Search results for "ATS"
showing 10 items of 6881 documents
Amorphous polyphosphate/amorphous calcium carbonate implant material with enhanced bone healing efficacy in a critical-size defect in rats
2016
In this study the effect of amorphous calcium carbonate (ACC) microparticles and amorphous calcium polyphosphate (polyP) microparticles (termed aCa-polyP-MP) on bone mineral forming cells/tissue was investigated in vitro and in vivo. The ACC particles (termed ACC-P10-MP) were prepared in the presence of Na-polyP. Only the combinations of polyP and ACC microparticles enhanced the proliferation rate of human mesenchymal stem cells (MSCs). Gene expression studies revealed that ACC causes an upregulation of the expression of the cell membrane-associated carbonic anhydrase IX (CA IX; formation of ACC), while the transcript level of the alkaline phosphatase (ALP; liberation of orthophosphate from…
Histological evaluation of bone repair using beta-Tricalcium Phosphate
2010
Objectives: The aim of the present study was to evaluate bone repair in defects induced in the cranium of Wistar rats using ?-tricalcium phosphate. Study Design: In this research, we used 30 rats, randomly distributed in three groups of 10 animals (G1, G2 and G3), corresponding respectively to time of histological evaluation (7, 15 and 30 days). This was a paired study, a defect being induced in the parietal bone on either side of the median sagittal suture of the animals, being the left-hand side the experimental subgroup (filled by biomaterial) and the right control. The histological evaluation was performed by means of light microscopy. The collected data were submitted to the Fisher Exa…
Influence of β-tricalcium phosphate granule size and morphology on tissue reaction in vivo.
2010
In this study the tissue reaction to five different β-tricalcium phosphate (β-TCP)-based bone substitute materials differing only in size, shape and porosity was analyzed over 60 days, at 3, 10, 15, 30 and 60 days after implantation. Using the subcutaneous implantation model in Wistar rats both the inflammatory response within the implantation bed and the resulting vascularization of the biomaterials were qualitatively and quantitatively assessed by means of standard and special histological staining methods. The data from this study showed that all investigated β-TCP bone substitutes induced the formation of multinucleated giant cells. Changes in size, shape and porosity influenced the int…
Implantation of silicon dioxide-based nanocrystalline hydroxyapatite and pure phase beta-tricalciumphosphate bone substitute granules in caprine musc…
2012
Abstract Background Osteoinductive bone substitutes are defined by their ability to induce new bone formation even at heterotopic implantation sites. The present study was designed to analyze the potential osteoinductivity of two different bone substitute materials in caprine muscle tissue. Materials and methods One gram each of either a porous beta-tricalcium phosphate (β-TCP) or an hydroxyapatite/silicon dioxide (HA/SiO2)-based nanocrystalline bone substitute material was implanted in several muscle pouches of goats. The biomaterials were explanted at 29, 91 and 181 days after implantation. Conventional histology and special histochemical stains were performed to detect osteoblast precurs…
Short time guided bone regeneration using beta-tricalcium phosphate with and without fibronectin. An experimental study in rats
2020
Background The aim of this histomorphometric study was to assess the bone regeneration potential of beta-tricalcium phosphate with fibronectin (β-TCP-Fn) in critical-sized defects (CSDs) in rats calvarial, to know whether Fn improves the new bone formation in a short time scope. Material and Methods CSDs were created in 30 Sprague Dawley rats, and divided into four groups (2 or 6 weeks of healing) and type of filling (β-TCP-Fn, β-TCP, empty control). Variables studied were augmented area (AA), gained tissue (GT), mineralized/non mineralized bone matrix (MBM/NMT) and bone substitute (BS). Results 60 samples at 2 and six weeks were evaluated. AA was higher for treatment groups comparing to …
Induction of the alkyltransferase (MGMT) gene by DNA damaging agents and the glucocorticoid dexamethasone and comparison with the response of base ex…
1996
Repair of alkylated bases in DNA is performed by O6-methylguanine-DNA methyltransferase (MGMT) and a set of enzymes of the base excision repair pathway involving N-methylpurine-DNA glycosylase (MPG), apurinic endonuclease (APE), DNA polymerase beta (Pol beta) and DNA ligase. The level of expression of these enzymes may exert a profound effect on resistance of cells towards alkylating drugs. We have comparatively analyzed the expression of MGMT and the different base excision repair genes in rat hepatoma cells (line H4IIE) after exposure to alkylating agents, X-rays and the glucocorticoid hormone dexamethasone. Furthermore, the effect of these agents on the activity of the cloned human MGMT …
Interference of L-arginine analogues with L-arginine transport mediated by the y+ carrier hCAT-2B.
1997
The inducible human cationic amino acid transporter hCAT-2B was expressed in Xenopus laevis oocytes, and this system was used to test the effect of several NO synthase (NOS) inhibitors and/or L-arginine analogues on L-arginine transport by this y+ carrier. L-NG-Methyl-L-arginine (L-NMA), asymmetrical L-NG, NG-dimethyl-L-arginine (L-ADMA), L-N5-(1-iminoethyl)-ornithine (L-NIO), L-NG-nitro-L-arginine (L-NNA), and L-NG-nitro-L-arginine methyl ester (L-NAME) all inhibited the inducible NOS II extracted from RAW 264.7 macrophages induced with bacterial lipopolysaccharide. L-NMA, L-ADMA, and L-NIO also competed with L-arginine for transport by hCAT-2B, whereas L-NNA and L-NAME did not. The two L-…
The in vitro metabolic activation of dibenz[a,h]anthracene, catalyzed by by rat liver microsomes and examined by 32P-postlabelling.
1991
DNA has been incubated in vitro with dibenz[a,h]anthracene (DB[a,H]A) and the related 5,6-diol and 3,4-diol in the presence of 3-methylcholanthrene- or Aroclor 1254-induced rat liver microsomes. After incubation, the DNA was extracted and examined for the presence of aromatic adducts using the nuclease P1 modification of the 32P-postlabelling technique. The maps of PEI-cellulose plates and autoradiography showed that 92% of the radioactivity contained in DB[a,h]A-DNA adduct spots is derived from the related 3,4-diol and that about 50% of the adducts may be formed following the conversion of this diol to the bay-region anti- and syn-3,4-diol 1,2-oxides.
TCDD deregulates contact inhibition in rat liver oval cells via Ah receptor, JunD and cyclin A.
2007
The aryl hydrocarbon receptor (AhR) is a transcription factor involved in physiological processes, but also mediates most, if not all, toxic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Activation of the AhR by TCDD leads to its dimerization with aryl hydrocarbon nuclear translocator (ARNT) and transcriptional activation of several phase I and II metabolizing enzymes. However, this classical signalling pathway so far failed to explain the pleiotropic hazardous effects of TCDD, such as developmental toxicity and tumour promotion. Thus, there is an urgent need to define genetic programmes orchestrated by AhR to unravel its role in physiology and toxicology. Here we show that TCDD …
Malignant transformation of the liver tumour precursor cell line OC/CDE 22 by the four stereoisomeric fjord region 3,4-dihydrodiol 1,2-epoxides of be…
1995
In previous work we established the rat liver oval cell line OC/CDE 22 in order to study in vitro mechanisms of liver cell transformation. We have now exposed OC/CDE 22 cells to each of the four optically active fjord region dihydrodiol epoxides of benzo[c]phenanthrene to investigate their capacity for malignant transformation of liver cells. All four configurational isomers, which are among the most potent carcinogenic metabolites of polycyclic aromatic hydrocarbons tested in murine tumour models, malignantly transform OC/CDE 22 cells at a 2 microM dose level, resulting in a similar colony-forming efficiency in soft agar. Inoculation of the transformed cells into newborn syngeneic rats pro…