ABSTRACT
This study evaluates the biological behaviour, in vitro and in vivo, of silicated hydroxyapatite with and without insulin adsorbed on the material surface. Insulin was successfully adsorbed on hydroxyapatite and silicated hydroxyapatite bioceramics. The modification of the protein secondary structure after the adsorption was investigated by means of infrared and circular dichroism spectroscopic methods. Both results were in agreement and indicated that the adsorption process was likely to change the secondary structure of the insulin from a majority of α-helix to a ß-sheet form. The biocompatibility of both materials, with and without adsorbed insulin on their surface, was demonstrated in vitro by indirect and direct assays. A good viability of the cells was found and no proliferation effect was observed regardless of the material composition and of the presence or absence of insulin. Dense granules of each material were implanted subcutaneously in mice for 1, 3 and 9 weeks. At 9 weeks of implantation, a higher inflammatory response was observed for silicated hydroxyapatite than for pure hydroxyapatite but no significant effect of adsorbed insulin was detected. Though the presence of silicon in hydroxyapatite did not improve the biological behaviour, the silicon substituted hydroxyapatite remained highly viable.
Subject(s)
Drug Implants , Durapatite/chemistry , Insulin/administration & dosage , Insulin/pharmacokinetics , Osteoblasts/drug effects , Silicates/chemistry , Adsorption , Animals , Cells, Cultured , Drug Carriers/chemistry , Drug Carriers/pharmacology , Drug Implants/chemistry , Durapatite/pharmacology , Female , Humans , Male , Materials Testing , Mice , Osteoblasts/physiology , Silicates/pharmacology , Subcutaneous AbsorptionABSTRACT
We examined the participation of MAPK and PKA in the Golgi complex disassembly caused by light-activated Calphostin C in HT-29 cells. When these cells were incubated with Calphostin C, fragmentation and dispersal of the Golgi complex was observed as assessed by immunofluorescence microscopy. Electron microscopy analysis showed that clusters of vesicles and large tubule-vesicular membrane structures, resembling the Golgi remnants present in mitotic cells, substituted the Golgi stacks. In addition, Calphostin C treatment caused inhibition of the endocytic route. We confirmed that the Golgi disassembly was not due to PKC inhibition, and suggested, based on the use of specific inhibitors, that other kinases are involved. It was shown that pretreatment with PD98059 and H-89, both inhibitors of MAPK and PKA, respectively, prior to incubation with Calphostin C, caused blockade of the Golgi disassembly, as well as the inhibition of the endocytic pathway caused by this drug. This finding supports the existence of a novel mechanism by which MAPK and PKA may regulate the Golgi breakdown caused by Calphostin C in HT-29 cells.
Subject(s)
Cyclic AMP-Dependent Protein Kinases/metabolism , Golgi Apparatus/metabolism , Golgi Apparatus/radiation effects , Light , Mitogen-Activated Protein Kinases/metabolism , Naphthalenes/pharmacology , Naphthalenes/radiation effects , Endocytosis/drug effects , Endocytosis/radiation effects , Flavonoids/pharmacology , Fluorescent Antibody Technique , Golgi Apparatus/drug effects , Golgi Apparatus/ultrastructure , HT29 Cells , Horseradish Peroxidase/metabolism , Humans , Isoquinolines/pharmacology , Naphthalenes/chemistry , Staurosporine/pharmacology , Sulfonamides/pharmacologyABSTRACT
It has been suggested that hypokinesia (diminished muscular activity)* may induce substantial changes in water metabolism in animal tissues. Thus, the objective of this study was to try to determine water metabolism reactions in 115 rats weighing 156-168 g under hypokinesia (HK) of 60-days and during the readaptation period (RP) of 15-days. All of the examined rats were divided into experimental and control groups. The experimental group of rats were subjected to pure HK, that is, without the use of any preventive measures, and the control group placed under ordinary vivarium conditions and served as control. For the simulation of the hypokinetic effect the experimental group of rats were kept in small individual cages made of plexiglas, which restricted their movements in all directions without hindering feed and water intake. Both groups of rats received water and salt supplements. Fluid intake and elimination, sodium and potassium content in urine and blood, hematocrit index and water content in blood were measured. Under hypokinesia a marked diuresis and electrolyte excretion as well as changes in blood electrolyte composition were demonstrated. Hematocritic index and blood water content changed unreliable. During the readaptation period diuresis and mineral excretion diminished substantially. It was concluded that exposure to hypokinesia induced significant changes in water metabolism of rats, regardless of the additional intake of water and salts.
