我国部分省份（地区）汉族人群HLA-I类基因多态性地区差异分析

目的探讨我国部分省份（地区）汉族人群HLA-I类经典基因座位HLA-A、HLA-B、HLA-Cw位点的群体遗传学特点及其基因频率分布的地区差异。方法选取1014例无关汉族拟行造血干细胞移植治疗患者及其健康家系供者的血液样本,提取基因组DNA后,采用序列特异性引物聚合酶链式反应（PCR-SSP）分型技术进行HLA-A、HLA-B、HLA-Cw位点基因分型,分析不同地区汉族人群及不同种族间的基因频率分布特征。基于文献报道的我国不同地区汉族人群及不同种族的HLA-I类基因频率资料,计算种群间遗传距离（D）,比较不同地区汉族人群及不同种族间遗传距离差异。结果Hard-Weinberg吻合度检验表明,本研究抽样群体适于进行遗传学统计分析。HLA-A位点共检测出14种基因型,最常见的是A^＊02（0.330）、A^＊11（0.240）、A^＊24（0.155）、A^＊33（0.075）;HLA-B位点共检测出27种基因型,最常见的是B^＊13（0.134）、B^＊15（0.143）、B^＊40（0.133）、B^＊46（0.102）;HLA-Cw位点共检测出13种基因型,最常见的是Cw^＊01（0.157）、Cw^＊03（0.247）、Cw^＊07（0.181）、Cw^＊08（0.106）。群体汉族与其他人种间HLA-A、HLA-B基因频率差异均有统计学意义（P〈0.05）;除兰州汉族人群仅同南方汉族、湖南、山东、江苏、台湾汉族人群间HLA-A、HLA-B基因频率差异有统计学意义（P〈0.05）外,其余各地区汉族人群间HLA-A、HLA-B基因频率差异均有统计学意义（P〈0.05）。各地区汉族人群间平均遗传距离D=0.164,辽宁和北方汉族人群间遗传距离（D=0.064）最小,江苏与湖南汉族人群间遗传距离（D=0.299）最大;不同地区汉族人群间遗传距离普遍小于种族间遗传距离。结论我国不同地区汉族人群HLA-I类基因频率分布存在显著差异,但其差异要明显小于世界不同人种间的分布差异。我国汉族人群所特有的HLA-I类基因频率分布格局资料对区域性疾?     

pH effects on measurements of ionized calcium and ionized magnesium in blood

CONTEXT: It is well known that the concentration of ionized calcium in blood is affected by the pH of the specimen, since hydrogen ions compete with calcium for binding sites on albumin and other proteins. However, the relationship between pH and ionized magnesium concentration is not as well characterized. OBJECTIVE: To determine the effects of pH on ionized magnesium concentration over a wide range of pH values in serum or plasma. DESIGN: Both ionized calcium and ionized magnesium concentrations were measured in 3 sets of samples. (1) Pools of serum or whole blood at different pH values (7.20-7.60) achieved by adding a constant volume of acid or base (diluted solutions of either hydrochloric acid or sodium hydroxide) plus saline. These pools consisted of 2 serum and 3 heparinized whole blood pools collected from leftover blood remaining in clinical specimens in the Clinical Chemistry and Blood Gas Laboratories, respectively, at Duke University Medical Center. (2) Five whole blood specimens obtained from apparently healthy individual donors. (3) Twenty-six whole blood specimens obtained from individual patients (leftover blood from the Blood Gas Laboratory) in which pH was varied by in vitro loss or gain of carbon dioxide. RESULTS: Both ionized calcium and ionized magnesium concentrations decreased as the pH in the specimen increased, indicating the stronger binding of these ions with proteins in the more alkaline environment. CONCLUSION: We conclude that the rate of change of ionized magnesium concentration with pH change (0.12 mmol/L per pH unit) is significantly less than that of ionized calcium (0.36 mmol/L per pH unit). Furthermore, our findings indicate that if adjustment to pH 7.40 is necessary, the ionized magnesium test results need to be adjusted when pH is markedly abnormal, as is sometimes done for ionized calcium.     

不同工艺人血白蛋白与地西泮结合功能的比较研究

目的研究比较不同生产工艺制备的人血白蛋白（HSA）与地西泮的结合功能。方法在0.1mol/L的地西泮储备液中加入PBS缓冲液,并调整地西泮的终浓度分别为5.0、10.0、15.0、20.0、25.0μmol/L,用可见-紫外分光光度计于波长254nm处测定各样品的吸光度（A）值并绘制标准曲线。取预处理后的各HSA样品（0.615mmol/L）,分别加入终浓度为0.1、0.2、0.3、0.4、0.5mmol/L的地西泮储备液,采用超滤离心法测定超滤透析液中游离地西泮浓度,据此参照公式计算在地西泮浓度为0.1mmol/L时HSA与地西泮的结合率,以及各HSA样品与地西泮之间的结合常数。结果标准曲线显示地西泮浓度与A254值呈线性关系。各HSA样品与地西泮结合率的检测结果显示,HSA与地西泮的结合率最高为98.18%,最低为97.47%,不同生产工艺制备的样品间比较,HSA与地西泮的结合功能差异均无统计学意义。各HSA样品结合常数范围在6×104～10×10^4mol^-1之间,国内不同生产工艺制备的各HSA样品的结合常数平均值约为9.00×10^4mol^-1,与国外HSA样品（8.91×10^4mol^-1）比较差异无统计学意义,其中采用Cohn’s改良法（离心）制备的样品结合常数平均值最低（7.78×10^4mol^-1）,采用Cohn’s经典法（压滤）制备的样品结合常数平均值最高（9.57×10^4mol^-1）,生产工艺对于HSA的结合常数没有明显影响。结论不同生产工艺制备的HSA与地西泮的结合功能基本一致。     

Liquid heparin anticoagulant produces more negative bias in the determination of ionized magnesium than ionized calcium

The ionized calcium level in blood is known to be falsely decreased when self-prepared liquid heparin anticoagulant is used, due to dilution and binding effects. The effect of liquid heparin on the determination of ionized magnesium is not as well understood. We compared the effect of liquid sodium heparin on the determination of ionized calcium and magnesium in 44 clinical samples using two types of user-prepared heparin syringes which differed in the amount of residual heparin from the BD Preset reference syringe. With the type 1 syringe, the liquid heparin was expelled once or twice such that some heparin could be left in the dead space at the syringe hub, while the liquid sodium heparin was thoroughly expelled from the type 2 syringe. The ionized magnesium levels obtained with the type 1 syringe were significantly lower than the reference value (by 0.068 mmol/L) (p < 0.0001), while the value obtained with the type 2 syringe differed less from the reference, by only 0.014 mmol/L (p < 0.0001). The heparin binding effect resulted in more negative bias in ionized magnesium (- 0.026 +/- 0.032 mmol/L) than in ionized calcium (- 0.009 +/- 0.042 mmol/L, p < 0.0001). In conclusion, we recommend using lyophilized, calcium-balanced, heparinized syringes for the determination of ionized magnesium and ionized calcium due to the increased negative bias in ionized magnesium determinations. When user-prepared syringes are used, the thorough evacuation of heparin solution should be strictly prescribed.     

Early-onset increased calcium and decreased magnesium concentrations and an increased calcium/magnesium ratio in SHR versus WKY.

Alterations in the metabolism of calcium and magnesium have been implicated in the pathogenesis of primary hypertension. Calcium influx across the external cellular membrane in smooth muscle cells and cardiomyocytes plays a crucial role in the control of cellular excitation contraction and impulse propagation. Intracellular calcium and magnesium concentrations are controlled by reversible binding to specific calcium binding proteins. The calcium and magnesium flux across the external membrane is regulated by a calcium pump (calcium-magnesium-ATPase), calcium channels and binding to the membrane. In cell membranes and in lymphocytes of essential hypertensives, our group showed increased calcium and decreased magnesium and an increased calcium/magnesium ratio in hypertensive cells. In this context, in aortic smooth muscle cells from 13 spontaneously hypertensive rats (SHR) of the Münster strain (systolic blood pressure 188.4+/-9.8 mmHg) and 13 normotensive rats (NT, systolic blood pressure 118.5+/-7.2 mmHg) aged 9 months, the intracellular calcium and magnesium contents were measured under nearly in vivo conditions by electron-probe microanalysis. Measurements were performed in aortic cryosections 3 microm thick. The calcium content was 124.7+/-4.5* mmol/kg dry weight in SHR versus 110.3+/-4.1 mmol/kg dry weight in NT (Means+/-SD, p < 0.01), the magnesium content was 35.5+/-3.9* in SHR versus 50.1+/-4.9 mmol/kg dry weight in NT /p < 0.01). The calcium/magnesium ratio was significantly increased in SHR versus NT (3.56+/-0.39* versus 2.23+/-0.27, p < 0.01). In hypertensive one month old animals the increase in the calcium/magnesium ratio was not as pronounced as in 9 month old animals. The calcium/magnesium ratio was measured 3.3+/-0.42 in SHR (n = 8) as compared to 2.51+/-0.39 in normotensive animals (n = 8, p < 0.01). Aortic smooth muscle cells from SHR are characterized by markedly elevated intracellular calcium and decreased intracellular magnesium contents compared with normotensive cells. The increased calcium/magnesium ratio in hypertensive cells may be a pathogenetic factor for the development of arteriosclerosis and hypertension.     

Characteristics of improved NOVA magnesium ion-selective electrode: changes of ionized magnesium values and reference interval in healthy children.

Following the report of interference between the thiocyanate ion (SCN-) and NOVA's previous ion-selective electrode (ISE) for ionized magnesium (iMg2+), NOVA has developed a new ISE which eliminates the effect of SCN-. Two hundred and sixty healthy children were divided into two groups; those who had presented when using NOVA's previous ISE (group A; n = 160) and those using NOVA's new ISE (group B; n = 100). The mean iMg2+ value and the mean iMg2+ percent fraction (iMg2+/serum Mg) were significantly higher in group B than in group A (0.59 +/- 0.03 vs 0.54 +/- 0.03 mmol/L for iMg2+; p < 0.001 and 64.8 +/- 3.1 vs 58.2 +/- 4.1 per cent for iMg2+ percent fraction; p < 0.001). The mean serum SCN- level was 0.023 +/- 0.008 mmol/L in group A (n = 8) and 0.0.21 +/- 0.007 mmol/L in group B (n = 12), and was not significantly different between the two groups. The suspected change of iMg2+ value interfered by SCN- was 0.037 mmol/L in group A. The difference of iMg2+ percent fraction between two groups was higher at high serum magnesium (SMg) levels. The reference interval of iMg2+ was 0.56-0.62 mmo/L in healthy children with the NOVA's new ISE, and was constant irrespective of growth. The NOVA's previous iMg2+ ISE may be interfered with mainly by SCN-. The newly designed ISE eliminated these effects especially at higher SMg levels.     

Saturable binding sites mediate the entry of African swine fever virus into Vero cells

Binding experiments of 3H-labeled African swine fever virus to susceptible VERO cells have shown the presence of saturable binding sites for African swine fever virus on the plasma membrane. The Scatchard analysis of the binding data at equilibrium indicates the existence of about 10(4) cellular receptor sites per cell with a dissociation constant (Kd) of 70 pM. Virus entry into VERO cells is mediated by a saturable component, since tritiated African swine fever virus saturable binding and uptake were competed by the same amounts of unlabeled virus. Similarly, early viral protein synthesis and virus production were inhibited by concentrations of uv-inactivated virus that competed virus attachment to saturable binding sites, suggesting that specific receptors mediate the entry of African swine fever virus particles that initiate a productive infection in VERO cells. African swine fever virus binding to virus-resistant L cells was not mediated by saturable binding sites. As a result of the nonsaturable interaction the virus was not able to enter L cells and neither early viral protein synthesis nor viral DNA synthesis was detected, indicating that the absence of specific receptors for African swine fever virus is a factor that determines the resistance of L cells to the infection.     

Factors influencing the protein binding of IQO4, a new isoquinolinedione derivative

Various factors most likely to influence the plasma protein binding of IQO4, a new isoquinolinedione derivative, to 4% human serum albumin (HSA) were evaluated using an equilibrium dialysis technique at an initial IQO4 concentration of 5 microg/ml. It took approximately 12 h incubation to reach an equilibrium between 4% HSA and isotonic S?rensen phosphate buffer at pH 7.4 containing 3% dextran ('the buffer') using a Spectra/Por 2 membrane (molecular weight cut-off, 12000-14000) in a water-bath shaker kept at 37 degrees C and at a rate of 50 oscillations per min. IQO4 was stable both in 4% HSA and in 'the buffer' for up to 24 h incubation at 37 degrees C. The binding of IQO4 was constant (89.9 +/- 1.40%, mean +/- standard deviation) at IQO4 concentrations ranging from 1 to 100 microg/ml. However, the extent of binding was dependent on HSA concentrations. The values were 32.5, 62.0, 79.1, 84.9, 90.9, 91.2, and 91.7% at HSA concentrations of 0.5, 1, 2, 3, 4, 5, and 6%, respectively; on incubation temperature, 96.7, 93.8, and 91.0% when incubated at 4, 22, and 37 degrees C, respectively; and on the buffer pHs, 84.4, 87.2, 88.2, 90.9, and 92.3% for the buffer pHs of 5.8, 6.4, 7, 7.4, and 8, respectively. The free fraction of IQO4 increased with the addition of sulfisoxazole (0-300 microg/ml), and salicylic acid (0-300 microg/ml). The protein binding of IQO4 was independent of the quantity of alpha-1-acid glycoprotein (up to 0.32%), chloride ion (up to 0.546%) and heparin (up to 40 units/ml).     

Normal values for serum, ultrafilterable and intraerythrocytic magnesium in children.

Serum magnesium (MgS), levels were determined in 137 children age range 2 months to 16 years. Ultrafilterable magnesium (MgU) and intraerythrocytic magnesium (MgI) concentrations were determined in 37 of these children. MgS was 0.83 +/- 0.1 mmol/L (range 0.66-1.36 mmol/L), with no differences between sexes. Children under 2 years had higher MgS levels (0.92 +/- 0.13 mmol/L) than children over 2 years (0.81 +/- 0.08 mmol/L; p < .001). Mean MgU was 0.60 +/- 0.07 mmol/L (range 0.50-0.87 mmol/L), with no differences between sexes. Mean MgI in children was 2.58 +/- 0.33 mmol/L (range 2.06-3.6 mmol/L), with no differences between sexes. MgS correlated with MgU, age, theoretical growth rate, and serum calcium, phosphorus and alkaline phosphatase; MgU correlated with MgI, age, theoretical growth rate, and serum phosphorus. MgS concentration was higher in children under 2 years than in children over 2 years. In healthy children, MgS concentration correlated with MgU, and MgU correlated with MgI, but MgS and MgI showed no correlation.     

Towards bio monitoring of toxic (lead) and essential elements in whole blood from 1- to 72-month old children: a cross-sectional study

Objectives

Minerals such as zinc, copper, selenium, calcium, and magnesium are essential for normal human development and functioning of the body. They have been found to play important roles in immuno-physiologic functions. The study is to evaluate the distribution and correlation of nonessential (lead) and essential elements in whole blood from 1- to 72-month old children.

Methods

The cross-sectional study was performed in 1551 children. Six element concentrations, including copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), iron (Fe) and lead (Pb) in the blood were determined by atomic absorption spectrometry. Distributions and correlations of trace elements in different age groups were analyzed and compared. A Pearson correlation controlled for age and gender was used to assess the relationship of non essential (lead) and essential elements.

Results

Levels of copper and magnesium were 18.09 ± 4.42 µmol/L and 1.42 ± 0.12 mmol/L, respectively. 6.04% of all children showed copper levels below the normal threshold, the levels of Magnesium were stable in different age groups. Though the overall mean blood zinc and iron concentrations (61.19 ± 11.30 µmol/L and 8.24 ± 0.59 mmol/L, respectively) gradually increased with age and the overall deficiency levels (24.1% and 36.0%, respectively) decreased with age, zinc and iron deficiencies were still very stable. Controlling for gender and age, significant positive correlations were found when comparing copper to zinc, calcium, magnesium, and iron ((r = 0.333, 0.241, 0.417, 0.314 ,p < 0.01); zinc to magnesium and iron (r = 0.440, 0.497p < 0.01); and magnesium to Calcium and iron (r = 0.349, 0.645, p < 0.01). The overall mean blood lead levels (41.16 ± 16.10) were relatively unstable among different age groups. The prevalence of lead intoxication in all children was 1.3% .Calcium levels decreased gradually with age, with an overall concentration of 1.78 ± 0.13 mmol/L.

Conclusion

Significant negative correlations were also noted between Pb and Zn, Fe (r = −0.179, −0.124.p < 0.01) .The importance of calcium deficiency and supplementation is well realized, but the severity of iron and zinc deficiency is not well recorded. The degree of lead intoxication in all the children studied was low; The established reference intervals for Cu, Zn, Ca and Mg provide an important guidance for the reasonable supplementation of essential elements during different age groups.     

Specific binding of [3H]inositol trisphosphate to rat cerebral cortical microsomal membranes

Specific binding sites for inositol-(1,4,5)-trisphosphate (IP3) were demonstrated in rat cerebral cortical microsomal membranes using [3H]IP3 as the ligand. The binding was displaceable (IC50 for IP3 = 28 nM), high affinity (Kd = 20 nM) and saturable (Bmax = 7.75 pmol/mg protein). Kinetic studies showed an extremely rapid time-course of [3H]IP3 binding with half-maximal binding achieved in less than 1 min and equilibrium binding was attained by around 5 min. These results are in accord with the proposed function of IP3 in mobilizing intracellular calcium from endoplasmic reticulum.     

Amounts and distribution of intracellular magnesium and calcium in pancreatic β-cells

β-Cell-rich pancreatic islets were incubated for 60–120 min in the presence of 1 mM or 20 mM glucose and analysed with regard to their contents of magnesium and calcium and how these elements were distributed among subcellular fractions. The islets contained 42 mmol magnesium per kg protein with as much as 70 mmol per kg protein in the microsomal fraction. Both the total amount and intracellular distribution of magnesium remained unaffected after raising the glucose concentration of the incubation medium. The islet content of calcium was twice as high as that of magnesium, the mitochondria and secretory granules accounting for most of the calcium in the sedimentable fractions. In both organelles a substantial fraction of calcium was exchangeable as indicated from the incorporation of ⁴⁵Ca during 90 min of incubation of the islets. When raising the glucose concentration to 20 mM the percentage exchange of calcium increased from 10 to 27 in the mitochondria and from 13 to 28 in the secretory granules. The glucose stimulation of ⁴⁵Ca uptake was not associated with a statistically significant increase in the total amounts of calcium. However, in addition to stimulating calciumkalcium exchange, it cannot be excluded that glucose also induces a net accmulation of intracellular calcium in the β-cells.     

Blood plasma and saliva levels of magnesium and other bivalent cations in patients with parotid gland tumors.

The plasma and saliva cations in parotid malignant tumors of stages II-III were studied in 31 patients before surgical therapy and in 27 control group volunteers. The magnesium (t-Mg), calcium (t-Ca), copper (t-Cu) and zinc (t-Zn) concentrations in plasma were determined, and t-Mg and t-Ca in saliva. Our results showed that salivary and plasma t-Mg concentrations were significantly higher in patients with parotid malignant tumors in comparison to control group (saliva: 0.25 +/- 0.04 mmol/L versus 0.14 +/- 0.03/L, p < 0.01; plasma: 1.05 +/- 0.06 mmol/L versus 0.86 +/- 0.05 mmol/L, p < 0.05). The t-Ca plasma concentrations were lower for patients with parotid malignant tumors by 20-22% in comparison to the control group (p < 0.05). Plasma and salivary t-Mg/t-Ca molar ratios are respectively 0.38 and 0.12 for control group, and respectively 0.61 and 0.31 for patients with parotid gland tumors. The t-Zn plasma concentration for patients with parotid malignant tumors (0.017 +/- 0.010 mmol/L) was significantly lower (p < 0.05) in comparison to control group (0.024 +/- 0.011 mmol/L). Plasma t-Cu/t-Zn molar ratio is respectively 0.68 for control group and 1.12 for patients with parotid gland tumors. The mechanism responsible for the increase of salivary magnesium as a consequence of the development of tumoral tissue needs to be clarified.     

Characterisation of the binding of digitoxin and acetyldigitoxin to human serum albumin by high-performance affinity chromatography

Zonal elution and high-performance affinity chromatography were used to examine interactions of the drugs digitoxin and acetyldigitoxin with the protein human serum albumin (HSA). This was done by injecting small amounts of digitoxin and acetyldigitoxin onto an immobilized HSA column in the presence of mobile phases that contained various concentrations of digitoxin, acetyldigitoxin or other solutes as competing agents. A fixed concentration of beta-cyclodextrin was also present in the mobile phase as a solubilising agent. It was found that digitoxin and acetyldigitoxin each had strong interactions at a single common binding site on HSA, but with slightly different equilibrium constants for this region. Neither compound showed any competition with warfarin or L-tryptophan, which were used as probes for binding at the warfarin-azapropazone and indole-benzodiazepine sites of HSA. These results confirmed the presence of a separate binding region on HSA for digitoxin-related compounds.     

Evidence for a low-affinity interleukin-3 receptor

Interleukin-3 (IL-3) regulates the proliferation of myeloid, erythroid, and lymphoid cells. Previous reports showed IL-3 binding restricted to a single high-affinity (Kd = 50-200 pM) site. Here, we demonstrate by equilibrium studies an additional binding site for IL-3 with lower apparent affinity (Kd = 5-20 nM). Furthermore, kinetic analysis shows that two binding sites for IL-3 exist: IL-3 dissociates slowly from the first site (T1/2 = 4 hr; k-1 = 2.7 x 10(-3) min-1), whereas it dissociates rapidly (T1/2 = 4.0 min; k-1 = 0.116 min-1) from the second site. Cross-linking showed that [125I]IL-3 binding to the 115- and 140-kD proteins was not saturable at concentrations commensurate with high-affinity binding and IL-3 dissociated rapidly from these same molecules. Thus, the low affinity IL-3 receptor is a molecule(s) of 115- to 140-kD.     

Amounts and distribution of intracellular magnesium and calcium in pancreatic beta-cells

beta-Cell-rich pancreatic islets were incubated for 60-120 min in the presence of 1 mM or 20 mM glucose and analysed with regard to their contents of magnesium and calcium and how these elements were distributed among subcellular fractions. The islets contained 42 mmol magnesium per kg protein with as much as 70 mmol per kg protein in the microsomal fraction. Both the total amount and intracellular distribution of magnesium remained unaffected after raising the glucose concentration of the incubation medium. The islet content of calcium was twice as high as that of magnesium, the mitochondria and secretory granules accounting for most of the calcium in the sedimentable fractions. In both organelles a substantial fraction of calcium was exchangeable as indicated from the incorporation of 45Ca during 90 min of incubation of the islets. When raising the glucose concentration to 20 mM the percentage exchange of calcium increased from 10 to 27 in the mitochondria and from 13 to 28 in the secretory granules. The glucose stimulation of 45Ca uptake was not associated with a statistically significant increase in the total amounts of calcium. However, in addition to stimulating calcium/calcium exchange, it cannot be excluded that glucose also induces a net accumulation of intracellular calcium in the beta-cells.     

Derivation and internal validation of an equation for albumin-adjusted calcium

Background

Previously published equations to adjust calcium for albumin concentration may vary depending on factors such as the type of reagents used. Albumin-adjusted calcium equations derived from laboratories using the bromocresol purple (BCP) albumin binding reagent have not been described.

Methods

The linear regression equation for the binding of calcium and BCP-albumin was derived in a cohort of 4613 outpatients, and the albumin-adjusted calcium equation was internally validated in a separate cohort of 1538 subjects. The performance of this equation was compared with a previously published equation (adjusted [Ca](mmol/L) = total [Ca](mmol/L) + 0.02 (40 - [albumin] (g/L)) in 343 subjects with albumin < 33 g/L (below reference range).

Results

The local adjustment equation was expressed by the relationship; adjusted [Ca](mmol/L) = total [Ca](mmol/L) + 0.012 (39.9 - [albumin](g/L)). The equation showed evidence of good internal validity (shrinkage value of adjusted r² = -0.0059). Classification of calcium status differed between the two equations in 47 of 343 subjects with low serum albumin (weighted κ = 0.46; moderate agreement).

Conclusion

A locally derived and internally validated albumin-adjusted calcium equation differed from previously published equations and resulted in important differences in classification of calcium status in hypoalbuminemia patients. Individual laboratories should determine their own linear regression equation for calcium on albumin rather than relying on published formulas.     

Serum magnesium concentration is a significant predictor of mortality in maintenance hemodialysis patients

A few studies have reported a correlation between magnesium and co-morbidity and mortality in end-stage renal disease. We investigated the prognostic value of serum magnesium concentration for mortality in 515 patients on maintenance hemodialysis (60 +/- 12 years, 306 males and 209 females; 24% diabetics). The patients underwent follow-up for 51 +/- 17 (mean +/- SD) months, and the relationship between the baseline magnesium concentration (mean of four months) and outcomes was analyzed statistically. During the follow-up period, there were 103 all-cause deaths, including 63 non-cardiovascular deaths. Kaplan-Meier analysis revealed that mortality was significantly higher in the lower magnesium group (< 2.77 mg/dL, i.e. < 1.14 mmol/L, n = 261), compared to that in the higher magnesium group (> or = 2.77 mg/dL, n = 254) (p < 0.001). Multivariate Cox proportional hazard analysis demonstrated that serum magnesium was a significant predictor for mortality (HR [per 1 mg/dL increase], 0.485 [95% CI, 0.241-0.975], p = 0.0424), particularly for non-cardiovascular mortality (HR 0.318 [95% CI, 0.132 to 0.769], p = 0.0110), after adjustment for other confounders, such as age, gender, hemodialysis duration, and the presence of diabetes. In conclusion, it is demonstrated that lower serum magnesium level is a significant predictor for mortality in hemodialysis patients, particularly for non-cardiovascular mortality, although the mechanisms remain to be explored in future studies. Factors affecting serum magnesium concentrations should be investigated in terms of better survival, including dietary magnesium intake. Further extensive studies may be also needed for possible reconsideration of the current dialysate magnesium concentration (1.0 mEq/L, i.e. 0.50 mmol/L used in most countries), one of the strong contributors to the serum magnesium concentrations of dialysis patients.     

Hydrochloric attack of serpentinites: Mg2+ leaching from serpentinites.

This paper presents the hydrochloric attack of serpentinites. Romanian serpentinites are part of the Danubian crystalline complex. These serpentinites contain mineral serpentine (magnesium silicate) and a small amount of other minerals along with calcium, iron, aluminium, nickel, cobalt, chrome and manganese. For processing, the serpentinite was attacked by hydrochloric acid from two provinces (p.a. and residual hydrochloric acid), using different experimental conditions: acid concentrations between 15-23 per cent HCl, the temperature range of 70-90 degrees C, with stoichiometric ratio between reactants and with acid excess, the extraction time being up to 180 min. In optimum conditions, the magnesium extraction is almost total (99.5 per cent). A well-balanced processing of these serpentinites looks for both the silica residue utilization and the chloride solutions, in order to separate the prevalent magnesium as well as the valuable microcomponents--nickel and cobalt.     

The influence of magnesium supplementation on magnesium and calcium concentrations in hair of children with magnesium shortage.

46 children, aged 2-6 years, with decreased magnesium concentrations in hair, were studied. Magnesium supplementation consisted of Asmag preparation for 3 months and multivitamin Multi-tabs preparation (containing magnesium, but without calcium) for the following 4 months. Control studies were performed again after 7 months of treatment, i.e. 12 months after the initial measurements (the same season of the year--early spring). The results proved increases of both magnesium (from 7.74 microg/g dry mass to 11.03 microg/g dry mass) and calcium (from 159.82 mg/g dry mass to 191.60 mg/g dry mass) concentrations in hair. Increased magnesium concentrations were observed in 40 studied children (86.95 per cent). Post supplementation magnesium deficiency was found in 22 children (47.83 per cent), and four children (8.70 per cent) showed further worsening of hypomagnesemia. Increased calcium concentrations were found in 42 children (91.30 per cent), while decreased Ca levels were found in 4 children (8.70 percent). The achieved results indicate a positive influence of that form of compensation of magnesium deficiency, and suggest the need of individual selection of doses and period of Mg supplementation. The initial level of hypomagnesemia, presence of factors that might inhibit intestinal absorption, accompanying diseases that might cause decrease in magnesium concentration and other factors that might influence the total body magnesium concentration should be taken into account while designing the supplementation therapy.