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PubMed1985

Volume regulation by Amphiuma red blood cells: strategies for identifying alkali metal/H+ transport.

The regulation of cell volume in response to anisotonic media, and in a broader perspective electroneutral alkali/metal H+ exchange transport, are currently areas of general interest to transport physiologists. In this paper I outline the basic features of volume-sensitive ion fluxes as studied with Amphiuma red blood cells. As has been shown in previous studies the alkali metal ion fluxes that are responsible for volume regulation by these cells are electroneutral by virtue of obligatory counter coupling with H+. The criteria for establishing the existence of electroneutral alkali metal/H+ exchange in these cells will be reviewed and expanded on. In the process, behavior and phenomena consistent with, as well as those unique to, electroneutral alkali metal/H+ exchange will be introduced, illustrated with experimental data, and discussed. Finally, based on thermodynamic considerations, kinetic behavior will be evaluated in terms of electroneutral alkali metal/H+ transport.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1982

Effects of alkali and oxygen on nitrosation in dimethylamine-nitrite mixtures with and without reductants.

Two types of 'alkali effect', i.e., the formation of NDMA by alkylization of nitrite-DMA mixtures with and without reductants, were investigated. In the reductant-free system, the 'alkali effect' was found to increase with decreasing pH of the initial system. 'Cofactors' (some buffering agents or metallic ions) were essential for the 'alkali effect' in the presence of ascorbate, but were not necessary when tannic acid was the reductant. It may be concluded that free NO is released from nitrite by the action of reductants, with or without 'cofactors', and that N2O3 and/or N2O4, the nitrosating agents, are derived from NO via NO2 by air oxidation. Dinitrogen trioxide, generated from HNO2 in an acidic solution, and N2O4, derived from N2O3, are considered to be the main nitrosating agents producing the 'alkali effect' in the reductant-free system, but the presence of O2 also showed a remarkable enhancing effect on NDMA formation in this system.

Alkalies↗
PubMed1981

[Influence of soap and Syndet upon alkali resistance (author's transl)].

The alkali resistance test data of 189 metal workers (66 female, 123 male) and 28 college students (12 female, 16 male) was analysed by means of correlation analysis and "Vorzeichentest" relative to the dependence on age group and sex as well as the difference of the right- and left- arm-alkali resistance. The results showed no significant differences. The right-left comparison of a soap and synthetic detergent-washing of the forearms of 14 college students (7 female, 7 male) and 11 metal workers (2 female, 9 male), repeated after 4 and 8 weeks respectively, which was carried out in the following without age and sex differentiation, showed that the synthetic detergent washing had less influence on the alkali resistance than the soap washing. The interpretation of alkali resistance testing should be based upon knowledge about time and modus of previous washing and occupational exposure.

Aging↗
PubMed2002

Croconic acid and alkali metal croconate salts: some new insights into an old story.

The solid-state structures of a series of alkali metal salts of the croconate dianion (C(5)O(5)(2-)) and of croconic acid (H(2)C(5)O(5)) have been determined. The alkali metal croconates were obtained by ring contraction of rhodizonic acid (H(2)C(6)O(6)), upon treatment with alkali metal hydroxides and recrystallisation from water. The novel species Na(2)C(5)O(5) x 2H(2)O, Rb(2)C(5)O(5) and Cs(2)C(5)O(5), as well as the mixed hydrogencroconate/croconate salt K(3)(HC(5)O(5))(C(5)O(5)) small middle dot2 H(2)O are described and compared with the Li(+), K(+) and NH(4)(+) salts. Single crystals of croconic acid were obtained by crystallisation of croconic acid in the presence of HCl. Crystal structure determinations showed that the C(5)O(5)(2-) ions tend to organize themselves in columns. The interplanar separations lie in the narrow range 3.12-3.42 A and do not necessarily reflect the presence of pi-stacking interactions. It is argued that the small interplanar separation is the result of a compromise between packing of flat croconate units and the spherical cations together with the water molecules that fill the coordination spheres of the alkali metal atoms.

Journal Article↗
PubMed2002

Alkali and alkaline-earth-metalated forms of calix[4]arenes: synthons in the synthesis of transition metal complexes.

This is the first coherent report on the metalation of calix[4]arene by alkali and alkaline-earth metals, thus providing a high-yield production of appropriate synthons for the synthesis of transition metal calix[4]arenes. In addition, various facets of the coordination chemistry by calix[4]arene anions of alkali and alkaline-earth metal ions have been singled out. Among them: 1) the exo and endo coordination of metal ions by the calix[4]arene skeleton; 2) the pi solvation of the ions by the phenyl rings; 3) the ion-carrier properties of metallacalix[4]arenes; 4) the simulation of the kinetically labile coordination sphere of alkali and alkaline-earth metal ions by a polyoxo rigid skeleton. The peculiarities of the complexation of alkali and alkaline-earth metal ions by calix[4]arenes outlined are deduced from the synthesis and the structural characterization both in solution ((1)H NMR) and in the solid state (X-ray structure analysis) of the following classes of compounds: 1) [p-tBu-calix[4](OMS(n))(4)](2) (M=Li, Na, K); 2) [p-tBu-calix[4](OR)(2)(O)(2)ML] (M=Mg, L=THF, R=C(5)H(9); M=Ca, L=TMEDA (tetramethylethylenediamine), R=C(5)H(9); M=Ca, L=DME (dimethoxyethane), R=C(5)H(9); M=Ba, L=TMEDA, R=C(5)H(9); M=Ba, L=none, R=C(5)H(9)); 3) [p-tBu-calix[4](OC(5)H(9))(2)(O)(2)Ca(2)I(2)(MeCN)(2)]; 4) [(p-tBu-calix[4](OR)(2)(O)(2))(2)BaNa(2)].

Journal Article↗
PubMed2005

Crystal structures and topological aspects of the high-temperature phases and decomposition products of the alkali-metal oxalates M2[C2O4] (M=K, Rb, Cs).

The high-temperature phases of the alkali-metal oxalates M2[C2O4] (M = K, Rb, Cs), and their decomposition products M2[CO3] (M = K, Rb, Cs), were investigated by fast, angle-dispersive X-ray powder diffraction with an image-plate detector, and also by simultaneous differential thermal analysis (DTA)/thermogravimetric analysis (TGA)/mass spectrometry (MS) and differential scanning calorimetry (DSC) techniques. The following phases, in order of decreasing temperature, were observed and crystallographically characterized (an asterisk denotes a previously unknown modification): *alpha-K2[C2O4], *alpha-Rb2[C2O4], *alpha-Cs2[C2O4], alpha-K2[CO3], *alpha-Rb2[CO3], and *alpha-Cs2[CO3] in space group P6(3)/mmc; *beta-Rb2[C2O4], *beta-Cs2[C2O4], *beta-Rb2[CO3], and *beta-Cs2[CO3] in Pnma; gamma-Rb2[C2O4], gamma-Cs[C2O4], gamma-Rb2[CO3], and gamma-Cs2[CO3] in P2(1)/c; and delta-K2[C2O4] and delta-Rb2[C2O4] in Pbam. With respect to the centers of gravity of the oxalate and carbonate anions, respectively, the crystal structures of all known alkali-metal oxalates and carbonates belong to the AlB2 family, and adopt either the AlB2 or the Ni2In arrangement depending on the size of the cation and the temperature. Despite the different sizes and constitutions of the carbonate and oxalate anions, the high-temperature phases of the alkali-metal carbonates M2[CO3] (M = K, Rb, Cs), exhibit the same sequence of basic structures as the corresponding alkali-metal oxalates. The topological aspects and order-disorder phenomena at elevated temperature are discussed.

Carbonates↗
PubMed2003

Biology of alkali- and heat-treated titanium implants.

In cementless fixation systems, surface character is an important factor. Alkali and heat treatments of titanium metal have been shown to produce strong bonding to bone and a higher ongrowth rate. In this study we examined the effect of alkali and heat treatments on titanium rods in an intramedullary rabbit femur model, in regard to the cementless hip stem. The implant rods were 5 mm in diameter and 25 mm in length. Half of the implants were immersed in 5 mol/L sodium hydroxide solution and heated at 600 degrees C for 1 h (AH implants), and the other half were untreated (CL implants). The rods were implanted into the distal femur of the rabbits; AH implants into the left femur and CL implants into the right. The bone-implant interfaces were evaluated at 3, 6, and 12 weeks after implantation. Pull-out tests showed that the AH implants had a significantly higher bonding strength to bone than the CL implants at each time point. As postoperative time elapsed, histological examination revealed that new bone formed on the surface of both types of implants, but significantly more bone made direct contact with the surface of the AH implants. At 12 weeks, approximately 56% of the whole surface of the AH implants was covered with the bone. In conclusion, alkali- and heat-treated titanium offers strong bone bonding and a high affinity to bone as opposed to a conventional mechanical interlocking mechanism. Alkali and heat treatments of titanium may be suitable surface treatments for cementless joint replacement implants.

Animals↗
PubMed2000

The Influence of Alkali Metal Ions on Homogeneous Nucleation of Al(OH)(3) Crystals from Supersaturated Caustic Aluminate Solutions.

Homogeneous nucleation of Al(OH)(3) crystals from synthetic, optically clear, caustic aluminate solutions and the influence of alkali metal ion (Na(+) versus K(+)) have been investigated under isothermal, batch crystallization conditions. The nucleation kinetics showed a seventh-order dependence upon Al(III) relative supersaturation and a strong temperature effect. Activation energy of 160 kJ mol(-1) and interfacial energy of 33 mJ m(-2) were estimated and found to be independent of alkali ion, as was the Al(OH)(3) equilibrium solubility. The nucleation rate, however, was faster in aging sodium than in potassium aluminate solutions. It appears that Na(+) ions provide greater stability for the formation and densification of Al(III)-containing, supramolecular clusters which grow more rapidly into Al(OH)(3) crystallites than do K(+) ions. The development of the Al-OH octahedral structure of Al(OH)(3) nuclei is an alkali metal ion-mediated, chemical reaction-controlled condensation process, displaying specific gibbsite (gamma-Al(OH)(3))-bayerite (alpha-Al(OH)(3)) dimorphism. Furthermore, significant differences in the level of alkali ion incorporation, reflecting in the purity and morphology of the crystalline product, were observed. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Effects of Flow Rate and Alkali-to-Acid Ratio on the Displacement of Acidic Oil by Alkaline Solutions in Radial Porous Media.

Alkaline flooding is a method of enhanced oil recovery that relies on the formation of surface-active substances in situ by a chemical reaction between acidic components in the oil and an alkaline reagent. As the injected alkali advances through the porous medium, it keeps contacting fresh oil. At some moment dependent on the alkali/acid concentrations and the velocity, the alkali at the advancing front may become depleted and the flood becomes interfacially nonreactive. The present study is aimed at investigating the above-mentioned phenomena. Displacement studies were conducted in radial cells containing sintered glass beads as a porous medium. Light paraffin oil acidified with 10 mmol/L of linoleic acid served as the displaced (oil) phase while the displacing aqueous solution contained 0-25 mmol/L of sodium hydroxide. The highest oil recovery was obtained under the conditions of low flow rate and high alkali concentration. Increasing the flow rate at high NaOH concentration resulted in decreasing oil recovery up to a certain threshold flow rate. Conversely, the amount of oil recovered by waterflooding only (no alkali) initially increased with increasing flow rate up to the same threshold flow rate beyond which there was no difference between the alkaline flood and a waterflood. Copyright 2000 Academic Press.

Journal Article↗
PubMed2003

Speciation of phytate ion in aqueous solution. Alkali metal complex formation in different ionic media.

The acid-base properties of phytic acid [ myo-inositol 1,2,3,4,5,6-hexakis(dihydrogen phosphate)] (H(12)Phy; Phy(12-)=phytate anion) were studied in aqueous solution by potentiometric measurements ([H+]-glass electrode) in lithium and potassium chloride aqueous media at different ionic strengths (0< I mol L(-1)< or =3) and at t=25 degrees C. The protonation of phytate proved strongly dependent on both ionic medium and ionic strength. The protonation constants obtained in alkali metal chlorides are considerably lower than the corresponding ones obtained in a previous paper in tetraethylammonium iodide (Et(4)NI; e.g., at I=0.5 mol L(-1), log K(3)(H)=11.7, 8.0, 9.1, and 9.1 in Et(4)NI, LiCl, NaCl and KCl, respectively; the protonation constants in Et(4)NI and NaCl were already reported), owing to the strong interactions occurring between the phytate and alkaline cations present in the background salt. We explained this in terms of complex formation between phytate and alkali metal ions. Experimental evidence allows us to consider the formation of 13 mixed proton-metal-ligand complexes, M(j)H(i)Phy((12-i-j)-), (M+ =Li+, Na+, K+), with j< or =7 and i< or =6, in the range 2.5< or =pH< or =10 (some measurements, at low ionic strength, were extended to pH=11). In particular, all the species formed are negatively charged: i+j-12=-5, -6. Very high formation percentages of M+-phytate species are observed in all the pH ranges investigated. The stability of alkali metal complexes follows the trend Li+ > or =Na+K+. Some measurements were also performed at constant ionic strength (I=0.5 mol L(-1)), using different mixtures of Et(4)NI and alkali metal chlorides, in order to confirm the formation of hypothesized and calculated metal-proton-ligand complex species and to obtain conditional protonation constants in these multi-component ionic media.

Journal Article↗
PubMed2002

Analysis of immediate changes of water-soluble metabolites in alkali-burned rabbit cornea, aqueous humor and lens by high-resolution 1H-NMR spectroscopy.

PURPOSE: To investigate immediate changes in water-soluble metabolites of ocular tissue in alkali-burned eyes by using high-resolution 1H-NMR spectroscopy. METHODS: Adult New Zealand rabbit eyes were burned with 1 M NaOH for 1 min. Normal eyes were used as control. Samples from aqueous humor and perchloric acid extracts of the cornea and lens were analyzed on a NMR spectrometer operating at 500 MHz for protons. Metabolites were quantified by comparing peak area with an added internal standard, TSP (3'-trimethylsilylpropinate-2,2,3,3-d4). RESULTS: Alkali burn of corneal surface causes immediate changes in concentration of many water-soluble metabolites in the anterior segment. Even as far away as the lens a significant increase in lactate was found. Cornea showed a significant increase in glucose and a significant decrease in hypo-taurine concentration. Most changes were observed in aqueous humor, with significant increases in succinate, creatine, scyllo- and myo-inositol and a significant decrease in citrate concentration. Furthermore, a small decrease in ascorbate concentration in aqueous humor was observed. CONCLUSIONS: The present study provides a valuable contribution to the knowledge of metabolic alterations in alkali-burned eyes. It shows that 1H-NMR spectroscopy is well suited for simultaneous qualitative and quantitative analysis of changes of metabolite concentrations in damaged tissues. This can help us to better evaluate and understand the biological alterations due to alkali burn.

Amino Acids↗
PubMed1998

Changes in mineral composition of rabbit corneas after alkali burn.

BACKGROUND: Mineral balance is essential for maintaining corneal transparency. In preliminary investigations, we found alterations of mineral concentrations in the human cornea after chemical burns. In this prospective study the mineral content of the rabbit cornea was quantified after experimental alkali burns. METHODS: Thirty-two eyes of rabbits were burnt for 30 s with 1 M NaOH. A short period of saline rinsing followed, but no further therapy was given. The eyes of 20 healthy rabbits served as a control. We measured the water content by weighing the cornea before and after drying. The mineral content of the cornea was determined in different stromal layers using energy-dispersive X-ray analysis in the scanning electron microscope. Groups of eight rabbits were examined on days 0, 1, 4 and 8 after the experimental burns. RESULTS: After alkali burns the mineral composition of the corneal stroma changed considerably. Sodium was present in high concentrations immediately after burning, up to 708 mmol/kg dry weight, and returned to normal on day eight. Chlorine increased significantly throughout the whole period. Sulphur concentrations stayed almost normal, showing only a minute loss of ground substance after alkali burn. A considerable and increasing edema could be concluded from the water content. CONCLUSIONS: Alkali burns resulted in a dramatic change of the corneal mineral content. Therapeutic intervention with appropriate solutions is required to restore and maintain the normal mineral composition of the denuded corneal stroma.

Animals↗
PubMed1998

Immunolocalization of proto-oncogene products in keratocytes after epithelial ablation, alkali burn and penetrating injury of the cornea in rats.

BACKGROUND: We examined the immunolocalization of proto-oncogene products, including c-Fos and c-Jun, in the rat cornea during epithelial and stromal wound healing after simple epithelial ablation, penetrating injury or alkali burn. METHODS: Eighty-four male Wistar rats were divided into three groups and subjected to treatments as follows: (a) ablation of central corneal epithelium leaving basement membrane intact, (b) alkali burn in the central cornea with 1 N NaOH and (c) penetrating injury at the central cornea. The affected eyes were then enucleated after various intervals of healing. The frozen sections were immunohistochemically stained with the antibodies against proto-oncogene products. RESULTS: c-Fos- and c-Jun-immunoreactive cells were detected in the epithelium around the epithelial defect from 60 to 120 min after these treatments. The distribution of these cells were varied in these three types of injury. The immunoreactivities for these proteins were also detected in keratocytes after epithelial ablation. In the corneas with alkali burn, the immunoreactivities were detected in the keratocytes in the whole corneal stroma, and these immunoreactions were stronger than those observed in simple epithelial ablation. In the corneas with penetrating injury, such immunoreaction was seen only in keratocytes around the wound. CONCLUSION: These findings indicate that activator protein 1-mediated transcriptional activation for epithelial migration is initiated in the early phase after each injury, and that stromal keratocytes are also transcriptionally activated not only by alkali burn or penetrating injury but also by simple epithelial ablation in which basement membrane was not affected.

Animals↗
PubMed1994

Alkali-soluble and insoluble fluoride in erupted and unerupted human enamel from a high fluoride area with a low fluorosis score.

The amounts of fluoroapatite and 'CaF2-like' fluoride (F) were determined in enamel of unerupted and erupted teeth that had been exposed in vivo to 1.8-2.6 parts/10(6) F in the drinking water and to brushing with F dentifrice at least once a day, and occasionally to a F mouth-rinse (0.022% F). Enamel was sampled by acid-etching and the F levels were measured with an adapted F ion-selective electrode. More F was built into the deeper enamel in the high-F area than in a similar low-F area. Unerupted enamel did not etch significantly (p > 0.05) deeper than erupted enamel. No significant differences (p > 0.05) were found in the F concentrations amongst the following: alkali-washed erupted, unwashed erupted, alkali-washed unerupted and unwashed unerupted at the outer most enamel (approx. 6 microns). However the erupted enamel (alkali-washed or not) showed higher F levels than unerupted enamel (alkali-washed or not) between approx. 6 microns and greater than 100 microns. The increase of F for this high-F area was about 100% in the deeper enamel while for a low-F area it was approx. 78% in the most outer enamel with no increase after a depth of about 20 microns. In contrast to a similar low-F area (water F < 0.10 parts/10(6)), no significant 'CaF2-like' F could be detected in erupted or unerupted enamel for the high-F area.

Dental Enamel↗
PubMed1988

Age-dependent accumulation of alkali-labile sites in DNA of post-mitotic but not in that of mitotic rat liver cells.

The amount of spontaneous damage in the DNA of rat liver cells was measured by using the alkaline elution assay. An age-related increase of approximately 700 detectable alkali-labile sites (80%) was found for rat parenchymal liver cells; cells from 6-month-old rats contained approximately 900 alkali-labile sites per cell while cells from 36-month-old rats contained approximately 1600 alkali-labile sites. In contrast to the situation with the postmitotic parenchymal liver cells, no age-related increase in the number of alkali-labile sites was found for the non-parenchymal liver cell fraction, which has a higher mitotic activity. These results support the hypothesis that aging takes place predominantly in postmitotic cells.

Aging↗
PubMed2005

Comparative study of alkali- and acidic organic solvent-soluble hemicellulosic polysaccharides from sugarcane bagasse.

Two-stage treatments of sugarcane bagasse with mild alkali and acidic 1,4-dioxane were performed. Pretreatment with 1M NaOH aqueous solution at 20, 25, 30, 35, and 40 degrees C for 18 h released 55.5%, 57.3%, 59.1%, 60.9%, and 62.1% of the original hemicelluloses, respectively. Post-treatment of the corresponding alkali-treated residue with 1,4-dioxane-2M HCl (9:1, v/v) at 87 degrees C for 2h, respectively, degraded 11.6%, 11.9%, 11.4%, 10.9%, and 10.6% of hemicelluloses (% dry starting material). It was found that the five alkali-soluble hemicellulosic preparations contained a much higher amounts of xylose (78.0-82.2%) and slightly higher uronic acids (4.8-5.8%), mainly 4-O-methyl-alpha-d-glucopyranosyluronic acid, but were lower in arabinose (9.3-11.7%) and glucose (2.2-4.1%) than those of the corresponding five acidic dioxane-degraded hemicellulosic fractions in which xylose (44.9-46.8%), arabinose (35.9-38.1%), and glucose (13.0-13.7%) were the major sugar constituents. The studies revealed that the five alkali-soluble hemicellulosic preparations were more linear and acidic, and had a large molecular weight (35,200-37,430 g mol(-1)) than those of the hemicellulosic fractions (12,080-13,320 g mol(-1)) degraded during the acidic dioxane post-treatment. This demonstrated that the post-treatment with acidic dioxane under the condition used resulted in substantial degradation of the hemicellulosic polymers. The 10 hemicellulosic samples were further characterized by FT-IR and 1H and 13C NMR spectroscopy, GPC and thermal analysis, and the results are reported.

Cellulose↗
PubMed2004

Changes of uPA and uPA-R expression in the cornea after alkali burn.

PURPOSE: To investigate the expression levels of uPA and uPA-R in corneal repair after alkali burn. METHODS: The corneal alkali burn models were established in vitro and in vivo, then immunocytochemistry (ICC) of uPA/uPA-R and image analysis and statistical evaluation were performed to determine their expression levels both in vitro and in vivo. RESULTS: Compared with control group, the expressions of uPA and uPA-R after alkali burn had no significant increases till 6h, then increased rapidly from 12h to 24h and reached their maxima at 24h. From 24h, their expression levels decreased rapidly. In vivo, they rebounded again after 48h and attained their second peaks at 96h, respectively. After that, their expressions decreased again. The uPA-positive reaction mainly distributed in the cytoplasm while that of uPA-R mostly distributed on the cellular membrane. Their expression changes were similar to each other, both in vivo and in vitro. In vivo, uPA and uPA-R expressed and gathered in the basal layer of corneal epithelium. CONCLUSIONS: These results suggest that the time phase of 24h after wound is the typical stage associating with the expressional maximum of uPA and uPA-R both in vivo and in vitro. Furthermore, the results also imply that the expression changes of uPA and uPA-R correlate to the wound healing after the corneal alkali burn, uPA and uPA-R coordinate with each other to stimulate the wound healing.

Animals↗
PubMed2005

The effects of acid and alkali modification on the adsorption performance of fuller's earth for basic dye.

The objective of this work was to prepare modified adsorbents from fuller's earth (FE) by acid and alkali treatment for enhancement cationic dye adsorption. Toluidine blue (TB) was selected as adsorbate for evaluating the adsorption performance of fuller's earth samples, which was affected significantly by acid and alkali modification. The adsorption of TB was studied by visible spectra. The absorption band of the monomer at low loading of TB in FE suspension with respect to its maximum in aqueous solution is red-shifted, which is related to accessibility of dye interlamellar space in the presence of positively charged surface sites. Since all surfaces are negatively charged under experimental conditions, this effect has not been observed in acid- and alkali-treated FE suspensions. It was seen that the adsorption capacity of alkali-treated surface (FEAl) for TB was higher than these of acid-treated adsorbent (FEAc) and FE. Scanning electron micrographs (SEM) and X-ray diffraction (XRD) and fluorescence (XRF) spectra were applied to analyze the structure of the raw and modified FE samples. Absence of any identifiable amount of a crystalline compound in the solid reaction products after acid treatment was confirmed by XRD and SEM, whereas the crystalline form of FEAl was preserved. Experimental data for high-concentration regions were well described by Freundlich and Langmuir adsorption equations. The thermodynamic parameters were estimated for FE, FEAc, and FEAl by using temperature dependence of adsorption equilibrium constants.

Journal Article↗