Search results for "CALCIUM"

Phospholipase activities associated with the tonoplast from Acer pseudoplatanus cells: identification of a phospholipase A1 activity

1995

In higher plants, the lipolytic enzymes and their physiological functions are not well characterized [1]. Most reports demonstrated that phospholipid catabolism in plants is achieved by the concerted actions of membrane-bound enzymes including phospholipase D, phosphatidate phosphatase, lipolytic acyl hydrolases and lipoxygenases [1,2]. With the exception of the phospholipase D, the literature on plant phospholipases is still very limited. We previously reported that tonoplast from Acer pseudoplatanus cells contains small amounts of phosphatidc acid and lysophospholipids, which were produced together with free fatty acids, particularly after addition of Ca2+[3]. These data suggested the pos…

Effect of in-office bleaching gels with calcium or fluoride on color, roughness, and enamel microhardness

2019

Background Commercial bleaching gels with remineralizing agents were developed to reduce the adverse effects of dental bleaching. The present study evaluated the effects on teeth of in-office bleaching gels containing 35-40% hydrogen peroxide (HP) with Calcium (Ca) or Fluoride (F). Material and methods Bovine enamel/dentin blocks (4x4x2.5 mm) were randomly divided into the following groups (n=12): no treatment (control); 35% HP (Whiteness HP, FGM); 35% HP with Ca (Whiteness HP Blue, FGM); 40% HP with F (Opalescence Boost, Ultradent). The specimens were analyzed for color (ΔL*, Δa*, Δb*, and ΔE), roughness (Ra), and Knoop microhardness (KHN). The color and KHN data were submitted to ANOVA an…

Impact of Green Vegetables and Green Smoothies on Enamel Mineral Composition In Vitro

2019

Background: Recently, smoothies with a high vegetable content have become very popular, especially among young adults. Objectives: This in vitro study was conducted to determine the erosive potential of selected green vegetables and green smoothies on human dental enamel. Methods: A total of ten green smoothies and eight freshly mixed vegetables were chosen, and pH, calcium and oxalic acid contents were measured. The enamel specimens were obtained from wisdom teeth and incubated with 3 selected foods (spinach, parsley, or green smoothie) for 12 and 24 hours (N = 6). Control samples were incubated with a physiological salt solution. An electron probe microanalyzer (Jeol JXA 8900RL) was utili…

In vitro bioavailability of iron and calcium in cereals and derivatives: A review

2016

Cereals are a staple food in both developed and developing countries, and are considered to be the best vehicle for iron and calcium fortification, as an important strategy for combating dietary deficits. Inadequate dietary intake of iron and calcium is related to a number of disease conditions such as anemia, osteoporosis, hypertension, and different cancers. From a nutritional point of view, it is interesting to know not only the amount of minerals consumed, but also their bioavailability. The present study reviews the current knowledge on the in vitro bioavailability of iron and calcium in cereals, placing emphasis on the methodologies used and on the influence of dietary factors and foo…

Netrin-1 receptor antibodies in thymoma-associated neuromyotonia with myasthenia gravis.

2017

Objective:To identify cell-surface antibodies in patients with neuromyotonia and to describe the main clinical implications.Methods:Sera of 3 patients with thymoma-associated neuromyotonia and myasthenia gravis were used to immunoprecipitate and characterize neuronal cell-surface antigens using reported techniques. The clinical significance of antibodies against precipitated proteins was assessed with sera of 98 patients (neuromyotonia 46, myasthenia gravis 52, thymoma 42; 33 of them with overlapping syndromes) and 219 controls (other neurologic diseases, cancer, and healthy volunteers).Results:Immunoprecipitation studies identified 3 targets, including the Netrin-1 receptors DCC (deleted i…

Sodium functions as a negative allosteric modulator of the oxytocin receptor

2017

Abstract The oxytocin receptor, a class A G protein coupled receptor (GPCR), is essentially involved in the physiology of reproduction. Two parameters are crucially important to support high-affinity agonist binding of the receptor: Mg2+ and cholesterol, both acting as positive modulators. Using displacement assays with a high-affinity fluorescent antagonist (OTAN-A647), we now show that sodium functions as a negative allosteric modulator of the oxytocin receptor. In membranes from HEK293 cells stably expressing the oxytocin receptor, oxytocin binding occurred with about 15-fold lower affinity when sodium chloride was increased from 0 to 300 mM, whereas antagonist binding remained largely u…

2019

The P-STS human ileal neuroendocrine tumor cells, as a model for gut enterochromaffin cells, are strongly and synergistically activated by histamine plus acetylcholine (ACh), presumably via histamine 4 receptors, and weakly activated by histamine alone. Sensing these signals, enterochromaffin cells could participate in intestinal intolerance or allergic reactions to food constituents associated with elevated histamine levels. In this study we aimed to analyze the underlying molecular mechanisms. Inhibition by mepyramine and mibefradil indicated that histamine alone caused a rise in intracellular calcium concentration ([Ca2+]i) via histamine 1 receptors involving T-type voltage-gated calciu…

Palmitoylation is a post-translational modification of Alix regulating the membrane organization of exosome-like small extracellular vesicles.

2018

Abstract Background Virtually all cell types have the capacity to secrete nanometer-sized extracellular vesicles, which have emerged in recent years as potent signal transducers and cell-cell communicators. The multifunctional protein Alix is a bona fide exosomal regulator and skeletal muscle cells can release Alix-positive nano-sized extracellular vesicles, offering a new paradigm for understanding how myofibers communicate within skeletal muscle and with other organs. S-palmitoylation is a reversible lipid post-translational modification, involved in different biological processes, such as the trafficking of membrane proteins, achievement of stable protein conformations, and stabilization…

Direct Sensing of Nutrients via a LAT1-like Transporter in Drosophila Insulin-Producing Cells

2016

Summary Dietary leucine has been suspected to play an important role in insulin release, a hormone that controls satiety and metabolism. The mechanism by which insulin-producing cells (IPCs) sense leucine and regulate insulin secretion is still poorly understood. In Drosophila, insulin-like peptides (DILP2 and DILP5) are produced by brain IPCs and are released in the hemolymph after leucine ingestion. Using Ca2+-imaging and ex vivo cultured larval brains, we demonstrate that IPCs can directly sense extracellular leucine levels via minidiscs (MND), a leucine transporter. MND knockdown in IPCs abolished leucine-dependent changes, including loss of DILP2 and DILP5 in IPC bodies, consistent wit…

Oxidative stress modulates rearrangement of endoplasmic reticulum-mitochondria contacts and calcium dysregulation in a Friedreich's ataxia model

2020

Friedreich ataxia (FRDA) is a neurodegenerative disorder characterized by neuromuscular and neurological manifestations. It is caused by mutations in the FXN gene, which results in loss of the mitochondrial protein frataxin. Endoplasmic Reticulum-mitochondria associated membranes (MAMs) are inter-organelle structures involved in the regulation of essential cellular processes, including lipid metabolism and calcium signaling. In the present study, we have analyzed in both, unicellular and multicellular models of FRDA, calcium management and integrity of MAMs. We observed that function of MAMs is compromised in our cellular model of FRDA, which was improved upon treatment with antioxidants. I…