Screening, purification, and characterization of an extracellular lipase from Aureobasidium pullulans isolated from stuffed buns steamers / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

An extracellular lipase from Aureobasidium pullulans was obtained and purified with a specific activity of 17.7 U/mg of protein using ultrafiltration and a DEAE-Sepharose Fast Flow column. Characterization of the lipase indicated that it is a novel finding from the species A. pullulans. The molecular weight of the lipase was 39.5 kDa, determined by sodium dodecyl sulfonate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme exhibited its optimum activity at 40 °C and pH of 7. It also showed a remarkable stability in some organic solutions (30%, v/v) including n-propanol, isopropanol, dimethyl sulfoxide (DMSO), and hexane. The catalytic activity of the lipase was enhanced by Ca2+ and was slightly inhibited by Mn2+ and Zn2+ at a concentration of 10 mmol/L. The lipase was activated by the anionic surfactant SDS and the non-ionic surfactants Tween 20, Tween 80, and Triton X-100, but it was drastically inhibited by the cationic surfactant cetyl trimethyl ammonium bromide (CTAB). Furthermore, the lipase was able to hydrolyze a wide variety of edible oils, such as peanut oil, corn oil, sunflower seed oil, sesame oil, and olive oil. Our study indicated that the lipase we obtained is a potential biocatalyst for industrial use.

Development and characterization of a novel bulk-fill elastomeric temporary restorative composite

Abstract Objectives: This study investigated the physical and mechanical properties, antibacterial effect and biocompatibility of novel elastomeric temporary resin-based filling materials (TFMs) containing zinc methacrylate (ZM). Material and Methods: Experimental TFMs were prepared by mixing the zinc methacrylate with monomer, co-monomer, photoinitiator and fillers. A ZM concentration of 0 (control), 0.5% (Z0.5); 1% (Z1), 2% (Z2), or 5% (ZM5) wt% was added to the TFMs. Fermit-N (F) was used for comparison with the experimental material. Microleakage, water sorption/solubility, degree of conversion, depth of cure, ultimate tensile strength, and hardness were determined and compared. A modified direct contact test (DCT) with Enterococcus faecalis and a Streptococcus mutans' biofilm accumulation assay was carried out to evaluate the antimicrobial effect and cytotoxicity of the assay. Statistical comparisons were performed (α=5%). Results: The results showed that the physical and mechanical properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference and some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values. TFMs with ZM killed E. faecalis only after 1 h. Biofilm development of S. mutans was not affected by the inclusion of ZM in the experimental TFMs. Conclusions: The present findings suggest that the physical, mechanical and biological properties of the experimental TFMs with ZM are comparable with the properties of the commercial reference. However, some properties were improved, such as lower microleakage and water sorption, and higher ultimate tensile strength values.

Two novel Mg(II)-based and Zn(II)-based complexes: inhibiting growth of human liver cancer cells

Two new Mg(II)-based and Zn(II)-based coordination polymers, {[Mg3(BTB)(DMA)4](DMA)2}n (1, H3BTB=1,3,5-benzenetrisbenzoic acid, DMA=N,N-dimethylacetamide) and {(H2NMe2)2[Zn3(BTB)2(OH)(Im)](DMF)9(MeOH)7}n (2, Im=imidazole, DMF=N,N-dimethylformamide), have been successfully synthesized and structurally characterized under solvothermal conditions. 1 contains a linear [Mg3(COO)6] cluster that connected by the fully deprotonated BTB3- ligands to give a kgd-type 2D bilayer structure; 2 represents a microporous 3D pillar-layered system based on the binuclear Zn units and pillared Im ligands, which shows a (3,5)-connected hms topological net. In addition, in vitro anticancer activities of compounds 1 and 2 on 4 human liver cancer cells (HB611, HHCC, BEL-7405 and SMMC-7721) were determined.

Two mechanisms of oral malodor inhibition by zinc ions

Abstract Objectives The aim of this study was to reveal the mechanisms by which zinc ions inhibit oral malodor. Material and Methods The direct binding of zinc ions to gaseous hydrogen sulfide (H2S) was assessed in comparison with other metal ions. Nine metal chlorides and six metal acetates were examined. To understand the strength of H2S volatilization inhibition, the minimum concentration needed to inhibit H2S volatilization was determined using serial dilution methods. Subsequently, the inhibitory activities of zinc ions on the growth of six oral bacterial strains related to volatile sulfur compound (VSC) production and three strains not related to VSC production were evaluated. Results Aqueous solutions of ZnCl2, CdCl2, CuCl2, (CH3COO)2Zn, (CH3COO)2Cd, (CH3COO)2Cu, and CH3COOAg inhibited H2S volatilization almost entirely. The strengths of H2S volatilization inhibition were in the order Ag+ > Cd2+ > Cu2+ > Zn2+. The effect of zinc ions on the growth of oral bacteria was strain-dependent. Fusobacterium nucleatum ATCC 25586 was the most sensitive, as it was suppressed by medium containing 0.001% zinc ions. Conclusions Zinc ions have an inhibitory effect on oral malodor involving the two mechanisms of direct binding with gaseous H2S and suppressing the growth of VSC-producing oral bacteria.

HIF-1alpha Upregulation due to Depletion of the Free Ubiquitin Pool

Hypoxia-inducible factor 1alpha (HIF-1alpha), which transactivates a variety of hypoxia-induced genes, is rapidly degraded under nomoxia through the hydroxylation-ubiquitination-proteasome pathway. In this study, we addressed how HIF-1alpha is stabilized by proteasome inhibitors. The ubiquitin pool was rapidly reduced after proteasome inhibition, followed by the accumulation of non-ubiquitinated HIF-1alpha. The poly-ubiquitination of HIF-1alpha was resumed by restoration of free ubiquitin, which suggests that the HIF-1alpha stabilization under proteasome inhibition is attributed to depletion of the free ubiquitin pool. Ni2+ and Zn2+ also stabilized HIF-1alpha with depletion of the free ubiquitin pool and these effects of metal ions were attenuated by restoration of free ubiquitin. Ni2+ and Zn2+ may disturb the recycling of free ubiquitin, as MG132 does. Based on these results, the state of the ubiquitin pool seems to be another critical factor determining the cellular level of HIF-1alpha.

Purification of a protease inhibitor from Dolichos biflorus using immobilized metal affinity chromatography.

Plant protease inhibitors (PIs) are generally small proteins which play key roles in regulation of endogenous proteases and may exhibit antifeedant, antifungal, antitumor and cytokine inducing activities. Dolichos biflorus (horse gram) is an unexploited legume, which is rich in nutrients and also has therapeutic importance. It contains a double-headed PI, which is an anti-nutritional factor. As there is no report available on its simultaneous removal and purification in single step, in this study, a double-headed PI active against both trypsin and chymotrypsin was purified from Dolichos biflorus to ~14-fold with ~84% recovery using an immobilized metal affinity chromatography (IMAC) medium consisting of Zn-alginate beads. The method was single-step, fast, simple, reliable and economical. The purified inhibitor showed a single band on SDS-PAGE corresponding to molecular mass of 16 kDa and was stable over a pH range of 2.0-12.0 and up to a temperature of 100°C for 20 min. The optimum temperature for trypsin and chymotrypsin inhibitor was observed to be 50°C and 37°C, respectively and pH optimum was pH 7.0 and 8.0, respectively. Thus, IMAC using Zn-alginate beads was useful in simultaneous purification and removal of an anti-nutritional factor from horse gram flour in single step. This procedure may also be employed for purification of other plant PIs in one step.

Application of pollution indices for evaluation of heavy metals in soil close to phosphate fertilizer plant, Assiut, Egypt

Pollution indices were used to investigate the levels of heavy metal concentrations in a polluted area under the effect of fertilizer plant emissions at Manqabad, Assiut. Huge amounts of dusts, fumes and gases containing heavy metals which are released from the industrial processing activities, precipitated in the neighbouring area by the effect of meteorological factors causing soil pollution. Soil samples were taken from the area downwind of the factory and analyzed to detect concentration of heavy metals in the study area. Results of soil analysis showed that the area has been harmfully affected by the heavy metals: Cd, Cu, Pb and Zn and their average concentrations are 0.3 mg/kg, 57.0 mg/kg, 94.7 mg/kg and 80.7 mg/kg respectively. These values exceeded the concentrations in soil background [0.013 mg/kg for Cd, 9.62 mg/kg for Cu, 5.17 mg/kg for Pb and 11.56 mg/kg for Zn] obtained from unpolluted area far from industrial activities and also exceeded the international standards for soil pollution stated by WHO. Pollution indices were developed to evaluate the levels of soil pollution with heavy metals. Index of geo-accumu!ation [Igeo], Enrichment Factor [EF], Pollution Index [PI], and Load Pollution Index [LPI], were estimated. The calculated results of contamination degree showed that the investigated area lies under the class of high pollution. In final conclusion, the investigated area is highly affected by emissions from the fertilizer plant So control measures should be applied to the fertilizer plant and the polluted soil area adjacent to the factory should be remediate

Bioacumulação de zinco em micélio de Agaricus subrufescens / Zinc bioaccumulation in Agaricus subrufescens mycelium / Bioacumulación de zinc en micelio de Agaricus subrufescens

Fungos basidiomicetos têm a capacidade de bioacumular metais pesados, no entanto existem poucos trabalhos sobre bioacumulação de zinco em micélio de Agaricussubrufescens. O objetivo deste trabalho foi avaliar a bioacumulação de zinco em micélio vegetativo de A. subrufescens cultivado em meio sólido e líquido. O fungo foi crescido em meio sólido ou em meio líquido a base de extrato de malte adicionado de ZnSO4 a fim de obter zero; 2,5; 5; 7,5; 10; 15 ou 20 ppm de zinco. Os meios foram inoculados e após 14 dias foi determinada a biomassa e a bioacumulação de zinco. A adição de zinco no meio de cultivo inibiu o crescimento micelial e induziu a bioacumulação na biomassa tanto no cultivo sólido como no líquido. Adições acima de 7,5 ppm de zinco inibiram totalmente o crescimento micelial. O fungo crescido em meio de cultivo líquido sofre maior inibição do crescimento com a adição de zinco e maior bioacumulação que no meio sólido...

Fungi basidiomycetes have the ability to bioaccumulate heavy metals, but there are few studies on zinc bioaccumulation in the mycelium of Agaricus subrufescens. The objective of this study is to evaluate the zinc bioaccumulation in the mycelium of A. subrufescens cultivated in solid and liquid culture media. Mycelium was grown on solid or liquid medium in malt extract base added with ZnSO4 to obtain zero, 2.5, 5, 7.5, 10, 15 or 20-ppm zinc. Mycelial biomass and zinc bioaccumulation were determined 14 days after inoculation in the culture media. Addition of zinc in culture medium inhibited mycelial growth and induced biomass bioaccumulation both in solid and in liquid culture. Additions higher than 7.5-ppm zinc completely inhibited mycelial growth in culture medium. Mycelial growth in liquid culture presented greater increase of growth inhibition with the addition of zinc and greater bioaccumulation than in solid medium...

Hongos basidiomicetos tienen la capacidad de bioacumular metales pesados, sin embargo hay pocos estudios sobre la bioacumulación de zinc en el micelio de Agaricus subrufescens. El objetivo de este estudio ha sido evaluar la bioacumulación de zinc en el micelio de A. subrufescens cultivado en medio sólido y líquido. El hongo ha crecido en medio sólido o líquido a base de extracto de malta agregado de ZnSO4 para obtener cero; 2.5, 5, 7.5, 10, 15 o 20 ppm de zinc. Los medios fueron inoculados y después de 14 días se determinó la biomasa y la bioacumulación de zinc. La adición de zinc en el medio del cultivo inhibió el crecimiento micelial y indujo la bioacumulación de la biomasa tanto en el cultivo sólido como en el líquido. Adiciones superiores a 7.5 ppm de zinc inhibieron completamente el crecimiento del micelio. El hongo crecido en medio de cultivo líquido sufre mayor inhibición del crecimiento con la adición de zinc y mayor bioacumulación que en el medio sólido...

Supplementation of soft drinks with metallic ions reduces dissolution of bovine enamel

OBJECTIVE: The aim of this study was to evaluate the effect of the addition of metallic ions to carbonated drinks on their erosive potential. MATERIAL AND METHODS: Powdered enamel was added to carbonated beverages (Coca-ColaTM or Sprite ZeroTM and shaken for 30 s. The samples were then immediately centrifuged and the supernatant removed. This procedure was repeated 5 times with the beverages containing Cu2+, Mg2+, Mn2+ or Zn2+ (1.25-60 mmol/L). For Coca-ColaTM, the concentration of each ion that exhibited the highest protection was also evaluated in combination with Fe2+. The phosphate or calcium released were analyzed spectrophotometrically. Data were analyzed using ANOVA and Tukey's test (p<0.05). RESULTS: For Coca-ColaTM, the best protective effect was observed for Zn2+ alone (10 mmol/L) or in combination (1 mmol/L) with other ions (12% and 27%, respectively, when compared with the control). Regarding Sprite ZeroTM, the best protective effect was observed for Cu2+ at 15 and 30 mmol/L, which decreased the dissolution by 22-23%. Zn2+ at 2.5 mmol/L also reduced the dissolution of powdered enamel by 8%. CONCLUSIONS: The results suggest that the combination of metallic ions can be an alternative to reduce the erosive potential of Coca-ColaTM. Regarding Sprite ZeroTM, the addition of Cu2+ seems to be the best alternative. .

Efecto de la estacionalidad sobre el estado nutricional de Hierro, Zinc y Cobre / Effect of seasonality on nutritional status of Iron, Zinc and Copper

Food consumption and therefore the nutritional status of micro-nutrients are influenced by various factors such as seasonality. This study aimed to determine the effect of seasonality on the nutritional status of Fe, Zn and Cu in adult subjects. A longitudinal study was conducted during the months of September 2005 and August 2006. Fifty subjects of both sexes belonging to the urban area of the city of Santiago de Chile were evaluated. Blood samples were drawn during the first week of each month; serum iron, copper and zinc, hemoglobin, mean cell volume, serum ferritin, zinc-protophorphyrin and ceruloplasmin were determined. Serum copper and zinc levels showed significant seasonal variations but not serum iron. Mean cell volume, hemoglobin and ceruloplasmins were significantly lower during spring and summer while serum ferritin and zinc-protophorphyrin showed lower concentrations during autumn and winter. We conclude that during the spring and summer levels of serum iron, copper and zinc could be diminished by reduced food intake.

El consumo de alimentos y por lo tanto el estado de nutrición de los micronutrientes está condicionado por diferentes factores como la estacionalidad. El presente estudio tuvo como objetivo determinar el efecto de la estacionalidad sobre el estado nutricional de hierro, zinc y cobre de sujetos adultos habitantes de la ciudad de Santiago de Chile. Un estudio longitudinal en 50 sujetos de ambos sexos se realizó entre los meses de septiembre del 2005 y agosto del 2006. Durante la primera semana de cada mes se extrajo muestras de sangre para la determinación de hierro, zinc y cobre sérico, hemoglobina, volumen corpuscular medio, ferritina sérica zinc-protoporfirina y ceruloplasmina. Los niveles de cobre, zinc, hemoglobina, volumen corpuscular medio, y ceruloplasmina fueron significativamente menores durante primavera y verano mientras ferritina sérica y zinc-protoporfirina presentaron niveles más bajas durante otoño e invierno. Concluimos que la estacionalidad es un factor a considerar cuando se realicen mediciones de estado de nutrición de los microminerales hierro, zinc y cobre.

Suplementos nutricionales orales a base de nuevos complejos de cobre, magnesio, manganeso y zinc

Suplementos nutricionales orales a base de nuevos complejos de cobre, magnesio, manganeso y zinc Los oligoelementos cobre, magnesio, manganeso y zinc intervienen en numerosos procesos metabólicos, enzimáticos, inmunológicos y tisulares, forman parte estructural de proteínas y pueden participar en la regulación de la expresión genética. La deficiencia de estos elementos esenciales dificulta el apropiado funcionamiento del organismo e induce el desarrollo de diversas enfermedades. Se debe garantizar la incorporación de oligoelementos a través de la dieta; sin embargo, la cantidad suministrada no siempre es suficiente y el uso de suplementos nutricionales convencionales presenta dos problemas; el primero se atribuye a la asociación de los metales a sales inorgánicas que generan una baja absorción e intolerancias a nivel gástrico y el segundo corresponde a las interacciones antagonistas entre diversos metales componentes de la formulación. Como una alternativa a los problemas mencionados, en este trabajo se propone la elaboración de tabletas para la administración oral de nuevos complejos de cobre, zinc, magnesio y manganeso ligados a los aminoácidos glicina y asparagina. En la síntesis de estos complejos, cada ligando se unió a duplas de cationes no antagonistas, se verificó la formación de los complejos por espectroscopía infrarroja, calorimetría de barrido diferencial, análisis termogravimétrico y difracción de rayos X de polvos, y se determinaron los tiempos de desintegración y de disolución in-vitro a las formas farmacéuticas finales.

Oral dietary supplements with copper, magnesium, manganese and zinc-based new complexes Oligoelements such as copper, magnesium, manganese and zinc are involved in several metabolic, enzymatic and immunological processes. They are also important for the integral tissue proteins and could be involved in gene expression regulation. The deficiency of these essential elements hampers the appropriate function of the body and may cause various diseases. Therefore, it is important to guarantee the incorporation of these trace elements in the diet, but the quantity provided is not always adequate for the optimum body performance. Currently, conventional nutritional supplements have two major problems. The first one is attributed to the association of inorganic salts with metals which might cause low absorption and gastric intolerance. The second problem is caused when several metals are present in a formulation which could lead to possible antagonistic interactions. For this reason, this study explores the development of cations (i.e., copper, zinc, magnesium and manganese) and amino acids (i.e., glycine and asparagine) new complexes formulated into compacts for oral administration. In each reaction, ligands were linked to non-antagonistic cation pairs. The complex formation was characterized by infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and powder X-ray diffraction analyses. Compact disintegration and in-vitro dissolution tests for these complexes were also determined.

El zinc en la salud humana -1 / Zinc in human health - I

Zinc Is a divalent cation with multiple functions In the human body. Zinc absorption occurs In the small Intestine and, together with zinc excretion via feces, is the point of control for zinc homeostasis. Zinc Is an essential nutrient with a specific role In more than 300 enzymes, which participate In all Important biochemical reactions of the human body. Therefore, zinc status has a direct effect In growth, neurological and behavioral development and In the Immune system. The diagnosis of zinc deficiency In Individuals Is difficult given that there Is still no Indicator with adequate sensitivity. Nevertheless, It Is acceptable to use serum zinc to evaluate populations. Finally, Intervention strategies such as supplementation, food fortification and/or dietary modification can be used to control and/or prevent zinc deficiency.

El zinc es un catión divalente con múltiples funciones en el cuerpo humano. La absorción de zinc ocurre en el intestino delgado y es junto con la excreción de zinc vía heces, los puntos de control de la homeostasis de zinc. El zinc es un nutriente esencial con un rol específico en más de 300 enzimas, las cuales participan en todas las reacciones bioquímicas importantes del cuerpo humano. Por ende, el estado de zinc tiene un efecto directo en el crecimiento, el desarrollo neurológico y de comportamiento y en el sistema inmune. El diagnóstico de deficiencia de zinc en individuos no es posible pues aun no existe un marcador lo suficientemente sensible. Sin embargo, el zinc sérico es aceptable para evaluar a poblaciones. Finalmente, se pueden usar las estrategias de suplementación, fortificación y/o modificación alimentaria para controlar y/o prevenir la deficiencia de zinc.

El zinc en la salud humana - II / Zinc in human health - II

Zinc is a divalent cation with multiple functions in the human body. Zinc absorption occurs in the small intestine and is, together with its excretion via faeces, the point of control for zinc homeostasis. Zinc is an essential nutrient with a specific role in more than 300 enzymes, which participate in all important biochemical reactions of the human body. Therefore, zinc status has a direct effect in growth, neurological and behavioral development and in the immune system. The diagnosis of zinc deficiency in individuals is not yet possible given that there still is no indicator with adequate sensitivity. Nevertheless, it is acceptable to use serum zinc levels to evaluate populations. Finally, intervention strategies such as supplementation, food fortification and/or dietary modification can be used to control and/or prevent zinc deficiency.

El zinc es un catión divalente con múltiples funciones en el cuerpo humano. La absorción de zinc ocurre en el intestino delgado y es junto con la excreción de zinc por las heces, uno de los dos puntos de control de la homeostasis de zinc. El zinc es un nutriente esencial con un rol específico en más de 300 enzimas, las cuales participan en todas las reacciones bioquímicas importantes del cuerpo humano. Por ende, el estado de la nutrición de zinc tiene un efecto directo en el crecimiento, el desarrollo neurológico y de comportamiento y en el sistema inmune. El diagnóstico de deficiencia de zinc en seres humanos no es posible pues aun no existe un marcador lo suficientemente sensible. Sin embargo, el zinc sérico es aceptable para evaluar poblaciones. Finalmente, se pueden usar las estrategias de suplementación, fortificación y/o modificación alimentaria para controlar y/o prevenir la deficiencia de este elemento.

Detection of metal elements of skin in electric injury by inductively coupled plasma mass spectrometry / 法医学杂志

OBJECTIVE@#To explore the feasibility of the detection of metal elements of skin in electric injury using inductively coupled plasma mass spectrometry (ICP-MS), and to establish a method to detect metal elements of skin in electric injury.@*METHODS@#Brass, copper, aluminum and iron were used as electrodes to make electrical marks on rabbit hindlimb (220V AC), and then ICP-MS was used to detect the metal elements in injured skin.@*RESULTS@#Comparing with control group,the levels of Cr, Ni, Cu, Zn and Pb showed higher in the group of brass shock (P < 0.05); the levels of Cr, Cu and Pb were higher in group of the copper shock (P < 0.05); the levels of Al, Cr, Mn, Co, Ni, Cu and Pb displayed stronger in group of aluminum shock (P < 0.05); the levels of Cr, Mn, Fe and Ni showed higher in the group of iron shock (P < 0.05). The types and levels of metal elements showed the significant difference between different electrode groups after electric injury.@*CONCLUSION@#ICP-MS can be used as an effective tool to determine electric injury, and the method can be used to estimate the features of electrodes.

Iron-zinc interaction during uptake in human intestinal Caco-2 cell line: Kinetic analyses and possible mechanism.

Iron and zinc interact at the enterocyte during absorption, but the mechanism(s) remain elusive. The aim was, therefore, to understand the mechanism of interaction using kinetic analyses of iron and zinc uptake, individually and in combination under normal and altered cellular mineral concentrations in human intestinal Caco-2 cell line. Striking differences in kinetic parameters were observed between iron and zinc uptake. Iron uptake followed a two-component model, while zinc uptake followed a three-component model. Iron uptake had a Km of 3.6 µM and Vmax of 452 pmol/mg protein/min, while zinc uptake had a Km of 42 µM and Vmax of 3.09 pmol/mg protein/min. Zinc dose-dependently inhibited iron uptake through mixed-inhibition but iron marginally increased zinc uptake. Cellular zinc repletion doubled iron uptake and eliminated inhibition, but zinc depletion decreased iron uptake. Iron pre-treatment had no effect on zinc uptake. Based on these results, a two-transporter model of iron uptake, comprising the apical iron uptake transporter divalent metal ion transporter-1 (DMT-1) and an unknown putative transporter was derived. This model for DMT-1 was verified by immunoblotting. These results implied that cellular zinc status profoundly influenced iron uptake and its interactions with zinc during uptake. DMT-1 might not simultaneously transport iron and zinc, providing a mechanistic basis for observed interactions.

Testicular protein profile (SDS-PAGE) study of zinc deficient Wistar albino rat.

Present study has revealed that zinc plays important role in regulating the production and secretion of proteins at transcriptional or translational level. Study has firmly depicted the change in the levels of polypeptide of 70 kDa in zinc deficient group. The protein pattern in pair fed group has been affected mainly to combat the insult due to low food intake.

Chemical composition, metals content and pesticide residues in raw, pasteurized and UHT milk and their dietary intake

Chemical composition, metal contents and pesticide residues were determined in raw, pasteurized and UHT [Ultra High Temperature] milk samples collected from local markets in Cairo Governorate, Egypt. Fat, T.P. [Total Protein], ash, lactose and T.S. [Total Solids] contents were [3.50, 3.20, 0.71, 4.10 and 11.40%], [3.00, 3.50, 0.80, 4.65 and 11.50%], and [3.00, 3.40, 0.80, 4.44 and 11.50%] in raw, pasteurized and UHT milk, respectively. Levels of Zn, Fe, Cu, Mn, Cr, Ni, Co, Pb, Cd and Sn were [3.59, 0.62, 0.17, 0.06, 0.03, 0.036, 0.032, 0.032, 0.025 and 0.002 mg/kg], [3.11, 0.55, 0.15, 0.041, 0.030, 0.030, 0.030, 0.021, 0.022 and 0.002 mg/kg] and [3.11, 0.60, 0.180, 0.050, 0.020, 0.030, 0.030, 0.020, 0.020 and 0.002 mg/kg] in raw, pasteurized and UHT milk, respectively. Organochlorine pesticides [HCB, lindane, aldrin, heptachlor, heptachlor epoxide, chlordane, endrin and DDT metabolites] were detected in raw milk at levels higher than the tolerance limits. However, these chemicals were detected in pasteurized milk at slightly higher levels and in UHT milk at levels lower than the tolerance limits. On the other hand, non of raw, pasteurized and UHT milk revealed the presence of organophosphorus pesticides [malathion, profenofos, pirmiphos-methyl and dimethoate]. To assess any possible risks to consumers of milk, dietary intakes have been estimated using the mean concentration of various metals and pesticide residues in this monitoring. Data showed that, daily intake of the investigated metals and pesticides in milk were lower than the recommended levels except that Pb and Cd are higher than it

New pH-Metric method for determination of some angiotensin converting enzyme inhibitors through their complex formation with some transition metal ions

Study of mixed ligand complexes of Co[2+] and Zn[2+] with three Angiotensin converting enzyme inhibitors [ACE] was conducted in aqueous solution by pH metric titration. These are Enalapril maleate [I], Perindopril [II] and Moexipril [III] and one of the amino acid family [glycine]. Protonation constants of the three drugs and stability constants of the binary and ternary complexes were determined at [25 +/- 1] [degree sign] C and ionic strength 0.1M NaCl. The stability constants of the binary complexes of I, II and III with Co[2+] and Zn[2+] were performed and the results indicate the presence of one formation constant for the complexes of Co[2+] and Zn[2+] ions with II and III and two formation constants for I. By introducing glycine in the above binary complexes, ternary complexes were formed. The formation constant of the ternary complexes of I, II and III with Co[2+] and Zn[2+] ions with glycine was also calculated at the same temperature and ionic strength. This potentiometric technique was utilized also for the determination of the cited drugs

A study on retention and release of Zn (II) by mineral and carbonaceous solid phases alone and in a blend.

The study was carried out to understand the interaction of Zinc (II), which happens to be an essential micronutrient and essential element for all life, with a mineral surface, Montmorillonite Clay which happens to be an important soil constituent and is compared with carbonaceous solid phase such as Activated Carbon. It was found that retention takes place through chemisorptions, ion exchange and probably precipitation also involved at higher pH. The effect of various parameters such as pH, contact time, adsorbent dosage and initial concentration of the metal ion on the kinetics of adsorption was studied. At higher pH of the clay system, zinc becomes less soluble. The adsorption behaviour of zinc using a blend of Montmorillonite Clay, Activated Carbon was also studied. It was found that when the percentage of Activated Carbon in the blend increases, the percentage retention decreases. The release of Zn (II) was studied using different extracting solutions. The desorption was insignificant indicating the possibility of formation of inner sphere complexes. The adsorption data was also applied to the effluent from Zinc Smelting Industry.

Efecto de sedimentos naturales enriquecidos con zinc, en modelos aislados y en microcosmos, sobre tres especies de invertebrados bentónicos / Effect of zinc-enriched sediments, in open and isolated systems, on three species of benthonic invertebrates

Availability of toxics in aquatic bodies is limited by the physicochemical characteristics of sediments and water, as well as by the interactions between the different xenobiotics and inhabits species. The aim of this work was to relate the effect produced by zinc (Zn) spiked in sediments of the Ignacio Ramirez dam (PIR), in isolated and microcosms models, on ATP concentration of three benthic organisms with the metal biodisponibility. The selected species were a crustacean, an annelid and a mollusk: Hyalella azteca (Amphipoda: Hyalellidae), Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae) and Stagnicola attenuata (Basommatophora: Lymnaeidae), species that are found at high proportions in the reservoir and use different spaces in the benthos. Samples of sediments and organisms were collected from the PIR during the dry season (February of 1999). Metal concentration (Zn, Fe, Cu and Ni), pH, texture, particle size, total nitrogen and organic matter were determined in sediments. Sublethal studies were carried out using two types of static systems (organisms isolated and in microcosms). Both models contained PIR sediments enriched with Zn (nominal concentration of 0.8129 mg/kg) and synthetic water in a proportion of 1:4. The test organisms were added to the systems once the equilibrium was reached (2 hr) considering the biomass quantity with respect to volume (1.0 g of organism by each 100 ml of water:sediment). After 0, 12, 24, 36, 48 and 72 hr of exposure, samples of sediment and hydrobionts were taken, and Zn content was quantified by atomic absorption. ATP concentration was also determined in organisms. The effect produced by natural sediments spiked with Zn is increased by the presence of more than one specie in the system (microcosm). With respect to Zn levels, two of the organisms tend to lose this metal in isolated and microcosm models, probably as a regulation strategy in its accumulation, as well as Fe presence in the reservoir sediments. Therefore...

En los cuerpos acuáticos la disponibilidad de los tóxicos es limitada por las características fisicoquímicas de los sedimentos y agua, así como por las interacciones entre los diversos xenobióticos y entre las especies que los habitan. Por lo anterior, el objetivo del presente trabajo fue relacionar el efecto producido por el zinc (Zn) sembrado en sedimentos del embalse Ignacio Ramírez (PIR), en modelos aislados y en microcosmos, sobre el ATP de res organismos bentónicos con la biodisponibilidad del metal. Las especies seleccionadas fueron: Hyalella azteca, Limnodrilus hoffmeisteri y Stagnicola attenuata, dado que se encuentran en altas proporciones en el embalse y ocupan espacios diferentes en el bentos. Las muestras de sedimentos y organismos se colectaron en la estación de sequía (febrero de 1999). A los primeros se les determinó el pH, textura, tamaño de partícula, nitrógeno total, materia orgánica y concentración de metales (Zn, Fe, Cu y Ni). Posteriormente se realizó un estudio de toxicidad subletal utilizando dos tipos de sistemas estáticos (organismos aislados y en microcosmos). Ambos modelos contenían sedimentos de la PIR enriquecidos con Zn (concentración nominal de 0.8129 mg/kg) y agua sintética en una proporción de 1:4. Los organismos de prueba fueron adicionados una vez alcanzado el equilibrio (2 hr) considerando la cantidad de biomasa con respecto al volumen (1.0 g de organismo por cada 100 ml de agua:sedimento). Después de 0, 12, 24, 36, 48 y 72 hr de exposición se tomaron muestras del sedimento y de los hidrobiontes, a los cuales se les cuantificó el contenido de Zn por absorción atómica. A los organismos también se les determinó la concentración de ATP. Los resultados obtenidos muestran que el efecto producido por los sedimentos naturales enriquecidos se ve potenciado por la presencia de más de una especie en el sistema (microcosmos). Con respecto a los niveles de Zn, dosde los organismos (L. hoffmeisteri y S. attenuata) tienden a...