Erythrocytes, erythrocyte membranes, neutrophils and platelets as biopsy materials for the assessment of zinc status in humans.

The influence of laser light (670 nm) on human erythrocyte membrane Na+,K(+)-ATPase activity in the presence and absence of Zn-phthalocyanine (ZnPc) was studied. The response of erythrocyte membranes to low-power laser irradiation has not been fully elucidated. In our study, we focused on the studies on photo-induced changes of Na+,K(+)-ATPase activity. The erythrocyte membrane suspensions were incubated with 2 mM of ZnPc and next irradiated with energy doses of 19.1, 38.2, 57.3, 76.4, and 95.5 J x cm(-2). The activity of Na+,K(+)-ATPase was assayed colorimetrically at the wavelength of 820 nm and expressed in micromol of inorganic phosphate released from ATP per mg of protein. The measurements of Na+,K(+)-ATPase activity in erythrocyte membranes incubated with ZnPc in the dark demonstrated that all concentrations of the dye (0.5, 1, 2, and 3 microM) stimulated enzyme activity. The concentration of 2 microM caused the smallest increase of enzyme activity, so this concentration was accepted for further studies. Irradiation of erythrocyte membranes in the presence of the dye (2 microM) significantly decreased Na+,K(+)-ATPase activity. Only for energy doses of 19.1 and 38.2 J x cm(-2) was the enzyme activity comparable to the activity of the control. It was found that irradiation with all energy doses applied caused a rise of enzyme activity. In the presence of ZnPc, significant decrease of Na+,K(+)-ATPase activity was observed.

A longitudinal assessment of maternal zinc status in normal pregnant women

Effect of zinc source and dietary level on zinc metabolism in Holstein calves.

The aim of this study was to determine the concentrations of nickel and cadmium in blood plasma of the people exposed to cement dust emissions and to investigate the effects of exposure period on the activities of Na+/K+ ATPase enzymes in their erythrocyte membranes. The study was carried out on people living in Eskişehir Cukurhisar rural area, located near a cement factory. Blood samples of the individuals residing in this area were taken from 80 subjects (30 for control) following a physical examination. The analysis of plasma samples showed that nickel concentrations in subject group were found to be significantly higher than those of the control group (p < 0.001). Cadmium concentrations were found to be within the reference values for both group and no difference was found between the subjects and controls (p > 0.05). Furthermore, no correlation was observed between the levels of Na+/K+ ATPase activity in erythrocyte membranes of the subject group and the ages of people living in the region (p > 0.05, r = 0.133). It was also observed that nickel concentrations increased by age (p < 0.001, r = 0.646) while no effect was observed in means of cadmium. Na+/K+ ATPase activities in the erythrocyte membranes were not affected. In conclusion although there was no difference between the Na+/K+ ATPase activity in means of age, there was an environmental pollution and may be it was due to the industrial plant.

Lipid composition and Na+,K+-ATPase activity in erythrocyte membranes of patients with type 2 diabetes mellitusand dyslipoproteinemia

Reduced acetylcholinesterase activity in erythrocyte membranes from patients with phenylketonuria

The DRI assumes FZA to be constant when estimating dietary Zn needs, regardless of Zn intake or status. We assessed the independent effects of Zn intake and status on FZA in adult men. Nine men (aged 28–50 yrs, BMI 21–26, usual dietary Zn intake >11 mg/d) were studied 3 times: 1) at baseline; 2) after 1 wk on a liquid diet of 0.6 mg Zn/d and 5 wks on a low Zn diet (LoZ, 4 mg Zn/d); and 3) after 4 wks on an adequate zinc diet (AdZ, 11 mg Zn/d) with supplemental Zn (20 mg/d) given for the first 7d. At the end of each period, subjects consumed a day of 3 AdZ test meals with oral tracers of 67Zn (total 1.1 mg 67Zn/d) followed by a day of 3 LoZ test meals with oral tracers of 70Zn (total 0.4 mg 70Zn/d) or vice versa, depending on diet period. Five days after oral dosing, 0.5 mg 70Zn was given IV. Urine collected d 3–5 and d 8–10 after oral dosing was analyzed by ICPMS for 67:66 and 70:66 Zn ratios. FZA was estimated using a modified dual isotope tracer ratio method. Mean FZA was greater from LoZ meals than from AdZ meals (61 ± 14 % vs 36 ± 9 %, p<0.0001), regardless of diet period. Mean combined FZA of test meals decreased from the LoZ to the final AdZ period (53 ± 20 % vs 44 8 ± 16 %, p= 0.04). Plasma Zn concentration did not change by diet period. In summary, current Zn intake markedly affects FZA and is independent of smaller changes in FZA due to chronic zinc intake. Supported by NCBA and GCRC at SFGH, NCRR, NIH (grant MO1-RR00083-43).

Calcium-ATPase activity (Mg2+-dependent Ca2+-ATPase, ATP phosphohydrolase, EC 3.6.1.3) in erythrocyte membrane preparations from cystic fibrosis (CF) patients was greatly reduced compared to erythrocyte membranes from control subjects. The Km for calcium was found to be similar in the two groups; however, the Vmax, the maximal rate of activation of the Ca2+-ATPase, is reduced by 50% in the erythrocyte membrane preparations of the CF patients (P less than 0.001). In contrast, the Mg2+-ATPase activity of erythrocyte membranes from CF patients was unchanged compared to the control subjects. No difference in the Na+,K+-ATPase activity in erythrocyte membranes from CF patients compared to control patients could be observed. This indicates that the Ca2+-ATPase activity noted in CF erythrocytes is not part of a generalized membrane or membrane-bound enzyme alteration. It remains to be determined whether this alteration in Ca2+-ATPase activity is directly related to a defect in calcium transport in these cells and is a generalized phenomenon in CF present in cell types more directly involved in secretion.

Simple SummaryLittle is known about the effects of animal- and diet-related factors on the plasma zinc (Zn) concentrations of horses and ponies. Additionally, it is unclear if plasma samples are adequate to reflect changes in the Zn intake. In the first part of the study, the impact of age, sex, horse type (ponies vs. horses), and internal diseases on the plasma Zn concentrations was evaluated in 538 patients of an Equine Clinic. The second part was a feeding study with two healthy horses and eight healthy ponies to assess the effects of two dietary Zn supplements on the plasma and mane hair Zn concentrations of the animals. Part 1: The age, sex, and horse type did not influence the plasma Zn concentrations. No effect of internal diseases was observed, with the exception of higher plasma Zn concentrations in animals with metabolic diseases compared to the control group. Part 2: Both Zn supplements increased the Zn concentrations in the mane hair, but not in the plasma, in a dose-dependent manner. In conclusion, the plasma Zn concentrations were widely unaffected by nutritional and non-nutritional factors in horses and ponies, while mane hair samples better reflected the Zn supply with the diet.Little is known about the animal- and diet-related factors that could interfere with the plasma zinc (Zn) concentrations of equines. Additionally, the adequacy of plasma to reflect changes in the Zn intake is unclear. In the first part of this study, the plasma Zn concentrations of hospitalized horses and ponies (n = 538) were measured and evaluated for the impact of the age, sex, horse type, and internal diseases of the animals. In the second part, the effects of increasing dietary Zn chloride hydroxide and Zn methionine supplementations were assessed on the plasma and mane hair Zn concentrations of healthy horses (n = 2) and ponies (n = 8). Part 1: The age, sex, and horse type did not influence the plasma Zn concentrations. No effect of internal diseases was observed, with the exception of higher plasma Zn concentrations in animals with metabolic disorders compared to the control group (p < 0.05). Part 2: Both Zn supplements dose-dependently increased the Zn concentrations in the mane hair (p = 0.003), but not in the plasma of the horses and ponies. In conclusion, the plasma Zn concentrations were widely unaffected by nutritional and non-nutritional factors in equines, while mane hair samples better reflected the dietary Zn supply.

Na(+), K(+)-ATPase activity was determined in erythrocyte membranes from 12 phenylketonuric patients of both sexes, aged 8.8 +/- 5.0 y, with plasma phenylalanine levels of 0.64 +/- 0.31 mM. The in vitro effects of phenylalanine and alanine on the enzyme activity in erythrocyte membranes from healthy individuals were also investigated. We observed that Na(+), K(+)-ATPase activity was decreased by 31% in erythrocytes from phenylketonuric patients compared with normal age-matched individuals (p < 0.01). We also observed a significant negative correlation between erythrocyte Na(+), K(+)-ATPase activity and plasma phenylalanine levels (r = -0.65; p < 0.05). All PKU patients with plasma phenylalanine levels higher than 0.3 mM had erythrocyte Na(+), K(+)-ATPase activity below the normal range. Phenylalanine inhibited in vitro erythrocyte Na(+), K(+)-ATPase activity by 22 to 34%, whereas alanine had no effect on this activity. However, when combined with phenylalanine, alanine prevented Na(+) K(+)-ATPase inhibition. Considering that reduction of Na(+), K(+)-ATPase activity occurs in various neurodegenerative disorders leading to neuronal loss, our previous observations showing a significant reduction of Na(+), K(+)-ATPase activity in brain cortex of rats subjected to experimental phenylketonuria and the present results, it is proposed that determination of Na(+), K(+)-ATPase activity in erythrocytes may be a useful peripheral marker for the neurotoxic effect of phenylalanine in phenylketonuria.

The identification of an enzyme activity that responds to changes in Zn intake may serve as a useful biomarker for Zn status. Alkaline phosphatase (ALP) is a dimeric protein with each subunit containing two Zn atoms. The activity of ALP in erythrocytes (E) decreases as a result of a low Zn diet, which suggests that this enzyme may be a marker of Zn status. To investigate this further, we determined the response of E-ALP in six healthy subjects following supplementation with 50 mg Zn (4.2 x RDI) daily for 4 wk. A small but significant increase in plasma Zn was observed with supplementation (p < 0.05), whereas there was no significant change in E-Zn over the same period. Plasma and E-Cu showed no change. Conversely, the activity of E-ALP increased in all subjects from 1.7 +/- 0.5 to 5.9 +/- 0.7 U/g protein (mean +/- SE) (p < 0.0001). The small change observed in plasma Zn is not biologically significant in view of the many documented factors that influence its concentration. Our data support the hypothesis that E-ALP is a marker of Zn status in humans.

Background: ill health may lead to poor nutrition and poor nutrition to ill health, so identifying priorities for management still remains a challenge. The aim of this report is to present data on the impact of plasma zinc (Zn) depletion on important health outcomes after adjusting for other poor prognostic indicators in hospitalised patients. Hospitalised acutely ill older patients who were part of a large randomised controlled trial had their nutritional status assessed using anthropometric, hematological and biochemical data. Plasma Zn concentrations were measured at baseline, 6 weeks and at 6 months using inductively- coupled plasma spectroscopy method. Other clinical outcome measures of health were also measured. A total of 345 patients assessed at baseline, 133 at 6 weeks and 163 at 6 months. At baseline 254 (74%) patients had a plasma Zn concentration below 10.71 μmol/L indicating biochemical depletion. The figures at 6 weeks and 6 months were 86 (65%) and 114 (70%) patients respectively. After adjusting for age, co-morbidity, nutritional status and tissue inflammation measured using CRP, only muscle mass and serum albumin showed significant and independent effects on plasma Zn concentrations. The risk of non-elective readmission in the 6-months follow up period was significantly lower in patients with normal Zn concentrations compared with those diagnosed with Zn depletion (adjusted hazard ratio 0.62 (95% CI: 0.38 to 0.99), p = 0.047. Zn depletion is common and associated with increased risk of readmission in acutely-ill older patients, however, the influence of underlying comorbidity on these results can not excluded.

Bioavailability of zinc from zinc sulfate and different organic zinc sources and their effects on ruminal volatile fatty acid proportions

The aim of this study was to evaluate the substrate (ATP) kinetics of erythrocyte membrane Na, K-ATPase in children with borderline or essential hypertension. Although the activity of Na, K-ATPase in the presence of in vivo concentrations of ATP was not significantly altered, kinetic studies showed an obvious inhibition of enzyme activity in the erythrocyte membrane of children with borderline or essential hypertension. Hanes plot analysis revealed a decrease of V(max) from 7.19 in erythrocytes from control subjects to 4.93 and 3.33 in those from children with borderline or essential hypertension, respectively. A mean value of the K(m) decreased from 0.10 in the control to 0.08 and 0.02 in children with borderline or essential hypertension, respectively. The energy status of erythrocytes, estimated by ATP, ADP and AMP levels, ATP/ADP ratio, and adenylate energy charge (AEC) was not significantly changed in the cells from hypertensive children. The use of a free radical-generating system (FeSO4/ascorbate) in vitro significantly reduced enzyme activity in the control erythrocytes while in those from hypertensive children it was abolished completely. The level of lipid peroxides was considerably higher (+ 37 per cent) in the plasma, while that of reduced glutathione was significantly lower both in the erythrocytes and the plasma of children with essential hypertension than in healthy children. These results indicate significant alterations of the antioxidant status which could be the cause of the inhibited Na, K-ATPase activity in erythrocyte membranes from hypertensive children.

Decreased Na,K-ATPase Activity in Erythrocyte Membranes and Intact Erythrocytes from Obese Man