Changes in dietary zinc and copper affect zinc-status indicators of postmenopausal women, notably, extracellular superoxide dismutase and amyloid precursor proteins

Metallothionein concentrations in erythrocyte lysates derived from human subjects were measured by an ELISA procedure. IgG obtained from serum of sheep injected with human metallothionein 1 was used in this competitive assay. Subjects were fed a semipurified zinc-deficient diet (0.7 mg of zinc per kg of diet) for an 8-day depletion period after 3 days of acclimation. Fasting plasma zinc concentrations were reduced approximately 7%. Metallothionein in the erythrocyte lysates was significantly decreased to 59% of the initial level by the end of the depletion period. Supplementation of these depleted subjects with zinc (50 mg) did not increase erythrocyte metallothionein levels within 24 hr. Daily supplementation of control subjects with zinc (50 mg/day) increased erythrocyte metallothionein to a 7-fold maximum within 7 days. These levels were reduced by 61% within 14 days after zinc supplementation was terminated. Incubation of rat [35S]metallothionein with human erythrocyte lysate showed a time-dependent increase in 35S soluble in 20% trichloroacetic acid, indicating degradation of the labeled protein, presumably via protease activity in the lysate. It is proposed that zinc supplementation induces erythrocyte metallothionein during erythropoiesis and that low zinc intake decreases synthesis and/or accelerates degradation of the protein in reticulocytes/erythrocytes. Metallothionein levels in erythrocytes may provide a useful index upon which to assess zinc status in humans.

Zinc

Zinc: An Essential Trace Element for Parenteral Nutrition

We have previously reported a trapping of zinc in the placenta directly related to circulating cadmium that comes from cigarette smoke. The purpose of this study was to examine in detail the effect of smoking on (a) the relationship between maternal and fetal zinc status and (b) the relationship between zinc status and birth weight. One hundred and eighteen smokers and 172 nonsmokers without any medical complications during pregnancy were studied. Atomic absorption spectroscopy was used to assess zinc status in maternal and cord vein plasma and red blood cells. Plasma alkaline phosphatase was also determined as an index of zinc status. Thiocyanate was used as an index of smoking status. The data were analyzed using univariate correlations and repeated measures analysis of variance. Infants of smokers had a statistically significant decrease in plasma zinc (5%), alkaline phosphatase (13%), and in cord vein RBC zinc (12%). Furthermore, the results showed an altered relationship between maternal and fetal indices of zinc status and zinc status and birth weight due to maternal smoking. The infant of the nonsmoking mother appears to be able to maintain adequate zinc status due to depletion of maternal zinc. However, it appears that the infant of the smoking mother may be marginally zinc deficient. These findings support studies of zinc supplementation in the pregnancy complicated by smoking.

The amyloid precursor protein (APP) and its proteolytic product amyloid beta (Abeta) are associated with both familial and sporadic forms of Alzheimer disease (AD). Aberrant expression and function of microRNAs has been observed in AD. Here, we show that in rat hippocampal neurons cultured in vitro, the down-regulation of Argonaute-2, a key component of the RNA-induced silencing complex, produced an increase in APP levels. Using site-directed mutagenesis, a microRNA responsive element (RE) for miR-101 was identified in the 3'-untranslated region (UTR) of APP. The inhibition of endogenous miR-101 increased APP levels, whereas lentiviral-mediated miR-101 overexpression significantly reduced APP and Abeta load in hippocampal neurons. In addition, miR-101 contributed to the regulation of APP in response to the proinflammatory cytokine interleukin-1beta (IL-lbeta). Thus, miR-101 is a negative regulator of APP expression and affects the accumulation of Abeta, suggesting a possible role for miR-101 in neuropathological conditions.

Competitive Reverse Transcriptase–Polymerase Chain Reaction Shows That Dietary Zinc Supplementation in Humans Increases Monocyte Metallothionein mRNA Levels1–3

Effect of consuming hi-oleic peanuts on adiposity and cardiometabolic health

The present study focused on whether serum extracellular superoxide dimutase (EC-SOD) activity can be used as a functional indicator of marginal zinc deficiency in humans. Subjects in this study were 444 healthy adults over 30 yr of age living a normal rural life in Kyunggi province, Korea. The mean dietary zinc intake of subjects obtained from one 24-h recall was 6.41 +/- 4.35 mg and the average serum zinc concentration of the subjects was 11.06 +/- 2.44 micromol/L. Subjects were divided into three groups by serum zinc concentrations: adequate (serum zinc >10.7 micromol/L), low (serum zinc 9.0-10.7 micromol/L), and very low (serum zinc <9.0 micromol/L) groups. A total of 50 subjects were selected from the three groups for analysis of EC-SOD activities. The EC-SOD activity of subjects increased with increasing serum zinc concentrations, and the activities of the three groups were significantly different as indicated by the Kruskal-Wallis test (p = 0.0239). Also, serum EC-SOD activities were significantly correlated with serum zinc concentrations (r = 0.289, p = 0.04). Serum EC-SOD activities, however, were not significantly correlated to the dietary zinc intakes. In conclusion, these results show that EC-SOD activities are decreased in subjects with low serum zinc concentrations and suggest that EC-SOD activity may be a functional indicator of zinc nutritional status in humans.

Red blood cell metallothionein as an indicator of zinc status during pregnancy

In order to study the reliability of urinary zinc levels as an index of zinc metabolism and status in Crohn's disease, we evaluated plasma and urinary zinc concentrations, urinary 3-methylhistidine excretion, and Crohn's disease activity index (CDAI) in 42 patients affected by Crohn's disease. Plasma zinc correlated directly with albuminemia (P = 0.01) and inversely with CDAI (P = 0.001). Urinary zinc excretion correlated with urinary 3-methylhistidine (P = 0.001) and plasma zinc levels (P = 0.01), and inversely with CDAI (P = 0.05). However, from multiple regression analysis, it was found that zincemia is influenced by CDAI and not by albumin, whereas zincuria is related to urinary 3-methylhistidine and plasma zinc, and not to CDAI. Our conclusion is that, in Crohn's disease, zincuria can be an index of zinc status when used together with measurements of lean body mass and turnover and factors influencing plasma ultrafiltrable zinc fraction.

Assessment of Marginal Zinc Status in Humans

Assessment of Zinc Status

Investigation of Lymphocyte Gene Expression for Use as Biomarkers for Zinc Status in Humans

Metallothionein Expression Is Increased in Monocytes and Erythrocytes of Young Men during Zinc Supplementation , ,

Low dietary zinc alters indices of copper function and status in postmenopausal women