Spatial distribution of manganese concentration and load in street dust in Mexico City / Distribución espacial de las concentraciones y carga de manganeso en el polvo urbano de la Ciudad de México

Abstract: Objective: To obtain a first indication of the distribution and extent of manganese (Mn) contamination in Mexico City. Mn concentration and load in street dust were analyzed in order to reveal the most contaminated areas. Materials and methods: 482 samples of street dust were analyzed through inductively coupled plasma-optical emission spectroscopy. The contamination factor (CF), the geoaccumulation index (Igeo) and the spatial interpolations of the kriging indicator were calculated. Results: A slight influence of anthropogenic activities is detected on the Mn content of street dust. The highest levels of pollution by concentration (Igeo=uncontaminatedtomoderately contaminated) are grouped towards the city's north (industrial) and center (commercial and high traffic) areas. The areas with the highest Mn load were located towards the east and northwest areas (Igeo=moderately contaminated). Conclusions: These findings will serve as a baseline to assess future variations in Mn content in Mexico City's environment.

Resumen: Objetivo: Obtener una primera aproximación sobre la distribución espacial de la contaminación por manganeso (Mn) en la Ciudad de México. Se analizó la concentración y carga de Mn en el polvo de la calle para identificar las áreas más contaminadas. Material y métodos: 482 muestras de polvo de la calle fueron analizadas con espectroscopía de emisión por plasma de acoplamiento inductivo. Se calculó el factor de contaminación, índice de geoacumulación, y las interpolaciones espaciales del indicador kriging. Resultados: Existe una ligera influencia de actividades antropogénicas en el contenido de Mn del polvo de la calle. Los niveles más altos de contaminación por concentración (Igeo=no contaminado a moderadamente contaminado) se agruparon en el norte (industrial) y centro (comercial y de alto tráfico) de la ciudad. Las áreas con las cargas de Mn más altas estuvieron al este y noroeste (Igeo=moderadamente contaminado), donde había más polvo. Conclusiones: Estos resultados servirán como punto de referencia para evaluar variaciones futuras en el contenido de Mn en la Ciudad de México.

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. .

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.

Molecular cloning, purification and characterization of thermostable -1,3-1,4 glucanase from Bacillus subtilis A8-8.

A gene encoding a -1,3-1,4-glucanase (CelA) belonging to family 5 of glycoside hydrolases was cloned and sequenced from the Bacillus subtilis A8-8. The open-reading-frame of celA comprised 1499 base pairs and the enzyme was composed of 500 amino acids with a molecular mass of 55 kDa. The recombinant -1,3-1,4 glucanase was purified by GST-fusion purification system. The pH and temperature optima of the enzyme were 8.0 and 60oC, respectively. The enzyme was stable within pH 6.0-9.0. It was stable up to 60oC and retained 30% of its original activity at 70oC for 60 min. It hydrolyzed lichenan, CMC, xylan, laminarin, avicel and pNPC, but was inactive towards cellobiose. The enzyme activity was markedly activated by Co2+ and Mn2+, but was strongly inactivated by Fe3+. The truncated gene, devoid of cellulose-binding domain (CBD) showed 60% of activity and bound to avicel.

Physicochemical, surface and catalytic properties of Co3O4/Mn2O3 and Mn2O3/Co3O4 systems

The two catalytic systems were prepared using equimolar proportions of cobalt nitrate and manganese carbonate [Co3O4/Mn2O3] and manganese carbonate and cobalt nitrate Mn2O3/Co3O4]. The mixed solids were subjected to heating at 500, 700, and 900°C. The solid - solid interactions taking place in the two catalytic systems were followed up using XRD investigation. Their specific surface areas were determined from nitrogen - adsorption isotherms carried out at - 196°C. Their catalytic activities were studied via following up the kinetics of CO oxidation by O2 at 125-400°C using a static method. The results obtained revealed that solid - solid interaction took place between cobalt and manganese oxides at 500 - 900°C yielding cobalt manganite and manganese cobaltite. In Co3O4/Mn2O3 system, a complete conversion of cobalt and manganese oxides took place at 900°C to yield cobalt manganite. In the other system, however, a partial conversion of Mn2O3/Co3O4 took place at 900°C. The specific surface areas of the two investigated systems are close to each other and decrease by increasing their calcinations temperature within 500 - 900°C.The decrease was, however, more pronounced by increasing the calcinations temperature from 700 to 900°C. The catalytic activity of Mn2O3/Co3O4 is smaller than that measured for the other system calcined at 500 °C. Opposite results were observed for the solids calcined at 700°C and 900°C. The catalytic reaction proceeds via almost the same mechanism in contact with different solids

Value of Manganese-Enhanced T1- and T2-Weighted MR Cholangiography for Differentiating Cystic Parenchymal Lesions from Cystic Abnormalities which Communicate with Bile Ducts

We present a case report to show how manganese-enhanced T1- and T2-weighted MR cholangiography could differentiate cystic parenchymal lesions from cystic abnormalities which communicate with the bile ducts.

Batch kinetic modeling of arsenic removal from water by mixed oxide coated sand (mocs).

A new granular media developed by coating of iron and manganese on quartz sand surface proved to be effective for arsenic (III) removal from water. The media has shown alkali resistance. The kinetic and thermodynamic studies data were tested using pseudo-second- order, intraparticle diffusion and Elovich equation models. The rate constants, equilibrium sorption capacity and normalized standard deviations were calculated for all the three models. It was shown that all three models almost accurately predict the sorption capacity with respect to time for whole range of data points. However, sorption kinetic data were better correlated using Elovich equation model based on normalized standard deviation. The Langmuir and Freundlich isotherm equations could be used to describe the partitioning behavior of system at different pH and media size. The results of thermodynamic studies show that the As(III) adsorption on Mixed Oxide Coated Sand (MOCS) was endothermic in nature. Kinetic and isothermal studies data have also been used to obtain thermodynamic parameters of the process.

Modulation of alpha1beta1 integrin mediated adhesion of hepatocytes to collagen IV and laminin by divalent cations.

Cell matrix interactions play a critical role in hepatic development and regeneration after acute injury. These interactions are mediated by transmembrane receptors belonging mainly to the integrin family. We have tried to assess the role of divalent cations in mediating attachment of hepatocytes to matrix proteins like collagen IV (Col IV) and laminin (Ln). The three cations examined viz. Ca2+, Mg2+ and Mn2+ showed attachment promoting activity. Since alpha1beta1 integrin is a common receptor for col IV and LN in liver, the effect of cations in its binding to these matrix proteins was studied. Although cations in general enhanced the binding, different cations exhibited differential effect in promoting the binding for different ligands. Mg2+ ions were more effective in promoting the binding of alpha1beta1 integrin to col IV but Ca2+ proved to be more effective one for Ln. Kinetic analysis of binding in dot blot assays using different concentrations of cations showed that while Mg2+ was active at low concentrations Ca2+ and Mn2+ promoted the binding more at higher concentrations. Absence of competitive effect in binding studies showed that they bind at different sites on the receptor. Differential effects of cations in promoting the binding of alpha1beta1 integrin to Col IV and Ln suggest that changes in level of diffusible cations can modulate affinity of the common receptor alpha1beta1 integrin to its ligands and can influence adhesion of hepatic cells to different matrix proteins during hepatic development and regeneration.

Modelling a binuclear metal binding site in the photosynthetic reaction centre II.

Based on the experimental data and homologous sites in Protein Data Bank (PDB) a model for metal binding sites in D1/D2 heterodimer has been proposed. On searching for tetranuclear and binuclear Mn binding sites in the PDB, a suitable sequence homology in thermolysin and D1 could be observed. From the homology and site-directed mutagenesis data, a model for binuclear Mn-Ca or Mn-Mn has been built and it is extended to a tetranuclear Mn centre.

Biochemical studies on human cervical mucous in infertility

We studied 25 infertile women in whomn in whom cervical hostility was the only known cause of infertility, and 10 fertile women. Total soluble proteins, IgG, IgA and IgM togeter with zinc, copper manganese and lead were measured in mid-menstrual cycle cervical mucus. IgG and IgA were present in the cervical mucus of all the women. But IgM was detected only in 20% of samples of fertile women and in 36% of samples of infertile women. Levels of IgA and total soluble proteins were significantly higher in the infertile group. Zinc, Copper and manganese were present in cervical mucus and the concentrations found did not differ significantly in the tow groups. Lead was not detected in all cervical mucus samples in the two groups