Reduction In Zinc Content Research Articles

A Zinc Uptake Transporter ZIP1-II Is Involved in Zinc Accumulation in the Hepatopancreas of Pacific Oyster Crassostrea gigas.

The Pacific oyster Crassostrea gigas is known to have an exceptional ability to accumulate zinc, which endows it with robust resistance to pathogens and makes it an excellent source of dietary zinc. ZIP1 has been identified as an important zinc uptake protein in other species, but its role in oysters remains unclear. In the present study, a ZIP1 homologue (CgZIP1-II) of the Zrt/Irt-like protein (ZIP) family was identified in C. gigas. The mRNA transcripts of CgZIP1-II were constitutively expressed in examined tissues of C. gigas, with higher levels in the hepatopancreas and gill. After zinc exposure, the mRNA transcripts of CgZIP1-II in the hepatopancreas showed a significant decline from 12 h to 14 d, while those in the gill significantly decreased at 72 h, followed by a recovery to basal level at 7 to 14 d. Immunocytochemical analysis revealed that the CgZIP1-II protein was mainly located at the plasma membrane of oyster hemocytes. Compared to the control cells, overexpression of CgZIP1-II in the transfected HEK293 cells resulted in a 2.44-fold (p < 0.05) increase in zinc content after incubation with 100 μM zinc for 24 h. Inhibition of endogenous CgZIP1-II expression with siRNAs led to a 42% reduction in zinc content in the hepatopancreas of oysters. Similarly, in vivo blocking of CgZIP1-II with anti-CgZIP1-II antibody caused a 43% decrease in zinc content in the hepatopancreas. These results collectively indicated that CgZIP1-II functioned as a zinc uptake transporter in C. gigas and played a certain role in zinc accumulation.

Kinetics of Zinc Evaporation from Aluminium Alloys Melted Using VIM and ISM Technologies.

Using a vacuum during the smelting and refining of alloys removes dissolved gasses, as well as impurities with high vapour pressure. When smelting is carried out in vacuum induction furnaces, the intensification of the discussed processes is achieved by intensive mixing of the bath, as well as an enhanced mass exchange surface (liquid metal surface) due to the formation of a meniscus. This is due to the electromagnetic field applied to the liquid metal. This study reports the removal of zinc from the Al-Zn alloy containing 6.3 wt.%. Zn. The experiments were carried out with the use of two types of metallurgical devices: the VIM and ISM furnaces. For the experiments carried out in the crucible induction furnace, reduction in the operating pressure in the furnace from 1000 Pa to 10 Pa, together with the increase in temperature from 953 K to 1103 K, is accompanied by a decrease in zinc content in the alloy from 6 to 96%, compared with the initial value. Simultaneously, the overall mass transfer coefficient kZn increases from 5.15 × 10−6 to −1.49 × 10−4 ms−1. For the experiments carried out in the furnace with a cold crucible (T = 953 K), a reduction in the operating pressure in the furnace from 1000 Pa to 10 Pa resulted in a decrease in zinc content in the alloy from 18 to 80%, compared with the initial value. For comparison, the experiments carried out in the crucible induction furnace at 953 K showed a reduction in zinc content in the alloy from 6 to 50%, which means that more intense zinc evaporation is seen in the furnace with a cold crucible. Comparison of ISM and VIM technologies in the removal efficiency of the Al-Zn alloy indicates a higher removal efficiency using the first technology, which, using the same conditions, achieves 80% of the removal efficiency of the component.

Sugar cane as an alternative green activator to conventional vulcanization additives in natural rubber compounds: Thermal degradation study

It is essential to deeply understand the chemical changes caused in the rubber compositions when using green additives, especially in the thermal degradation and stability. So, the objective of this research is the evaluation of the thermal degradation behavior of a typical natural rubber (NR) compound modified by silanized activator derived from sugar cane (green additive). The activator was used in order to replace the conventional zinc oxide and stearic acid additives commonly used as vulcanization activators. Different contents (1, 3, 5, 7 and 10 phr) were used in the NR compounds and the thermal stability was evaluated. It was observed that, according to the degradation proceeds, the weight loss tended to be similar at low temperatures for all the studied compounds, i.e., the reinforcement effect of the green additive was more pronounced at higher temperatures. However, the activation energy values significantly increased by using up to 3 phr of the sugar cane activator. Compared to the Control sample, this result suggested that the solid-state degradation mechanism appeared to change when the activator from sugar cane was added in the samples. In addition, the morphology showed that silanization treatment acted positively on the additive dispersion within NR matrix. In this scenario, the favorable results obtained, as well as the considerable reduction of zinc content (81%) used in the compositions, highlighted the possibility of changing the conventional activators such as zinc oxide and stearic acid by a green option from sugar cane.

Activator from sugar cane as a green alternative to conventional vulcanization additives

Activators are essential additives in the production of industrially viable elastomeric compounds. However, zinc oxide, the most widely used along with stearic acid, produces environmental damage due to tire wear; as a consequence, the powdered compound is released into the environment. For this reason, there is an intense search for additives from renewable sources that are sustainable, cheaper and eco-friendly. This work brings about the use of a new material from sugar cane as an alternative activator in the vulcanization of natural rubber. Both the favorable results obtained and the considerable reduction of zinc content (74.4%) used in the compounds, with similar results compared to the standard sample, highlight the possibility of changing conventional activators such as zinc oxide to a green option from sugar cane.

Alkaline Leaching of Low Zinc Content Iron-Bearing Sludges

Various types of waste materials containing zinc (e.g. dusts and sludges from gas dedusting process) are obtained in steel industry. The contents of Zn in these materials may vary considerably. Even a low concentration of zinc in recirculated products precludes their recycling in ferrous metallurgy aggregates. Long storage of this type of material can lead to contamination of soil and water by zinc compounds which can be leached out by acid rain, for example. This paper focuses on research involving alkaline leaching tests of low zinc content iron-bearing materials. These tests were preceded by the analysis of the elemental, phase and grain size composition, and analysis of the thermodynamic conditions of the leaching process. The main aim of research was to decrease the content of the zinc in the sludge to the level where it is suitable as an iron-bearing material for iron production (~1% Zn). Leaching at elevated temperatures (368 K, 60 min) has led to a decrease in the zinc content in the sludge of about 66%. The research revealed that long hour leaching (298 K, 100 hours) carried out at ambient temperatures caused a reduction in zinc content by 60% to the value of 1.15-1.2% Zn.

Development of passenger tire treads: reduction in zinc content and utilization of a bio-based lubricant

The present study aimed to characterize and determine the technical viability of using vegetable oil as a lubricant and vulcanization activator with low zinc content in a natural rubber tire tread as additives. These additives were used to replace traditionally used components in the rubber industry. The chemical and thermal characterizations of each alternative additive were performed using thermogravimetric analysis, Fourier transform infrared spectroscopy, and atomic absorption spectrometry. Nine samples were prepared with various vegetable oil contents (3, 4, 6, and 8 parts per hundred of rubber – phr) and vulcanization activators with lower zinc content (2, 3, 4, and 5 phr). The compositions were characterized using rheometry and physico-mechanical analyses. The obtained results were compared to the standard formulation of tire treads using naphthenic oil and zinc oxide. The thermal and chemical characteristics suggest that the vegetable oil has the typical structure of a phenol. The low-zinc-content vulcanization activator has the typical structure of an aromatic zinc carboxylate. The physico-mechanical properties of the samples indicate that the best performance was achieved with 3 phr of the low-zinc-content vulcanization activator and 3 phr of vegetable oil, which reduced the lubricant content by 50% and zinc content by 75% without unfavorably affecting the properties of the final product.

Translocation of trace elements in the system "Mother-placenta-fetus" in rats with physiological pregnancy and under conditions of lead exposure.

Heavy metals are the second major environmental pollutants. Especially toxic is lead, increased content of which in the body of a pregnant determines the development of pregnancy, childbirth and postpartum period complications and is potentiated by deficiency of essential trace elements - zinc and copper. Article presents the results of impact of solutions of lead acetate and citrate in experimental models. Solutions of metals were injected into the stomach through a tube once a day during 19 days of pregnancy in the dose of 0,05 mg/kg in the form of inorganic compound - lead acetate and in organic form – lead citrate. The content of trace elements - lead, cadmium, copper and zinc were determined by stripping voltamperometry. In addition, indices of placental and fetal accumulation, as well as index of transplacental migration were calculated. Effect of lead during pregnancy in all biosubstrates is increased by 1,3-1,9 times as compared with the control group. This causes imbalance of essential trace elements due to significant reduction in zinc content in all the studied biological substrates. Prolonged contact with lead during pregnancy leads to disruption of placenta, inability of the placenta to fully protect the fetus from excessive intranatal influence of xenobiotics.

Моделювання деяких біохімічних механізмів розвитку марганцевого гіпермікроелементозу

The aim of this work was to study the mechanisms of action of sub-toxic dose (LD50) of the manganese chloride on cell metabolism in rats’ organs and tissues under model conditions. A model of assessment of integral response of an organism to exogenous manganese at exposure levels close to the threshold that was realized as the repeated impact of sub-toxic doses. White Wistar rats aged 3 months were injected intramuscularly with MnCl2 with the metal concentration of 50 mg/kg for 8 days. Effect of exogenous manganese load on the content of macro- and microelements, such as Ca, Mg, Mn, Cu, Zn, and Pb, was studied in liver, heart, spleen, kidneys, muscles and bones of experimental animals the use of C-115-M1 atomic absorption spectrophotometer. Study of enzymes activity and lipid peroxidation products in serum and liver homogenates of experimental animals was conducted on a spectrophotometer Spekord UV/VIS. Hemolysis of red blood cells was determined by the Yacher method. Sorption capacity of the erythrocytes glycocalyx to alcian blue was determined by the Artsishevsky method. A study of the influence of Mn-load on the functional activity of energy metabolism was performed on a model system of rat liver mitochondria by the polarography. Intake of MnCl2 in a dose of LD50 generates weight loss of the rats by 44%, hemoglobin level decrease by 25%, and reduction of the transaminases activity by 40%. That indicates serious disorders in ions homeostasis and metabolic processes. MnCl2 load leads to a significant increase in the content of manganese in all tissues tested: the largest amount was found in the spleen (600% increase), liver (300%) and muscles (240%) as compared with the initial state. Apparently, these organs are depots of manganese. It was established that the introduction of MnCl2 in a dose of LD50 causes a redistribution of elements in the body, resulting in a significant reduction in the concentration of magnesium ions in heart, bones, muscles, liver and spleen. It was accompanied by increasing calcium content in liver, heart, muscle, kidneys and bones as well as by disorders of Ca/Mg ratios. MnCl2causes significant redistribution of the microelements in the rats’ organs. It is characterized by a decrease of copper, zinc and nickel contents in almost all studied tissues. The most antagonistic effect of manganese manifested in relation to nickel and copper in heart and spleen. A reduction of zinc content was most pronounced in spleen, while its contents in bones and kidneys almost don’t change. The study of the impact of manganese on biochemical parameters of membranes proved for the first time the malfunction of erythrocytes’ membranes. It results in increasing sorption capacity of the red blood cells glycocalyx to alcian blue. Using the erythrocyte model we established that manganese cations cause a significant increase in sorption capacity of the red blood cells (53.4 ± 1.8%) and their osmotic fragility, as evidenced by an increase of spontaneous hemolysis to 42%. The other evidence is the change of surface properties (glycocalyx), which indicated by an increase in the sialic acid content by 60% as compared with the control. The obtained data of the model study of the dynamics of the sorption capacity of erythrocytes glycocalyx to alcian blue, osmotic resistance of erythrocytes, activation of lipid peroxidation and increased level of sialic acid may be a signal that the primary mechanism of manganese intoxication is a damage of cell (plasma) membranes. The data obtained on a mitochondrial model suggests that MnCl2, acting as an antagonist of magnesium, has the ability to disturb respiration and oxidative phosphorylation that inhibits the energy metabolism of a cell. Mitochondrial oxidation of malate+glutamate was affected by MnCl2 in narrow range concentrations 3–4.5 mM that cause disengagement (3 mM) and complete inhibition (4.5 mM). The effectiveness of manganese intoxicated rats treatment with the poly-elemental phyto-complex “Valeoton” and zinc-pectin (drug-antagonist of manganese) was experimentally proved. Thus, the overall effect of manganese is its accumulation in organs and antagonistic relations to all divalent metals. Experimental results with manganese chloride loading point not only to changes in the concentrations of elements and their redistribution, but also to serious disturbances in regulation of ions homeostasis.

Long-term implantation of zinc-releasing calcium phosphate ceramics in rabbit femora.

Zinc is an essential trace element that has stimulatory effects on bone formation. Recently, we developed zinc-releasing calcium phosphate ceramics in order to add the pharmacologic effect of zinc to calcium phosphate ceramics. In our previous study, we showed that the optimum zinc content for promoting bone formation was 0.316 wt %. Therefore a zinc composite ceramic of zinc-containing beta-tricalcium phosphate and hydroxyapatite, with a zinc content of 0.316 wt %, was chosen for long-term implantation. Cylindrical rods of the zinc composite ceramic were implanted in rabbit femora for 2 to 60 weeks. Using computer-aided image analysis, a histomorphometric study was carried out to investigate bone formation and resorption around the implants. The control was a composite ceramic of beta-tricalcium phosphate and hydroxyapatite without zinc. The addition of zinc to the implant demonstrated both favorable and unfavorable effects on bone remodeling. The favorable effect was enhanced bone apposition to the implant surface, demonstrated by a significant increase in intramedullary bone apposition rate at 6 weeks and in cortical bone apposition rate at 24 and 60 weeks (p < 0.05). The unfavorable effect was increased bone resorption, demonstrated by a significant increase in medullary cavity area at 60 weeks (p < 0.05). In order to utilize the favorable effect and avoid the unfavorable effect of zinc, either a reduction in zinc content in the zinc composite ceramic or the selection of implantation sites that do not have excessive exposure to bone marrow are required.

The most appropriate (Ca+Zn)/P molar ratio to minimize the zinc content of ZnTCP/HAP ceramic used in the promotion of bone formation.

The (Ca+Zn)/P molar ratio of zinc-containing tricalcium phosphate and hydroxyapatite composite ceramics (ZnTCP/HAP) was investigated in the range from 1.50 to 1.66 to reveal the minimum zinc content possible in ceramics used in the promotion of osteoblastic cell proliferation and bone formation. The release rate of zinc increased with an increase in the (Ca+Zn)/P molar ratio up to 1.64 (ZnTCP/HAP1.64) and then decreased over 1.64 even when the zinc content of ZnTCP/HAP was the same. The zinc release rate of ZnTCP/HAP1.64 with a 0.21 Zn wt % nearly coincided with that of ZnTCP/HAP1.60 with a 0.316 Zn wt %, which was found be the most effective for promoting bone formation in rabbit femora. This means that the zinc content needed to promote bone formation can be reduced by 34% when the (Ca+Zn)/P molar ratio is increased to 1.64. The relative growth rate of MC3T3-E1 cells cultured on ZnTCP/HAP1.64 had a maximum value of 1.3 at a zinc content of 0.51 wt %; however, a 1.20 Zn wt % is required to attain the same value in relative growth rate in the case of ZnTCP/HAP1.60. A reduction in zinc content at a certain zinc release rate results from an increase in zinc content of the ZnTCP phase in ZnTCP/HAP. The ZnTCP/HAP1.64 would be better than any other ZnTCP/HAP relative to material safety because the risk of an accidental burst of zinc from the material is minimized due to the low zinc content.

Isolation and characterization of mammary cDNA differentially expressed in lethal milk mutation mice

AbstractLethal milk (lm) mutation in C57BL/6J inbred mice results in the reduction of zinc content in the milk and causes fatal neonatal zinc deficiency. Zinc injection to lm pups after birth helps them to overcome severe neonatal zinc deficiency and to maintain the normal body growth of lm pups. Thus, lm mutation displays a specific effect on the zinc content of the milk during lactation. The decrease in zinc content of the milk is not due to the low body zinc status in lactating lm dams. Also, oral zinc supplementation in lactating lm dams does not correct the low concentration of zinc in the milk. These findings suggest that lm mutation results in the defective cellular transport of zinc. The defective zinc transport might alter the expression of mammary genes because cellular zinc plays a critical role in diverse cellular functions. To investigate the effect of lm mutation on the expression of mammary genes, the differentially expressed cDNAs in lm mammary gland (MG) were explored using the mRNA differential display (DD) gel. One of the isolated cDNAs (M3) was expressed in the lm MG two times greater than that in the normal MG. The cloned partial M3 cDNA was shown to have the similarities to the unknown functional cDNAs in the yeast and human tissues. The M3 cDNA might have a common function in both lower and higher eukaryotes. The M3 mRNA is rich in the brain and the MG, but not in the liver and kidney. Hence, the M3 cDNA may have a certain function associated with the brain and the MG. More information regarding the cloned M3 cDNA might be provided by screening of the full length of M3 cDNA from cDNA library. J. Trace Elem. Exp. Med. 14:371–382, 2001. © 2001 Wiley‐Liss, Inc.

Effects of alcohol ingestion on zinc content of human and rat central nervous systems

The abundance of zinc in hippocampal mossy fibers has stimulated investigation of zinc status in various pathologic states in which behavioral or anatomic deficits involving the hippocampus are known to occur. Limited autopsy studies of chronic alcoholic humans have suggested that the content of zinc might be reduced in several brain regions whereas reported attempts to replicate these findings in ethanol-exposed experimental animals have produced inconsistent results. In this comparative study, the zinc concentration in 10 brain regions, all spinal cord segments, and microdissected hippocampal subfields was measured by isotope ratio mass spectrometry. A widespread 15 to 20% reduction in zinc content was observed in all regions of chronic alcoholics compared with controls but a selective involvement of hippocampus was not detected. In the experimental studies, groups of rats were exposed to ethanol by one of three routes: inhalation for 2 weeks, as an ethanol/liquid diet for 3 months, or a single intoxicating i.p. dose. Determinations of tissue uptake of radiozinc and of total zinc content were made. In contrast to human pathologic material, zinc pool size and tissue uptakes were not affected by experimental ethanol administration by any route. This study confirmed that a reduction in zinc concentration occurs in the central nervous system of chronic alcoholics. The animal studies indicated, however, that simple ethanol exposure, even for prolonged periods, does not perturb zinc metabolism in brain. Together, these observations argue that the abnormalities of zinc metabolism in chronic alcoholics are possibly secondary to homeostatic alterations associated with hepatic failure.

Changes in Chemical Composition of Winged Bean (Psophocarpus tetragonolobus L.) during Seed Development

ABSTRACTThree cultivars of winged bean were analyzed for total dry matter, crude fat, nitrogenous constituents, phosphorus, calcium, magnesium, zinc, iron, copper and cooking behavior at different stages of seed maturity. Accumulation of dry matter, crude fat and nitrogen occurred during seed development whereas nonprotein nitrogen and tryptophan contents decreased significantly. Reduction in poly‐phenol content was observed at all the stages of seed development. There was a significant decrease in total phosphorus content with concomitant increase in the proportion of phytate phosphorus throughout the seed development. In matured seeds, phytate phosphorus accounted for 66—73% of total phosphorus. A reduction in zinc content was noticed in all the cultivars studied. In contrast, calcium, magnesium, iron and copper contents of seeds of different stages of maturity did not exhibit marked differences.

Effect of Suboptimal Zinc Nutrition during Gestation and Lactation on Rat Molar Tooth Composition and Dental Caries

The main objective of this study was to determine the relationship between zinc content of teeth and susceptibility to dental caries. Pregnant albino rats were fed a purified diet containing 8, 15 or 30 ppm zinc throughout gestation and lactation. Food intake of all rats was restricted to that consumed by the lowest zinc group. At day 20 of lactation, pups were weaned to a high sucrose, caries-promoting diet and orally innoculated with Streptococcus mutans. Dams consuming the lowest zinc-containing diet exhibited a mild zinc deficiency as evidenced by reductions in gestational weight gain and zinc content of milk, serum and tibia when compared to other groups. All offspring survived. Pups originating from the lowest zinc group had significantly less zinc in molar enamel and dentin fractions compared to other groups at the end of a 30-day caries test period, but tibia zinc was essentially equal. This apparent pre-eruptive reduction in zinc content of enamel and dentin of offspring was associated with a significantly greater dental caries score on the buccal surface. This suggests that moderate dietary zinc deficiency is sufficient to reduce the pre-eruptive zinc content of both enamel and dentin and to increase dental caries.zinc caries

Zinc and collagen content of cirrhotic liver.

Liver samples obtained from 43 consecutive autopsies were analyzed for their content of zinc, hydroxyproline and nitrogen. Mean liver zinc was 2.36 and 1.27µg/mg nitrogen for histologically normal and cirrhotic samples, respectively. Hepatic zinc did not correlate with hepatic hydroxyproline. It is concluded that there is an absolute reduction in zinc content of cirrhotic liver and that this reduction bears no relationship to the amount of collagen present. If low levels of zinc in liver can be equated with zinc deficiency, patients with Laennec's cirrhosis are deficient in zinc.