent cutaneous late phase reactions in the mouse is mast cell-dependent. Partial inhibition of the reaction with antiserum against tumor necrosis factor-alpha.  

PubMed Central

Much of the clinically important pathology associated with IgE-dependent disorders is thought to reflect the actions of the blood-borne leukocytes recruited during these responses. To evaluate the extent to which mast cells are responsible for the leukocyte infiltration associated with IgE-dependent cutaneous reactions, we attempted to elicit these responses in normal mice, genetically mast cell-deficient W/Wv mice, and in W/Wv mice selectively repaired of their mast cell deficiency by the intradermal injection of cultured mast cells derived from the congenic normal (+/+) mice. We found that the tissue swelling associated with IgE-dependent passive cutaneous anaphylaxis reactions developed rapidly and diminished markedly from 2 to 4 h after antigen challenge, but remained detectable for at least 24 h after elicitation of the responses. Infiltration of leukocytes (predominantly neutrophils) also occurred at these sites, but reached maximal levels 6-12 h after antigen challenge, persisted at high levels for 24 h, and largely waned by 48 h. Virtually all of the tissue swelling and leukocyte infiltration associated with IgE-dependent cutaneous reactions was mast cell dependent. Intradermal injection of 40 U of recombinant murine TNF-alpha (rmTNF-alpha) elicited neutrophil infiltration similar in magnitude and kinetics to that observed after IgE-dependent mast cell degranulation. A rabbit anti-rmTNF-alpha (R anti-rmTNF-alpha) antiserum, which was able to inhibit 84% of the neutrophil infiltration observed after i.d. injection of rmTNF-alpha, inhibited IgE-, and mast cell-dependent leukocyte infiltration by 47 +/- 7% in three separate experiments. These findings indicate that TNF-alpha contributes to mast cell-dependent recruitment of leukocytes during IgE-dependent cutaneous late phase reactions, but suggest that other mast cell-associated mediators probably also contribute to this response. Images PMID:1991831

Wershil, B K; Wang, Z S; Gordon, J R; Galli, S J

1991-01-01

183

Involvement of Heme Oxygenase1 in Kaempferol-Induced Anti-Allergic Actions in RBL-2H3 Cells  

Microsoft Academic Search

Kaempferol is one of the most commonly found dietary flavonoids. The exposure to kaempferol is known to inhibit degranulation\\u000a from mast cells, but the inhibitory mechanism of degranulation has not been clarified yet. In this study, we investigated\\u000a the involvement of heme oxygenase (HO)-1 in the anti-allergic action of kaempferol against degranulation in rat basophilic\\u000a leukemia (RBL-2H3) cells. Our results

Etsuko Hirose; Miyoko Matsushima; Kenzo Takagi; Yui Ota; Keiko Ishigami; Tatsuya Hirayama; Yuta Hayashi; Toshinobu Nakamura; Naozumi Hashimoto; Kazuyoshi Imaizumi; Kenji Baba; Yoshinori Hasegawa; Tsutomu Kawabe

2009-01-01

184

Kinetics and Inhibition of Reductive Dechlorination of Chlorinated  

E-print Network

Kinetics and Inhibition of Reductive Dechlorination of Chlorinated Ethylenes by Two Different Mixed inhibition between chlorinated ethylenes. The more chlorinated ethylenes inhibited the reductive dechlorination of the less chlorinated ethylenes, while the less chlorinated ethylenes weakly inhibited

Semprini, Lewis

185

Action inhibition in Tourette syndrome.  

PubMed

Tourette syndrome is a neuropsychiatric disorder characterized by tics. Tic generation is often linked to dysfunction of inhibitory brain networks. Some previous behavioral studies found deficiencies in inhibitory motor control in Tourette syndrome, but others suggested normal or even better-than-normal performance. Furthermore, neural correlates of action inhibition in these patients are poorly understood. We performed event-related functional magnetic resonance imaging during a stop-signal reaction-time task in 14 uncomplicated adult Tourette patients and 15 healthy controls. In patients, we correlated activations in stop-signal reaction-time task with their individual motor tic frequency. Task performance was similar in both groups. Activation of dorsal premotor cortex was stronger in the StopSuccess than in the Go condition in healthy controls. This pattern was reversed in Tourette patients. A significant positive correlation was present between motor tic frequency and activations in the supplementary motor area during StopSuccess versus Go in patients. Inhibitory brain networks differ between healthy controls and Tourette patients. In the latter the supplementary motor area is probably a key relay of inhibitory processes mediating both suppression of tics and inhibition of voluntary action. PMID:24995958

Ganos, Christos; Kühn, Simone; Kahl, Ursula; Schunke, Odette; Feldheim, Jan; Gerloff, Christian; Roessner, Veit; Bäumer, Tobias; Thomalla, Götz; Haggard, Patrick; Münchau, Alexander

2014-10-01

186

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

SciTech Connect

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.

Rajesh, Mohanraj [Section On Oxidative Stress Tissue Injury, Laboratory of Physiological Studies, NIAAA, National Institutes of Health, 5625 Fishers Lane, MSC-9413, Bethesda, MD 20892-9413 (United States); Mukhopadhyay, Partha [Section On Oxidative Stress Tissue Injury, Laboratory of Physiological Studies, NIAAA, National Institutes of Health, 5625 Fishers Lane, MSC-9413, Bethesda, MD 20892-9413 (United States); Batkai, Sandor [Section On Oxidative Stress Tissue Injury, Laboratory of Physiological Studies, NIAAA, National Institutes of Health, 5625 Fishers Lane, MSC-9413, Bethesda, MD 20892-9413 (United States); Godlewski, Grzegorz [Section On Oxidative Stress Tissue Injury, Laboratory of Physiological Studies, NIAAA, National Institutes of Health, 5625 Fishers Lane, MSC-9413, Bethesda, MD 20892-9413 (United States); Hasko, Gyoergy [Department of Surgery, UMDNJ-New Jersey Medical School, Newark, NJ 07103 (United States); Liaudet, Lucas [Department of Intensive Care Medicine, University Hospital, 1011 Lausanne (Switzerland); Pacher, Pal [Section On Oxidative Stress Tissue Injury, Laboratory of Physiological Studies, NIAAA, National Institutes of Health, 5625 Fishers Lane, MSC-9413, Bethesda, MD 20892-9413 (United States)]. E-mail: pacher@mail.nih.gov

2006-11-17

187

Tetrahydrocannabinol inhibition of macrophage nitric oxide production  

Microsoft Academic Search

?9-Tetrahydrocannabinol (THC) inhibited nitric oxide (NO.) production by mouse peritoneal macrophages activated by bacterial endotoxin lipopolysaccharide (LPS) and interferon-? (IFN)-?). Inhibition of NO. production was noted at THC concentrations as low as 0.5 ?g\\/mL, and was nearly total at 7 ?g\\/mL. Inhibition was greatest if THC was added 1–4 hr before induction of nitric oxide synthase (NOS) by LPS and

Ronald G. Coffey; Yoshimasa Yamamoto; Elizabeth Snella; Susan Pross

1996-01-01

188

Inhibition drives early feature-based attention  

PubMed Central

Attention can modulate processing of visual input according to task-relevant features, even as early as ~100 ms after stimulus presentation. In the present study, ERP and behavioral data reveal that inhibition of distractor features, rather than activation of target features, is the primary driver of early feature-based selection in human observers. This discovery of inhibition consistent with task goals during early visual processing suggests that inhibition plays a much larger role at an earlier stage of target selection than previously recognized, and highlights the importance of understanding the role of inhibition (in addition to activation) in attention. PMID:24390823

Moher, Jeff; Lakshmanan, Balaji M.; Egeth, Howard E.; Ewen, Joshua B.

2013-01-01

189

Magnetic catalysis versus magnetic inhibition.  

PubMed

We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former enhances the chiral-symmetry breaking at finite B according to the magnetic catalysis, while the latter suppresses the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model, we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the magnetic inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B. PMID:23373911

Fukushima, Kenji; Hidaka, Yoshimasa

2013-01-18

190

Behavioral Inhibition: Temperament or Prodrome?  

PubMed

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

Pérez-Edgar, Koraly E; Guyer, Amanda E

2014-09-01

191

Magnetic Catalysis vs Magnetic Inhibition  

E-print Network

We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06

192

STUDIES ON PNEUMOCOCCUS GROWTH INHIBITION  

PubMed Central

Somewhat discordant results which have been reported by others who have investigated the property of the whole blood of resistant animals to cause inhibition of growth or death of pneumococci have led us to investigate this matter and to develop a new technique in which the conditions as they are present in the animal body are more nearly imitated. The observations already made have rendered it probable that phagocytosis plays some rôle in any destructive power for pneumococcus which whole blood possesses. We have, therefore, employed mixtures of serum and leucocytes in our tests, since when blood is coagulated the conditions become highly artificial. Furthermore, in order to imitate more nearly the conditions in the circulating blood the mixtures have been constantly, though gently, agitated. For this purpose a specially devised apparatus has been employed. The mixtures of serum and leucocytes have been inoculated with varying numbers of pneumococci in the active growth phase and after varying intervals of time the tubes containing the mixtures of serum, leucocytes, and bacteria have been opened, examined microscopically, and cultures made. Employing this technique it has been found that the growth of pneumococci having low virulence for cats is markedly inhibited in mixtures of cat serum and cat leucocytes. It was impossible to recover pneumococci from the tubes showing no apparent growth, either when the contents were transplanted into various kinds of culture media, or when the contents were injected into mice of a variety highly susceptible to pneumococcus infection. 10,000 times the number of pneumococci sufficient ordinarily to kill a mouse failed to do so after a 24 hour sojourn in the cat serum-leucocyte mixture. Mixtures of dog serum and leucocytes exert a similar action. The serum and leucocytes of animals susceptible to pneumococcus infection (rabbits and guinea pigs,) on the other hand, failed to injure pneumococci even in extremely small quantities. These results indicate that the blood of resistant animals, at least of the dog and cat, possesses destructive properties for pneumococci, and that this destructive power is not possessed by the blood of certain susceptible animals. The experiments suggest that natural immunity depends chiefly, if not entirely, upon this property. The leucocytes play an active part in this process, but whether the destruction of the pneumococci occurs entirely within the leucocytes or not is not determined. That the serum also plays a part is shown by the fact that when the serum of resistant animals was inactivated before being used in the serum-leucocyte mixture, the growth of even very small numbers of pneumococci was not prevented. Further experiments with cat serum and leucocytes were carried out to determine the optimum rate and time of agitation, the amount of serum and leucocytes required, and also the period of incubation necessary for the inhibition of growth and death of the pneumococci to occur. PMID:19868840

Robertson, Oswald H.; Sia, Richard H. P.

1924-01-01

193

Quantum chemical approach of corrosion inhibition  

Microsoft Academic Search

An examination of quantum chemical and corrosion inhibition studies were made to see if any clear links exist between the two. The results of quantum chemical calculations and experimental efficiencies of inhibitors were subjected to correlation analysis. A composite index of some of the key quantum chemical parameters was constructed in order to characterize the inhibition performance of the tested

N. Khalil

2003-01-01

194

Inhibition of Diamine Oxidase Activity by Metronidazole  

Microsoft Academic Search

Metronidazole was found to be a non-competitive inhibitor of man, rabbit and rat intestinal diamine oxidases with an inhibition constant value of ? 10?4 M. The purified bovine serum amine oxidase was not inhibited, whereas the purified swine kidney enzyme gave similar results. These findings suggest that metronidazole and similar compounds, used as antibacterial and antiprotozoal drugs, should be given

O. Befani; T. S. Shiozaki; P. Turini; P. Gerosa; B. Mondovi

1995-01-01

195

Hydrogen production from inhibited anaerobic composters  

Microsoft Academic Search

This paper investigated hydrogen production from a model lignocellulosic waste in inhibited solid substrate anaerobic digesters. Acetylene at 1% vv in the headspace was as effective as bromoethanesulfonate in inhibiting methanogenic activity in batch anaerobic composters containing 25% (wv) total organic solids inoculated with an undefined cellulotytic consortium derived from anaerobic digesters. Acetylene also had no effect on the rate

R. Sparling; D. Risbey; H. M. Poggi-Varaldo

1997-01-01

196

Optimal Decision Making in Neural Inhibition Models  

ERIC Educational Resources Information Center

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…

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

2012-01-01

197

Inhibition of diamine oxidase by antimalarial drugs  

Microsoft Academic Search

The antimalarial drugs amodiaquine, quinacrine and chloroquine inhibit the catabolism of putrescine by the rat. Amodiaquine, the most potent of the three, does so in a dose-dependent fashion. This is attributed to the action in vivo of the drugs on diamine oxidase, an enzyme that is inhibited by them in vitro.

Kelvin Ma; Theodore L. Sourkes

1980-01-01

198

A Qualitative Approach to Enzyme Inhibition  

ERIC Educational Resources Information Center

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…

Waldrop, Grover L.

2009-01-01

199

Inhibition and Facilitation of Nucleic Acid Amplification  

Microsoft Academic Search

Factors that inhibit the amplification of nucleic acids by PCR are present with target DNAs from many sources. The inhib- itors generally act at one or more of three essential points in the reaction in the following ways: they interfere with the cell lysis necessary for extraction of DNA, they interfere by nucleic acid degradation or capture, and they inhibit

IAN G. WILSON

1997-01-01

200

Response facilitation and inhibition in subliminal priming  

Microsoft Academic Search

The research reviewed in this article has investigated with behavioural, electrophysiological, and functional imaging methods how subliminally presented masked prime stimuli affect response-related processes. An initial response activation triggered by these primes was found to be followed by an inhibition of this response tendency, provided that the initial activation was strong enough to exceed an ‘inhibition threshold’. This biphasic pattern

Martin Eimer; Friederike Schlaghecken

2003-01-01

201

Inhibition of monoamine oxidase by substituted hydrazines  

PubMed Central

1. The initial rate of inhibition of monoamine oxidase by phenethylhydrazine was shown to be similar, in pH-dependence and kinetic properties, to the oxidation of that compound by monoamine oxidase. 2. The time-course of irreversible inhibition of monoamine oxidase by phenethylhydrazine lags behind that of reversible inhibition. 3. Hydralzine was shown to be a reversible competitive inhibitor of monoamine oxidase, but phenylhydrazine is an irreversible inhibitor. Inhibition by the latter compound is not affected by the absence of oxygen, and the presence of substrate exerts no protective action. 4. Hydrazine does not inhibit monoamine oxidase unless a substrate and oxygen are present. 5. Phenethylidenehydrazine was found to be a time-dependent inhibitor of monoamine oxidase and the rate of inhibition was hindered by increasing oxygen concentration. 6. A mechanism for the inhibition of the enzyme by phenethylhydrazine is proposed in which the product of oxidation of this compound is a potent reversible inhibitor and an irreversible inhibitor of the enzyme. A computer simulation of such a mechanism predicts time-courses of inhibition that are in reasonable agreement with those observed experimentally. PMID:4674124

Tipton, Keith F.

1972-01-01

202

Response Inhibition and the Rorschach ‘M’ Response  

Microsoft Academic Search

Previous research indicated that a relationship existed between production of the Rorschach M response and inhibition of motor activity. The present study investigated this relationship under conditions which approximated those involved in the normal process of impulse control. Volunteer college students were used as subjects. Ss who engaged in a response inhibition task subsequently produced significantly more M responses than

Joel Darby; Kees Hofman; Barry Melnick

1967-01-01

203

The inhibition of acquired fear.  

PubMed

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 commonly studied in rodents. Therefore, it seems safe to continue using extinction-based forms of therapy for disorders secondary to acquired fear. Further, it is useful and desirable to device procedures by which the "no US" component of the extinction is strengthened in order to alleviate the symptoms of victims of acquired fear. PMID:15325957

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

2004-01-01

204

Role of mutual inhibition in binocular rivalry.  

PubMed

Binocular rivalry is a phenomenon that occurs when a different image is presented to each eye. The observer generally perceives just one image at a time, with perceptual switches occurring every few seconds. A natural assumption is that this perceptual mutual exclusivity is achieved via mutual inhibition between populations of neurons that encode for either percept. Theoretical models that incorporate mutual inhibition have been largely successful at capturing experimental features of rivalry, including Levelt's propositions, which characterize perceptual dominance durations as a function of image contrasts. However, basic mutual inhibition models do not fully comply with Levelt's fourth proposition, which states that percepts alternate faster as the stimulus contrasts to both eyes are increased simultaneously. This theory-experiment discrepancy has been taken as evidence against the role of mutual inhibition for binocular rivalry. Here, we show how various biophysically plausible modifications to mutual inhibition models can resolve this problem. PMID:21775721

Seely, Jeffrey; Chow, Carson C

2011-11-01

205

Progress with proton pump inhibition.  

PubMed Central

The proton pump, a H+/K(+)-ATPase located on the secretory canalicular membrane of the parietal cell, forms the final pathway for gastric acid secretion. Omeprazole is concentrated in the secretory canaliculus, where it is converted to its active form, which binds covalently with the H+/K(+)-ATPase, thus inhibiting acid secretion arising from any stimulus. Meta-analysis has defined the primary determinants for peptic ulcer healing as the degree of acid suppression, the duration of suppression over 24 hours, and the length of treatment. The longer duration of acid suppression with omeprazole, particularly during the day, when food is ingested and H2-receptor antagonists are less effective, is reflected in the clinical superiority for symptom relief and ulcer healing and especially for the treatment of erosive esophagitis. Extensive clinical experience has proved omeprazole to be safe, and concerns over hypergastrinemia, ECL-cell hyperplasia, and carcinoid formation have not been substantiated in humans. Recent evidence has shown that omeprazole suppresses Helicobacter pylori and, in combination with antibiotics, can eradicate this organism in a substantial proportion of patients. This effect may result from enhancement of antibiotic bioavailability and optimizing host defense mechanisms. PMID:1341069

Bell, N. J.; Hunt, R. H.

1992-01-01

206

Reduced surround inhibition in musicians.  

PubMed

To investigate whether surround inhibition (SI) in the motor system is altered in professional musicians, we performed a transcranial magnetic stimulation (TMS) study in 10 professional musicians and 15 age-matched healthy non-musicians. TMS was set to be triggered by self-initiated flexion of the index finger at different intervals ranging from 3 to 1,000 ms. Average motor evoked potential (MEP) amplitudes obtained from self-triggered TMS were normalized to average MEPs of the control TMS at rest and expressed as a percentage. Normalized MEP amplitudes of the abductor digiti minimi (ADM) muscles were compared between the musicians and non-musicians with the primary analysis being the intervals between 3 and 80 ms (during the movement). A mixed-design ANOVA revealed a significant difference in normalized ADM MEPs during the index finger flexion between groups, with less SI in the musicians. This study demonstrated that the functional operation of SI is less strong in musicians than non-musicians, perhaps due to practice of movement synergies involving both muscles. Reduced SI, however, could lead susceptible musicians to be prone to develop task-specific dystonia. PMID:22543743

Shin, Hae-Won; Kang, Suk Y; Hallett, Mark; Sohn, Young H

2012-06-01

207

Shed syndecan-2 inhibits angiogenesis  

PubMed Central

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 ?1 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

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

2014-01-01

208

Fear inhibition in high trait anxiety.  

PubMed

Trait anxiety is recognized as an individual risk factor for the development of anxiety disorders but the neurobiological mechanisms remain unknown. Here we test whether trait anxiety is associated with impaired fear inhibition utilizing the AX+/BX- conditional discrimination procedure that allows for the independent evaluation of startle fear potentiation and inhibition of fear. Sixty undergraduate students participated in the study--High Trait Anxious: n?=?28 and Low Trait Anxious: n?=?32. We replicated earlier findings that a transfer of conditioned inhibition for startle responses requires contingency awareness. However, contrary to the fear inhibition hypothesis, our data suggest that high trait anxious individuals show a normal fear inhibition of conditioned startle responding. Only at the cognitive level the high trait anxious individuals showed evidence for impaired inhibitory learning of the threat cue. Together with other findings where impaired fear inhibition was only observed in those PTSD patients who were either high on hyperarousal symptoms or with current anxiety symptoms, we question whether impaired fear inhibition is a biomarker for the development of anxiety disorders. PMID:24454969

Kindt, Merel; Soeter, Marieke

2014-01-01

209

Inhibition of muscle force by vanadate.  

PubMed Central

Vanadate (Vi), an analogue of inorganic phosphate (Pi), is known to bind tightly with a long half life to the myosin MgATPase site, producing a complex which inhibits force. Both of these ligands bind to an actin.myosin.ADP state that follows the release of Pi in the enzymatic cycle, and their effects on muscle fibers and proteins in solution provide information on the properties of this state. The inhibition of active force generation began to occur at a [Vi] of 5 microM and was 90% complete at a [Vi] of 1 mM. Hill plots of the inhibition of force by Vi approximated that expected for a simple binding isotherm. Similar plots were obtained at both 25 degrees C and 5 degrees C. A simple binding isotherm is not expected to occur in a muscle fiber where steric constraints imposed by the intact filaments should introduce more complexity into the energetics of ligand binding. The inhibition of MgATPase activity for acto-subfragment-1 to 50% of controls occurred at a [Vi] which was only 20-fold higher than that required to inhibit force generation in fibers to the same level. Some models of actomyosin interactions would predict that the range of [Vi] required for complete force inhibition in fibers and the difference in the [Vi] required for inhibition in fibers and of myosin in solution would both be much larger. PMID:7711244

Wilson, G J; Shull, S E; Cooke, R

1995-01-01

210

Surround inhibition in the motor system.  

PubMed

Surround inhibition is a physiological mechanism to focus neuronal activity in the central nervous system. This so-called center-surround organization is well known in sensory systems, where central signals are facilitated and eccentric signals are inhibited in order to sharpen the contrast between them. There is evidence that this mechanism is relevant to skilled motor behavior, and it is deficient, for example, in the affected primary motor cortex of patients with focal hand dystonia (FHD). While it is still not fully elucidated how surround inhibition is generated in healthy subjects, the process is enhanced with handedness and task difficulty indicating that it may be an important mechanism for the performance of individuated finger movements. In FHD, where involuntary overactivation of muscles interferes with precise finger movements, a loss of intracortical inhibition likely contributes to the loss of surround inhibition. Several intracortical inhibitory networks are modulated differently in FHD compared with healthy subjects, and these may contribute to the loss of surround inhibition. Surround inhibition can be observed and assessed in the primary motor cortex. It remains unclear, however, if the effects are created in the cortex or if they are derived from, or supported by, motor signals that come from the basal ganglia. PMID:21424259

Beck, Sandra; Hallett, Mark

2011-04-01

211

Regulation of Spatial Selectivity by Crossover Inhibition  

PubMed Central

Signals throughout the nervous system diverge into parallel excitatory and inhibitory pathways that later converge on downstream neurons to control their spike output. Converging excitatory and inhibitory synaptic inputs can exhibit a variety of temporal relationships. A common motif is feedforward inhibition, in which an increase (decrease) in excitatory input precedes a corresponding increase (decrease) in inhibitory input. The delay of inhibitory input relative to excitatory input originates from an extra synapse in the circuit shaping inhibitory input. Another common motif is push-pull or “crossover” inhibition, in which increases (decreases) in excitatory input occur together with decreases (increases) in inhibitory input. Primate On midget ganglion cells receive primarily feedforward inhibition and On parasol cells receive primarily crossover inhibition; this difference provides an opportunity to study how each motif shapes the light responses of cell types that play a key role in visual perception. For full-field stimuli, feedforward inhibition abbreviated and attenuated responses of On midget cells, while crossover inhibition, though plentiful, had surprisingly little impact on the responses of On parasol cells. Spatially structured stimuli, however, could cause excitatory and inhibitory inputs to On parasol cells to increase together, adopting a temporal relation very much like that for feedforward inhibition. In this case, inhibitory inputs substantially abbreviated a cell’s spike output. Thus inhibitory input shapes the temporal stimulus selectivity of both midget and parasol ganglion cells, but its impact on responses of parasol cells depends strongly on the spatial structure of the light inputs. PMID:23575830

Cafaro, Jon; Rieke, Fred

2013-01-01

212

Hydrogen sulfide inhibits amyloid formation.  

PubMed

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 ?-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of ?-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

Rosario-Alomar, Manuel F; Quiñones-Ruiz, Tatiana; Kurouski, Dmitry; Sereda, Valentin; Ferreira, Eduardo B; Jesús-Kim, Lorraine De; Hernández-Rivera, Samuel; Zagorevski, Dmitri V; López-Garriga, Juan; Lednev, Igor K

2015-01-29

213

Neurophysiology of Dystonia: The Role of Inhibition  

PubMed Central

The pathophysiology of dystonia has been best studied in patients with focal hand dystonia. A loss of inhibitory function has been demonstrated at spinal, brainstem and cortical levels. Many cortical circuits seem to be involved. One consequence of the loss of inhibition is a failure of surround inhibition, and this appears to directly lead to overflow and unwanted muscle spasms. There are mild sensory abnormalities and deficits in sensorimotor integration; these also might be explained by a loss of inhibition. Increasing inhibition may be therapeutic. A possible hypothesis is that there is a genetic loss of inhibitory interneurons in dystonia and that this deficit is a substrate on which other factors can act to produce dystonia. PMID:20817092

Hallett, Mark

2010-01-01

214

Toxicants inhibiting anaerobic digestion: a review.  

PubMed

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. PMID:25457225

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

2014-12-01

215

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...

216

Inhibition of PMN leukocytes chemotaxis by thalidomide  

Microsoft Academic Search

The effects of thalidomide on chemotaxis of normal human peripheral blood PMN leukocytes have been studied in vitro. The chemotaxis factor was generated by interacting normal human serum with bovine gamma globulin-antibovine-gamma globulin immune complexes. At concentrations of 1, 10, and 100 µg\\/ml, thalidomide failed to inhibit the chemotactic factor. At the same concentrations, erythromycin caused a marked inhibition of

Michel Faure; Jean Thivolet; Martine Gaucherand

1980-01-01

217

Matrix metalloproteinase inhibition by green tea catechins  

Microsoft Academic Search

We have investigated the effects of different biologically active components from natural products, including green tea polyphenols (GTP), resveratrol, genistein and organosulfur compounds from garlic, on matrix metalloproteinase (MMP)-2, MMP-9 and MMP-12 activities. GTP caused the strongest inhibition of the three enzymes, as measured by fluorescence assays using gelatin or elastin as substrates. The inhibition of MMP-2 and MMP-9 caused

Michel Demeule; Mathieu Brossard; Martine Pagé; Denis Gingras; Richard Béliveau

2000-01-01

218

Chemical Defoliation and Regrowth Inhibition in Cotton.  

E-print Network

icals such as parasorbic acid and unsaturated lactones have been shown to have similar effects. Several workers (23, 27) have suggested the possibility that a special inhibiting sub- stance is produced in some way, from or by auxin, in the lat- erals... that, in cotton, other factors may be more directly concerned in axill- ary bud suppression. The results with coumarin, an unsaturated lactone, and other inhibiting materials, although far from conclusive, favor the hypothesis that an inhibitor...

Lane, H. C.; Truchelut, G. B.; Hall, W. C.

1953-01-01

219

Seed extracts inhibiting protein synthesis in vitro.  

PubMed Central

Of 33 seed extracts examined, 12 inhibited protein synthesis in a rabbit reticulocyte lysate. This activity seems to be due to a protein, since (i) it was recovered with the (NH4)2SO4 precipitate, (ii) it was retained by dialysis membranes, and (iii) in all cases but one was destroyed by boiling. Only the extracts from the seeds of Adenia digitata and, to a lower extent, of Euonymus europaeus inhibited protein synthesis in intact cells. PMID:7378060

Gasperi-Campani, A; Barbieri, L; Morelli, P; Stirpe, F

1980-01-01

220

Inhibited solid propellant composition containing beryllium hydride  

NASA Technical Reports Server (NTRS)

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.

Thompson, W. W. (inventor)

1978-01-01

221

Grape seed extracts inhibit platelet aggregation by inhibiting protein tyrosine phosphatase.  

PubMed

Platelets play an important role in various thrombotic diseases, including myocardial infarction. Because red wine consumption is inversely associated with death due to ischemic heart diseases, the effects of grape components on platelet function have been extensively investigated. Grape seed extracts (GSEs) reportedly inhibit platelet aggregation; however, the underlying mechanism has not been elucidated. We discovered that GSEs inhibit platelet aggregation induced by collagen and thrombin-receptor agonist peptide and increase basal levels of tyrosine phosphorylation, which was also observed in the presence of a protein tyrosine phosphatase (PTP) inhibitor. An in vitro phosphatase assay indicated that GSE dose dependently inhibited PTP-1B and Src homology 2 domain-containing phosphatase-1 activity, which positively regulates platelet aggregation. We propose that GSEs inhibit platelet aggregation by inhibiting tyrosine phosphatase activity. Moreover, we showed that GSE ingestion inhibited platelet aggregation in mice without enhancing tail bleeding, implying that GSE supplementation might be beneficial to prevention of thrombotic diseases. PMID:23478570

Jin, Joseph Wuxun; Inoue, Osamu; Suzuki-Inoue, Katsue; Nishikawa, Go; Kawakami, Yoshinori; Hisamoto, Masashi; Okuda, Tohru; Ozaki, Yukio

2014-04-01

222

Activin inhibits telomerase activity in cancer  

SciTech Connect

Activin is a pleiotropic cytokine with broad tissue distributions. Recent studies demonstrate that activin-A inhibits cancer cell proliferation with unknown mechanisms. In this report, we demonstrate that recombinant activin-A induces telomerase inhibition in cancer cells. In breast and cervical cancer cells, activin-A resulted in telomerase activity in a concentration-dependent manner. Significant inhibition was observed at 10 ng/ml of activin-A, with a near complete inhibition at 80 ng/ml. Consistently, activin-A induced repression of the telomerase reverse transcriptase (hTERT) gene, with the hTERT gene to be suppressed by 60-80% within 24 h. In addition, activin-A induced a concomitant increase in Smad3 signaling and decrease of the hTERT gene promoter activity in a concentration-dependent fashion. These data suggest that activin-A triggered telomerase inhibition by down-regulating hTERT gene expression is involved in activin-A-induced inhibition of cancer cell proliferation.

Katik, Indzi; Mackenzie-Kludas, Charley; Nicholls, Craig [Department of Immunology, Monash University, Melbourne (Australia)] [Department of Immunology, Monash University, Melbourne (Australia); Jiang, Fang-Xu [Centre for Diabetes Research, Western Australian Institute for Medical Research and The University of Western Australia, Perth (Australia)] [Centre for Diabetes Research, Western Australian Institute for Medical Research and The University of Western Australia, Perth (Australia); Zhou, Shufeng [School of Health Sciences, RMIT University, Melbourne (Australia)] [School of Health Sciences, RMIT University, Melbourne (Australia); Li, He [Department of Immunology, Monash University, Melbourne (Australia)] [Department of Immunology, Monash University, Melbourne (Australia); Liu, Jun-Ping, E-mail: jun-ping.liu@med.monash.edu.au [Department of Immunology, Monash University, Melbourne (Australia)] [Department of Immunology, Monash University, Melbourne (Australia)

2009-11-27

223

Allosteric antibody inhibition of human hepsin protease.  

PubMed

Hepsin is a type II transmembrane serine protease that is expressed in several human tissues. Overexpression of hepsin has been found to correlate with tumour progression and metastasis, which is so far best studied for prostate cancer, where more than 90% of such tumours show this characteristic. To enable improved future patient treatment, we have developed a monoclonal humanized antibody that selectively inhibits human hepsin and does not inhibit other related proteases. We found that our antibody, hH35, potently inhibits hepsin enzymatic activity at nanomolar concentrations. Kinetic characterization revealed non-linear, slow, tight-binding inhibition. This correlates with the crystal structure we obtained for the human hepsin-hH35 antibody Fab fragment complex, which showed that the antibody binds hepsin around ?3-helix, located far from the active centre. The unique allosteric mode of inhibition of hH35 is distinct from the recently described HGFA (hepatocyte growth factor activator) allosteric antibody inhibition. We further explain how a small change in the antibody design induces dramatic structural rearrangements in the hepsin antigen upon binding, leading to complete enzyme inactivation. PMID:22132769

Koschubs, Tobias; Dengl, Stefan; Dürr, Harald; Kaluza, Klaus; Georges, Guy; Hartl, Christiane; Jennewein, Stefan; Lanzendörfer, Martin; Auer, Johannes; Stern, Alvin; Huang, Kuo-Sen; Packman, Kathryn; Gubler, Ueli; Kostrewa, Dirk; Ries, Stefan; Hansen, Silke; Kohnert, Ulrich; Cramer, Patrick; Mundigl, Olaf

2012-03-15

224

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

PubMed Central

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

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

2001-01-01

225

Detecting age differences in inhibition processes with a test of perceptual and motor inhibition  

PubMed Central

We asked whether different forms of inhibition are altered differently by aging using a Motor and Perceptual Inhibition Test (MAPIT) based on Nassauer and Halperin (Nassauer & Halperin, 2003). Ninety-eight individuals participating in studies of balance and attention were separated into younger (mean age 25 years) and older participants (mean age 73). Older participants showed less Perceptual and Motor Inhibition than younger participant with moderation of this effect by gender. The two scores were uncorrelated in the young but significantly correlated in the older group. Overall, the MAPIT appeared to yield reliable measures of two aspects of inhibition that demonstrate a differential impact of age. PMID:21424956

Jennings, J. Richard; Mendelson, David N.; Redfern, Mark S.; Nebes, Robert D

2010-01-01

226

Characterization of acetylcholinesterase-inhibition by itopride.  

PubMed

Itopride is a gastroprokinetic benzamide derivative. This agent inhibited both electric eel acetylcholinesterase (AChE) and horse serum butyrylcholinesterase (BuChE). The IC50 of itopride with AChE (2.04 +/- 0.27 microM) was, however, 100-fold less than that with BuChE, whereas in the case of neostigmine with AChE (11.3 +/- 3.4 nM), it was 10-fold less. The recovery of AChE activity inhibited by 10(-7) M neostigmine was partial, but that inhibited by up to 3 x 10(-5) M itopride was complete when the reaction mixture was subjected to ultrafiltration. Double reciprocal plots of the experimental data showed that both Km and Vmax were affected by itopride, suggesting that the inhibition is a "mixed" type, although primarily being an uncompetitive one. The inhibitory effect of itopride on cholinesterase (ChE) activity in guinea pig gastrointestine was much weaker than that on pure AChE. However, in the presence of a low dose of diisopropyl fluorophosphate, just enough to inhibit BuChE but not AChE, the IC50s of itopride against ChE activities were found to be about 0.5 microM. In conclusion, itopride exerts reversible and a "mixed" type of inhibition preferably against AChE. The IC50 of itopride for electric eel and guinea pig gastrointestinal AChE inhibition was 200 times and 50 times as large as that of neostigmine, respectively. PMID:7869618

Iwanaga, Y; Kimura, T; Miyashita, N; Morikawa, K; Nagata, O; Itoh, Z; Kondo, Y

1994-11-01

227

Response Inhibition in Motor Conversion Disorder  

PubMed Central

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

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

2014-01-01

228

Dendroarchitecture and lateral inhibition in thalamic barreloids.  

PubMed

Thalamic cells that relay vibrissa information to barrel cortex are clustered within whisker-related modules termed barreloids. Each barreloid receives input from one principal whisker and inhibitory inputs from reticular thalamic neurons with receptive fields that correspond to that same whisker. Although the proximal dendrites of relay cells are confined to their home barreloid, distal dendrites often extend into surrounding barreloids representing adjacent whiskers on the mystacial pad. It was proposed that this arrangement provides a substrate for a mechanism of lateral inhibition that operates remotely on extrabarreloid dendrites. In the present study, we identified adjacent whiskers that suppressed activity below background levels in barreloid cells, and we used a double-labeling protocol to relate the efficacy of inhibition to the dendroarchitecture of the cells. Significant suppression of background discharges was produced by 92% of adjacent whiskers within rows, by 48% of adjacent whiskers within arcs, but was never observed after deflection of nonadjacent whiskers. The magnitude of lateral inhibition increases linearly as the cumulated length of dendrites increases in the barreloid representing an adjacent whisker (R2 = 0.86; p < 0.0001). As distance between cell bodies and the border of an adjacent barreloid increases, dendritic length in that adjacent barreloid diminishes and so does inhibition. Considering time differences between the arrival of principal and adjacent whisker inputs in barreloids, our data suggest that inhibition operating distally on dendrites acts as a spatial filter that primarily suppresses adjacent whisker inputs and so contributes to enhance edge detection. PMID:15240801

Lavallée, Philippe; Deschênes, Martin

2004-07-01

229

ROCK Inhibition Activates MCF-7 Cells  

PubMed Central

Dormant carcinoma cancer cells showing epithelial characteristics can be activated to dissipate into the surrounding tissue or organs through epithelial-mesenchymal transition (EMT). However, the molecular details underlying the activation of dormant cancer cells have been less explored. In this study, we examined the molecular pathway to activate dormant breast cancer cells. Rho-associated kinase (ROCK) inhibition disrupted cell junction, promoted cell proliferation and migration / invasion in both two-dimensional and three-dimensional substrates. The disintegration of cell junction upon ROCK inhibition, coupled with the loss of E-cadherin and b-catenin from the cell membrane, was associated with the activation of Rac1 upon ROCK inhibition. Migration / invasion also increased upon ROCK inhibition. However, the activation of MCF-7 cells upon ROCK inhibition was not associated with the up-regulation of typical EMT markers, such as snail and slug. Based on these results, we suggest the potential risk for dormant cancer cells to dissipate through non-typical EMT when ROCK activity is down-regulated. PMID:24523903

Yang, Seungwon; Kim, Hyun-Man

2014-01-01

230

IGF-1 receptor antagonism inhibits autophagy  

PubMed Central

Inhibition of the insulin/insulin-like growth factor signalling pathway increases lifespan and protects against neurodegeneration in model organisms, and has been considered as a potential therapeutic target. This pathway is upstream of mTORC1, a negative regulator of autophagy. Thus, we expected autophagy to be activated by insulin-like growth factor-1 (IGF-1) inhibition, which could account for many of its beneficial effects. Paradoxically, we found that IGF-1 inhibition attenuates autophagosome formation. The reduced amount of autophagosomes present in IGF-1R depleted cells can be, at least in part, explained by a reduced formation of autophagosomal precursors at the plasma membrane. In particular, IGF-1R depletion inhibits mTORC2, which, in turn, reduces the activity of protein kinase C (PKC?/?). This perturbs the actin cytoskeleton dynamics and decreases the rate of clathrin-dependent endocytosis, which impacts autophagosome precursor formation. Finally, with important implications for human diseases, we demonstrate that pharmacological inhibition of the IGF-1R signalling cascade reduces autophagy also in zebrafish and mice models. The novel link we describe here has important consequences for the interpretation of genetic experiments in mammalian systems and for evaluating the potential of targeting the IGF-1R receptor or modulating its signalling through the downstream pathway for therapeutic purposes under clinically relevant conditions, such as neurodegenerative diseases, where autophagy stimulation is considered beneficial. PMID:23804751

Renna, Maurizio; Bento, Carla F.; Fleming, Angeleen; Menzies, Fiona M.; Siddiqi, Farah H.; Ravikumar, Brinda; Puri, Claudia; Garcia-Arencibia, Moises; Sadiq, Oana; Corrochano, Silvia; Carter, Sarah; Brown, Steve D.M.; Acevedo-Arozena, Abraham; Rubinsztein, David C.

2013-01-01

231

A Fusion-Inhibiting Peptide against Rift Valley Fever Virus Inhibits Multiple, Diverse Viruses  

E-print Network

A Fusion-Inhibiting Peptide against Rift Valley Fever Virus Inhibits Multiple, Diverse Viruses of America Abstract For enveloped viruses, fusion of the viral envelope with a cellular membrane is critical for a productive infection to occur. This fusion process is mediated by at least three classes of fusion proteins

232

Inhibition in Language Switching: What Is Inhibited when Switching between Languages in Naming Tasks?  

ERIC Educational Resources Information Center

When people switch between languages, inhibition of currently irrelevant languages is assumed to occur. The authors examined inhibition of irrelevant languages with a cued language-switching paradigm. A cue indicated in which of 3 languages (German, English, or French) a visual stimulus was to be named. In 2 experiments, the authors found that…

Philipp, Andrea M.; Koch, Iring

2009-01-01

233

Inhibition of Inhibition in Visual Cortex: The Logic of Connections Between Molecularly Distinct Interneurons  

PubMed Central

Cortical inhibitory neurons contact each other to form a network of inhibitory synaptic connections. Our knowledge of the connectivity pattern underlying this inhibitory network is, however, still incomplete. Here we discover a simple and complementary interaction scheme between three large molecularly distinct interneuron populations in mouse visual cortex: Parvalbumin expressing interneurons strongly inhibit one another but, surprisingly, provide little inhibition to other populations. In contrast, somatostatin expressing interneurons avoid inhibiting one another, yet strongly inhibit all other populations. Finally, vasoactive intestinal peptide expressing interneurons preferentially inhibit somatostatin interneurons. This scheme occurs in supra- and infra-granular layers, suggesting that inhibitory networks operate similarly at the input and output of visual cortex. Thus, as the specificity of connections between excitatory neurons forms the basis for the cortical canonical circuit, the scheme described here outlines a standard connectivity pattern among cortical inhibitory neurons. PMID:23817549

Pfeffer, Carsten K.; Xue, Mingshan; He, Miao; Huang, Z. Josh; Scanziani, Massimo

2013-01-01

234

Cl-IB-MECA inhibits human erythropoiesis.  

PubMed

Candidate drugs are being sought for the suppression of human erythropoiesis. Cl-IB-MECA [2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide] is a derivative of adenosine that inhibits the growth of leukaemic cell lines. To determine the effects of Cl-IB-MECA upon erythropoiesis, studies were performed by using an ex vivo culture system of primary human CD34+ cells. Cl-IB-MECA suppressed erythroblast growth and maturation at doses >/=50 mumol/l through a mechanism of cell cycle inhibition and accumulation of cells in the G1/G0 phase. These findings demonstrate that Cl-IB-MECA inhibits human erythropoiesis, and suggest that further consideration of this drug is warranted for patients with erythrocytosis or polycythemia syndromes. PMID:17408462

Bhanu, Natarajan V; Aerbajinai, Wulin; Gantt, Nicole M; Jackson, Edwin K; Goh, Sung-Ho; Terry Lee, Y; Miller, Jeffery L

2007-05-01

235

Inhibition of microbial cholesterol oxidases by dimethylmorpholines.  

PubMed

Cholesterol oxidase is a potentially important enzyme in steroid transformations, catalysing the conversion of 3-hydroxy-5-ene steroids to 3-keto-4-ene derivatives via a 3-keto-5-ene intermediate. Morpholine derivatives, especially fenpropimorph and tridemorph, were found to block selectively the isomerisation activity of cholesterol oxidases isolated from Nocardia erythropolis, Streptomyces sp., Pseudomonas testosteroni and Schizophyllum commune. These enzymes differ strongly in physical characteristics and catalytic behaviour. The effectiveness of the inhibitors varied with the cholesterol oxidase tested. Fenpropimorph was most effective with each of the 4 enzymes, 50 mg/l inhibiting about 50% of the enzyme activity. Inhibition was instantaneous and followed a reversible competitive mechanism in Streptomyces sp. and a reversible non-competitive mechanism in Nocardia erythropolis and Schizophyllum commune. An irreversible type of inhibition was observed for P. testosteroni cholesterol oxidase. PMID:2308321

Hesselink, P G; Kerkenaar, A; Witholt, B

1990-01-01

236

Inhibition of medulloblastoma cell invasion by Slit  

PubMed Central

Invasion of brain tumor cells has made primary malignant brain neoplasms among the most recalcitrant to therapeutic strategies. We tested whether the secreted protein Slit2, which guides the projection of axons and developing neurons, could modulate brain tumor cell invasion. Slit2 inhibited the invasion of medulloblastoma cells in a variety of in vitro models. The effect of Slit2 was inhibited by the Robo ectodomain. Time-lapse videomicroscopy indicated that Slit2 reduced medulloblastoma invasion rate without affecting cell direction or proliferation. Both medulloblastoma and glioma tumors express Robo1 and Slit2, but only medulloblastoma invasion is inhibited by recombinant Slit2 protein. Downregulation of activated Cdc42 may contribute to this differential response. Our findings reinforce the concept that neurodevelopmental cues such as Slit2 may provide insights into brain tumor invasion. PMID:16636676

Werbowetski-Ogilvie, TE; Sadr, M Seyed; Jabado, N; Angers-Loustau, A; Agar, NYR; Wu, J; Bjerkvig, R; Antel, JP; Faury, D; Rao, Y; Maestro, RF Del

2007-01-01

237

Surface modification for aluminium pigment inhibition.  

PubMed

This review concerns surface treatment of aluminium pigments for use in water borne coatings. Aluminium pigments are commonly used in coatings to give a silvery and shiny lustre to the substrate. Such paints and inks have traditionally been solvent borne, since aluminium pigment particles react with water. For environmental and health reasons solvent borne coatings are being replaced by water borne and the aluminium pigments then need to be surface modified in order to stand exposure to water. This process is called inhibition and both organic and inorganic substances are used as inhibiting agents. The organic inhibiting agents range from low molecular weight substances, such as phenols and aromatic acids, via surfactants, in particular alkyl phosphates and other anionic amphiphiles, to high molecular weight compounds, such as polyelectrolytes. A common denominator for them all is that they contain a functional group that interacts specifically with aluminium at the surface. A particularly strong interaction is obtained if the inhibiting agent contains functional groups that form chelating complex with surface Al(III). Encapsulation of the pigment can be made by in situ polymerization at the surface of the pigment and a recent approach is to have the polymerization occur within a double layer of adsorbed surfactant. The inorganic route is dominated by coating with silica, and recent progress has been made using an alkoxide, such as tetraethoxysilane as silica precursor. Such silica coated aluminium pigments are comparable in performance to chromate inhibited pigments and thus offer a possible heavy metal-free alternative. There are obvious connections between surface modifications made to prevent the pigment to react with water and inhibition of corrosion of macroscopic aluminium surfaces. PMID:17239333

Karlsson, Philip; Palmqvist, Anders E C; Holmberg, Krister

2006-12-21

238

Enzyme kinetics for clinically relevant CYP inhibition.  

PubMed

In vitro cytochrome P450 (CYP)-associated metabolic studies have been considered cost-effective for predicting the potential clinical drug-drug interactions (DDIs), one of the major attritions in drug development. The breakthroughs during the past decade in understanding the biochemistry of CYP-mediated biotransformation and molecular biology of CYP gene regulation in humans have provided the scientific bases for such endeavors in early drug development. In this review, the enzyme kinetics of CYP inhibitions is described, with the primary focus on the ones proven with clinical relevance, namely the competitive inhibition and mechanism-based inactivation (MBI). Competitive CYP inhibition, the most often detected reversible inhibition, is well understood and has been studied extensively both in vitro and in clinical setting. Recently, MBI has received increasing attention. It has been recognized that MBI could occur more often than anticipated, due in part to the redox cycling-allied enzymatic action of CYPs. As commonly as an irreversible inhibition, MBI would inactivate the target proteins, and thus would be generally considered of high potential for causing clinical DDI. Moreover, the reversible inhibitions other than the competitive, namely noncompetitive, uncompetitive and mixed, were also documented for the important drug-metabolizing CYP members, particularly CYP1A2 and CYP2C9. Finally, the unusual kinetic interactions, which did not follow the Michaelis-Menten (M-M) kinetics, were detected in vitro for the majority of drug-metabolizing CYP members, and manifested for CYP3A4. However, the clinical relevance of the interactions involving the unusual CYP kinetics has not yet been fully understood. Nonetheless, the reversibility and inhibitory potency should be considered as the major determinants of the clinical relevance, particularly in combination with the therapeutic exposure levels. With rapid expansion of knowledge and technology, the evaluation of the clinically relevant CYP-associated DDIs in vitro is not only desirable but also achievable. PMID:15975042

Zhang, Zhi-Yi; Wong, Y Nancy

2005-06-01

239

Bacterial contact-dependent growth inhibition (CDI)  

PubMed Central

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

Ruhe, Zachary C.; Low, David A.; Hayes, Christopher S.

2013-01-01

240

Adaptive regulation of sparseness by feedforward inhibition.  

PubMed

In the mushroom body of insects, odors are represented by very few spikes in a small number of neurons, a highly efficient strategy known as sparse coding. Physiological studies of these neurons have shown that sparseness is maintained across thousand-fold changes in odor concentration. Using a realistic computational model, we propose that sparseness in the olfactory system is regulated by adaptive feedforward inhibition. When odor concentration changes, feedforward inhibition modulates the duration of the temporal window over which the mushroom body neurons may integrate excitatory presynaptic input. This simple adaptive mechanism could maintain the sparseness of sensory representations across wide ranges of stimulus conditions. PMID:17660812

Assisi, Collins; Stopfer, Mark; Laurent, Gilles; Bazhenov, Maxim

2007-09-01

241

Multivalent helix mimetics for PPI-inhibition.  

PubMed

The exploitation of multivalent ligands for the inhibition of protein-protein interactions has not yet been explored as a supramolecular design strategy. This is despite the fact that protein-protein interactions typically occur within the context of multi-protein complexes and frequently exploit avidity effects or co-operative binding interactions to achieve high affinity interactions. In this paper we describe preliminary studies on the use of a multivalent N-alkylated aromatic oligoamide helix mimetic for inhibition of p53/hDM2 and establish that protein dimerisation is promoted, rather than enhanced binding resulting from a higher effective concentration of the ligand. PMID:25408290

Barnard, Anna; Miles, Jennifer A; Burslem, George M; Barker, Amy M; Wilson, Andrew J

2015-01-01

242

Inhibition of diamine oxidase activity by metronidazole.  

PubMed

Metronidazole was found to be a non-competitive inhibitor of man, rabbit and rat intestinal diamine oxidases with an inhibition constant value of approximately 10(-4) M. The purified bovine serum amine oxidase was not inhibited, whereas the purified swine kidney enzyme gave similar results. These findings suggest that metronidazole and similar compounds, used as antibacterial and antiprotozoal drugs, should be given under careful control, especially when administered for long times, because a decrease of intestinal diamine oxidase activity was proven to be a risk factor for several pathologies of this organ. PMID:7626074

Befani, O; Shiozaki, T S; Turini, P; Gerosa, P; Mondovi, B

1995-07-17

243

Bacterial contact-dependent growth inhibition.  

PubMed

Bacteria cooperate to form multicellular communities and compete against one another for environmental resources. Here, we review recent advances in the 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 protein pairs appear to be exchanged between cdi loci and are often associated with other toxin-delivery systems in diverse bacterial species. CDI also appears to facilitate cooperative behavior between kin, suggesting that these systems may have other roles beyond competition. PMID:23473845

Ruhe, Zachary C; Low, David A; Hayes, Christopher S

2013-05-01

244

Inhibition of STIM1 phosphorylation underlies resveratrol-induced inhibition of store-operated calcium entry.  

PubMed

Resveratrol, a natural phytoalexin that shows health-promoting benefits, is an inhibitor of store-operated calcium entry (SOCE). Knowledge of the molecular mechanism underlying this inhibition is required for the proper design of therapies that include resveratrol or related stilbenoids, but remains largely unknown. To unravel this mechanism, using HEK293 cells as a model, we found that resveratrol inhibited the ERK1/2 activation triggered by Ca²? store depletion. As a consequence, resveratrol inhibited STIM1 phosphorylation at residues Ser575, Ser608, and Ser621. Because this phosphorylation regulates the dissociation of STIM1 from the microtubule plus-end binding protein EB1 under store depletion conditions, resveratrol inhibited STIM1-EB1 dissociation. This inhibition had downstream effects such as inhibition of STIM1 multimerization in response to store depletion, and a significant impairment in the binding of STIM1 to ORAI1. Although additional targets for resveratrol in the molecular mechanism that governs SOCE cannot be discarded, the present results demonstrate that ERK1/2 pathway is a major target for resveratrol, and that the impairment of its activation produces a significant inhibition of SOCE. PMID:24095720

Casas-Rua, Vanessa; Alvarez, Ignacio S; Pozo-Guisado, Eulalia; Martín-Romero, Francisco Javier

2013-12-01

245

Recombinant human mullerian inhibiting substance inhibits human ocular melanoma cell lines in vitro and in vivo.  

PubMed

Since Mullerian Inhibiting Substance (MIS) causes regression of the Mullerian duct, the anlagen of the uterus, vagina, and fallopian tube, we expected and have previously observed that purified recombinant human MIS causes regression of gynecological tumors. However, recent experiments indicating that neural crest derivatives might be responsive to MIS prompted study of a group of human ocular melanoma cell lines in 4 in vitro inhibition assays, and a subrenal capsule assay in vivo. Ocular melanoma cell lines that grew well in a respective assay were studied with MIS to determine whether this biological modifier could inhibit growth. Three human ocular melanomas, OM431 (P less than 0.01), OM467 (P less than 0.02), and OM482 (P less than 0.03), were growth-inhibited by highly purified human recombinant MIS in soft agarose. A dose-dependent tumor inhibition was noted when OM431 cells were incubated with MIS in a liquid colony inhibition assay (P less than 0.05). In addition, OM467 was inhibited (P less than 0.05) by MIS in a multicellular tumor spheroid assay. Cell cycle analysis indicated that OM431 cells were inhibited in monolayer by MIS while in G1. At 100-fold lower serum concentrations than required in the media of in vitro assays, MIS delivered via i.p. osmotic pumps inhibited (P less than 0.05) in vivo the growth of OM431 implanted beneath the renal capsule of nude and CD-1 irradiated mice when compared to mice given implants of pumps containing no MIS. The responsiveness of ocular melanoma to MIS broadens the spectrum of tumors that might be treated with MIS and suggests further investigation of other neural crest tumors. PMID:1531323

Parry, R L; Chin, T W; Epstein, J; Hudson, P L; Powell, D M; Donahoe, P K

1992-03-01

246

Inhibition of neutrophil oxidative metabolism by nimesulide  

Microsoft Academic Search

Oxygen derived free radical release from activated neutrophils may be in part responsible of tissue damage in the acute phase of inflammation. We have shown that the methane sulfonanilide antiinflammatory agent nimesulide inhibits the respiratory burst of phagocytosing neutrophils without affecting their phagocytic or chemotactic responsiveness. In fact, chemiluminescence and superoxide anion generation by polymorphonuclear leukocytes (PMN) stimulated with zymosan

F. Capsoni; E. Venegoni; F. Minonzio; A. M. Ongari; V. Maresca; C. Zanussi

1987-01-01

247

Corrosion Inhibition of Steel by Bacteria  

Microsoft Academic Search

Mild steel was exposed to Pseudomonas sp. S9 or Serratia marcescens in synthetic seawater. An increase in corrosion resistance over that i natural seawater was monitored by electrochemical techniques. Biological analyses were performed to characterize the system. The inhibition effect also was observed when mild steel was coated with bacteria and then immersed in synthetic seawater. When specimens coated with

G. Hernandez; V. Kucera; D. Thierry; M. Hermansson; A. Pedersen

1994-01-01

248

Molybdate in corrosion inhibition - A review  

Microsoft Academic Search

It has been nearly 50 y since molybdate compounds were first identified and put to practical use as corrosion inhibitors. Molybdates are now among the most broadly applied inhibitors, chiefly because of their efficacy toward both ferrous and nonferrous metals and their very low order of toxicity. This review summarizes fundamental and applied studies dealing with molybdates in corrosion inhibition

M. S. Vukasovich; J. P. G. Farr

1986-01-01

249

Motivational Influences on Response Inhibition Measures  

ERIC Educational Resources Information Center

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…

Leotti, Lauren A.; Wager, Tor D.

2010-01-01

250

Product Inhibition in Native-State Proteolysis  

PubMed Central

The proteolysis kinetics of intact proteins by nonspecific proteases provides valuable information on transient partial unfolding of proteins under native conditions. Native-state proteolysis is an approach to utilize the proteolysis kinetics to assess the energetics of partial unfolding in a quantitative manner. In native-state proteolysis, folded proteins are incubated with nonspecific proteases, and the rate of proteolysis is determined from the disappearance of the intact protein. We report here that proteolysis of intact proteins by nonspecific proteases, thermolysin and subtilisin deviates from first-order kinetics. First-order kinetics has been assumed for the analysis of native-state proteolysis. By analyzing the kinetics of proteolysis with varying concentrations of substrate proteins and also with cleavage products, we found that the deviation from first-order kinetics results from product inhibition. A kinetic model including competitive product inhibition agrees well with the proteolysis time course and allows us to determine the uninhibited rate constant for proteolysis as well as the apparent inhibition constant. Our finding suggests that the likelihood of product inhibition must be considered for quantitative assessment of proteolysis kinetics. PMID:25360755

Kasper, Joseph R.; Andrews, Elizabeth C.; Park, Chiwook

2014-01-01

251

Temporal Preparation, Response Inhibition and Impulsivity  

ERIC Educational Resources Information Center

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…

Correa, Angel; Trivino, Monica; Perez-Duenas, Carolina; Acosta, Alberto; Lupianez, Juan

2010-01-01

252

Kasugamycin inhibition of bacterial sporulation. Final report  

SciTech Connect

Kasugamycin has been observed to specifically inhibit the sporulation process in Bacillus subtilis at a level below that showing any effect on vegetative growth. A new locus, Ksg-D, has been identified as a locus responsible of Ksg resistant sporulation. Ksg-D may affect the cellular permeability barrier to the drug. (ACR)

Bott, K.F.

1980-01-01

253

Plant pathology Growth inhibition of Agaricus bisporus  

E-print Network

Plant pathology Growth inhibition of Agaricus bisporus and associated thermophilic species Agaricus bisporus and 3 isolates of thermophilic fungi active in mushroom composting. At concentrations compost I fungicide residue I Agaricus bisporus I Torula thermophila I Humicola grisea var ther- moidea

Paris-Sud XI, Université de

254

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...

255

Theobromine inhibits sensory nerve activation and cough  

Microsoft Academic Search

Cough is a common and protective reflex, but persistent coughing is debilitating and impairs quality of life. Antitussive treatment using opioids is limited by unacceptable side effects, and there is a great need for more effective remedies. The present study demonstrates that theobromine, a methylxanthine derivative present in cocoa, effectively inhibits citric acid- induced cough in guinea-pigs in vivo. Furthermore,

Omar S. Usmani; Maria G. Belvisi; Hema J. Patel; Natascia Crispino; Mark A. Birrell; Márta Korbonits; Peter J. Barnes

2004-01-01

256

Matrix metalloproteinase inhibition by green tea catechins.  

PubMed

We have investigated the effects of different biologically active components from natural products, including green tea polyphenols (GTP), resveratrol, genistein and organosulfur compounds from garlic, on matrix metalloproteinase (MMP)-2, MMP-9 and MMP-12 activities. GTP caused the strongest inhibition of the three enzymes, as measured by fluorescence assays using gelatin or elastin as substrates. The inhibition of MMP-2 and MMP-9 caused by GTP was confirmed by gelatin zymography and was observed for MMPs associated with both various rat tissues and human brain tumors (glioblastoma and pituitary tumors). The activities of MMPs were also measured in the presence of various catechins isolated from green tea including (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate(ECG), (-)-epigallocatechin (EGC), (-)-epicatechin (EC) and (+)-catechin (C). The most potent inhibitors of these activities, as measured by fluorescence and by gelatin or casein zymography, were EGCG and ECG. GTP and the different catechins had no effect on pancreatic elastase, suggesting that the effects of these molecules on MMP activities are specific. Furthermore, in vitro activation of proMMP-2 secreted from the glioblastomas cell line U-87 by the lectin concanavalin A was completely inhibited by GTP and specifically by EGCG. These results indicate that catechins from green tea inhibit MMP activities and proMMP-2 activation. PMID:10719174

Demeule, M; Brossard, M; Pagé, M; Gingras, D; Béliveau, R

2000-03-16

257

T-2 mycotoxin inhibits mitochondrial protein synthesis  

SciTech Connect

The authors investigated the effect of T-2 toxin on rat liver mitochondrial protein synthesis. Isolated rat liver mitochondria were supplemented with an S-100 supernatant from rat liver and an external ATP-generating system. An in-vitro assay employing cycloheximide, and inhibitor of cytoplasmic protein synthesis, and chloramphenicol, and inhibitor of mitochondrial protein synthesis, to distinguish mitochondrial protein synthesis from the cytoplasmic process. Amino acid incorporation into mitochondria was dependent on the concentration of mitochondria and was inhibited by chloramphenicol. The rate of uptake of tritium leucine into mitochondrial protein was unaffected by the addition of T-2 toxin and was not a rate-limiting step in incorporation. However, 0.02 micrograms/ml of T-2 toxin decreased the rate of protein synthesis inhibition correlated with the amount of T-2 toxin taken up by the mitochondria. While T-2 toxin is known to inhibit eukaryotic protein synthesis, this is the first time T-2 was shown to inhibit mitochondrial protein synthesis.

Pace, J.G.; Watts, M.R.; Canterbury, W.J.

1988-01-01

258

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...

259

Salinomycin, a polyether ionophoric antibiotic, inhibits adipogenesis  

SciTech Connect

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.

Szkudlarek-Mikho, Maria; Saunders, Rudel A. [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States)] [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States); Yap, Sook Fan [Faculty of Medicine and Health Sciences, Department of Pre-Clinical Sciences, University of Tunku Abdul Rahman (Malaysia)] [Faculty of Medicine and Health Sciences, Department of Pre-Clinical Sciences, University of Tunku Abdul Rahman (Malaysia); Ngeow, Yun Fong [Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia)] [Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Chin, Khew-Voon, E-mail: khew-voon.chin@utoledo.edu [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States)] [Department of Medicine, Biochemistry and Cancer Biology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH 43614 (United States)

2012-11-30

260

Illustrating Enzyme Inhibition Using Gibbs Energy Profiles  

ERIC Educational Resources Information Center

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…

Bearne, Stephen L.

2012-01-01

261

Notch Receptor Activation Inhibits Oligodendrocyte Differentiation  

Microsoft Academic Search

In this study, we show that oligodendrocyte differentiation is powerfully inhibited by activation of the Notch pathway. Oligodendrocytes and their precursors in the developing rat optic nerve express Notch1 receptors and, at the same time, retinal ganglion cells express Jagged1, a ligand of the Notch1 receptor, along their axons. Jagged1 expression is developmentally regulated, decreasing with a time course that

Songli Wang; Andrei D Sdrulla; Guy diSibio; Gay Bush; Donna Nofziger; Carol Hicks; Gerry Weinmaster; Ben A Barres

1998-01-01

262

Inhibition of planarian regeneration by melatonin  

Microsoft Academic Search

Melatonin, which is a substance produced by the pineal body in vertebrates, inhibited regeneration in the planarian Dugesia japonica japonica Ichikawa et Kawakatsu. When decapitated planarians were maintained in a 1 mmol dm-3 solution of melatonin, formation of the head was retarded; formation of the eyes, however, was not disturbed. Similarly in animals from which the tail was cut, regeneration

Yasuhiro Yoshizawa; Katsumi Wakabayashi; Takao Shinozawa

1991-01-01

263

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...

264

Inhibited interferon production after space flight  

NASA Technical Reports Server (NTRS)

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.

Sonnenfeld, G.; Gould, C. L.; Williams, J.; Mandel, A. D.

1988-01-01

265

Radiosensitizing hypoxic tumors through metabolic inhibition  

Microsoft Academic Search

Background and Objectives. The response of tumors to radiation therapy is dependent upon oxygen levels, and tumors with low oxygen levels (i.e., hypoxic tumors) are radioresistant. Over 60% of human breast tumors are severely hypoxic. Of the two methods to increase oxygen levels, inhibition of tumor cell oxygen consumption is theoretically a better method than increasing the oxygen supply. The

John L Chunta

2008-01-01

266

Breaking of Seed Dormancy by Catalase Inhibition  

Microsoft Academic Search

Germination of some dormant seeds is promoted by solutions of thiourea, sodium nitrite, and hydroxylamine salts. The promotions are accompanied by irreversible inhibition of catalase (EC 1.11.1.6) in extracts from the seeds. The seeds are also promoted in germination by catechol and pyrogallol solutions. These effects are recorded for lettuce (Lactuca sativa L. cv. Grand Rapids) and pigweed (Amaranthus albus

S. B. Hendricks; R. B. Taylorson

1975-01-01

267

Inhibition of denitrification by ultraviolet radiation  

NASA Astrophysics Data System (ADS)

It has been shown that UV-A (? = 320- 400 nm) and UV-B (? = 280 - 320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC # 17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps. fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation.

Mancinelli, R. L.; White, M. R.

268

Inhibition of photosynthesis by heavy metals  

Microsoft Academic Search

Inhibition of photosynthesis by heavy metals is well documented. In this review the results are compared between in vitro experiments on isolated systems (chloroplasts, enzymes ­.), experiments on excised leaves and intact plants and algae in vivo. In vitro experiments suggest potential sites of heavy metal interaction with photosynthesis at several levels of organisation, which are not necessarily confirmed in

H. Clijsters; F. Assche

1985-01-01

269

The Mechanism Underlying Inhibition of Saccadic Return  

ERIC Educational Resources Information Center

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…

Ludwig, Casimir J. H.; Farrell, Simon; Ellis, Lucy A.; Gilchrist, Iain D.

2009-01-01

270

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 the mechanism of metabolic interactions occurring during simultaneous exposures to the organic solvents chloroform and trichloroethylene (TCE). Visualization-based se...

271

Serine\\/threonine protein phosphatase inhibition enhances the effect of thymidylate synthase inhibition  

Microsoft Academic Search

Purpose The serine\\/threonine protein phosphatases 1 (PP1) and 2A (PP2A) are key enzymes in regulating entry into the cell cycle, mitosis and apoptosis. Inhibition of PP1 and PP2A is associated with enhanced S-phase entry culminating in G 2\\/M arrest and apoptotic cell death. Thymidylate synthase (TS) is a key regulatory enzyme in DNA synthesis, inhibition of which is often a

Jennette A. Sakoff; Ian J. Howitt; Stephen P. Ackland; Adam McCluskey

2004-01-01

272

Spatially Reciprocal Inhibition of Inhibition within a Stimulus Selection Network in the Avian Midbrain  

PubMed Central

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

Goddard, C. Alex; Mysore, Shreesh P.; Bryant, Astra S.; Huguenard, John R.; Knudsen, Eric I.

2014-01-01

273

Disinhibition is easier learned than inhibition. The effects of (dis)inhibition training on food intake.  

PubMed

Impulsivity seems to be a strong candidate when it comes to psychological factors leading to overeating and eventually to obesity (Guerrieri, Nederkoorn, & Jansen, 2008). The question is whether reversing the logic and strengthening an individual's inhibitory skills will be equally potent against overeating. In the current study the stop signal task was adjusted so that one group of female students (n=21) gradually got more trials in which they could practise inhibition (inhibition), whereas another group (n=20) gradually got more trials in which they had to react quickly, without having time to think or inhibit (impulsivity). A third group (n=20) did a neutral reading task (control). The participants in the impulsivity group had a significantly higher caloric intake during a subsequent taste test, whereas the inhibition group did not differ from the control group. Hence, the data support that impulsivity is a direct cause of overeating. However, the concept of inhibition training needs to be investigated further. Issues like the specificity of inhibition training (general vs. food specific) need to be addressed and used to optimise the training so that its effectiveness can be tested within clinical settings. PMID:22521403

Guerrieri, Ramona; Nederkoorn, Chantal; Jansen, Anita

2012-08-01

274

Human müllerian inhibiting substance inhibits tumor growth in vitro and in vivo.  

PubMed

Müllerian inhibiting substance (MIS) causes regression of the müllerian duct in the male fetus. Bovine MIS has been reported to inhibit the growth of some gynecological tumors. Recombinant human MIS (rhMIS) produced in transfected Chinese hamster ovary cells has been highly purified by immunoaffinity chromatography. The introduction of a salt wash prior to elution of MIS from the affinity column removes a growth-stimulating factor(s) derived from Chinese hamster ovary cells. This immunopurified rhMIS caused significant inhibition (34-59% survival) of A431 (a vulvar epidermoid carcinoma), HT-3 (a cervical carcinoma), HEC-1-A (an endometrial adenocarcinoma), NIH:OVCAR-3 (an ovarian adenocarcinoma), and OM431 (an ocular melanoma) human cell lines in colony inhibition assays. Two cell lines, Hep 3B (a hepatocellular carcinoma) and RT4 (a bladder transitional cell papilloma), were unresponsive to immunopurified rhMIS. Using an in vivo subrenal capsule assay in irradiated CD-1 mice, the growth of A431 and OM431 cells was inhibited by immunopurified rhMIS. We conclude that rhMIS inhibits the growth of certain tumor cell lines in vitro and in vivo. PMID:2009529

Chin, T W; Parry, R L; Donahoe, P K

1991-04-15

275

Aminoglycoside antibiotics inhibit protein biosynthesis and various ribozymes. Structural electrostatic  

E-print Network

Aminoglycoside antibiotics inhibit protein biosynthesis and various ribozymes. Structural electrostatic complementarity can explain the inhibition mechanism of the hammerhead ribozyme: positively binders [3]. The functional diversity of RNA is based on the complex three-dimensional folds it can adopt

Westhof, Eric

276

Pterocarpans and flavanones from Sophora flavescens displaying potent neuraminidase inhibition  

E-print Network

Pterocarpans and flavanones from Sophora flavescens displaying potent neuraminidase inhibition Revised 6 September 2008 Accepted 8 October 2008 Available online 11 October 2008 Keywords: Neuraminidase Sophora flavescens and screened for their ability to inhibit neuraminidase (an enzyme crucial

Lee, Keun Woo

277

Sulfur Dioxide Inhibition of Photosynthesis in Isolated Spinach Chloroplasts  

PubMed Central

Photosynthetic oxygen evolution by isolated spinach (Spinacia oleracea L.) chloroplasts approached complete inhibition in the presence of a 5 mm concentration of sulfur dioxide. A similar inhibition was observed in the presence of equimolar concentrations of bisulfite ions, suggesting a parallel mode of action. In contrast, an equimolar concentration of sulfite ions was markedly less inhibitory and sulfate ions caused negligible inhibition of apparent photosynthesis. The mode of action of sulfur dioxide and related sulfur anions in inhibiting photosynthesis was found to be essentially independent of direct hydrogen-ion effects. Supplements of inorganic pyrophosphate lessened the inhibition of oxygen evolution caused by sulfur dioxide and the sulfur anions. Sulfur dioxide and the sulfur anions were almost equally effective in inhibiting cyclic and noncyclic photophosphorylation in chloroplast suspensions. However, the extent of the inhibition of these photosynthetic reactions does not appear sufficient to account for the inhibition of photosynthetic oxygen evolution by sulfur dioxide. PMID:16659319

Silvius, John E.; Ingle, Morris; Baer, Charles H.

1975-01-01

278

Structural analysis of kasugamycin inhibition of translation  

PubMed Central

The prokaryotic ribosome is an important target of antibiotic action. We determined the X-ray structure of the aminoglycoside kasugamycin (Ksg) in complex with the Escherichia coli 70S ribosome at 3.5-Å resolution. The structure reveals that the drug binds within the messenger RNA channel of the 30S subunit between the universally conserved G926 and A794 nucleotides in 16S ribosomal RNA, which are sites of Ksg resistance. To our surprise, Ksg resistance mutations do not inhibit binding of the drug to the ribosome. The present structural and biochemical results indicate that inhibition by Ksg and Ksg resistance are closely linked to the structure of the mRNA at the junction of the peptidyl-tRNA and exit-tRNA sites (P and E sites). PMID:16998486

Schuwirth, Barbara S; Day, J Michael; Hau, Cathy W; Janssen, Gary R; Dahlberg, Albert E; Cate, Jamie H Doudna; Vila-Sanjurjo, Antón

2008-01-01

279

Inhibition of palmito polyphenoloxidase by halide salts.  

PubMed

The inhibitory properties of halide salts on palmito polyphenoloxidase (PPO) are described. Halide salts have the same inhibitory effect on the two forms of palmito PPO separated by hydrophobic chromatography. Fluoride and chloride ions showed a non-competitive, mixed type inhibition while bromide and iodide ions were found to be non-competitive inhibitors. A study of the Ki for the different halide salts showed that the smaller F- ion is a stronger inhibitor than I- and Br- and that Cl- has the highest Ki value. This suggests that the active site of the palmito PPO is not easily accessible. The inhibition by chloride and fluoride ion was found to be pH-dependent. The inhibitory effects of these ions increased with a decrease in pH. It is suggested that halide ions (X) could bind to either the protonated enzyme (EH) or the protonated substrate-enzyme complex (EHS) to yield inactive forms EHX and EHSX, respectively. PMID:9795866

Robert, C; Rouch, C; Cadet, F

1998-07-01

280

Allosteric inhibition of the neuropeptidase neurolysin.  

PubMed

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

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

281

Hyaluronan inhibits BMP-induced osteoblast differentiation.  

PubMed

Hyaluronan (HA), one of the major structural extracellular components in cartilage, regulates cellular responses via receptors such as CD44. However, the direct effects of HA on osteoblastic differentiation has not been studied in detail. Here, we investigated the effects of HA (molecular weight: 900-1200kDa) on osteoblastic differentiation that was induced by bone morphogenetic protein (BMP) in C2C12 cells (mouse myoblastic cells) and ST2 cells (mouse bone marrow cells). BMP-induced osteoblastic differentiation and Smad1/Smad5/Smad8 phosphorylation were downregulated by HA. Use of the CD44-blocking antibody restored HA-induced inhibition of osteoblastic differentiation and Smad1/Smad5/Smad8 phosphorylation. Our results indicate that HA inhibits BMP-induced osteoblastic differentiation through the CD44 receptor. PMID:25592835

Kaneko, Keiko; Higuchi, Chikahisa; Kunugiza, Yasuo; Yoshida, Kiyoshi; Sakai, Takashi; Yoshikawa, Hideki; Nakata, Ken

2015-02-13

282

Preventing MIC through microbial adhesion inhibition  

SciTech Connect

The key to the alteration of conditions at a metal surface before the initiation of microbially induced corrosion (MIC) is the formation of a biofilm. Thus, prevention of bacterial adhesion processes on metal surfaces would be one of the potential weapons to avoid MIC. Serum globulin and by-products were used to prevent bacterial adhesion on different corrosion resistant metal surfaces generally used as implantable biomaterials. In this paper an immunoglobulin combination (IgA, IgG and IgM) has been used to prevent the formation of Pseudomonas fluorescens (P.fluorescens) biofilms on carbon steel and two different types of stainless steel (SS). A marked inhibition of bacterial adhesion was found under different experimental conditions. Several microscopic techniques were used for assessing adhesion inhibition while the electrochemical behavior of the steels was evaluated by means of different electrochemical techniques applied in the presence and in the absence of the immunoglobulins.

Videla, H.A. [Univ. of La Plata (Argentina). Dept. of Chemistry; Guiamet, P.S.; Gomez de Saravia, S.G. [INIFTA, La Plata (Argentina). Bioelectrochemistry Section

1998-12-31

283

Breaking of seed dormancy by catalase inhibition.  

PubMed Central

Germination of some dormant seeds is promoted by solutions of thiourea, sodium nitrite, and hydroxylamine salts. The promotions are accompanied by irreversible inhibition of catalase (EC 1.11.1.6) in extracts from the seeds. The seeds are also promoted in germination by catechol and pyrogallol solutions. These effects are recorded for lettuce (Lactuca sativa L. cv. Grand Rapids) and pigweed (Amaranthus albus L.) seeds. The results indicae that metabolically derived hydrogen peroxide, spared from decomposition by catalase inhibition, oxidizes reduced NADPH required as the oxidant in the pentose pathway of glucose use. The metabolic system for such use of H2O2 involves the enzymes, peroxidase (EC 1.11.1.7) and pyridine nucleotide quinone oxidoreductase (EC 1.6.99.2), which are present in the dormant seed prior to imbibition of water. PMID:235126

Hendricks, S B; Taylorson, R B

1975-01-01

284

Emotional inhibition: a discourse analysis of disclosure.  

PubMed

Evidence generated within the emotional disclosure paradigm (EDP) suggests that talking or writing about emotional experiences produces health benefits, but recent meta-analyses have questioned its efficacy. Studies within the EDP typically rely upon a unidimensional and relatively unsophisticated notion of emotional inhibition, and tend to use quantitative forms of content analysis to identify associations between percentages of word types and positive or negative health outcomes. In this article, we use a case study to show how a qualitative discourse analysis has the potential to identify more of the complexity linking the disclosure practices and styles that may be associated with emotional inhibition. This may illuminate the apparent lack of evidence for efficacy of the EDP by enabling more comprehensive theorisations of the variations within it. PMID:21678182

Ellis, Darren; Cromby, John

2012-01-01

285

GROWTH INHIBITION BY SUBSTANCES IN LIVER  

PubMed Central

Certain tissue constituents inhibitory to cell growth, extracted from liver, are described. The findings indicate that inhibitory material is adsorbed to colloids in the native state and is freed from them by alcohol extraction. One inhibitor, ethanolamine, has been isolated. This substance differs in its biological properties from the bulk of the inhibitory material present in liver. Progress in purification of other inhibitors is described, and it is shown that inhibition by these extracts is not correlated with surface activity or with the presence of pigmented constituents. The inhibitors have common properties which suggest that they are of physiological significance in the regulation of growth: action over a wide range of concentrations at which other cell functions are undamaged; reversibility of action; presence in adult liver in concentrations near those which inhibit growth in vitro, while in embryo liver they are found only in much lower concentrations. PMID:19870972

Brues, Austin M.; Subbarow, Y.; Jackson, Elizabeth B.; Aub, Joseph C.

1940-01-01

286

Glucosamine Inhibits Inducible Nitric Oxide Synthesis  

Microsoft Academic Search

Glucosamine is widely used in Europe for treatment of arthritis in humans. Based on recent findings that excess production of nitric oxide (NO) by inducible NO synthase (iNOS) mediates the pathogenesis of arthritis, we hypothesized that glucosamine may inhibit NO synthesis. To test this hypothesis, we used an in vivo rat model of lipopolysaccharide (LPS)-induced inflammation. Intravenous administration of d-glucosamine

Cynthia J. Meininger; Katherine A. Kelly; Hui Li; Tony E. Haynes; Guoyao Wu

2000-01-01

287

Tetracyclines Inhibit Protein Glycation in Experimental Diabetes  

Microsoft Academic Search

Glycation of proteins, which is accelerated in the diabetic state, has been implicated in many of the long-term complications of diabetes. This process can be inhibited by members of the tetracycline family of compounds. This novel finding is supported by studies conducted on drug (streptozotocin)induced Type I and genetic (ZDF\\/Gmi-fa\\/fa) Type II diabetic rats. These animals were orally gavaged daily

M. E. Ryan; N. S. Ramamurthy; L. M. Golub

1998-01-01

288

Evidence of Dopaminergic Processing of Executive Inhibition  

PubMed Central

Inhibition of unwanted response is an important function of the executive system. Since the inhibitory system is impaired in patients with dysregulated dopamine system, we examined dopamine neurotransmission in the human brain during processing of a task of executive inhibition. The experiment used a recently developed dynamic molecular imaging technique to detect and map dopamine released during performance of a modified Eriksen's flanker task. In this study, young healthy volunteers received an intravenous injection of a dopamine receptor ligand (11C-raclopride) after they were positioned in the PET camera. After the injection, volunteers performed the flanker task under Congruent and Incongruent conditions in a single scan session. They were required to inhibit competing options to select an appropriate response in the Incongruent but not in the Congruent condition. The PET data were dynamically acquired during the experiment and analyzed using two variants of the simplified reference region model. The analysis included estimation of a number of receptor kinetic parameters before and after initiation of the Incongruent condition. We found increase in the rate of ligand displacement (from receptor sites) and decrease in the ligand binding potential in the Incongruent condition, suggesting dopamine release during task performance. These changes were observed in small areas of the putamen and caudate bilaterally but were most significant on the dorsal aspect of the body of left caudate. The results provide evidence of dopaminergic processing of executive inhibition and demonstrate that neurochemical changes associated with cognitive processing can be detected and mapped in a single scan session using dynamic molecular imaging. PMID:22162756

Badgaiyan, Rajendra D.; Wack, David

2011-01-01

289

Henri Laborit and the inhibition of action  

PubMed Central

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

Kunz, Edward

2014-01-01

290

Factors that inhibit snowball Earth simulation  

Microsoft Academic Search

A coupled ocean-atmosphere general circulation model with a thermodynamic sea-ice model, the Fast Ocean Atmosphere Model version 1.5, is used to investigate the factors that inhibit the simulation of global sea ice. In the control experiment with reduced solar luminosity (93% of modern), low atmospheric pCO2 (140 ppm), and an idealized tropical continent, the sea-ice margin equilibrates at ?27° latitude.

C. J. Poulsen; R. L. Jacob

2004-01-01

291

Structural Basis for Sirtuin Activity and Inhibition*  

PubMed Central

Sir2 proteins, or sirtuins, are a family of enzymes that catalyze NAD+-dependent deacetylation reactions and can also process ribosyltransferase, demalonylase, and desuccinylase activities. More than 40 crystal structures of sirtuins have been determined, alone or in various liganded forms. These high-resolution architectural details lay the foundation for understanding the molecular mechanisms of catalysis, regulation, substrate specificity, and inhibition of sirtuins. In this minireview, we summarize these structural features and discuss their implications for understanding sirtuin function. PMID:23086949

Yuan, Hua; Marmorstein, Ronen

2012-01-01

292

When inhibition not excitation synchronizes neural firing  

Microsoft Academic Search

Excitatory and inhibitory synaptic coupling can have counter-intuitive effects on the synchronization of neuronal firing. While it might appear that excitatory coupling would lead to synchronization, we show that frequently inhibition rather than excitation synchronizes firing. We study two identical neurons described by integrate-and-fire models, general phase-coupled models or the Hodgkin-Huxley model with mutual, non-instantaneous excitatory or inhibitory synapses between

CARL VAN VREESWIJK; L. F. Abbott; G. Bard Ermentrout

1994-01-01

293

Cortisol inhibits apoptosis in carp neutrophilic granulocytes  

Microsoft Academic Search

The direct effect of cortisol treatment on carp neutrophil viability was examined in vitro. Cortisol treatment caused an inhibition of neutrophil apoptosis. The effect was blocked by glucocorticoid receptor blocker RU486, showing that rescue from apoptosis was receptor mediated. Using binding studies with radioactive cortisol, a single class of glucocorticoid receptors was detected with high affinity (Kd=2.6 nM) and low

F. A. A. Weyts; G. Flik; B. M. L. Verburg-van Kemenade

1998-01-01

294

Azithromycin Inhibits Quorum Sensing in Pseudomonas aeruginosa  

Microsoft Academic Search

We report that 2 mg of azithromycin\\/ml inhibits the quorum-sensing circuitry of Pseudomonas aeruginosa strain PAO1. Addition of synthetic autoinducers partially restored the expression of the trancriptional acti- vator-encoding genes lasR and rhlR but not that of the autoinducer synthase-encoding gene lasI. We propose that azithromycin interferes with the synthesis of autoinducers, by an unknown mechanism, leading to a reduction

KAZUHIRO TATEDA; RACHEL COMTE; JEAN-CLAUDE PECHERE; THILO KOHLER; KEIZO YAMAGUCHI; CHRISTIAN VAN DELDEN

2001-01-01

295

Inhibition of glomerular cell apoptosis by heparin  

Microsoft Academic Search

Inhibition of glomerular cell apoptosis by heparin.BackgroundHeparin, the multifunctional glycosaminoglycan, has been considered a therapeutic agent for glomerular diseases. Although a number of biological properties are postulated to explain its therapeutic utility, it is unknown whether heparin affects cell survival in the glomerulus. In this report, we investigated the effect of heparin on apoptosis of glomerular cells.MethodsCultured rat mesangial cells

Yoshihisa Ishikawa; Masanori Kitamura

1999-01-01

296

Inhibition of Light Tunneling in Waveguide Arrays  

NASA Astrophysics Data System (ADS)

We report the observation of almost perfect light tunneling inhibition at the edge and inside laser-written waveguide arrays due to band collapse. When the refractive index of the guiding channels is harmonically modulated along the propagation direction and out-of-phase in adjacent guides, light is trapped in the excited waveguide over a long distance due to resonances. The phenomenon can be used for tuning the localization threshold power.

Szameit, A.; Kartashov, Y. V.; Dreisow, F.; Heinrich, M.; Pertsch, T.; Nolte, S.; Tünnermann, A.; Vysloukh, V. A.; Lederer, F.; Torner, L.

2009-04-01

297

Caffeine Inhibits Acetylcholinesterase, But Not Butyrylcholinesterase  

PubMed Central

Caffeine is an alkaloid with a stimulant effect in the body. It can interfere in transmissions based on acetylcholine, epinephrine, norepinephrine, serotonin, dopamine and glutamate. Clinical studies indicate that it can be involved in the slowing of Alzheimer disease pathology and some other effects. The effects are not well understood. In the present work, we focused on the question whether caffeine can inhibit acetylcholinesterase (AChE) and/or, butyrylcholinesterase (BChE), the two enzymes participating in cholinergic neurotransmission. A standard Ellman test with human AChE and BChE was done for altering concentrations of caffeine. The test was supported by an in silico examination as well. Donepezil and tacrine were used as standards. In compliance with Dixon’s plot, caffeine was proved to be a non-competitive inhibitor of AChE and BChE. However, inhibition of BChE was quite weak, as the inhibition constant, Ki, was 13.9 ± 7.4 mol/L. Inhibition of AChE was more relevant, as Ki was found to be 175 ± 9 ?mol/L. The predicted free energy of binding was ?6.7 kcal/mol. The proposed binding orientation of caffeine can interact with Trp86, and it can be stabilize by Tyr337 in comparison to the smaller Ala328 in the case of human BChE; thus, it can explain the lower binding affinity of caffeine for BChE with reference to AChE. The biological relevance of the findings is discussed. PMID:23698772

Pohanka, Miroslav; Dobes, Petr

2013-01-01

298

Inhibition of thymocyte apoptosis by berberine  

Microsoft Academic Search

To find anti-apoptotic substances in plant resources, a microassay method for estimating DNA fragmentation was established using fluorochrome 3,5-diaminobenzoic acid dihydrochloride. Examination was made of various herbal medicines for inhibitory effects on glucocorticoid-induced apoptosis in thymocytes. Several Kampo medicines, e.g. Oren-gedoku-to and San'o-shashin-to, were found to inhibit dexamethasone-induced apoptosis in murine thymocytes. Some of these medicines contain Coptidis rhizoma (CR)

Naoko Miura; Masahiro Yamamoto; Toshiyuki Ueki; Toshiyuki Kitani; Kazunori Fukcuda; Yasuhiro Komatsu

1997-01-01

299

Heme oxygenase metabolites inhibit tubuloglomerular feedback (TGF).  

PubMed

Tubuloglomerular feedback (TGF) is the mechanism by which the macula densa (MD) senses increases in luminal NaCl concentration and sends a signal to constrict the afferent arteriole (Af-Art). The kidney expresses constitutively heme oxygenase-2 (HO-2) and low levels of HO-1. HOs release carbon monoxide (CO), biliverdin, and free iron. We hypothesized that renal HOs inhibit TGF via release of CO and biliverdin. Rabbit Af-Arts and attached MD were simultaneously microperfused in vitro. The TGF response was determined by measuring Af-Art diameter before and after increasing NaCl in the MD perfusate. When HO activity was inhibited by adding stannous mesoporphyrin (SnMP) to the MD perfusate, the TGF response increased from 2.1+/-0.2 to 4.1+/-0.4 microm (P=0.003, control vs. SnMP, n=7). When a CO-releasing molecule, (CORM-3; 50 microM), was added to the MD perfusate, the TGF response decreased by 41%, from 3.6+/-0.3 to 2.1+/-0.2 microm (P<0.001, control vs. CORM-3, n=12). When CORM-3 at 100 microM was added to the perfusate, it completely blocked the TGF response, from 4.2+/-0.4 to -0.2+/-0.3 microm (P<0.001, control vs. CORM-3, n=6). When biliverdin was added to the perfusate, the TGF response decreased by 79%, from 3.4+/-0.3 to 0.7+/-0.4 microm (P=0.001, control vs. biliverdin, n=6). The effects of SnMP and CORM-3 were not blocked by inhibition of nitric oxide synthase. We concluded that renal HO inhibits TGF probably via release of CO and biliverdin. HO regulation of TGF is a novel mechanism that could lead to a better understanding of the control of renal microcirculation and function. PMID:18715939

Ren, YiLin; D'Ambrosio, Martin A; Wang, Hong; Liu, Ruisheng; Garvin, Jeffrey L; Carretero, Oscar A

2008-10-01

300

Phytic Acid Inhibits Lipid Peroxidation In Vitro  

PubMed Central

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??M and 500??M 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??M and 500??M significantly suppressed decomposition of linoleic acid hydroperoxides. Moreover, PA at the tested nontoxic concentrations (100??M and 500??M) 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

W?glarz, Ludmi?a; Dzier?ewicz, Zofia

2013-01-01

301

Trace element inhibition of phytase activity.  

PubMed

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?inhibit exogenous phytase activity. PMID:25416530

Santos, T; Connolly, C; Murphy, R

2015-02-01

302

Wnt signaling inhibits CTL memory programming.  

PubMed

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. PMID:23911398

Xiao, Zhengguo; Sun, Zhifeng; Smyth, Kendra; Li, Lei

2013-12-01

303

Method for inhibiting corrosion in particulate zinc  

SciTech Connect

A method is described for the inhibition of corrosion in particulate zinc, which comprises the step of subjecting said zinc in the form of an alkaline slurry to treatment by a corrosion inhibiting effective amount of a corrosion inhibitor which is at least one oxide selected from the group consisting of oxides of antimony, bismuth, cadmium, gallium, indium, lead, mercury, thallium and tin, wherein zinc has been obtained by an electrolytic process for regeneration of zinc in an at least partially spent slurry for use in metal-air batteries which slurry comprises an admixture of at least components (a) and (b), of the following components (a), (b), (c), (d), (e), (f) and (g): (a) zinc which has been at least partly oxidized to an oxidation product selected from zinc oxide and zincates; (b) an aqueous solution of at least one Group 1a metal comprising anions selected from the group consisting of hydroxide and zincate; (c) an inorganic inhibitor ingredient effective to inhibit an interaction of zinc and at least one Group 1a metal hydroxide in the aqueous solution, which would otherwise result in an evolution of hydrogen gas; (d) a gelling agent; (e) a filler selected from the group consisting of particulate and fibrous fillers; (f) a labelling agent; (g) a dissolved electrolyte extender.

Goldstein, J.; Meitav, A,; Lezion, R.; Kravitz, M.

1993-08-03

304

Myostatin inhibition: a potential performance enhancement strategy?  

PubMed

A decade has passed since myostatin was first identified as a negative regulator of muscle growth. Since then, studies in both humans and animals have demonstrated that decreasing the levels of this growth factor or inhibiting its function can dramatically increase muscle size, and a number of therapeutic applications of myostatin inhibition to the treatment of myopathies and muscle atrophy have been proposed. As such treatments would be likely to also stimulate muscle growth in healthy individuals, there is a growing concern among anti-doping authorities that myostatin inhibitors may be among the next generation of ergogenic pharmaceuticals or even in the vanguard of "gene doping" technology. While the ability to stimulate muscle growth through myostatin inhibition is well documented, a growing body of evidence suggests such increases may not translate into an improvement in athletic performance. This article briefly reviews the function of this potent regulator of muscle development and explores the potential therapeutic uses, and potential ergogenic abuses, of myostatin manipulation. PMID:18248537

Fedoruk, M N; Rupert, J L

2008-04-01

305

Menaquinone Analogs Inhibit Growth of Bacterial Pathogens  

PubMed Central

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 ?g/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

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

306

Pharmacological Inhibition of Feline Immunodeficiency Virus (FIV)  

PubMed Central

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

Mohammadi, Hakimeh; Bienzle, Dorothee

2012-01-01

307

Ormeloxifene efficiently inhibits ovarian cancer growth.  

PubMed

Ovarian cancer continues to be a leading cause of cancer related deaths for women. Anticancer agents effective against chemo-resistant cells are greatly needed for ovarian cancer treatment. Repurposing drugs currently in human use is an attractive strategy for developing novel cancer treatments with expedited translation into clinical trials. Therefore, we examined whether ormeloxifene (ORM), a non-steroidal Selective Estrogen Receptor Modulator (SERM) currently used for contraception, is therapeutically effective at inhibiting ovarian cancer growth. We report that ORM treatment inhibits cell growth and induces apoptosis in ovarian cancer cell lines, including cell lines resistant to cisplatin. Furthermore, ORM treatment decreases Akt phosphorylation, increases p53 phosphorylation, and modulates the expression and localization patterns of p27, cyclin E, cyclin D1, and CDK2. In a pre-clinical xenograft mouse ORM treatment significantly reduces tumorigenesis and metastasis. These results indicate that ORM effectively inhibits the growth of cisplatin resistant ovarian cancer cells. ORM is currently in human use and has an established record of patient safety. Our encouraging in vitro and pre-clinical in vivo findings indicate that ORM is a promising candidate for the treatment of ovarian cancer. PMID:25306892

Maher, Diane M; Khan, Sheema; Nordquist, Jordan L; Ebeling, Mara C; Bauer, Nichole A; Kopel, Lucas; Singh, Man Mohan; Halaweish, Fathi; Bell, Maria C; Jaggi, Meena; Chauhan, Subhash C

2015-01-28

308

Stress-induced plasticity of GABAergic inhibition  

PubMed Central

GABAergic neurotransmission is highly plastic, undergoing dynamic alterations in response to changes in the environment, such as following both acute and chronic stress. Stress-induced plasticity of GABAergic inhibition is thought to contribute to changes in neuronal excitability associated with stress, which is particularly relevant for stress-related disorders and seizure susceptibility. Here we review the literature demonstrating several mechanisms altering GABAergic inhibition associated with stress, including brain region-specific alterations in GABAA receptor (GABAAR) subunit expression, changes in chloride homeostasis, and plasticity at GABAergic synapses. Alterations in the expression of specific GABAAR subunits have been documented in multiple brain regions associated with acute or chronic stress. In addition, recent work demonstrates stress-induced alterations in GABAergic inhibition resulting from plasticity in intracellular chloride levels. Acute and chronic stress-induced dephosphorylation and downregulation of the K+/Cl? co-transporter, KCC2, has been implicated in compromising GABAergic control of corticotropin-releasing hormone (CRH) neurons necessary for mounting the physiological response to stress. Acute stress also unmasks the capacity for both long-term potentiation and long-term depression, in distinct temporal windows, at GABAergic synapses on parvocellular neuroendocrine cells (PNCs) in the paraventricular nucleus (PVN) of the hypothalamus. This review highlights the complexity in the plasticity of GABAergic neurotransmission associated with stress and the relationship to neuronal excitability, including alterations in GABAAR expression, synaptic plasticity at GABAergic synapses, and changes in chloride homeostasis. PMID:24936173

Maguire, Jamie

2014-01-01

309

Mechanism of nitrite inhibition of cellular respiration in Pseudomonas aeruginosa  

Microsoft Academic Search

One of the principal mechanisms of nitrite inhibition of cellular respiration has been considered to be the interference with the action of iron-containing enzymes. In procaryotic systems, the effect of nitrite on cellular metabolism remains unclear. This study provides evidence which shows a direct inhibition by a low concentration of nitrite on a highly purified oxidase inPseudomonas aeruginosa. The inhibition

Tsanyen Yang

1985-01-01

310

Carboxypeptidase A: mechanism of zinc inhibition.  

PubMed

Zinc ions competitively inhibit carboxypeptidase A from bovine pancreas. The state(s) of hydroxylation of zinc and their possible site(s) of interaction with the enzyme have been investigated by determining the strength of zinc inhibition over pH range 4.6-10.5. The inhibition kinetics were recorded under stopped-flow conditions using the alpha-Val isozyme and the peptide substrate Dns-Gly-Ala-Phe in 0.5 M NaCl at 25 degrees C. The pH dependence of pKI follows a pattern which indicates that the enzyme is selectively inhibited by zinc monohydroxide, ZnOH+ (KI = 7.1 X 10(-7) M). The formation of the inhibitory ZnOH+ complex from fully hydrated Zn2+ is characterized by an ionization constant of 9.05, and the consecutive conversion of ZnOH+ to Zn(OH)2, Zn(OH)3-, and Zn(OH)4(2-) complexes takes place with ionization constants of 9.75, 10.1, and 10.5, respectively. Ionization of a ligand, LH, in the enzyme's inhibitory site (pKLH 5.8) is obligatory for binding of the ZnOH+ complex. The enzymatic activity (kcat/Km) is influenced by three ionizable groups: pKEH2 5.78, pKEH 8.60, and pKE 10.2. Since the values of pKLH and pKEH2 are virtually identical, it is possible that the inhibitory ZnOH+ complex interacts with the group responsible for pKEH2. Previous studies have suggested that pKEH2 reflects the ionization of Glu-270 and its interaction with a water molecule coordinated to the catalytic zinc ion. It is proposed that the inhibitory zinc ion binds to the carboxylate of Glu-270 and that the inhibition process is specific for zinc monohydroxide because it allows the formation of a stabilizing hydroxide bridge between the inhibitory and catalytic zinc ions. PMID:2611251

Larsen, K S; Auld, D S

1989-12-12

311

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

PubMed

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. PMID:24551203

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

312

Photo-Activated Psoralen Binds the ErbB2 Catalytic Kinase Domain, Blocking ErbB2 Signaling and Triggering Tumor Cell Apoptosis  

PubMed Central

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 (p85ErbB2) 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 p85ErbB2. Here we show that PUVA reduced p85ErbB2 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. PMID:24551203

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

313

Inhibition of prostaglandin E2 synthesis by SC-560 is independent of cyclooxygenase 1 inhibition.  

PubMed

Prostaglandin E2 (PGE2) produced by cyclooxygenase-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) plays an important role in the pathophysiology of inflammation, pain, and fever. We investigated the actions of TNFalpha toward stimulation of PGE2 synthesis in primary spinal cord neurons. TNFalpha induced COX-2 and mPGES-1 expression in neurons, followed by formation of PGE2, which was blocked by a selective COX-2 inhibitor. Surprisingly, the "selective COX-1" inhibitor SC-560 completely inhibited TNFalpha-induced PGE2 synthesis in neurons at nanomolar concentrations. Moreover, SC-560 inhibited PGE2 and thromboxane A2 synthesis in human monocytes and platelets with IC50 of 1.8 nM and 2.5 nM, respectively. SC-560 treatment neither altered TNFalpha-induced COX-2 or mPGES-1 expression nor did the addition of the calcium ionophore A23187 or arachidonic acid reverse the inhibition by SC-560. Moreover, no influence of SC-560 on PGE2 synthase activities or PGE2 transport was seen. Most importantly, SC-560 blocked TNFalpha-induced PGE2 synthesis in COX-1-deficient spinal cord neurons, demonstrating a COX-1-independent inhibition of PGE2 synthesis. Although SC-560 inhibited LPS-induced PGE2 synthesis in neurons and RAW264.7 macrophages in whole cell assays, no inhibition was observed in lysates of the same cells. Taken together our data demonstrate that SC-560 acts at least in some cell types as an unselective COX inhibitor despite its selectivity toward COX-1 under cell-free conditions. PMID:16816110

Brenneis, Christian; Maier, Thorsten J; Schmidt, Ronald; Hofacker, Annette; Zulauf, Lars; Jakobsson, Per-Johan; Scholich, Klaus; Geisslinger, Gerd

2006-07-01

314

Quassinoid Inhibition of AP-1 Function Does Not Correlate with Cytotoxicity or Protein Synthesis Inhibition†  

PubMed Central

Several quassinoids were identified in a high-throughput screening assay as inhibitors of the transcription factor AP-1. Further biological characterization revealed that while their effect was not specific to AP-1, protein synthesis inhibition and cell growth assays were inconsistent with a mechanism of simple protein synthesis inhibition. Numerous plant extracts from the plant family Simaroubaceae were also identified in the same screen; bioassay-guided fractionation of one extract (Ailanthus triphylla) yielded two known quassinoids, ailanthinone (3) and glaucarubinone (4), which were also identified in the pure compound screening procedure. PMID:19199792

Beutler, John A.; Kang, Moon-Il; Robert, Francis; Clement, Jason A.; Pelletier, Jerry; Colburn, Nancy H.; McKee, Tawnya C.; Goncharova, Ekaterina; McMahon, James B.; Henrich, Curtis J.

2010-01-01

315

Inhibition, Executive Function, and Freezing of Gait  

PubMed Central

Background Studies suggest that freezing of gait (FoG) in people with Parkinson’s disease (PD) is associated with declines in executive function (EF). However, EF is multi-faceted, including three dissociable components: inhibiting prepotent responses, switching between task sets, and updating working memory. Objective This study investigated which aspect of EF is most strongly associated with FoG in PD. Method Three groups were studied: adults with PD (with and without FoG) and age-matched, healthy adults. All participants completed a battery of cognitive tasks previously shown to discriminate among the three EF components. Participants also completed a turning-in-place task that was scored for FoG by neurologists blind to subjects’ self-reported FoG. Results Compared to both other groups, participants with FoG showed significant performance deficits in tasks associated with inhibitory control, even after accounting for differences in disease severity, but no significant deficits in task-switching or updating working memory. Surprisingly, the strongest effect was an intermittent tendency of participants with FoG to hesitate, and thus miss the response window, on go trials in the Go-Nogo task. The FoG group also made slower responses in the conflict condition of the Stroop task. Physician-rated FoG scores were correlated both with failures to respond on go trials and with failures to inhibit responses on nogo trials in the Go-Nogo task. Conclusion These results suggest that FoG is associated with a specific inability to appropriately engage and release inhibition, rather than with a general executive deficit. PMID:24496099

Cohen, Rajal G.; Klein, Krystal A.; Nomura, Mariko; Fleming, Michael; Mancini, Martina; Giladi, Nir; Nutt, John G.; Horak, Fay B.

2014-01-01

316

c-Myb inhibits myoblast fusion.  

PubMed

Satellite cells represent a heterogeneous population of stem and progenitor cells responsible for muscle growth, repair and regeneration. We investigated whether c-Myb could play a role in satellite cell biology because our previous results using satellite cell-derived mouse myoblast cell line C2C12 showed that c-Myb was expressed in growing cells and downregulated during differentiation. We detected c-Myb expression in activated satellite cells of regenerating muscle. c-Myb was also discovered in activated satellite cells associated with isolated viable myofiber and in descendants of activated satellite cells, proliferating myoblasts. However, no c-Myb expression was detected in multinucleated myotubes originated from fusing myoblasts. The constitutive expression of c-Myb lacking the 3' untranslated region (3' UTR) strongly inhibited the ability of myoblasts to fuse. The inhibition was dependent on intact c-Myb transactivation domain as myoblasts expressing mutated c-Myb in transactivation domain were able to fuse. The absence of 3' UTR of c-Myb was also important because the expression of c-Myb coding region with its 3' UTR did not inhibit myoblast fusion. The same results were repeated in C2C12 cells as well. Moreover, it was documented that 3' UTR of c-Myb was responsible for downregulation of c-Myb protein levels in differentiating C2C12 cells. DNA microarray analysis of C2C12 cells revealed that the expression of several muscle-specific genes was downregulated during differentiation of c-Myb-expressing cells, namely: ACTN2, MYH8, TNNC2, MYOG, CKM and LRRN1. A detailed qRT-PCR analysis of MYOG, TNNC2 and LRRN1 is presented. Our findings thus indicate that c-Myb is involved in regulating the differentiation program of myogenic progenitor cells as its expression blocks myoblast fusion. PMID:24204667

Kaspar, Petr; Ilencikova, Kristina; Zikova, Martina; Horvath, Ondrej; Cermak, Vladimir; Bartunek, Petr; Strnad, Hynek

2013-01-01

317

Enkephalins inhibit intestinal motility: mode of action.  

PubMed

In the guinea pig isolated terminal ileum the opioid pentapeptides, methionine-enkephalin and leucine-enkephalin, dose-dependently inhibit contractile responses induced by electrical field stimulation releasing endogenous acetylcholine, and by specific noncholinergic compounds including histamine, barium chloride, and beta-acetyl-digoxin. Tissue levels of cAMP and cGMP remain unchanged. We conclude that enkephalins exert their effects by a direct action at or within the muscle cell and may play a physiological role in the local control of the gut smooth muscle motility. PMID:857559

Mitznegg, P; Domschke, W; Sprügel, W; Domschke, S; Subramanian, N; Wünsch, E; Moroder, L; Demling, L

1977-04-01

318

Saw palmetto ethanol extract inhibits adipocyte differentiation.  

PubMed

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-EBP? and PPAR?. 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. PMID:23179316

Villaverde, Nicole; Galvis, Adriana; Marcano, Adriana; Priestap, Horacio A; Bennett, Bradley C; Barbieri, M Alejandro

2013-07-01

319

GALVANOTROPISM AND "REVERSAL OF INHIBITION" BY STRYCHNINE  

PubMed Central

The cathodically galvanotropic orientation of nemerteans, Lineus, and the anodic orientation of the gephyrean Echiurus, are reversed by the action of strychnine under conditions such that the typical "reversal of inhibition" induced by this substance is apparent. Nicotine does not give this result. Since it is necessary to assume that the strychnine effect is due to action upon the central ganglia, and since the galvanotropic effect depends upon action of the current on nerve cell bodies of the central ganglia, it must be assumed that the locus of reversal by strychnine is not perikaryal, but presumably synaptic. PMID:19872331

Crozier, W. J.

1927-01-01

320

Formation and inhibition of photochemical smog  

SciTech Connect

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.

Heicklen, J.

1987-01-01

321

ACE-INHIBITION AND PHYSICAL FUNCTION  

PubMed Central

Objectives Aim of the present study is to evaluate whether an ACE inhibitor intervention is able to significantly improve physical performance and muscle strength in a sample of older persons. Design Double-blind, cross-over, randomized, placebo-controlled trial. Setting The Trail of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study. Participants Two hundred fiftyseven subjects aged 55 years and older with high cardiovascular risk profile. Intervention Six month of fosinopril use versus placebo. Measurements The Short Physical Performance Battery score (rescaled to obtain a continuous variable ranging from 0 to 3 points), and the hand grip strength were measured at the baseline visit, and after 6 and 12 months of follow-up. Paired t-test analyses were performed to compare results of physical function measures after ACE inhibition and placebo interventions. Results Mean age of the sample population was 65.97 (standard deviation 7.41) years old. No statistically significant difference was found at the Short Physical Performance Battery (p=0.23) and hand grip strength (p=0.57) results after ACE inhibition (2.113, standard deviation [SD] 0.284; and 37.044 kg, SD 12.993 kg, respectively) compared to placebo (2.096, SD 0.298; and 36.898 kg, SD 13.178 kg, respectively). No significant effects from ACE inhibition were also found when the three subtests composing the Short Physical Performance Battery (i.e., 4-meter walking speed, balance, and chair stand tests) were separately analyzed. Consistent negative results were obtained after analyses were restricted to participants showing the highest compliance to treatment and/or receiving the maximum fosinopril dosage. Conclusion No significant modifications in physical performance and muscle strength were reported after 6 months of fosinopril use in older persons with high cardiovascular risk profile. Given these negative findings, it is possible that the beneficial effects of ACE inhibitors on physical function might be due to the activation of a virtuous cycle determined by an improved cardiovascular system. Further specifically designed studies are needed to confirm our findings, and expand them to different populations and ACE inhibitors. If our findings will be confirmed, the extra-cardiovascular properties of ACE inhibitors in older persons might be substantially resized. PMID:20129212

Cesari, Matteo; Pedone, Claudio; Incalzi, Raffaele Antonelli; Pahor, Marco

2009-01-01

322

Inhibition of saccades elicits attentional suppression.  

PubMed

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. PMID:23685392

Dhawan, Saurabh; Deubel, Heiner; Jonikaitis, Donatas

2013-01-01

323

Controlling apoptosis by inhibition of caspases.  

PubMed

The intracellular cysteine proteinases grouped under the common name of caspases are important participants in the process of programmed cell death called apoptosis. Of the nearly fourteen mammalian members discovered thus far caspase 1 or (interleukin 1beta converting enzyme; ICE), and possibly other related family members also serve as activator of cytokines. In general, caspases act on a number of cellular targets including other caspase family members leading ultimately to apopto4 4is through a highly integrated and regulated biological, biochemical and genetic mechanism. The proper execution of apoptosis is crucial during developmental stages and continues to be of critical importance for the well being of the mature organism. However, in a number of degenerative diseases the pathological states are characterized by an exacerbated loss of certain types of cells, cellular death that has morphological characteristics of apoptosis. Fortunately, it has been known for sometime that induced apoptosis that proceeds through the activation of caspases can be inhibited to rescue these cells and allow them to remain viable. This realization has attracted attention towards caspases as likely targets for pharmacological intervention, believing that inhibition of their enzymatic activity in the compromised cells will prevent the unwanted high rate of cellular death. Here we survey natural and synthetic inhibitors of caspases that have been reported to date, including some commonly used peptide inhibitors that serve as "tool reagents" in research and others that have been used to map inhibitor binding interaction in the active site. PMID:11945133

Concha, N O; Abdel-Meguid, S S

2002-03-01

324

Experimental muscle pain impairs descending inhibition  

PubMed Central

In chronic musculoskeletal pain conditions, the balance between supraspinal facilitation and inhibition of pain shifts towards an overall decrease in inhibition. Application of a tonic painful stimulus results in activation of diffuse noxious inhibitory controls (DNIC). The aims of the present experimental human study were (1) to compare DNIC, evoked separately, by hypertonic saline (6%)-induced muscle pain (tibialis anterior) or cold pressor pain; (2) to investigate DNIC evoked by concomitant experimental muscle pain and cold pressor pain, and (3) to analyze for gender differences. Ten males and 10 age matched females participated in two sessions. In the first session unilateral muscle pain or unilateral cold pressor pain were induced separately; in the second session unilateral muscle pain and unilateral cold pressor pain were induced concomitantly. Pressure pain thresholds (PPT) were measured around the knee joint before, during, and after DNIC induction. Cold pressor pain increased PPT in both males and females with greater increases in males. Hypertonic saline-evoked muscle pain significantly increased PPT in males but not in females. When cold pressor and muscle pain were applied concomitantly the PPT increases were smaller when compared to the individual sessions. This study showed for the first time that two concurrent conditioning tonic pain stimuli (muscle pain and cold pressor pain) cause less DNIC compared with either of the conditioning stimuli given alone; and males showed greater DNIC than females. This may explain why patients with chronic musculoskeletal pain have impaired DNIC. PMID:18977598

Arendt-Nielsen, Lars; Sluka, Kathleen A.; Nie, Hong Ling

2009-01-01

325

Inhibition Of Washed Sludge With Sodium Nitrite  

SciTech Connect

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.

Congdon, J. W.; Lozier, J. S.

2012-09-25

326

Targeting Sphingosine Kinase-1 To Inhibit Melanoma  

PubMed Central

SUMMARY Resistance to therapies develops rapidly for melanoma leading to more aggressive disease. Therefore, agents are needed that specifically inhibit proteins or pathways controlling the development of this disease, which can be combined, dependent on genes deregulated in a particular patient’s tumors. This study shows that elevated sphingosine-1-phosphate (S-1-P) levels resulting from increased activity of sphingosine kinase-1 (SPHK1) occur in advanced melanomas. Targeting SPHK1 using siRNA decreased anchorage dependent and independent growth as well as sensitized melanoma cells to apoptosis inducing agents. Pharmacological SPHK1 inhibitors SKI-I but not SKI-II decreased S-1-P content, elevated ceramide levels, caused a G2-M block and induced apoptotic cell death in melanomas. Targeting SPHK1 using siRNA or the pharmacological agent called SKI-I, decreased the levels of pAKT. Furthermore, SKI-I inhibited the expression of CYCLIN D1 protein and increased the activity of caspase-3/7, which in turn led to the degradation of PARP. In animals, SKI-I but not SKI-II retarded melanoma growth by 25-40%. Thus, targeting SPHK1 using siRNAs or SKI-I has therapeutic potential for melanoma treatment either alone or in combination with other targeted agents. PMID:22236408

Madhunapantula, SubbaRao V.; Hengst, Jeremy; Gowda, Raghavendra; Fox, Todd E.; Yun, Jong K; Robertson, Gavin P.

2012-01-01

327

Diacylglycerol Kinase Inhibition and Vascular Function  

PubMed Central

Diacylglycerol kinases (DGKs), a family of lipid kinases, convert diacylglycerol (DG) to phosphatidic acid (PA). Acting as a second messenger, DG activates protein kinase C (PKC). PA, a signaling lipid, regulates diverse functions involved in physiological responses. Since DGK modulates two lipid second messengers, DG and PA, regulation of DGK could induce related cellular responses. Currently, there are 10 mammalian isoforms of DGK that are categorized into five groups based on their structural features. These diverse isoforms of DGK are considered to activate distinct cellular functions according to extracellular stimuli. Each DGK isoform is thought to play various roles inside the cell, depending on its subcellular localization (nuclear, ER, Golgi complex or cytoplasm). In vascular smooth muscle, vasoconstrictors such as angiotensin II, endothelin-1 and norepinephrine stimulate contraction by increasing inositol trisphosphate (IP3), calcium, DG and PKC activity. Inhibition of DGK could increase DG availability and decrease PA levels, as well as alter intracellular responses, including calcium-mediated and PKC-mediated vascular contraction. The purpose of this review is to demonstrate a role of DGK in vascular function. Selective inhibition of DGK isoforms may represent a novel therapeutic approach in vascular dysfunction. PMID:21547002

Choi, Hyehun; Allahdadi, Kyan J.; Tostes, Rita C.A.; Webb, R. Clinton

2010-01-01

328

Perineural resiniferatoxin selectively inhibits inflammatory hyperalgesia.  

PubMed

Resiniferatoxin (RTX) is an ultrapotent capsaicin analog that binds to the transient receptor potential channel, vanilloid subfamily member 1 (TRPV1). There is a large body of evidence supporting a role for TRPV1 in noxious-mediated and inflammatory hyperalgesic responses. In this study, we evaluated low, graded, doses of perineural RTX as a method for regional pain control. We hypothesized that this approach can provide long-term, but reversible, blockade of a portion of nociceptive afferent fibers within peripheral nerves when given at a site remote from the neuronal perikarya in the dorsal root ganglia. Following perineural RTX application to the sciatic nerve, we demonstrated a significant inhibition of inflammatory nociception that was dose- and time-dependent. At the same time, treated animals maintained normal proprioceptive sensations and motor control, and other nociceptive responses were largely unaffected. Using a range of mechanical and thermal algesic tests, we found that the most sensitive measure following perineural RTX administration was inhibition of inflammatory hyperalgesia. Recovery studies showed that physiologic sensory function could return as early as two weeks post-RTX treatment, however, immunohistochemical examination of the DRG revealed a partial, but significant reduction in the number of the TRPV1-positive neurons. We propose that this method could represent a beneficial treatment for a range of chronic pain problems, including neuropathic and inflammatory pain not responding to other therapies. PMID:18199335

Neubert, John K; Mannes, Andrew J; Karai, Laszlo J; Jenkins, Alan C; Zawatski, Lanel; Abu-Asab, Mones; Iadarola, Michael J

2008-01-01

329

Inhibition of DNA replication by ultraviolet light.  

PubMed Central

DNA replication in ultraviolet-irradiated HeLa cells was studied by two different techniques: measurements of the kinetics of semiconservative DNA synthesis, and DNA fiber autoradiography. In examining the kinetics of semiconservative DNA synthesis, density label was used to avoid measuring the incorporation due to repair replication. The extent of inhibition varied with time. After doses of less than 10J/m2 the rate was initially depressed but later showed some recovery. After higher doses, a constant, low rate of synthesis was seen for at least the initial 6 h. An analysis of these data indicated that the inhibition of DNA synthesis could be explained by replication forks halting at pyrimidine dimers. DNA fiber autoradiography was used to further characterize replication after ultraviolet irradiation. The average length of labeled segments in irradiated cells increased in the time immediately after irradiation, and then leveled off. This is the predicted pattern if DNA synthesis in each replicon continued at its previous rate until a lesion is reached, and then halted. The frequency of lesions that block synthesis is approximately the same as the frequency of pyrimidine dimers. PMID:938725

Edenberg, H J

1976-01-01

330

IL-1? Inhibits Human Osteoblast Migration  

PubMed Central

Bone has a high capacity for self-renewal and repair. Prolonged local secretion of interleukin 1? (IL-1?), however, is known to be associated with severe bone loss and delayed fracture healing. Since induction of bone resorption by IL-1? may not sufficiently explain these pathologic processes, we investigated, in vitro, if and how IL-1? affects migration of multipotent mesenchymal stromal cells (MSC) or osteoblasts. We found that homogenous exposure to IL-1? significantly diminished both nondirectional migration and site-directed migration toward the chemotactic factors platelet-derived growth factor (PDGF)-BB and insulinlike growth factor 1 (IGF-1) in osteoblasts. Exposure to a concentration gradient of IL-1? induced an even stronger inhibition of migration and completely abolished the migratory response of osteoblasts toward PDGF-BB, IGF-1, vascular endothelial growth factor A (VEGF-A) and the complement factor C5a. IL-1? induced extracellular signal-regulated kinases 1 and 2 (ERK1/2) and c-Jun N-terminal kinases (JNK) activation and inhibition of these signaling pathways suggested an involvement in the IL-1? effects on osteoblast migration. In contrast, basal migration of MSC and their migratory activity toward PDGF-BB was found to be unaffected by IL-1?. These results indicate that the presence of IL-1? leads to impaired recruitment of osteoblasts which might influence early stages of fracture healing and could have pathological relevance for bone remodeling in inflammatory bone disease. PMID:23508571

Hengartner, Nina-Emily; Fiedler, Jörg; Ignatius, Anita; Brenner, Rolf E

2013-01-01

331

Inhibition of lysozyme by taurine dibromamine.  

PubMed

Hypobromous acid (HOBr) is a powerful oxidant produced by stimulated neutrophils and eosinophils. Taurine, a non-protein amino acid present in high amounts in the leukocytes, reacts instantaneously with HOBr leading to their haloamine derivative taurine dibromamine (Tau-NBr2). Lysozyme is a bactericidal enzyme also present in leukocytes and in secretory fluids. The inhibition of lysozyme is a pathway for bacterial proliferation in inflammatory sites. Here, we investigated the inhibition of the enzymatic activity of lysozyme when it was submitted to oxidation by Tau-NBr2. We found that the oxidation of lysozyme by Tau-NBr2 decreased its enzymatic activity in 80%, which was significant higher compared to the effect of its precursor HOBr (30%). The study and comparison of Tau-NBr2 and HOBr regarding the alterations provoked in the intrinsic fluorescence, synchronous fluorescence, resonance light scattering and near and far-UV circular dichroism spectra of lysozyme and oxidized lysozyme revealed that tryptophan residues in the active site of the protein were the main target for Tau-NBr2 and could explain its efficacy as inhibitor of lysozyme enzymatic activity. This property of Tau-NBr2 may have pathological significance, since it can be easily produced in the inflammatory sites. PMID:23590281

Petrônio, M S; Ximenes, V F

2013-11-01

332

Glycerol inhibition of ruminal lipolysis in vitro.  

PubMed

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 supplemental glycerol on rumen lipolysis, mixed populations of ruminal bacteria were incubated with 6 or 20% glycerol (vol/vol). After 48-h anaerobic incubation of mixed culture rumen fluid, rates of free fatty acid production (nmol/mL per h) for the 6 and 20% glycerol-supplemented samples were decreased by 80 and 86%, respectively, compared with rates from nonsupplemented control cultures (12.4±1.0; mean ± SE). Conversely, assay of the prominent ruminal lipase-producing bacteria Anaerovibrio lipolyticus 5S, Butyrivibrio fibrisolvens 49, and Propionibacterium species avidum and acnes revealed no effect of 2 or 10% (vol/vol) added glycerol on lipolytic activity by these organisms. Supplementing glycerol at 6% on a vol/vol basis, equivalent to supplementing glycerol at approximately 8 to 15% of diet dry matter, effectively reduced lipolysis. However, the mechanism of glycerol inhibition of ruminal lipolysis remains to be demonstrated. PMID:22916923

Edwards, H D; Anderson, R C; Miller, R K; Taylor, T M; Hardin, M D; Smith, S B; Krueger, N A; Nisbet, D J

2012-09-01

333

Ketoconazole Inhibits the Cellular Uptake of Anandamide via Inhibition of FAAH at Pharmacologically Relevant Concentrations  

PubMed Central

Background The antifungal compound ketoconazole has, in addition to its ability to interfere with fungal ergosterol synthesis, effects upon other enzymes including human CYP3A4, CYP17, lipoxygenase and thromboxane synthetase. In the present study, we have investigated whether ketoconazole affects the cellular uptake and hydrolysis of the endogenous cannabinoid receptor ligand anandamide (AEA). Methodology/Principal Findings The effects of ketoconazole upon endocannabinoid uptake were investigated using HepG2, CaCo2, PC-3 and C6 cell lines. Fatty acid amide hydrolase (FAAH) activity was measured in HepG2 cell lysates and in intact C6 cells. Ketoconazole inhibited the uptake of AEA by HepG2 cells and CaCo2 cells with IC50 values of 17 and 18 µM, respectively. In contrast, it had modest effects upon AEA uptake in PC-3 cells, which have a low expression of FAAH. In cell-free HepG2 lysates, ketoconazole inhibited FAAH activity with an IC50 value (for the inhibitable component) of 34 µM. Conclusions/Significance The present study indicates that ketoconazole can inhibit the cellular uptake of AEA at pharmacologically relevant concentrations, primarily due to its effects upon FAAH. Ketoconazole may be useful as a template for the design of dual-action FAAH/CYP17 inhibitors as a novel strategy for the treatment of prostate cancer. PMID:24466356

Björklund, Emmelie; Larsson, Therése N. L.; Jacobsson, Stig O. P.; Fowler, Christopher J.

2014-01-01

334

3-Bromopyruvate inhibits human gastric cancer tumor growth in nude mice via the inhibition of glycolysis  

PubMed Central

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.

XIAN, SHU-LIN; CAO, WEI; ZHANG, XIAO-DONG; LU, YUN-FEI

2015-01-01

335

Rethinking Inhibition Theory: On the Problematic Status of the Inhibition Theory for Forgetting  

ERIC Educational Resources Information Center

The standard textbook account of interference and forgetting is based on the assumption that retrieval of a memory trace is affected by competition by other memory traces. In recent years, a number of researchers have questioned this view and have proposed an alternative account of forgetting based on a mechanism of suppression. In this inhibition…

Raaijmakers, Jeroen G. W.; Jakab, Emoke

2013-01-01

336

Distinct Neural Correlates for Two Types of Inhibition in Bilinguals: Response Inhibition versus Interference Suppression  

ERIC Educational Resources Information Center

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…

Luk, Gigi; Anderson, John A. E.; Craik, Fergus I. M.; Grady, Cheryl; Bialystok, Ellen

2010-01-01

337

Nifuroxazide inhibits survival of multiple myeloma cells by directly inhibiting STAT3  

Microsoft Academic Search

Constitutive activation of the transcrip- tion factor STAT3 contributes to the patho- genesis of many cancers, including mul- tiple myeloma (MM). Since STAT3 is dispensable in most normal tissue, tar- geted inhibition of STAT3 is an attractive therapy for patients with these cancers. To identify STAT3 inhibitors, we devel- oped a transcriptionally based assay and screened a library of compounds

Erik A. Nelson; Sarah R. Walker; Alicia Kepich; Laurie B. Gashin; Teru Hideshima; Hiroshi Ikeda; Dharminder Chauhan; Kenneth C. Anderson; David A. Frank

2008-01-01

338

Structural requirements for inhibition of melanoma lung colonization by heparanase inhibiting species of heparin.  

PubMed

Heparanase activity correlates with metastatic potentials of lymphoma, melanoma and mammary adenocarcinoma cell lines. We investigated the ability of various modified species of heparin and size homogeneous oligosaccharides derived from depolymerized heparin to inhibit: a) heparanase-mediated degradation of heparan sulfate (HS) in the extracellular matrix (ECM) deposited by cultured endothelial cells, and b) lung colonization of B16-BL6 melanoma cells in C57BL mice. For this purpose, melanoma cells or conditioned medium were incubated with metabolically sulfate-labeled subendothelial ECM in the absence and presence of heparin, heparin fragment or nonanticoagulant species of heparin. Labeled HS degradation fragments released into the incubation medium were analyzed by gel filtration over Sepharose 6B. The B16-BL6 melanoma cells were also tested for lung colonization following their intravenous administration to C57BL mice, in the absence and presence of the various species of heparin. Inhibition of both heparanase and melanoma lung colonization depended on the size and degree of sulfation of the heparin molecule, the position of sulfate groups, and the occupancy of the N position of the hexosamines. Inhibition of heparanase was best achieved by heparin species containing 16 sugar units or more and having sulfate groups at both the N and O positions. Low sulfate oligosaccharides were less effective heparanase inhibitors than medium and high sulfate fractions of the same size saccharide. While O-desulfation abolished the heparanase inhibiting effect of heparin. O-sulfated, N-substituted (e.g., N-acetyl or N-hexanoyl) species of heparin retained a high inhibitory activity, provided that the N-substituted molecules had a molecular size of about > or = 4,000 daltons. Potent inhibitors of heparanase activity were also efficient inhibitors of tumor invasion and lung colonization. The antimetastatic and anticoagulant activities of heparin were unrelated, as indicated by using heparin fractions with high and low affinity for antithrombin III. These heparins differ about 200-fold in their anticoagulant activity, but expressed similar high antiheparanase and antimetastatic activities. It appears that heparanase-inhibiting species of heparin interfere with the passing of tumor cells across the capillary wall, as they significantly inhibited metastasis even when injected up to 3 h after lodgment. Structural requirements for inhibition of heparanase activity and lung colonization of melanoma cells by species of heparin were different from those identified for a) release of ECM-bound basic fibroblast growth factor (bFGF), and b) stimulation of bFGF receptor binding and mitogenic activity.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7744578

Bitan, M; Mohsen, M; Levi, E; Wygoda, M R; Miao, H Q; Lider, O; Svahn, C M; Ekre, H P; Ishai-Michaeli, R; Bar-Shavit, R

1995-01-01

339

Molecular mechanisms of DNA repair inhibition by caffeine  

SciTech Connect

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.

Selby, C.P.; Sancar, A. (Univ. of North Carolina School of Medicine, Chapel Hill (USA))

1990-05-01

340

Inhibition of AMPK catabolic action by GSK3  

PubMed Central

SUMMARY AMP-activated protein kinase (AMPK) regulates cellular energy homeostasis by inhibiting anabolic and activating catabolic processes. While AMPK activation has been extensively studied, mechanisms that inhibit AMPK remain elusive. Here we report that glycogen synthase kinase 3 (GSK3) inhibits AMPK function. GSK3 forms a stable complex with AMPK through interactions with the AMPK ? regulatory subunit and phosphorylates the AMPK ? catalytic subunit. This phosphorylation enhances the accessibility of the activation loop of the ? subunit to phosphatases, thereby inhibiting AMPK kinase activity. Surprisingly, PI3K-Akt signaling, which is a major anabolic signaling and normally inhibits GSK3 activity, promotes GSK3 phosphorylation and inhibition of AMPK, thus revealing how AMPK senses anabolic environments in addition to cellular energy levels. Consistently, disrupting GSK3 function within the AMPK complex sustains higher AMPK activity and cellular catabolic processes even under anabolic conditions, indicating that GSK3 acts as a critical sensor for anabolic signaling to regulate AMPK. PMID:23623684

Suzuki, Tsukasa; Bridges, Dave; Nakada, Daisuke; Skiniotis, Georgios; Morrison, Sean J.; Lin, Jiandie; Saltiel, Alan R.; Inoki, Ken

2013-01-01

341

Enhancing Allosteric Inhibition in Thermus thermophilus Phosphofructokinase.  

PubMed

The coupling between the binding of the substrate Fru-6-P and the inhibitor phospho(enol)pyruvate (PEP) in phosphofructokinase (PFK) from the extreme thermophile Thermus thermophilus is much weaker than that seen in a PFK from Bacillus stearothermophilus. From the crystal structures of Bacillus stearothermophilus PFK (BsPFK) the residues at positions 59, 158, and 215 in BsPFK are located on the path leading from the allosteric site to the nearest active site and are part of the intricate hydrogen-bonding network connecting the two sites. Substituting the corresponding residues in Thermus thermophilus PFK (TtPFK) with the amino acids found at these positions in BsPFK allowed us to enhance the allosteric inhibition by PEP by nearly 3 kcal mol(-1) (50-fold) to a value greater than or equal to the coupling observed in BsPFK. Interestingly, each single variant N59D, A158T, and S215H produced a roughly 1 kcal mol(-1) increase in coupling free energy of inhibition. The effects of these variants were essentially additive in the three combinations of double variants N59D/A158T, N59D/S215H, and A158T/S215H as well as in the triple variant N59D/A158T/S215H. Consequently, while the hydrogen-bonding network identified is likely involved in the inhibitory allosteric communication, a model requiring a linked chain of interactions connecting the sites is not supported by these data. Despite the fact that the allosteric activator of the bacterial PFK, MgADP, binds at the same allosteric site, the substitutions at positions 59, 158, and 215 do not have an equally dramatic effect on the binding affinity and the allosteric activation by MgADP. The effect of the S215H and N59D/A158T/S215H substitutions on the activation by MgADP could not be determined because of a dramatic drop in MgADP binding affinity that resulted from the S215H substitution. The single variants N59D and A158T supported binding but showed little change in the free energy of activation by MgADP compared to the wild type TtPFK. These results support previous suggestions that heterotropic inhibition and activation occur by different pathways prokaryotic PFK. PMID:25531642

McGresham, Maria S; Reinhart, Gregory D

2015-01-27

342

Ligninolytic system of Phanerochaete chrysosporium : Inhibition by o Phthalate  

Microsoft Academic Search

The degradation rate of [synthetic-14C]-lignin to 14CO2 by Phanerochaete chrysosporium in cultures buffered with 0.01 M 2,2-dimethylsuccinate (DMS) was twice that in 0.01 M o-phthalate-buffered cultures. This difference could be totally accounted for by o-phthalate inhibition of the activity of the ligninolytic system. 14CO2 production from ring-, sidechain-, and methoxyl-labeled lignins was inhibited, the degree of inhibition being dependent on

Patrick Fenn; T. Kent Kirk

1979-01-01

343

Reduced crystallization inhibition by urine from women with nephrolithiasis  

Microsoft Academic Search

Reduced crystallization inhibition by urine from women with nephrolithiasis.BackgroundHuman urine is known to inhibit growth, aggregation, nucleation, and cell adhesion of calcium oxalate monohydrate (COM) crystals, the main solid phase of human kidney stones. This study tested the hypothesis that low levels of inhibition are present in women with calcium oxalate stones and, therefore, could promote stone production.MethodsIn 17 stone-forming

John R. Asplin; Joan H. Parks; Yashushi Nakagawa; Fredric L. Coe

2002-01-01

344

High molecular weight polysaccharide that binds and inhibits virus  

SciTech Connect

This invention provides a high molecular weight polysaccharide capable of binding to and inhibiting virus and related pharmaceutical formulations and methods on inhibiting viral infectivity and/or pathogenicity, as well as immunogenic compositions. The invention further methods of inhibiting the growth of cancer cells and of ameliorating a symptom of aging. Additionally, the invention provides methods of detecting and/or quantifying and/or isolating viruses.

Konowalchuk, Thomas W

2014-01-14

345

Inhibition of cellular protein secretion by picornaviral 3A proteins  

Microsoft Academic Search

During poliovirus infection, anterograde traffic between the endoplasmic reticulum and the Golgi is inhibited due to the action of 3A, an 87 amino acid viral protein. The ability of poliovirus protein 3A to inhibit ER-to-Golgi traffic is not required for virus growth. Instead, we have suggested that the inhibition of host protein secretion, shown to reduce the secretion of interferon-?,

Sunny S. Choe; Dana A. Dodd; Karla Kirkegaard

2005-01-01

346

Anandamides inhibit binding to the muscarinic acetylcholine receptor.  

PubMed

Loss of memory and cholinergic transmission are associated with both Alzheimer's disease (AD) and marijuana use. The human brain muscarinic acetylcholine receptor (mAChR), which is involved in memory function and is inhibited by arachidonic acid, is also inhibited by anandamides. Two agonists of the cannabinoid receptor derived from arachidonic acid, anandamide (AEA) and R-methanandamide, inhibit ligand binding to the mAChR. Binding of the mAChR antagonist [3H]quinuclidinyl benzilate ([3H]QNB) is inhibited up to 89% by AEA (half-maximal inhibition at 50 microM). Binding of the more polar antagonist [N-methyl-3H]scopolamine ([3H]NMS) is inhibited by AEA up to 76% (half-maximal inhibition at 44 microM). R-methanandamide inhibits more than 90% of both [3H]QNB binding (I50 = 34 microM) and [3H]NMS binding (I50 = 15 microM) to the mAChR. Both AEA and R-methanandamide stimulate mAChR binding of the agonist [3H]oxotremorine-M at low concentrations (25-75 microM), but significantly inhibit agonist binding at higher concentrations (I50 = 150 microM). The cannabinoid antagonist SR141716A did not alter AEA or R-methanandamide inhibition of [3H]NMS binding to the mAChR, even at concentrations as high as 1 microM. Further, the cannabinoid agonist WIN 55212-2 does not alter antagonist binding to the mAChR. This demonstrates that mAChR inhibition by the anandamides is not mediated by the cannabinoid receptor. Since AEA and R-methanandamide are structurally similar to arachidonic acid, they may interact with the mAChR in a similar manner to inhibit receptor function. PMID:10691292

Lagalwar, S; Bordayo, E Z; Hoffmann, K L; Fawcett, J R; Frey, W H

1999-01-01

347

Inhibition of human lecithin cholesterol acyltransferase by monoterpenes.  

PubMed

The lecithin-cholesterol acyltransferase activity of human plasma was found to be inhibited by Rowachol, a proprietary mixture of pure monoterpenes. Menthol, the major ingredient in Rowachol (32%), and a number of other monoterpenes were found to inhibit the enzyme independently. Concentrations of monoterpenes required to achieve 50% inhibition were of the same order of magnitude as the cholesterol concentration present in the reaction mixture. PMID:6738316

Cooney, R V; Nemhauser, J; Morin, R J

1984-05-01

348

Monomers with low oxygen inhibition as enamel\\/dentin adhesives  

Microsoft Academic Search

Objectives. This study was conducted to investigate the depths of polymerization inhibition by oxygen, the shear bond strengths to enamel and dentin, and the marginal adaptation in dentin cavities of experimental adhesives containing BisGMA\\/HEMA or mixtures of low-inhibition BisGMA-dicarbonate with HEMA or with HEMA-carbonate at ratios of 100\\/0, 80\\/20, 60\\/40, 50\\/50, and 40\\/60 by weight.Methods. The inhibition layer thickness was

Werner J. Finger; Kyoung-Sun Lee; Wolfgang Podszun

1996-01-01

349

Recurrent inhibition of interneurones monosynaptically activated from group Ia afferents  

PubMed Central

1. Interneurones monosynaptically excited from large muscle spindle (Ia) afferents and inhibited from motor axon collaterals were searched for in the lumbar spinal cord of the cat. 2. Monosynaptic Ia excitation was found in sixty-seven of sixty-nine interneurones inhibited by antidromic volleys. These interneurones were excited from Ia afferents from one or a few muscles (mainly close synergists). Volleys in high threshold muscle and skin afferents (FRA) evoked polysynaptic excitation or inhibition. Weak inhibition from Ia afferents (from antagonists to those giving Ia excitation) was seen in a few cells. Monosynaptic excitation was evoked from the ventral quadrant of the spinal cord and polysynaptic excitation from the dorsal quadrant. 3. Inhibition from motor axon collaterals was evoked with a latency (1·2-2·0 msec) suggesting a disynaptic linkage and had the same time course as in motoneurones. It prevented synaptic activation of 60% of interneurones and decreased the firing index and delayed generation of spikes in the remaining. 4. The interneurones with convergence of monosynaptic Ia excitation and inhibition from motor axon collaterals were found in the ventral horn dorsomedial to motor nuclei. No inhibition by antidromic volleys could be detected in interneurones located in intermediate nucleus and activated monosynaptically from Ia, Ib, group I or cutaneous afferents. 5. It was concluded that the ventral Ia interneurones inhibited by volleys in recurrent motor axon collaterals mediate the reciprocal Ia inhibition to motoneurones. PMID:4253675

Hultborn, H.; Jankowska, El?bieta; Lindström, S.

1971-01-01

350

The relationship between rhythmic synchronization and response inhibition.  

E-print Network

?????Temporal preparation and impulsivity are sharing two common cognitive processes: time perception and response inhibition. Rhythmic synchronization can be regarded as a specific paradigm of… (more)

Sze, Hoi-yee, Esther.

2011-01-01

351

Inhibition of Photosystem II in Isolated Chloroplasts by Lead 1  

PubMed Central

Inhibition of photosynthetic electron transport in isolated chloroplasts by lead salts has been demonstrated. Photosystem I activity, as measured by electron transfer from dichlorophenol indophenol to methylviologen, was not reduced by such treatment. However, photosystem II was inhibited by lead salts when electron flow was measured from water to methylviologen and Hill reaction or by chlorophyll fluorescence. Fluorescence induction curves indicated the primary site of inhibition was on the oxidizing side of photosystem II. That this site was between the primary electron donor of photosystem II and the site of water oxidation could be demonstrated by hydroxylamine restoration of normal fluorescence following lead inhibition. PMID:16658055

Miles, C. D.; Brandle, J. R.; Daniel, D. J.; Chu-Der, O.; Schnare, P. D.; Uhlik, D. J.

1972-01-01

352

Timing of growth inhibition following shoot inversion in Pharbitis nil  

NASA Technical Reports Server (NTRS)

Shoot inversion in Pharbitis nil results in the enhancement of ethylene production and in the inhibition of elongation in the growth zone of the inverted shoot. The initial increase in ethylene production previously was detected within 2 to 2.75 hours after inversion. In the present study, the initial inhibition of shoot elongation was detected within 1.5 to 4 hours with a weighted mean of 2.4 hours. Ethylene treatment of upright shoots inhibited elongation in 1.5 hours. A cause and effect relationship between shoot inversion-enhanced ethylene production and inhibition of elongation cannot be excluded.

Abdel-Rahman, A. M.; Cline, M. G.

1989-01-01

353

Inhibition and mechanism of HDAC8 revisited.  

PubMed

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

Chen, Kai; Zhang, Xiaoxiao; Wu, Yun-Dong; Wiest, Olaf

2014-08-20

354

Inhibiting homologous recombination for cancer therapy  

PubMed Central

We review the rationale for seeking inhibitors of homologous recombination (HR) repair for use in cancer therapy. Cells use HR as one way to repair DNA double-strand breaks that arise directly from treatments such as radiotherapy, or indirectly during replication when forks encounter other damage. HR occurs during the S and G2 phases of the cell cycle and is therefore more significant in dividing cancer cells than in non-dividing cells of healthy tissue, giving a potential therapeutic advantage to inhibiting the process. Also, some tumors consist of cells that are defective in other DNA repair pathways, and such cells may be sensitive to HR repair inhibitors because of synthetic lethality, in which blocking two alternative pathways that a cell can use to reach a needed end-point has a much bigger impact than blocking either pathway alone. We review strategies for identifying HR inhibitors and discuss current progress. PMID:22336907

Chernikova, Sophia B; Game, John C

2012-01-01

355

Meaning Inhibition and Sentence Processing in Chinese.  

PubMed

The present study examined the inhibitory processes of spoken word recognition of Chinese homophones during sentence processing, using a standard cross-modal naming experiment with an innovative design and materials construction. Results confirmed that (1) preceding sentence context has exerted an early effect on disambiguating among different alternative meanings of the homophones; (2) the contextually inappropriate meanings of the ambiguous word were inhibited rapidly during sentence processing; and (3) the present results also demonstrated that the inhibitory mechanism could be sustained to a longer duration following the occurrence of the ambiguous word (homophone). Finally, all these results clearly revealed the dynamics of interaction of context effects and spoken word recognition processes. PMID:25015026

Yip, Michael C W

2014-07-12

356

Inhibition of strigolactones promotes adventitious root formation  

PubMed Central

Roots that form from non-root tissues (adventitious roots) are crucial for cutting propagation in the forestry and horticulture industries. Strigolactone has been demonstrated to be an important regulator of these roots in both Arabidopsis and pea using strigolactone deficient mutants and exogenous hormone applications. Strigolactones are produced from a carotenoid precursor which can be blocked using the widely available but broad terpenoid biosynthesis blocker, fluridone. We demonstrate here that fluridone can be used to promote adventitious rooting in the model species Pisum sativum (pea). In addition, in the garden species Plumbago auriculata and Jasminium polyanthum fluridone was equally as successful at promoting roots as a commercial rooting compound containing NAA and IBA. Our findings demonstrate that inhibition of strigolactone signaling has the potential to be used to improve adventitious rooting in commercially relevant species. PMID:22580687

Beveridge, Christine A.; Geelen, Danny

2012-01-01

357

The IFITM proteins inhibit HIV-1 infection.  

PubMed

Type I interferon protects cells from virus infection through the induction of a group of genes collectively named interferon-stimulated genes (ISGs). In this study, we utilized short hairpin RNA (shRNA) to deplete ISGs in SupT1 cells in order to identify ISGs that suppress the production of human immunodeficiency virus type 1 (HIV-1). Among the ISG candidates thus identified were interferon-induced transmembrane (IFITM) proteins, including IFITM1, IFITM2, and IFITM3, that potently inhibit HIV-1 replication at least partially through interfering with virus entry. Further mutagenesis analysis shows that the intracellular region, rather than the N- and C-terminal extracellular domains, is essential for the antiviral activity of IFITM1. Altogether, these data suggest that the IFITM proteins serve as important components of the innate immune system to restrict HIV-1 infection. PMID:21177806

Lu, Jennifer; Pan, Qinghua; Rong, Liwei; He, Wei; Liu, Shan-Lu; Liang, Chen

2011-03-01

358

PI3K? Inhibitors That Inhibit Metastasis  

PubMed Central

Previous genetic analyses have suggested that mutations of the genes encoding PI3K? facilitate invasion and metastasis but have less effect on primary tumor growth. These findings have major implications for therapeutics but have not been factored into pre-clinical drug development designs. Here we show that the inhibition of PI3K? by newly designed small molecule inhibitors prevented metastasis formation in mice but had much less effect on the growth of subcutaneous xenografts or primary intra-abdominal tumors. These data support the idea that PI3K? plays an important role in the metastatic process and suggest a more informed strategy for selecting drugs worthy of further development for clinical application. PMID:21179398

Schmidt-Kittler, Oleg; Zhu, Jiuxiang; Yang, Jian; Liu, Guosheng; Hendricks, William; Lengauer, Christoph; Gabelli, Sandra B.; Kinzler, Kenneth W.; Vogelstein, Bert; Huso, David L.; Zhou, Shibin

2010-01-01

359

Cimetidine inhibits angiogenesis and suppresses tumor growth.  

PubMed

Cimetidine, a histamine type-2 receptor antagonist, has been reported to improve survival of patients with cancers. However, the exact mechanisms by which cimetidine suppresses development of cancers remain to be elucidated. Solid tumors require neovascularization for their growth. Here, we investigated the effects of cimetidine on tumor growth and angiogenesis. Syngeneic colon cancer cells, CMT93 cells, were inoculated into the subcutaneous space of C57BL/6 mice. Mice were treated with either saline or cimetidine. Tumor size was measured everyday and angiogenesis was evaluated histologically. Cimetidine markedly suppressed tumor growth with reduced neovascularization in the tumor. Cimetidine had no effect on proliferation of CMT93 cells in vitro. Vascular endothelial growth factor production by cancer cells was not affected by cimetidine, while vascular-like tube formation by endothelial cells in vitro was significantly impaired in the presence of cimetidine. Our findings suggest that cimetidine suppresses tumor growth, at least in part, by inhibiting tumor-associated angiogenesis. PMID:15740937

Natori, Takeshi; Sata, Masataka; Nagai, Ryozo; Makuuchi, Masatoshi

2005-01-01

360

Selenium nanoparticles inhibit Staphylococcus aureus growth  

PubMed Central

Staphylococcus aureus is a key bacterium commonly found in numerous infections. S. aureus infections are difficult to treat due to their biofilm formation and documented antibiotic resistance. While selenium has been used for a wide range of applications including anticancer applications, the effects of selenium nanoparticles on microorganisms remain largely unknown to date. The objective of this in vitro study was thus to examine the growth of S. aureus in the presence of selenium nanoparticles. Results of this study provided the first evidence of strongly inhibited growth of S. aureus in the presence of selenium nanoparticles after 3, 4, and 5 hours at 7.8, 15.5, and 31 ?g/mL. The percentage of live bacteria also decreased in the presence of selenium nanoparticles. Therefore, this study suggests that selenium nanoparticles may be used to effectively prevent and treat S. aureus infections and thus should be further studied for such applications. PMID:21845045

Tran, Phong A; Webster, Thomas J

2011-01-01

361

Ubiquitin acetylation inhibits polyubiquitin chain elongation.  

PubMed

Ubiquitylation is a versatile post-translational modification (PTM). The diversity of ubiquitylation topologies, which encompasses different chain lengths and linkages, underlies its widespread cellular roles. Here, we show that endogenous ubiquitin is acetylated at lysine (K)-6 (AcK6) or K48. Acetylated ubiquitin does not affect substrate monoubiquitylation, but inhibits K11-, K48-, and K63-linked polyubiquitin chain elongation by several E2 enzymes in vitro. In cells, AcK6-mimetic ubiquitin stabilizes the monoubiquitylation of histone H2B-which we identify as an endogenous substrate of acetylated ubiquitin-and of artificial ubiquitin fusion degradation substrates. These results characterize a mechanism whereby ubiquitin, itself a PTM, is subject to another PTM to modulate mono- and polyubiquitylation, thus adding a new regulatory layer to ubiquitin biology. PMID:25527407

Ohtake, Fumiaki; Saeki, Yasushi; Sakamoto, Kensaku; Ohtake, Kazumasa; Nishikawa, Hiroyuki; Tsuchiya, Hikaru; Ohta, Tomohiko; Tanaka, Keiji; Kanno, Jun

2015-02-01

362

Cartilage proteoglycans inhibit fibronectin-mediated adhesion  

NASA Astrophysics Data System (ADS)

Normal tissues and organs show, on histological examination, a pattern of cellular and acellular zones that is characteristic and unique for each organ or tissue. This pattern is maintained in health but is sometimes destroyed by disease. For example, in mobile joints, the articular surfaces consist of relatively acellular hyaline cartilage, and the joint space is enclosed by a capsule of loose connective tissue with a lining of fibroblasts and macrophages. In the normal joint these cells are confined to the synovial lining and the articular surface remains acellular. In in vitro culture, macrophages and their precursor monocytes are very adhesive, and fibroblasts can migrate and overgrow surfaces such as collagen or plastic used for tissue culture. The fibroblasts adhere to collagen by means of fibronectin, which they synthesize and secrete1. Because the collagen of cartilage is capable of binding serum fibronectin2 and fibronectin is present in cartilage during its development3, these cells should, in theory, slowly migrate from the synovial lining to the articular surface. It is their absence from the articular cartilage in normal circumstances, and then presence in such pathological states as rheumatoid arthritis, that is striking. We therefore set out to determine whether a component of cartilage could prevent fibroblast adherence in a defined adhesion assay. As normal cartilage is composed of 50% proteoglycans and 50% collagen by dry weight4, we tested the possibility that the proteoglycans in cartilage inhibit fibroblast adhesion to collagen. We present here evidence that fibroblast spreading and adhesion to collagenous substrates is inhibited by cartilage proteoglycans.

Rich, A. M.; Pearlstein, E.; Weissmann, G.; Hoffstein, S. T.

1981-09-01

363

Nitric oxide synthases: structure, function and inhibition.  

PubMed Central

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

Alderton, W K; Cooper, C E; Knowles, R G

2001-01-01

364

Exploring Mycobacterium avium inhibition by macrocyclic compounds.  

PubMed

Derivatives of synthetic macrocyclic compounds, MCC, 12- and 14-membered tetraazamacrocycles with N-pendant arms, such as N-methyl (Mepy14), N-acetate (DOTA, TETA and ac3py14) and N-methylphosphonate (DOTP) groups, were investigated in terms of their in vitro activity against Mycobacterium avium and for intracellular clearance, using the murine macrophage cell line J-774. Perspective results on a laboratory strain, of opaque morphology, showed in vitro activity with varying inhibitory patterns from one compound to another. The most active compounds, such as TETA, presented N-acetate pendant arms. Inhibition levels of 90% and above were obtained at 50 mg/l. Inhibition was confirmed with both the free compound and its iron(III) complex for DOTP, Mepy14, ac3py14, and TETA. However, with DOTA, no inhibitory effect was observed for the iron(III) complex, suggesting that chelation was at the origin of the inhibitory effect or that the donor atoms of the ligand were strongly involved. Nevertheless, simple experiments indicated that ferric ion might not be responsible for this reversed activity. Intracellular activity using 50 mg/l of TETA confirmed in vitro results with the laboratory strain. Results expressed as relative growth (%), of the drug-containing samples compared to control samples ranged from 2 to 123% (growth promotion) with no apparent relationship between inhibitory activity and the colony morphology of the strains. These studies showed that the evaluation of synthetic macrocycles may be relevant in development of a new family of compounds for use against M. avium infections. PMID:16024228

David, Suzana; Barros, Vanessa; Passos Guerra, Krassimira; Delgado, Rita

2005-11-01

365

Structural basis of kynurenine 3-monooxygenase inhibition  

PubMed Central

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

Amaral, Marta; Levy, Colin; Heyes, Derren J.; Lafite, Pierre; Outeiro, Tiago F.; Giorgini, Flaviano; Leys, David; Scrutton, Nigel S.

2013-01-01

366

Arginase II inhibition prevents nitrate tolerance  

PubMed Central

BACKGROUND AND PURPOSE Nitrate tolerance, the loss of vascular responsiveness with continued use of nitrates, remains incompletely understood and is a limitation of these therapeutic agents. Vascular superoxide, generated by uncoupled endothelial NOS (eNOS), may play a role. As arginase competes with eNOS for L-arginine and may exacerbate the production of reactive oxygen species (ROS), we hypothesized that arginase inhibition might reduce nitrate tolerance. EXPERIMENTAL APPROACH Vasodilator responses were measured in aorta from C57Bl/6 and arginase II knockout (argII –/–) mice using myography. Uncoupling of eNOS, determined as eNOS monomer : dimer ratio, was assessed using low-temperature SDS-PAGE and ROS levels were measured using L-012 and lucigenin-enhanced chemiluminescence. KEY RESULTS Repeated application of glyceryl trinitrate (GTN) on aorta isolated from C57Bl/6 mice produced a 32-fold rightward shift of the concentration–response curve. However this rightward shift (or resultant tolerance) was not observed in the presence of the arginase inhibitor (s)-(2-boronethyl)-L-cysteine HCl (BEC; 100 µM) nor in aorta isolated from argII –/– mice. Similar findings were obtained after inducing nitrate tolerance in vivo. Repeated administration of GTN in human umbilical vein endothelial cells induced uncoupling of eNOS from its dimeric state and increased ROS levels, which were reduced with arginase inhibition and exogenous L-arginine. Aortae from GTN tolerant C57Bl/6 mice exhibited increased arginase activity and ROS production, whereas vessels from argII –/– mice did not. CONCLUSION AND IMPLICATIONS Arginase II removal prevents nitrate tolerance. This may be due to decreased uncoupling of eNOS and consequent ROS production. PMID:22288373

Khong, SML; Andrews, KL; Huynh, NN; Venardos, K; Aprico, A; Michell, DL; Zarei, M; Moe, KT; Dusting, GJ; Kaye, DM; Chin-Dusting, JPF

2012-01-01

367

Metalloporphyrins inhibit beta-hematin (hemozoin) formation.  

PubMed

Metal-substituted protoporphyrin IXs (Cr(III)PPIX (1), Co(III)PPIX (2), Mn(III)PPIX (3), Cu(II)PPIX (4), Mg(II)PPIX (5), Zn(II)PPIX (6), and Sn(IV)PPIX (7)) act as inhibitors to beta-hematin (hemozoin) formation, a critical detoxification biopolymer of malarial parasites. The central metal ion plays a significant role in the efficacy of the metalloprotoporphyrins to inhibit beta-hematin formation. The efficacy of these compounds correlates well with the water exchange rate for the octahedral aqua complexes of the porphyrin's central metal ion. Under these in vitro reaction conditions, metalloporphyrins 5, 6 and 7 are as much as six times more efficacious than the free ligand protoporphyrin IX in preventing beta-hematin formation and four times as efficacious as chloroquine, while metalloporphyrins 3 and 4 are three to four times more effective at preventing beta-hematin formation than the free protoporphyrin IX base. In contrast, the relatively exchange inert metalloporphyrins 1 and 2 are only as efficacious as the free ligand and only two-thirds as effective as chloroquine. Aggregation studies of the heme:MPPIX using UV-Vis and fluorescence spectroscopies are indicative of the formation of pi-pi hetero-metalloporphyrin assemblies. Thus, hemozoin inhibition is likely prevented by the formation of heme:MPPIX complexes through pi-stacking interactions. The ramifications of such hetero-metalloporphyrin assemblies, in the context of the emerging structural picture of hemozoin, are discussed. PMID:10766333

Cole, K A; Ziegler, J; Evans, C A; Wright, D W

2000-01-30

368

From autoinhibition to inhibition in trans: the Raf-1 regulatory domain inhibits Rok-? kinase activity  

PubMed Central

The activity of Raf-1 and Rok-? kinases is regulated by intramolecular binding of the regulatory region to the kinase domain. Autoinhibition is relieved upon binding to the small guanosine triphosphatases Ras and Rho. Downstream of Ras, Raf-1 promotes migration and tumorigenesis by antagonizing Rok-?, but the underlying mechanism is unknown. In this study, we show that Rok-? inhibition by Raf-1 relies on an intermolecular interaction between the Rok-? kinase domain and the cysteine-rich Raf-1 regulatory domain (Raf-1reg), which is similar to Rok-?'s own autoinhibitory region. Thus, Raf-1 mediates Rok-? inhibition in trans, which is a new concept in kinase regulation. This mechanism is physiologically relevant because Raf-1reg is sufficient to rescue all Rok-?–dependent defects of Raf-1–deficient cells. Downstream of Ras and Rho, the Raf-1–Rok-? interaction represents a novel paradigm of pathway cross talk that contributes to tumorigenesis and cell motility. PMID:19948477

Niault, Théodora; Sobczak, Izabela; Meissl, Katrin; Weitsman, Gregory; Piazzolla, Daniela; Maurer, Gabriele; Kern, Florian; Ehrenreiter, Karin; Hamerl, Matthias; Moarefi, Ismail; Leung, Thomas; Carugo, Oliviero; Ng, Tony

2009-01-01

369

Inhibition of aldose reductase by dietary antioxidant curcumin: mechanism of inhibition, specificity and significance.  

PubMed

Accumulation of intracellular sorbitol due to increased aldose reductase (ALR2) activity has been implicated in the development of various secondary complications of diabetes. In this study we show that curcumin inhibits ALR2 with an IC(50) of 10 microM in a non-competitive manner, but is a poor inhibitor of closely-related members of the aldo-keto reductase superfamily, particularly aldehyde reductase. Results from molecular docking studies are consistent with the pattern of inhibition of ALR2 by curcumin and its specificity. Moreover, curcumin is able to suppress sorbitol accumulation in human erythrocytes under high glucose conditions, demonstrating an in vivo potential of curcumin to prevent sorbitol accumulation. These results suggest that curcumin holds promise as an agent to prevent or treat diabetic complications. PMID:19850041

Muthenna, P; Suryanarayana, P; Gunda, Shravan K; Petrash, J Mark; Reddy, G Bhanuprakash

2009-11-19

370

Transfection of the mullerian inhibiting substance gene inhibits local and metastatic tumor-growth.  

PubMed

Mullerian Inhibiting Substance (MIS), a gonadal growth factor important in sexual differentiation, has antiproliferative activity against several human carcinoma cell lines. In this study, we examine the effect of MIS-transfection on the growth characteristics of Chinese hamster ovary (CHO) and human ocular melanoma (OM431) cells, compared to wild-type lines and a CHO line transfected with a noncleavable, inactive MIS mutant. MIS-transfection inhibited proliferation of CHO cells in double-layer agarose, tumor spheroid, and murine subrenal capsule assays, as well as growth of CHO and OM431 cells in pulmonary metastasis studies. These results anticipate further study of targeted gene therapy of certain human tumors with MIS gene constructs. PMID:21573527

Boveri, J; Parry, R; Ruffin, W; Gustafson, M; Lee, K; He, W; Donahoe, P

1993-02-01

371

Inhibition of Escherichia coli ATP synthase by amphibian antimicrobial peptides.  

PubMed

Previously melittin, the alpha-helical basic honey bee venom peptide, was shown to inhibit F(1)-ATPase by binding at the beta-subunit DELSEED motif of F(1)F(o)-ATP synthase. Herein, we present the inhibitory effects of the basic alpha-helical amphibian antimicrobial peptides, ascaphin-8, aurein 2.2, aurein 2.3, carein 1.8, carein 1.9, citropin 1.1, dermaseptin, maculatin 1.1, maganin II, MRP, or XT-7, on purified F(1) and membrane bound F(1)F(0)Escherichia coli ATP synthase. We found that the extent of inhibition by amphibian peptides is variable. Whereas MRP-amide inhibited ATPase essentially completely (approximately 96% inhibition), carein 1.8 did not inhibit at all (0% inhibition). Inhibition by other peptides was partial with a range of approximately 13-70%. MRP-amide was also the most potent inhibitor on molar scale (IC(50) approximately 3.25 microM). Presence of an amide group at the c-terminal of peptides was found to be critical in exerting potent inhibition of ATP synthase ( approximately 20-40% additional inhibition). Inhibition was fully reversible and found to be identical in both F(1)F(0) membrane preparations as well as in isolated purified F(1). Interestingly, growth of E. coli was abrogated in the presence of ascaphin-8, aurein 2.2, aurein 2.3, citropin 1.1, dermaseptin, magainin II-amide, MRP, MRP-amide, melittin, or melittin-amide but was unaffected in the presence of carein 1.8, carein 1.9, maculatin 1.1, magainin II, or XT-7. Hence inhibition of F(1)-ATPase and E. coli cell growth by amphibian antimicrobial peptides suggests that their antimicrobial/anticancer properties are in part linked to their actions on ATP synthase. PMID:20100509

Laughlin, Thomas F; Ahmad, Zulfiqar

2010-04-01

372

Inhibiting the HSP90 chaperone destabilizes macrophage migration inhibitory factor and thereby inhibits breast tumor progression  

PubMed Central

Intracellular macrophage migration inhibitory factor (MIF) often becomes stabilized in human cancer cells. MIF can promote tumor cell survival, and elevated MIF protein correlates with tumor aggressiveness and poor prognosis. However, the molecular mechanism facilitating MIF stabilization in tumors is not understood. We show that the tumor-activated HSP90 chaperone complex protects MIF from degradation. Pharmacological inhibition of HSP90 activity, or siRNA-mediated knockdown of HSP90 or HDAC6, destabilizes MIF in a variety of human cancer cells. The HSP90-associated E3 ubiquitin ligase CHIP mediates the ensuing proteasome-dependent MIF degradation. Cancer cells contain constitutive endogenous MIF–HSP90 complexes. siRNA-mediated MIF knockdown inhibits proliferation and triggers apoptosis of cultured human cancer cells, whereas HSP90 inhibitor-induced apoptosis is overridden by ectopic MIF expression. In the ErbB2 transgenic model of human HER2-positive breast cancer, genetic ablation of MIF delays tumor progression and prolongs overall survival of mice. Systemic treatment with the HSP90 inhibitor 17AAG reduces MIF expression and blocks growth of MIF-expressing, but not MIF-deficient, tumors. Together, these findings identify MIF as a novel HSP90 client and suggest that HSP90 inhibitors inhibit ErbB2-driven breast tumor growth at least in part by destabilizing MIF. PMID:22271573

Schulz, Ramona; Marchenko, Natalia D.; Holembowski, Lena; Fingerle-Rowson, Günter; Pesic, Marina; Zender, Lars; Dobbelstein, Matthias

2012-01-01

373

Tumor suppressor XAF1 induces apoptosis, inhibits angiogenesis and inhibits tumor growth in hepatocellular carcinoma  

PubMed Central

X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1), a XIAP-binding protein, is a tumor suppressor gene. XAF1 was silent or expressed lowly in most human malignant tumors. However, the role of XAF1 in hepatocellular carcinoma (HCC) remains unknown. In this study, we investigated the effect of XAF1 on tumor growth and angiogenesis in hepatocellular cancer cells. Our results showed that XAF1 expression was lower in HCC cell lines SMMC-7721, Hep G2 and BEL-7404 and liver cancer tissues than that in paired non-cancer liver tissues. Adenovirus-mediated XAF1 expression (Ad5/F35-XAF1) significantly inhibited cell proliferation and induced apoptosis in HCC cells in dose- and time- dependent manners. Infection of Ad5/F35-XAF1 induced cleavage of caspase -3, -8, -9 and PARP in HCC cells. Furthermore, Ad5/F35-XAF1 treatment significantly suppressed tumor growth in a xenograft model of liver cancer cells. Western Blot and immunohistochemistry staining showed that Ad5/F35-XAF1 treatment suppressed expression of vascular endothelial growth factor (VEGF), which is associated with tumor angiogenesis, in cancer cells and xenograft tumor tissues. Moreover, Ad5/F35-XAF1 treatment prolonged the survival of tumor-bearing mice. Our results demonstrate that XAF1 inhibits tumor growth by inducing apoptosis and inhibiting tumor angiogenesis. XAF1 may be a promising target for liver cancer treatment. PMID:24980821

Zhu, Li Ming; Shi, Dong Mei; Dai, Qiang; Cheng, Xiao Jiao; Yao, Wei Yan; Sun, Ping Hu; Ding, Yan Fei; Qiao, Min Min; Wu, Yun Lin; Jiang, Shi Hu; Tu, Shui Ping

2014-01-01

374

Method for inhibiting gum formation in liquid hydrocarbon mediums  

SciTech Connect

This patent describes a method of inhibiting the formation of gum and sediment in a liquid hydrocarbonaceous medium. It comprises: adding to the medium an inhibiting amount of an alkyl 1,2-dihydroquinoline or polymerized alkyl 1,2-dihydroquinoline.

Reid, D.K.

1990-07-17

375

Forensic implications of PCR inhibition—A review  

Microsoft Academic Search

Polymerase chain reaction (PCR) is currently the method of choice for the identification of human remains in forensic coursework. DNA samples from crime scenes often contain co-purified impurities which inhibit PCR. PCR inhibition is the most common cause of PCR failure when adequate copies of DNA are present. Inhibitors have been routinely reported in forensic investigations of DNA extracted from

Reza Alaeddini

376

Forward and back: motifs of inhibition in olfactory processing.  

PubMed

The remarkable performance of the olfactory system in classifying and categorizing the complex olfactory environment is built upon several basic neural circuit motifs. These include forms of inhibition that may play comparable roles in widely divergent species. In this issue of Neuron, a new study by Stokes and Isaacson sheds light on how elementary types of inhibition dynamically interact. PMID:20696373

Bazhenov, Maxim; Stopfer, Mark

2010-08-12

377

A Nonantibiotic Chemically Modified Tetracycline (CMT3) Inhibits Intimal Thickening  

Microsoft Academic Search

Recent research has shown that the tetracycline anti- biotics are pluripotent drugs that inhibit the activity of matrix metalloproteinases (MMPs) and affect many cellular functions including proliferation, migration, and matrix remodeling. We have shown that doxycy- cline inhibits MMP activity and intimal thickening after injury of the rat carotid artery, however we do not know whether these effects are because

Muzharul M. Islam; Christopher D. Franco; David W. Courtman; Michelle P. Bendeck

2003-01-01

378

Inhibition of dynamin completely blocks compensatory synaptic vesicle endocytosis  

E-print Network

Inhibition of dynamin completely blocks compensatory synaptic vesicle endocytosis A. Jamila Newton vesicle endocytosis remains unclear. Here, we have tested the role of dynamin in synaptic vesicle endocytosis by using a small molecule called dynasore, which rapidly inhibits the GTPase activity of dynamin

Kirchhausen, Tomas

379

Autonomic Cardiovascular Responses to Heme Oxygenase Inhibition in Conscious Rats  

Microsoft Academic Search

Carbon monoxide (CO) is produced in the course of heme degradation from biliverdin by heme oxygenase (HO) in various tissues, including the central nervous system. Recent studies suggest the inhibition of HO activity increases arterial pressure mediated by the autonomic nervous system. The present study was designed to investigate the autonomic regulation of cardiovascular responses to inhibition of endogenous CO

Haruhisa Hirakawa; Yoshiaki Hayashida

2010-01-01

380

The Crossed Response Inhibition Task in Parkinson's Disease: Disinhibition Hyperkinesia  

Microsoft Academic Search

Patients with Parkinson's disease (PD) have dysfunction in frontal-basal ganglia networks. Many of these patients have difficulties with mental processing speed, response inhibition, and shifting between different conceptual sets, suggesting frontal-executive dysfunction. Since frontal lobe dysfunction is associated with disengagement deficits such as perseveration and echopraxia we wanted to learn if patients with PD demonstrated defective response inhibition. Using a

Gregory P. Crucian; Kenneth Heilman; Elia Junco; Michael Maraist; William E. Owens; Kelly D. Foote; Michael S. Okun

2007-01-01

381

A sulfated carbohydrate epitope inhibits axon regeneration after injury  

E-print Network

A sulfated carbohydrate epitope inhibits axon regeneration after injury Joshua M. Browna,1 , Jiang demonstrate that a sugar epitope on CSPGs, chondroitin sulfate-E (CS-E), potently inhibits axon growth and stimulated axon regeneration in vivo. These results demonstrate that a specific sugar epitope within

Hsieh-Wilson, Linda

382

Secondary School Students' Views of Inhibiting Factors in Seeking Counselling  

ERIC Educational Resources Information Center

This study examines secondary school students' perceptions of inhibiting factors in seeking counselling. Responses to a questionnaire completed by 1346 secondary school students were analysed using quantitative and qualitative methods. Exploratory factor analysis highlighted that within 21 pre-defined inhibiting factors, items loaded strongly on…

Chan, Stephanie; Quinn, Philip

2012-01-01

383

Stuttering Inhibition via Altered Auditory Feedback during Scripted Telephone Conversations  

ERIC Educational Resources Information Center

Background: Overt stuttering is inhibited by approximately 80% when people who stutter read aloud as they hear an altered form of their speech feedback to them. However, levels of stuttering inhibition vary from 60% to 100% depending on speaking situation and signal presentation. For example, binaural presentations of delayed auditory feedback…

Hudock, Daniel; Kalinowski, Joseph

2014-01-01

384

The Affective Consequences of Cognitive Inhibition: Devaluation or Neutralization?  

ERIC Educational Resources Information Center

Affective evaluations of previously ignored visual stimuli are more negative than those of novel items or prior targets of attention or response. This has been taken as evidence that inhibition has negative affective consequences. But inhibition could act instead to attenuate or "neutralize" preexisting affective salience, predicting opposite…

Frischen, Alexandra; Ferrey, Anne E.; Burt, Dustin H. R.; Pistchik, Meghan; Fenske, Mark J.

2012-01-01

385

Rosiglitazone Inhibits Proliferation, Motility, and Matrix Metalloproteinase Production in Keratinocytes  

Microsoft Academic Search

This study was undertaken to evaluate the effects of thiazolidinediones (TZD) on keratinocyte proliferation, motility, and matrix metalloproteinase (MMP) production. Rosiglitazone (a potent TZD) inhibited both proliferation and motility as well as elaboration of MMP-1 and MMP-9. Inhibition was obtained with keratinocytes in monolayer culture and human skin in organ culture. There were significant concentration–response differences in sensitivity of the

Narasimharao Bhagavathula; Kamalakar C. Nerusu; Ashish Lal; Charles N. Ellis; Amar Chittiboyina; Mitchell A. Avery; Christopher I. Ho; Stephen C. Benson; Harrihar A. Pershadsingh; Theodore W. Kurtz; James Varani

2004-01-01

386

Metformin inhibits the inflammatory response associated with cellular transformation and  

E-print Network

Metformin inhibits the inflammatory response associated with cellular transformation and cancer, December 4, 2012 (sent for review October 18, 2012) Metformin, the first-line drug for treating diabetes. In a Src-inducible model of cellular transforma- tion, metformin inhibits the earliest known step

387

Effect of Heparin on Protein Aggregation: Inhibition versus Yisheng Xu,  

E-print Network

Effect of Heparin on Protein Aggregation: Inhibition versus Promotion Yisheng Xu, Daniel Seeman: The effect of heparin on both native and denatured protein aggregation was investigated by turbidim- etry and dynamic light scattering (DLS). Turbidimetric data show that heparin is capable of inhibiting

Dubin, Paul D.

388

Extracts of ginkgo biloba leaves inhibit monoamine oxidase  

Microsoft Academic Search

Extracts of Ginkgo biloba leaves produce reversible inhibition of rat brain monoamine oxidase (MAO). Both MAO-A and -B types were inhibited to a similar extent. The MAO inhibitory compound(s) were present in dried or fresh Ginkgo biloba leaves as well as in commercially available capsules of Ginkgo biloba and appear to be heat stable with relatively low molecular weight. MAO

Helen L. White; Philip W. Scates; Barrett R. Cooper

1996-01-01

389

Differences between Somatic and Dendritic Inhibition in the Hippocampus  

Microsoft Academic Search

Hippocampal synaptic inhibition is mediated by distinct groups of inhibitory cells. Some contact pyramidal cells perisomatically, while others terminate exclusively on their dendrites. We examined perisomatic and dendritic inhibition by recording from CA3 inhibitory and pyramidal cells and injecting biocytin to visualize both cells in light and electron microscopy. Single perisomatic inhibitory cells made 2–6 terminals clustered around the soma

Richard Miles; Katalin Tóth; Attila I Gulyás; Norbert Hájos; Tamas F Freund

1996-01-01

390

Childhood Behavioral Inhibition and Maternal Symptoms of Depression  

Microsoft Academic Search

Background: The significance of behavioral inhibition in the second year of life for the development of social phobia in later childhood was the incentive to explore whether maternal postnatal psychopathology is a predictor for behavioral inhibition in the offspring. Method: 101 mother-infant pairs were recruited from local obstetric units and examined for maternal psychopathology by the Symptom Checklist and the

E. Moehler; J. Kagan; P. Parzer; R. Brunner; C. Reck; A. Wiebel; L. Poustka; F. Resch

2007-01-01

391

Polygalacturonase-inhibiting proteins in defense against phytopathogenic fungi  

Microsoft Academic Search

Polygalacturonase-inhibiting proteins (PGIPs) are ubiquitous plant cell wall proteins that are directed against fungal polygalacturonases (PGs), which are important pathogenicity factors. The inhibiting activity of PGIPs directly reduces the aggressive potential of PGs. In addition, it causes PGs to form more long-chain oligogalacturonides that are able to induce defense responses, thereby indirectly contributing to the plant defense. Recent evidence demonstrates

Giulia De Lorenzo; Simone Ferrari

2002-01-01

392

A MATHEMATICAL MODEL OF HPPD INHIBITION. Mathematical Medicine Study Group  

E-print Network

A MATHEMATICAL MODEL OF HPPD INHIBITION. Mathematical Medicine Study Group September 2011 G. Derks with a safe mammalian toxicity profile. In laboratory animals HPPD inhibition leads to the elevation of plasma- centration of tyrosine that accumulates in plasma does vary between mammalian species, and this is believed

Wirosoetisno, Djoko

393

Inhibition in Verbal Working Memory Revealed by Brain Activation  

Microsoft Academic Search

There are many occasions in which humans and other animals must inhibit the production of some behavior or inhibit the processing of some internal representation. Success in inhibitory processing under normal circumstances can be revealed by the fact that certain brain pathologies render inhibitory processing ineffective. These pathologies often have been associated with damage to frontal cortex, including lateral and

John Jonides; Edward E. Smith; Christy Marshuetz; Robert A. Koeppe; Patricia A. Reuter-Lorenz

1998-01-01

394

Inhibition of Tooth Eruption in the Rat by a Bisphosphonate  

Microsoft Academic Search

Studies of osteopetrotic rodents suggest that localized alveolar bone resorption must occur if the tooth is to To test this hypothesis directly, we injected postnatal rats with pamidronate, a bisphosphonate that reduces bone resorption by osteoclasts, The results of these experiments demonstrate that this bisphosphonate inhibits the time of tooth of both rat molars and incisors. Pamidronate does not inhibit

R. L. Grier; G. E. Wise

1998-01-01

395

Action spectra for the inhibition of growth in radish hypocotyls  

Microsoft Academic Search

In etiolated seedlings of Raphanus sativus L. the inhibition of hypocotyl elongation by continuous light showed a major bimodal peak of action in the red and far-red, and two minor peaks in the blue regions of the spectrum. It is argued that, under conditions of prolonged irradiation, phytochrome is the pigment controlling the inhibition of hypocotyl elongation by red and

Ann M. Jose; Daphne Vince-Prue

1977-01-01

396

Sticky Plans: Inhibition and Binding during Serial-Task Control  

ERIC Educational Resources Information Center

Recent evidence suggests substantial response-time costs associated with lag-2 repetitions of tasks within explicitly controlled task sequences [Koch, I., Philipp, A. M., Gade, M. (2006). Chunking in task sequences modulates task inhibition. "Psychological Science," 17, 346-350; Schneider, D. W. (2007). Task-set inhibition in chunked task…

Mayr, Ulrich

2009-01-01

397

Simulating cholinesterase inhibition in birds caused by dietary insecticide exposure  

USGS Publications Warehouse

We describe a stochastic simulation model that simulates avian foraging in an agricultural landscape to evaluate factors affecting dietary insecticide exposure and to predict post-exposure cholinesterase (ChE) inhibition. To evaluate the model, we simulated published field studies and found that model predictions of insecticide decay and ChE inhibition reasonably approximated most observed results. Sensitivity analysis suggested that foraging location usually influenced ChE inhibition more than diet preferences or daily intake rate. Although organophosphorus insecticides usually caused greater inhibition than carbamate insecticides, insecticide toxicity appeared only moderately important. When we simulated impact of heavy insecticide applications during breeding seasons of 15 wild bird species, mean maximum ChE inhibition in most species exceeded 20% at some point. At this level of inhibition, birds may experience nausea and/or may exhibit minor behavioral changes. Simulated risk peaked in April-May and August-September and was lowest in July. ChE inhibition increased with proportion of vegetation in the diet. This model, and ones like it, may help predict insecticide exposure of and sublethal ChE inhibition in grassland animals, thereby reducing dependence of ecological risk assessments on field studies alone.

Corson, M.S.; Mora, M.A.; Grant, W.E.

1998-01-01

398

Recreational Use of Cocaine Eliminates Inhibition of Return  

Microsoft Academic Search

Chronic and recreational use of cocaine has been shown to impair inhibitory output control (response inhibition) but whether input control is also affected is an open question. For the first time, this study compared the ability to perform a cued target-discrimination task that measured inhibition of return (IOR), a reflexive inhibitory mechanism that delays attention from returning to a previously

Lorenza S. Colzato; Bernhard Hommel

2009-01-01

399

Adult attachment and attentional inhibition of interpersonal stimuli  

Microsoft Academic Search

In two studies, we used a negative affective priming task with pictures of angry (Study 1), sad (Study 2), and happy faces (Studies 1 and 2) to measure attentional inhibition of emotional stimuli as a function of attachment style. Results showed that attachment avoidance was associated with a stronger inhibition of both angry and sad faces. This indicates that the

Marieke Dewitte

2011-01-01

400

REGULAR ARTICLE Why calcium inhibits magnesium-dependent enzyme  

E-print Network

REGULAR ARTICLE Why calcium inhibits magnesium-dependent enzyme phosphoserine phosphatase. Keywords Phosphoserine phosphatase Á Magnesium Á Calcium Á Density functional calculations Á Inhibition mechanism 1 Introduction Phosphoserine phosphatase (PSP, EC 3.1.3.3) is a mono- nuclear magnesium

Liao, Rongzhen

401

Cholesterol Depletion Delocalizes Phosphatidylinositol Bisphosphate and Inhibits Hormone-stimulated  

E-print Network

Cholesterol Depletion Delocalizes Phosphatidylinositol Bisphosphate and Inhibits Hormone- enriched domains (DIGs) are cholesterol-enriched mem- brane domains that have been implicated in signal) are compartmentalized in these domains. We report here that depletion of cellular cholesterol leads to the inhibition

Pike, Linda J.

402

Fermentation of lignocellulosic hydrolysates. I: inhibition and detoxification  

Microsoft Academic Search

The ethanol yield and productivity obtained during fermentation of lignocellulosic hydrolysates is decreased due to the presence of inhibiting compounds, such as weak acids, furans and phenolic compounds formed or released during hydrolysis. This review describes the effect of various detoxification methods on the fermentability and chemical composition of the hydrolysates. Inhibition of fermentation can be relieved upon treatment with

Eva Palmqvist; Bärbel Hahn-Hägerdal

2000-01-01

403

Cyclooxygenase inhibition and baroreflex sensitivity in humans.  

PubMed

Animal studies suggest that prostanoids (i.e., such as prostacyclin) may sensitize or impair baroreceptor and/or baroreflex responsiveness depending on the site of administration and/or inhibition. We tested the hypothesis that acute inhibition of cyclooxygenase (COX), the rate-limiting enzyme in prostanoid synthesis, impairs baroreflex regulation of cardiac period (R-R interval) and muscle sympathetic nerve activity (MSNA) in humans and augments pressor reactivity. Baroreflex sensitivity (BRS) was determined at baseline (preinfusion) and 60 min after (postinfusion) intravenous infusion of a COX antagonist (ketorolac; 45 mg) (24 +/- 1 yr; n = 12) or saline (25 +/- 1 yr; n = 12). BRS was assessed by using the modified Oxford technique (bolus intravenous infusion of nitroprusside followed by phenylephrine). BRS was quantified as the slope of the linear portion of the 1) R-R interval-systolic blood pressure relation (cardiovagal BRS) and 2) MSNA-diastolic blood pressure relation (sympathetic BRS) during pharmacological changes in arterial blood pressure. Ketorolac did not alter cardiovagal (19.4 +/- 2.1 vs. 18.4 +/- 2.4 ms/mmHg preinfusion and postinfusion, respectively) or sympathetic BRS (-2.9 +/- 0.7 vs. -2.6 +/- 0.4 arbitrary units.beat(-1).mmHg(-1)) but significantly decreased a plasma biomarker of prostanoid generation (plasma thromboxane B2) by 53 +/- 11%. Cardiovagal BRS (21.3 +/- 3.8 vs. 21.2 +/- 3.0 ms/mmHg), sympathetic BRS (-3.4 +/- 0.3 vs. -3.2 +/- 0.2 arbitrary units.beat(-1).mmHg(-1)), and thromboxane B2 (change in -1 +/- 12%) were unchanged in the control (saline infusion) group. Pressor responses to steady-state incremental (0.5, 1.0, and 1.5 microg.kg(-1).min(-1)) infusion (5 min/dose) of phenylephrine were not altered by ketorolac (n = 8). Collectively, these data indicate that acute pharmacological antagonism of the COX enzyme does not impair BRS (cardiovagal or sympathetic) or augment pressor reactivity in healthy young adults. PMID:15486039

Monahan, Kevin D; Ray, Chester A

2005-02-01

404

SYNAPTIC INHIBITION IN AN ISOLATED NERVE CELL  

PubMed Central

Following the preceding studies on the mechanisms of excitation in stretch receptor cells of crayfish, this investigation analyzes inhibitory activity in the synapses formed by two neurons. The cell body of the receptor neuron is located in the periphery and sends dendrites into a fine muscle strand. The dendrites receive innervation through an accessory nerve fiber which has now been established to be inhibitory. There exists a direct peripheral inhibitory control mechanism which can modulate the activity of the stretch receptor. The receptor cell which can be studied in isolation was stimulated by stretch deformation of its dendrites or by antidromic excitation and the effect of inhibitory impulses on its activity was analyzed. Recording was done mainly with intracellular leads inserted into the cell body. 1. Stimulation of the relatively slowly conducting inhibitory nerve fiber either decreases the afferent discharge rate or stops impulses altogether in stretched receptor cells. The inhibitory action is confined to the dendrites and acts on the generator mechanism which is set up by stretch deformation. By restricting depolarization of the dendrites above a certain level, inhibition prevents the generator potential from attaining the "firing level" of the cell. 2. The same inhibitory impulse may set up a postsynaptic polarization or a depolarization, depending on the resting potential level of the cell. The membrane potential at which the inhibitory synaptic potential reverses its polarity, the equilibrium level, may vary in different preparations. The inhibitory potentials increase as the resting potential is displaced in any direction from the inhibitory equilibrium. 3. The inhibitory potentials usually rise to a peak in about 2 msec. and decay in about 30 msec. After repetitive inhibitory stimulation a delayed secondary polarization phase has frequently been seen, prolonging the inhibitory action. Repetitive inhibitory excitation may also be followed by a period of facilitation. Some examples of "direct" excitation by the depolarizing action of inhibitory impulses are described. 4. The interaction between antidromic and inhibitory impulses was studied. The results support previous conclusions (a) that during stretch the dendrites provide a persisting "drive" for the more central portions of the receptor cell, and (b) that antidromic all-or-none impulses do not penetrate into the distal portions of stretch-depolarized dendrites. The "after-potentials" of antidromic impulses are modified by inhibition. 5. Evidence is presented that inhibitory synaptic activity increases the conductance of the dendrites. This effect may occur in the absence of inhibitory potential changes. PMID:13252239

Kuffler, Stephen W.; Eyzaguirre, Carlos

1955-01-01

405

Pancreatic polypepetide inhibits pancreatic enzyme secretion via a cholinergic pathway  

SciTech Connect

In rat pancreatic slices, rat pancreatic polypeptide (PP) or C-terminal hexapeptide of PP (PP-(31-36)) inhibited potassium-stimulated amylase release in a dose-dependent manner. The inhibition was unaffected by addition of hexamethonium but blocked by atropine. In contrast, PP-(31-36) did not have any effect on acetylcholine- or cholecystokinin octapeptide-stimulated amylase release. In addition, when pancreatic slices were incubated with ({sup 3}H)choline, PP-(31-36) inhibited the potassium-evoked release of synthesized ({sup 3}H)acetylcholine in a dose-dependent manner. The inhibitory action of PP was unaffected by adrenergic, dopaminergic, or opioid receptor antagonists. Thus PP inhibits pancreatic enzyme secretion via presynaptic modulation of acetylcholine release. This newly identified pathway provides a novel mechanism for hormonal inhibition of pancreatic enzyme secretion via modulation of the classic neurotransmitter function.

Jung, G.; Louie, D.S.; Owyang, C. (Univ. of Michigan Medical Center, Ann Arbor (USA))

1987-11-01

406

Emergence of embryonic pattern through contact inhibition of locomotion.  

PubMed

The pioneering cell biologist Michael Abercrombie first described the process of contact inhibition of locomotion more than 50 years ago when migrating fibroblasts were observed to rapidly change direction and migrate away upon collision. Since then, we have gleaned little understanding of how contact inhibition is regulated and only lately observed its occurrence in vivo. We recently revealed that Drosophila macrophages (haemocytes) require contact inhibition for their uniform embryonic dispersal. Here, to investigate the role that contact inhibition plays in the patterning of haemocyte movements, we have mathematically analysed and simulated their contact repulsion dynamics. Our data reveal that the final pattern of haemocyte distribution, and the details and timing of its formation, can be explained by contact inhibition dynamics within the geometry of the Drosophila embryo. This has implications for morphogenesis in general as it suggests that patterns can emerge, irrespective of external cues, when cells interact through simple rules of contact repulsion. PMID:23172914

Davis, John R; Huang, Chieh-Yin; Zanet, Jennifer; Harrison, Sam; Rosten, Edward; Cox, Susan; Soong, Daniel Y; Dunn, Graham A; Stramer, Brian M

2012-12-01

407

Inhibition of Return in the Visual Field  

PubMed Central

Inhibition of return (IOR) as an indicator of attentional control is characterized by an eccentricity effect, that is, the more peripheral visual field shows a stronger IOR magnitude relative to the perifoveal visual field. However, it could be argued that this eccentricity effect may not be an attention effect, but due to cortical magnification. To test this possibility, we examined this eccentricity effect in two conditions: the same-size condition in which identical stimuli were used at different eccentricities, and the size-scaling condition in which stimuli were scaled according to the cortical magnification factor (M-scaling), thus stimuli being larger at the more peripheral locations. The results showed that the magnitude of IOR was significantly stronger in the peripheral relative to the perifoveal visual field, and this eccentricity effect was independent of the manipulation of stimulus size (same-size or size-scaling). These results suggest a robust eccentricity effect of IOR which cannot be eliminated by M-scaling. Underlying neural mechanisms of the eccentricity effect of IOR are discussed with respect to both cortical and subcortical structures mediating attentional control in the perifoveal and peripheral visual field. PMID:23820946

Bao, Yan; Lei, Quan; Fang, Yuan; Tong, Yu; Schill, Kerstin; Pöppel, Ernst; Strasburger, Hans

2013-01-01

408

Clofilium inhibits Slick and Slack potassium channels  

PubMed Central

Slick and Slack high-conductance potassium channels have been recently discovered, and are found in the central nervous system and in the heart. Both channels are activated by Na+ and Cl?, and Slick channels are also inhibited by adenosine triphospate (ATP). An important role of setting the resting membrane potential and controlling the basal excitability of neurons has been suggested for these channels. In addition, no specific blockers for these channels are known up to the present. With the purpose of studying the pharmacological characteristics of Slick and Slack channels, the effects of exposure to the antiarrhythmic compound clofilium were evaluated. Clofilium was able to modulate the activity of Slick and Slack channels effectively, with a stronger effect on Slack than Slick channels. In order to evaluate the pharmacological behavior of Slick and Slack channels further, 38 commonly used potassium channel blockers were tested. Screening of these compounds did not reveal any modulators of Slick and Slack channels, except for clofilium. The present study provides a first approach towards elucidating the pharmacological characteristics of Slick and Slack channels and could be the basis for future studies aimed at developing potent and specific blockers and activators for these channels. PMID:23271893

de los Angeles Tejada, Maria; Stolpe, Kathleen; Meinild, Anne-Kristine; Klaerke, Dan A

2012-01-01

409

Blocking the T4 lysis inhibition phenotype.  

PubMed

Nonlysogenic Escherichia coli K cells exhibit a delay in lysis when infected by T4rII phage termed lysis inhibition (LIN). E. coli K cells expressing lambda rexB from either a prophage defective for rexA, or a multicopy plasmid supported T4rII infection, but prevented the establishment of LIN. In addition, E. coli null mutations in either the periplasmic "tail-specific protease" tsp, or the 10Sa RNA ssrA, completely blocked the establishment of LIN following T4 infections. The expression of rexB in the absence of rexA resulted in several cellular phenotypes, including aberrant cell surface morphology, the partial to near complete suppression of mutations of lambda S and T4t holin genes, and lysis by cells aging on plates or growing with high rexB expression at elevated temperatures. These activities of RexB were impeded in the presence of RexA. PMID:14637004

Slavcev, Roderick A; Hayes, Sidney

2003-12-01

410

PCB126 inhibits adipogenesis of human preadipocytes.  

PubMed

Emerging evidence indicates that persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), are involved in the development of diabetes. Dysfunctional adipocytes play a significant role in initiating insulin resistance. Preadipocytes make up a large portion of adipose tissue and are necessary for the generation of functional mature adipocytes through adipogenesis. PCB126 is a dioxin-like PCB and a potent aryl hydrocarbon receptor (AhR) agonist. We hypothesized that PCB126 may be involved in the development of diabetes through disruption of adipogenesis. Using a newly developed human preadipocyte cell line called NPAD (Normal PreADipocytes), we found that exposure of preadipocytes to PCB126 resulted in significant reduction in their subsequent ability to fully differentiate into adipocytes, more so than when the cells were exposed to PCB126 during differentiation. Reduction in differentiation by PCB126 was associated with downregulation of transcript levels of a key adipocyte transcription factor, PPAR?, and late adipocyte differentiation genes. An AhR antagonist, CH223191, blocked this effect. These studies indicate that preadipocytes are particularly sensitive to the effects of PCB126 and suggest that AhR activation inhibits PPAR? transcription and subsequent adipogenesis. Our results validate the NPAD cell line as a useful model for studying the effects of POPs on adipogenesis. PMID:25304490

Gadupudi, Gopi; Gourronc, Francoise A; Ludewig, Gabriele; Robertson, Larry W; Klingelhutz, Aloysius J

2015-02-01

411

Proline inhibits aggregation during protein refolding.  

PubMed Central

The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate(s) and trapping the folding intermediate(s) into enzymatically inactive, "aggregation-insensitive" state(s). However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations (>1.5 M), proline is shown to form loose, higher-order molecular aggregate(s). The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone. PMID:10716186

Samuel, D.; Kumar, T. K.; Ganesh, G.; Jayaraman, G.; Yang, P. W.; Chang, M. M.; Trivedi, V. D.; Wang, S. L.; Hwang, K. C.; Chang, D. K.; Yu, C.

2000-01-01

412

Stac3 inhibits myoblast differentiation into myotubes.  

PubMed

The functionally undefined Stac3 gene, predicted to encode a SH3 domain- and C1 domain-containing protein, was recently found to be specifically expressed in skeletal muscle and essential to normal skeletal muscle development and contraction. In this study we determined the potential role of Stac3 in myoblast proliferation and differentiation, two important steps of muscle development. Neither siRNA-mediated Stac3 knockdown nor plasmid-mediated Stac3 overexpression affected the proliferation of C2C12 myoblasts. Stac3 knockdown promoted the differentiation of C2C12 myoblasts into myotubes as evidenced by increased fusion index, increased number of nuclei per myotube, and increased mRNA and protein expression of myogenic markers including myogenin and myosin heavy chain. In contrast, Stac3 overexpression inhibited the differentiation of C2C12 myoblasts into myotubes as evidenced by decreased fusion index, decreased number of nuclei per myotube, and decreased mRNA and protein expression of myogenic markers. Compared to wild-type myoblasts, myoblasts from Stac3 knockout mouse embryos showed accelerated differentiation into myotubes in culture as evidenced by increased fusion index, increased number of nuclei per myotube, and increased mRNA expression of myogenic markers. Collectively, these data suggest an inhibitory role of endogenous Stac3 in myoblast differentiation. Myogenesis is a tightly controlled program; myofibers formed from prematurely differentiated myoblasts are dysfunctional. Thus, Stac3 may play a role in preventing precocious myoblast differentiation during skeletal muscle development. PMID:24788338

Ge, Xiaomei; Zhang, Yafei; Park, Sungwon; Cong, Xiaofei; Gerrard, David E; Jiang, Honglin

2014-01-01

413

Inhibition of imitative behaviour and social cognition  

PubMed Central

There is converging evidence that the observation of an action activates a corresponding motor representation in the observer through a ‘mirror-matching’ mechanism. However, research on such ‘shared representations’ of perception and action has widely neglected the question of how we can distinguish our own motor intentions from externally triggered motor representations. By investigating the inhibition of imitative response tendencies, as an index for the control of shared representations, we can show that self–other distinction plays a fundamental role in the control of shared representations. Furthermore, we demonstrate that overlapping brain activations can be found in the anterior fronto-median cortex (aFMC) and the temporo-parietal junction (TPJ) area for the control of shared representations and complex social-cognitive tasks, such as mental state attribution. In a functional magnetic resonance imaging experiment, we functionally dissociate the roles of TPJ and aFMC during the control of shared representations. Finally, we propose a hypothesis stating that the control of shared representations might be the missing link between functions of the mirror system and mental state attribution. PMID:19620107

Brass, Marcel; Ruby, Perrine; Spengler, Stephanie

2009-01-01

414

A calcium-inhibited Drosophila adenylyl cyclase.  

PubMed

Mammals possess a family of transmembrane, G-protein-responsive adenylyl cyclase isoforms (tmACs) encoded by distinct genes differing in their patterns of expression and modes of biochemical regulation. Our previous work confirmed that Drosophila melanogaster also possesses a family of tmAC isoforms defining the fly as a suitable genetic model for discerning mammalian tmAC function. We now describe a Drosophila tmAC, DAC39E, which employs a novel means for regulating its expression; differential exon utilization results in a developmental switch in DAC39E protein. DAC39E protein sequence is most closely related to mammalian type III AC, and it is predominantly expressed in the central nervous system (CNS) and olfactory organs, suggesting a role in processing sensory signaling inputs. DAC39E catalytic activity is inhibited by micromolar concentrations of calcium; therefore, DAC39E is oppositely regulated by calcium compared to the only other tmAC shown to be expressed in the Drosophila CNS, Rutabaga AC. The presence of both positively and negatively regulated tmACs suggests a complex mode of cross-talk between cAMP and calcium signal transduction pathways in the fly CNS. PMID:10656970

Iourgenko, V; Levin, L R

2000-02-01

415

Orbitofrontal cortex mediates inhibition of return.  

PubMed

Recent accounts have proposed that orbitofrontal cerebral cortex mediates the control of behavior based on emotional feedback and its somatic correlates. Here, we describe the performance of a patient with circumscribed damage to orbitofrontal cortex during a task that requires switching between sensory-motor mappings, contingent on the occurrence of positive and negative reward feedbacks. In this test, normal subjects and other patients with prefrontal damage show an increase in latencies for eye movements towards locations at which a negative feedback was presented on the preceding trial. In contrast, our patient does not show this reward-dependent inhibition of return effect on saccades. She was also found to make an increased rate of ocular refixations during visual search and used a disorganized search strategy in a token foraging task. These findings suggest that orbital regions of the prefrontal cortex mediate an inhibitory effect on actions directed towards locations that have been subject to negative reinforcement. Further, this mechanism seems to play a role in controlling natural search and foraging behavior. PMID:12207988

Hodgson, T L; Mort, D; Chamberlain, M M; Hutton, S B; O'Neill, K S; Kennard, C

2002-01-01

416

Inhibition of glioblastoma malignancy by Lgl1  

PubMed Central

lethal giant larvae (lgl) was first identified as a tumor suppressor in Drosophila, where its loss repressed the differentiation and promoted the invasion of neuroblasts, the Drosophila equivalent of the neural stem cell. Recently we have shown that a human homolog of Lgl, Lgl1 (LLGL1), is constitutively phosphorylated and inactivated in glioblastoma cells; this occurs as a downstream consequence of PTEN loss, one of the most frequent genetic events in glioblastoma. Here we have investigated the consequences of this loss of functional Lgl1 in glioblastoma in vivo. We used a doxycycline-inducible system to express a non-phosphorylatable, constitutively active version of Lgl1 (Lgl3SA) in either a glioblastoma cell line or primary glioblastoma cells isolated under neural stem cell culture conditions from patients. In both types of cells, expression of Lgl3SA, but not wild type Lgl1, inhibited cell motility in vitro. Induction of Lgl3SA in intracerebral xenografts markedly reduced the in vivo invasion of primary glioblastoma cells. Lgl3SA expression also induced the differentiation of glioblastoma cells in vitro and in vivo along the neuronal lineage. Thus the central features of Lgl function as a tumor suppressor in Drosophila are conserved in human glioblastoma. PMID:25426552

Gont, Alexander; Hanson, Jennifer E.L.; Lavictoire, Sylvie J.; Daneshmand, Manijeh; Nicholas, Garth; Woulfe, John; Kassam, Amin; Da Silva, Vasco F.; Lorimer, Ian A.J.

2014-01-01

417

Inhibition of angiogenesis by S-adenosylmethionine  

SciTech Connect

Highlights: {yields} Effects of S-adenosylmethionine (SAM) were investigated in endothelial cells. {yields} Our results showed that SAM decreased proliferation of endothelial cells. {yields} SAM influentially inhibited the percentage of cell migration. {yields} SAM probably stopped migration as independent from its effects on proliferation. {yields} SAM was shown to suppress in vitro angiogenesis. -- Abstract: Metastasis is a leading cause of mortality and morbidity in cancer. One of the steps in metastasis process is the formation of new blood vessels. Aberrant DNA methylation patterns are common in cancer cells. In recent studies, S-adenosylmethionine (SAM), which is a DNA methylating agent, has been found to have inhibitory effects on some carcinoma cells in vivo and in vitro. In the present study, we have used SAM to investigate whether it is effective against angiogenesis in vitro. Our results have shown that SAM can reduce the formation and organization of capillary-like structures of endothelial cells in tumoral environment. Besides, we have found SAM can block endothelial cell proliferation and the migration of cells towards growth factors-rich media. In conclusion, our study suggests that SAM may be used against angiogenesis as a natural bio-product.

Sahin, Mehmet, E-mail: msahin@akdeniz.edu.tr [Health Sciences Research Centre, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)] [Health Sciences Research Centre, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey); Sahin, Emel [Department of Central Laboratory, Clinical Biochemistry Unit, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)] [Department of Central Laboratory, Clinical Biochemistry Unit, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey); Guemueslue, Saadet [Department of Biochemistry, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)] [Department of Biochemistry, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey); Erdogan, Abdullah [Department of Thoracic Surgery, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)] [Department of Thoracic Surgery, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey); Gueltekin, Meral [Health Sciences Research Centre, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)] [Health Sciences Research Centre, Faculty of Medicine, Akdeniz University, 07070 Antalya (Turkey)

2011-04-29

418

Proline inhibits aggregation during protein refolding.  

PubMed

The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate(s) and trapping the folding intermediate(s) into enzymatically inactive, "aggregation-insensitive" state(s). However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations (>1.5 M), proline is shown to form loose, higher-order molecular aggregate(s). The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone. PMID:10716186

Samuel, D; Kumar, T K; Ganesh, G; Jayaraman, G; Yang, P W; Chang, M M; Trivedi, V D; Wang, S L; Hwang, K C; Chang, D K; Yu, C

2000-02-01

419

Methylsulfonylmethane inhibits NLRP3 inflammasome activation.  

PubMed

Methylsulfonylmethane (MSM) is an organosulfur compound and the health benefits associated with MSM include inflammation. Although MSM has been shown to have various physiological effects, no study has yet focused on inflammasome activation. The inflammasome is a multiprotein complex that serves as a platform for caspase 1-dependent proteolytic maturation and secretion of interleukin-1? (IL-1?). In this study, we tested the effect of MSM on inflammasome activation using mouse and human macrophages. In our results, MSM significantly attenuated NLRP3 inflammasome activation in lipopolysaccharide-primed macrophages, although it had no effect on NLCR4 or AIM2 inflammasome activation. Extracts of MSM-enriched vegetables presented the same inhibitory effect on NLRP3 inflammasome activation as MSM. MSM also attenuated the transcriptional expression of IL-1?, IL-1?, IL-6, and NLRP3. Taken together, these results show that MSM has anti-inflammatory characteristics, interrupts NLRP3 inflammasome activation, and inhibits pro-cytokine expression. We further confirmed the intracellular mechanism of MSM in relation to NLRP3 inflammasome activation, followed by comparison with that of DMSO. Both chemicals showed a synergic effect on anti-NLRP3 activation and attenuated production of mitochondrial reactive oxygen species (ROS). Thus, MSM is a selective inhibitor of NLRP3 inflammasome activation and can be developed as a supplement to control several metabolic disorders. PMID:25461402

Ahn, Huijeong; Kim, Jeeyoung; Lee, Min-Jae; Kim, Young Jin; Cho, Young-Wook; Lee, Geun-Shik

2015-02-01

420

Treatment with pyrophosphate inhibits uremic vascular calcification.  

PubMed

Pyrophosphate, which may be deficient in advanced renal failure, is a potent inhibitor of vascular calcification. To explore its use as a potential therapeutic, we injected exogenous pyrophosphate subcutaneously or intraperitoneally in normal rats and found that their plasma pyrophosphate concentrations peaked within 15 min. There was a single exponential decay with a half-life of 33 min. The kinetics were indistinguishable between the two routes of administration or in anephric rats. The effect of daily intraperitoneal pyrophosphate injections on uremic vascular calcification was then tested in rats fed a high-phosphate diet containing adenine for 28 days to induce uremia. Although the incidence of aortic calcification varied and was not altered by pyrophosphate, the calcium content of calcified aortas was significantly reduced by 70%. Studies were repeated in uremic rats given calcitriol to produce more consistent aortic calcification and treated with sodium pyrophosphate delivered intraperitoneally in a larger volume of glucose-containing solution to prolong plasma pyrophosphate levels. This maneuver significantly reduced both the incidence and amount of calcification. Quantitative histomorphometry of bone samples after double-labeling with calcein indicated that there was no effect of pyrophosphate on the rates of bone formation or mineralization. Thus, exogenous pyrophosphate can inhibit uremic vascular calcification without producing adverse effects on bone. PMID:21124302

O'Neill, W Charles; Lomashvili, Koba A; Malluche, Hartmut H; Faugere, Marie-