RESUMEN
The biochemical mechanism behind the strong binding between titanium and living bone has not been fully elucidated, in spite of worldwide clinical application of this phenomenon. We hypothesized that one of the core mechanisms may reside in the interaction between certain proteins in the host tissues and the implanted titanium. To verify the interaction between titanium and proteins, we chose the technique of chromatography in that titanium spherical beads (45 µm) were packed into a column to obtain a bed volume of 16×50 mm, which was eluted with phosphate buffered saline (PBS) and a straight gradient system made by using PBS and 25 mM NaOH. Fetal calf serum, albumin, lysozyme, casein, phosvitin and dentin phosphoprotein (phosphophoryn) were applied to the column. Most part of albumin and lysozyme eluted with the breakthrough peak, indicating practically no affinity to titanium. Fetal bovine serum also eluted mostly as the breakthrough peak, but distinct retained peak was observed. On the other hand, α-casein, phosvitin and phosphophoryn exhibited a distinct retained peak separated from the breakthrough peak. We proposed that phosphate groups (phosphoserines) in the major phosphoproteins, α-casein, phosvitin and phosphophoryn may be involved in the binding of these proteins with titanium.
Asunto(s)
Cromatografía/métodos , Fosfoproteínas/metabolismo , Titanio/metabolismo , Animales , Caseínas/sangre , Bovinos , Peso Molecular , Muramidasa/sangre , Fosfatos/metabolismo , Fosfoproteínas/análisis , Fosfoproteínas/sangre , Fosvitina/sangre , Unión Proteica , Albúmina Sérica/análisis , Titanio/análisisRESUMEN
1. Histologic and metabolic changes take place in livers of rooster receiving challenges consisting of acute doses of estrone. 2. During initial Growth and Redifferentiation livers rapidly increase in size by division of hepatocytes within most lobules, changing from cordlike to acinar configurations. 3. No new lobules appear and degeneration of some cells within lobules takes place even as cell divisions predominate. 4. Cells within lobules assume secretory features. 5. Vitellogenins, very low density lipoproteins, calcium and alkaline phosphatase increase greatly in plasma. 6. Within 35-40 days of cessation of estrogen, livers have returned to near normal sizes and plasmas exhibit normal parameters.
Asunto(s)
Estrona/toxicidad , Hígado/patología , Fosfatasa Alcalina/sangre , Animales , Apolipoproteínas/sangre , Diferenciación Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Pollos , Replicación del ADN/efectos de los fármacos , Hiperplasia , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Fosvitina/sangreRESUMEN
The title of this paper commemorating the contributions made by Professor Urist has an interesting bearing upon basic skeletal tissue biology. This is because the calcium-binding proteins (vitellogenins), upon which Professor Urist and Schjeide have focused much of their attention in non-mammalian vertebrates, although produced by the liver and present in the blood plasmas of non-mammalian vertebrates during vitellogenesis, are, in effect, substitutes for the protein casein present in the milk of mammalian vertebrates. Vitellogenins (180,000-250,000 daltons) appear to be produced solely for deposition in the yolk of the egg so that the calcium they carry (considerably more than is associated with casein of milk) and the amino acids of which they are comprised can be utilized during embryonic development. In many instances the progeny of non-mammalian vertebrates emerge from the shell as miniatures of the adult, capable of rapid movement and thus requiring a well developed skeletal as well as muscular system. Vitellogenins are not found in any other cells (phagocytes excepted) other than hepatocytes wherein they are made, nor are they present in the intercellular matrix of developing or remodeling bone. In non-vitellogenic females and in males of non-mammalian vertebrates, they are absent from the blood plasma altogether, so that nonionized calcium therein is solely bound to such proteins as albumin and the lipoproteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Calcio/metabolismo , Proteínas Dietéticas del Huevo , Anfibios/metabolismo , Animales , Transporte Biológico , Proteínas de Unión al Calcio/metabolismo , Diferenciación Celular , División Celular , Embrión de Pollo , Pollos , Proteínas del Huevo/análisis , Proteínas del Huevo/sangre , Proteínas del Huevo/metabolismo , Yema de Huevo/análisis , Estrógenos/farmacología , Peces/metabolismo , Humanos , Hígado/citología , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Fosvitina/análisis , Fosvitina/sangre , Fosvitina/metabolismo , Tiroxina/farmacología , Ultracentrifugación , Vitelogénesis , Vitelogeninas/análisis , Vitelogeninas/biosíntesis , Vitelogeninas/metabolismoRESUMEN
The distribution of plasma iron between transferrin-iron (Tf-Fe) and phosvitin-iron (Phv-Fe) over a 98 week laying period was established in hens. Six plasma samples were collected at random from a group of 20 pullets, starting when the birds were 20 weeks old. Samples were collected weekly until the 29th week and subsequently on the 41st, 62nd, and 98th weeks. Detailed assays were carried out to differentiate Phv-Fe from Tf-Fe. Phosphoprotein (phosvitin) concentrations were also determined. At the beginning of sexual activity, (23 to 24 weeks) females showed a parallel increase of Tf-Fe and Phv-Fe. During the period of maximum egg production 29 to 41 weeks) Tf-Fe was 65% and the Phv-Fe 35% of the total plasma iron. During this period the transferrin saturation reached a maximum of 80%; both transport mechanisms worked simultaneously. Estrogen administration to male chickens (2 injections of 5 mg/kg body weight) precipitated similar variation patterns of the two plasma irons over a period of 7 days. It is suggested that the estrogens were responsible for these variations.