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Nanobelt formation of magnesium hydroxide sulfate hydrate via a soft chemistry process.

J Phys Chem B Condens Matter Mater Surf Interfaces Biophys. 2006 Jul 13;110(27):13387-92

Authors: Zhou Z, Sun Q, Hu Z, Deng Y

The nanobelt formation of magnesium hydroxide sulfate hydrate (MHSH) via a soft chemistry approach using carbonate salt and magnesium sulfate as reactants was successfully demonstrated. X-ray diffraction (XRD), energy dispersion X-ray spectra (EDS), selected area electron diffraction (SAED), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis revealed that the MHSH nanobelts possessed a thin belt structure (approximately 50 nm in thickness) and a rectangular cross profile (approximately 200 nm in width). The MHSH nanobelts suffered decomposition under electron beam irradiation during TEM observation and formed MgO with the pristine nanobelt morphology preserved. The formation process of the MHSH nanobelts was studied by tracking the morphology of the MHSH nanobelts during the reaction. A possible chemical reaction mechanism is proposed.

PMID: 16821859 [PubMed - in process]

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Autoantibodies to the ribosomal P proteins in systemic lupus erythematosus.

Clin Exp Med. 2006 Jun;6(2):49-52

Authors: Reichlin M

This paper describes the clinical significance of antibodies to the ribosomal P proteins in systemic lupus erythematosus. It appears that liver disease due to the lupus process and not attributable to viral infection, alcohol or drugs is associated with anti-ribosomal P. In addition, there is a strong relationship to central nervous system disease and nephritis of antibodies to ribosomal P proteins. The prevalence of the anti-P antibodies is strongly related to disease activity wherein disease remission is associated with disappearance of anti-P antibodies. These phenomena taken together suggest an immunopathogenic role for anti-P antibodies. This idea is strongly supported by the observation that immunoglobulin G containing antiribosomal P activity binds and penetrates living cells with profoundly inhibitory effects on protein synthesis. Finally, a new era of research has been uncovered by the observation that in 54 of 55 instances normal sera passed over a ribosome-sepharose column unmasks anti-P antibodies, which can be eluted from the ribosome column with 3.0 M magnesium chloride. This suggests that anti-idiotypes regulate the expression of anti-P antibodies in normal persons and in lupus patients this regulation is ineffective, with the development of free anti-P antibodies in a proportion of patients with active disease.

PMID: 16820990 [PubMed - in process]

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Citrate Inhibition-Resistant Form of 6-Phosphofructo-1-Kinase from Aspergillus niger.

Appl Environ Microbiol. 2006 Jul;72(7):4515-21

Authors: Mlakar T, Legisa M

Two forms of Aspergillus niger 6-phosphofructo-1-kinase (PFK1) have been described recently, the 85-kDa native enzyme and 49-kDa shorter fragment that is formed from the former by posttranslational modification. So far, kinetic characteristics have never been determined on the enzyme purified to near homogeneity. For the first time, kinetic parameters were determined for individual enzymes with respect to citrate inhibition. The native 85-kDa enzyme was found to be moderately inhibited by citrate, with the K(i) value determined to be 1.5 mM, in the system with 5 mM Mg(2+) ions, while increasing magnesium concentrations relieved the negative effect of citrate. An identical inhibition coefficient was determined also in the presence of ammonium ions, although ammonium acted as a strong activator of enzyme activity. On the other hand, the shorter fragment of PFK1 proved to be completely resistant to inhibition by citrate. Allosteric citrate binding sites were most probably lost after the truncation of the C-terminal part of the native protein, in which region some binding sites for inhibitor are known to be located. At near physiological conditions, characterized by low fructose-6-phosphate concentrations, a much higher efficiency of the shorter fragment was observed during an in vitro experiment. Since the enzyme became more susceptible to the positive control by specific ligands, while the negative control was lost after posttranslational modification, the shorter PFK1 fragment seems to be the enzyme most responsible for generating undisturbed metabolic flow through glycolysis in A. niger cells.

PMID: 16820438 [PubMed - in process]

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Potassium magnesium supplementation for four weeks improves small distal artery compliance and reduces blood pressure in patients with essential hypertension.

Clin Exp Hypertens. 2006 Jul;28(5):489-97

Authors: Wu G, Tian H, Han K, Xi Y, Yao Y, Ma A

It has been postulated that the loss of arterial compliance may precede cardiovascular diseases, and that arterial compliance is an important parameter to consider when evaluating arterial diseases such as essential hypertension (EH) and the effects of antihypertensive treatment. In all, 133 EH patients and 147 healthy subjects were enrolled in this study. Large arterial compliance (C1) and small arterial compliance (C2) were measured by the CVProfilortrade mark DO-2020 CardioVascular Profiling System. Thirty-five patients randomly received magnesium potassium supplementation (magnesium, 70.8 mg/d; potassium, 217.2 mg/d) for four weeks, and 32 patients received lacidipin (4mg/d) as a control. Before and after the four weeks, blood pressure, C1, and C2 were measured. It was found that arterial compliance was significantly lower in EH patients compared with healthy subjects (C1: 12.53 +/- 0.33 vs. 15.63 +/- 0.30 ml/mmHg x 10, p < 0.01;C2: 3.79 +/- 0.17 vs. 5.69 +/- 0.25 ml/mmHg x 100,p < 0.01). On lacidipine, systolic and diastolic BP decreased 13.27 +/- 1.76 mm Hg and 6.33 +/- 1.55 mm Hg, and C1 and C2 compliance values increased 25.05% +/- 4.49% and 34.50% +/- 7.40%, respectively. On K+ and Mg2+ supplementation, systolic and diastolic BP decreased 7.83 +/- 1.87 mm Hg and 3.67 +/- 1.03 mm Hg, and C1 and C2 compliance values increased 12.44% +/- 4.43% and 45.25% +/- 6.67%, respectively. Decreases in systemic vascular resistance (mean arterial pressure divided by cardiac output) by 11.9% and 16.6 % (p < 0.01) were seen between the drug-induced changes, respectively. Both large arterial compliance and small arterial compliance were decreased in essential hypertension patients. In essential hypertension patients, magnesium and potassium supplementation could improve small arterial compliance, while lacidipine improved large arterial compliance significantly.

PMID: 16820345 [PubMed - in process]

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Probing the Active Site of Pseudomonas aeruginosa Porphobilinogen Synthase Using Newly Developed Inhibitors.

Biochemistry. 2006 Jul 11;45(27):8243-8253

Authors: Frère F, Nentwich M, Gacond S, Heinz DW, Neier R, Frankenberg-Dinkel N

Porphobilinogen synthase catalyzes the first committed step of the tetrapyrrole biosynthesis pathway. In an aldol-like condensation, two molecules of 5-aminolevulinic acid (ALA) form the first pyrrole, porphobilinogen. Newly synthesized analogues of a reaction intermediate of porphobilinogen synthase have been employed in studying the active site and the catalytic mechanism of this early enzyme of tetrapyrrole biosynthesis. This study combines structural and kinetic evaluation of the inhibition potency of these inhibitors. In addition, one of the determined protein structures provides for the first time structural evidence of a magnesium ion in the active site. From these results, we can corroborate an earlier postulated enzymatic mechanism that starts with formation of a C-C bond, linking C3 of the A-side ALA to C4 of the P-side ALA through an aldole addition. The obtained data are discussed with respect to the current literature.

PMID: 16819823 [PubMed - as supplied by publisher]

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Crystal structure of trehalose-6-phosphate phosphatase-related protein: biochemical and biological implications.

Protein Sci. 2006 Jul;15(7):1735-44

Authors: Rao KN, Kumaran D, Seetharaman J, Bonanno JB, Burley SK, Swaminathan S

We report here the crystal structure of a trehalose-6-phosphate phosphatase-related protein (T6PP) from Thermoplasma acidophilum, TA1209, determined by the dual-wavelength anomalous diffraction (DAD) method. T6PP is a member of the haloacid dehalogenase (HAD) superfamily with significant sequence homology with trehalose-6-phosphate phosphatase, phosphoserine phosphatase, P-type ATPases and other members of the family. T6PP possesses a core domain of known alpha/beta-hydrolase fold, characteristic of the HAD family, and a cap domain, with a tertiary fold consisting of a four-stranded beta-sheet with two alpha-helices on one side of the sheet. An active-site magnesium ion and a glycerol molecule bound at the interface between the two domains provide insight into the mode of substrate binding by T6PP. A trehalose-6-phosphate molecule modeled into a cage formed by the two domains makes favorable interactions with the protein molecule. We have confirmed that T6PP is a trehalose phosphatase from amino acid sequence, three-dimensional structure, and biochemical assays.

PMID: 16815921 [PubMed - in process]

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Structural studies of human alkaline phosphatase in complex with strontium: implication for its secondary effect in bones.

Protein Sci. 2006 Jul;15(7):1691-700

Authors: Llinas P, Masella M, Stigbrand T, Ménez A, Stura EA, Le Du MH

Strontium is used in the treatment of osteoporosis as a ranelate compound, and in the treatment of painful scattered bone metastases as isotope. At very high doses and in certain conditions, it can lead to osteomalacia characterized by impairment of bone mineralization. The osteomalacia symptoms resemble those of hypophosphatasia, a rare inherited disorder associated with mutations in the gene encoding for tissue-nonspecific alkaline phosphatase (TNAP). Human alkaline phosphatases have four metal binding sites–two for zinc, one for magnesium, and one for calcium ion–that can be substituted by strontium. Here we present the crystal structure of strontium-substituted human placental alkaline phosphatase (PLAP), a related isozyme of TNAP, in which such replacement can have important physiological implications. The structure shows that strontium substitutes the calcium ion with concomitant modification of the metal coordination. The use of the flexible and polarizable force-field TCPEp (topological and classical polarization effects for proteins) predicts that calcium or strontium has similar interaction energies at the calcium-binding site of PLAP. Since calcium helps stabilize a large area that includes loops 210-228 and 250-297, its substitution by strontium could affect the stability of this region. Energy calculations suggest that only at high doses of strontium, comparable to those found for calcium, can strontium substitute for calcium. Since osteomalacia is observed after ingestion of high doses of strontium, alkaline phosphatase is likely to be one of the targets of strontium, and thus this enzyme might be involved in this disease.

PMID: 16815919 [PubMed - in process]

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Bidirectional multisite seizure propagation in the intact isolated hippocampus: The multifocality of the seizure “focus”

Neurobiol Dis. 2006 Jun 28;

Authors: Derchansky M, Rokni D, Rick JT, Wennberg R, Bardakjian BL, Zhang L, Yarom Y, Carlen PL

Localizing the seizure focus is difficult and frequently, multiple sites are found. This reflects our poor understanding of the fundamental mechanisms of seizure generation and propagation. We used multisite electrophysiological recordings in two seizure models and voltage-sensitive dye imaging, to spatiotemporally characterize the initiation and propagation of seizures in an intact epileptogenic brain region, the isolated hippocampus. In low-magnesium perfusate, seizures always originated in the temporal region, and propagated along the septotemporal axis to the septal region. After the seizure spread across the hippocampus, the bursts within a seizure became bidirectional, with different propagation patterns at different frequencies. When the intact hippocampus was separated along the septotemporal axis, independent bidirectional activity was observed in the two halves, and region-specific cuts to the tissue reveal that the CA3 region is critical for seizure generation and propagation. In a second seizure model, using focal tetanic stimulation of the septal and temporal CA3 region, seizures always originated at the stimulated site with bidirectionality later developing at different frequencies, as noted in the low magnesium model, behavior compatible with coupled neuronal network oscillators. These data provide novel insights into the dynamic multifocality of seizure onset and propagation, revealing that the current concept of a single seizure “focus” is complex.

PMID: 16815026 [PubMed - as supplied by publisher]

Intravenous magnesium sulphate decreases postoperative tramadol requirement after radical prostatectomy.

Eur J Anaesthesiol. 2006 Jul 11;:1-5

Authors: Tauzin-Fin P, Sesay M, Delort-Laval S, Krol-Houdek MC, Maurette P

SummaryBackground: The purpose of this study was to assess whether the addition of intravenous magnesium sulphate (Mg) at the induction of anaesthesia to a balanced anaesthetic protocol including wound infiltration, paracetamol and tramadol resulted in improved analgesic efficiency after radical prostatectomy. Methods: We conducted a randomized, double-blind, controlled study. Thirty ASA I or II males scheduled to undergo radical retropubic prostatectomy with general anaesthesia were prospectively assigned to one of the two groups (n = 15 each). The Mg group (Gr Mg) received 50 mg kg-1 of MgSO4 in 100 mL of isotonic saline over 20 min immediately after induction of anaesthesia and before skin incision. The patients in the control group (Gr C) received the same volume of saline over the same period. At the time of abdominal closure, wound infiltration with 190 mg (40 mL) of ropivacaine was performed in both groups. Pain was assessed by a 10-point visual analogue scale in the recovery room starting from the time of tracheal extubation. Standardized postoperative analgesia included paracetamol and tramadol administered via a patient-controlled analgesia device. Results: In the postoperative period, both groups experienced an identical pain course evolution. Cumulative mean tramadol dose after 24 h was 226 mg in the magnesium group and 446 mg in the control group (P < 0.001). Postoperative nausea occurred in two patients in each group. Two vs. eight patients required analgesic rescue in magnesium and control groups, respectively (P = 0.053). Conclusions: This study shows that intravenous magnesium sulphate reduces tramadol consumption when used as a postoperative analgesic protocol in radical prostatectomy.

PMID: 16834789 [PubMed - as supplied by publisher]

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Hydrogeochemistry of seasonal variation of Urmia Salt Lake.

Saline Systems. 2006 Jul 11;2(1):9

Authors: Alipour SS

ABSTRACT: Urmia Lake has been designated as an international park by the United Nations. The lake occupies a 5700 km2 depression in northwestern Iran. Thirteen permanent rivers flow into the lake. Water level in the lake has been decreased 3.5 m in the last decade due to a shortage of precipitation and progressively dry climate. Geologically the lake basin is considered to be a graben of tectonic origin. Na, K, Ca, Li and Mg are the main cations with Cl, SO4, and HCO3 as the main anions. F & Br are the other main elements in the lake. A causeway crossing the lake is under construction, which may affect the lakes annual geochemistry. The main object of this project is mainly to consider the potential of K-mineral production along with ongoing salt production. Seven hundred and four samples were taken and partially analyzed for the main cations and anions. Surface water (0.5 m. depth) was analyzed for Na, K, Mg, Ca, Br and Li, and averaged 87.118 g/lit, 1.48 g/lit, 4.82 g/lit, 4.54 g/lit, 1.19 ppm and 12.7 ppm respectively for the western half of the lake. Sodium ranged between 84 to 91.2 g/lit, and showed higher concentrations in the south than in the north. This unexpected result may be caused by shallower depth in the south and a higher net evaporation effect. Calcium ranged between 4.2 to 5 g/lit, apparently slightly higher in the north. K is higher in the south, possibly due to rivers entering from south that may carry slightly higher K in solution. In the middle-range samples (0.5- 5m.), K averaged 1.43 g/lit and ranged from 1.40 to 1.46 g/lit. At this intermediate depth the distribution of K is clearly higher to the south of the causeway that is currently under construction. It is not clear whether this increase is the effect of the causeway or the effect of the salty Aji-Chay River to the east, and the Khoy salt domes to the north of the lake. At depth (5m.-10m), K averaged 1.48 g/lit and ranged from 1.4 to 1.49 g/lit, differing only in the second decimal from the average of the middle and surface samples. Ignoring the small difference between the averages of the three sample depths, the distribution of K is highly homogeneous in the lake water due to the mixing process. Therefore causeway construction has not yet strongly affected K distribution, or it may be at the starting point. Magnesium concentration ranged from 4.6 to 5-g/lit, and was elevated in the south. This differs somewhat compared to calcium. Lithium, with an average of 12-13 ppm, is slightly higher in the south, and has not shown any significant variation in all three seasons. Iodine was below the detection limit in the lake. Urmia Lake, geochemically, is highly uniform both to the south and north of the causeway, in both the surface and deep brines. K and Mg, which average 1.48 and 6.6 g/lit in order, could be elements worth production in addition to the NaCl currently being produced from the lake. Br, F, Li and B in the limit of <50 ppm dont look to be in the economical range.

PMID: 16834770 [PubMed - as supplied by publisher]

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Are elevated admission calcium levels associated with better outcomes after ischemic stroke?

Neurology. 2006 Jul 11;67(1):170-3

Authors: Ovbiagele B, Liebeskind DS, Starkman S, Sanossian N, Kim D, Razinia T, Saver JL

Calcium (Ca(2+)) and magnesium (Mg(2+)) influence the molecular pathways of ischemic neuronal death. The authors evaluated the impact of admission serum Ca(2+) and Mg(2+) levels, on incident stroke severity and discharge functional outcome. After adjusting for covariates, higher admission Ca(2+) was significantly associated with lesser stroke severity and better discharge functional outcome. Admission Mg(2+) was not an independent clinical outcome prognosticator.

PMID: 16832104 [PubMed - in process]

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Prehistoric agricultural depletion of soil nutrients in Hawai’i.

Proc Natl Acad Sci U S A. 2006 Jul 18;103(29):11092-7

Authors: Hartshorn AS, Chadwick OA, Vitousek PM, Kirch PV

We investigated the fate of soil nutrients after centuries of indigenous dryland agriculture in Hawai’i using a coupled geochemical and archaeological approach. Beginning approximately 500 years ago, farmers began growing dryland taro and sweet potato on the leeward slopes of East Maui. Their digging sticks pierced a subsurface layer of cinders, enhancing crop access to the soil water stored below the intact cinders. Cultivation also catalyzed nutrient losses, directly by facilitating leaching of mobile nutrients after disturbing a stratigraphic barrier to vertical water movement, and indirectly by increasing mineral weathering and subsequent uptake and harvest. As a result, centuries of cultivation lowered volumetric total calcium, magnesium, sodium, potassium, and phosphorus content by 49%, 28%, 75%, 37%, and 32%, respectively. In the absence of written records, we used the difference in soil phosphorus to estimate that prehistoric yields were sufficient to meet local demand over very long time frames, but the associated acceleration of nutrient losses could have compromised subsequent yields.

PMID: 16832047 [PubMed - in process]

Dietary intake in immigrant Arabian pregnant women.

Saudi Med J. 2006 Jul;27(7):1019-21

Authors: Alevizos AG, Stamatiou KN, Lacroix RE, Natzar MA, Mihas CC, Bovis KD, Panagopoulos PP, Mariolis AD

OBJECTIVE: We examined the intake of dietary micronutrients of immigrant Arabian pregnant women in Greece, in order to investigate the possible factors influencing food intake and affecting the overall nutritional profile. METHODS: A dietary assessment of 497 immigrant Arabian pregnant women, admitted to the Obstetrics and Gynecology Department, Outpatient Clinic, Tzaneion General Hospital, Piraeus city, Vyronas Health Center, and Alexandras General Hospital, Athens, Greece was performed between August 2002 and August 2005, along with a comparison of micronutrient intake with the latest dietary recommendations. We carried out blood analysis, and measurements of serum micronutrients in all participants. RESULTS: Four hundred and sixty-seven out of 497 (94%) women followed the traditional Arabian diet, and did not use drug medication or supplements during gestation. The mean dietary intakes of vitamin E, vitamin B12, vitamin C, zinc, calcium and phosphorus in the 2nd and 3rd trimesters were similar to the respective values of the Dietary Reference Intake, while the mean dietary intake of vitamin D was relatively low. The mean intakes of folic acid and iron were lower than the respective values, while the mean intakes of vitamin A and magnesium was slightly higher. The results of the laboratory tests were normal in 470 women (94.5%) except those regarding iron deficiency anemia, which was relatively common. CONCLUSION: Our findings suggest that apart from iron and folic acid supplementation, no further changes would be necessary in the dietary patterns of immigrant Arabian pregnant women, since their traditional nutritional habits seem to provide all micronutrients in sufficient quantities.

PMID: 16830023 [PubMed - in process]

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Vascular endothelial growth factor increases the intracellular magnesium.

Biochem Biophys Res Commun. 2006 Aug 25;347(2):496-501

Authors: Hong BZ, Kang HS, So JN, Kim HN, Park SA, Kim SJ, Kim KR, Kwak YG

Vascular endothelial growth factor (VEGF) is one of the key players in the process of angiogenesis. However, its underlying mechanism remains unclear. Mg(2+) is the most abundant intracellular divalent cation in the body and plays critical roles in many cell functions. We investigated the effect of VEGF on intracellular Mg(2+) in human umbilical vein endothelial cells (HUVECs). VEGF-A(165) increased the intracellular Mg(2+) concentration ([Mg(2+)](i)) in a dose-dependent manner, with or without extracellular Mg(2+), and the increase of [Mg(2+)](i) was blocked by pretreatment with SU1498, tyrosine kinase inhibitors (tyrphostin A-23 and genistein), phosphatidylinositol 3-kinase (PI3K) inhibitors (wortmannin and LY294002) or phospholipase Cgamma (PLCgamma) inhibitor (U73122). In contrast, mitogen-activated protein kinase inhibitors (SB202190 and PD98059) had no effect on the VEGF-induced [Mg(2+)](i) increase. These results suggest that VEGF-A(165) increases the [Mg(2+)](i) from the intracellular Mg(2+) stores through the tyrosine kinase/PI3K/PLCgamma-dependent signaling pathways.

PMID: 16828056 [PubMed - in process]

Intraerythrocyte and serum electrolytes in diabetic patients with hypertension.

J Coll Physicians Surg Pak. 2006 Jul;16(7):445-9

Authors: Yasmin F, Haleem DJ, Haleem MA

Objective: To determine the serum and intraerythrocyte concentrations of vasoactive ions in patients of diabetes mellitus of either gender with hypertension. Design: Cross-sectional study. Place and Duration of Study: The Department of Biochemistry, University of Karachi, from May-June 2002. Patients and Methods: The study was conducted on 48 volunteers. Out of 48, 24(12 men and 12 women) were hypertensive patients with diabetes mellitus. Remaining (12 men and 12 women) were normal healthy subjects. Biochemical estimations were done by flame photometry and spectrophotometry. Data were analyzed by Two-way ANOVA followed by Newman-Keuls test. Results: A decrease in serum concentrations of sodium, calcium, magnesium, phosphorus, chloride and intraerythrocyte potassium and an increase in the levels of glucose, haematocrit and intraerythrocyte sodium was observed in both male and female patients with diabetes mellitus and hypertension. No significant changes were observed in serum potassium levels. Conclusion: The results suggest that dysregulations of electrolyte balance caused by hyperinsulinemia or altered glucose metabolism may lead to hypertension.

PMID: 16827953 [PubMed - in process]

Effect of polyols and salts on the Acid-induced state of human placental cystatin.

Biochemistry (Mosc). 2006 Jun;71(6):619-26

Authors: Rashid F, Sharma S, Baig MA, Bano B

Polyols (glycerol and sorbitol) and salts (magnesium sulfate, sodium sulfate, and magnesium chloride) have been used to study the refolding of the acid-induced state of human placental cystatin (HPC), which is a low molecular weight (12,500 daltons) thiol proteinase inhibitor, in terms of CD spectroscopy, binding of hydrophobic dye 1-anilinonaphthalene-8-sulfonic acid (ANS), and intrinsic fluorescence measurements. The helical content of acid-denatured HPC increased with increase in glycerol concentration (0-80%). At 80% glycerol concentration, the secondary structural features observed in the far UV-CD region are similar to those of the native state (pH 6.0). The intrinsic fluorescence and near UV-CD studies showed that this 80% glycerol-induced state has a significant amount of tertiary structure with decreased ANS binding compared to the acid-denatured state. It was found that glycerol is more effective in stabilizing the acid-denatured state of HPC as compared to sorbitol. Among salts the stability effect was more for MgCl2 (used up to concentration of 3 M) compared to MgSO4 and Na2SO4 (used up to the concentration of 1.5 M due to restricted solubility of HPC at higher sulfate salt concentrations) as determined by CD studies and fluorescence measurements, which showed secondary and tertiary structural resemblance of this MgCl2-induced state close to native state and showed overall spectral features in between the native state and the acid-denatured state. This MgCl2 (3 M)-induced state showed decreased ANS fluorescence as compared to the acid-denatured state but more than that of the native state. The results taken together suggest that the acid-denatured state of HPC in the presence of 80% glycerol or 3 M MgCl2 has a conformation in between that of the native state (pH 6.0) and the acid-induced state at pH 2.0.

PMID: 16827653 [PubMed - in process]

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Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients.

Br J Sports Med. 2006 Jul 6;

Authors: Pokan R, Hofmann P, von Duvillard SP, Smekal G, Wonisch M, Lettner K, Schmid P, Shechter M, Silver B, Bachl N

Previous studies have demonstrated that in patients with coronary artery disease (CAD) an upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection is correlated with a diminished stress-dependent left ventricular function. Magnesium (Mg) supplementation improves endothelial function, exercise tolerance, and exercise-induced chest pain in patients with CAD. Purpose: We studied the effects of oral Mg therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD. METHODS: In a double-blind controlled trial, 53 male patients with stable CAD, were randomized to either oral Mg 15 mmol twice daily (N = 28, age = 61 inverted exclamation mark&Oacute9 yrs, height = 171 inverted exclamation mark&Oacute7, body weight = 79 inverted exclamation mark&Oacute10 kg, previous myocardial infarction (MI), N = 7) or placebo (N = 25, age = 58 inverted exclamation mark&Oacute10 yrs, height = 172 inverted exclamation mark&Oacute6, body weight = 79 inverted exclamation mark&Oacute10 kg, previous MI, N = 6) for 6 months. Maximal oxygen uptake (VO2max), the degree and direction of the deflection of the HR performance curve described as factor k f not 0 (upward deflection) and the left ventricular ejection fraction (LVEF), were the outcomes measured. RESULTS: Six-month Mg therapy significantly increased intracellular Mg levels (32.7 inverted exclamation mark&Oacute2.5 vs. 35.6 inverted exclamation mark&Oacute2.1 mEq/L, p<0.001) compared to placebo (33.1 inverted exclamation mark&Oacute3.1.9 vs. 33.8 inverted exclamation mark&Oacute 2.0 mEq/L, n.s.), VO2max (28.3 inverted exclamation mark&Oacute6.2 vs. 30.6 inverted exclamation mark&Oacute7.1 ml/kg/min, p<0.001; 29.3 inverted exclamation mark&Oacute5.4 vs. 29.6 inverted exclamation mark&Oacute5.2 ml/kg/min, n.s.), factor k (-0.298 inverted exclamation mark&Oacute0.242 vs. -0.208 inverted exclamation mark&Oacute0.260, p<0.05; -0.269 inverted exclamation mark&Oacute0.336 vs. -0.272 inverted exclamation mark&Oacute0.335, n.s.), LVEF (58 inverted exclamation mark&Oacute11 vs. 67 inverted exclamation mark&Oacute10 %, p<0.001; 55 inverted exclamation mark&Oacute11 vs. 54 inverted exclamation mark&Oacute12 %, n.s.). CONCLUSION: The present study supports the intake of oral Mg and its favorable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.

PMID: 16825271 [PubMed - as supplied by publisher]

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A Fourier transform infrared spectroscopic study of Mg-rich, Mg-poor and acid leached palygorskites.

Spectrochim Acta A Mol Biomol Spectrosc. 2006 Jul 3;

Authors: Cai Y, Xue J, Polya DA

The FTIR spectra of pure magnesium-rich (Mg-rich) and magnesium-poor (Mg-poor) palygorskites, before and after short-term (<7h) and long-term (360h) acid leaching are presented here. Comparison of decomposition spectra of Mg-rich and Mg-poor palygorskites clearly shows that the absorption peaks related to pairs of octahedral cation differ depending on the octahedral site occupancy. Short-term acid leaching of palygorskites results in significant changes to FTIR absorption bands near 1200 and 790cm(-1). As the acid attack progresses, the band at 1200cm(-1) shifts to lower wavenumbers, whilst the band at 790cm(-1), which here is assigned to Si(U)-O-Si(D) symmetrical stretching vibration, shifts to higher wavelengths. Longer-term leaching of palygorskites results in the disappearance of 900-1200cm(-1) absorption bands, showing that the palygorskite has largely decomposed to amorphous silica. Assignments of several other bands have been made as follows: several vibrations relate to OH, i.e. 847cm(-1), hygroscopic water (1635cm(-1)), Si-O vibrations 1100, 611-621, 470-481cm(-1), etc. appear in the FTIR spectra of 360h acid leached palygorskite. Three bands near 1100, 611-621 and 470-481cm(-1) relate to Si-O vibration of an ideal hexagonal (Si(2)O(5))(n) sheet.

PMID: 16824788 [PubMed - as supplied by publisher]

A very high incidence of low 25 hydroxy-vitamin D serum concentration in a French population of patients with primary hyperparathyroidism.

J Endocrinol Invest. 2006 Jun;29(6):511-5

Authors: Boudou P, Ibrahim F, Cormier C, Sarfati E, Souberbielle JC

Since the demonstration that vitamin D status might influence the clinical and biological expression of primary hyperparathyroidism (PHPT), a serum 25-hydroxy vitamin D (25-OHD) concentration of 50 nmol/l has been considered by an expert panel as the minimum level to be maintained in asymptomatic PHPT patients. Two yr after this recommendation, we aimed to evaluate the frequency of serum 25-OHD concentrations below this threshold in PHPT patients. In the present study, serum 25-OHD, second- and third-generation PTH, calcium, phosphate, magnesium, albumin and creatinine were measured in 72 out 145 consecutive PHPT patients operated on in our Endocrine Surgery Department, in whom blood samples were available before as well as two days after surgical intervention. Before surgery, the frequency of serum 25-OHD levels <50 nmol/l ranged from 91.5 to 100% whatever the classification used to identify patients: whole group, symptomatic vs asymptomatic, patients with calcium levels >3 vs <3 mmol/l. 25-OHD concentrations correlated negatively with the weight of adenoma, PTH levels, and total calcium concentrations measured before surgery. Pre-operative PTH levels, whatever the assay used, and total calcium concentrations were positively and significantly correlated. Two days post-surgery, 13 patients were moderately hypocalcemic. Neither pre-surgery 25-OHD nor PTH, calcium or phosphorus level or adenoma weight were predictive of post-operative hypocalcemia. The dramatic frequency of low 25-OHD concentrations in our PHPT patients demonstrates that the above-mentioned recommendation is far from being applied in France despite evidence of worsening expression of PHPT with decreasing 25-OHD serum levels.

PMID: 16840828 [PubMed - in process]

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Removal of terephthalic acid in alkalized wastewater by ferric chloride.

J Hazard Mater. 2006 Jun 3;

Authors: Wen YZ, Tong SP, Zheng KF, Wang LL, Lv JZ, Lin J

Terephthalic acid, which is a main component in alkali-decrement wastewater, is efficiently removed using ferric chloride in high pH solutions. About 90% removal of terephthalic acid is achieved at pH between 8 and 11. Especially, the removal reached 94.3% at pH 11. However, as the pH increased from pH 12 and 13, the low removal of terephthalic acid were found. The increasing ferric chloride dosage had a dramatic positive impact on the achieved removal of terephthalic acid. Further increase in the ferric chloride dosage did not produce better removal rate. The increase of terephthalic acid concentration also led to the increase of ferric chloride dosage in order to get the same removal of terephthalic acid. There was approximately a negative linear relationship between terephthalic acid concentration and removal of terephthalic acid. Compared with other coagulants, it can be seen that ferric chloride is more effective in a high pH solution and the amount of ferric chloride required is also less as compared with aluminum chloride, magnesium chloride and calcium chloride. Our results clearly showed that terephthalate anions strongly binds to positive Fe(OH)(3) flocs and forms insoluble complexes, probably through a mechanism involving electrostatic attraction. The electrostatic attraction may be particularly useful means of purifying wastewater in high pH solutions.

PMID: 16839672 [PubMed - as supplied by publisher]

Magnesium sulfate neither potentiates nor inhibits tissue plasminogen activator-induced thrombolysis.

J Thromb Haemost. 2006 Jul;4(7):1575-9

Authors: Stewart D, Marder VJ, Starkman S, Saver JL

BACKGROUND: Increasing circulating magnesium concentrations to 2-fold over normal baseline may afford a neuroprotective effect in patients with acute cerebral ischemia. OBJECTIVES: As patients receiving magnesium sulfate (MgSO(4)) in human clinical trials may also be candidates for subsequent thrombolytic therapy with tissue plasminogen activator (t-PA), preclinical assessment of possible inhibition or potentiation of fibrinolytic activity by MgSO(4) has important clinical relevance. METHODS: We utilized an in vitro system, in which D-dimer release served as a reflection of t-PA-induced clot lysis, to measure the effect of magnesium at the target concentration being tested in human stroke clinical trials, and at 2- and 3-fold higher levels. Clots from normal volunteers were exposed to t-PA at concentrations that correspond to therapeutic or endogenous plasma t-PA levels. RESULTS: MgSO(4) had no effect on t-PA-induced clot lysis at up to 3-fold target magnesium concentration (6x normal serum concentration). CONCLUSIONS: MgSO(4) concentrations well above the targeted level in therapeutic stroke trials does not affect t-PA-induced fibrinolytic activity, and therefore is a suitable agent for trials of combined neuroprotective and thrombolytic therapy in patients with acute ischemic stroke.

PMID: 16839356 [PubMed - in process]

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Magnesium bistrifluoromethanesulfonimide as a new and efficient acylation catalyst.

J Org Chem. 2006 Jul 21;71(15):5785-8

Authors: Chakraborti AK, Shivani S

Magnesium bistrifluoromethanesulfonimide catalyzed the acetylation of phenols, alcohols, and thiols under solvent-free conditions at room temperature and in short times. Electron-deficient and sterically hindered phenols provided excellent yields. The catalyst was found to be general for acylation with other anhydrides, such as propionic, isobutyric, pivalic, chloroacetic, and benzoic anhydrides. The rate of acylation was influenced by the electronic and steric factors associated with the anhydride. The reaction with less electrophilic anhydrides (e.g., chloroacetic and benzoic anhydrides) required higher temperature ( approximately 80 degrees C). Chemoselective acetylation, pivalation, and benzoylation took place with acid-sensitive alcohols without any competitive dehydration/rearrangement.

PMID: 16839166 [PubMed - in process]

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Lithium carbenoids-ultra-reactive yet selective reagents for methylenation and halomethylenation of sulfones(1).

J Org Chem. 2006 Jul 21;71(15):5646-57

Authors: Pearlman BA, Putt SR, Fleming JA

The first efficient, one-pot method for methylenation of p-toluyl sulfones (i.e., the transformation of p-MePhSO(2)CHR(2) into R(2)CCH(2)) is described. Methods for effecting that transformation involving alkylation of sulfones with reagents of the general formula MCH(2)X, where M = SiMe(3), SnR(3), and MgCl (the Julia method) have been previously described. However, the silicon reagent is completely unreactive toward many sulfones, the tin reagent typically affords only moderate yields, and the magnesium reagent typically gives incomplete reaction (9-40% starting material). This article reports that excellent yields are obtained by alkylating the sulfone with the more ionic lithium methylene carbenoids (LiCH(2)X, where X = Cl, Br, and I). For example, treatment of sulfone 1 with 3 equiv of n-BuLi (THF, -100 degrees C) followed by 2 equiv of CH(2)Br(2) affords olefin 2 in 96% yield. Although the carbenoid is generated in the presence of a 1:2 mixture of alpha-lithio-sulfone and n-BuLi, it reacts selectively with the alpha-lithio-sulfone (K(rel) = 9.6 +/- 0.8 with LiCH(2)Br). The chlorocarbenoid LiCH(2)Cl reacts somewhat less selectively (K(rel) = 3.5). The alkyl-substituted carbenoid n-BuCHBrLi reacts >/= 40 times more slowly than LiCH(2)Br, suggesting that olefination occurs by the S(N)2 mechanism rather than by metal-assisted ionization (MAI), the mechanism by which cyclopropyl and vinylidene carbenoids react with nucleophiles. Finally, sulfones can be transformed into vinyl halides by treatment with 3 equiv of n-BuLi (THF, -78 degrees C), followed by >2 equiv of diisopropylamine, followed by 3 equiv of dihalomethane (CH(2)X(2), where X(2) = Cl(2), BrCl, Br(2), or I(2)). All products are formed in high yield and purity.

PMID: 16839145 [PubMed - in process]

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A multielement masking method using magnesium hydroxide coprecipitation for the selective determination of lead in water samples by differential pulse anodic stripping voltammetry.

Anal Sci. 2006 Jul;22(7):1021-4

Authors: Yabutani T, Utsunomiya Y, Kado Y, Tani Y, Kishimoto H, Fukuda A, Motonaka J

We present a new multielement masking method using magnesium hydroxide coprecipitation for the selective determination of Pb by differential pulse anodic stripping voltammetry (DPASV). The recovery of Pb in the masking method was over 95%, while interfering ions (Cd(2+), Co(2+), Cu(2+), Fe(3+), Mn(2+), and Ni(2+)) could be removed at 100% from the analytical sample. A linear regression was obtained in the Pb concentration from 10 to 1000 microg kg(-1) in the existence of 100 microg kg(-1) of the interfering ions. When this method was applied to the determination of Pb in a natural water-standard reference material (NIST 1640), the determined value for Pb in this work (25.4 +/- 4.1 microg kg(-1)) almost agreed with the certified value (27.89 +/- 0.14 microg kg(-1)).

PMID: 16837757 [PubMed - in process]

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Studies on high-energy collision-induced dissociation of endogenous cannabinoids: 2-arachidonoylglycerol and n-arachidonoylethanolamide in FAB-mass spectrometry.

Anal Sci. 2006 Jul;22(7):921-30

Authors: Kasai HF, Tsubuki M, Honda T

Analysis of 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamide (anandamide) via alkali or alkaline earth metal-adduct high-energy collision-induced dissociation (CID) in fast-atom bombardment (FAB) ionization-mass spectrometry (MS) is described. The CID-MS/MS of the [2-AG+Li](+) or [2-AG+Na](+) ion undergoes charge-remote fragmentation (CRF), which is useful for the determination of the double-bond positions in the hydrocarbon chain, while the CID-MS/MS of the [2-AG-H+Cat](+) (Cat = Mg(2+), Ca(2+), Ba(2+)) ion provides an abundant fragment ion of the cationized arachidonic acid species, which is derived from cleaving the ester bond via a McLafferty-type rearrangement in addition to structurally informative CRF ions in small amounts. On the other hand, the CID-MS/MS spectra of anandamide cationized with both alkali metal (Li(+) or Na(+)) and alkaline earth metal (Mg(2+), Ca(2+), or Ba(2+)) show CRF patterns: the spectra obtained in lithium or sodium adduct are more clearly visible than those in magnesium, calcium, or barium adduct. The McLafferty rearrangement is not observed with metal-adduct anandamide. The characteristics in each mass spectrum are useful for the detection of these endogenous ligands. m-Nitrobenzyl alcohol (m-NBA) is the most suitable matrix. A lithium-adduct [2-AG+Li](+) or [anandamide+Li](+) ion is observed to be the most abundant in each mass spectrum, since the affinity of lithium for m-NBA is lower than that for other matrices examined.

PMID: 16837740 [PubMed - in process]

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The effect of temperature on the QTc interval in the newborn infant receiving extracorporeal membrane oxygenation (ECMO).

Early Hum Dev. 2006 Jul 10;

Authors: Horan M, Edwards AD, Firmin RK, Ablett T, Rawson H, Field D

OBJECTIVE: To explore the changes in the QTc interval during mild hypothermia in neonates receiving extracorporeal membrane oxygenation (ECMO). DESIGN: Twenty seven neonates (median gestation 40 weeks; range 33-41 weeks) enrolled in a pilot study of mild hypothermia were studied during the first five days of ECMO. The first group (N=7) were maintained at 37 degrees C throughout the study period. Subsequent groups (N=5) were cooled to 36 degrees C, 35 degrees C and 34 degrees C respectively for twenty four hours and the final group to 34 degrees C for forty eight hours before being rewarmed to 37 degrees C. Using a 24 h digital monitor, the QT and QTc intervals were recorded continuously during the cooling and rewarming period and validated using standard 12 lead electrocardiograms. Patients were carefully assessed clinically and routine biochemistry (including magnesium and calcium) laboratory tests measured pre ECMO and at timed intervals during cooling and rewarming. RESULTS: The mean difference between the continuous digital and 12 lead ECG values for QTc was -13.3 ms. During the first 24 h of cooling, the mean (95th centile) values for the digitally measured QTc interval at 37 degrees C=431(506) milliseconds (ms); 36 degrees C=459(521) ms; 35 degrees C=445(516) ms; 34 degrees C=465(531) ms; 34 degrees C for 48 h=466(521) ms. During this period overall QTc increased by 3.12 ms (95% confidence intervals 6.17 to 0.84; p=0.04) for each degree fall in body temperature. During rewarming, there was no significant relationship between QTc and temperature change. No serious arrhythmias were during cooling. Using univariate analysis, no relationship was found between QTc and electrolytes, heart rate and blood pressure. CONCLUSIONS: QTc shows significant variability in individuals, and only a small proportion of this can be explained by rectal temperature. Mild hypothermia was not associated with serious cardiac arrhythmias.

PMID: 16837147 [PubMed - as supplied by publisher]

Intra-articular magnesium is effective for postoperative analgesia in arthroscopic knee surgery.

Br J Anaesth. 2006 Jul 11;

Authors: Bondok RS, Abd El-Hady AM

BACKGROUND: Several medications are commonly injected intra-articularly for postoperative analgesia after arthroscopic knee surgery. Among the potentially efficient substances, magnesium could be of particular interest through its NMDA-receptor blocking properties. METHODS: A total of 60 patients undergoing arthroscopic knee surgery were randomly and double-blindly assigned to two groups to receive intra-articular injection of either 10 ml of magnesium sulphate (MgSO4) (50 mg ml(-1)) (Group M) or 10 ml of normal saline (Group C). Analgesic effect was evaluated by measuring pain intensity (visual analogue scale; VAS) 1, 2, 6, 8, 12, 18 and 24 h after operation and the time delay between MgSO4 or saline administration and the first requirement of supplementary analgesic medication by the patient (diclofenac). RESULTS: Intra-articular magnesium administration resulted in a significant reduction in pain scores in Group M compared with Group C 1, 2, 6 and 8 h after the end of surgery [1.7 (0.59), 2.2 (0.69), 2.8 (1.01) and 3.5 (1.10) in Group M; 8.0 (1.25), 5.9 (1.12), 4.4 (0.67) and 4.5 (1.13) in Group C, respectively]. A longer delay between intra-articular injection of the study medication and first administration of diclofenac was observed in Group M [667 (198) min] as compared with Group C [49 (13) min]. Total diclofenac consumption was significantly lower in Group M [37.5 (38.14) mg] than in Group C [117.5 (46.95) mg]. No early side-effects were noted. CONCLUSION: Intra-articular magnesium is effective for postoperative analgesia in arthroscopic knee surgery.

PMID: 16835255 [PubMed - as supplied by publisher]

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Management of Chemotherapy-induced Peripheral Neuropathy.

Curr Pain Headache Rep. 2006 Jul;10(4):279-87

Authors: Stillman M, Cata JP

Recent advances in the development and administration of chemotherapy for malignant diseases have been rewarded with prolonged survival rates. The cost of progress has come at a price and the nervous system is frequently the target of chemotherapy-induced neurotoxicity. Unlike more immediate toxicities that effect the gastrointestinal tract and bone marrow, chemotherapy-induced neurotoxicity is frequently delayed in onset and may progress over time. In the peripheral nervous system, the major brunt of the toxicity is directed against the peripheral nerve, resulting in chemotherapy-induced peripheral neuropathy (CIPN). Chemotherapeutic agents used to treat hematologic and solid tumors target a variety of structures and functions in the peripheral nervous system, including the neuronal cell body, the axonal transport system, the myelin sheath, and glial support structures. Each agent exhibits a spectrum of toxic effects unique to its mechanism of toxic injury, and recent study in this field has yielded clearer ideas on how to mitigate injury. Combined with the call for a greater recognition of the potentially devastating ramifications of CIPN on quality of life, basic and clinical researchers have begun to investigate therapy to prevent neurotoxic injury. Preliminary studies have shown promise for some agents including glutamine, glutathione, vitamin E, acetyl-L-carnitine, calcium, and magnesium infusions, but final recommendations await prospective confirmatory studies.

PMID: 16834943 [PubMed - in process]

Gitelman syndrome: report of three cases and literature review.

Kaohsiung J Med Sci. 2006 Jul;22(7):357-62

Authors: Lee YT, Wang IF, Lin TH, Huang CT

Gitelman syndrome (GS) is a rare autosomal recessive, inherited renal tubular disorder. Herein, we report three cases of GS, one sporadic case and two siblings. They have typical laboratory findings, including hypokalemia, metabolic alkalosis, hypomagnesemia, and hypocalciuria. All of them were treated with oral potassium and magnesium supplements. They received regular pediatric clinic follow-up to check electrolytes and monitor development. These three cases reminded us that doctors should be alert to unexplained hypokalemia, which is usually the initial presentation of GS.

PMID: 16849105 [PubMed - in process]

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Self-Assembly of Natural Light-Harvesting Bacteriochlorophylls of Green Sulfur Photosynthetic Bacteria in Silicate Capsules as Stable Models of Chlorosomes.

Bioconjug Chem. 2006 Jul 19;17(4):988-994

Authors: Saga Y, Akai S, Miyatake T, Tamiaki H

Naturally occurring bacteriochlorophyll(BChl)s-c, -d, and -e from green sulfur photosynthetic bacteria were self-assembled in an aqueous solution in the presence of octadecyltriethoxysilane and tetraethoxysilane, followed by polycondensation of the alkoxysilanes by incubation for 50 h at 25 degrees C. The resulting BChl self-assemblies in silicate capsules exhibited visible absorption and circular dichroism spectra similar to the corresponding natural light-harvesting systems (chlorosomes) of green sulfur bacteria. Dynamic light scattering measurements indicated that the silicate capsules had an average hydrodynamic diameter of several hundred nanometers. BChl self-aggregates in silicate capsules were significantly stable to a nonionic surfactant Triton X-100, which was apt to decompose the BChl aggregates to their monomeric form, compared with conventional micelle systems. BChls in silicate capsules were more tolerant to demetalation of the central magnesium under acidic conditions than the natural systems.

PMID: 16848406 [PubMed - as supplied by publisher]

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Effects of antenatal magnesium sulfate and corticosteroid therapy on sleep states of preterm infants.

Res Nurs Health. 2006 Jul 17;29(4):269-280

Authors: Black B, Holditch-Davis D, Schwartz T, Scher MS

This exploratory longitudinal study was designed to compare the neonatal illness severity, sleep-wake, and respiratory sleep behaviors of preterm infants whose mothers received prenatal corticosteroids and/or magnesium sulfate (MgSO(4)) with those of infants whose mothers did not receive these medications. The 134 infants were divided into four groups: those whose mothers received MgSO(4) only, those who received steroids only, those who received both MgSO(4) and steroids, and those who received neither. The groups did not differ on infant characteristics or illness severity. Infants exposed to MgSO(4) had more active sleep without rapid eye movement, indicating poorly organized active sleep. The MgSO(4)-only group had higher quiet sleep regularity scores and fewer state changes. These findings suggest that fetal exposure to MgSO(4) may subtly affect the central nervous system. (c) 2006 Wiley Periodicals, Inc. Res Nurs Health 29: 269-280, 2006.

PMID: 16847907 [PubMed - as supplied by publisher]