Concentration-dependent Increase In Activity Research Articles

Galanthus elwesii Hook.f.’nin Farklı Ekstraktlarının Serbest Radikal Yakalama ve Metal Şelatlama Aktivitelerinin Tespit Edilmesi

Natural compounds play an important role among antioxidants that protect the human body against oxidative stress. Many plants may have high levels of antioxidant capacity through the compounds they contain. In line with this information, in the current study, we aimed to evaluate the antioxidant properties of Galanthus elwesii Hook.f. In this context, we tested the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and metal chelating activities of different concentrations (12.5-400 mg/L) of methanol and water extracts obtained from the bulb part of this plant. A concentration-dependent increase in activity was observed for both extracts. DPPH scavenging (87.10%) and metal chelating (72.99%) activities demonstrated by 400 mg/L concentration applications came to the fore. In addition, it was determined that these data were significantly (p < 0.05) higher than the activity rates revealed by other applications. Considering the IC50 values, low values for DPPH scavenging and metal chelating activities (110.88 mg/L and 132.40 mg/L, respectively) were detected in water extracts. As a result, the importance of G. elwesii among plants that have the potential to be a rich source of antioxidants was revealed in this study.

Simvastatin, at clinically relevant concentrations, affects human uterine leiomyoma growth and extracellular matrix production

To observe the antifibroid effects of therapeutic concentrations of simvastatin, which interferes with cholesterol biosynthesis, a known precursor of five major classes of steroid hormones, including progesterone and estrogen, which play a major role in the development and growth of uterine leiomyomas. Two-dimensional and three-dimensional cell culture study of immortalized human leiomyoma and patient-matched myometrium cells treated with simvastatin. University laboratory. None. None. Cell proliferation, alteration in apoptotic signaling pathways, and extracellular matrix (ECM) protein production. Simvastatin demonstrated a concentration-dependent antiproliferative effect on both the leiomyoma cells and the patient-matched myometrium cells, but a higher inhibitory effect at lower concentrations of simvastatin was observed in leiomyoma cells. Simvastatin also regulated leiomyoma cell apoptosis through a concentration-dependent increase in activity of caspase-3. Simvastatin significantly inhibited expression of major ECM proteins collagen I, collagen III, fibronectin, versican, and brevican in leiomyoma cells at concentrations as low as 10-9mol/L within 48hours of exposure. Simvastatin induces apoptosis in uterine leiomyoma cells at low concentrations, as evidenced by increased active caspase levels. Furthermore, inhibited production of the ECM proteins may lead to reduction in tumor size. Simvastatin may represent a novel therapeutic treatment strategy for uterine leiomyomas.

Chromate tolerance and accumulation in Chlorella vulgaris L.: Role of antioxidant enzymes and biochemical changes in detoxification of metals

A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione, superoxide dismutase) and carotenoid, MDA level have been observed in the green alga Chlorella vulgaris following chromium exposure at different concentrations (0.01–100μgml−1). Simultaneously, decrease in growth rate, chlorophyll and protein contents was observed. In case of ascorbate peroxidase, glutathione peroxidase and superoxide dismutase a bell shaped dose response was evident, however, lipid peroxidation followed a linear relationship along with catalase activity, which could be used as biomarker of Cr toxicity and played important role in providing tolerance and subsequently, high accumulation potential of chromium in C. vulgaris. In present investigation, the green alga C. vulgaris respond better under chromium stress in terms of tolerance, growth and metal accumulating potential at higher concentration of Cr (VI) which could be employed in decontamination of chromium for environmental cleanup.

An enhancing effect of exogenous brassinolide on the growth and antioxidant activity in Chlorella vulgaris cultures under heavy metals stress

A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione reductase, ssuperoxide dismutase) and the level of total ascorbate and reduced glutathione have been observed in the green alga Chlorella vulgaris following heavy metals exposure. It was arranged in the following order: copper > lead > cadmium. It was also found that brassinolide activated enzymatic and non-enzymatic system in C. vulgaris cultures treated with heavy metals. Brassinolide plays an important role in plant responding to heavy metals’ stress. It has an anti-stress effect on C. vulgaris contaminated by heavy metals.

BCL2 Induces Suppressor of Cytokine Signaling-3 (SOCS3) Expression in Murine B Cells Via Pathways Involving an HSP70/90 Complex and Activation of p44/42 Map Kinase.

Polyclonal CD19+ B cells isolated from Bcl2-overexpressing Eμ-Bcl2 transgenic mice (Eμ-Bcl2tg+) overexpress SOCS3 protein. We previously reported that enforced expression of Bcl2 in BaF3 pro-B cells induces SOCS3 protein via p44/42 MAP Kinase activation. We also found that SOCS3 protein overexpression is an independent poor prognostic factor in patients with Bcl2-positive follicular lymphomas. We hypothesized that Bcl2 mediates induction of SOCS3 indirectly via cellular intermediaries that may alter cell signaling and/or apoptotic pathways in B cells. In the current study, magnetic bead B cell negative selection was used to isolate polyclonal CD19+ B cells from 24 week old Eμ-Bcl2tg+ mice (n=6). Bcl2-interacting proteins were then isolated from Eμ-Bcl2tg+ B cells by immunoprecipitation using a polyclonal anti-Bcl2 antibody. Bcl2 protein complexes separated by SDS-PAGE revealed several bands, with the most prominent bands noted at 70kDa and 90kDa, respectively. These bands were analyzed by mass spectrometry (LC MS/MS) and protein database analysis identified them as Heat Shock Proteins (HSP) 70 and 90β. LC MS/MS results were verified by co-immunoprecipitation of both HSP70 and HSP90β with Bcl2 in Eμ-Bcl2tg+ B cells. Co-immunoprecipitation assays with SOCS3 and Bax revealed no interaction with this protein complex. 5 × 106 Eμ-Bcl2tg+ B cells from individual mice were then cultured in microtiter plates using Supplented Iscove's Modified Dulbecco's Medium (SIMDM) with 10% FBS and were treated over 12 hours with escalating doses of the HSP90 inhibitor 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG). Immunoprecipitation with Bcl2 revealed that 17-AAG blocked the interaction between Bcl2 and HSP90β in a dose-dependent manner. Furthermore, Western analysis of Eμ-Bcl2tg+ B cells treated with 17-AAG revealed a marked decrease in SOCS3 protein expression compared with untreated cells. In addition, Eμ-Bcl2tg+ B cells exposed to increasing concentrations of 17-AAG showed a concentration-dependent increase in activity of caspase 3 and increased cell death compared with untreated cells. Next, to determine whether Bcl2-mediated SOCS3 overexpression in B cells involves STAT3-dependent or -independent mechanisms, we measured phospho-STAT3 levels relative to STAT3 in Eμ-Bcl2tg+ B cells cultured in the presence of escalating doses of IL-6. When probed with phospho-STAT3 and STAT3 antisera, Eμ-Bcl2tg+ B cells did not reveal STAT3 protein phosphorylation but revealed equivalent STAT3 protein levels in response to IL-6. Eμ-Bcl2tg+ B cells were then cultured as above in the presence or absence of a specific p44/42MAPK pathway inhibitor (MEK 1/2 inhibitor U0126), and whole cell lysates were analyzed for SOCS3 expression by Western analysis. When probed with SOCS3 antisera, B cells selectively grown in the presence of U0126 revealed complete abrogation of SOCS3 protein expression while those grown in the absence of inhibitor continued to harbor SOCS3 protein. Bcl2 protein levels remained unchanged in the presence or absence of U0126. Inhibitors of p38MAPK (SB203580), AKT (Triciribine), and PI3K (LY294002) did not affect SOCS3 expression. These results indicate that Bcl2-associated SOCS3 induction in murine B cells is dependent upon a HSP70/90 complex and involves activation of p44/42 MAPK. These studies illustrate a novel signaling pathway in B cells important for the regulation of caspase-mediated apoptosis.

α-Melanocyte-stimulating Hormone Reduces Impact of Proinflammatory Cytokine and Peroxide-generated Oxidative Stress on Keratinocyte and Melanoma Cell Lines

We have previously shown that alpha-melanocyte-stimulating hormone (alpha-MSH) can oppose tumor necrosis factor alpha activation of NF-kappaB (1-2 h) and intercellular adhesion molecule 1 up-regulation (mRNA by 3 h and protein by 24 h) in melanocytes and melanoma cells. The present study reports on the ability of four MSH peptides to control intracellular peroxide levels and glutathione peroxidase (GPx) activity in pigmentary and nonpigmentary cells. In human HBL melanoma and HaCaT keratinocytes tumor necrosis factor alpha and H(2)O(2) both activated GPx in a time- and concentration-dependent manner (by 30-45 min). alpha-MSH peptides were found to inhibit the stimulated GPx activity and had biphasic dose-response curves. MSH 1-13 and MSH [Nle(4)-d-Phe(7)] achieved maximum inhibition at 10(-10) and 10(-12) m, respectively. Higher concentrations (10-100 fold) of MSH 4-10 and MSH 11-13 were required to produce equivalent levels of inhibition. alpha-MSH was also capable of reducing peroxide accumulation within 15 min, and again this inhibition was biphasic. The data support a role of alpha-MSH in acute protection of cells to oxidative/cytokine action that precedes NF-kappaB and GPx activation. The rapidity and potency of the response to alpha-MSH in pigmentary and nonpigmentary cells suggest this to be a central role of this peptide in cutaneous cells.

Effect of fluoxetine on contractile activity of pregnant rat uterine rings

Objective: We sought to compare the effects of fluoxetine, imipramine, and nortriptyline on spontaneous and serotonin-activated contractile activity of the uterine rings from midterm and term pregnant rats. Study Design: Uterine rings from timed-pregnant Sprague-Dawley rats on day 14 (midgestation) and day 22 (term gestation) were used for isometric tension recording. Responses to cumulative concentrations of fluoxetine, imipramine, nortriptyline, and serotonin in the absence and presence of the monoamine reuptake inhibitors were studied. Results: Neither of the monoamine reuptake inhibitors significantly influenced spontaneous contractile activity, whereas the concentration-dependent increase in activity induced by serotonin was inhibited in rings from both midterm and term pregnant rats. Conclusions: The reported increase in preterm delivery in women receiving fluoxetine during the third trimester cannot be explained by a direct effect on uterine contractility. (Am J Obstet Gynecol 2000;182:296-9.)

Phospholipase C-delta3 binds with high specificity to phosphatidylinositol 4,5-bisphosphate and phosphatidic acid in bilayer membranes.

In order to acquire an understanding of phospholipase C-delta3 (PLC-delta3) action on substrate localized in lipid membrane we have studied the binding of human recombinant PLC-delta3 to large, unilamellar phospholipid vesicles (LUVs). PLC-delta3 bound weakly to vesicles composed of phosphatidylcholine (PtdCho) or PtdCho plus phosphatidylethanolamine (PtdEtn) or phosphatidylinositol (PtdIns). The enzyme bound strongly to LUVs composed of PtdEtn + PtdCho and phosphatidylinositol 4,5-bisphosphate (PtdInsP2). The binding affinity (molar partition coefficient) of PLC-delta3 to PtdEtn + PtdCho + PtdInsP2 vesicles was 7.7 x 105 m-1. High binding of PLC-delta3 was also observed for LUVs composed of phosphatidic acid (PA). Binding of PLC-delta3 to phosphatidylserine (PtdSer) vesicles was less efficient. Calculated molar partition coefficient for binding of PLC-delta3 to PA and PtdSer vesicles was 1.6 x 104 m-1 and 9.4 x 102 m-1, respectively. Presence of PA in the LUVs containing PtdInsP2 considerably enhanced the binding of PLC-delta3 to the phospholipid membrane. Binding of PLC-delta3 to phospholipid vesicles was not dependent on Ca2+ presence. In the liposome assay PA caused a concentration-dependent increase in activity of PLC-delta3. The stimulatory effect of PA on PLC-delta3 was calcium-dependent. At Ca2+ concentrations lower than 1 microm, no effect of PA on the activity of PLC-delta3 was observed. PA enhanced PLC-delta3 activity by increasing the Vmax and lowering Km for PtdInsP2. As the mol fraction of PA increased from 0-40 mol% the enzyme Vmax increased 2.3-fold and Km decreased threefold. Based on the results presented, we assume that PA supports binding of PLC-delta3 to lipid membranes by interaction with the PH domain of the enzyme. The stimulatory effect of PA depends on calcium-dependent interaction with the C2 domain of PLC-delta3. We propose that binding of PLC-delta3 to PA may serve as a mechanism for dynamic membrane association and modulation of PLC-delta3 activity.