Three-year study on trace mineral concentration in the blood plasma of Shetland pony mares

Changes in some trace minerals concentrations (calcium, inorganic phosphorus, magnesium, zinc, iron, copper, sodium and potassium) in blood plasma were investigated during a three-year period in Shetland pony mares. Blood plasma mineral concentrations were determined by the atomic absorption method and colorimetric method. The three-year averages were in micrograms/ml; Na 4630 +/- 168; K 277 +/- 3.8; Ca 171 +/- 3.8; P 31.5 +/- 0.74; Fe 1.92 +/- 0.14; Zn 1.07 +/- 0.04 and Cu 1.06 +/- 0.02. Two trace minerals (magnesium in inorganic phosphorus) showed only long-term tendency changes--upward or downward trends were not connected with the season. Most of the investigated minerals showed both a long-term change tendency and more or less marked seasonally related concentration changes, being higher during autumn or winter (zinc, sodium), or during spring and summer (calcium, copper, iron and potassium). Some interrelationships between particular trace mineral concentrations in blood plasma were also observed.     

Zinc uptake across the apical membrane of freshwater rainbow trout intestine is mediated by high affinity,low affinity,and histidine-facilitated pathways

Zinc is both a vital nutrient and an important toxicant to aquatic biota. In order to understand the interplay between nutrition and toxicity, it will be important to determine the mechanisms and the factors that regulate zinc uptake. The mechanism of apical intestinal Zn(II) uptake in freshwater rainbow trout and its potential modification by the complexing amino acid histidine was investigated using brush-border membrane vesicles (BBMVs). Following characterisation of the BBMV preparation, zinc uptake in the absence of histidine was both time- and concentration-dependent and consisted of two components. A saturable phase of uptake was described by an affinity constant of 57+/-17 microM and a transport capacity of 1867+/-296 nmol mg membrane protein(-1) min(-1). At higher zinc levels (>500 microM) a linear, diffusive component of uptake was evident. Zinc transport was also temperature-dependent, with Q10 values suggesting zinc uptake was a carrier-mediated process. Zinc uptake by vesicles in the presence of histidine was correlated to a mono-histidine species (Zn(His)+) at all Zn(II) concentrations examined.     

Minerals leached into drinking water from rubber stoppers.

Drinking water and its delivery system are potential sources of variation in animal research. Concern arose that rubber stoppers used to cork water bottles might be a source of some nutritionally required minerals which could leach into drinking water. Six types of stoppers, each having different compositions, were cleaned with stainless-steel sipper tubes inserted into them and attached to polypropylene bottles filled with either deionized water (pH 4.5) or acidified-deionized water (pH 2.5). After six days of contact, water levels of copper, magnesium, iron, manganese, zinc, chromium, and selenium were determined by atomic absorption spectroscopy. Additionally, three of the stopper types were analyzed for mineral content. Minerals were present in both stoppers and drinking water. Acidified-deionized water generally leached minerals from the stoppers than did deionized water. The black stopper which is commonly used in animal facilities contained and leached measurable levels of some minerals, but it still can be recommended for typical animal husbandry uses, although other types of stoppers would be more suitable for specific nutritional and toxicologic studies.     

Determination of cadmium in blood, plasma, and urine by electrothermal atomic absorption spectrophotometry after isolation by anion-exchange chromatography

The determination of cadmium in whole blood, urine, or plasma by atomic absorption using electrothermal atomization is described. In preparation for atomic absorption analysis, cadmium was concentrated on an anion-exchange column, significantly lowering the limit of detection and allowing for the first time the accurate and precise determination of plasma cadmium concentrations in persons/animals with low-level cadmium exposures. Recovery of 109Cd from spiked whole blood, plasma, and urine into supernatants of nitric acid-deproteinated samples averaged 99, 100, and 95%, respectively. Anion-exchange isolation of the anionic chlorocadmium complex removed 99.8% of the major elements associated with a deproteinated whole blood sample. The recovery of 109Cd from the anion-exchange column was 92.2 +/- 0.9% (mean +/- SE, N = 35). The separation of cadmium from constituents in blood, urine, or plasma in this manner allowed comparison of unknown samples to aqueous standards with a defined acid matrix using commercially available acids. The mean intra-assay coefficient of variation (CV) was 12 +/- 3% (mean +/- SE, N = 6) for blood, plasma, and urine samples having cadmium concentrations of 0.1-0.8 microgram/liter. The interassay CV was 13% (N = 7) for a blood sample containing 0.6 microgram Cd/liter. The recovery of known amounts of cadmium added to blood, plasma, and urine in the range of 0.2 to 5.0 micrograms Cd/liter was 97 +/- 6% (mean +/- SE, N = 4).     

Zinc uptake by human placental microvillous membrane vesicles

Zinc uptake by syncytiotrophoblast microvillous membrane vesicles (SMMV) from human placentas was characterized and the effects of maternal serum zinc levels at term and of gestational age on kinetic parameters were evaluated. Zinc uptake at pH 7.2 was rapid for the first 2 min, followed by a slower increase, approaching equilibrium after 30 min. Uptake was saturable at a zinc concentration of 30 micromol/L, higher than the upper range of the physiological serum zinc level. Kinetic analysis of uptake at 1 min in SMMV from term placenta showed similar Km values (mean: 6.9+/-0.6 micromol/L) for different levels of maternal serum zinc. However, Vmax was higher (p < 0.05) in SMMV from mothers with serum zinc lower than 7.6 micromol/L compared to those with higher serum zinc levels (35.8+/-1.6 and 26.6+/-1.6 nmol 65Zn/mg protein/min, respectively). Km values were similar in term (>37 wk of gestation) and preterm (20-25 wk of gestation) placentas, whereas Vmax was higher (p < 0.05) in the preterm (34.3+/-1.6 nmol Zn/mg protein/min) compared to term placentas from mothers with serum zinc levels above 7.6 micromol/L. These results suggest that whereas afffinity for zinc was not altered with gestational age or maternal serum zinc levels, zinc-uptake capacity in human placenta is influenced both by gestational age and by low levels of maternal serum zinc in order to ensure an adequate maternal-fetal zinc transfer.     

Erythrocytary zinc and the infant growth profile in northeast Brazil

This study evaluated nutritional status linked to zinc levels in 239 randomly selected children at crèches in Teresina, Brazil, aged 3 to 6. Blood samples were collected after fasting of 10 h. Erythrocytary zinc levels were determined through flame atomic absorption spectrophotometry. Zinc deficiency was determined as below 40 microg Zn/g Hb. Infant linear growth was evaluated measuring weight and height, and nutritional status by height/age, weight/height, and weight/age indices, expressed as Z scores, in line with the National Center for Health Statistics. The mean zinc concentration was 35.50 +/- 10.95 microg Zn/g Hb. Zinc distribution in the 10, 50, 75, and 90 percentiles was 24.73 microg Zn/g Hb, 35.45 microg Zn/g Hb, 40.73 microg Zn/g Hb and 52.77 microg Zn/g Hb, respectively. Based on this distribution, normal values were found only from the 75th percentile and above. Since the cutoff point adopted was 40 microg Zn/g Hb, the prevalence of zinc deficiency was 74.3%. As for growth profile, 8.4% were chronically malnourished, although the statistical association between linear impairment and nutritional status regarding zinc was insignificant. The study revealed that an important segment of the infant population was mineral deficient; however, the degree of deficiency did not influence growth profiles.     

65Zn Uptake from Blood into Brain in the Rat

Zinc is essential for the normal development and function of the CNS, although little is known about brain zinc homeostasis. Therefore, in this investigation we have studied 65Zn uptake by brain from blood and have measured the blood-brain barrier permeability to 65Zn in the anaesthetised rat in vivo. Adult male Wistar rats within the weight range 500-600 g were used. 65ZnCl2 and 125I-albumin, the latter serving as a vascular marker, were injected intravenously in a bolus of normal saline. Sequential arterial blood samples were taken during experiments that lasted between 5 min and 5 h, after which the whole brain was removed, dissected, and analysed for radioisotope activity. Data have been analysed by graphical analysis, which suggests that after 30 min of circulation, 65Zn uptake by brain from blood is unidirectional with an influx rate constant, Kin, of approximately 5 X 10(-4) ml/min/g. At circulation times of less than 30 min, 65Zn fluxes between blood and brain are bidirectional, where influx has a K value of greater than 5 X 10(-4) ml/min/g. In addition to the blood space, the brain appears to contain a rapidly exchanging compartment(s) for 65Zn of approximately 4 ml/100 g, which is not CSF.     

Bioavailability of zinc and its binding to casein in milks and formulas

Differences in zinc bioavailability among milk and formulas may be attributed to binding of zinc to various ligands. We determined the distribution of zinc and protein at different pHs and zinc and calcium concentrations. We used radiolabelled cow's milk, human milk, whey-predominant (WPF) and casein-predominant (CPF) infant formula. Lowering the pH changed zinc and protein distribution: zinc shifted from pellet (casein) to whey in cow's milk, from fat to whey in human milk and from fat and pellet to whey in formulas. Protein shifted from whey to pellet in human milk and from whey and pellet to fat in formulas. Increasing zinc and calcium concentrations shifted protein and zinc from pellet to whey for cow's milk and from whey and pellet to fat for the formulas. Protein distribution was not affected by calcium or zinc addition in human milk or CPF, while zinc shifted from whey to fat in human milk and from fat and pellet to whey in CPF. Zinc and calcium binding to isolated bovine or human casein increased with pH. At 500 mg/L of zinc, bovine casein bound 32.0 +/- 1.8 and human casein 10.0 +/- 0.9 mg zinc/g protein. At 500 mg/L of calcium, calcium was preferentially bound over zinc. Adding calcium and zinc resulted in 32.0 +/- 1.8 mg zinc/g bound to bovine casein and 17.0 +/- 0.8 mg zinc/g to human casein, while calcium binding was low. Suckling rat pups dosed with 65Zn labelled infant diets were killed and individual tissues were gamma counted. Lower zinc bioavailability was found for bovine milk at pH = 4.0 (%65Zn in liver = 18.7+1.4) when compared to WPF (22.8 +/- 1.6) or human milk (26.9 +/- 0.8). Lowering the pH further decreased zinc bioavailability from human milk, but not from cow's milk or WPF. Knowledge of the compounds binding minerals and trace elements in infant formulas is essential for optimizing zinc bioavailability.     

Influence of low dietary calcium during pregnancy and lactation on zinc levels in maternal blood and bone in rats.

The effect of low dietary calcium on maternal zinc nutritional status was studied. Two groups of 6 adult female Wistar rats were fed during pregnancy and lactation with experimental diets containing either 0.2 g (LCa) or 0.6 g (NCa) of calcium/100 g. Both diets contained/100 g: 20.0 g protein (potassium caseinate), 3.5 mg Zn, 0.6 g P. A third group (n = 6) was fed a "stock diet" (SG), containing/100 g: 24.8 g protein, 1.5 g Ca, 0.6 g P, 11.6 mg Zn. Maternal blood samples were drawn from the tail before mating (To), at delivery (D) and at weaning (W); dams were sacrificed at weaning and the right femur was excised. Determinations (atomic absorption spectrometry) were: Zinc in red blood cells (RBC), Zn and Ca in ashed femur. The results (mean +/- SD) were: RBCZn (microg/mL) at To: 8.65 +/- 1.80, which did not change in the SG or in the NCa groups, but increased significantly in the LCa group (p < 0.001) (D: 18.20 +/- 4.63; W: 26.70 +/- 6.02), regarding To. Femur Zn (microg/100 mg) showed an increase (p < 0.001) in the LCa group (30.2 +/- 2.1) regarding both SG (25.3 +/- 0.7) and NCa groups (24.1 +/- 0.7). Femur Ca (mg/100 mg) decreased (p < 0.05) in the LCa group (19.2 +/- 0.9) regarding both SG (24.0 +/- 0.5) and NCa groups (21.4 +/- 0.7) and leading to a significant increase in Zn/Ca ratio (p < 0.001) in the LCa group. Therefore, dietary calcium deficiency during pregnancy and lactation would produce an increase of Zn utilization, reflected in the increase of maternal blood Zn levels and in femur Zn content.     

Zinc and copper of fetal organs during the second trimester of pregnancy

In fetus with a mean gestational age of 18 weeks (range 15-25, n = 14), zinc and copper concentrations in liver, femur, rib, and skeletal muscle were measured. Zinc and copper concentrations are highest in liver. A trend of decreasing liver zinc concentrations during gestational age is suggested. Zinc concentrations are significantly correlated with copper concentrations in liver and in femur, suggesting steady growth in both organs. Femur zinc values rank ca. 30% of those in liver, femur copper, ca. 2%. Zinc or copper concentrations in rib are of the same levels as in skeletal muscle. Their concentration for zinc ranks ca. 20%, for copper, ca. 5% of the values in liver. All zinc and copper values are lower than reported in third trimester fetal organs. Calculated zinc/copper molar ratios are distinctive for the various organs: in liver, 6 +/- 1, in femur, 73 +/- 8, and in soft tissues, 26 +/- 3. Calculated ratios from published values obtained from the third trimester of pregnancy show that the ratios in liver and skeletal muscle maintain these levels. The zinc/copper molar ratio can serve as an internal reference in zinc and/or copper measurements.     

Indices of iron and copper status during experimentally induced,marginal zinc deficiency in humans

This study examined the effect of diet-induced, marginal zinc deficiency for 7 wks in 15 men (aged 25.3 +/- 3.3 yrs; mean +/- SD) on selected indices of iron and copper status. The regimen involved low-zinc diets based on egg albumin and soy protein with added phytate and calcium such that mean [phytate]/[Zn] and [phytate] X [Ca]/[Zn] molar ratios were 209 and 4116, respectively, for 1 wk, followed by 70 and 2000, respectively, for 6 wks. Subjects were then repleted with 30 mg Zn/d for 2 wks. Plasma copper, Cu,Zn-superoxide dismutase (Cu,Zn-SOD) activity in plasma and red blood cells (RBC), hemoglobin, hematocrit, and serum ferritin were determined weekly on fasting blood samples. Significant reductions (p less than 0.05) after 7 wks in RBC Cu,Zn-superoxide dismutase (49.5 +/- 7.2 vs 33.6 +/- 6.3 U/mg Hb) and serum ferritin (69.2 +/- 38.7 vs 53.8 +/- 33.7 micrograms/L) occurred; no comparable decline was noted for plasma Cu, hemoglobin, or hematocrit. Significant (p less than 0.05) but less consistent changes were also observed in plasma superoxide dismutase activity. None of the changes were associated with the decreases in plasma, urinary and hair zinc concentrations, and alkaline phosphatase activity in RBC membranes. Results indicate that the biochemical iron and copper status of the subjects was marginally impaired, probably from the dietary regimen that induced marginal zinc deficiency.     

Evidence for a zinc/proton antiporter in rat brain

The data presented in this paper are consistent with the existence of a plasma membrane zinc/proton antiport activity in rat brain. Experiments were performed using purified plasma membrane vesicles isolated from whole rat brain. Incubating vesicles in the presence of various concentrations of 65Zn2+ resulted in a rapid accumulation of 65Zn2+. Hill plot analysis demonstrated a lack of cooperativity in zinc activation of 65Zn2+ uptake. Zinc uptake was inhibited in the presence of 1 mM Ni2+, Cd2+, or CO2+. Calcium (1 mM) was less effective at inhibiting 65Zn2+ uptake and Mg2+ and Mn2+ had no effect. The initial rate of vesicular 65Zn2+ uptake was inhibited by increasing extravesicular H+ concentration. Vesicles preloaded with 65Zn2+ could be induced to release 65Zn2+ by increasing extravesicular H+ or addition of 1 mM nonradioactive Zn2+. Hill plot analysis showed a lack of cooperativity in H+ activation of 65Zn2+ release. Based on the Hill analyses, the stoichiometry of transport may include Zn2+/Zn2+ exchange and Zn2+/H+ antiport, the latter being potentially electrogenic. Zinc/proton antiport may be an important mode of zinc uptake into neurons and contribute to the reuptake of zinc to replenish presynaptic vesicle stores after stimulation.     

Influence of the glass packing on the contamination of pharmaceutical products by aluminium. Part III: Interaction container-chemicals during the heating for sterilisation

The interaction of chemicals with the container materials during heating for sterilisation was investigated, storing the components of parenteral nutrition solutions individually in sealed glass ampoules and in contact with a rubber stopper, and heating the system at 121 degrees C for 30 min. Subsequently, the aluminium content of the solutions was measured by atomic absorption spectrometry (AAS). The assay was also carried out with acids, alkalis and some complexing agents for Al. The containers were decomposed and also assayed for aluminium. 30 different commercial solutions for parenteral nutrition, stored either in glass or in plastic containers, were assayed measuring the aluminium present in the solutions and in the container materials. The results of all investigated container materials revealed an aluminium content of 1.57% Al in glass, 0.05% in plastic and 4.54% in rubber. The sterilisation procedure showed that even pure water was able to extract Al from glass and rubber, 22.5 +/- 13.3 microg/L and 79.4 +/- 22.7 microg/L respectively, while from plastic the aluminium leached was insignificant. The Al released from glass ampoules laid between 20 microg/L for leucine, ornithine and lysine solutions and 1500 microg/L for solutions of basic phosphates and bicarbonate; from rubber stoppers it reached levels over 500 microg/L for cysteine, aspartic acid, glutamic acid and cystine solutions. Ion-exchange properties and influence of pH can explain the interaction of glass with some chemicals (salts, acids and alkalis), but only an affinity for aluminium could explain the action of some amino acids and other chemicals, as albumin and heparin, on glass and rubber, considering the aluminium release. Experiments with complexing agents for Al allowed to conclude that the higher the stability constant of the complex, the higher the Al release from the container material.     

Zinc-induced decrease of the thermal stability and regeneration of rhodopsin

Zinc is present at high concentrations in the photoreceptor cells of the retina where it has been proposed to play a role in the visual phototransduction process. In order to obtain more information about this role, the study of the effect of zinc on several properties of the visual photoreceptor rhodopsin has been investigated. A specific effect of Zn(2+) on the thermal stability of rhodopsin, obtained from bovine retinas and solubilized in dodecyl maltoside detergent, in the dark is reported. The thermal stability of rhodopsin in its ground state (dark state) is clearly reduced with increasing Zn(2+) concentrations (0-50 microm Zn(2+)). The thermal bleaching process is accelerated in the presence of Zn(2+) with k rate constants, at 55 degrees C, of 0.028 +/- 0.002 min(-1) (0 microm Zn(2+)) and 0.056 +/- 0.003 min(-1) (50 microm Zn(2+)), corresponding to t(12) values of 24.4 +/- 1.6 min and 11.8 +/- 0.1 min, respectively. Thermodynamic parameters derived from Arrhenius plots show a significant E(a) increase at 50 microm Zn(2+) for the process, with deltaG++ decrease and increase in deltaH++ and deltaS++ possibly reflecting conformational rearrangements and reordering of water molecules. The stability of the metarhodopsin II intermediate is also decreased and changes in the metarhodopsin II decay pathway are also detected. The extent of rhodopsin regeneration in vitro is also reduced by zinc. These effects, specific for zinc, are also seen for rhodopsin in native disc membranes, and may be relevant to the suggested role of Zn(2+) in normal and pathological retinal function.     

Effect of blood handling on extracellular Hsp72 concentration after high-intensity exercise in humans

Heat shock protein 72 (Hsp72) has been detected in the peripheral circulation of humans. Because intracellular Hsp72 binds to aggregated proteins, we hypothesized that postexercise plasma-derived Hsp72 concentrations would be greater than serum-derived Hsp72 because of binding of Hsp72 to aggregated clotting proteins in serum. Postexercise serum, heparin, and ethylenediaminetetraacetic acid (EDTA) samples were collected from 9 recreationally active males and were analyzed for Hsp72 by enzyme-linked immunosorbent assay. In line with our hypothesis, EDTA-treated blood was significantly higher in Hsp72 concentration than all other treatments (P < or = 0.001), whilst heparin plasma (LH) was significantly higher than serum derived on ice (SI) and at room temperature (SR) (P < 0.05; EDTA: 6.46 +/- 0.76, LH: 2.73 +/- 2.26, SI: 0.13 +/- 0.24, SR: 0.20 +/- 0.32 ng/mL). Because previous research has tended to report serum data at the lowest point of the detectable range of the assay, it is recommended that EDTA specimen tubes be used in future investigations.     

Iodine and zinc, but not selenium and copper, deficiency exists in a male Turkish population with endemic goiter

Although endemic goiter has been shown to have a high prevalence in Turkey, little is known about the concentration of urinary iodine, plasma selenium (Se), copper (Cu), and zinc (Zn) in these patients. We studied on 140 male patient with endemic goiter (mean age: 22.2 ± 0.19 yr) and 140 healthy male subjects (mean age: 21.8 ± 0.28 yr). Daily urinary iodine excretion was determined by the ionometric method. Plasma Se, Zn, and Cu were determined by using atomic absorption spectrometry. Daily urinary iodine excretion was found to be significantly lower in the patient group (38.7 ± 2.26 μg/d) than that of controls (50.73 ± 2.56 μg/day,p = 0.001). Plasma Zn concentrations were also found to be significantly lower in the patient group (1.04 ± 0.03 μg/mL) than that of controls (1.16 ± 0.02 μg/mL,p = 0.001). No significant difference was determined in Se and Cu concentrations between the patient and control groups. Our study shows that a moderate iodine deficiency exists in both patients with endemic goiter and control subjects, which indicates the important role of iodine deficiency in the etiopathogenesis of endemic goiter in Turkey. Zinc deficiency may also contribute to the pathogenesis of endemic goiter. However, Se and Cu do not seem to have any role in the etiopathogenesis of endemic goiter in Turkey. A community-based iodine fortification program throughout the country may be proposed to take over the problem, which also can prevent the contributing effects of other element deficiencies that occur when iodine deficiency is the prevailing factor.     

Selenium, zinc, and copper concentrations in the blood and milk of lactating women

The aim of the study was to determine Se, Zn, and Cu concentrations in blood plasma and milk of lactating women from central Poland who were in different stages of lactation and to investigate the relationship between the content of trace elements in mothers’ blood and concentrations of microelements in their milk. Se and Zn concentrations in blood plasma of mothers were the lowest and Cu was the highest on the first 4 d of lactation (colostrum, n=43) and were found to be 34.9±11.8 μg/L, 0.51±0.13 mg/L, and 1.70±0.55 mg/L, respectively. The highest plasma level of Se and Zn and the lowest content of Cu could be observed between d 10 and 30 of lactation (mature milk, n=41), and were found to be 54.3±14.6 μg/L for Se (p<0.001), 0.76±0.20 mg/L for Zn (p<0.001), and 1.03±0.30 mg/L (p<0.001) for Cu. The results of Se, Zn, and Cu determination in breast milk samples demonstrate a pattern of decline in their concentration with advancing stages of lactation. We found out that Se, Zn, and Cu concentrations were the highest in colostrum (n=43) and amounted to 24.8±10.1 μg/L, 8.2±2.8 mg/L, and 0.45±0.11 mg/L, respectively. The content of all determined microelements declined significantly during the time of lactation. Statistically significant linear correlation was found between concentrations of Zn in blood plasma and milk in the first stage of lactation. Weak but statistically significant linear correlations were also found between plasma Se content in plasma and in transitional and mature milk of breast-feeding women.     

Development of new insulinomimetic zinc(II) picolinate complexes with a Zn(N2O2) coordination mode: structure characterization, in vitro, and in vivo studies

Three zinc(II) complexes of picolinic acid and its derivatives with a Zn(N2O2) coordination mode were prepared and evaluated for their insulinomimetic activities by in vitro and in vivo studies. By introducing an electron-donating methyl group into the picolinate ligand (pic), bis(6- or 3-methylpicolinato)zinc(II) complexes [Zn(6-mpa)2 or Zn(3-mpa)2, respectively] were prepared. The Zn(6-mpa)(2) complex was crystallized as a water adduct [Zn(6-mpa)2(H2O)].H2O, in which two carboxylate oxygens and two pyridine nitrogens of 6-mpa and a water oxygen coordinate to a zinc(II) with a trigonal bipyramidal geometry. By in vitro evaluation of the inhibition of free fatty acid (FFA) release from isolated rat adipocytes in the presence of epinephrine, the insulinomimetic activities of Zn(pic)2, Zn(6-mpa)2, and Zn(3-mpa)2 (IC50=0.64 +/- 0.13, 0.31 +/- 0.05, and 0.40 +/- 0.07 mM, respectively) were found to be higher than those of VOSO(4) (IC50=1.00 mM) and ZnSO(4) (IC50=1.58 +/- 0.05 mM) in terms of IC50 value, the 50% inhibition concentrations for the FFA release from the adipocytes. Then, Zn(6-mpa)2, which exhibited the highest in vitro insulinomimetic activity among three complexes examined, was given at a dose of 3.0 mg (45.9 micromol) Zn/kg body weight to KK-A(y) mice with type 2 diabetes mellitus by daily intraperitoneal injections for 14 days and it was found that the hereditary high blood glucose levels were lowered during the administration of the complex. The improvement of diabetes mellitus was confirmed with the oral glucose tolerance test.     

Studies on zinc bioavailability from a representative diet in Chinese urban women of childbearing age using a double label stable isotope technique

The objectives of the study were to determine dietary zinc bioavailability by using a double label stable isotope technique, and to identify the zinc content and levels of some possible factors which may affect zinc utilization in a typical representative Chinese urban diet. Twenty urban women of childbearing age were fed a diet extrinsically labeled with 67Zn and received intravenous (i.v.) injections of 70Zn. Fecal monitoring, urine monitoring and chemical balance technique were used simultaneously for comparisons. Isotopic enrichment in feces and urine after oral and i.v. administration of stable zinc isotopes was measured to determine the ways of zinc absorption. The mean (+/-SD) zinc intake from the representative Chinese diet was 10.22+/-0.80 mg/day, which is lower than the reference nutrient intake (RNI) level (11.5 mg/day), and mainly came from the subsidiary foods (63%). The mean dietary Fe/Zn weight was 1.1+/-0.1. The phytate/zinc molar ratio in the diet was about 3:1. The phytic acidxCa/zinc molar ratio in the diet was about 45:1. The apparent and true absorption rates of 67Zn were 36.2+/-9.7% and 38.2+/-10.1%, respectively, which were higher than the apparent absorption determined by balance technique (29.7+/-10.6%). The mean fractional absorption (FA) determined in urine was 35.7+/-13.3. In conclusion, the subsidiary food is the main source of dietary zinc in this typical diet. The extrinsic labeling technique by use of stable isotopes was more reliable and accurate to determine zinc absorption. Moreover, the double isotopic tracer ratio (DITR) technique applied to urine samples was a more practical and valuable way to evaluate zinc absorption than other methods. It can be speculated that iron and phytic acid might not be the main inhibitors in the representative Chinese diet.     

Surma and lead poisoning.

Blood lead concentrations were measured in 62 Asian children, of whom 37 had definitely had surma applied to their eyes and 25 were thought not to have done. The mean concentration in those who had not used surma was 0.98 +/- SD 0.42 mumol/1 (20.3 +/- 8.7 microgram/100 ml) compared with 1.65 +/- 0.68 mumol/4 (34.2 +/- 14.1 microgram/100 ml) in those who had. Analysis of 29 different samples of surma showed 23 of them to be composed largely of lead sulphide. We conclude that the use of surma is associated with high blood lead concentrations. In our cases most of it had been obtained abroad, and hence government restrictions might be ineffective in limiting its use: a better method of prevention might be to inform the leaders of Asian communities of the risks.