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PubMed2005

Success of mineral trioxide aggregate in pulpotomized primary molars.

UNLABELLED: The aim of the present study was to compare, clinically and radiographically, the mineral trioxide aggregate (MTA) to formocresol (FC) when used as medicaments in pulpotomized vital human primary molars. METHODS: The sample consisted of 120 primary molars, all teeth were treated with the same conventional pulpotomy technique. Sixty molars received FC and 60 received MTA throughout a random selection technique. RESULTS: At the end of 24-month evaluation period, 74 molars (36 FC, 38 MTA) were available for clinical and radiographic evaluation. None of the MTA treated teeth showed any clinical or radiographic pathology, while the FC group showed a success rate of 86.8% radiographically and 98.6% clinically. The difference between the two groups in the radiographic outcomes was statistically significant. It was concluded that MTA treated molars demonstrated significantly greater success. MTA seems to be a suitable replacement for formocresol in pulpotomized primary teeth.

Aluminum Compounds↗
PubMed2006

Characterization of phosphorus species in biosolids and manures using XANES spectroscopy.

Identification of the chemical P species in biosolids or manures will improve our understanding of the long-term potential for P loss when these materials are land applied. The objectives of this study were to determine the P species in dairy manures, poultry litters, and biosolids using X-ray absorption near-edge structure (XANES) spectroscopy and to determine if chemical fractionation techniques can provide useful information when interpreted based on the results of more definitive P speciation studies. Our XANES fitting results indicated that the predominant forms of P in organic P sources included hydroxylapatite, PO(4) sorbed to Al hydroxides, and phytic acid in lime-stabilized biosolids and manures; hydroxylapatite, PO(4) sorbed on ferrihydrite, and phytic acid in lime- and Fe-treated biosolids; and PO(4) sorbed on ferrihydrite, hydroxylapatite, beta-tricalcium phosphate (beta-TCP), and often PO(4) sorbed to Al hydroxides in Fe-treated and digested biosolids. Strong relationships existed between the proportions of XANES PO(4) sorbed to Al hydroxides and NH(4)Cl- + NH(4)F-extractable P, XANES PO(4) sorbed to ferrihydrite + phytic acid and NaOH-extractable P, and XANES hydroxylapatite + beta-TCP and dithionite-citrate-bicarbonate (DCB)- + H(2)SO(4)-extractable P (r(2) = 0.67 [P = 0.01], 0.78 [P = 0.01], and 0.89 [P = 0.001], respectively). Our XANES fitting results can be used to make predictions about long-term solubility of P when biosolids and manures are land applied. Fractionation techniques indicate that there are differences in the forms of P in these materials but should be interpreted based on P speciation data obtained using more advanced analytical tools.

Absorption↗
PubMed2000

Mineral trioxide aggregate (MTA) as a root end filling material in apical surgery--a case report.

Many root end filling materials for apical surgeries have been identified either for scientific evaluation or clinical usage but none meets the requirements of an ideal root end filling material. Recently a new cement, Mineral Trioxide Aggregate (MTA) was researched as a potential root end filling material and showed promising results. This paper reports the significant findings of research done on MTA as a root end filling material and presents a clinical case where apical surgery was performed using MTA as retrograde filling.

Aluminum Compounds↗
PubMed2002

Reaction of rat connective tissue to implanted dentin tubes filled with a white mineral trioxide aggregate.

The purpose of this paper was to study the reaction of rat subcutaneous connective tissue to the implantation of dentin tubes filled with white mineral trioxide aggregate (MTA), a material that will be marketed. The tubes were implanted into rat subcutaneous tissue and the animals were sacrificed after 7 and 30 days. The undecalcified pieces were prepared for histological analysis with polarized light and von Kossa technique for mineralized tissues. Granulations birefringent to polarized light and an irregular structure like a bridge were observed next to the material; both were von Kossa positive. Also, in the dentin wall tubules a layer of birefringent granulations was observed. The results were similar to those reported for gray MTA, indicating that the mechanisms of action of the white and gray MTA are similar.

Aluminum Compounds↗
PubMed2003

Non-surgical post perforation repair with mineral trioxide aggregate: a case report.

Mineral trioxide aggregate, or MTA, is a biocompatible material that has demonstrated numerous clinical applications in endodontics. It appears to be an improvement over other materials for use in procedures that involve root repair and bone healing, as it has consistently demonstrated the ability to promote regeneration of the original tissues when it is placed in contact with the periradicular tissues. This article describes the use of MTA for the successful non-surgical repair of an iatrogenic post perforation.

Adult↗
PubMed2000

Calcium sensitivity enhancers.

Patients suffering from acute decompensated heart failure, immediately after infarction, or late in the progression of heart failure, need short-term, positive inotropic support in their therapy. To date, drugs acting through cAMP are used to increase the contractile force of the heart of such patients, although it is well-known that these kind of drugs may trigger arrhythmias and as a result may worsen the long-term prognosis of the patients. Recently, levosimendan, a new drug acting through calcium sensitization of contractile proteins, has shed new light on inotropic therapy, and, importantly, has reduced mortality in acute heart failure patients. For this reason, this review focuses on calcium sensitizers and the mechanisms behind calcium sensitization. The compounds which have been selected for detailed consideration are limited only to positive inotropic compounds that produce calcium sensitization of contractile proteins. In addition, this review elucidates the differences between various calcium sensitizing mechanisms, and mainly focuses on the relaxation of cardiac muscle.

Journal Article↗
PubMed2006

[Kinetic analysis of additive effect on desulfurization activity].

The additive effects of A12O3, Fe2O3 and MnCO3 on CaO sulfation kinetics were investigated by thermogravimetic analysis method and modified grain model. The activation energy (Ea) and the pre-exponential factor (k0) of surface reaction, the activation energy (Ep) and the pre-exponential factor (D0) of product layer diffusion reaction were calculated according to the model. Additions of MnCO3 can enhance the initial reaction rate, product layer diffusion and the final CaO conversion of sorbents, the effect mechanism of which is similar to that of Fe2O3. The method based isokinetic temperature Ts and activation energy can not estimate the contribution of additive to the sulfation reactivity, the rate constant of the surface reaction (k), and the effective diffusivity of reactant in the product layer (Ds) under certain experimental conditions can reflect the effect of additives on the activation. Unstoichiometric metal oxide may catalyze the surface reaction and promote the diffusivity of reactant in the product layer by the crystal defect and distinct diffusion of cation and anion. According to the mechanism and effect of additive on the sulfation, the effective temperature and the stoichiometric relation of reaction, it is possible to improve the utilization of sorbent by compounding more additives to the calcium-based sorbent.

Air Pollution↗
PubMed1995

Dotarizine versus flunarizine as calcium antagonists in chromaffin cells.

1. Dotarizine is a novel piperazine derivative structurally related to flunarizine that is currently being evaluated in clinical trials for its antimigraine and antivertigo effects. This clinical profile may be related to its Ca2+ antagonist properties. Therefore, the actions of both compounds as calcium antagonists were compared in bovine chromaffin cells. 2. Dotarizine and flunarizine blocked 45Ca2+ uptake into K+ depolarized chromaffin cells (70 mM K+/0.5 mM Ca2+ for 60 s) in a concentration-dependent manner, with IC50s of 4.8 and 6.7 microM, respectively. 3. Dotarizine and flunarizine also inhibited the whole-cell Ca2+ and Ba2+ currents (ICa, IBa) in voltage-clamped chromaffin cells, induced by depolarizing test pulses to 0 mV, during 50 ms, from a holding potential of -80 mV. Blockade exhibited IC50s of 4 microM for dotarizine and 2.2 microM for flunarizine. Dotarizine increased the rate of inactivation of ICa and IBa; inhibition of whole-cell currents was use-dependent. 4. Transient increases of the cytosolic Ca2+ concentration, [Ca2+]i, produced by K+ stimulation (70 mM K+ for 5 s) of single fura-2-loaded chromaffin cells, were also inhibited by dotarizine and flunarizine with IC50s of 1.2 and 0.6 microM, respectively. Upon washout of dotarizine, the [Ca2+]i increases recovered fully after 5-10 min. In contrast, the responses remained largely inhibited 10 min after washing out flunarizine. 5. Catecholamine release induced by K+ stimulation (10-s pulses of 70 mM) was inhibited by dotarizine with an IC50 of 2.6 microM and by flunarizine with an IC50 of 1.2 microM. The blocking effects of both compounds developed slowly, and was fully established after 20-30 min of superfusion. While blockade by dotarizine quickly reversed upon its washout, that of flunarizine lasted even 25 min after washing out.6. Catecholamine release from electroporated chromaffin cells triggered by 10 micro M Ca2+ was not affected by 10 micro M dotarizine or flunarizine.7. Overall, the results suggest that dotarizine behaves as a Ca2+ antagonist in bovine chromaffin cells. It exhibits a potency similar to flunarizine in blocking Ca2+ entry, Ca2+ channels, Cai2+ signals and secretion. The dotarizine effects are readily reversible suggesting that in contrast to flunarizine, it does not accumulate in cells. Dotarizine is devoid of intracellular effects on the secretory machinery. All its blocking effects on Ca2+ entry, [Ca2+]i rise and secretion are probably due to blockade of various Ca2+channel subtypes in chromaffin cells. This blockade is use-dependent and seems to be due to the increase by dotarizine of the rate of Ca2+ channel inactivation.

Animals↗
PubMed1999

Photolytic manipulation of [Ca2+]i reveals slow kinetics of potassium channels underlying the afterhyperpolarization in hippocampal pyramidal neurons.

The identity of the potassium channel underlying the slow, apamin-insensitive component of the afterhyperpolarization current (sIAHP) remains unknown. We studied sIAHP in CA1 pyramidal neurons using simultaneous whole-cell recording, calcium fluorescence imaging, and flash photolysis of caged compounds. Intracellular calcium concentration ([Ca2+]i) peaked earlier and decayed more rapidly than sIAHP. Loading cells with low concentrations of the calcium chelator EGTA slowed the activation and decay of sIAHP. In the presence of EGTA, intracellular calcium decayed with two time constants. When [Ca2+]i was increased rapidly after photolysis of DM-Nitrophen, both apamin-sensitive and apamin-insensitive outward currents were activated. The apamin-sensitive current activated rapidly (<20 msec), whereas the apamin-insensitive current activated more slowly (180 msec). The apamin-insensitive current was reduced by application of serotonin and carbachol, confirming that it was caused by sIAHP channels. When [Ca2+]i was decreased rapidly via photolysis of diazo-2, the decay of sIAHP was similar to control (1. 7 sec). All results could be reproduced by a model potassium channel gated by calcium, suggesting that the channels underlying sIAHP have intrinsically slow kinetics because of their high affinity for calcium.

Animals↗