ABSTRACT
Positively charged metallic oxides prevent blood coagulation whereas negatively charged metallic oxides are thrombogenic. This study was performed to examine whether this effect extends to metallic oxide nanoparticles. Oscillation shear rheometry was used to study the effect of zinc oxide and silicon dioxide nanoparticles on thrombus formation in human whole blood. Our data show that oscillation shear rheometry is a sensitive and robust technique to analyze thrombogenicity induced by nanoparticles. Blood without previous contact with nanoparticles had a clotting time (CT) of 16.7 ± 1.0 min reaching a maximal clot strength (CS) of 16 ± 14 Pa (G') after 30 min. ZnO nanoparticles (diameter 70 nm, +37 mV zeta-potential) at a concentration of 1 mg/mL prolonged CT to 20.8 ± 3.6 min and provoked a weak clot (CS 1.5 ± 1.0 Pa). However, at a lower concentration of 100 µg/mL the ZnO particles dramatically reduced CT to 6.0 ± 0.5 min and increased CS to 171 ± 63 Pa. This procoagulant effect decreased at lower concentrations reaching the detection limit at 10 ng/mL. SiO2 nanoparticles (diameter 232 nm, -28 mV zeta-potential) at high concentrations (1 mg/mL) reduced CT (2.1 ± 0.2 min) and stimulated CS (249 ± 59 Pa). Similar to ZnO particles, this procoagulant effect reached a detection limit at 10 ng/mL. Nanoparticles in high concentrations reproduce the surface charge effects on blood coagulation previously observed with large particles or solid metal oxides. However, nanoparticles with different surface charges equally well stimulate coagulation at lower concentrations. This stimulation may be an effect which is not directly related to the surface charge.
Subject(s)
Blood Coagulation , Nanoparticles/chemistry , Zinc Oxide/chemistry , HumansABSTRACT
BACKGROUND: Cell-based approaches towards restoration of prolapsed or degenerated intervertebral discs are hampered by a lack of measures for safe administration and placement of cell suspensions within a treated disc. In order to overcome these risks, a serum albumin-based hydrogel has been developed that polymerizes after injection and anchors the administered cell suspension within the tissue. METHODS: A hydrogel composed of chemically activated albumin crosslinked by polyethylene glycol spacers was produced. The visco-elastic gel properties were determined by rheological measurement. Human intervertebral disc cells were cultured in vitro and in vivo in the hydrogel and their phenotype was tested by reverse-transcriptase polymerase chain reaction. Matrix production and deposition was monitored by immuno-histology and by biochemical analysis of collagen and glycosaminoglycan deposition. Species specific in situ hybridization was performed to discriminate between cells of human and murine origin in xenotransplants. RESULTS: The reproducibility of the gel formation process could be demonstrated. The visco-elastic properties were not influenced by storage of gel components. In vitro and in vivo (subcutaneous implants in mice) evidence is presented for cellular differentiation and matrix deposition within the hydrogel for human intervertebral disc cells even for donor cells that have been expanded in primary monolayer culture, stored in liquid nitrogen and re-activated in secondary monolayer culture. Upon injection into the animals, gels formed spheres that lasted for the duration of the experiments (14 days). The expression of cartilage- and disc-specific mRNAs was maintained in hydrogels in vitro and in vivo, demonstrating the maintenance of a stable specific cellular phenotype, compared to monolayer cells. Significantly higher levels of hyaluronan synthase isozymes-2 and -3 mRNA suggest cell functionalities towards those needed for the support of the regeneration of the intervertebral disc. Moreover, mouse implanted hydrogels accumulated 5 times more glycosaminoglycans and 50 times more collagen than the in vitro cultured gels, the latter instead releasing equivalent quantities of glycosaminoglycans and collagen into the culture medium. Matrix deposition could be specified by immunohistology for collagen types I and II, and aggrecan and was found only in areas where predominantly cells of human origin were detected by species specific in situ hybridization. CONCLUSIONS: The data demonstrate that the hydrogels form stable implants capable to contain a specifically functional cell population within a physiological environment.
Subject(s)
Hydrogel, Polyethylene Glycol Dimethacrylate/pharmacology , Intervertebral Disc Degeneration/therapy , Intervertebral Disc/cytology , Rheology/drug effects , Adolescent , Adult , Animals , Biomarkers/metabolism , Cell Transplantation , Cells, Cultured , Cross-Linking Reagents/chemistry , Disease Models, Animal , Extracellular Matrix/metabolism , Female , Glycosaminoglycans/metabolism , Humans , Hydrogel, Polyethylene Glycol Dimethacrylate/chemistry , Intervertebral Disc/drug effects , Intervertebral Disc/metabolism , Male , Mice , Mice, SCID , Middle Aged , Phenotype , Regeneration , Reproducibility of Results , Serum Albumin/chemistry , Species Specificity , Treatment Outcome , Young AdultABSTRACT
We cultured isolated islets from human or porcine origin in the presence or absence of IL1 and TNFα and studied cytoprotective effects of two structurally different PBR ligands. Storage of pig or human islets in the presence of cytokines significantly lowered the fraction of vital beta-cells. Compared with cytokine incubations PK11195 alone or in combination with cytokines was effective to prevent cytokine induced cell death. The data indicate that cold storage in the presence of PK11195 may further protect beta-cells from cytokine induced cell death. This ligand may be helpful to preserve beta-cell survival before transplantation.
Subject(s)
Cytokines/pharmacology , Cytoprotection/drug effects , Insulin-Secreting Cells/cytology , Insulin-Secreting Cells/drug effects , Isoquinolines/metabolism , Isoquinolines/pharmacology , Receptors, GABA-A/metabolism , Animals , Cell Death/drug effects , Cell Survival/drug effects , Cold Temperature , Flow Cytometry , Humans , Insulin-Secreting Cells/transplantation , Islets of Langerhans Transplantation , Ligands , Substrate Specificity , Swine , Tissue PreservationABSTRACT
Evidence has been presented that mitochondria contain ATP sensitive potassium channels (mK-ATP channels), which may confer tissue protection upon activation. It is, however, not known whether activation of mK-ATP channels has a direct effect on mitochondrial ATP production. This study was performed to define the effect of pinacidil (PIN) on ATP production by oxidative phosphorylation in isolated cardiomyocyte or pancreatic beta-cell mitochondria. Cardiomyocyte mitochondria produced seven times more ATP than beta-cell mitochondria in the presence of pyruvate/malate. PIN inhibited pyruvate/malate-induced mitochondrial ATP production with half maximal effect at 360 microM in both cell types. The inclusion of 5-hydroxydecanoate (5-HD) did not prevent this inhibition. Succinate induced a similar ATP production in cardiomyocyte or beta-cell mitochondria. In beta-cell mitochondria succinate-induced ATP production was inhibited by PIN with half maximal effects at 500 microM PIN. However, in cardiomyocyte mitochondria PIN stimulated succinate-induced ATP production 3-fold with half maximal effect at 100 microM and maximal effect at 200 microM. This PIN-dependent stimulation was mimicked by rotenone. The inclusion of 5-HD could not prevent these PIN effects. In conclusion, PIN may inhibit complex 1 of the respiratory chain without indications of opening mK-ATP channels. In cardiomyocytes with metabolically inhibited succinate dehydrogenase this results in a stimulation of ATP production conferring tissue protection. In beta-cells without a metabolically inhibited succinate dehydrogenase, there is no stimulation by PIN and tissue protection by PIN is not to be expected.
Subject(s)
Adenosine Triphosphate/metabolism , Islets of Langerhans/drug effects , Membrane Proteins/metabolism , Mitochondria, Heart/drug effects , Myocardium/metabolism , Pinacidil/pharmacology , Adenylate Kinase/metabolism , Animals , Decanoic Acids/pharmacology , Drug Interactions , Female , Heart/drug effects , Hydroxy Acids/pharmacology , Islets of Langerhans/enzymology , Islets of Langerhans/metabolism , Membrane Proteins/drug effects , Mice , Mitochondria, Heart/enzymology , Mitochondria, Heart/metabolism , Myocardium/enzymology , Potassium Channels , Rotenone/pharmacology , Succinic Acid/pharmacology , Uncoupling Agents/pharmacology , Vasodilator Agents/pharmacologyABSTRACT
Reportamos un análisis de las 1624 defunciones ocurridas durante el año 1990 en la Clínica Infantil Dr. Robert Reid Cabral. Se evidencia como primer grupo de patologías responsables de defunción las enfemedades infecciosas, y en segundo lugar los accidentes. No hubo predilección por sexos. Más de dos terceras partes fueron durante el primer año de edad e igual proporción tuvieron una estadía hospitalaria menor de 48 horas. Otro dato destacable es que el 22 por ciento de los pacientes tenían una desnutrición de tercer grado asociada. No hubo predominio en las estaciones del año
Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Adolescent , Infant Mortality , Heart Defects, Congenital/epidemiology , Gastroenteritis/epidemiology , Infant, Premature , Pneumonia/epidemiology , Prospective Studies , Sepsis/epidemiologyABSTRACT
Se presenta el caso de un niño de 15 años de edad con enfermedad de Crohn. Es el primer caso reportado en la literatura médica nacional y el único documento por histopatología en los últimos 10 años en el Hospital Infantil Dr. Robert Reid Cabral
