Search results for " phosphatase"
showing 10 items of 329 documents
Particles of vaterite, a metastable CaCO3polymorph, exhibit high biocompatibility for human osteoblasts and endothelial cells and may serve as a biom…
2018
We have previously described a promising alternative to conventional synthetic bone biomaterials using vaterite, a metastable CaCO3 polymorph that increases the local Ca2+ concentration in vitro and leads to an oversaturation of phosphate, the primary bone mineral. This stimulates a natural bone-like mineralisation in a short period of time. In this study, sterile and endotoxin-free vaterite particles were synthesised in a nearly quantitative yield. The 500-1,000 nm vaterite particles did not exhibit any cytotoxic effects as measured by MTS, lactate dehydrogenase, or crystal violet assays on the human osteoblast cell line (MG-63) exposed to concentrations up to 500 μg/ml vaterite up to 72 h…
3D bioprinting of tissue units with mesenchymal stem cells, retaining their proliferative and differentiating potential, in polyphosphate-containing …
2021
Abstract The three-dimensional (3D)-printing processes reach increasing recognition as important fabrication techniques to meet the growing demands in tissue engineering. However, it is imperative to fabricate 3D tissue units, which contain cells that have the property to be regeneratively active. In most bio-inks, a metabolic energy-providing component is missing. Here a formulation of a bio-ink is described, which is enriched with polyphosphate (polyP), a metabolic energy providing physiological polymer. The bio-ink composed of a scaffold (N,O-carboxymethyl chitosan), a hydrogel (alginate) and a cell adhesion matrix (gelatin) as well as polyP substantially increases the viability and the …
Dual effect of inorganic polymeric phosphate/polyphosphate on osteoblasts and osteoclasts in vitro
2012
Inorganic polymeric phosphate/polyphosphate (polyP) is a natural polymer existing in both pro- and eukaryotic systems. In the present study the effect of polyP as well as of polyP supplied in a stoichiometric ratio of 2 m polyP:1 m CaCl2 [polyP (Ca2+ complex)] on the osteoblast-like SaOS-2 cells and the osteoclast-like RAW 264.7 cells was determined. Both polymers are non-toxic for these cells up to a concentration of 100 µm. In contrast to polyP, polyP (Ca2+ complex) significantly induced hydroxyapatite formation at a concentration > 10 µm, as documented by alizarin red S staining and scanning electron microscopic (SEM) inspection. Furthermore, polyP (Ca2+ complex) triggered in SaOS-2 cell…
TORC1 controls G1–S cell cycle transition in yeast via Mpk1 and the greatwall kinase pathway
2015
The target of rapamycin complex 1 (TORC1) pathway couples nutrient, energy and hormonal signals with eukaryotic cell growth and division. In yeast, TORC1 coordinates growth with G1–S cell cycle progression, also coined as START, by favouring the expression of G1 cyclins that activate cyclin-dependent protein kinases (CDKs) and by destabilizing the CDK inhibitor Sic1. Following TORC1 downregulation by rapamycin treatment or nutrient limitation, clearance of G1 cyclins and C-terminal phosphorylation of Sic1 by unknown protein kinases are both required for Sic1 to escape ubiquitin-dependent proteolysis prompted by its flagging via the SCFCdc4 (Skp1/Cul1/F-box protein) ubiquitin ligase complex.…
The effects of alpha-cypermethrin exposure on biochemical and redox parameters in pregnant rats and their newborns
2016
IF 2.388; International audience; Pyrethroid insecticides are extensively used in agriculture and in household activities. During pregnancy, they might affect maternal metabolic status and there after fetal development. In this work, we studied metabolic and redox effects of low dose alpha-cypermethrin exposure in pregnant rats and their offspring. The diet containing alpha cypermethrin at 0.02 mg/kg/day was consumed during the entire gestation. Plasma biochemical parameters as well as liver lipid and oxidative stress markers were determined. Our results showed that alpha-cypermethrin induced an increase in body weight and in plasma glucose and lipid levels, as well as in plasma aspartate a…
The Serine/Threonine Protein Phosphatase 2A (PP2A) Regulates Syk Activity in Human Platelets
2020
Distinct membrane receptors activate platelets by Src-family-kinase (SFK)-, immunoreceptor-tyrosine-based-activation-motif (ITAM)-dependent stimulation of spleen tyrosine kinase (Syk). Recently, we reported that platelet activation via glycoprotein (GP) VI or GPIb&alpha
Deciphering of ADP-induced, phosphotyrosine-dependent signaling networks in human platelets by Src-homology 2 region (SH2)-profiling.
2012
Tyrosine phosphorylation plays a central role in signal transduction controlling many important biological processes. In platelets, the activity of several signaling proteins is controlled by tyrosine phosphorylation ensuring proper platelet activation and aggregation essential for regulation of the delicate balance between bleeding and hemostasis. Here, we applied Src-homology 2 region (SH2)-profiling for deciphering of the phosphotyrosine state of human platelets activated by adenosine diphosphate (ADP). Applying a panel of 31 SH2-domains, rapid and complex regulation of the phosphotyrosine state of platelets was observed after ADP stimulation. Specific inhibition of platelet P2Y receptor…
miR-29b negatively regulates human osteoclastic cell differentiation and function: Implications for the treatment of multiple myeloma-related bone di…
2013
Skeletal homeostasis relies upon a fine tuning of osteoclast (OCLs)-mediated bone resorption and osteoblast (OBLs)-dependent bone formation. This balance is unsettled by multiple myeloma (MM) cells, which impair OBL function and stimulate OCLs to generate lytic lesions. Emerging experimental evidence is disclosing a key regulatory role of microRNAs (miRNAs) in the regulation of bone homeostasis suggesting the miRNA network as potential novel target for the treatment of MM-related bone disease. Here, we report that miR-29b expression decreases progressively during human OCL differentiation in vitro. We found that lentiviral transduction of miR-29b into OCLs, even in the presence of MM cells,…
Osseous response on linear and cyclic RGD-peptides immobilized on titanium surfaces in vitro and in vivo
2017
Biomimetic surface modifications of titanium implants using the Arg-Gly-Asp-sequence (RGD) are promising to accelerate bone healing in cases of medical implants. Therefore, we compared the impact of linear and cyclic RGD (l- and c-RGD) covalently coupled onto titanium surfaces on the osseous response in vitro and in vivo. In vitro, osteoblasts' behaviour on different surfaces (unmodified, amino-silanized (APTES), l- and c-RGD) was analysed regarding adhesion (fluorescence microscopy), proliferation (resazurin stain) and differentiation (RT-PCR on alkaline phosphatase (AP) & osteocalcin (OC)). In vivo, osteosynthesis screws (unmodified n=8, l-RGD n=8, c-RGD n=8) were inserted into the proxim…
Silica as a morphogenetically active inorganic polymer.
2013
At present the scaffolds used for bioprinting of cells do not elicit morphogenetic responses in the cells. In the present study we approached a solution by studying the effect of an inorganic silica supplement added to an Na-alginate matrix. Bone- and osteoblast-like SaOS-2 cells were embedded into this organic polymeric matrix which was additionally enriched with 400 μM prehydrolyzed TEOS [tetra-ethoxy-silane], a source of ortho-silicate. In this silica-based matrix the cells synthesized hydroxyapatite crystallites after exposure to a mineralization activation cocktail composed of β-glycerophosphate, ascorbic acid and dexamethasone. The degree of hydroxyapatite synthesis, determined by sta…