Calcium In Medium Research Articles

Rapid fabrication of vascularized and innervated cell-laden bone models with biomimetic intrafibrillar collagen mineralization

Bone tissue, by definition, is an organic–inorganic nanocomposite, where metabolically active cells are embedded within a matrix that is heavily calcified on the nanoscale. Currently, there are no strategies that replicate these definitive characteristics of bone tissue. Here we describe a biomimetic approach where a supersaturated calcium and phosphate medium is used in combination with a non-collagenous protein analog to direct the deposition of nanoscale apatite, both in the intra- and extrafibrillar spaces of collagen embedded with osteoprogenitor, vascular, and neural cells. This process enables engineering of bone models replicating the key hallmarks of the bone cellular and extracellular microenvironment, including its protein-guided biomineralization, nanostructure, vasculature, innervation, inherent osteoinductive properties (without exogenous supplements), and cell-homing effects on bone-targeting diseases, such as prostate cancer. Ultimately, this approach enables fabrication of bone-like tissue models with high levels of biomimicry that may have broad implications for disease modeling, drug discovery, and regenerative engineering.

Investigation of the medium calcium based non-burnt brick made by red mud and fly ash: durability and hydration characteristics

Red mud is a type of highly alkaline waste residue produced in the process of alumina smelting by the Bayer process. Based on the idea of medium calcium content, solid wastes such as red mud and fly ash were used to prepare non-burnt bricks; and the mass ratio of CaO/SiO2 was selected in the range of 0.88–1.42. Mechanical properties and durability were investigated with a compressive strength test. X-ray diffractometry (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques were used to characterize the hydration characteristic. The environmental performance was analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP). The results indicated that the mechanical properties and the durability were optimal when the mass ratio of CaO/SiO2 was 1.23. The hydration products were mostly C-S-H gel, ettringite, Na4Ca(Si10Al16)O32·12H2O and Ca3Al2(SiO4)(OH)8. They were responsible for the strength development, and the CaO/SiO2 mass ratio of 1.23 had the best polymerized structure. The results of an environmental performance test showed that the heavy metals in the raw materials were well-solidified in the brick. Therefore, this paper provides an effective solution for use of solid wastes in building material.

Efficient microalgae harvesting mediated by polysaccharides interaction with residual calcium and phosphate in the growth medium

This study sets out to harvest microalgae through auto-flocculation by manipulating the interactive effect of calcium, phosphate, and polysaccharides (PSAs). The harvesting efficiency (H.E) of 91 ± 2.7% was achieved for Ettlia sp. through auto-flocculation. The H.E was attributed to the chelation of calcium and PSAs present in microalgae medium. In the absence of PSAs, the H.E reduced to 64 ± 05% only. The addition of phosphate (34 ± 0.13 mg L−1) increased the H.E to 73 ± 1.5%. Zeta-potential measurements showed that the harvesting was induced by charge neutralization and inter-particle bridging. The PSAs-based auto-flocculation was tested for Chlorella sp. too but it turned out the H.E of 51 ± 1.3% only. The flocculation did not take place when the co-harvesting of Ettlia sp. and Chlorella sp. was carried out. It is concluded that each microalgae specie shows different auto-flocculation mechanism due to variation in their PSAs characteristics. It triggers up the need for setting up a distinct protocol for different microalgae species to assess their auto-flocculation potential.

Participation of the inositol 1,4,5-trisphosphate-gated calcium channel in the zona pellucida- and progesterone-induced acrosome reaction and calcium influx in human spermatozoa.

The acrosome reaction is a prerequisite for fertilization, and its signaling pathway has been investigated for decades. Regardless of the type of inducers present, the acrosome reaction is ultimately mediated by the elevation of cytosolic calcium. Inositol 1,4,5-trisphosphate-gated calcium channels are important components of the acrosome reaction signaling pathway and have been confirmed by several researchers. In this study, we used a novel permeabilization tool BioPORTER® and first demonstrated its effectiveness in spermatozoa. The inositol 1,4,5-trisphosphate type-1 receptor antibody was introduced into spermatozoa by BioPORTER® and significantly reduced the calcium influx and acrosome reaction induced by progesterone, solubilized zona pellucida, and the calcium ionophore A23187. This finding indicates that the inositol 1,4,5-trisphosphate type-1 receptor antibody is a valid inositol 1,4,5-trisphosphate receptor inhibitor and provides evidence of inositol 1,4,5-trisphosphate-gated calcium channel involvement in the acrosome reaction in human spermatozoa. Moreover, we demonstrated that the transfer of 1,4,5-trisphosphate into spermatozoa induced acrosome reactions, which provides more reliable evidence for this process. In addition, by treating the spermatozoa with inositol 1,4,5-trisphosphate/BioPORTER® in the presence or absence of calcium in the culture medium, we showed that the opening of inositol 1,4,5-trisphosphate-gated calcium channels led to extracellular calcium influx. This particular extracellular calcium influx may be the major process of the final step of the acrosome reaction signaling pathway.

Respiration and microbial biomass quantification in Southern Colombia Andisols

Soil respiration was evaluated by quantifying CO2 and carbon from microbial biomass (CBM) in a livestock production system that integrates different land uses, located south-east of the municipality of Pasto. The evaluated uses correspond to secondary forest, prairie and silvopastoral system (Ssp), at two depths (0-10 cm and 10-20 cm). A completely randomised design was used in a 3x2 factorial arrangement (Factor A: uses, Factor B: depths). The soils presented a sandy loam texture, moderately acidic pH, high cation exchange capacity, high organic carbon content, medium calcium, magnesium and potassium content, and low phosphorus content. The classification analysis allowed the formation of three groups that coincided with the three land uses evaluated, where the Ssp presented the highest number of variables above the general average of the study. The Anova showed a p-value <0.001 for the interaction use * depth; Tukey’s means comparison tests allowed establishing that the highest respiration values occurred in the forest at a depth of 0-10 cm (1.89 mg-1 CO2 C g-1 soil-1), while in the Ssp at a 10-20 cm depth the lowest respiration values occurred (0.072 mg-1 CO2 C g-1 soil-1). The CBM presented higher values in the forest at a depth of 0-10 cm (179.19 μg-1C g-1 soil-1) and lower values in the Ssp at a depth of 0-10cm (117.72 μg-1C g-1 soil-1).

Oleanolic Acid and Ursolic Acid Improve Bone Properties and Calcium Balance and Modulate Vitamin D Metabolism in Aged Female Rats.

Oleanolic acid (OA) and ursolic acid (UA) are the major chemical constituents in Fructus Ligustri Lucidi (FLL), a kidney-tonifying Chinese herb that is previously shown to improve bone properties and enhance calcium balance in aged female rats. The present study was designed to study if OA and UA act as the active ingredients in FLL to exert the positive effects on bone and mineral metabolism in aged rats. Aged (13-month-old) Sprague-Dawley female rats were randomly assigned to four groups with oral administration of drug or vehicle treatment for 12 weeks: medium calcium diet (MCD, 0.6% calcium), high calcium diet (HCD, 1.2% calcium), MCD + FLL (700 mg/kg/day), MCD + OA (23.6 mg/kg/day) + UA (8.6 mg/kg/day). A group of mature (3-month-old) female rats fed with MCD was included as positive control. The results demonstrated that FLL and OA+UA increased bone mineral density and improved microarchitectural properties of aged female rats. The osteoprotective effects of FLL and OA+UA might be, at least in part, associated with their actions on enhancing calcium balance and suppressing age-induced secondary hyperparathyroidism in aged female rats. FLL and OA+UA also significantly induced renal CYP27B1 protein expression and OA+UA treatment decreased CYP24A1 mRNA and protein expressions in aged female rats. In addition, FLL and OA+UA significantly increased the promoter activity, mRNA and protein expressions of renal CYP27B1 in vitro in human proximal tubule HKC-8 cells. The present findings suggest that OA+UA can be regarded as the active ingredients of FLL and might be a potential drug candidate for prevention and treatment of osteoporosis.

Effects of low phosphorus intake on serum calcium, phosphorus, alkaline phosphatase activity and parathyroid hormone in growing dogs.

A sufficient and balanced supply of calcium and phosphorus is important mainly for the skeletal health of dogs, especially during growth. Numerous reports and research results are quoted, which focus mainly on the effects of both deficient or excessive calcium supplies. The important role that phosphorus plays in the disruption to skeletal development is also explored. The aims of this study were to evaluate the effects of a low phosphorus supply on selected serum parameters of calcium and phosphorus metabolism in both medium and large breed growing dogs, alongside the effects on the apparent digestibility and retention of these minerals as well as the musculoskeletal development, which were published before. Beagle and Foxhound-crossbred puppies (n=53) between the age of 6 and 24weeks were either fed a balanced (control) or a low phosphorus diet, the latter one providing about one-third of P amount fed to the control group. In regular intervals, blood samples were obtained to measure serum levels of phosphorus, calcium, alkaline phosphatase activity (ALP) and parathyroid hormone (PTH). Functional Additive Mixed Models were used to analyse these serum concentrations per group and per diet. In the puppies being fed the low phosphorus diet, a distinct decline of serum phosphate concentration was detected with a more pronounced and prolonged effect in the smaller Beagles. At the same time, serum calcium concentration altered in the opposite direction, implying that the product of calcium multiplied by phosphorus was regulated more closely than the calcium to phosphorus ratio. The PTH concentrations were reduced and ALP activity increased at certain time points during the low phosphorus feeding compared to the puppies being fed the control diet. In the latter group, an effect of time or maturation could be demonstrated in relation to the serum phosphate concentration.

In vitro response of mesenchymal stem cells to biomimetic hydroxyapatite substrates: A new strategy to assess the effect of ion exchange

Biomaterials can interact with cells directly, that is, by direct contact of the cells with the material surface, or indirectly, through soluble species that can be released to or uptaken from the surrounding fluids. However, it is difficult to characterise the relevance of this fluid-mediated interaction separately from the topography and composition of the substrate, because they are coupled variables. These fluid-mediated interactions are amplified in the case of highly reactive calcium phosphates (CaPs) such as biomimetic calcium deficient hydroxyapatite (CDHA), particularly in static in vitro cultures. The present work proposes a strategy to decouple the effect of ion exchange from topographical features by adjusting the volume ratio between the cell culture medium and biomaterial (VCM/VB). Increasing this ratio allowed mitigating the drastic ionic exchanges associated to the compositional changes experienced by the material exposed to the cell culture medium. This strategy was validated using rat mesenchymal stem cells (rMSCs) cultured on CDHA and beta-tricalcium phosphate (β-TCP) discs using different VCM/VB ratios. Whereas in the case of β-TCP the cell response was not affected by this ratio, a significant effect on cell adhesion and proliferation was found for the more reactive CDHA. The ionic exchange, produced by CDHA at low VCM/VB, altered cell adhesion due to the reduced number of focal adhesions, caused cell shrinkage and further rMCSs apoptosis. This was mitigated when using a high VCM/VB, which attenuated the changes of calcium and phosphate concentrations in the cell culture medium, resulting in rMSCs spreading and a viability over time. Moreover, rMSCs showed an earlier expression of osteogenic genes on CDHA compared to sintered β-TCP when extracellular calcium fluctuations were reduced. Statement of SignificanceFluid mediated interactions play a significant role in the bioactivity of calcium phosphates. Ionic exchange is amplified in the case of biomimetic hydroxyapatite, which makes the in vitro characterisation of cell-material interactions especially challenging. The present work proposes a novel and simple strategy to explore the mechanisms of interaction of biomimetic and sintered calcium phosphates with mesenchymal stem cells. The effects of topography and ion exchange are analysed separately by modifying the volume ratio between cell culture medium and biomaterial. High ionic fluctuations interfered in the maturation of focal adhesions, hampering cell adhesion and leading to increased apoptosis and reduced proliferation rate.

Effects of deoxynivalenol exposure on cerebral lipid peroxidation, neurotransmitter and calcium homeostasis of chicks in vivo

During current research, the effects of deoxynivalenol (DON) exposure on cerebral lipid peroxidation, neurotransmitter secretion and calcium homeostasis in chicks were evaluated. One hundred and twenty Hailan chicks (male, 1-day-old) were randomly divided into four groups. Chicks in low, medium and high dose groups were fed with 0.27, 1.68 and 12.21 mg/kg−1 DON respectively by gavage according to feed intake. Chicks in control group were fed with physiological saline by gavage. The trials were conducted for 36 d. At the end of the trials, twenty chicks per group were sacrificed, and the cerebra were collected for measuring the brain indices. Compared with the control group, the activities of total superoxide dismutase (T-SOD) and glutathione peroxidase were significantly decreased in treatment groups (P < 0.05), the contents of malondialdehyde in high dose group were increased (P < 0.05), the catalase activities and nitric oxide contents in medium and high dose groups were decreased (P < 0.05), and the activities of T-AOC in high dose group were reduced (P < 0.05). Compared with the control group, the concentrations of norepinephrine and 5-hydroxytryptamine in high dose group were obviously increased (P < 0.05), while the concentrations of dopamine were decreased (P < 0.05). Meanwhile, the concentrations of calcium and calmodulin (CaM) in medium and high dose groups were lower than those of the control group (P < 0.05), and the gene relative expression of CaM mRNA in treatment groups were significantly reduced (P < 0.05), in a dose-dependent manner. These results suggested that DON exposure can affect the cerebral lipid peroxidation, neurotransmitters secretion and the balance of calcium homeostasis in chicks.

Calcium chloride-enriched calcium aluminate cement promotes invitro osteogenesis.

To evaluate the effects of 2.8% or 10% calcium chloride (CaCl2 ) in calcium aluminate cement (CAC) with either bismuth oxide (Bi2 O3 ) or zinc oxide (ZnO) as radiopacifiers on the progression of osteogenic cell cultures. Rat calvaria-derived cells were grown on Thermanox® coverslips for 24h and exposed to samples of (i) CACb: with 2.8% CaCl2 and 25% Bi2 O3 ; (ii) CACb+: with 10% CaCl2 and 25% Bi2 O3 ; (iii) CACz: with 2.8% CaCl2 and 25% ZnO; or (iv) CACz+: with 10% CaCl2 and 25% ZnO, placed on inserts. Nonexposed cultures served as the control. Calcium and phosphorus contents in culture media were quantified. The effects of the cementson cell apoptosis, cell viability and acquisition of the osteogenic cell phenotype were evaluated. Data werecompared by Kruskal-Wallis test (α=5%). CACb+ promoted the highest levels of calcium in the culture media; CACz+, the lowest levels of phosphorus (P<0.05). CACz+ and CACb increased cell apoptosis (P<0.05). CACb reduced cell viability (P<0.05) and the expression of the osteoblastic phenotype. CACz+ and CACb+ promoted greater cell differentiation and matrix mineralization compared to CACz and CACb (P<0.05). For CAC with the lower CaCl2 content, the use of Bi2 O3 was detrimental for osteoblastic cell survival and differentiation compared to ZnO, while CAC with the higher CaCl2 content supported the acquisition of the osteogenic cell phenotype invitro regardless of the radiopacifier used. Thus, CAC with 10% CaCl2 would potentially promote bone repair in the context of endodontic therapies.

Lower dietary phosphorus supply in pigs match both animal welfare aspects and resource efficiency

Dietary phosphorus frequently exceeds age-specific requirements and pig manure often contains high phosphorus load which causes environmental burden at regional scales. Therefore, feeding strategies towards improved phosphorus efficiency and reduced environmental phosphorus load have to be developed. A 5-week feeding trial was conducted: piglets received medium, lower (−25%), or higher (+25%) amounts of phosphorus and calcium. Dietary responses were reflected by performance parameters, bone characteristics, and molecular data retrieved from serum, intestinal mucosa, and kidney cortex (p < 0.05). Transcripts associated with vitamin D hydroxylation (Cyp24A1, Cyp27A1, Cyp27B1) were regulated by diet at local tissue sites. Low-fed animals showed attempts to maintain mineral homoeostasis via intrinsic mechanisms, whereas the high-fed animals adapted at the expense of growth and development. Results suggest that a diet containing low phosphorus and calcium levels might be useful to improve resource efficiency and to reduce phosphorus losses along the agricultural value chain.

The Kinase ERULUS Controls Pollen Tube Targeting and Growth in Arabidopsis thaliana.

In this paper, we describe the role of the receptor-like kinase ERULUS (ERU) in PT growth of Arabidopsis thaliana. In silico analysis and transcriptional reporter lines revealed that ERU is only expressed in pollen and root hairs (RHs), making it a tip growth-specific kinase. Deviations from Mendelian inheritance were observed in the offspring of self-pollinated heterozygous eru plants. We found that in vivo eru PT targeting was disturbed, providing a possible explanation for the observed decrease in eru fertilization competitiveness. Extracellular calcium perception and intracellular calcium dynamics lie at the basis of in vivo pollen tube (PT) tip growth and guidance. In vitro, ERU loss-of-function lines displayed no obvious PT phenotype, unless grown on low extracellular calcium ([Ca2+]ext) medium. When grown at 12 the normal [Ca2+]ext, eru PTs grew 37% slower relative to WT PTs. Visualization of cytoplasmic [Ca2+]cyt oscillations using the Yellow Cameleon 3.6 (YC3.6) calcium sensor showed that, unlike in WT PTs, eru apical [Ca2+]cyt oscillations occur at a lower frequency when grown at lower [Ca2+]ext, consistent with the observed reduced growth velocity. Our results show that the tip growth-specific kinase ERULUS is involved in regulating Ca2+-dependent PT growth, and most importantly, fertilization efficiency through successful PT targeting to the ovules.

Plakophilin3 increases desmosome assembly, size and stability by increasing expression of desmocollin2

Previous reports show that the desmosomal plaque protein plakophilin3 (PKP3) is essential for desmosome formation. Here, we report that PKP3 over-expression decreases calcium dependency for de novo desmosome formation and makes existing cell-cell adhesion junctions more resilient in low calcium medium due to an increase in desmocollin2 expression. PKP3 overexpression increases the stability of other desmosomal proteins independently of the increase in DSC2 levels and regulates desmosome formation and stability by a multimodal mechanism affecting transcription, protein stability and cell border localization of desmosomal proteins.

Divergent effects of Wnt/\u03b2-catenin signaling modifiers on the preservation of human limbal epithelial progenitors according to culture condition

Wnt signaling plays an important role in the regulation of self-renewal in stem cells. Here we investigated the effect of CHIR99021, the primary transducer of the Wnt signaling canonical pathway, and IWP2, a wide action Wnt signal blocker, on the growth and differentiation of the limbal epithelial progenitor cells when these cells are cultured in two different, common culture approaches, outgrowth from limbal biopsy explants and isolated cell seeded in low calcium medium. Consistent with their expected effects, irrespective of the culture system, IWP2 decreased total β-catenin while CHIR99021 increased it in nuclear localization. However, IWP2 increased stem/progenitor cell marker (p63α and ABCG2) content and clonogenic capacity in the explants but had opposite effects on isolated cells. CHIR99021 reduced the growth rate, stem/progenitor cell marker content and clonogenic capacity in the explants but also had the opposite effect on the isolated cells. These results show that the outcome of Wnt/β-catenin signaling modification is dependent on the culture systems. Transplantation of limbal epithelial sheets from explant cultures is one of the standard treatments of limbal stem cell deficiency. Our study shows that Wnt-associated activity has a strong negative impact on stem/progenitor cell preservation in limbal explant cultures.

Solvent extraction separate of zinc and cadmium from magnesium and calcium in sulfuric acid medium by mixing extractants

Synergistic extraction has been proven to enhance extractability and selectivity for the separation of cadmium and zinc from magnesium and calcium in the sulfuric acid medium with Mextral V10 and Mextral 622H (aromatic hydroxamic) mixtures diluted in DT100. Mixtures of Mextral V10 and 622H are highly selective for Zn and Cd over Mg and Ca compared with the single Mextral V10, resulting in larger synergistic shifts for zinc and cadmium with the ΔpH50 (Zn–Ca) values increasing substantially from 0.83 to 1.73 pH units and ΔpH50 (Cd–Ca) values increasing from 0.63 to 2.13 pH units. The aqueous to organic ratio (A/O ratio), the saponification ratio of Mextral V10 and extracting agent concentration were studied on the effect of metal ions extraction, which helped to increase the organic capacity of metal extraction. The McCabe-Thiele plot for Cd and Zn extraction with 5% (volume fraction) Mextral V10 and 5% Mextral 622H extractants mixture indicate the necessity of only one theoretical stages at an A/O ratio of 1.5:1. One stage extraction simulation test conducted at pH 6.50 shows that Cd and Zn reach the extraction of 99.6% and 97.9%, respectively, and only low levels of magnesium and calcium are extracted in the organic phase. The extracted Zn2+ or Cd2+-organic species are Zn(A1)(A2) or Cd(A1)(A2) with the mixture system by slope analysis.

Induction of hypocalcemia in non-lactating, non-pregnant Holstein cows fed negative DCAD rations with low, medium or high concentrations of calcium

Prepartum feeding of a negative dietary cation-anion difference (-DCAD) ration has proved to be an effective method of preventing hypocalcemia. However, the optimum Ca concentration to feed with -DCAD rations has not been determined. We conducted an experiment to assess the implications of feeding a low, medium, and high concentration Ca -DCAD ration on the ability of a cow to respond to an induction of hypocalcemia.

Effect of Activators on Strength of Hybrid Alkaline Cement

Hybrid alkaline cement is a class of alkaline cement resulted from alkali activation of the medium calcium content of aluminosilicate materials. This paper presents an experimental analysis of alkali activators effect on strength of hybrid alkaline cement produced from 80% fly ash and 20% ordinary Portland cement. Two alkali activators were observed i.e. 5% sodium sulfate and a combination of 5% of sodium sulfate-1.1 M SiO2 of sodium silicate solution. Compressive strength tests were performed on 20mmx 40mm cylinder paste specimens while setting time tests were conducted by Vicat needle. Scanning electron microscopy analysis and measurement of fly ash reaction degree were performed to explain the compressive strength of paste. It is concluded that addition of soluble silicate on the dry mix of hybrid cement-sodium sulfate activator reduce compressive strength and shorten the setting time. Both of activators give relative low fly ash reaction degree.

Increasing Calcium Level Limits Schwann Cell Numbers In Vitro following Peripheral Nerve Injury

Background After peripheral nerve injury, there is an increase in calcium concentration in the injured nerves. Our previous publications have shown that increase in calcium concentration correlated well with degree of nerve injury and that local infusion of calcitonin has a beneficial effect on nerve recovery. Schwann cells play a pivotal role in regeneration and recovery. We aim to examine cultured Schwann cell survivals in various concentrations of calcium-containing growth media and the effect of calcitonin in such media. Methods To establish baseline in postinjury state, crush injury was induced in male Sprague-Dawley rats' sciatic nerves. Extra- and intraneural calcium concentrations were measured. To study Schwann cell survival, uninjured sciatic nerve segment was harvested and cultured in media containing various amounts of calcium. To study the effect of calcitonin, nerve harvest and culture were done in four additional media: (1) normal control, (2) normal control with calcitonin, (3) high calcium medium, and (4) high calcium medium with calcitonin. Schwann cells were studied and analyzed under fluorescent conditions. Results With increasing calcium concentration, there was a significant decrease in the number of Schwann cells. For the experimental groups, in which calcitonin had been added to the growth medium, there were similar amounts of Schwann cells present in both high and low calcium-containing medium. Conclusion Schwann cells are sensitive to increasing calcium concentration. Calcitonin counteracts the detrimental effects of high calcium on Schwann cell survival. This can have significant future clinical implications for patients with peripheral nerve injuries.

Effects of benzo(a)pyrene exposure on the ATPase activity and calcium concentration in the hippocampus of neonatal rats.

To investigate whether postnatal benzo(a)pyrene (B(a)P) exposure caused the impairments on the process of neurodevelopment and the alteration in the calcium medium in the neonatal rats. Eighty neonatal Sprague Dawley (SD) rats were randomly divided into 5 groups (untreated control group, vehicle group, 0.02 mg/kg, 0.2 mg/kg and 2 mg/kg B(a)P-exposed group). Rats were treated with B(a)P by the intragastric administration from postnatal day (PND) 4 to 25. Morris water maze (MWM) was employed to observe the spatial memory of rats. The activity of calcium adenosine triphosphatase (Ca2+-ATPase), sodium-potassium adenosine triphosphatase (Na+-K+-ATPase) and calcium-magnesium adenosine triphosphatase (Ca2+-Mg2+-ATPase) in the hippocampus were detected by commercial kits. Fura-2 pentakis(acetoxymethyl) (Fura-2/AM) probe and reactive oxygen species (ROS) reagent kit were used for measuring the concentration of Ca2+ and ROS in the hippocampus synapse, respectively. Rats exposed to B(a)P resulted in the deficits in the spatial memory manifested by the increased escape latency and decreased number of crossing platform and time spent in target quadrant in comparison with the control groups. Benzo(a)pyrene exposure caused the significant decrease in the ATPase activity in the hippocampus and caused Ca2+ overload in the synaptic, besides, the ROS concentration increased significantly which may further induce neurobehavioral impairment of the neonatal rats. Our findings suggest that postnatal B(a)P exposure may cause the neurobehavioral impairments in the neonatal rats, which were mediated by the decreased ATPase activity and elevated Ca2+ concentration. Int J Occup Med Environ Health 2017;30(2):203-211.

Characterization and validation of candidate reference methods for the determination of calcium and magnesium in biological fluids

Biological fluids monitoring is one of the important tools in prevention of diseases. Mineral elements in these media are essential factors to collaborate biological monitoring, disease conditions of humans, and maintenance of good health. These minerals are usually measured in laboratories using complicated and expensive techniques as ion chromatography (IC), atomic absorption spectroscopy (AAS), and inductive coupled plasma (ICP). The current work tries to validate alternative simpler and cheaper methods for the measurement of calcium (Ca2+) and magnesium (Mg2+) in the biological medium. Therefore, we had optimized EDTA titration, flame-atomic emission spectroscopy (FAES), and ion-selective electrode (ISE) to measure biological calcium. In addition, EDTA titration and ISE used to measure magnesium in biological samples. In fact, we are the first who totally validated cheapest analytical methods for the analyses of these cations in biological fluids. The influence of standard calibration curve on method imprecision and inaccuracy was examined using external and internal quality control materials. In general, the recoveries of the optimized methods were sufficiently good [92–103%]. Good stable reproducibility was registered especially with the lowest values of the relative standard deviation (RSD) of the ISE. Besides, good readabilities expressed as the limits of quantitation (LOQs) for Ca2+ measurements using FAES, ISE, and EDTA were (2.1–3.0mg/L), (3.1–6.1mg/L), and (3.9–7.7mg/L), respectively. In addition, the LOQs for Mg2+ measurements using ISE and EDTA were (1.2–4.5mg/L) and (2.0–5.7mg/L), respectively. Difference (%) of the reproducibility of the measurements in 5days and the uncertainty was in the following range: FAES (just for Ca2+) ISE EDTA. The validated methods showed acceptable correlations (0.9734–0.9990). They provided rapid, less tedious, practical and more accurate alternatives for the quantification of those bivalent cations in human fluids. Consequently, this research supports the implementation of cheap techniques and provides accurate analytical methods for the measurements of biological calcium and magnesium.