A decrease in serum zinc can be caused by a real zinc deficiency but can also be caused by an apparent zinc deficiency, e.g. in inflammatory stress. The aim of this study was to evaluate the diagnostic power of serum alkaline phosphatase (AP) activity in the discrimi nation between pathophysiologic states of "real" and "apparent" zinc deficiency. A decrease in serum zinc was induced in growing and adult rats, by providing a diet low in zinc and by causing inflammatory stress. AP activity was determined using reagents low or enriched in zinc. Serum AP was decreased in zinc-deficient adult rats (P < 0.01). In zinc-deficient growing rats AP activity was not different from normal rats but AP activity decreased rapidly. In the same growing rats a significant difference was found in AP activities determined using buffers low and enriched in zinc (P < 0.001) between both groups of rats. After inducing inflammatory stress a decrease in AP activity (P < 0.01) and serum zinc (P < 0.001) was seen during the first few days. After the initial phase of inflammation AP activity normalized, serum zinc showed a rise which after correction for the decrease in serum albumin reached the level of the control rats. A difference in AP activity in buffers low and enriched in zinc was observed only during the first few days after induction of inflammatory stress (P < 0.001). Probably the method of measurement of the difference in (1996) [109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126][127] enzyme activity, using buffers low and enriched in zinc, can be used as an indication for zinc deficiency in situations with changing AP enzyme concentrations. AP activity is decreased during the initial phase of inflammatory stress due to a decrease in serum zinc.

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Dietary sodium restriction is used in the Neth erlands in the prophylaxis of preeclampsia. To study the effects of long-term sodium restriction on the intake of other nutrients and the outcome of pregnancy, 6 8 healthy nulliparous pregnant women were randomly assigned to either a low-sodium diet (20 mmol/24 h) or an unrestricted diet. The diet was consumed between week 14 of gestation and delivery. The dietary intakes of energy, fat, protein, carbohydrate, sodium, potassium, and calcium were esti mated with the dietary-history technique. A low-sodium diet re duced the intake of protein (by «=15 g/24 h), fat (by 20 g/24 h), and calcium (by 350 mg/24 h) and tended to decrease the energy intake (by ^O.? MJ/24 h). The intakes of carbohydrate and potassium did not differ between the groups. The maternal weight gain was less in the low-sodium group (6.0 ± 3 .7 compared with 11.7 ± 4.7 kg). Mean birth weight was not significantly different (3.2 ± 0.5 compared with 3.4 ± 0.5 kg).Am J Clin Nutv 1995;62:49-57.KEY WORDS Sodium-restricted diet, pregnancy, prophy laxis of preeclampsia, energy intake, fat intake, protein intake, carbohydrate intake, calcium intake, maternal weight gain, birth weight, body fat mass

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We compared the dual-precipitation method for measurement of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 (Gidez et al., J Lipid Res 1982;23:1206-33) with density-gradient ultracentrifugation in a swinging-bucket rotor (Demacker et al., Clin Chem 1983;29:656-63). The concentration of dextran sulfate 15,000 (DS) needed for optimal accuracy of the HDL2-chol and HDL3-chol values was established empirically. At a DS concentration of 0.87 g/L, the values for HDL2-chol as well as for HDL3-chol in 88 sera did not differ significantly from those obtained by ultracentrifugation. The precision of the method was satisfactory and was related to the concentration. Nevertheless, the dual-precipitation method lacks specificity inasmuch as it produces no fractions that contain only one HDL subfraction. HDL2 and HDL3 each contained an equivalent amount of cholesterol from the other. At increasing DS concentrations, some radiolabeled HDL3 appeared to have precipitated prior to complete precipitation of HDL2. This lack of specificity can be tolerated in large-scale epidemiological studies for screening, but not in small-scale intervention studies or in assay of clinical samples, where better accuracy is needed and ultracentrifugation is preferred.