Biomedical subjects

A Givan

Publications and source records attributed to A Givan.

2 recordsLinked to original sources

PubMed1999

La ions in precipitated hydroxyapatites.

Hydroxyapatites were synthesized by precipitation from an aqueous solution with La3+ (0-0.75%) and with carbonate (0-6.1%) at controlled pH 7.0. Uptake of La3+ was 90-95% complete. Relatively low Ca/P (1.54-1.63) ratios were attributed to nonstoichiometry. Carbonate in samples was identified by IR spectroscopy as B-type carbonate. Lattice parameters of the hexagonal apatite structure were not affected by the La3+ content. Noncarbonated samples heated to 800 degrees C transform partially to beta-Ca3(PO4)2. Thermogravimetric analysis showed release of 0.4 mol adsorbed and 1 mol crystalline water up to 400 degrees C and decomposition of carbonate up to 900 degrees C in the samples. Luminescence data obtained for Gd-containing hydroxyapatites prove that Gd3+ ions are not incorporated in the precipitated hydroxyapatite. These findings suggest that, in the La-containing samples, La3+ is surface absorbed and not incorporated in hydroxyapatite.

Calcium↗

PubMed1990

Blood transfusion and surgery: the effect on growth of a syngeneic sarcoma.

The effects of blood transfusion, blood components, and surgical trauma on the growth of an experimental sarcoma have been examined. Recipient animals were inbred adult female WAB rats, which received allogeneic transfusions from inbred adult female PVG rats, syngeneic blood from inbred colony-mates, or saline infusions. Small volume transfusions (1-4 ml) of whole blood had no effect on tumour growth, but growth of the MC7 sarcoma was significantly enhanced following allogeneic transfusions of 5 ml whole blood, or when 4 ml was combined with sham laparotomy. Maximal enhancement of tumour growth occurred when 4 ml transfusions of allogeneic washed cells were given, but allogeneic plasma was also able, to a lesser degree, to enhance tumour growth. These data confirm that blood transfusion may enhance growth of the MC7 sarcoma, that the effect may be dose dependent, and synergistic with the immunosuppression of surgery. Many components of an allogeneic transfusion may be responsible for this effect.

Animals↗