Virological evaluation of natural and modified attapulgite against porcine epidemic diarrhoea virus.

BACKGROUND: The Porcine Epidemic Diarrhea Virus (PEDV) has caused significant economic losses in the global swine industry. As a potential drug for treating diarrhea, the antiviral properties of attapulgite deserve further study. METHODS: In this study, various methods such as RT-qPCR, Western blot, viral titer assay, Cytopathic Effect, immunofluorescence analysis and transmission electron microscopy were used to detect the antiviral activity of attapulgite and to assess its inhibitory effect on PEDV. RESULTS: When exposed to the same amount of virus, there was a significant decrease in the expression of the S protein, resulting in a viral titer reduction from 10-5.613 TCID50/mL to 10-2.90 TCID50/mL, which represents a decrease of approximately 102.6 folds. Results of cytopathic effect and indirect immunofluorescence also indicate a notable decrease in viral infectivity after attapulgite treatment. Additionally, it was observed that modified materials after acidification had weaker antiviral efficacy compared to powdered samples that underwent ultrasonic disintegration, which showed the strongest antiviral effects. CONCLUSION: As a result, Attapulgite powders can trap and adsorb viruses to inhibit PEDV in vitro, leading to loss of viral infectivity. This study provides new materials for the development of novel disinfectants and antiviral additives.

Vibrio cholerae biofilm scaffolding protein RbmA shows an intrinsic, phosphate-dependent autoproteolysis activity.

Vibrio cholerae is the causative agent of the diarrheal disease cholera, for which biofilm communities are considered to be environmental reservoirs. In endemic regions, and after algal blooms, which may result from phosphate enrichment following agricultural runoff, the bacterium is released from biofilms resulting in seasonal disease outbreaks. However, the molecular mechanism by which V. cholerae senses its environment and switches lifestyles from the biofilm-bound state to the planktonic state is largely unknown. Here, we report that the major biofilm scaffolding protein RbmA undergoes autocatalytic proteolysis via a phosphate-dependent induced proximity activation mechanism. Furthermore, we show that RbmA mutants that are defective in autoproteolysis cause V. cholerae biofilms to grow larger and mechanically stronger, correlating well with the observation that RbmA stability directly affects microbial community homeostasis and rheological properties. In conclusion, our biophysical study characterizes a novel phosphate-dependent breakdown pathway of RbmA, while microbiological data suggest a new, sensory role of this biofilm scaffolding element.

Toward Tailoring the Degradation Rate of Magnesium-Based Biomaterials for Various Medical Applications: Assessing Corrosion, Cytocompatibility and Immunological Effects.

Magnesium (Mg)-based biomaterials hold considerable promise for applications in regenerative medicine. However, the degradation of Mg needs to be reduced to control toxicity caused by its rapid natural corrosion. In the process of developing new Mg alloys with various surface modifications, an efficient assessment of the relevant properties is essential. In the present study, a WE43 Mg alloy with a plasma electrolytic oxidation (PEO)-generated surface was investigated. Surface microstructure, hydrogen gas evolution in immersion tests and cytocompatibility were assessed. In addition, a novel in vitro immunological test using primary human lymphocytes was introduced. On PEO-treated WE43, a larger number of pores and microcracks, as well as increased roughness, were observed compared to untreated WE43. Hydrogen gas evolution after two weeks was reduced by 40.7% through PEO treatment, indicating a significantly reduced corrosion rate. In contrast to untreated WE43, PEO-treated WE43 exhibited excellent cytocompatibility. After incubation for three days, untreated WE43 killed over 90% of lymphocytes while more than 80% of the cells were still vital after incubation with the PEO-treated WE43. PEO-treated WE43 slightly stimulated the activation, proliferation and toxin (perforin and granzyme B) expression of CD8+ T cells. This study demonstrates that the combined assessment of corrosion, cytocompatibility and immunological effects on primary human lymphocytes provide a comprehensive and effective procedure for characterizing Mg variants with tailorable degradation and other features. PEO-treated WE43 is a promising candidate for further development as a degradable biomaterial.

Sintered and 3D-Printed Bulks of MgB2-Based Materials with Antimicrobial Properties.

Pristine high-density bulk disks of MgB2 with added hexagonal BN (10 wt.%) were prepared using spark plasma sintering. The BN-added samples are machinable by chipping them into desired geometries. Complex shapes of different sizes can also be obtained by the 3D printing of polylactic acid filaments embedded with MgB2 powder particles (10 wt.%). Our present work aims to assess antimicrobial activity quantified as viable cells (CFU/mL) vs. time of sintered and 3D-printed materials. In vitro antimicrobial tests were performed against the bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecium DSM 13590, and Enterococcus faecalis ATCC 29212; and the yeast strain Candida parapsilosis ATCC 22019. The antimicrobial effects were found to depend on the tested samples and microbes, with E. faecium being the most resistant and E. coli the most susceptible.

Neurotrophic Effect of Magnesium Comenate in Normal and under Conditions of Oxidative Stress in Culture of Chicken Spinal Ganglia.

The neurotrophic properties of magnesium comenate were studied under standard conditions and under conditions of oxidative stress. It was found that magnesium comenate has a stimulating effect on the neurotrophic processes of the spinal ganglia under normal conditions and under conditions of oxidative stress. Under standard conditions, magnesium comenate exhibits neurotrophic activity at a concentration of 0.0001 mM, under conditions of oxidative stress, magnesium comenate exhibits neurotrophic activity at concentration 0.1 mM.

Improved In Vitro Test Procedure for Full Assessment of the Cytocompatibility of Degradable Magnesium Based on ISO 10993-5/-12.

Magnesium (Mg)-based biomaterials are promising candidates for bone and tissue regeneration. Alloying and surface modifications provide effective strategies for optimizing and tailoring their degradation kinetics. Nevertheless, biocompatibility analyses of Mg-based materials are challenging due to its special degradation mechanism with continuous hydrogen release. In this context, the hydrogen release and the related (micro-) milieu conditions pretend to strictly follow in vitro standards based on ISO 10993-5/-12. Thus, special adaptions for the testing of Mg materials are necessary, which have been described in a previous study from our group. Based on these adaptions, further developments of a test procedure allowing rapid and effective in vitro cytocompatibility analyses of Mg-based materials based on ISO 10993-5/-12 are necessary. The following study introduces a new two-step test scheme for rapid and effective testing of Mg. Specimens with different surface characteristics were produced by means of plasma electrolytic oxidation (PEO) using silicate-based and phosphate-based electrolytes. The test samples were evaluated for corrosion behavior, cytocompatibility and their mechanical and osteogenic properties. Thereby, two PEO ceramics could be identified for further in vivo evaluations.

Regenerative Potential of Various Soft Polymeric Scaffolds in the Temporomandibular Joint Condyle.

PURPOSE: Biodegradable polymeric scaffolds have been used for tissue engineering approaches and can be used to regenerate temporomandibular joint (TMJ) tissues. Synthetic acellular polymeric poly(glycerol sebacate) (PGS) scaffolds and natural scaffolds made from gelatin are polymeric scaffold sponges that could provide a substrate for cell infiltration and remodeling. The authors studied the regenerative potential of these 2 scaffolds in addition to a bioactive signal, magnesium (Mg), in a novel fibrocartilage defect model in the goat mandibular condylar cartilage (MCC). Furthermore, in a departure from the pig model, the authors have started to develop the goat as a repeatable surgical model with easy access into the joint space in skeletally mature animals. MATERIALS AND METHODS: Bilateral osteochondral defects were created in the mandibular condyle of mature female Spanish Boer goats. A 1-mm diameter drill was used to create a trough defect on the articular surface. Four groups were evaluated: 1) an empty control without an implant, 2) PGS with Mg ions, 3) gelatin with Mg ions, and 4) gelatin with Mg ions and trimagnesium phosphate (TMP) powder. Goats were allowed to heal for 3 months, and then the tissues were harvested. RESULTS: The empty control group showed a thin fibrous layer growing within the defect. The PGS and gelatin sponge groups showed a cartilage layer with glycosaminoglycan and collagen type II and robust regeneration of the fibrous layer as exhibited by cell infiltration and collagen in the defect. TMP in the gelatin did not degrade and seemed to hamper healing. CONCLUSION: These results suggest that synthetic and natural sponges can provide a template for new tissue growth in the MCC of the TMJ. Furthermore, this study is the first to attempt to develop the goat as an in vivo TMJ tissue regeneration model.

Effects of different levels of modified palygorskite supplementation on the growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers.

This experiment was designed to investigate effects of different levels of modified palygorskite (MPal) supplementation on growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers. A total of 320 1-day-old Arbor Acres broilers were randomly assigned into 5 dietary treatments and fed a basal diet supplemented with 0, 0.25, 0.5, 1 and 2 g/kg MPal, respectively, for a 42-day feeding trial. Treatments quadratically reduced feed/gain ratio (F:G) during 1-21 days and linearly decreased average daily feed intake and F:G during 22-42 days, and linearly and quadratically decreased average daily feed intake and F:G during overall period (p < 0.05, 0.50 g/kg treatment showed the lowest F:G). MPal supplementation increased the contents of 21-day jejunal secretory immunoglobulin A (SIgA) quadratically, and 21-day jejunal immunoglobulin G (IgG), immunoglobulin M (IgM) and 42-day jejunal total superoxide dismutase (T-SOD) activity linearly and quadratically (0.50 g/kg treatment showed the highest immunoglobulin concentration), whereas linearly reduced 21-day ileal SIgA level and 42-day jejunal malondialdehyde (MDA) accumulation and serum diamine oxidase activity, and quadratically decreased 21-day ileal MDA level (p < 0.05). The 42-day jejunal SIgA, IgG and IgM concentrations, and T-SOD activity in jejunum at 21 days and ileum at both 21 days and 42 days were quadratically increased with MPal administration (p < 0.05, 0.50 g/kg treatment showed the highest T-SOD activity). The mucin 2 mRNA abundances in 42-day jejunum and 21-day ileum were quadratically increased with MPal supplementation (p < 0.05). Treatments linearly increased 42-day ileal zonula occludens-1, claudin-3 and jejunal claudin-3 mRNA level, whereas linearly and quadratically increased ileal claudin-2 mRNA level (p < 0.05). In conclusion, MPal supplementation exhibited beneficial effects on growth performance, intestinal immunity, antioxidant capacity and intestinal integrity and barrier function of broiler with its optimum dosage being 0.5 g/kg.

Comparison of four different fuller's earth formulations in skin decontamination.

Industrial accidents, wars and terrorist threats are potential sources of skin contamination by highly toxic chemical warfare agents and manufacturing compounds. We have compared the time-dependent adsorption capacity and decontamination efficiency of fuller's earth (FE) for four different formulations for the molecular tracer, 4-cyanophenol (4-CP), in vitro and ex vivo using water decontamination as standard. The adsorption capacity of FE was assessed in vitro for 4-CP aqueous solutions whereas decontamination efficiency was investigated ex vivo by tracking porcine skin 4-CP content using attenuated total reflectance Fourier transform infrared spectroscopy. Decontamination was performed on short time, exposed porcine skin to 4-CP by application of FE: (1) as free powder; (2) loaded on adhesive tape; (3) on powdered glove; or (4) in suspension. Removal rate of 4-CP from aqueous solutions correlates with the amount of FE and its contact time. Decontamination efficiency estimated by the percentage of 4-CP recovery from contaminated porcine skin, achieved 54% with water, ranged between ~60 and 70% with dry FE and reached ~90% with FE suspension. Successful decontamination of the FE suspension, enabling a dramatic reduction of skin contamination after a brief exposure scenario, appears to be rapid, reliable and should be formulated in a new device ready to use for self-application.

Dietary supplementation with the clay mineral palygorskite affects performance and beneficially modulates caecal microbiota in laying pullets.

AIMS: The objective of this study was twofold: (i) to examine the effect of early-posthatch dietary inclusion of the clay mineral palygorskite on laying pullets' growth and (ii) to determine the potential effects of the latter diet on caecal microbial communities. METHODS AND RESULTS: Four hundred and thirty-two female, 1-day-old Hyline Brown chickens were equally and randomly allocated to two dietary treatment groups; control and palygorskite (0 and 0·5% palygorskite respectively). They were reared in floor pens for 18 weeks. Feed intake, feed conversion ratio, body weight gain and uniformity were assessed. At the end of the rearing period, 53 birds per group were transferred to laying cages without any changes in their respective dietary treatments. At onset of lay, eight birds from each group were euthanized and their caeca were obtained for analysis. Culture-independent and sequencing-based methods were used to analyse caecal microbial composition. CONCLUSIONS: Palygorskite dietary supplementation increased the uniformity of the relative group at the end of the rearing period. Pullets that received palygorskite had different and more homogeneous caecal microbial profiles at onset of lay when compared to controls. Moreover, in the caeca of the former pullets a more favourable microbiota was evident; it comprised largely of bacteria that are major degraders of resistant polysaccharides and efficient in butyrate production. SIGNIFICANCE AND IMPACT OF THE STUDY: The novelty of this study lies to the beneficial effect of palygorskite (a clay mineral) to pullets growth and health, likely through modulation of the gut microbiota.

Preliminary evaluation of military, commercial and novel skin decontamination products against a chemical warfare agent simulant (methyl salicylate).

Rapid decontamination is vital to alleviate adverse health effects following dermal exposure to hazardous materials. There is an abundance of materials and products which can be utilised to remove hazardous materials from the skin. In this study, a total of 15 products were evaluated, 10 of which were commercial or military products and five were novel (molecular imprinted) polymers. The efficacies of these products were evaluated against a 10 µl droplet of (14)C-methyl salicylate applied to the surface of porcine skin mounted on static diffusion cells. The current UK military decontaminant (Fuller's earth) performed well, retaining 83% of the dose over 24 h and served as a benchmark to compare with the other test products. The five most effective test products were Fuller's earth (the current UK military decontaminant), Fast-Act® and three novel polymers [based on itaconic acid, 2-trifluoromethylacrylic acid and N,N-methylenebis(acrylamide)]. Five products (medical moist-free wipes, 5% FloraFree™ solution, normal baby wipes, baby wipes for sensitive skin and Diphotérine™) enhanced the dermal absorption of (14)C-methyl salicylate. Further work is required to establish the performance of the most effective products identified in this study against chemical warfare agents.

On the mechanism of phosphoenolpyruvate synthetase (PEPs) and its inhibition by sodium fluoride: potential magnesium and aluminum fluoride complexes of phosphoryl transfer.

Phosphoenolpyruvate synthase (PEPs) catalyzes the conversion of pyruvate to phosphoenolpyruvate (PEP) using a two-step mechanism invoking a phosphorylated-His intermediate. Formation of PEP is an initial step in gluconeogenesis, and PEPs is essential for growth of Escherichia coli on 3-carbon sources such as pyruvate. The production of PEPs has also been linked to bacterial virulence and antibiotic resistance. As such, PEPs is of interest as a target for antibiotic development, and initial investigations of PEPs have indicated inhibition by sodium fluoride. Similar inhibition has been observed in a variety of phospho-transfer enzymes through the formation of metal fluoride complexes within the active site. Herein we quantify the inhibitory capacity of sodium fluoride through a coupled spectrophotometric assay. The observed inhibition provides indirect evidence for the formation of a MgF3(-) complex within the enzyme active site and insight into the phospho-transfer mechanism of PEPs. The effect of AlCl3 on PEPs enzyme activity was also assessed and found to decrease substrate binding and turnover.

The structure-forming role of magnesium pyrophosphate in the formation of DNA-containing microparticles during PCR.

This work is devoted to studying the mechanisms of formation of DNA-containing microparticles (MPs) during PCR. It was found that pyrophosphate, a byproduct of DNA synthesis, and magnesium cations are required for their formation, as evidenced by the results of biochemical and electron microscopy studies.

Chronic administration of nicotine enhances NMDA-activated currents in the prefrontal cortex and core part of the nucleus accumbens of rats.

Nicotine is an addictive substance of tobacco. It has been suggested that nicotine acts on glutamatergic (N-methyl-d-aspartate, NMDA) neurotransmission affecting dopamine release in the mesocorticolimbic system. This effect is reflected in neuroadaptative changes that can modulate neurotransmission in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) core (cNAcc) and shell (sNAcc) regions. We evaluated the effect of chronic administration of nicotine (4.23 mg/kg/day for 14 days) on NMDA activated currents in dissociated neurons from the PFC, and NAcc (from core and shell regions). We assessed nicotine blood levels by mass spectrophotometry and we confirmed that nicotine increases locomotor activity. An electrophysiological study showed an increase in NMDA currents in neurons from the PFC and core part of the NAcc in animals treated with nicotine compared to those of control rats. No change was observed in neurons from the shell part of the NAcc. The enhanced glutamatergic activity observed in the neurons of rats with chronic administration of nicotine may explain the increased locomotive activity also observed in such rats. To assess one of the possible causes of increased NMDA currents, we used magnesium, to block NMDA receptor that contains the NR2B subunit. If there is a change in percent block of NMDA currents, it means that there is a possible change in expression of NMDA receptor subunits. Our results showed that there is no difference in the blocking effect of magnesium on the NMDA currents. The magnesium lacks of effect after nicotinic treatment suggests that there is no change in expression of NR2B subunit of NMDA receptors, then, the effect of nicotine treatment on amplitude of NMDA currents may be due to an increase in the quantity of receptors or to a change in the unitary conductance, rather than a change in the expression of the subunits that constitute it.

Magnesium modulates parathyroid hormone secretion and upregulates parathyroid receptor expression at moderately low calcium concentration.

BACKGROUND: The interest on magnesium (Mg) has grown since clinical studies have shown the efficacy of Mg-containing phosphate binders. However, some concern has arisen for the potential effect of increased serum Mg on parathyroid hormone (PTH) secretion. Our objective was to evaluate the direct effect of Mg in the regulation of the parathyroid function; specifically, PTH secretion and the expression of parathyroid cell receptors: CaR, the vitamin D receptor (VDR) and FGFR1/Klotho. METHODS: The work was performed in vitro by incubating intact rat parathyroid glands in different calcium (Ca) and Mg concentrations. RESULTS: Increasing Mg concentrations from 0.5 to 2 mM produced a left shift of PTH-Ca curves. With Mg 5 mM, the secretory response was practically abolished. Mg was able to reduce PTH only if parathyroid glands were exposed to moderately low Ca concentrations; with normal-high Ca concentrations, the effect of Mg on PTH inhibition was minor or absent. After 6-h incubation at a Ca concentration of 1.0 mM, the expression of parathyroid CaR, VDR, FGFR1 and Klotho (at mRNA and protein levels) was increased with a Mg concentration of 2.0 when compared with 0.5 mM. CONCLUSIONS: Mg reduces PTH secretion mainly when a moderate low calcium concentration is present; Mg also modulates parathyroid glands function through upregulation of the key cellular receptors CaR, VDR and FGF23/Klotho system.

Cytocompatibility evaluation of different biodegradable magnesium alloys with human mesenchymal stem cells.

In the last few years, the use of biodegradable magnesium (Mg) alloys has evoked great interest in the orthopedic field due to great advantages over long-term implant materials associated with various side effects like allergy and sensitization and consequent implant removal surgeries. However, degradation of these Mg alloys results in ion release, which may cause severe cytotoxicity and undesirable complications after implantation. In this study, we investigated the cytological effects of various Mg alloys on cells that play an important role in bone repair. Eight different magnesium alloys containing varying amounts of Al, Zn, Nd and Y were either incubated directly or indirectly with the osteosarcoma cell line Saos-2 or with uninduced and osteogenically-induced human mesenchymal stem cells (MSCs) isolated from bone marrow specimens obtained from the femoral shaft of patients undergoing total hip replacement. Cell viability, cell attachment and the release of ions were investigated at different time points in vitro. During direct or indirect incubation different cytotoxic effects of the Mg alloys on Saos-2 cells and osteogenically-induced or uninduced MSCs were observed. Furthermore, the concentration of degradation products released from the Mg alloys differed. Overall, Mg alloys MgNd2, MgY4, MgAl9Zn1 and MgY4Nd2 exhibit good cytocompatibility. In conclusion, this study reveals the necessity of cytocompatibility evaluation of new biodegradable magnesium alloys with cells that will get in direct contact to the implant material. Furthermore, the use of standardized experimental in vitro assays is necessary in order to reliably and effectively characterize new Mg alloys before performing in vivo experiments.

Influence of fluoride treatment on surface properties, biodegradation and cytocompatibility of Mg-Nd-Zn-Zr alloy.

Fluoride treatment is a commonly used technique or pre-treatment to optimize the degradation kinetic and improve the biocompatibility of magnesium-based implant. The influence of changed surface properties and degradation kinetics on subsequent protein adsorption and cytocompatibility is critical to understand the biocompatibility of the implant. In this study, a patent magnesium alloy Mg-Nd-Zn-Zr alloy (JDBM) designed for cardiovascular stent application was treated by immersion in hydrofluoric acid. A 1.5 µm thick MgF2 layer was prepared. The surface roughness was increased slightly while the surface zeta potential was changed to a much more negative value after the treatment. Static contact angle test was performed, showing an increase in hydrophilicity and surface energy after the treatment. The MgF2 layer slowed down in vitro degradation rate, but lost the protection effect after 10 days. The treatment enhanced human albumin adsorption while no difference of human fibrinogen adsorption amount was observed. Direct cell adhesion test showed many more live HUVECs retained than bare magnesium alloy. Both treated and untreated JDBM showed no adverse effect on HUVEC viability and spreading morphology. The relationship between changed surface characteristics, degradation rate and protein adsorption, cytocompatibility was also discussed.

Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.

Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.

Protective effect of magnesium nitrate against neurological disorders provoked by cerebral ischemia in rats.

The study examined effects of inorganic magnesium agents: magnesium nitrate Mg(NO3)2, magnesium sulfate MgSO4, and magnesium chloride MgCl2 on the development of neurological disorders and mortality in rats resulting from cerebral ischemia provoked by a single-stage bilateral occlusion of the common carotid arteries. The rats were injected with one of examined magnesium preparations (5 mg/1 kg body weight) 1 h prior to or 1-2 sec after occlusion. The control group rats were treated with physiological saline at the same terms. Irrespective of the moment of injection, magnesium nitrate demonstrated significant protective effect on dynamics of neurological disorders and mortality, while similar effects of magnesium sulfate and magnesium chloride were insignificant.

[Effects of magnesium on the onset time of rocuronium in patients for cesarean delivery].

BACKGROUND: Although magnesium can potentially shorten onset time of a muscle relaxant, it is unclear whether it does shorten the onset time of rocuronium for patients in cesarean delivery (CD). Thus the purpose of this study is to compare the onset time of rocuronium in patients with or without preoperative magnesium treatment. METHODS: In 9 CD patients without magnesium (CD group) and 8 CD patients with magnesium (CD-Mg group), neuromuscular function was continuously assessed with acceleromyography immediately after induction of general anesthesia with intravenous injection of thiopental (4-5 mg x kg(-1)) and rocuronium (0.6 mg x kg(-1)). Onset time of muscle relaxation, defined by the time from rocuronium bolus injection until complete absence of twitch height, was measured. RESULTS: The onset time of both groups did not significantly differ (50 +/- 10 seconds vs. 51 +/- 11 seconds; P = 0.93, unpaired t-test). Median magnesium concentration, 5.2 mg x dl(-1) (3.8-6.3), and the onset time of CD-Mg group did not correlate magnesium concentrations (P = 0.23, Pearson's correlation coefficient test). CONCLUSIONS: Magnesium did not shorten the onset time of rocuronium 0.6 mg x kg(-1) in CD patients.