ABSTRACT
The influence of extra cellular matrix on the biochemical activity of hepatocytes was studied by maintaining rat hepatocytes in primary culture in a serum free medium on different matrix protein substrata or biomatrices prepared from liver, aorta or mammary gland. There was significant difference in the individual protein synthesis and distribution by cells maintained on different substrata. Comparison of the kinetics of synthesis and secretion of albumin by cells maintained on different tissue biomatrix showed that those maintained on hepatic biomatrix synthesized more albumin and retained more of albumin synthetic capacity, when compared to those maintained on aortic and mammary gland biomatrix. Similarly, hepatocytes maintained on hepatic biomatrix synthesized significantly more apo B, the major apo protein of VLDL, than those maintained on heterologous tissue matrix. Induction of tyrosine aminotransferase by dexamethasone and the uptake of [14C]-amino isobutyric acid were found to be maximum in cells maintained on liver biomatrix than the heterologous biomatrix. But cells maintained on hepatic biomatrix incorporated less amounts of radioactivity into total cytoskeletal proteins as well as the individual proteins such as actin and the cytokeratins C8 and C18 while that by cells maintained on aortic biomatrix was significantly high. Quantitative analysis of the relative incorporation of radioactivity into individual cytoskeletal proteins and albumin in pulse labelling studies with cells maintained in culture on different matrix for different lengths of time revealed a reciprocal relationship between these two activities. These results indicate that the substrata with which the cells are in contact influence on a selective basis, the biochemical activity of hepatocytes in primary culture.
Subject(s)
Albumins/biosynthesis , Amino Acids/metabolism , Animals , Apolipoproteins B/biosynthesis , Asialoglycoproteins/metabolism , Cells, Cultured , Cytoskeletal Proteins/biosynthesis , Dexamethasone/pharmacology , Extracellular Matrix/metabolism , Liver/cytology , Rats , Tyrosine Transaminase/metabolismABSTRACT
Se estudió el efecto de la preparación in vitro de semen sobre la estructura y sobrevida del espermatozoide humano, con el objeto de valuar si la albúmina protege las membranas durante la centrifugación. Se analizaron de manera cegada y aleatoria 12 muestras seminales de hombres fértiles a las cuales se les trató por tres métodos diferentes (swim-up, gradientes de albúmina, gradientes de percoll), para separar la fracción móvil de espermatozoides. Las membranas plasmática y acrosomal externa y la sustancia acrosomal de los espermatozoides fueron observadas al microscopio electrónico de transmisión en 50 espermatozoides por muestra y la viabilidad y movilidad progresiva se analizó después de incubación durante 24 horas a 37ºC. Se presenta evidencia que sugiere que la albúmina estabiliza la membrana acrosomal externa del espermatozoide humano e incrementa la viabilidad de esta célula