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PubMed1980

Heparin--magnesium chloride--albumin method for enzymic measurement of cholesterol in high-density lipoprotein.

We describe a new method for measuring high-density-lipoprotein cholesterol in sera, with use of heparin, MgCl2, and albumin to precipitate very-low- and low-density lipoproteins, Lipoprotein electrophoresis and immunochemical methods show that high-density lipoprotein is completely and specifically isolated in the supernate, the cholesterol concentration of which is estimated by the enzymic method of Allain et al. (Clin. Chem. 20, 470, 1974). The precision of the method is excellent (CV = 1%) and the response is linear. Values so obtained correlate well with those obtained with the heparin-Mn2+ (r = 0.98) or the phosphotungstate-Mg2+ (r = 0.98) procedures. The technique is appropriate for routine clinical laboratory use.

Adult↗
PubMed1989

Determination of HDL2 cholesterol by precipitation with dextran sulfate and magnesium chloride: establishing optimal conditions for rat plasma.

Optimal conditions for analyzing HDL2 cholesterol in small amounts of rat plasma have been studied using different concentrations of dextran sulfate and MgCl2 to precipitate lipoproteins containing apolipoprotein B and/or apo E. When the MgCl2 level was 91 mM, the supernate cholesterol was rather constant at a level of about 50-60% of the total plasma cholesterol concentration. Immunochemical determination of the apo A-I content indicated that no major losses of the HDL2 fraction took place under these conditions. The recovery of about 96% of HDL2 lipoproteins after the precipitation of rat plasma and the almost complete absence of lipoproteins belonging to the VLDL, LDL and HDL1 fractions was demonstrated by agarose gel electrophoresis. Thus, the method should be suitable for screening the HDL2 cholesterol content in small volumes of rat plasma.

Animals↗
PubMedDate not supplied

Effect of magnesium chloride and guanidinium chloride on the extraction of components of extracellular matrix from chicken cartilage.

In order to evaluate the effect of chaotropic agents on proteoglycan and non-collagenous proteins, chicken xiphoid cartilage was treated with guanidine-HCl and MgCl2 in different concentrations (1M to 5M), and different periods of time (12, 24, 48 and 72 hr). The maximum yield of uronic acid was obtained with 3M MgCl2 (73.3%). Concentrations of 4M and 5M of MgCl2 showed that much less uronic acid was removed, 55.3% and 38.1% respectively. Extraction with 3M MgCl2 and 3M guanidine-HCl resulted better efficiency when performed for 48 hr. Analysis by SDS-PAGE of the extracts obtained with guanidine-HCl and MgCl2 in different concentrations pointed out that most components are equally removed with the two solvents, showing that the extraction with MgCl2 is an alternative assay to remove non-collagenous proteins from extracellular matrix.

Animals↗
PubMed1989

The effect of incubation temperature and magnesium chloride concentration on growth of salmonella in home-made and in commercially available dehydrated Rappaport-Vassiliadis broths.

Growth rate of salmonellas in Rappaport-Vassiliadis broth (RV) decreased with higher temperature when incubated at 40, 42 and 43 degrees C. Home-made RV and RV-Merck were less inhibitory than RV-Oxoid and RV-lab m. At 43 degrees C growth of all strains of Salmonella dublin were almost completely inhibited in all types of RV. In home-made RV and RV-Merck incubated at 42 degrees C, Salm. dublin was not inhibited any more than other serotypes tested. Variations in growth rate between different types of RV could be explained by differences in concentration of MgCl2. RV with higher MgCl2-concentration were most inhibitory. It is proposed that RV should be incubated at 41.5 +/- 0.5 degrees C (42.0 +/- 0.1 degrees C in a waterbath) and that the amount of MgCl2.6H2O should be approximately 28.6 g/l of the ready-to-use medium, which corresponds to the formula in the original description.

Culture Media↗
PubMed1989

Rapid method for the isolation of two purified subfractions of high density lipoproteins by differential dextran sulfate-magnesium chloride precipitation.

We describe a rapid and reliable three-step precipitation procedure for the isolation of large amounts of the two major components of high density lipoproteins (HDL) in human serum. Precipitation was accomplished by means of dextran sulfate (DS) of mol. wt. 500,000 and MgCl2. First, all apoB-associated lipoproteins of any density were selectively precipitated with critical concentrations of reagents. Secondly, a subfraction of HDL was differentially precipitated from the apoB-depleted serum by increasing the concentration of both reagents. Eventually, the bulk of the remainder of HDL was precipitated by lowering the pH to 5.4. According to the precipitation patterns and the density profiles, the DS-Mg procedure provides a clear differentiation between the two HDL components. According to the compositional criteria and the ultracentrifugal characteristics, the two polyanion-precipitated subclasses are very similar to, if not identical with, the two density subclasses, the lighter HDL2 and the heavier HDL3, isolated by preparative ultracentrifugation after apoB-containing lipoproteins had been removed.

Chemical Precipitation↗
PubMed1992

Differential staining of glycosaminoglycans in the predentine and dentine of rat incisor using cuprolinic blue at various magnesium chloride concentrations.

Rat incisors were fixed with a solution of 0.05% Cuprolinic Blue and 2.5% glutaraldehyde in the presence of various concentrations of MgCl2 according to the critical electrolyte concentration (CEC) principle. This method allows glycosaminoglycans (GAG) to be properly preserved and visualized. Small granules were stained by the cationic dye in the predentine in the absence of MgCl2. These granules grew in size and became more electron-dense when the concentration of the electrolyte was increased. Larger ribbon-like structures and granules were seen when 0.3 M MgCl2 was used. In the dentine, tiny dots in close association with the surface of the collagen fibres, or their periodic striations, were positively stained. A thick electron-dense band located on the dentine side at the predentine-dentine junction was seen both with and without 0.05 M MgCl2. With higher concentrations of the electrolyte (0.1-0.3 M), this band was reduced to a very thin line located at the border of the dentine, along with mineralizing collagen fibres. This demonstrated the presence of GAG at the dentine surface and therefore indicated that GAG may play a role as nucleator agent.

Animals↗
PubMed1987

Effects of magnesium chloride on the contractile response of uterus to several agonists in Ca-free solution.

The effects of MgCl2 on the oestrogen-dominated rat uterus have been examined. Tissues were preincubated in a Ca2+- and Mg2+-free medium containing 3 mM EDTA. Most experiments were subsequently performed in a similar medium containing either no EDTA or EDTA (1 mM). When MgCl2 was added cumulatively (1-32 mM) no contractile responses were obtained in Ca,Mg-free medium or in Ca,Mg-free high K+ solution. When 2 mM CaCl2 was added, a sustained contraction was obtained. Subsequent addition of cumulative concentrations of MgCl2 caused concentration-dependent relaxation. Oxytocin, 2 microM, produced a small and sustained contraction in a Ca,Mg-free medium. Addition of MgCl2, 2 mM, increased this contraction. In a Ca,Mg-free medium vanadate (8 X 10(-5)M) did not evoke spasm of uterine smooth muscle. After addition of MgCl2 in cumulative amounts (1-32 mM) in the presence of vanadate, a concentration-dependent contraction was obtained. The present work shows that in Ca-free solution, maintained contractions induced by oxytocin and vanadate are augmented by Mg2+.

Animals↗
PubMed1984

Effects of magnesium chloride on smooth muscle actomyosin adenosine-5'-triphosphatase activity, myosin conformation, and tension development in glycerinated smooth muscle fibers.

The contractile system of smooth muscle exhibits distinctive responses to varying Mg2+ concentrations in that maximum adenosine-5'-triphosphatase (ATPase) activity of actomyosin requires relatively high concentrations of Mg2+ and also that tension in skinned smooth muscle fibers can be induced in the absence of Ca2+ by high Mg2+ concentrations. We have examined the effects of MgCl2 on actomyosin ATPase activity and on tension development in skinned gizzard fibers and suggest that the MgCl2-induced changes may be correlated to shifts in myosin conformation. At low concentrations of free Mg2+ (less than or equal to 1 mM) the actin-activated ATPase activity of phosphorylated turkey gizzard myosin is reduced and is increased as the Mg2+ concentration is raised. The increase in Mg2+ (over a range of 1-10 mM added MgCl2) induces the conversion of 10S phosphorylated myosin to the 6S form, and it was found that the proportion of myosin as 10S is inversely related to the level of actin-activated ATPase activity. Activation of the actin-activated ATPase activity also occurs with dephosphorylated myosin but at higher MgCl2 concentrations, between 10 and 40 mM added MgCl2. Viscosity and fluorescence measurements indicate that increasing Mg2+ levels over this concentration range favor the formation of the 6S conformation of dephosphorylated myosin, and it is proposed that the 10S to 6S transition is a prerequisite for the observed activation of ATPase activity. With glycerinated chicken gizzard fibers high MgCl2 concentrations (6-20 mM) promote tension in the absence of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Actomyosin↗
PubMed1999

Hemodynamic and metabolic alterations associated with intravenous infusion of a combination of adenosine triphosphate and magnesium chloride in conscious horses.

OBJECTIVE: To determine hemodynamic and metabolic effects of IV infusion of ATP-MgCl2 combination and maximal safe IV infusion rate in conscious horses. ANIMALS: 6 adult female horses. PROCEDURE: All horses received an IV infusion of ATP-MgCl2 combination, beginning at a rate of 0.05 mg of ATP/kg of body weight/min, which was increased by 0.05 mg/kg/min increments at 10-minute intervals until a rate of 1.0 mg/kg/min was achieved. Data were collected prior to the start of the infusion, at the end of each infusion rate, and at 15-minute intervals for the next hour after discontinuation of the infusion. Measured or calculated hemodynamic variables included cardiac output, cardiac index, heart rate, stroke volume, systemic and pulmonary arterial pressures, and systemic and pulmonary vascular resistances. Arterial blood gas tensions, CBC, plasma biochemical profiles, urine volume and specific gravity, and selected clinical signs of disease also were evaluated. RESULTS: Intravenous infusion of ATP-MgCl2 significantly increased cardiac output, decreased systemic vascular resistance, and caused mild pulmonary hypertension. Magnitude of the hemodynamic alterations was dependent on rate of infusion. Maximal safe infusion rate for these horses was 0.3 mg/kg/min. All horses became lethargic, and their appetites diminished during the infusion; 5 horses had mild signs of abdominal discomfort. Flank sweating was observed in all horses as infusion rate increased. Urine volume and specific gravity and hematologic, biochemical, and arterial blood gas alterations were detected during and after infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous administration of ATP-MgCl2 in healthy, conscious, adult horses caused various metabolic and hemodynamic alterations that were without appreciable detrimental effects.

Adenosine Triphosphate↗
PubMed1996

Effects of ATP-magnesium chloride on the cardiopulmonary manifestations of group B streptococcal sepsis in the piglet.

Low dose ATP-MgCl2 is reported to cause selective pulmonary vasodilation during hypoxic and thromboxane mimetic-induced constriction. In addition, it has been shown to increase cardiac output and improve cellular function during circulatory shock. Based on these properties we hypothesized that ATP-MgCl2 might ameliorate the cardiopulmonary manifestations of sepsis secondary to group B streptococci (GBS). We studied 14 anesthetized, mechanically ventilated piglets who received a continuous infusion of GBS (7.5 x 10(7) colony-forming units/kg/min) and were randomly assigned to a treatment group that received a continuous infusion of ATP-MgCl2 at 0.6 mumol/kg/min or a control group that received normal saline as placebo. Comparison of the hemodynamic measurements, pulmonary mechanics, and arterial blood gases over the first 120 min of ATP-MgCl2 infusions with those of the control group revealed the following: GBS infusion caused significant increases in mean pulmonary artery pressure, pulmonary vascular resistance (PVR), mean systemic arterial blood pressure, systemic vascular pressure (SVR), and PVR/SVR ratio with decreases in cardiac output and stroke volume. ATP-MgCl2 caused significant reduction in mean pulmonary artery pressure (p < 0.001), PVR (p < 0.0001), mean systemic arterial blood pressure (p < 0.003), SVR (p < 0.01), and PVR/SVR ratio (p < 0.03) with improvement in cardiac output (p < 0.001) and stroke volume (p < 0.01). The partial pressure of arterial O2 (p < 0.04), and pH (p < 0.001) were higher and the partial pressure of arterial CO2 (p < 0.02) lower in ATP-MgCl2-treated animals. Also dynamic lung compliance was higher (p < 0.001) and pulmonary airway resistance lower (p < 0.001) in treated animals. Median survival in control animals was 153 min, whereas all treated animals survived to 240 min (p < 0.001). These data demonstrate that ATP-MgCl2 ameliorates the deleterious cardiopulmonary manifestations of GBS sepsis and results in improved survival in a young animal model.

Adenosine Triphosphate↗
PubMed1995

Acetylcholinesterase of human intestinal tissue affected by Hirschsprung's disease: effect of magnesium chloride on isoforms.

Acetylcholinesterase (AChE) molecular isoforms from anglionic and adjacent unaffected (control) colonic tissue in patients with Hirschsprung's disease (HD) were analysed by density gradient centrifugation in order to determine the major AChE isoforms and the effect of a reported MgCl2 inactivation assay method upon them, with a view to improving the AChE assay used in the diagnosis of Hirschsprung's disease. The total AChE level was greater in the HD-affected colonic tissue than the control tissue (HD: 9.0 vs. control: 7.3 units/g tissue) and this was due to a consistently greater elevation of the globular tetrameric form, G4 (HD: 48.8% vs. control: 35.5% of total AChE). The inactivation of whole tissue homogenates by brief exposure to 4 mol/l MgCl2 followed the same pattern (HD: 48.4% vs. control: 28.7% inactivation). The detergent-extractable G4 is inhibited to a greater extent than the low salt-soluble G4 by exposure to 4 mol/l MgCl2 (83.8% vs. 51.1%). These results imply that the elevated AChE levels in HD are mainly due to increases of the hydrophobic globular tetrameric form of AChE of the same type that is found in differentiating nervous tissue before synapse formation. The monomeric globular isoform G1 is not inhibited but the asymmetric A4, A8 and A12 isoforms are completely inhibited by exposure to 4 mol/l MgCl2. All isoforms of Torpedo (electric ray) electroplax and human erythrocyte AChE, mainly amphiphilic G2, are almost completely inhibited. The inhibition by 4 mol/l MgCl2 of the main G4 isoform in HD-affected intestine accentuates the difference between aganglionic and unaffected intestine in fractionated samples, but does not provide a sufficiently specific G4 isoform assay. The use of 2-4 mol/l MgCl2 in histochemical AChE staining reduces the activity slightly but does not differentiate the tetrameric AChE isoform that is increased in Hirschsprung's disease but does reduce contaminating erythrocyte AChE levels that can obscure the result in blood-stained biopsies. A specific immunochemical stain for hydrophobic AChE tetramers or the associated 20 kDa membrane associated subunit is therefore needed to provide specificity.

Acetylcholinesterase↗
PubMed1983

Cuprolinic Blue: a specific dye for single-stranded RNA in the presence of magnesium chloride. I. Fundamental aspects.

Qualitative and quantitative aspects of the cationic dye Cuprolinic Blue were investigated with model films of polyacrylamide gel in which RNA, DNA and other biological polyanionic compounds had been incorporated. In the presence of 1 M MgCl2, Curpolinic Blue was found to bind specifically to single-stranded RNA, leaving native DNA, proteins, (acid) polysaccharides and phospholipids completely unstained. Under these conditions, Cuprolinic Blue is complexed by non-electrostatic bonds with non-stacke purine bases, mainly adenine. Optimal conditions for dye binding and differentiation have been defined. Both the Cuprolinic Blue-MgCl2 staining of single-stranded RNA and the Cuprolinic Blue staining of RNA and DNA in the absence of MgCl2 were found to obey the Lambert-Beer law. The advantages and possible applications of Cuprolinic Blue are compared with well-known (indirect) histochemical RNA staining procedures.

Animals↗
PubMed1987

Method for determination of sodium, potassium, calcium, magnesium, chloride, and phosphate in the rat choroid plexus by flame atomic absorption and visible spectroscopy.

A rapid simple technique for the measurement of Na+, K+, Mg2+, Ca2+, PO4(3-), and Cl- was developed to analyze ion contents in the choroid plexus of the rat. The technique involves digestion in piperidine, precipitation of proteins with HClO4, and analysis of Na+, K+, Ca2+, and Mg2+ by atomic absorption spectroscopy and Cl- and PO4(3-) by visible spectroscopy. The coefficient of variation for the measurement of eight replicates was 1-3% for all ions. Analysis of choroid plexuses from eight rats yielded coefficients of variation of about 6% and the values for Na+, K+, and Cl- compared favorably to previous works. The analytical procedure described in this paper allows the determination of six major physiologic ions in rat choroid plexus (4 mg wet wt).

Animals↗
PubMed1978

Stabilizing effect of magnesium chloride and sucrose on Sabin live polio vaccine.

A trivalent vaccine was stabilized with (a) 70% sucrose, (b) MgCl2 1M, and (c) 35% sucrose plus MgCl2 1/2M. A portion of each batch was kept at +4 degrees C and 22-25 degrees C. No change in titre for all 3 preparations was recorded after 9 weeks storage at +4 degrees C. While the potency of vaccines containing MgCl2 alone or mixed with sucrose and kept at +25-28 degrees C for 5 weeks was not altered, the vaccine containing only sucrose was less stable, and a drop of titre was noticed after 2 weeks of storage at +22-25 degrees C. Monovalent polio vaccines were also stabilized as above and kept at +4 degrees C or at -20 degrees C. It was found that regardless of the type of stabilizer used, 82 to 97 per cent of potency was retained after 9 months of storage at +4 degrees C or at -20 degrees C.

Chlorides↗