Search results for " phosphatase"
showing 10 items of 329 documents
Use of sonication for measuring acid phosphatase activity in soil
2000
Extracellular enzymes in soil often occur in immobilised forms, a state that may alter their interactions with substrates in comparison with enzymes in the solution phase. Sonication was evaluated for its usefulness in studying immobilised acid phosphatase by dispersing soil aggregates. Factors affecting soil dispersion during ultrasound application were soil extraction ratio, total applied energy and power output ml−1 of sonicated soil slurry. For the clay loam soil used, optimal values for these variables were, respectively, 1:6 (w/v) and, at least, 1800 J ml−1 and 15 W ml−1. At the optimal sonication conditions for soil dispersion a substantial increase in phosphatase activity (up to 156…
Effects of a phycotoxin, okadaic acid, on oyster heart cell survival
2008
Okadaic acid (OA) is a dinoflagellate toxin which accumulates in shellfish producing diarrhetic shellfish poisoning (DSP) in humans. It was found that OA is a highly selective inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A) which produces a marked increase in phosphorylation of several proteins, including p38 mitogen-activated protein (MAP) kinase. The cytotoxicity attributed to OA and the effects on p38 MAP kinase and calcium current were examined in the oyster Crassostrea gigas in this study. Data showed that p38 MAP kinase is strongly expressed in oyster heart and that OA bioaccumulated in cultured heart cells. Hence the effects of OA was tested in vitro and in vivo on oyste…
Isopropanolic Cimicifuga racemosa is favorable on bone markers but neutral on an osteoblastic cell line
2009
Postmenopausal women treated with an isopropanolic extract of Cimicifuga racemosa underwent a decrease in the urinary concentration of N-telopeptides, a marker of bone resorption, and an increase in alkaline phosphatase, a marker of bone formation, at the third month of therapy. Serum from treated women did not modify the activity of alkaline phosphatase or the expression of three genes, runt-related transcription factor-2 (Runx-2), alkaline phosphatase, and osteocalcin, when added to the MC3T3-E1 osteoblastic cell line.
Effects of a low-frequency sound wave therapy programme on functional capacity, blood circulation and bone metabolism in frail old men and women
2009
Objective: To evaluate the effects of a low-frequency sound wave therapy programme on functional capacity, blood circulation and bone metabolism of the frail elderly. Design: Single-blind, randomized, controlled trial. Setting: Two senior service centres. Subjects: Forty-nine volunteers (14 males and 35 females) aged 62—93 years with up to 12 diagnosed diseases were allocated in either the intervention group (n = 30) or control group (n = 19). Intervention: The intervention group underwent sound wave therapy, 3—5 times a week for 30 minutes per session over a period of 6 months. The control group received no intervention. Main measurements: Blood pressure, functional capacity, mobility, bo…
Impact of Pulsed Electric Fields on Enzymes
2017
International audience; Pulsed electric field (PEF) processing has emerged as a promising technology in the development of tailor-made processes to effectively control the enzyme activity. It has been proven as an effective technique for the preservation of food products as it can result in substantial inactivation of most undesirable enzymes. When compared to microbial inactivation, however, large specific energy inputs are required to inactivate enzymes. The existing evidence suggests that PEF can also stimulate the activity of beneficial enzymes at low intense treatments. The PEF affects enzyme activity by changing mainly the secondary (α-helix, β-sheets, etc.), tertiary (spatial conform…
Roflumilast N-oxide reverses corticosteroid resistance in neutrophils from patients with chronic obstructive pulmonary disease
2013
Background Glucocorticoid functions are markedly impaired in patients with chronic obstructive pulmonary disease (COPD). The phosphodiesterase 4 inhibitor roflumilast N-oxide (RNO) is the active metabolite of roflumilast approved as a treatment to reduce the risk of exacerbations in patients with severe COPD. Objective We sought to characterize the differential effects of RNO versus corticosteroids and their potential additive/synergistic effect in neutrophils from patients with COPD, thus providing scientific rationale for the combination of roflumilast with corticosteroids in the clinic. Methods Peripheral blood neutrophils were isolated from patients with COPD (n = 32), smokers (n = 7), …
Interaction of Mitogen-activated Protein Kinases with the Kinase Interaction Motif of the Tyrosine Phosphatase PTP-SL Provides Substrate Specificity …
1999
ERK1 and ERK2 associate with the tyrosine phosphatase PTP-SL through a kinase interaction motif (KIM) located in the juxtamembrane region of PTP-SL. A glutathione S-transferase (GST)-PTP-SL fusion protein containing the KIM associated with ERK1 and ERK2 as well as with p38/HOG, but not with the related JNK1 kinase or with protein kinase A or C. Accordingly, ERK2 showed in vitro substrate specificity to phosphorylate GST-PTP-SL in comparison with GST-c-Jun. Furthermore, tyrosine dephosphorylation of ERK2 by the PTP-SLDeltaKIM mutant was impaired. The in vitro association of ERK1/2 with GST-PTP-SL was highly stable; however, low concentrations of nucleotides partially dissociated the ERK1/2.P…
A novel regulatory mechanism of MAP kinases activation and nuclear translocation mediated by PKA and the PTP-SL tyrosine phosphatase
1999
Protein tyrosine phosphatase PTP-SL retains mitogen-activated protein (MAP) kinases in the cytoplasm in an inactive form by association through a kinase interaction motif (KIM) and tyrosine dephosphorylation. The related tyrosine phosphatases PTP-SL and STEP were phosphorylated by the cAMP-dependent protein kinase A (PKA). The PKA phosphorylation site on PTP-SL was identified as the Ser231 residue, located within the KIM. Upon phosphorylation of Ser231, PTP-SL binding and tyrosine dephosphorylation of the MAP kinases extracellular signal–regulated kinase (ERK)1/2 and p38α were impaired. Furthermore, treatment of COS-7 cells with PKA activators, or overexpression of the Cα catalytic subunit …
The bacterial cytolethal distending toxin (CDT) triggers a G2 cell cycle checkpoint in mammalian cells without preliminary induction of DNA strand br…
1999
The bacterial cytolethal distending toxin (CDT) was previously shown to arrest the tumor-derived HeLa cell line in the G2-phase of the cell cycle through inactivation of CDK1, a cyclin-dependent kinase whose state of activation determines entry into mitosis. We have analysed the effects induced in HeLa cells by CDT, in comparison to those induced by etoposide, a prototype anti-tumoral agent that triggers a G2 cell cycle checkpoint by inducing DNA damage. Both CDT and etoposide inhibit cell proliferation and induces the formation of enlarged mononucleated cells blocked in G2. In both cases, CDK1 from arrested cells could be re-activated both in vitro by dephosphorylation by recombinant Cdc25…
Tropicibacter multivorans sp. nov., an aerobic alphaproteobacterium isolated from surface seawater.
2011
Strain MD5T, an aerobic marine alphaproteobacterium, was isolated from Mediterranean seawater at Malvarrosa beach, Valencia, Spain. The strain was characterized in a polyphasic study and was placed phylogenetically within the Roseobacter clade in the family Rhodobacteraceae . Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MD5T is related to Tropicibacter naphthalenivorans C02T, Phaeobacter inhibens T5T, P. gallaeciensis BS107T and P. daeponensis TF-218T, with 96.9, 96.2, 96.1 and 96.1 % sequence similarity, respectively. Phylogenetic analyses also showed that strain MD5T forms a stable clade only with T. naphthalenivorans C02T. Strain MD5T requires Na+ plus a diva…