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PubMed2006

Improvement of dewatering capacity of a petrochemical sludge.

Oily sludge produced from a petrochemical industry was used to investigate the improvement of its dewatering properties. The oil content (OC) and the dry solid content (DS) of the raw sludge were respectively, 15% and 3.6% by weight. The capillary suction time (CST) and the specific resistance to filtration (SRF) of the raw petrochemical industrial sludge were found to be 2000s and approximately 5.5x10(16)m/kg, respectively. Conventional chemical conditioners such as alum, lime, and polyelectrolyte, and less conventional ones like fly ash, gypsum, and bentonite were used in the sludge conditioning studies. Conventional chemical conditioners gave better results for the enhancement of the dewatering capacity of the sludge. The best result was obtained by using 0.9% cationic polyelectrolyte by weight, and a decrease of 99%-95% were achieved for CST and SRF, respectively, when this dosage of cationic polyelectrolyte was used.

Alum Compounds↗
PubMed2005

Advances since the paper by Zander and Glass (1949) on the pursuit of healing methods for pulpal exposures: historical perspectives.

Clinical observations and experimental studies in humans and laboratory animals have demonstrated that healing and repair of pulpal exposures by caries, trauma, or iatrogenic causes are possible with a variety of wound treatment methods. Yet clinical trials have shown that predictable long-term pulp tissue preservation may be an elusive goal and has led to doubts about pulp capping and pulpotomy as valid clinical procedures. Nevertheless substantial knowledge has accumulated over the years on the mechanisms and the treatment factors that are important to promote/support continued vital pulp functions. This article highlights some key contributions to our current knowledge base, which have come to light during the more than 50 years since a pioneering experimental study by Zander and Glass was published in the Triple O journal.

Aluminum Compounds↗
PubMed2000

Comparative radiopacity of tetracalcium phosphate and other root-end filling materials.

AIM: This study compared the radiopacity of tetracalcium phosphate (TTCP) and 11 root-end filling materials relative to human dentine. METHODOLOGY: Specimens of 2 mm thickness and a graduated aluminium stepwedge were placed on dental X-ray films and exposed to an X-ray beam. The optical densities of the specimens and aluminium steps were measured. The optical densities of the specimens were correlated to the equivalent thickness of aluminium with a regression analysis equation. The equation was used to calculate the equivalent aluminium thickness of each of the specimens. RESULTS: Nine of the materials were found to be of acceptable radiopacity (at least 2 mm Al more radiopaque than dentine). TCCP and two of the glass-ionomer compounds were found to have insufficient radiopacity to be radiographically distinguishable from human dentine. CONCLUSIONS: All the materials were found to be distinguishable radiographically from dentine, except for Vitrebond, TTCP and Ketac-Fil. Amalgam was the most radiopaque material and Ketac-Fil was the least radiopaque material tested.

Absorptiometry, Photon↗
PubMed2001

Mineral trioxide aggregate repair of lateral root perforations.

This study was conducted to observe the healing process of intentional lateral root perforation repaired with mineral trioxide aggregate (MTA). Forty-eight root canals of dogs' teeth were instrumented and filled. After partial removal of the filling, an intentional perforation was made with a bur in the lateral area of the root. The perforations were repaired with MTA or Sealapex (control group). Histological analysis occurred 30 and 180 days after treatment. Results showed no inflammation and deposition of cementum over MTA in the majority of the specimens. In the 180-day period, Sealapex exhibited chronic inflammation in all the specimens and slight deposition of cementum over the material in only three cases. In conclusion, MTA exhibited better results than the control group.

Aluminum Compounds↗
PubMed2006

Prostaglandin E production and viability of cells cultured in contact with freshly mixed endodontic materials.

AIM: To determine whether commonly used endodontic sealers could either induce or increase the release of prostaglandin E2 (PGE2) when in contact with cell types found in the periapical tissues. METHODOLOGY: Freshly mixed samples of Roth 801 sealer, Sealapex and ProRoot mineral trioxide aggregate (MTA) were placed in contact with cultured macrophages and fibroblasts for 24 h. The supernatant from the cultures was assayed for PGE2 using enzyme-linked immunosorbent assay. Cell viability counts were made. As a positive control, similar cultures were also exposed to lipopolysaccharide and the supernatant analysed for PGE2. Data were compared by anova. RESULTS: The three materials examined in these experiments did not stimulate increased PGE2 release from either of the cell lines. In control cultures, lipopolysaccharide increased PGE2 release from macrophages but not from fibroblasts. Viability counts revealed that, whilst Roth 801 sealer caused some cell death in both fibroblasts and macrophages, Sealapex led to cell death only in the macrophage cultures. ProRoot MTA did not lead to statistically significant cell death in either culture. CONCLUSIONS: Under 24-h culture conditions, the three freshly mixed test materials did not increase directly either production or release of PGE2 from either macrophages or gingival fibroblasts. Roth 801 decreased cell viability counts for both fibroblasts and macrophages. Sealapex decreases macrophage viability. ProRoot MTA did not affect viability in either cell line.

Aluminum Compounds↗
PubMed2005

Sealing effectiveness of materials used in furcation perforation in vitro.

OBJECTIVES: In this study the sealing ability of various materials used to repair furcation perforations was evaluated. DESIGN: Ninety human molars were endodontically treated and a perforation was made in the pulp chamber floor using a round bur. The teeth were inserted into a moistened flower sponge and perforation sites were sealed with one of the following materials: Mineral Trioxide Aggregate (ProRootM), Super-EBA, Vitremer, Hemarcol together with Super-EBA, Hemarcol together with Vitremer, Tricalcium phosphate together with AH26, Cavit W and amalgam. After eight months, the sealing effectiveness of the materials was evaluated in a double-blinded trial under a video-microscope by detecting the penetration of silver nitrate solution (50%w/w) in longitudinal tooth sections. RESULTS: Perforation sites filled with Hemarcol together with Vitremer or with MTA exhibited statistically less silver stain penetration while Cavit W or Tricalcium phosphate together with AH26 sealer failed to effectively seal the perforation sites. CONCLUSIONS: MTA alone or Vitremer in combination with a collagen sponge can be used effectively in the treatment of perforations in a furcation area.

Aluminum Compounds↗
PubMed2003

[Histological evaluation on repair of furcation perforation in dogs using mineral trioxide aggregate].

OBJECTIVE: To investigate histological response to immediate repair of different sizes of furcation perforation using MTA, Dycal and GIC. METHODS: Forty-two posterior teeth in three adult beagle dogs were randomly divided into two groups, small perforation group and large perforation group. Each group was then divided into three sub-groups which were repaired with MTA, Dycal and GIC respectively. The dogs were sacrificed 4 months later, and the specimens processed and examined under the light microscope. Inflammation, epithelial proliferation, and formation of hard tissue over the material were evaluated. RESULTS: In teeth repaired with MTA, five cases were free of inflammation, and the other nine cases were associated with slight or moderate inflammation. There was formation of cementum with cementoblast cells around it in four cases. In the group of Dycal, all specimens had moderate or severe inflammation. The deposition of irregular calcified tissues as well as a large quantity of inflamed cells were found in two cases of small perforation. Six cases presented epithelial proliferation. In the group of GIC, moderate or severe inflammation was seen in all cases except for one case of large perforation with fibrous tissues and sparse inflammatory cells around the material. Four cases presented epithelial proliferation. There was some relation between epithelial proliferation and size of perforation. CONCLUSION: MTA is superior to GIC and Dycal for immediate repairing furcation perforation in dogs owing to its less irritation to surrounding tissues and its ability to induce the formation of hard tissues.

Aluminum Compounds↗
PubMed2003

Interaction of inhalational anaesthetics with CO2 absorbents.

We review the currently available carbon dioxide absorbents: sodium hydroxide lime (=soda lime), barium hydroxide lime, potassium-hydroxide-free soda lime, calcium hydroxide lime and non-caustic lime. In general, all of these carbon dioxide absorbents are liable to react with inhalational anaesthetics. However, there is a decreasing reactivity of the different absorbents with inhalational anaesthetics: barium hydroxide lime >> soda lime > potassium-hydroxide-free soda lime > calcium hydroxide lime and non-caustic lime. Gaseous compounds generated by the reaction of the anaesthetics with desiccated absorbents are those that threaten patients. All measures are comprehensively described to--as far as possible--prevent any accidental drying out of the absorbent. Whether or not compound A, a gaseous compound formed by the reaction of sevoflurane with normally hydrated absorbents, is still a matter of concern is discussed. Even after very high loading with this compound, during long-lasting low-flow sevoflurane anaesthesias, no clinical or laboratory signs of renal impairment were observed in any of the surgical patients. Finally, guidelines for the judicious use of different absorbents are given.

Absorption↗
PubMedDate not supplied

Calcium modulators and the gut: an update.

Calcium is critical for stimulus-secretion coupling at the cellular level in the gut. Recent experimental evidence suggests a role for calcium modulating compounds in vivo. Specifically, calcium channel blocking drugs of the dihydropyridine class exert potent anti-secretory and anti-stress ulcer effects. However, these same compounds exacerbate ethanol-induced gastric mucosal injury. Calcium chelating compounds, including EDTA and EGTA, reduce both forms of experimental ulcer as well as gastric secretion. Mechanisms underlying the gastroprotective effects of calcium modulating agents include neural, hormonal, peptide and enzymatic activity and these compounds represent a viable avenue of research for future therapeutic development.

Animals↗
PubMed1976

Influence of the concentration of phosphorus, potassium, calcium and iron compounds on the microbial reduction of sulphates.

In the reduction process of sulphates by Desulfovibrio desulfuricans suitable concentration of mineral salts plays an important role. In particular, different K2HPO4, CaCl2 and Fe(NH4)2(SO4)2 content in the reaction medium has an observable effect on the reduction degree (x'), the induction time (t0) and the reduction rate constant (k). These data were recorded for 9 liquid media characterized by different content of mineral salts. The reaction rate constants were calculated for the reduction process in each medium. Optimal reduction conditions exists at the following element concentration ratios: P/S=0.068, K/S=0.086, Fe/S=0.08, N/S=0.33, C/S=1.80, Ca/S=0.03, Cl/S=0.80.

Calcium↗
PubMed1995

Growth control of human colon-adenocarcinoma-derived Caco-2 cells by vitamin-D compounds and extracellular calcium in vitro: relation to c-myc-oncogene and vitamin-D-receptor expression.

The human colon-cancer cell line Caco-2, though of malignant origin, is still able to express the c-myc proto-oncogene in a regulable fashion. Transition from the logarithmic growth phase into the quiescent, i.e., confluent state, is accompanied by a significant increase in the number of cells in the G0/G1 phase of the cell cycle and a concomitant reduction of c-myc mRNA and of nuclear association of c-myc protein. Conversely, growth stimulation by lowering extracellular [Ca++]0 to 0.25 mM results in up-regulation of c-myc expression levels and consequently inhibition of re-entry of Caco-2 cells into the G0/G1 phase. In contrast, regulation of c-myc in Caco-2 cells is completely resistant to vitamin-D sterols, since the anti-mitogenic action of I alpha, 25-dihdroxyvitamin D3 (I alpha, 25(OH)2D3) and of 2 synthetic analogs, I alpha, 25(OH)2-16-ene-23-yne-D3 and I alpha, 25(OH)2-26, 27-F6-16-ene-23-yne-D3, occurred independently of any change in c-myc mRNA and nuclear protein levels. Although the antiproliferative effect of the vitamin-D sterols requires high-affinity binding to the cytoplasmic vitamin-D receptor (VDR), vitamin-D sterols have no effect on VDR mRNA levels in Caco-2 cells. However, VDR mRNA expression changed in an antiparallel fashion to c-myc regulation upon transition between different growth states. This suggests that VDR mRNA abundance could nevertheless be important for vitamin-D-related c-myc-independent growth control in Caco-2 cells.

Antineoplastic Agents↗
PubMed1996

Acceptance of minerals and other compounds by calcium-deprived rats: 24-h tests.

We measured 24-h spontaneous intake of four to eight concentrations of 31 different solutions by groups of rats fed control or low-calcium diets. Relative to controls, those fed low-calcium diet had increased acceptance of one or more concentrations of sodium chloride, sodium acetate, and sodium bicarbonate, but not sodium gluconate. Differences in palatability between these sodium salts were unimportant because the rats fed low-calcium diet consumed more sodium chloride even if this was made less acceptable by adulteration with citric acid. The possibility that calcium-deprived rats have an enhanced general cation or mineral appetite was supported by findings of increased acceptance of one or more concentrations of nine of ten chloride minerals tested (aluminum chloride, ammonium chloride, ferric chloride, ferrous chloride, magnesium chloride, sodium chloride, potassium chloride, strontium chloride, zinc chloride). However, there were no differences in acceptance of any concentration of cesium chloride, magnesium sulfate, or lead acetate. Moreover, calcium-deprived rats drank more hydrochloric acid and malic acid than did controls. Thus the effect of calcium deficiency on intake was not confined to minerals. Acidity or bitterness did not appear important because there was no difference between the groups in intake of sulfuric acid, citric acid, or quinine hydrochloride. Consistent with the exacerbating effects of phosphates on calcium deprivation, deprived rats had decreased intakes of phosphates (sodium phosphate, potassium phosphate). However, they also had decreased intakes of sucrose and saccharin. It is clear that calcium deprivation does not induce a general increase in acceptance of all taste solutions, but there appears to be no simple explanation for what these animals consume.

Acids↗
PubMed2005

[Application of elemental microanalysis for estimation of osteoinduction and osteoconduction of hydroxyapatite bone implants].

Hydroxyapatite (HAp) ceramics based on calcium phosphates, chemical compounds being natural constructive element of bones is now regarded to be one of better implantation materials in osseous surgery and stomatology. HAp is poorly soluble and slowly resorbing in tissues material. Easiness of connecting of hydroxyapatite ceramics with other materials creates possibilities to produce new composites of chemical compounds containing calcium and easier resorbing. An important and till now not fully known problem is influence of hydrodroxyapatite grafts on the processes leading to production of calcium and phosphorus ions responsive for mineralization of bone tissue around the graft. Proliferation of osteoblasts and rate of osseous trabeculas production depends, among others, concentration of calcium and phosphorus ions. The main target of this study was the comparative analysis of the bone mineralisation rate after implantation of hydroxyapatite (HAp) and composites hydroxyapatite + beta tricalcium phosphate (HAp + TCP) and hydroxyapatite + calcium hydrosulfate (HAp + gypsum), on the basis of elemental microanalysis. Implantation studies were carried out on 24 rabbits. Sections were carried out 5, 9, 11 and 14 weeks after implantation of the tested materials. The carried out punctual analysis of the occurring elements and their topographic location (mapping) in bones after implantation showed essential differences among the tested grafts. Those differences were most significant after 5 and 14 weeks and depended on the rate of the tested materials resorption. On the basis of conducted macroscopic evaluation and scanning microscope assessment we can stated that the composite of HAp+TCP showed the best osteocunductive properties, while the best osteoinductive influence was shown by the composite HAp + gypsum.

Animals↗
PubMed1992

[Metabolic effects of phosphate receptors stimulating the ileal transport of calcium].

Several compounds, either metabolizable such as sorbitol and creatine or unmetabolizable such as L-xylose or ethyl-ethanolamine, increase ileal calcium transport, similarly to the well documented effect of lactose. These compounds increase the duration time but not the rate of calcium transport. They have no specific effect on intestinal calcium absorption but they prolong the presence of soluble calcium in the ileal loop, thus allowing the calcium absorption. This stimulating effect of these compounds on mineral absorption is associated with an increase of ileal mucosal ATP content.

Animals↗