Vehicle influence on calcium hydroxide pastes diffusion in human and bovine teeth

The purpose of this study was to compare the pH and calcium ion liberation after use of calcium hydroxide pastes with different paste vehicles in human or bovine teeth. Ninety-two single-rooted human and bovine roots were used. The roots were instrumented and an external cavity preparation was performed. The roots were divided in to human and bovine groups. Each group was subdivided into four subgroups (SB) according to the vehicle:SB1, detergent; SB2, saline; SB3, polyethylenoglycol + camphorated paramonochlorophenol (Calen PMCC) and SB4, polyethylenoglycol + furacyn paramonochlorophenol (FPMC). Specimens were immersed into saline solution at 37 degrees C and after 7 and 14 days pH and calcium ion measurements were made. The results were analyzed by ANOVA and Tukey tests (P < 0.05). There was no statistical difference between bovine and human teeth in the pH analysis (P < 0.05), but bovine teeth provided larger calcium ion liberation than human teeth. Calen PMCC was statistically more effective for pH increase and calcium ion liberation in all analyses, followed by FPMC and saline. Detergent showed the lowest pH alterations and calcium ion liberation. The period of 14 days showed more calcium ionic liberation than the 7-day period.

Hypertrophied myocardium is more dependent on extracellular calcium than the normal cardiac muscle

Background: The aim of this study was to analyze stable hypertrophied myocardial function and its response to inotropic maneuvers in rats submitted to renovascular hypertension for a 10-week period (RHT group, n=10). Material/Methods: Myocardial performance was studied in isolated left ventricle papillary muscles in isometric contraction under the following conditions: at postrest contraction of 30 seconds (PRC), at extracellular calcium (ECa 2+) chloride concentration of 1.25 and 5.20 mM, and after beta-adrenergic stimulation with 10 -6 M isoproterenol (ISOP). Results: The results were compared with normotensive Wistar controls rats (C group, n=10). In basal condition, resting tension, and contraction time (TPT) were greater, while relaxation time (RT 50) tended to be longer in RHT than C group. PRC and ISOP promoted a similar change in muscle function response intensity (Δ) in both groups. ECa 2+ shift did not change TPT in the C group and decreased TPT in the RHT animals; Δ was different between these groups. RT 50 increased in C and decreased in RHT, both without statistical significance; however, Δ was different. Conclusions: These results suggest that hypertrophied myocardial dysfunction may be attibuted to changes in intracellular calcium cycling. © Med Sci Monit, 2010.

Effects of calcium hydroxide addition on the physical and chemical properties of a calcium silicate-based sealer

Recently, various calcium silicate-based sealers have been introduced for use in root canal filling. The MTA Fillapex is one of these sealers, but some of its physicochemical properties are not in accordance with the ISO requirements. Objective: The aim of this study was to evaluate the flowability, pH level and calcium release of pure MTA Fillapex (MTAF) or containing 5% (MTAF5) or 10% (MTAF10) calcium hydroxide (CH), in weight, in comparison with AH Plus sealer. Material and Methods: The flowability test was performed according to the ISO 6876: 2001 requirements. For the pH level and calcium ion release analyses, the sealers were placed individually (n=10) in plastic tubes and immersed in deionized water. After 24 hours, 7 and 14 days, the water in which each specimen had been immersed was evaluated to determine the pH level changes and calcium released. Flowability, pH level and calcium release data were analyzed statistically by the ANOVA test (alpha=5%). Results: In relation to flowability: MTAF>AH Plus>MTAF5>MTAF10. In relation to the pH level, for 24 h: MTAF5=MTAF10=MTAF>AH Plus; for 7 and 14 days: MTAF5=MTAF10>MTAF>AH Plus. For the calcium release, for all periods: MTAF>MTAF5=MTAF10>AH Plus. Conclusions: The addition of 5% CH to the MTA Fillapex (in weight) is an alternative to reduce the high flowability presented by the sealer, without interfering in its alkalization potential.

Permethrin chronic exposure alters motor coordination in rats: Effect of calcium supplementation and amlodipine

Recently was observed that pyrethroids decrease motor coordination and that calcium channels can be important targets for this effect. To contribute with this observation, this work studied the motor coordination and exploration (using hole-board apparatus), and locomotion (using open-field apparatus) of rats exposed to following treatments: permethrin (PM), PM plus calcium gluconate (CG) and PM plus amlodipine (AML). The results obtained show that CG or AML alone not changed the motor coordination while PM decreases it. CG kept the effect of permethrin; AML, however, decreased the values of permethrin to the control. Locomotor activity and exploration, which could confound results of motor coordination, were not modified by treatments. The concentration of PM in brain tissue was increased by the CG and AML. The neurosomatic index (weight brain/body weight) was increased by the PM and PM + CG. In conclusion, the combined results here obtained indicates that the calcium ion and the channels in which it is involved can be important targets for the toxic effect of pyrethroid insecticide permethrin on motor nerve activity of rats. (c) 2014 Elsevier B.V. All rights reserved.

Effects of coronal leakage on concentration of hydrogen ions and calcium hydroxide release of several calcium hydroxide pastes over different periods of time

Purpose: To evaluate the effects of coronal leakage on concentration of hydrogen ions (pH) and calcium release of several calcium hydroxide pastes, over different periods of time. Material and Methods: Fifty extracted human mandibular central incisors (n=10) were instrumented up to the F2 instrument and assigned to the following intracanal dressing: G1- Calen, G2- Calen with 0.4% chlorhexidine (CHX), G3- Calcium hydroxide with camphorated paramonochlorophenol (CPMC) and glycerin, G4- Calen, but temporary filling material maintained during all test (positive control) and G5- Root canal without intracanal dressing (negative control). All groups were immersed in distilled water for 7 days. In sequence, the temporary filling materials were removed, except in controls groups. All specimens were individually mounted on a specific device and only its root again immersed in distilled water. Concentration of hydrogen ions and calcium release by calcium hydroxide pastes in distilled water were evaluated in 24h, 7, 14 and 28 days. The results were submitted to ANOVA test (p = 0.05). After 28 days, root canals from experimental groups were examined in SEM. Results: G1, G2, G3 and G4 presented similar pH values and calcium release and did not differ from each other (p>0.05), up to 7 days. After this time G1, G2 and G3 presented values lower values than G4 (p<0.05). In SEM analysis, calcium hydroxide residues were observed in all experimental groups. Conclusions: After 7 days, coronal leakage decreased the concentration of hydrogen ions and calcium ion release provided by all calcium hydroxide pastes.

Niobium pentoxide as radiopacifying agent of calcium silicate-based material: evaluation of physicochemical and biological properties

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cytocompatibility of Porous Biphasic Calcium Phosphate Granules With Human Mesenchymal Cells by a Multiparametric Assay

This work aims to evaluate the cytocompatibility of injectable and moldable restorative biomaterials based on granules of dense or porous biphasic calcium phosphates (BCPs) with human primary mesenchymal cells, in order to validate them as tools for stem cell-induced bone regeneration. Porous hydroxyapatite (HA) and HA/beta-tricalcium phosphate (beta-TCP) (60: 40) granules were obtained by the addition of wax spheres and pressing at 20 MPa, while dense materials were compacted by pressing at 100 MPa, followed by thermal treatment (1100 degrees C), grinding, and sieving. Extracts were prepared by 24-h incubation of granules on culture media, with subsequent exposition of human primary mesenchymal cells. Three different cell viability parameters were evaluated on the same samples. Scanning electron microscopy analysis of the granules revealed distinct dense and porous surfaces. After cell exposition to extracts, no significant differences on mitochondrial activity (2,3-bis(2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) or cell density (Crystal Violet Dye Elution) were observed among groups. However, Neutral Red assay revealed that dense materials extracts induced lower levels of total viable cells to porous HA/beta-TCP (P < 0.01). Calcium ion content was also significantly lower on the extracts of dense samples. Porogenic treatments on BCP composites do not affect cytocompatibility, as measured by three different parameters, indicating that these ceramics are well suited for further studies on future bioengineering applications.

Temperature dependent growth and inorganic ion composition of haemolymph of juvenile Sepia officinalis, 2006

B Body wet weight and mantle length of juvenile Sepia officinalis were monitored over a peroid of five weeks. The animals had hatched in our aquarium system in Bremerhaven, Germany at 16°C and were descendants of individuals collected in the Oosterschelde estuary, Netherlands. Animals were kept in natural sea water at 10 or 17°C and fed small live shrimp (Palaemonetes varians) ad libitum daily. At the end of the experiment some animals kept at 17°C were sacrificed using ethanol. Haemolymph was withdrawn from the head vein using syringe and needle. Haemolymph samples were stored at -20°C until Na+, Cl-, K+, Mg2+, Ca2+ and SO42- concentrations were determined using ion chromatography. Mean body weight more that tripled at 17°C during the investigation period, while growth was impared by exposue to 10°C. Haemolymph ion concentrations were similar to those in sea water, except for sulphate. The concentration of this ion in the haemolymph was more that ten times lower than in sea water.

Haemolymph inorganic ion composition, physiology and behaviour dependent on temperature and ambient magnesium concentration in early life history stages of Paralomis granulosa (Decapoda, Anomura, Lithodidae)

Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (-1.8 °C) Antarctic continental shelf, but caridean shrimps are abundant. This has at least partly been attributed to low capacities for magnesium excretion in brachyuran and anomuran lithodid crabs ([Mg2+]HL = 20-50 mmol/L) compared to caridean shrimp species ([Mg2+]HL = 5-12 mmol/L). Magnesium has an anaesthetizing effect and reduces cold tolerance and activity of adult brachyuran crabs. We investigated whether the capacity for magnesium regulation is a factor that influences temperature-dependent activity of early ontogenetic stages of the Sub-Antarctic lithodid crab Paralomis granulosa. Ion composition (Na+, Mg2+, Ca2+, Cl-, [SO4]2-) was measured in haemolymph withdrawn from larval stages, the first and second juvenile instars (crabs I and II) and adult males and females. Magnesium excretion improved during ontogeny, but haemolymph sulphate concentration was lowest in the zoeal stages. Neither haemolymph magnesium concentrations nor Ca2+:Mg2+ ratios paralleled activity levels of the life stages. Long-term (3 week) cold exposure of crab I to 1 °C caused a significant rise of haemolymph sulphate concentration and a decrease in magnesium and calcium concentrations compared to control temperature (9 °C). Spontaneous swimming activity of the zoeal stages was determined at 1, 4 and 9 °C in natural sea water (NSW, [Mg2+] = 51 mmol/L) and in sea water enriched with magnesium (NSW + Mg2+, [Mg2+] = 97 mmol/L). It declined significantly with temperature but only insignificantly with increased magnesium concentration. Spontaneous velocities were low, reflecting the demersal life style of the zoeae. Heart rate, scaphognathite beat rate and forced swimming activity (maxilliped beat rate, zoea I) or antennule beat rate (crab I) were investigated in response to acute temperature change (9, 6, 3, 1, -1 °C) in NSW or NSW + Mg2+. High magnesium concentration reduced heart rates in both stages. The temperature-frequency curve of the maxilliped beat (maximum: 9.6 beats/s at 6.6 °C in NSW) of zoea I was depressed and shifted towards warmer temperatures by 2 °C in NSW + Mg2+, but antennule beat rate of crab I was not affected. Magnesium may therefore influence cold tolerance of highly active larvae, but it remains questionable whether the slow-moving lithodid crabs with demersal larvae would benefit from an enhanced magnesium excretion in nature.

Haemolymph inorganic ion composition, physiology and behaviour dependent on temperature and magnesium in adult Paralomis granulosa (Decapoda, Anomura, Lithodidae)

A low capacity for regulation of extracellular Mg2+ has been proposed to exclude reptant marine decapod crustaceans from temperatures below 0°C and thus to exclude them from the high Antarctic. To test this hypothesis and to elaborate the underlying mechanisms in the most cold-tolerant reptant decapod family of the sub-Antarctic, the Lithodidae, thermal tolerance was determined in the crab Paralomis granulosa (Decapoda, Anomura, Lithodidae) using an acute stepwise temperature protocol (-1°, 1°, 4°, 7°, 10°, and 13°C). Arterial and venous oxygen partial pressures (Po2) in hemolymph, heartbeat and ventilation beat frequencies, and hemolymph cation composition were measured at rest and after a forced activity (righting) trial. Scopes for heartbeat and ventilation beat frequencies and intermittent heartbeat and scaphognathite beat rates at rest were evaluated. Hemolymph [Mg2+] was experimentally reduced from 30 mmol/L to a level naturally observed in Antarctic caridean shrimps (12 mmol/L) to investigate whether the animals remain more active and tolerant to cold (-1°, 1°, and 4°C). In natural seawater, righting speed was significantly slower at -1° and 13°C, compared with acclimation temperature (4°C). Arterial and venous hemolymph Po2 increased in response to cooling even though heartbeat and ventilation beat frequencies as well as scopes decreased. At rest, ionic composition of the hemolymph was not affected by temperature. Activity induced a significant increase in hemolymph [K+] at -1° and 1°C. Reduction of hemolymph [Mg2+] did not result in an increase in activity, an increase in heartbeat and ventilation beat frequencies, or a shift in thermal tolerance to lower temperatures. In conclusion, oxygen delivery in this cold-water crustacean was not acutely limiting cold tolerance, and animals may have been constrained more by their functional capacity and motility. In contrast to earlier findings in temperate and subpolar brachyuran crabs, these constraints remained insensitive to changing Mg2+ levels.

Ion concentrations and extracelluar pH of Calanus glacialis in Billefjorden, Svalbard

Arctic shelf zooplankton communities are dominated by the copepod Calanus glacialis. This species feeds in surface waters during spring and summer and accumulates large amounts of lipids. Autumn and winter are spent in dormancy in deeper waters. Lipids are believed to play a major role in regulating buoyancy, however, they cannot explain fine-tuning of the depth distribution. To investigate whether ion exchange processes and acid-base regulation support ontogenetic migration as suggested for Antarctic copepods, we sampled C. glacialis in monthly intervals for 1 yr in a high-Arctic fjord and determined cation concentrations and the extracellular pH (pHe) in its hemolymph. During the winter/spring transition, prior to the upward migration of the copepods, Li+ ions were exchanged with cations (Na+, Mg2+, and Ca2+) leading to Li+ concentrations of 197 mmol/L. This likely decreased the density and promoted upward migration in C. glacialis. Our data thus suggest that Li+ has a biological function in this species. Ion and pHe regulation in the hemolymph were not directly correlated, but the pHe revealed a seasonal pattern and was low (5.5) in winter and high (7.9) in summer. Low pHe during overwintering might be related to metabolic depression and thus, support diapause.

Haemolymph inorganic ion composition of crustaceans from the Southern Ocean

Brachyuran and anomuran decapod crabs do not occur in the extremely cold waters of the Antarctic continental shelf whereas caridean and other shrimp-like decapods, amphipods and isopods are highly abundant. Differing capacities for extracellular ion regulation, especially concerning magnesium, have been hypothesised to determine cold tolerance and by that the biogeography of Antarctic crustaceans. Magnesium is known to have a paralysing effect, which is even more distinct in the cold. As only few or no data exist on haemolymph ionic composition of Sub-Antarctic and Antarctic crustaceans, haemolymph samples of 12 species from these regions were analysed for the concentrations of major inorganic ions (Na+, K+, Ca2+, Mg2+, Cl-, SO4 2-) by ion chromatography. Cation relationships guaranteed neuromuscular excitability in all species. Sulphate and potassium correlated positively with magnesium concentration. The Antarctic caridean decapod as well as the amphipods maintained low (6-20% of ambient sea water magnesium concentration), Sub-Antarctic brachyuran and anomuran crabs as well as the Antarctic isopods high (54-96% of ambient sea water magnesium concentration) haemolymph magnesium levels. In conclusion, magnesium regulation may explain the biogeography of decapods, but not that of the peracarids.