Microbicidal action of lactoferrin and lactoferricin and their synergistic effect with metronidazole inEntamoeba histolyticaThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal's usual peer review process.

2006 ◽  
Vol 84 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Nidia León-Sicairos ◽  
Magda Reyes-López ◽  
Cynthia Ordaz-Pichardo ◽  
Mireya de la Garza
Keyword(s):  
Peer Review Process ◽  
Divalent Cations ◽  
Free Form ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
New Agents ◽  
Killing Effect ◽  
Bovine Lactoferricin ◽  
Amoebicidal Effect ◽  
Selection Of

Lactoferrin (Lf), in its iron-free form, has been shown to inhibit the growth of pathogenic microorganisms. In the light of new agents to control amoebiasis, the microbicidal activity of human and bovine Lf and bovine lactoferricin (bLfcin, fragment 4–14), and of each combined with metronidazole, the main drug used in amoebiasis, was evaluated in trophozoites of Entamoeba histolytica. Both lactoferrins and bLfcin were able to kill amoebas in a concentration-dependent manner. This killing effect was modulated according to the culture age, pH, and temperature. Parasites obtained from the stationary phase were more susceptible to Lf than those from the early exponential phase. The effect of Lf and its derived peptide, bLfcin, was prevented by both Fe2+and Fe3+. However, the divalent cations Mg2+and Ca2+prevented the killing effect of Lf but not of bLfcin. A synergistic amoebicidal effect was found between metronidazole and human Lf, bovine Lf, or bLfcin. These data suggest that Lf and bLfcin might be used in amoebiasis if they are administered with a low dose of metronidazole to diminish the toxicity of this drug. Thus, Lf and bLfcin are therapeutically potential candidates for use as antiamoebics in patients.

scholarly journals Genotypic differences in response to Hygromycin effect on untransformed calli death and rice germination

2015 ◽  
Vol 18 (1-2) ◽  
pp. 38-43 ◽  
Author(s):  
Shahanaz Sultana ◽  
Chai Ling Ho ◽  
Parameswari Namasivayam ◽  
Suhaimi Napis
Keyword(s):  
Root Growth ◽  
Oryza Sativa L ◽  
Genotypic Differences ◽  
Dependent Manner ◽  
Growth Reduction ◽  
Rice Varieties ◽  
Concentration Dependent Manner ◽  
Percent Germination ◽  
Shoot And Root Growth ◽  
Selection Of

Hygromycin is an efficient selective agent in transformation studies of wide ranges of crop. In this study, different concentrations of hygromycin were used to observe the effect on untransformed calli death, percent germination and seedling growth of three rice varieties (Oryza sativa L.) viz BRRI dhan29, MR219 and Taipei309. Hygromycin killed the untransformed calli and inhibited the germination of tested varieties in a concentration dependent manner. Among the tested varieties, the lowest and the highest calli death was observed in MR219 and Taipei309 respectively in all the concentrations of hygromycin. Whereas, the highest and the lowest percent germination were observed in MR219 and Taipei309 respectively. The minimal inhibitory concentration (MIC) for selection of calli were calculated as 42, 40 and 47 mg/L hygromycin for BRRI dhan29, MR219 and Taipei309 respectively. During germination, 35, 62 and 32 mg/L hygromycin were suitable for the selection of BRRI dhan29, MR219 and Taipei 309 respectively. Shoot and root growth reduction after germination was increased with the increased concentration of hygromycin. Besides, root growth was more sensitive to hygromycin than the shoot. These results suggest that hygromycin increases calli death, decreases percent germination, and shoot and root growth in all varieties with the increasing rate of hygromycin. But these characteristics vary with different degrees in different genotypes as well as different stages.Bangladesh Rice j. 2014, 18(1&2): 38-43

scholarly journals Effect of the divalent cations zinc and calcium on the structure and mechanics of reconstituted vimentin intermediate filaments

2019 ◽  
Author(s):  
Huayin Wu ◽  
Yinan Shen ◽  
Dianzhuo Wang ◽  
Harald Herrmann ◽  
Robert D. Goldman ◽  
...  
Keyword(s):  
Intermediate Filaments ◽  
Network Structure ◽  
Protein Interactions ◽  
Divalent Cations ◽  
Dependent Manner ◽  
Structural Elements ◽  
Concentration Dependent Manner ◽  
Hofmeister Effect ◽  
Ion Species

AbstractDivalent cations in a concentration-dependent manner behave as effective crosslinkers of intermediate filaments (IFs) such as vimentin IF (VIF). These interactions have been mostly attributed to their multivalency. However, ion-protein interactions often depend on the ion species, and these effects have not been widely studied in IFs. Here we investigate the effects of two biologically important divalent cations, Zn2+ and Ca2+, on VIF network structure and mechanics in vitro. We find that the network structure is unperturbed at micromolar Zn2+ concentrations, but strong bundle formation is observed at a concentration of 100 μM. Microrheological measurements show that network stiffness increases with cation concentration. However, bundling of filaments softens the network. This trend also holds for VIF networks formed in the presence of Ca2+, but remarkably, a concentration of Ca2+ that is two orders higher is needed to achieve the same effect as with Zn2+, which suggests the importance of salt-protein interactions as described by the Hofmeister effect. Furthermore, we find evidence of competitive binding between the two divalent ion species. Hence, specific interactions between VIFs and divalent cations are likely to be an important mechanism by which cells can control their cytoplasmic mechanics.SignificanceIntermediate filaments are key structural elements within cells; they are known to form networks that can be crosslinked by divalent cations, but the interactions between the ions and the filaments are not well understood. By measuring the effects that two divalent cations, zinc and calcium, have on the structure and mechanics of vimentin intermediate filaments (VIFs), we show that although both have concentration-dependent effects on VIFs, much more calcium is needed to achieve the same effect as a small amount of zinc. Furthermore, when mixtures of the ions are present, the results suggest that there is binding competition. Thus, cells may use the presence of different cation species to precisely control their internal mechanical properties.

scholarly journals Polyvalent Cations Constitute the Voltage Gating Particle in Human Connexin37 Hemichannels

2004 ◽  
Vol 124 (5) ◽  
pp. 587-603 ◽  
Author(s):  
Michael C. Puljung ◽  
Viviana M. Berthoud ◽  
Eric C. Beyer ◽  
Dorothy A. Hanck
Keyword(s):  
Divalent Cations ◽  
Voltage Gating ◽  
Bathing Solution ◽  
Local Concentration ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Current Decay ◽  
Gap Junction Channel ◽  
Polyvalent Cations ◽  
Voltage Dependent

Connexins oligomerize to form intercellular channels that gate in response to voltage and chemical agents such as divalent cations. Historically, these are believed to be two independent processes. Here, data for human connexin37 (hCx37) hemichannels indicate that voltage gating can be explained as block/unblock without the necessity for an independent voltage gate. hCx37 hemichannels closed at negative potentials and opened in a time-dependent fashion at positive potentials. In the absence of polyvalent cations, however, the channels were open at relatively negative potentials, passing current linearly with respect to voltage. Current at negative potentials could be inhibited in a concentration-dependent manner by the addition of polyvalent cations to the bathing solution. Inhibition could be explained as voltage-dependent block of hCx37, with the field acting directly on polyvalent cations, driving them through the pore to an intracellular site. At positive potentials, in the presence of polyvalent cations, the field favored polyvalent efflux from the intracellular blocking site, allowing current flow. The rate of appearance of current depended on the species and valence of the polyvalent cation in the bathing solution. The rate of current decay upon repolarization depended on the concentration of polyvalent cations in the bathing solution, consistent with deactivation by polyvalent block, and was rapid (time constants of tens of milliseconds), implying a high local concentration of polyvalents in or near the channel pore. Sustained depolarization slowed deactivation in a flux-dependent, voltage- and time-independent fashion. The model for hCx37 voltage gating as polyvalent block/unblock can be expanded to account for observations in the literature regarding hCx37 gap junction channel behavior.

scholarly journals 1,25(OH)2D3 stimulates Mg2+uptake into MDCT cells: modulation by extracellular Ca2+and Mg2+

2001 ◽  
Vol 280 (5) ◽  
pp. F868-F878 ◽  
Author(s):  
Gordon Ritchie ◽  
Dirk Kerstan ◽  
Long-Jun Dai ◽  
Hyung Sub Kang ◽  
Lucie Canaff ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
De Novo ◽  
Divalent Cations ◽  
Gene Activation ◽  
Peptide Hormone ◽  
Distal Convoluted Tubule ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Dihydroxyvitamin D ◽  
Magnesium Uptake

The distal convoluted tubule plays a significant role in renal magnesium conservation. Although the cells of the distal convoluted tubule possess the vitamin D receptor, little is known about the effects of 1α,25-dihydroxyvitamin D [1,25(OH)2D3] on magnesium transport. In this study, we examined the effect of 1,25(OH)2D3 on distal cellular magnesium uptake and the modulation of this response by extracellular Ca2+and Mg2+ in an immortalized mouse distal convoluted tubule (MDCT) cell line. MDCT cells possess the divalent cation-sensing receptor (CaSR) that responds to elevation of extracellular Ca2+ and Mg2+ concentrations to diminish peptide hormone-stimulated Mg2+ uptake. Mg2+uptake rates were determined by microfluorescence in Mg2+-depleted MDCT cells. Treatment of MDCT cells with 1,25(OH)2D3 for 16–24 h stimulated basal Mg2+ uptake in a concentration-dependent manner from basal levels of 164 ± 5 to 210 ± 11 nM/s, representing a 28 ± 3% change. Pretreatment with actinomycin D or cycloheximide abolished 1,25(OH)2D3-stimulated.Mg2+uptake (154 ± 18 nM/s), suggesting that 1,25(OH)2D3 stimulates Mg2+ uptake through gene activation and protein synthesis. Elevation of extracellular Ca2+ inhibited 1,25(OH)2D3-stimulated Mg2+ uptake (143 ± 5 nM/s). Preincubation of the cells with an antibody to the CaSR prevented the inhibition by elevated extracellular Ca2+ of 1,25(OH)2D3-stimulated Mg2+ uptake (202 ± 8 nM/s). Treatment with an antisense CaSR mRNA oligodeoxynucleotide also abolished the effects of extracellular Ca2+ on 1,25(OH)2D3-responsive Mg2+ entry. This showed that elevated extracellular calcium modulates 1,25(OH)2D-mediated responses through the CaSR. In summary, 1,25(OH)2D3 stimulated Mg2+ uptake in MDCT cells, and this is dependent on de novo protein synthesis. Elevation of extracellular Ca2+, acting via the CaSR, inhibited 1,25(OH)2D3-stimulated Mg2+ entry. These data indicate that 1,25(OH)2D3 has important effects on the control of magnesium entry in MDCT cells and these responses can be modulated by extracellular divalent cations.

Stimulatory effects of neuronally released norepinephrine on renin release in vitro

1988 ◽  
Vol 255 (4) ◽  
pp. F614-F620
Author(s):  
Y. Matsumura ◽  
S. Kawazoe ◽  
T. Ichihara ◽  
H. Shinyama ◽  
M. Kageyama ◽  
...  
Keyword(s):  
Divalent Cations ◽  
Rat Kidney ◽  
Sympathetic Nerves ◽  
Renin Release ◽  
Dependent Manner ◽  
High Potassium ◽  
Concentration Dependent Manner ◽  
Release In Vitro ◽  
Renal Sympathetic

Extracellular high potassium inhibits renin release in vitro by increasing calcium concentrations in the juxtaglomerular cells. We found that the decreased response of renin release from rat kidney cortical slices in high potassium solution (20-80 mM) changed to a strikingly increased one in the presence of nifedipine at doses over 10(-6) M. We then examined the stimulatory effect of extracellular high potassium in the presence of nifedipine on renin release. The enhancement of release was significantly suppressed either by propranolol or by metoprolol but not by prazosin. High potassium plus nifedipine-induced increase in renin release was markedly attenuated by renal denervation. The enhancing effect was not observed when the slices were incubated in calcium-free medium. Divalent cations such as Cd2+, Co2+, and Mn2+ (0.1-3.0 mM) blocked this enhancement in a concentration-dependent manner. High potassium elicited an increase in 3H efflux from the slices preloaded with [3H]norepinephrine. The increasing effect was not influenced by nifedipine but was abolished by the removal of extracellular calcium or by the addition of divalent cations. These observations suggest to us that the high potassium plus nifedipine-induced increase in renin release from the slices is mediated by norepinephrine derived from renal sympathetic nerves and that this neuronally released norepinephrine stimulates renin release via activation of beta-adrenoceptors.

Effects of N-n-butyl haloperidol iodide on L-type calcium channels and intracellular free calcium in rat ventricular myocytesThis paper is one of a selection of papers in this Special Issue, entitled International Symposium on Recent Advances in Molecular, Clinical, and Social Medicine, and has undergone the Journal's usual peer-review process.

2007 ◽  
Vol 85 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Zhanqin Huang ◽  
Ganggang Shi ◽  
Fenfei Gao ◽  
Yanmei Zhang ◽  
Xingping Liu ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Calcium Release ◽  
Peer Review Process ◽  
Intracellular Free Calcium ◽  
Inactivation Kinetics ◽  
Free Calcium ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Fluorescent Intensity

The ability of N-n-butyl haloperidol iodide (F2) to cause vasodilation, and thereby produce a cardioprotective effect, has been well documented. The aim of this study was to investigate whether F2 might act as a Ca2+ antagonist. Myocytes were obtained from rat heart, and the whole-cell patch-clamp technique was used to record Ca2+ current. Laser scanning confocal microscopy was used to measure intracellular free calcium ([Ca2+]i). The results obtained from this study demonstrate that F2 reduced calcium current (ICa) in a concentration-dependent manner with an IC50 of 1.19 µmol/L, upshifted the current-voltage curve of ICa, shifted the inactivation kinetics of ICa leftward, and slowed down the recovery of ICa from inactivation. F2 decreased the fluorescent intensity of [Ca2+]i elevation induced by KCl with an IC50 of 1.61 µmol/L, and had no effects on the intracellular calcium release induced by caffeine and inositol-1,4,5-trisphosphate. These findings indicate that F2 may act as a calcium antagonist, which could account for its cardiovascular benefits.

MeCP2: structure and functionThis paper is one of a selection of papers published in a Special Issue entitled 31st Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Nicholas L. Adkins ◽  
Philippe T. Georgel
Keyword(s):  
Current Knowledge ◽  
Peer Review Process ◽  
Regulation Of Gene Expression ◽  
Dependent Manner ◽  
Structural Domains ◽  
Architectural Proteins ◽  
Protein Mecp2 ◽  
Selection Of

Despite a vast body of literature linking chromatin structure to regulation of gene expression, the role of architectural proteins in higher order chromatin transitions required for transcription activation and repression has remained an under-studied field. To demonstrate the current knowledge of the role of such proteins, we have focused our attention on the methylated DNA binding and chromatin-associated protein MeCP2. Structural studies using chromatin assembled in vitro have revealed that MeCP2 can associate with nucleosomes in an N-terminus dependent manner and efficiently condense nucleosome arrays. The present review attempts to match MeCP2 structural domains, or lack thereof, and specific chromatin features needed for the proper recruitment of MeCP2 to its multiple functions as either activator or repressor. We specifically focused on MeCP2’s role in Rett syndrome, a neurological disorder associated with specific MeCP2 mutations.

The Anti-Atherogenic Properties of Sesamin are Mediated via Improved Macrophage Cholesterol Efflux Through PPARγ1-LXRα and MAPK Signaling

2014 ◽  
Vol 84 (1-2) ◽  
pp. 79-91 ◽  
Author(s):  
Amin F. Majdalawieh ◽  
Hyo-Sung Ro
Keyword(s):  
Cholesterol Efflux ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Foam Cell ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Macrophage Cholesterol Efflux

Background: Foam cell formation resulting from disrupted macrophage cholesterol efflux, which is triggered by PPARγ1 and LXRα, is a hallmark of atherosclerosis. Sesamin and sesame oil exert anti-atherogenic effects in vivo. However, the exact molecular mechanisms underlying such effects are not fully understood. Aim: This study examines the potential effects of sesamin (0, 25, 50, 75, 100 μM) on PPARγ1 and LXRα expression and transcriptional activity as well as macrophage cholesterol efflux. Methods: PPARγ1 and LXRα expression and transcriptional activity are assessed by luciferase reporter assays. Macrophage cholesterol efflux is evaluated by ApoAI-specific cholesterol efflux assays. Results: The 50 μM, 75 μM, and 100 μM concentrations of sesamin up-regulated the expression of PPARγ1 (p< 0.001, p < 0.001, p < 0.001, respectively) and LXRα (p = 0.002, p < 0.001, p < 0.001, respectively) in a concentration-dependent manner. Moreover, 75 μM and 100 μM concentrations of sesamin led to 5.2-fold (p < 0.001) and 6.0-fold (p<0.001) increases in PPAR transcriptional activity and 3.9-fold (p< 0.001) and 4.2-fold (p < 0.001) increases in LXR transcriptional activity, respectively, in a concentration- and time-dependent manner via MAPK signaling. Consistently, 50 μM, 75 μM, and 100 μM concentrations of sesamin improved macrophage cholesterol efflux by 2.7-fold (p < 0.001), 4.2-fold (p < 0.001), and 4.2-fold (p < 0.001), respectively, via MAPK signaling. Conclusion: Our findings shed light on the molecular mechanism(s) underlying sesamin’s anti-atherogenic effects, which seem to be due, at least in part, to its ability to up-regulate PPARγ1 and LXRα expression and transcriptional activity, improving macrophage cholesterol efflux. We anticipate that sesamin may be used as a therapeutic agent for treating atherosclerosis.

Neutrophil Elastase Potentiates Cathepsin G-lnduced Platelet Activation

1992 ◽  
Vol 68 (05) ◽  
pp. 570-576 ◽  
Author(s):  
Mary A Selak
Keyword(s):  
Neutrophil Elastase ◽  
Cell Activation ◽  
Thromboxane A2 ◽  
Creatine Phosphate ◽  
Dense Granule ◽  
Cathepsin G ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Low Concentrations ◽  
High Concentrations

SummaryWe have previously demonstrated that human neutrophil cathepsin G is a strong platelet agonist that binds to a specific receptor. This work describes the effect of neutrophil elastase on cathepsin G-induced platelet responses. While platelets were not activated by high concentrations of neutrophil elastase by itself, elastase enhanced aggregation, secretion and calcium mobilization induced by low concentrations of cathepsin G. Platelet aggregation and secretion were potentiated in a concentration-dependent manner by neutrophil elastase with maximal responses observable at 200 nM. Enhancement was observed when elastase was preincubated with platelets for time intervals of 10–60 s prior to addition of a low concentration of cathepsin G and required catalytically-active elastase since phenylmethanesulphonyl fluoride-inhibited enzyme failed to potentiate cell activation. Neutrophil elastase potentiation of platelet responses induced by low concentrations of cathepsin G was markedly inhibited by creatine phosphate/creatine phosphokinase and/or indomethacin, indicating that the synergism between elastase and cathepsin G required the participation of ADP and thromboxane A2. On the other hand, platelet responses were not attenuated by the PAF antagonist BN 52021, signifying that PAF-acether did not play a role in elastase potentiation. At higher concentrations porcine pancreatic elastase exhibits similar effects to neutrophil elastase, demonstrating that the effect of elastase was not unique to the neutrophil protease. While neutrophil elastase failed to alter the ability of cathepsin G to hydrolyze a synthetic chromogenic substrate, preincubation of platelets with elastase increased the apparent affinity of cathepsin G binding to platelets. In contrast to their effect on cathepsin G-induced platelet responses, neither neutrophil nor pancreatic elasatse potentiated aggregation or dense granule release initiated by ADP, PAF-acether, arachidonic acid or U46619, a thromboxane A2 mimetic. Moreover, unlike its effect on cathepsin G, neutrophil elastase inhibited thrombin-induced responses. The current observations demonstrate that elastase can potentiate platelet responses mediated by low concentrations of cathepsin G, suggesting that both enzymes may function synergistically to activate platelets under conditions where neutrophil degranulation occurs.

Trimucytin: A Collagen-Like Aggregating Inducer Isolated from Trimeresurus mucrosquamatus Snake Venom

1993 ◽  
Vol 69 (03) ◽  
pp. 286-292 ◽  
Author(s):  
Che-Ming Teng ◽  
Feng-Nien Ko ◽  
Inn-Ho Tsai ◽  
Man-Ling Hung ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Snake Venom ◽  
Inositol Phosphate ◽  
Shape Change ◽  
Platelet Activating Factor ◽  
Atp Release ◽  
Platelet Membrane ◽  
Thromboxane B2 ◽  
Dependent Manner ◽  
Concentration Dependent Manner

SummaryTrimucytin is a potent platelet aggregation inducer isolated from Trimeresurus mucrosquamatus snake venom. Similar to collagen, trimucytin has a run of (Gly-Pro-X) repeats at the N-terminal amino acids sequence. It induced platelet aggregation, ATP release and thromboxane formation in rabbit platelets in a concentration-dependent manner. The aggregation was not due to released ADP since it was not suppressed by creatine phosphate/creatine phosphokinase. It was not either due to thromboxane A2 formation because indomethacin and BW755C did not have any effect on the aggregation even thromboxane B2 formation was completely abolished by indomethacin. Platelet-activating factor (PAF) was not involved in the aggregation since a PAF antagonist, kadsurenone, did not affect. However, RGD-containing peptide triflavin inhibited the aggregation, but not the release of ATP, of platelets induced by trimucytin. Indomethacin, mepacrine, prostaglandin E1 and tetracaine inhibited the thromboxane B2 formation of platelets caused by collagen and trimucytin. Forskolin and sodium nitroprusside inhibited both platelet aggregation and ATP release, but not the shape change induced by trimucytin. In quin-2 loaded platelets, the rise of intracellular calcium concentration caused by trimucytin was decreased by 12-O-tetradecanoyl phorbol-13 acetate, imipramine, TMB-8 and indomethacin. In the absence of extracellular calcium, both collagen and trimucytin caused no thromboxane B2 formation, but still induced ATP release which was completely blocked by R 59022. Inositol phosphate formation in platelets was markedly enhanced by trimucytin and collagen. MAB1988, an antibody against platelet membrane glycoprotein Ia, inhibited trimucytinand collagen-induced platelet aggregation and ATP release. However, trimucytin did not replace the binding of 125I-labeled MAB1988 to platelets. Platelets pre-exposed to trimucytin were resistant to the second challenge with trimucytin itself or collagen. It is concluded that trimucytin may activate collagen receptors on platelet membrane, and cause aggregation and release mainly through phospholipase C-phosphoinositide pathway.

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