Body fat content of seven lean women (body mass index (BMI) 20.6 (SD 1.8) kg/m2) and seven overweight women (BMI 31.1 (SD 3.3) kg/m2) was estimated by six different methods: underwater weighing (UWW), body-water dilution (BWD), whole-body counting ('@K), skinfold thickness (SFT), bioelectrical impedance (BEI) and magnetic resonance imaging (MRI). Using UWW as the reference method, the differences between percentage fat by each other method and the percentage fat by UWW were calculated for each subject. The mean difference was lowest for SFT and highest for BWD. MRI showed the lowest variability in individual results, and '@K the highest. "K and BWD methods used in combination gave better agreement with UWW results than either "K or BWD methods alone. There was a weak negative correlation between the difference from the UWW results and percentage fat in the SFT measurements, but not in the BWD, QK, BE1 or MRI measurements, suggesting that for these methods the assumptions involved produced no greater inaccuracy in the overweight women than in the lean women. In all subjects the BE1 offered little improvement over the traditional SFT measurements.The agreement between MRI and UWW estimates in both lean and overweight women suggests that MRI may be a satisfactory substitute for the more established methods of body fat estimation in adult women.
The effect of inorganic zinc on the absorption of inorganic iron (Fe+2) from a solution was assessed in two studies on healthy male volunteers. In the first study coadministration of 344 mumol of zinc had no effect (p less than 0.5) on the absorption of 842 mumol of radiolabeled Fe, assessed by the area under plasma Fe increment time curve during the 3 (AUC3) and 6 (AUC6) h postadministration (Fe alone AUC3 = 176.4 +/- 39.3; AUC6 = 387 +/- 101; Fe + Zn AUC3 = 180 +/- 33.1; AUC6 = 396 +/- 73.1 mumol.h-1.L-1), total plasma content of 59Fe, and whole-body retention of 59Fe. In the second study only the plasma appearance of Fe was monitored. After administration of 421 mumol of Fe alone, the AUC3 and AUC6 were 167 +/- 21.2 and 429.4 +/- 57 mumol.h-1.L-1, respectively; these were reduced to 56.4 +/- 17 and 119 +/- 34 (p less than 0.002) by 421 mumol Zn and further reduced by 1048 mumol Zn to 33 +/- 15 and 43.4 +/- 23.8 mumol.h-1.L-1 (p less than 0.001), respectively. It is concluded that Zn can impair the intestinal absorption of Fe.
The turnover of a radiolabeled (65Zn) pool of endogenous zinc was monitored by using a whole-body counter in eight patients with celiac disease (CD) and analyzed by using a two-compartment model. The biological half-life of the first compartment (1-3 wk postadministration) was similar in healthy volunteers (122 +/- 34 d, means +/- SD) and untreated patients (97 +/- 21 d). The second compartment in the patients (3-12 wk postadministration) was shorter (159 +/- 22.5 d. p less than 0.001) than were reference values (218 +/- 27 d) but increased (291 +/- 71 d) after the patients started gluten-free diets. The percentage absorption of 65Zn (9.25 kBq) from a test meal containing 31 mumol (2 mg) zinc was similar in untreated patients (30.0 +/- 13%) and healthy volunteers (32.5 +/- 12.4%). These data show that in mild untreated CD increased turnover and loss of endogenous zinc occurs whereas the absorption of zinc from a customary zinc intake may be normal. The pathophysiological basis of this loss was not investigated.
Two compounds, a zeolite, clinoptilolite, and a ferrocyanide, potassium hexacyanocobalt (II) ferrate (II), were found to be the most effective adsorbers of caesium in vitro. When used in vivo they significantly reduced the absorption of caesium by sheep fed contaminated herbage. These compounds did not alter the rate of excretion of pre-absorbed caesium, which varied with the time from cessation of contamination.
1. Peak 47Ca absorption and 7 day 47Ca retention were measured by a whole-body radioactivity counting technique in 10 haemodialysis patients before and after treatment with 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25-(OH)2D3]. 2. Before treatment all patients had low peak 47Ca absorption and 7 day 47Ca retention. 3. After treatment with 1,25-(OH)2D3 (0 . 25-l microgram/day for 4-12 months) peak 47Ca absorption and 7 day 47Ca retention returned to normal. 4. After treatment with 24,25-(OH)2D3 (2 microgram/day for 4-12 months) peak 47Ca absorption and 7 day 47Ca retention remained at pretreatment levels. 5. It is concluded that physiological doses of 24,25-(OH)2D3 have no effect on calcium absorption or retention in uraemic man.
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