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PubMed2004

Comparison of using calcium hydroxide or a dentine primer for reducing dentinal pain following crown preparation: a randomized clinical trial with an observation time up to 30 months.

The purpose of this study was to evaluate effect of a calcium hydroxide suspension [Ca(OH)2] or glutaraldehyde based dentine primer (GDP) to reduce tooth sensitivity after full crown preparation. Thirty-six patients were treated with Ca(OH)(2) on one tooth and with GDP on another. Patients completed a questionnaire regarding sensitivity during crown preparation, when the not-anaesthetized abutments were irritated [cotton pellet (20 degrees C)]. The teeth were tested before (T(0)) and after using the desensitizer (T(1)), again after 7 days (T(2)), 6 months (T(3)) and 30 months (T(4)). The results were registered on a visual analogue scale [0 (no pain)-100 (severe pain)]. The changes of tooth sensitivity between different testing times were analysed. The median and the (interquartile range) for the different time intervals for Ca(OH)(2) were DeltaT(0)-T(1): 5 (6-17), DeltaT(0)-T(2): 17 (14-32), and for GDP, DeltaT(0)-T(1): 9 (7-18) DeltaT(0)-T(2): 18 (16-33), the decreases in sensitivity were lower for DeltaT(0)-T(1) than for DeltaT(0)-T(2) for both desensitizers (P < 0.001). There was no statistical difference (P > 0.05) between the agents (DeltaT(0)-T(1), DeltaT(0)-T(2), DeltaT(3)-T(4)). Both substances might be useful in reducing tooth sensitivity after crown preparation, but no differences in the efficacy were found when comparing the materials.

Adult↗
PubMedDate not supplied

Treatment of molluscum contagiosum with potassium hydroxide: a clinical approach in 35 children.

Potassium hydroxide (KOH) is a strong alkali that has long been known to digest proteins, lipids, and most other epithelial debris of skin scrapings to identify fungal infections. To our knowledge, KOH has never been used for the treatment of molluscum contagiosum (MC). We evaluated 35 children with MC for the clinical effectiveness of treatment with topical 10% KOH aqueous solution. The solution was applied by the parents of affected children, twice daily, on each MC lesion. The therapy was continued until all lesions underwent inflammation and superficial ulceration. Thirty-two of 35 patients achieved complete clinical cure after a mean treatment period of 30 days. Three children discontinued treatment: two reported severe stinging of the lesions and refused further applications; the other, with giant MC lesions, developed a secondary infection with prolonged treatment. Therapy with KOH was found to be effective and safe in the treatment of MC in children.

Adolescent↗
PubMed2003

Calcium hydroxide reduces lipopolysaccharide-stimulated osteoclast formation.

OBJECTIVE: The purpose of this study was to determine the direct effects of lipopolysaccharide (LPS) on osteoclastogenesis and to assess the ability of calcium hydroxide-Ca(OH)(2)-to inhibit the osteoclast formation stimulated by LPS. STUDY DESIGN: RAW 264.7 cells were cultured with 50 ng/mL recombinant receptor activator of NF-kappaB ligand (RANKL) for 72 hours. RANKL was then removed, and the cells were treated with 0, 1, 10, or 100 ng/mL of LPS, Ca(OH)(2)-treated LPS, or 50 ng/mL of RANKL as a positive control for an additional 48 hours. Cells were fixed and stained with fluorescein isothiocyanate-conjugated phalloidin to detect actin ring formation, and histochemistry was performed to detect multinucleated cells expressing tartrate-resistant acid phosphatase activity. RESULTS: LPS induced osteoclast-like cell (OCL) formation in a dose-dependent manner when osteoclast precursor RAW 264.7 cells were pretreated for 72 hours with RANKL. Ca(OH)(2) significantly inhibited the ability of LPS to stimulate OCL formation. CONCLUSION: This study shows that LPS directly stimulates OCL formation. The detoxification of LPS by treatment with Ca(OH)(2) significantly reduced its ability to trigger the differentiation of OCLs.

Acid Phosphatase↗
PubMed1985

Stabilization of higher-valent states of iron porphyrin by hydroxide and methoxide ligands: electrochemical generation of iron(IV)-oxo porphyrins.

An electrochemical study of hydroxide- and methoxide-ligated iron(III) tetraphenylporphyrins possessing ortho-phenyl substituents that block mu-oxo dimer formation has been carried out. Ligation by these strongly basic oxyanions promotes the formation of iron(IV)-oxo porphyrins upon one-electron oxidation. Further one-electron oxidation of the latter provides the iron(IV)-oxo porphyrin pi-cation radical. These results are discussed in terms of chemical model studies and the enzymatic intermediate compounds I and II of the peroxidases.

Chlorides↗
PubMed1999

Hydroxide rather than histidine is coordinated to the heme in five-coordinate ferric Scapharca inaequivalvis hemoglobin.

The ferric form of the homodimeric Scapharca hemoglobin undergoes a pH-dependent spin transition of the heme iron. The transition can also be modulated by the presence of salt. From our earlier studies it was shown that three distinct species are populated in the pH range 6-9. At acidic pH, a low-spin six-coordinate structure predominates. At neutral and at alkaline pHs, in addition to a small population of a hexacoordinate high-spin species, a pentacoordinate species is significantly populated. Isotope difference spectra clearly show that the heme group in the latter species has a hydroxide ligand and thereby is not coordinated by the proximal histidine. The stretching frequency of the Fe-OH moiety is 578 cm-1 and shifts to 553 cm-1 in H218O, as would be expected for a Fe-OH unit. On the other hand, the ferrous form of the protein shows substantial stability over a wide pH range. These observations suggest that Scapharca hemoglobin has a unique heme structure that undergoes substantial redox-dependent rearrangements that stabilize the Fe-proximal histidine bond in the functional deoxy form of the protein but not in the ferric form.

Animals↗
PubMed1986

Rumen degradation and fractional outflow rates of nitrogen supplements given to cattle eating sodium hydroxide-treated straw.

1. Six rumen and abomasal cannulated heifers were used to study the effects of intake on the fractional outflow rates (FOR) of chromium-mordanted cotton-seed meal (Cr-CSM) and meat meal (Cr-MM), CrEDTA, ytterbium and lignin from the rumen. Values of FOR of Cr-CSM and Cr-MM were combined with values of nitrogen disappearance from the protein supplements, placed in porous synthetic (nylon) bags and incubated within the rumen (P), to calculate effective degradation (D) of CSM and MM when fed to heifers eating sodium hydroxide-treated straw. Also, N degradation in vivo (V) was measured as the difference between abomasal N flow and the sum of flows of microbial and endogenous N. 2. FOR were positively related to intake and differences between supplements were significant (P less than 0.01). FOR pertaining to high and low intakes respectively were 0.073 and 0.052 for Cr-CSM, 0.082 and 0.071 for Cr-MM, 0.030 and 0.023 for lignin, 0.082 and 0.073 for CrEDTA and 0.044 and 0.035 for Yb. 3. A rise of 28.8 and 13.4% in FOR of Cr-CSM and Cr-MM respectively, associated with an increase in intake from maintenance to 1.5 times maintenance, resulted in 10.7 and 2.2% reductions in D, 24 h after feeding, for CSM and MM respectively. 4. With the exception of CSM at the high intake, estimates of V were underestimated by D and were 8.6-25.0% greater than the D values when time of incubation (t) = infinity. The two techniques, however, ranked the degradation of the two supplements in the same order at both levels of intake. 5. Underestimation of V by D may be attributable to underestimation of P, overestimation of FOR (both resulting in underestimation of D) or overestimation of V due to biases associated with the estimation of this part of the comparison. The relative importance of these factors remains to be determined.

Animal Feed↗
PubMed1986

Supplemental protein degradation, bacterial protein synthesis and nitrogen retention in sheep eating sodium hydroxide-treated straw.

1. Alkali (sodium hydroxide)-treated wheat straw was given to six rumen- and abomasal-cannulated sheep to study the rumen degradation of cotton-seed meal (CSM) and barley (B), and the effects of these supplements on nitrogen retention and efficiency of bacterial protein synthesis were measured. 2. N degradation, using porous synthetic (nylon) bags incubated within the rumen (P), and in vivo measurement determined from the abomasal flow of N (V), distinguished quantitatively between the two supplements. Estimates of P, corrected for fractional outflow rates/h (FOR), underestimated estimates of V when FOR of undegraded protein from the rumen (k) of 0.05 and 0.08 were used. Estimates of V for CSM and B were 70.9 and 80.8% respectively. 3. Intakes of alkali-treated straw were not affected by the supplements. Intakes of digestible organic matter (DOM) for the diets comprising alkali-treated straw alone (W), straw plus CSM (WC) and straw plus barley (WB) were 477, 575 and 590 g/d respectively (P less than 0.05) and organic matter (OM) apparently digested in the rumen (OMADR) was 339, 399 and 435 g/d respectively (P less than 0.05). 4. On W, WC and WB respectively, flows at the abomasum were 11.0, 14.0 and 13.3 g/d for bacterial N (P less than 0.05) and 0, 2.8 and 0.5 g/d for dietary supplemental N; g bacterial N/kg OMADR were 32.4, 35.6 and 30.9 (P greater than 0.05) and N balances were 2.37, 4.27 and 3.29 g/d (P less than 0.05) on the respective treatments. It was suggested that supplements increased total OM intake as a result of increased OM digested in the rumen rather than OM flow from the rumen.

Animal Feed↗
PubMed1989

Comparison of potassium hydroxide digestion and a modified Kato technique for the semi-quantitative estimation of Schistosoma mansoni eggs in faeces.

A simple method for the semi-quantitative estimation of eggs of Schistosoma mansoni in stools, based on digestion of faeces in 4% potassium hydroxide (KOH), is described. The relative performance of KOH digestion and a modified Kato method showed that the former was more sensitive and that the KOH/Kato ratio for the geometric mean number of eggs per gram, in stools positive by both methods, was 3.51.

Feces↗
PubMedDate not supplied

Encapsulation of aluminium hydroxide fillers with poly-methyl-methacrylate.

A process was developed for the microencapsulation of inorganic filler particles with poly-methyl-methacrylate, to increase the interaction between the hydrophilic filler particles and a polymer matrix. The filler utilised was aluminium hydroxide with an average diameter of 1.9 microm and a specific surface area of 5 m2/g. The process comprised a surface modification, in which a monolayer of isopropoxy titanium isostearate was chemically bound to the surface to render it hydrophobic and to ensure a chemical bond between the filler and the organic phase. Then, an encapsulation reaction was carried out by means of an emulsion-like polymerization process at monomer starved conditions. The modified particles were stabilized in water with sodium-dodecyl-sulphate. A redox system consisting of cumene-hydroperoxide in combination with sodium-formaldehyde-sulphoxylate and iron(II) salt was applied for the initiation of the polymerization. Besides surface polymer, free polymer particles were also formed. The parameters which varied were the filler concentration, the concentration of the initiator components and the surfactant concentration. At optimum conditions, approximately 50% of the added monomer polymerized at the modified filler surface, thus forming encapsulated filler particles. SEM together with TGA analysis indicated that a smooth polymer layer had been formed on the filler surface. At high filler loading, however, coagulation occurred.

Aluminum Hydroxide↗
PubMed1992

Why aluminum phosphate is less toxic than aluminum hydroxide.

Initially characterized in uremic patients undergoing hemodialysis, toxic effects due to high aluminum (Al) body loads were subsequently observed in a number of conditions, in particular following ingestion of Al-containing antacids. Among compounds of this class, aluminum phosphate (AlPO4) was recognized as safer than aluminum hydroxide (Al(OH)3), which was thought to result from its lower solubility and thus absorption in the gastrointestinal (gi) tract. However, while virtually insoluble at acid pH, AlPO4 is more soluble than Al(OH)3 under alkaline conditions, leading to the hypothesis that Al is predominantly absorbed in the acidic region of the gi tract. Our present results suggest otherwise. Al bioavailability depends on the solubility of the salt ingested as well as on the physicochemical properties of the Al soluble complexes formed in the gi fluid. Anions of dietary acids may indeed dissolve significant fractions of Al salts and form absorbable Al complexes. It is in these terms that the well documented increase of Al gi absorption by citrate has been interpreted from computer-based speciation studies. Using similar calculations, we now demonstrate that a series of dietary acids (namely malic, oxalic, tartaric, succinic, aspartic and glutamic acids) can also dissolve significant amounts of Al(OH)3 and form Al neutral complexes available to the gi membrane. In contrast, both effects are far less apparent when Al is administered as AlPO4. We conclude from this observation that the lower toxicity of AlPO4 vs Al(OH)3 stems from its better capacity to resist dissolution and neutral complex formation in the presence of acids commonly present in food.

Aluminum↗
PubMed2002

The study of modified calcium hydroxides with surfactants for acid gas removal during incineration.

The primary objective of the present work is to use additives to extend the sulfation reaction of the calcium hydroxide (Ca(OH)2) used to control SO2 emission from incineration processes. There are two reasons for adding surfactants (surface-active agent): (1) to provide an appropriate dispersion of the Ca(OH)2', thus preventing particle agglomeration due to humidity; (2) to alter the sulfation reaction environment by adsorbing heterogeneous materials on the surface of the Ca(OH)2 to extend the adsorption equilibrium. A dry scrubber integrated with a fabric filter was employed to study the effect of surfactants on the removal efficiency of acid gas in the flue gas with Ca(OH)2 as the sorbent. The operating parameters evaluated include: (1) the different surfactants (calcium lignosulfonate, sodium lignosulfonate, alkyl naphthalene sodium sulfonate and beta-naphthalene sodium sulfonate condensates) and (2) the composition of acid gas (i.e. sulfur dioxide (SO2), nitrogen oxide (NO) and hydrogen chloride (HCl)). The results show that modified Ca(OH)2 with surfactants could effectively decrease the emission of acid gas during incineration. Different additives had individual absorption efficiencies on different acid gases. On the whole, sodium lignosulfonate and beta-naphthalene sodium sulfonate condensates had better sorption capacity for SO2 and NO, but not for HCl. In addition, when SO2 coexisted with NO and HCl, the concentration of NO and HCl will result in decrease or increase of the removal efficiency of SO2.

Air Movements↗
PubMed1998

Simultaneous sulfur dioxide and nitrogen dioxide removal by calcium hydroxide and calcium silicate solids.

At conditions typical of a bag filter exposed to a coal-fired flue gas that has been adiabatically cooled with water, calcium hydroxide and calcium silicate solids were exposed to a dilute, humidified gas stream of nitrogen dioxide (NO2) and sulfur dioxide (SO2) in a packed-bed reactor. A prior study found that NO2 reacted readily with surface water of alkaline and non-alkaline solids to produce nitrate, nitrite, and nitric oxide (NO). With SO2 present in the gas stream, NO2 also reacted with S(IV), a product of SO2 removal, on the exterior of an alkaline solid. The oxidation of S(IV) to S(VI) by oxygen reduced the availability of S(IV) and lowered removal of NO2. Subsequent acidification of the sorbent by the removal of NO2 and SO2 facilitated the production of NO. However, the conversion of nitrous acid to sulfur-nitrogen compounds reduced NO production and enhanced SO2 removal. A reactor model based on empirical and semi-empirical rate expressions predicted rates of SO2 removal, NO2 removal, and NO production by calcium silicate solids. Rate expressions from the reactor model were inserted into a second program, which predicted the removal of SO2 and NOx by a continuous process, such as the collection of alkaline solids in a baghouse. The continuous process model, depending upon inlet conditions, predicted 30-40% removal for NOx and 50-90% removal for SO2. These results are relevant to dry scrubbing technology for combined SO2 and NOx removal that first oxidizes NO to NO2 by the addition of methanol into the flue duct.

Air Pollutants, Occupational↗
PubMed2000

Production of activated carbons from pyrolysis of waste tires impregnated with potassium hydroxide.

Activated carbons were produced from waste tires using a chemical activation method. The carbon production process consisted of potassium hydroxide (KOH) impregnation followed by pyrolysis in N2 at 600-900 degrees C for 0-2 hr. The activation method can produce carbons with a surface area (SA) and total pore volume as high as 470 m2/g and 0.57 cm3/g, respectively. The influence of different parameters during chemical activation, such as pyrolysis temperature, holding time, and KOH/tire ratio, on the carbon yield and the surface characteristics was explored, and the optimum preparation conditions were recommended. The pore volume of the resulting carbons generally increases with the extent of carbon gasified by KOH and its derivatives, whereas the SA increases with degree of gasification to reach a maximum value, and then decreases upon further gasification.

Air Pollutants, Occupational↗
PubMed1979

A critique of the U.S. standard for industrial exposure to sodium hydroxide aerosols.

Published studies of the toxicity of sodium hydroxide aerosols are few. These studies were generally marred by inadequate characterization of particle size and chemical compositon and of the ambient humidity. Because NaOH aerosols can readily undergo reaction with carbon dioxide to form sodium carbonate, a much less alkaline (and less hygroscopic) compound, these shortcomings may warrant a reconsideration of the NaOH standard and the consideration of a Na2CO3 standard.

Aerosols↗
PubMed2001

The use of Mg/Al layered double hydroxide for color removal of textile wastewater.

Layered double hydroxide of Mg-Al-carbonate system (MACH) was prepared and its heat-treated product (MACHT) was obtained by calcination at 500 degrees C. The resulting materials were used as an adsorbent for removal of color from synthetic textile wastewater (STW) and textile wastewater (TWW). Batch kinetic study showed that these materials are an efficient adsorbent for textile dye. The maximum adsorption capacities between 16 to 32 mg of dyes per g of adsorbent was obtained by fitting the adsorption data to the Langmuir adsorption Isotherm. It was found that the adsorption capacity of MACHT is higher than MACH.

Adsorption↗
PubMed2001

Protective anti-Helicobacter immunity is induced with aluminum hydroxide or complete Freund's adjuvant by systemic immunization.

To determine whether systemic immunization against Helicobacter pylori could be achieved with an adjuvant approved for human use, the efficacy of vaccination with Helicobacter antigen in combination with aluminum hydroxide (AlOH) was evaluated in a murine model of Helicobacter infection. Immunization with antigen and AlOH induced interleukin-5-secreting, antigen-specific T cells, and immunization with antigen and complete Freund's adjuvant induced interferon-gamma-secreting, antigen-specific T cells, as determined by ELISPOT assay. Both immune responses conferred protection after challenge with either H. pylori or H. felis, as confirmed by the complete absence of any bacteria, as assessed by both histology and culture of gastric biopsy samples. Protection was antibody independent, as demonstrated with antibody-deficient muMT mice (immunoglobulin-gene knockout mice), and CD4(+) spleen T cells from immunized mice were sufficient to transfer protective immunity to otherwise immunodeficient rag1(-/-) recipients. These results suggest an alternative and potentially more expeditious strategy for development of a human-use H. pylori vaccine.

Adoptive Transfer↗
PubMedDate not supplied

A comparison of ethanolamine and potassium hydroxide as quantitative trapping agents for radiolabeled CO2 in metabolism studies.

The efficiency of ethanolamine and potassium hydroxide (KOH) as trapping agents for CO2 was determined using a flow of 500 mL/min through CO2 absorption towers containing trapping solutions. Radiolabeled 14CO2 was produced by acidification of suspensions containing Ba14CO3. Both 100% ethanolamine and 5M ethanolamine in 2-methoxyethanol were evaluated. With 200 mL of either solution, trapping efficiency of 14CO2 decreased when only 5% or less of the amount of ethanolamine available had reacted (22 mmoles of CO2 trapped). In contrast, use of 200 mL of 1M or 5M KOH was effective in retaining 88 mmoles of CO2. This is equivalent to the amount of CO2 produced by a rat over an 8-hr period. In summary, with flow rates commonly used in in vivo metabolism studies, the trapping efficiency of ethanolamine was far less than the theoretical efficiency. In these types of studies KOH would be a more suitable trapping agent or, if used, ethanolamine solutions must be changed frequently.

Carbon Dioxide↗
PubMed1985

Reduced cleavage by sodium hydroxide of methyladenine in DNA sequencing.

When the Maxam and Gilbert DNA sequencing method which is modified by Bencini et al. (Biotechniques Jan/Feb pp4-5, 1984) is applied to DNA containing methylated adenine in a GATC sequence, the cleavage reaction by sodium hydroxide is found to be greatly reduced in comparison to that of non-methylated adenine. Thus, a faint band in A greater than C reaction suggests a methyl adenine and can be used for its detection. That the faint band corresponds to a methyladenine was confirmed by Sanger sequencing of the same fragment and further by Maxam and Gilbert sequencing of the complementary strand of DNA, which was replicated in an E. coli strain either having or lacking methylation enzymes.

Adenine↗