O check changing in the systematic bias. The calibration curve was obtained using four iron absorption standard solutions (Sigma-Aldrich) in the range 0.2?.05 /ml. Tissue iron was also measured by the BPS-based colorimetric method and by DAB (methanol 3,3 diaminobenzidine) enhanced Perls’ stain, as previously reported [17].Fe and 57Fe-heme absorptionFor 57Fe absorption analyses, the stable iron isotope 57Fe (57Fe at 94 enrichment; Frontier Scientific Inc., Logan, Utah USA) was used as tracer. A 0.4 mol/L solution of 57FeSO4 has been prepared by 298690-60-5 biological activity overnight dissolution of 22.85 g 57Fe/L in 0.4 mol/L H2SO4 (Sigma Aldrich, Milano, Italy). The obtained 57FeSO4 solution was stored at 4 . Before its use, 87.7 mg sucrose and 0.83 mg ascorbic acid per mg iron were added to the 57FeSO4 solution to yield to a final concentration of 57Fe of 20 mmol/L, ascorbic acid of 5.38 mmol/L and sucrose of 10 , respectively. As negative control, an analogous solution without tracer was prepared. Both the 57FeSO4-labelled and the control solution were adjusted to pH=7 by adding the required volume of 1 mol/L NaOH. For 57Fe-heme absorption analyses, 10mg of 57Fe(III) Protoporphyrin IX chloride (Frontier Scientific Inc., Logan, Utah USA) were dissolved in the required volume of DMSO 100 to yield a final concentration of 20 mmol/L. The obtained solution was stored at 4 . To assess the in vivo absorption of 57FeSO4 or 57Fe-heme, 20 of 57FeSO4-labelled solution (correspondent to 22.8 57Fe) or 20 of 57Fe-heme labelled solution (correspondent to 22.8 57Fe contained in 260.8 57Fe-heme) were orally administered to overnight fasted mice. Control mice received vehicle solution. During the experiment mice received water ad lib. Tissues were collected at different times after the administration. Control mice represented the “0” time point of the experiment. The amount of 57Fe retained by the tissue upon the administration of 57FeSO4-labelled or 57Fe-heme labelled solutions was determined by inductively coupled plasma mass spectrometry (ICP-MS) and expressed as g of 57Fe per g of wet tissue, taking into account the amount of naturally occurring 57Fe. The percentage natural abundance of 57Fe in tissues of wildtype and Hx-null animals was checked before 57Fe and 57Feheme absorption analyses, resulting 23148522 comparable in the two groups (Figure S1). Further details on the experimental procedure are reported in [18].were prepared by homogenization in hypotonic buffer (10 mmol/L Tris-HCl buffer pH 7.4, 2 mmol/L MgCl2) with protease inhibitors (aprotinin, leupeptin, pepstatin; Cocktail Tablets, Roche Diagnostics). After 15 minutes incubation on ice, samples were sonicated and the homogenates were then adjusted to 0.25 mol/L sucrose. After centrifugation for 10 minutes at 1000g, the supernatant was removed and centrifuged for an additional 15 minutes at 12000g before being ultracentrifuged at 33000 rpm for 1 hour. The supernatant was discarded and the microsomal pellet was used for HO activity measurement. The enzyme reaction method was used in a 200 mixture (prepared in potassium phosphate buffer 100 mmol/L, pH 7.4, 2mmol/L MgCl2) containing 150 microsomal proteins, 25 ol/L hemin, 1 mmol/L NADPH, 2 mmol/L glucose-6-phosphate (G6P), 0.5 U G6P dehydrogenase, and 1 mg of rat liver cytosol proteins (33000 rpm supernatant) as a source of biliverdin reductase. Rat liver supernatant was prepared fresh by homogenization in 0.1 mol/L sodium HIF-2��-IN-1 biological activity citrate buffer, pH 5, containing 10 g.O check changing in the systematic bias. The calibration curve was obtained using four iron absorption standard solutions (Sigma-Aldrich) in the range 0.2?.05 /ml. Tissue iron was also measured by the BPS-based colorimetric method and by DAB (methanol 3,3 diaminobenzidine) enhanced Perls’ stain, as previously reported [17].Fe and 57Fe-heme absorptionFor 57Fe absorption analyses, the stable iron isotope 57Fe (57Fe at 94 enrichment; Frontier Scientific Inc., Logan, Utah USA) was used as tracer. A 0.4 mol/L solution of 57FeSO4 has been prepared by overnight dissolution of 22.85 g 57Fe/L in 0.4 mol/L H2SO4 (Sigma Aldrich, Milano, Italy). The obtained 57FeSO4 solution was stored at 4 . Before its use, 87.7 mg sucrose and 0.83 mg ascorbic acid per mg iron were added to the 57FeSO4 solution to yield to a final concentration of 57Fe of 20 mmol/L, ascorbic acid of 5.38 mmol/L and sucrose of 10 , respectively. As negative control, an analogous solution without tracer was prepared. Both the 57FeSO4-labelled and the control solution were adjusted to pH=7 by adding the required volume of 1 mol/L NaOH. For 57Fe-heme absorption analyses, 10mg of 57Fe(III) Protoporphyrin IX chloride (Frontier Scientific Inc., Logan, Utah USA) were dissolved in the required volume of DMSO 100 to yield a final concentration of 20 mmol/L. The obtained solution was stored at 4 . To assess the in vivo absorption of 57FeSO4 or 57Fe-heme, 20 of 57FeSO4-labelled solution (correspondent to 22.8 57Fe) or 20 of 57Fe-heme labelled solution (correspondent to 22.8 57Fe contained in 260.8 57Fe-heme) were orally administered to overnight fasted mice. Control mice received vehicle solution. During the experiment mice received water ad lib. Tissues were collected at different times after the administration. Control mice represented the “0” time point of the experiment. The amount of 57Fe retained by the tissue upon the administration of 57FeSO4-labelled or 57Fe-heme labelled solutions was determined by inductively coupled plasma mass spectrometry (ICP-MS) and expressed as g of 57Fe per g of wet tissue, taking into account the amount of naturally occurring 57Fe. The percentage natural abundance of 57Fe in tissues of wildtype and Hx-null animals was checked before 57Fe and 57Feheme absorption analyses, resulting 23148522 comparable in the two groups (Figure S1). Further details on the experimental procedure are reported in [18].were prepared by homogenization in hypotonic buffer (10 mmol/L Tris-HCl buffer pH 7.4, 2 mmol/L MgCl2) with protease inhibitors (aprotinin, leupeptin, pepstatin; Cocktail Tablets, Roche Diagnostics). After 15 minutes incubation on ice, samples were sonicated and the homogenates were then adjusted to 0.25 mol/L sucrose. After centrifugation for 10 minutes at 1000g, the supernatant was removed and centrifuged for an additional 15 minutes at 12000g before being ultracentrifuged at 33000 rpm for 1 hour. The supernatant was discarded and the microsomal pellet was used for HO activity measurement. The enzyme reaction method was used in a 200 mixture (prepared in potassium phosphate buffer 100 mmol/L, pH 7.4, 2mmol/L MgCl2) containing 150 microsomal proteins, 25 ol/L hemin, 1 mmol/L NADPH, 2 mmol/L glucose-6-phosphate (G6P), 0.5 U G6P dehydrogenase, and 1 mg of rat liver cytosol proteins (33000 rpm supernatant) as a source of biliverdin reductase. Rat liver supernatant was prepared fresh by homogenization in 0.1 mol/L sodium citrate buffer, pH 5, containing 10 g.
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