Total Concentrations Of Mg Research Articles

Investigation of the effects of pretreatment on the elemental composition of ash derived from selected Nigerian lignocellulosic biomass

Lignocellulosic biomass is an important source of renewable energy and a potential replacement for fossil fuels. In this work, the X-ray fluorescence (XRF) method was used to analyze the elemental composition of raw and pretreated lignocellulosic biomass of cassava peels, corn cobs, rice husks, sugarcane bagasse, yam peels, and mixtures of cassava peels and yam peels, corn cobs and rice husks and all five biomass samples combined. The influence of particle size on elemental properties was investigated by screening the selected biomass into two size fractions, of an average of 300 and 435 µm, respectively. The total concentration of Mg, Al, Si, P, S, Cl, Ca, Ti, Cr, Mn, Fe, Co, Cu, Zn, Sn, Ni, Br, Mo, Ba, Hg, and Pb were determined for each of the biomass samples before and after the different pretreatments adopted in this study. From the results of the analysis, there was a significant reduction in the concentration of calcium in all the analyzed biomass after the alkaline pretreatment with rice husks biomass having the lowest concentration of 66 ppm after the alkaline pretreatment. The sulfur content of the acid pretreated biomass increased considerably which is likely due to the sulfuric acid used for the acid pretreatment. The fact that a mixture of biomass feedstock affects the properties of the biomass after pretreatment was validated in the mixed biomass of cassava peels and yam peels biomass as an example. The concentration of Mg in the mixed biomass was 1441 ppm but was 200 ppm and 353 ppm in individual cassava peels and yam peels respectively. The results of this study demonstrated that pretreated mixtures of biomass have varied elemental compositions, which could be an important factor affecting downstream processes, especially if a hybrid feedstock is used in a large-scale application.

A Simple Method to Determine the Fractions of Labile and Mineral-Bound Microelements in Bone Tissue by Atomic Absorption Spectrometry.

In this work a simple and inexpensive method to assess the concentration ratio of the labile and mineral-bound microelements of the bone tissue was developed. The approach is based on the separation of the components of bone tissue by their selective solubility with the subsequent determination of microelements with atomic absorption spectrometry. The total concentrations of Mg, Zn, Fe, Sr, Al, Cu, and Mn and the concentrations of these elements in aqueous solutions with pH 6.5, 10, and 12 after their ultrasonically activated interaction with the powder of dried bone were determined. Two quite different bone samples were analyzed: a cortical fragment of the femur of a mature healthy cow and the spongy part of a human femoral head affected by osteoporosis. Some common and individual features of the both type of bones in regard to the total concentrations and fractional distribution of microelements are discussed. The obtained concentrations of the "soluble" fractions of microelements were critically analyzed taking into account the possible reactions leading to new insoluble phases' formation in alkaline solutions. Based on the data obtained, the ability of elements to form labile fractions in the bone tissue could be arranged in the following descending series: Mg ≥ Zn > Al > Fe > Mn > Cu > Sr.

Determination of Labile and Structurally Bound Trace Elements of Bone Tissue by Atomic Absorption Spectrometry

A method of chemical separation of the components of bone tissue, based on their selective solubility, with the subsequent determination of trace elements by atomic absorption spectrometry, is proposed. The total concentrations of Mg, Zn, Fe, Sr, Cu, Mn, and Pb, and the concentrations of these elements in solutions with pH 6.5, 10, and 12 after their interaction with the bone preparation were determined. The obtained concentrations of the “soluble” fractions of trace elements are critically analyzed taking into account the possible reactions of formation and precipitation in alkaline solutions of new insoluble phases. Based on the obtained data, the ability of elements to form mobile fractions in the composition of bone tissue can be represented as follows: Mg > Zn ≥ Fe > Sr > Cu. At the same time, noncrystalline Mg is predominantly localized in water or biological liquids of the bone, and noncrystalline Zn — in the alkali-soluble organic component of the bone. Pb and Mn are practically not detected in solutions, i.e., localized in the crystalline phase.

Sodium reduction and flavor enhancers addition: is there an impact on the availability of minerals from probiotic Prato cheese?

The effect of partial substitution of NaCl with KCl and the flavor enhancers addition (arginine, yeast and oregano extract) on the bioaccessibility of five minerals (Mg, Ca, K, P and Zn) from potentially Probiotic Prato cheese was evaluated. After 1, 30, and 60 d of refrigerated storage (processing, ripening and refrigerated storage), total concentrations of Mg, Ca, K, P and Zn were determined by flame atomic absorption spectrometry (FAAS). In addition, bioaccessibility assay with a simulated (in vitro) gastrointestinal digestion model was used. Sodium reduction and the addition of flavor enhancers revealed some significant (p < 0.05) changes in the chemical composition and pH of potentially Probiotic Prato cheese. Overall, P was the least-available element (∼4.8%). The mean availability of Mg, Ca, K and Zn was significantly ∼42.4%, 12.7%, 10.9%, and 9.2%, respectively. Na reduction and addition of flavors enhancers increased the bioaccessibility of Mg (∼6.4%), Ca (∼2.5%), K (∼4.5%), Zn (∼6.0%) and P (∼2.5%). The in vitro method supports accurate determination of the effect of the sodium reduction and addition of flavor enhancers on availability of mineral compounds ingested from potentially probiotic Prato cheese during processing, ripening and refrigerated storage.

Direct Determination of the Total Concentrations of Magnesium, Calcium, Manganese, and Iron in Addition to their Chemical and Physical Fractions in Dark Honeys

The present work demonstrates a very simple and rapid method for the reliable determination of total concentrations of Mg, Ca, Mn, and Fe in dark honeys by means of flame atomic absorption spectrometry without any special sample pretreatment except for dissolution in water. An analytical scheme for the partitioning of Mg, Ca, Mn, and Fe in analyzed honeys was proposed as well. For a complementary evaluation of fractionation patterns for studied metals, a two linked column solid phase extraction procedure with a nonionic adsorbing resin Amberlite XAD-16 and a strong cation exchange resin Dowex 50 W × 8–200 in addition to an ultrafiltration procedure with five membranes having molecular weight cut-offs of 5, 10, 30, 50, and 100 kDa were used. In the course of the fractionation analysis, it was found that the most dominant group of species is the one containing cationic forms of metals bound to low molecular weight (<5 kDa, 5–10 kDa) natural honey bioligands and is mostly the case of simple ions and labile species of Mg, Ca, Mn, and Fe. Correspondingly, the contribution of the cationic fraction for these metals in analyzed dark honeys was up to 96% (Mg), 95% (Ca), 90% (Mn), and 86% (Fe). A significant contribution of the hydrophobic fraction was also established; it was maximally 10, 18, 20, and 25% for Mg, Ca, Mn, and Fe, respectively.

P2-221: Daytime hypersomnolence on the multiple sleep latency test in patients with dementia with Lewy bodies

ods: CSF and plasma were gathered from 29 patients with DLB, 174 with AD and 90 with AD with minor vascular components. All patients who had completed a full investigation were selected consecutively from patients referred to a specialist clinic. In addition, cerebrospinal fluid and plasma were gathered from 51 healthy volunteers. Total concentrations of Mg, Ca, Mn, Fe, Cu, Zn, Rb, Sr, and Cs in cerebrospinal fluid and plasma were determined for all subjects. Results: Patients with DLB had significantly increased calcium and magnesium levels in their CSF compared to all other investigated groups (p 0.001). Mn, Fe, Cu, Zn, Cu, Rb , and Sr concentration in CSF did not differ between DLB patients and the other groups. Furthermore, a combination of CSF-Mg and CSF-Ca could distinguish DLB from AD with a sensitivity of 93% and a specificity of 85%. Cu levels in both CSF and plasma and Ca levels in plasma tended to be higher in DLB compared with the other groups, but these trends failed to reach significance after correction for multiple comparisons. Conclusions: The increased Ca and Mg concentrations in the CSF of DLB patients may be an important factor in the pathogenesis of DLB. Furthermore, determination of CSF-Mg and CSF-Ca concentration may be a valuable tool in distinguishing DLB from AD.

CSF Mg and Ca as diagnostic markers for dementia with Lewy bodies

Accumulating evidence implicates a role for altered metal homeostasis in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). However, few investigations have addressed this issue in dementia with Lewy bodies (DLB). The aim of the present study was to investigate metal concentrations in cerebrospinal fluid (CSF) and plasma from patients with DLB and other neurodegenerative disorders. To that end, CSF and plasma samples were collected from 29 patients with DLB, 174 patients with AD, 90 patients with AD with minor vascular components, and 51 healthy volunteers. Total concentrations of Mg, Ca, Mn, Fe, Cu, Zn, Rb, Sr, and Cs were determined using mass spectrometry. Patients with DLB had elevated Ca and Mg levels in CSF and Mg levels in plasma as compared to all other groups ( p < 0.001). Furthermore, a combination of CSF-Mg and CSF-Ca could distinguish DLB from AD with a sensitivity of 93% and a specificity of 85%. Cu levels in both CSF and plasma tended to be higher in DLB compared to the other groups, but these trends failed to reach significance after correction for multiple comparisons. Mn, Fe, Zn, Rb, and Sr concentration in CSF or plasma were similar in all groups. The observed elevations of CSF-Mg, CSF-Ca and CSF-Cu may contribute to or be associated with the neurodegenerative process in DLB. Furthermore, determination of CSF-Mg and CSF-Ca concentration may be a valuable tool in distinguishing DLB from AD.

Characteristics, and carbon and nitrogen dynamics in soil irrigated with wastewater for different lengths of time.

Irrigation of agricultural land with wastewater will increase crop production, but also heavy metal concentrations and the rate of infection of farmers with pathogens. The risks associated with the use of wastewater are reduced by treating the wastewater, but treatment also reduces organic material, phosphorus and inorganic N for crops. We investigated characteristics, e.g. heavy metal concentrations, of soils of the valley of the Mezquital (Mexico) irrigated with waste from Mexico City water since 1912, 1925, 1965, 1976, 1996 or 1997, or not irrigated at all, and dynamics of C and N when soil was amended with wastewater or drainage water. Concentrations of total Mg, Hg, Mo, Ca, Cu and Cr, available concentrations of Pb, Cd and Cu increased significantly with length of irrigation (P < 0.05), but were not at hazardous concentrations. Although organic C, total N, microbial biomass C and N, and microbial activity, as witnessed by CO2 production, increased with length of irrigation, N mineralization did not. Oxidation of NO2- was inhibited and could be due to increases in salinity, toxic compounds or heavy metals. We found that N mineralization was low or absent so it will not compensate for the loss of N when the wastewater is treated and application of N fertilizer will be required to maintain the same level of crop production. The characteristics of the soils appear not to have deteriorated after years of application of wastewater, but further irrigation even with treated wastewater might increase sodicity and salinity and pose a threat to future crop production.

The rapid assessment of concentrations and solid phase associations of macro- and micronutrients in alkaline soils by mid-infrared diffuse reflectance spectroscopy

Chemical analysis is a crucial but often expensive and time consuming step in the characterisation of soils. Mid-infrared diffuse reflectance (MIR-DRIFT) spectroscopy coupled with partial least square (PLS) analysis was used to determine macro- and micronutrient concentrations of a range of alkaline soils from southern Australia. Solid phase associations of macro- and micronutrients were also investigated using the mineralogical information contained in the infrared spectra of soil samples. Results showed that MIR-PLS analysis is a powerful and rapid technique for the accurate prediction of more than 15 chemical properties from each soil sample spectrum. Correlation coefficients for MIR derived concentration versus laboratory determined values were greater than R2 = 0.80 for soil moisture, calcium carbonate concentration, total concentration of Mg, K, S, Fe, Al, Mn, Zn, Cu, and oxalate- extractable Al, Fe, Mn, and Si. In calcareous soils, sulfur was associated with carbonate and conversely Mg was more related to the clay concentration of soils. Micronutrients such as Fe, Zn, Mn, and Cu were positively associated with smectite/illite in the clay fraction and negatively with kaolinite. The potential use of these results in partitioning model to assess plant available micronutrients pools is discussed.

Abnormal magnesium status in patients with cardiovascular diseases

To investigate magnesium status in patients with cardiovascular diseases and in those presenting high factors for these diseases, we measured the concentrations of serum total Mg, serum ionized Mg and intra-erythrocyte Mg. Mg is an important cofactor for many enzymes, especially those involved in phosphate transfer reactions. Mg deficiency has been shown to be associated with fatal cardiovascular diseases, as well as with risk factors for these diseases. Only measurement of the serum concentration of total Mg is routinely available, but ionized Mg is the physiologically active component. Furthermore, most of the body's Mg is present in the intracellular space. Subjects included patients with ischaemic heart disease (n=80), cardiac arrhythmia (n=60), diabetes mellitus (n=36), essential hypertension (n=194) and hypercholesterolaemia (n=60). The same measurements were made in healthy controls (30 men and 26 women; mean age 58+/-11 years). The serum ionized Mg concentration was measured with a selective ion electrode. The intra-erythrocyte Mg concentration was measured by atomic absorption. No gender difference was found for any Mg parameter, nor was age related to any Mg parameter. The serum albumin concentration was positively correlated only with the serum total Mg concentration. Although the serum total Mg concentration was similar in all groups, patients with diabetes mellitus and arrhythmia had lower serum levels of ionized Mg. Patients with essential hypertension exhibited higher intra-erythrocyte Mg concentrations than the healthy controls. Thus the measurement of serum total Mg concentration may obscure the presence of extracellular Mg deficiency in patients with arrhythmia and diabetes mellitus. Furthermore, the intracellular accumulation of Mg does not support the hypothesis of Mg deficiency in patients with essential hypertension.

Abnormal magnesium status in patients with cardiovascular diseases

To investigate magnesium status in patients with cardiovascular diseases and in those presenting high factors for these diseases, we measured the concentrations of serum total Mg, serum ionized Mg and intra-erythrocyte Mg. Mg is an important cofactor for many enzymes, especially those involved in phosphate transfer reactions. Mg deficiency has been shown to be associated with fatal cardiovascular diseases, as well as with risk factors for these diseases. Only measurement of the serum concentration of total Mg is routinely available, but ionized Mg is the physiologically active component. Furthermore, most of the body's Mg is present in the intracellular space. Subjects included patients with ischaemic heart disease (n = 80), cardiac arrhythmia (n = 60), diabetes mellitus (n = 36), essential hypertension (n = 194) and hypercholesterolaemia (n = 60). The same measurements were made in healthy controls (30 men and 26 women; mean age 58±11 years). The serum ionized Mg concentration was measured with a selective ion electrode. The intra-erythrocyte Mg concentration was measured by atomic absorption. No gender difference was found for any Mg parameter, nor was age related to any Mg parameter. The serum albumin concentration was positively correlated only with the serum total Mg concentration. Although the serum total Mg concentration was similar in all groups, patients with diabetes mellitus and arrhythmia had lower serum levels of ionized Mg. Patients with essential hypertension exhibited higher intra-erythrocyte Mg concentrations than the healthy controls. Thus the measurement of serum total Mg concentration may obscure the presence of extracellular Mg deficiency in patients with arrhythmia and diabetes mellitus. Furthermore, the intracellular accumulation of Mg does not support the hypothesis of Mg deficiency in patients with essential hypertension.

The two inverse pathways: the apoptosis and the multinucleated cell switched by the magnesium/zinc balance in irradiated Sarcoma in vivo

The Mg dependence on apoptosis, and the Zn dependence on the multinucleated cell were evaluated in irradiated Sarcoma-180 in vivo in BALB/c mice. The kinetics of total concentration of Mg strongly correlated with the frequency of apoptosis from 6 to 24 h after irradiation and that of Zn strongly correlated with the frequency of the multinucleated cell from 12 to 48 h after irradiation under the 10 or 20 Gy irradiation. There was an inverse proportion of frequency of apoptosis to that of the multinucleated cell. The administration of Mg significantly increased the frequency of apoptosis and significantly decreased the frequency of the multinucleated cell, from 6 to 12 h after the 20 Gy irradiation. In contrast, the administration of Zn significantly increased the frequency of the multinucleated cell and significantly decreased the frequency of apoptosis from 6 to 12 h under the 20 Gy irradiation. The combined administration of Mg and Zn did not change the frequency of apoptosis and the multinucleated cell. The administration of these elements did not change those correlation coefficients. The two inverse pathways were considered: the one for apoptosis; and another for the multinuclear cell, switched by the Mg/Zn balance.

THE EFFECTS OF ADDITIONS OF CaCO3 AND P ON THE SOIL SOLUTION CHEMISTRY OF A PODZOLIC SOIL

The surface horizon from a Humo-Ferric Podzol was amended with both CaCO3, and P to investigate the changes in the ionic composition of the soil solution and the charge characteristics of the horizon. Addition of CaCO3 increased the concentrations of Ca and [Formula: see text] and decreased the total concentrations of Mg, Na, K, Al, Zn, Mn, Si and [Formula: see text] in the soil solutions. In addition, the pH of the soil solutions, the content of negatively charged sites on the soil surfaces, the relative proportion of Mn2+ and Zn2+ of sulfate ion pairs were raised. In contrast, the concentrations of exchangeable Zn and Mn, the amount of positively charged sites and the proportion of metals linked with the "modelled" fulvate ligands were reduced. The addition of increasing rates of P reduced the total concentrations of Mg, K, Al, Si, and the concentrations of [Formula: see text] and [Formula: see text] in solution but did not affect the pH or the CEC of the soils appreciably. The concentrations of Si, phosphate-P, [Formula: see text] and of the sulfate ion pairs in solution were increased by increasing P additions to the soil. Key words: Liming, phosphorus fertilization, soil solution, GEOCHEM, ion speciation

ATP sulfurylase-dependent assays for inorganic pyrophosphate: Applications to determining the equilibrium constant and reverse direction kinetics of the pyrophosphatase reaction, magnesium binding to orthophosphate, and unknown concentrations of pyrophosphate

A continuous, coupled, spectrophotometric assay is described in which the enzyme ATP sulfurylase is employed to measure the concentration of inorganic pyrophosphate ( PP i ) at equilibrium with known concentrations of inorganic orthophosphate ( P i ) in the presence of excess inorganic pyrophosphatase ( PP itase). In agreement with previous reports, the apparent equilibrium constant ( K eq,app) of the PP i hydrolysis reaction was shown to decrease as the concentration of Mg 2+ is increased. At pH 7.3, 30°C, in the presence of 150 m m NaCl and 1 m m free Mg 2+, K eq,app (calculated as [ P i ] t 2 [ PP i ] t ) was 1950. Measurements of K eq,app at different total concentrations of Mg 2+ and P i permitted the determination of K 0, the dissociation constant of the Mg- P i complex. In 0.05 m Tris-Cl, pH 8.0, at 30°C, K 0 was 3.6 m m. In the presence of excess ATP sulfurylase, yeast PP itase catalyzed PP i formation from P i with a specific activity ( V max) of 9 units × mg protein −1 at pH 8.0, 30°C, and 1 m m free Mg 2+. Half-maximum reverse reaction velocity was observed at a total P i concentration of 18 m m. (Under the same conditions, V max of the PP i hydrolysis reaction was 530 units × mg protein −1.) A radiochemical end point (“reaction-to-completion”) assay for measuring unknown concentrations of PP i was devised. In the presence of excess 35 S-adenosine-5′-phosphosulfate ([ 35S]APS) as the cosubstrate, 35SO 4 2− formation was stoichiometric with added PP i. (The 35SO 4 2− and [ 35S]APS are separated by adsorption of the latter onto charcoal.) The sensitivity of the assay can be adjusted by varying the specific radioactivity of the [ 35S]APS. In the absence of interfering substances, as little as 2 pmol of PP i per 1.0 ml assay volume can be measured. The sensitivity of the assay is reduced in the presence of ATP plus perchlorate (which synergistically inhibit the enzyme). However, if the bulk of the ATP is removed from perchloric acid extracts of tissues with glucose and hexokinase, initial intracellular levels as low as 1 μ m can be measured. The possibility that most of the cellular PP i extracted with perchloric acid was originally enzyme bound is discussed.

Kinetic studies of asparagine synthetase from rat liver: Role of Mg 2+ in enzyme catalysis

The kinetic mechanism of asparagine synthetase from rat liver has been studied. The mechanism of the reaction in the presence of high concentrations of total Mg 2+ (50 m m) was suggested to be a uni-uni-bi-ter ping-pong-type without abortive complexes; glutamine binds first followed by glutamate release, and aspartate and ATP bind in order followed by ordered release of PP i AMP, and asparagine. But, it is indicated that in the presence of 0.5–2.0 m m excess Mg 2+ over ATP the binding of substrates after the release of glutamate is in a rapid equilibrium system such as ordered Mg 2+ and random aspartate-MgATP. Mg 2+ was demonstrated to have two roles in the catalysis; to modify the enzyme and to form a complex of MgATP.

The distribution of macronutrients in a broad leaf woody savanna

Early work at Nylsvley, the study site of the South African Savanna Ecosystem Project, showed a low soil nutrient status. On the basis of this and in view of the low vegetation biomass compared to other similar ecosystems, it was suggested that nutrients may be limiting productivity in this Burkea africana dominated savanna. This study examined concentrations of total, ammonium and nitrate nitrogen in Burkea savanna (Hutton form, Chester series) soils with respect to depth and time of year. It further examined the concentrations of total Mg, K and P in the soil with respect to depth. The three major tree species, B. africana, Ochna pulchra and Terminalia sericea and the two dominant grasses, Digitaria eriantha and Eragrostis pallens were examined and N, Mg, K, P and S concentrations were determined in various components of each of these species. Results obtained for the three nitrogen forms in the soil showed spatial and a considerable temporal variation. The spatial variation can partly be ascribed to tree canopies and faunal disturbance. The considerable temporal variation can not be accounted for. From the low amount of Mg and K in vegetation relative to that in the soil, it was concluded that these nutrients are unlikely to be limiting. The data for P and S are insufficient to assess their possible limitation to productivity. The possibility that nitrogen may be a factor limiting productivity is discussed. Vroeë werk op die Nylsvley studieterrein van die Suid-Afrikaanse Savanne Ekosisteemprojek, het ’n lae grondvoedingstofkonsentrasie ge-toon. Met die oog hierop en die lae plantbiomassa van die gebied relatief tot ander soortgelyke ekosisteme, is voorgestel dat die produktiwiteit van hierdie savanne wat deur Burkea africana oorheers word, deur die voedingstofstatus van die grond beperk word. In hierdie studie is die totale-, ammoniak- en nitraatstikstofkonsen-trasie van Burkea savanne grond (Hutton Chester) ten opsigte van diepte sowel as die tyd van jaar ondersoek. Die totale Mg-, K- en P- konsentrasies in die grond ten opsigte van diepte is ook bepaal. N-, Mg-, K-, P- en S-konsentrasies is ook in die verskillende onderdele van die drie hoof boomsoorte, naamlik B. africana, Ochna pulchra en Terminalia sericea sowel as die twee hoof grassoorte, Digitaria eriantha en Eragrostis pallens ondersoek. Resultate vir die drie stikstofvorms in die grond het ’n ruimtelike variasie sowel as ’n aansienlike variasie met tyd getoon. Die ruimtelike variasie kan gedeeltelik deur kroonbedekking sowel as deur dierversteuring verklaar word. Die tydsgebonde variasie is onverklaarbaar. Die verhouding van die Mg- en K-inhoud van die plante tot dié van die grond is laag. Hieruit word afgelei dat dit onwaarskynlik is dat hierdie voedingstowwe beperkend is. Die gegewens vir P en S is onvoldoende om hulle moontlike beperkende invloed op produktiwiteit vas te stel. Die moontlikheid dat stikstof produktiwiteit beperk, word bespreek.