Search results for "CALCIUM"
showing 10 items of 1740 documents
[68Ga]Ga-THP-Pam: A Bisphosphonate PET Tracer with Facile Radiolabeling and Broad Calcium Mineral Affinity
2020
Calcium minerals such as hydroxyapatite (HAp) can be detected non-invasively in vivo using nuclear imaging agents such as [18F]NaF (available from cyclotrons), for positron emission tomography (PET) and 99mTc-radiolabelled bisphosphonates (BP; available from 99mTc generators for single photon emission computed tomography (SPECT) or scintigraphy). These two types of imaging agents allow detection of bone metastases (based on the presence of HAp) and vascular calcification lesions (that contain HAp and other calcium minerals). With the aim of developing a cyclotron-independent PET radiotracer for these lesions, with broad calcium mineral affinity and simple one-step radiolabelling, we develop…
The Link between Oxidative Stress, Redox Status, Bioenergetics and Mitochondria in the Pathophysiology of ALS
2021
Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative disease of the motor system. It is characterized by the degeneration of both upper and lower motor neurons, which leads to muscle weakness and paralysis. ALS is incurable and has a bleak prognosis, with median survival of 3–5 years after the initial symptomatology. In ALS, motor neurons gradually degenerate and die. Many features of mitochondrial dysfunction are manifested in neurodegenerative diseases, including ALS. Mitochondria have shown to be an early target in ALS pathophysiology and contribute to disease progression. Disruption of their axonal transport, excessive generation of reactive oxygen species, disruptio…
Calcium, Iron, and Zinc Uptake from Digests of Infant Formulas by Caco-2 Cells
2001
Our aim was to estimate the bioavailability of calcium, iron, and zinc from infant formulas using a model that includes in vitro digestion and a Caco-2 cell culture to estimate the uptake. The cell culture conditions were selected, and uptake assays were carried out first with calcium, iron, and zinc standard solutions, and then with the soluble fraction of enzymatic digests of an adapted milk-based and a soy-based infant formula. It was not possible to measure the uptake of calcium, iron, and zinc from standard solutions added to the cell cultures in amounts similar to those present in infant formula digests with our method. The fact that it was, however, possible in the case of enzymatic …
Synthesis of calcium carbonate biological materials: how many proteins are needed?
2013
In Nature, calcium carbonate biomineralizations are the most abundant mineralized structures of biological origin. Because many exhibit remarkable characteristics, several attempts have been made to use them as substitution materials for bone reconstruction or as models for generating biomimetic composites that exhibit tailored properties. CaCO3biomineralizations contain small amounts of amalgamate of proteins and polysaccharides that are secreted during the calcification process. They contribute to control the morphology of the crystallites and to spatially organize them in well-defined microstructures. These macromolecules, collectively defined as the skeletal matrix, have been the focus …
Evolution and biomineralization of pteropod shells
2021
12 pages; International audience; Shelled pteropods, known as sea butterflies, are a group of small gastropods that spend their entire lives swimming and drifting in the open ocean. They build thin shells of aragonite, a metastable polymorph of calcium carbonate. Pteropod shells have been shown to experience dissolution and reduced thickness with a decrease in pH and therefore represent valuable bioindicators to monitor the impacts of ocean acidification. Over the past decades, several studies have highlighted the striking diversity of shell microstructures in pteropods, with exceptional mechanical properties, but their evolution and future in acidified waters remains uncertain. Here, we re…
Compartmentalization of gypsum and halite associated with cyanobacteria in saline soil crusts
2016
The interface between biological and geochemical components in surface crust of a saline soil was investigated using X-Ray Diffraction (XRD), and variable pressure scanning electron microscopy (SEM) in combination with Energy Dispersive X-ray Spectrometry (EDS). Mineral compounds such as halite and gypsum were identified crystallized around filaments of cyanobacteria. A total of 92 genera were identified from the bacterial community based on 16S gene pyrosequencing analysis. The occurrence of the gypsum crystals, their shapes and compartmentalization suggested that they separated NaCl from the immediate microenvironment of the cyanobacteria, and that some cyanobacteria and communities of su…
Genesis of amorphous calcium carbonate containing alveolar plates in the ciliate Coleps hirtus (Ciliophora, Prostomatea).
2013
7 pages; International audience; In the protist world, the ciliate Coleps hirtus (phylum Ciliophora, class Prostomatea) synthesizes a peculiar biomineralized test made of alveolar plates, structures located within alveolar vesicles at the cell cortex. Alveolar plates are arranged by overlapping like an armor and they are thought to protect and/or stiffen the cell. Although their morphology is species-specific and of complex architecture, so far almost nothing is known about their genesis, their structure and their elemental and mineral composition. We investigated the genesis of new alveolar plates after cell division and examined cells and isolated alveolar plates by electron microscopy, e…
Climate variation during the Holocene influenced the skeletal properties of Chamelea gallina shells in the North Adriatic Sea (Italy)
2021
Understanding how marine taxa will respond to near-future climate changes is one of the main challenges for management of coastal ecosystem services. Ecological studies that investigate relationships between the environment and shell properties of commercially important marine species are commonly restricted to latitudinal gradients or small-scale laboratory experiments. This paper aimed to explore the variations in shell features and growth of the edible bivalve Chamelea gallina from the Holocene sedimentary succession to present-day thanatocoenosis of the Po Plain-Adriatic Sea system (Italy). Comparing the Holocene sub-fossil record to modern thanatocoenoses allowed obtaining an insight o…
Phosphorylation of serine residues is fundamental for the calcium-binding ability of Orchestin, a soluble matrix protein from crustacean calcium stor…
2003
International audience; Orchestia cavimana is a terrestrial crustacean, which cyclically stores calcium in diverticula of the midgut, in the form of calcified amorphous concretions. These concretions are associated with a proteinaceous matrix, the main constituent of the soluble matrix is Orchestin, an acidic calcium-binding protein [Testenière et al., Biochem. J. 361 (2002) 327-335]. In the present paper, we clearly demonstrate that Orchestin is phosphorylated on serine and tyrosine residues, but that calcium binding only occurs via the phosphoserine residues. To our knowledge, this is the first example of an invertebrate mineralization for which a post-translational modification is clearl…
The shell organic matrix of the crossed lamellar queen conch shell (Strombus gigas)
2014
10 pages; International audience; In molluscs, the shell organic matrix comprises a large set of biomineral-occluded proteins, glycoproteins and polysaccharides that are secreted by the calcifying mantle epithelium, and are supposed to display several functions related to the synthesis of the shell. In the present paper, we have characterized biochemically the shell matrix associated to the crossed-lamellar structure of the giant queen conch Strombus gigas. The acid-soluble (ASM) and acid-insoluble (AIM) matrices represent an extremely minor fraction of the shell. Both are constituted of polydisperse and of few discrete proteins among which three fractions, obtained by preparative SDS-PAGE …