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Magnesium Concentration (magnesium + concentration)
Selected AbstractsGrowth and Hematological Changes of Rockfish, Sebastes schlegeli (Hilgendorf) Exposed to Dietary Cu and CdJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2005Ju-Chan Kang Cd and Cu toxicological effect on growth and hematological parameters was investigated in juvenile rockfish Sebasres schlegeli after sub-chronic dietary Cd (0, 0.5, 5, 25, and 125 mg/kg) and Cu exposure (0, 50, 125, 250, and 500 mg/kg) for 60 d. In the experiment of dietary Cd exposure, weight and length SGR of the rockfish were significantly different from control, and a significant inverse relationship was observed between weight gain and the exposure concentration of dietary Cd at 25, 125 mg/kg (P > 0.05). Hematwrit and hemoglobin decreased significantly and were dose dependently in all Cd exposure. Glucose in serum was also increased significantly (P < 0.05). The concentration of total protein in serum was significantly lower than control at 5, 25, and 125 mgkg. No differences were observed in serum calcium concentration. Magnesium concentration in serum was increased signillcantly with dietary Cd concentration. In the experiment of dietary Cu exposure, Cu was inhibited weight gain and growth rate. No differences were observed in hematocrit, hemoglobin and RBCs compared to control. Contents of total protein, glucose, and Ca in serum remained stable. Mg concentration in serum was increased significantly at 500 mg/kg. [source] Cardiac basal metabolism: energetic cost of calcium withdrawal in the adult rat heartACTA PHYSIOLOGICA, Issue 3 2010P. Bonazzola Abstract Aim:, Cardiac basal metabolism upon extracellular calcium removal and its relationship with intracellular sodium and calcium homeostasis was evaluated. Methods:, A mechano-calorimetric technique was used that allowed the simultaneous and continuous measurement of both heat rate and resting pressure in arterially perfused quiescent adult rat hearts. Using pharmacological tools, the possible underlying mechanisms related to sodium and calcium movements were investigated. Results:, Resting heat rate (expressed in mW g,1dry wt) increased upon calcium withdrawal (+4.4 ± 0.2). This response was: (1) unaffected by the presence of tetrodotoxin (+4.3 ± 0.6), (2) fully blocked by both, the decrease in extracellular sodium concentration and the increase in extracellular magnesium concentration, (3) partially blocked by the presence of either nifedipine (+2.8 ± 0.4), KB-R7943 (KBR; +2.5 ± 0.2), clonazepam (CLO; +3.1 ± 0.3) or EGTA (+1.9 ± 0.3). The steady heat rate under Ca2+ -free conditions was partially reduced by the addition of Ru360 (,1.1 ± 0.2) but not CLO in the presence of EGTA, KBR or Ru360. Conclusion:, Energy expenditure for resting state maintenance upon calcium withdrawal depends on the intracellular rise in both sodium and calcium. Our data are consistent with a mitochondrial Ca2+ cycling, not detectable under normal calcium diastolic levels. The experimental condition here analysed, partially simulates findings reported under certain pathological situations including heart failure in which mildly increased levels of both diastolic sodium and calcium have also been found. Therefore, under such pathological conditions, hearts should distract chemical energy to fuel processes associated with sodium and calcium handling, making more expensive the maintenance of their functions. [source] Intracellular Calcium Increase in Epileptiform Activity: Modulation by Levetiracetam and LamotrigineEPILEPSIA, Issue 7 2004Antonio Pisani Summary:,Purpose: Alterations in neuronal calcium (Ca2+) homeostasis are believed to play an essential role in the generation and propagation of epileptiform events. Levetiracetam (LEV) and lamotrigine (LTG), novel antiepileptic drugs (AEDs), were tested on epileptiform events and the corresponding elevations in intracellular Ca2+ concentration ([Ca2+]i) recorded from rat neocortical slices. Methods: Electrophysiological recordings were performed from single pyramidal neurons from a slice preparation. Spontaneous epileptiform events consisting of long-lasting, repetitive paroxysmal depolarization shifts (PDSs) and interictal spike activity were induced by reducing the magnesium concentration from the solution and by adding bicuculline and 4-aminopyridine. Simultaneously, microfluorimetric measurements of [Ca2+]i were performed. Optical imaging with Ca2+ indicators revealed a close correlation between Ca2+ transients and epileptiform events. Results: Both LEV and LTG were able to reduce both amplitude and duration of PDSs, as well as the concomitant elevation in [Ca2+]i, in a dose-dependent fashion. Whole-cell patch-clamp recordings from isolated neocortical neurons revealed that LEV significantly reduced N-, and partially P/Q-type high-voltage-activated (HVA) Ca2+ currents, whereas sodium currents were unaffected. Interestingly, the inhibitory effects of LEV were mimicked and occluded by LTG or by a combination of ,-conotoxin GVIA and ,-agatoxin IVA, selective blockers of N- and P/Q-type HVA channels, respectively, suggesting a common site of action for these AEDs. Conclusions: These results demonstrate that large, transient elevations in neuronal [Ca2+]i correlate to epileptiform discharges. The antagonistic effects of LEV and LTG on [Ca2+]i overload might represent the basis for their anticonvulsant efficacy and could preserve neuronal viability. [source] Effect of Water Hardness on the Taste of Alkaline Electrolyzed WaterJOURNAL OF FOOD SCIENCE, Issue 4 2005Masamichi Koseki ABSTRACT: The effect of water hardness on the taste of alkaline electrolyzed water (AEW) was examined by sensory evaluation. Sensory test 1 of commercial bottled mineral water to which calcium and/or magnesium salts had been added was performed by panelists who evaluated the effect of hardness on the taste of water using a scoring method (hedonic scaling test) and a 1-pair comparison method. The water, in which the calcium concentration and the magnesium concentration was 20 mg/L and 2 mg/L, respectively, was found to taste better than any water containing other concentrations of calcium and magnesium. Sensory test 2 of bottled mineral waters having hardnesses of 30 mg/L to 290 mg/L, of activated carbon filtration water having a hardness of 50 mg/L, and of AEWs was performed by panelists using a scoring method (hedonic scaling test) and a pair test, and their preferences for the taste of AEWs was surveyed. The taste of AEW made by electrolyzing activated carbon filtration water did not differ from that of the water before it was electrolyzed. The same was true of AEW made by electrolyzing bottled mineral water having a hardness of 80 mg/L. However, 3 kinds of AEWs made by electrolyzing bottled mineral waters having hardnesses of 30 mg/L, 170 mg/L, and 290 mg/L were found to taste less pleasant than each bottled mineral water before being electrolyzed. The results of sensory tests 1 and 2 show that good-tasting AEW could be produced by an alkaline water electrolyzed from most tap water of Japan because its hardness varies from approximately 50 mg/L to 80 mg/L. [source] Prevalence and Incidence of Serum Magnesium Abnormalities in Hospitalized CatsJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2002Jeffrey Toll Total serum magnesium concentration ([Mg2+]s) was prospectively determined for 57 cats admitted to the intensive care unit (ICU) of the Cornell University Hospital for Animals. Data were collected and analyzed to determine the following: prevalence and incidence of [Mg2+]s abnormalities, medical disorders associated with altered [Mg2+]s, association of altered [Mg2+]s with other electrolyte abnormalities, length of hospitalization for cats with abnormalities of [Mg2+]s versus those with normal [Mg2+]s, and survival of cats with abnormal [Mg2+]s versus those with normal [Mg2+]s. The point prevalence of magnesium abnormalities was 26%, the period prevalence was 46%, and the cumulative incidence was 23%. Hypermagnesemia was associated with abnormalities of serum potassium (P= .04) and phosphate (P= .01) concentrations. Abnormalities of [Mg2+]s were not associated with abnormal serum concentrations of Na+, Ca2+, or Cl - . On admission, hypomagnesemia was detected in cats with gastrointestinal, endocrine, and other disorders; hypermagnesemia was detected only in cats with renal disease, obstructive uropathy, or neoplastic disease. The median hospital stay for cats that developed abnormal [Mg2+]s after admission was longer than for cats that remained nor-momagnesemic (5 versus 4 days, respectively; P= .03). Despite the longer hospital stay, the survival of these cats was lower than that of normomagnesemic cats (54 versus 77%; P= .05). When all cats were considered, the survival of cats with abnormal [Mg2+]s also was decreased compared with normomagnesemic cats (62 versus 81%; P= .05). We conclude that abnormalities of [Mg2+]s may affect morbidity and mortality of affected cats. [source] Magnesium and sulphur in the calcite shells of two brachiopods, Terebratulina retusa and Novocrania anomalaLETHAIA, Issue 1 2007JENNIFER ENGLAND This study determines the distribution of magnesium and sulphur in the shells of two species of brachiopod from the same environment to highlight environmental and biological influences on shell composition. In Terebratulina retusa there are differences in magnesium concentration between the primary layer and the outer and inner regions of the secondary layer. In contrast, Novocrania anomala has a shell composed of high magnesium calcite and there is no significant difference in magnesium concentration between the primary and the secondary shell layers. Sulphur provides an indication of the distribution of sulphated organic matrix within the shells of T. retusa and N. anomala. In T. retusa the distribution of magnesium and sulphur correlates across the shell; however, there is no evidence for a relationship between magnesium and sulphur distribution in N. anomala. The relationship between magnesium and sulphur in T. retusa indicates that a proportion of the magnesium content of the shell is associated with the sulphated fraction of the organic matrix. In these two species of brachiopod, from the same environment, magnesium and organic concentration and distribution are very different, emphasizing the importance of fully understanding the factors that control biomineral composition before the application of these biominerals to environmental studies. [source] MAGNESIUM-RICH INTRALENSAR STRUCTURES IN SCHIZOCHROAL TRILOBITE EYESPALAEONTOLOGY, Issue 5 2007MARTIN R. LEE Abstract:, The interpretation of the lenses of schizochroal trilobite eyes as aplanatic doublets by Clarkson and Levi-Setti over 30 years ago has been widely accepted. However, the means of achieving a difference in refractive index across the interface between the two parts of each lens to overcome spherical aberration has remained a matter of speculation and lately it has been argued that the doublet structure itself is no more than a diagenetic artefact. Recent advances in technologies for imaging, chemical analysis and crystallographic characterization of minerals at high spatial resolutions have enabled a re-examination of the structure of calcite lenses at an unprecedented level of detail. The lenses in the eyes of the specimen of Dalmanites sp. used in the original formulation of the aplanatic doublet hypothesis are shown to have undergone diagenetic alteration, but its products reflect original differences in mineral chemistry between the upper lens unit and lower intralensar bowl. The turbidity of the bowl and of the core within the upper part of the lens are the result of their greater microporosity and abundance of microdolomite inclusions, both of which were products of diagenetic replacement of original magnesian calcite in these areas. Such a difference in magnesium concentration in the original calcite has long been postulated as one of the ways by which the interface between these lens units could have produced an aberration-free image and the present study provides the first direct evidence of such a chemical contrast, thus confirming the doublet hypothesis. [source] The effect of environmental factors on the distribution of Neoparamoeba pemaquidensis in TasmaniaJOURNAL OF FISH DISEASES, Issue 10 2005M Douglas-Helders Abstract Aquaculture in Tasmania is mostly carried out in estuaries. These estuarine habitats show a great variety and form unique environments in which Neoparamoeba pemaquidensis, the amoebic gill disease (AGD)-causing protozoan, may or may not survive. Tasmania is divided into two zones, one where AGD is present and one where AGD is absent, but any ecological data to rationalize this distribution is lacking. In in vitro trials N. pemaquidensis strains were exposed to different concentrations of ammonium sulphate, copper sulphate, copper sulphate and tannin, and different Neoparamoeba densities, salinities and temperatures. A trial using field water samples investigated the survival of N. pemaquidensis in waters sourced from AGD-free and AGD-positive zones, and water analysis was performed to determine any differences. Significantly decreased protozoan survival was found with exposure to increasing copper sulphate concentrations from 10 to 100 000,m (P < 0.001), salinity of 15, (P < 0.001), low Neoparamoeba densities of 625 and 1250 cells mL,1 (P = 0.0005), and water sourced from Macquarie Harbour (P < 0.001). The water chemistry of this AGD-free zone showed significantly lower dissolved calcium and magnesium concentrations which may contribute to this area being AGD-free. Understanding of the ecology of N. pemaquidensis will enable better control and prevention strategies for Tasmanian salmon growers. [source] Studies on cerebrospinal fluid ionized calcium and magnesium concentrations in convulsive childrenPEDIATRICS INTERNATIONAL, Issue 4 2004Yusaku Miyamoto AbstractBackground:,The concentrations of ionized calcium (iCa) and ionized magnesium (iMg) were measured in the cerebrospinal fluid (CSF) of convulsive and non-convulsive children, to investigate the relationship between seizure manifestation and CSF iCa and iMg concentrations. Standard concentrations of CSF iCa and iMg were also established. Methods:,CSF samples from 23 patients, ages 0,15 years, with various forms of seizures and 26 age-matched non-convulsive children were collected by lumbar puncture. CSF was obtained anaerobically and the concentrations of CSF iCa and iMg were measured with an electolyte analyzer (Stat Profile Ultra M1, NOVA, USA) immediately after the lumbar puncture. Results:,The concentrations of CSF iCa were significantly higher in non-convulsive children younger than 11 months old compared with children older than 12 months. The concentrations of CSF iMg in non-convulsive children did not differ significantly with aging. The concentrations of CSF iCa in convulsive children did not differ significantly from the concentrations of non-convulsive children. The concentrations of CSF iMg in convulsive children were significantly lower than in non-convulsive children. Conclusion:,These results suggest that seizure manifestation is related to age-dependent changes in iCa and decreased iMg in the developing brain. [source] An Evaluation of the Impact of Oral Magnesium Lactate on the Corrected QT Interval of Patients Receiving Sotalol or Dofetilide to Prevent Atrial or Ventricular Tachyarrhythmia RecurrenceANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2006Brian F. McBride Pharm.D. Background: Intravenous magnesium reduces the QTc interval of patients receiving ibutilide. Whether oral magnesium can reduce the QTc interval associated with oral sotalol and dofetilide is not known. This study was undertaken to evaluate the impact of oral magnesium on the QTc interval and whether an inherent intracellular magnesium deficiency exists among patients with arrhythmias. Methods: Participants receiving sotalol or dofetilide for atrial or ventricular arrhythmias were randomized to receive magnesium l -lactate (504 mg elemental magnesium daily, Niche Pharmaceuticals, Roanoke, TX) or placebo for 48 hours. A 12-lead electrocardiogram (ECG) was obtained at baseline, 3 hours, and 51 hours after dosing to correspond to the Tmax after oral ingestion. The QTc interval was measured from the ECGs and compared between groups. Intracellular magnesium concentrations were determined by energy-dispersive x-ray analysis at baseline and 51 hours after dosing (Intracellular Diagnostics, Inc., Foster City, CA). Results: The QTc interval reductions from baseline were greater in the magnesium group than placebo at 3 and 51 hours (P = 0.015 and P < 0.001, respectively). Sixty-three percent of patients (regardless of experimental group) had baseline intracellular magnesium concentrations below the normal reference range of 33.9,41.9 mEq/IU, with an average level of 32.6 ± 2.2 mEq/IU. Conclusions: Oral magnesium l -lactate raises intracellular magnesium concentrations and lowers the QTc interval of patients receiving sotalol or dofetilide. [source] A Comparison of the Soil Water, Nutrient Status, and Litterfall Characteristics of Tropical Heath and Mixed-Dipterocarp Forest Sites in Brunei,BIOTROPICA, Issue 1 2000Jonathan A. Moran ABSTRACT Two of the main hypotheses to explain the distribution and special characteristics of tropical heath forest are nutrient and water limitation. A study was undertaken to investigate both factors on two sites under tropical heath forest (Badas Forest Reserve) and mixed-dipterocarp forest (Andulau Forest Reserve) in Brunei. Soil water potentials were monitored at depths of 20, 50, and 90 cm over wet and dry periods for five months at each site. The results showed the mixed-dipterocarp forest site to be drier at 50 cm depth compared to the tropical heath forest site. There was no significant difference in water potentials between sites at 20 or 90 cm. Nutrient concentrations in the soil solution were monitored at the same depths over a seven-month period at the same sites. A 12-month litterfall study was also undertaken to monitor nutrient returns from the canopy at each site. The results of both studies suggest that the tropical heath forest site is poorer in nitrogen, but richer in calcium, than the mixed-dipterocarp forest site. The results for phosphorus are less clear, but do not suggest that its limitation is a significant factor at the tropical heath forest site compared to the mixed-dipterocarp forest site. Phosphorus and magnesium concentrations in the soil solution showed a strong positive correlation with sliding 30-day rainfall totals at both sites. [source] | ||||||||||||||||