SEARCH · Search PubMed

Results for “ALKALIES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMed1991

In vivo benzo[a]pyrene diol epoxide-induced alkali-labile sites are not apurinic sites.

We have used endonuclease IV from Escherichia coli as a probe for apurinic sites in the DNA of HeLa cells following treatment with an activated diol epoxide derivative of benzo[a]pyrene. DNA strand breaks and alkali-labile sites were observed that were repaired following exposure to the carcinogenic alkylating agent. The alkali-labile sites were not substrates for the apurinic site-specific endonuclease IV. We conclude that the alkali-labile sites formed in vivo by benzo[a]pyrene derivatives are not apurinic sites and probably arise as a consequence of rearrangement of the abundant N2-guanine adducts. This finding questions the involvement of apurinic sites in the mutagenic activity of benzo[a]pyrene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1989

Alkali-resistant protein phosphorylation and tyrosine kinase activity of epithelial cell types from normal and metaplastic canine prostates.

To determine how functional changes such as growth and differentiation in the prostatic epithelium would alter protein phosphorylation on tyrosyl residues, differentiated (secretory) and basal (non-secretory) prostatic epithelial cells from normal and from metaplastic canine prostates were labeled with [32P]phosphate and their alkali-resistant phosphoproteins were analyzed by autoradiography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The tyrosine protein kinase activity of the cells was also assayed by phosphorylation of a synthetic substrate, poly(Glu80-NaTyr20), in the presence of [gamma-32P]ATP. The prostates were characterized by tissue morphology and the cells by their density on Percoll gradients and [3H]thymidine incorporation into DNA. In prostates from intact dogs, tall columnar secretory epithelial cells were predominant and the non-secretory or basal epithelial cells were quiescent and did not incorporate [3H]thymidine. In metaplastic glands obtained from estrogen-treated castrated dogs, most of the isolated cells were non-secretory and synthesized DNA. Alkali-resistant phosphoproteins were present in all cell types. Except for two common phosphoproteins, p44 and p82, the relative phosphoprotein distribution within the gel differed when normal prostatic cells were compared to the metaplastic cells. However, the phosphoprotein patterns were the same in secretory and non-secretory cells from the same prostate tissue. On the other hand, the relative labeling intensity of phosphoproteins was always higher in non-secretory cells compared to corresponding secretory cells. Accordingly, tyrosine protein kinase (TPK) activity, expressed on a cell basis, was also higher in non-secretory cells; the ratios of TPK activities, non-secretory over corresponding secretory cells, was always higher than unity for all preparations but overlapped when cells from metaplastic glands were compared to those isolated from normal prostates. Thus, non-secretory epithelial cells isolated from either normal or metaplastic glands have a higher ability than corresponding secretory cells to phosphorylate endogenous alkali-resistant phosphoproteins and their TPK activity, measured with the synthetic substrate poly(Glu80-NaTyr20), is also higher.

Alkalies↗

PubMed2005

Direct NMR detection of the "invisible" alkali metal cations tightly bound to G-quadruplex structures.

We report the first direct solution NMR detection of the alkali metal cations (23Na+, 39K+, and 87Rb+) residing inside G-quadruplex channel structures formed by guanosine 5'-monophosphate and a DNA oligomer, d(TG4T). In solution, these channel alkali metal cations are tightly bound to the G-quadruplex structure and have been considered to be "invisible" to NMR spectroscopy for many years. Our finding that it is possible to directly observe these alkali metal cations by NMR spectroscopy provides a new tool for studying cation binding affinity and dynamics in G-quadruplex DNA.

Cations↗

PubMed2005

Comparative study of osteoconduction on micromachined and alkali-treated titanium alloy surfaces in vitro and in vivo.

This study sought to evaluate osteoconduction of Ti-6Al-4V surfaces under various conditions, including micro-patterned, alkali-treated, micro-patterned plus alkali-treated, and surfaces without any treatment as the control. The through-mask electrochemical micromachining (EMM) was used to fabricate micro-hole arrays on the titanium alloy surface. In vitro calcium phosphate formation on titanium surfaces was in static and dynamic simulated body fluid (SBF). In vivo comparison was conducted in the medullary cavity of dog femur using the implant cages which could provide the same physiological environment for specimens with different surface conditions. In vitro experiments indicate good conduction of calcium phosphate on the alkali-treated surfaces, and also better calcium phosphate deposition on the micro-hole surface than on the flat surfaces in dynamic SBF. In vivo experiments confirm the beneficial effect of alkaline treatment on osteoconduction. The results of in vivo experiments also indicate a synergistic effect of the alkaline treatment and the topographic pattern on osteoconduction.

Alkalies↗

PubMed2005

Antimicrobial potency of alkali ion substituted calcium phosphate cements.

Potassium and sodium containing nanoapatite cements were produced by the reaction of mechanically activated CaNaPO(4) (CSP), CaKPO(4) (CPP) and Ca(2)KNa(PO(4))(2) (CPCP) with a 2.5% Na(2)HPO(4) solution. The cements exhibited clinically acceptable setting times of approximately 5 min and compressive strengths of 5-10 MPa. The antimicrobial properties of the cements were tested with the agar diffusion test using Streptococcus salvarius, Staphylococcus epidermis and Candida albicans. All types of alkali ion containing cements showed a significantly higher antimicrobial potency with inhibition zones of approx. 4-11 mm than a commercial calcium hydroxide cement which resulted in small inhibition zones around the cement samples of a maximum of 1.5 mm. The antimicrobial properties of all the cements were not found to diminish even after longer incubation times. This behaviour was attributed to the formation of soluble alkaline metal phosphates during setting which increased the pH value in the agar gel around the alkali containing calcium phosphate cement to 8.5-10.7 compared to 6.5-8.0 for the Ca(OH)(2) product. The high antimicrobial potency of alkali-calcium phosphate cements may find an application in dentistry as pulp capping agents, root fillers or cavity liners.

Alkalies↗

PubMed2004

Cleavage reactions of the complex ions derived from self-complementary deoxydinucleotides and alkali-metal ions using positive ion electrospray ionization with tandem mass spectrometry.

The dissociation reactions of the adduct ions derived from the four self-complementary deoxydinucleotides, d(ApT), d(TpA), d(CpG), d(GpC), and alkali-metal ions were studied in detail by positive ion electrospray ionization multiple-stage mass spectrometry (ESI-MS(n)). For the [M + H](+) ions of the four deoxydinucleotides, elimination of 5'-terminus base or loss of both of 5'-terminus base and a deoxyribose were the major dissociation pathway. The ESI-MS(n) spectra showed that Li(+), Na(+), and Cs(+) bind to deoxydinucleotides mainly by substituting the H(+) of phosphate group, and these alkali-metal ions preferred to bind to pyrimidine bases rather than purine bases. For a given deoxydinucleotide, the dissociation pathway of [M + K](+) ions differed clearly from that of [M + Li](+), [M + Na](+), and [M + Cs](+) ions. Some interesting and characteristic cleavage reactions were observed in the product-ion spectra of [M + K](+) ions, including direct elimination of deoxyribose and HPO(3) from molecular ions. The fragmentation behavior of the [M + K](+) and [M + W](+) (W = Li, Na, Cs) adduct ions depend upon the sequence of bases, the interaction between alkali-metal ions and nucleobases, and the steric hindrance caused by bases.

Ions↗

PubMed2005

EPR and optical investigations of manganese ions in alkali lead tetraborate glasses.

Electron paramagnetic resonance (EPR) and optical absorption spectra of Mn2+ ions in different alkali lead tetraborate glasses 90R2B4O7+9.25PbO+0.75MnSO4 (R=Li, Na and K) and 90Li2B4O7+(10-x)PbO+xMnSO4 (x=0.1, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2 mol%) have been studied. The EPR spectrum of all the glass samples exhibit three resonance signals at g=2.0, 3.3 and 4.3. The resonance signal at g=2.0 is attributed to the Mn2+ ions in an environment close to an octahedral symmetry. The resonance signals at g=3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn2+ ions. The effect of temperature (123-433 K) and the composition dependence of EPR signals have been studied for Mn2+ ions in lithium lead tetraborate glasses. It is interesting to observe that the variation of paramagnetic susceptibility (chi) with temperature obeys Curie-Weiss law. From the slope of 1/chi versus T graph, the Curie constant (C) has been evaluated. The zero-field splitting (zfs) parameter D has been calculated for different alkali lead tetraborate glasses from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits three bands. An intense and broad band at lower energy side has been assigned to the spin-allowed (5Eg-->5T2g) transition of Mn3+ ions in an octahedral symmetry. The intense and sharp band and a broad band at higher energy side have been assigned to charge transfer bands. A red shift is observed with increase of alkali ion size. The optical band gap energy (Eopt) decreases, whereas the Urbach energies (DeltaE) increases with increase of Mn content. The theoretical values of optical basicity (Lambdath) of the glasses have also been evaluated.

Alkalies↗

PubMed2005

Therapeutic effect of topical administration of SN50, an inhibitor of nuclear factor-kappaB, in treatment of corneal alkali burns in mice.

We evaluated the therapeutic efficacy of topical administration of SN50, an inhibitor of nuclear factor-kappaB, in a corneal alkali burn model in mice. An alkali burn was produced with 1 N NaOH in the cornea of C57BL/6 mice under general anesthesia. SN50 (10 microg/microl) or vehicle was topically administered daily for up to 12 days. The eyes were processed for histological or immunohistochemical examination after bromodeoxyuridine labeling or for semi-quantification of cytokine mRNA. Topical SN50 suppressed nuclear factor-kappaB activation in local cells and reduced the incidence of epithelial defects/ulceration in healing corneas. Myofibroblast generation, macrophage invasion, activity of matrix metalloproteinases, basement membrane destruction, and expression of cytokines were all decreased in treated corneas compared with controls. To elucidate the role of tumor necrosis factor (TNF)-alpha in epithelial cell proliferation, we performed organ culture of mouse eyes with TNF-alpha, SN50, or an inhibitor of c-Jun N-terminal kinase (JNK) and examined cell proliferation in healing corneal epithelium in TNF-alpha-/- mice treated with SN50. An acceleration of epithelial cell proliferation by SN50 treatment was found to depend on TNF-alpha/JNK signaling. In conclusion, topical application of SN50 is effective in treating corneal alkali burns in mice.

Administration, Topical↗

PubMed1976

Effects of alkali cations on the nuclear magnetic resonance intensity of 23Na in rat liver homogenate.

Effects of alkali cations on the nuclear magnetic resonance intensity of 23Na were studied in rat liver homogenate. The loss in the resonance intensity of 23Na in the homogenate was able to be divided into two components, one of which is abolished by the addition of Cs+ ("Cs-sensitive component"), the other being insensitive to Cs+ ("Cs-insensitive component"). Both components were sensitive to guanidinium ion. In a pH range of 7.4-4.9, the Cs-sensitive component varied remarkably, but the Cs-insensitive component remained virtually unchanged. The sequence of effectiveness of alkali cations (300 mmol/kg sample) in restoring the fractional intensity of 23Na was: Cs approximately Na greater than Li approximately Rb greater than K. It was suggested that the sequences of effectiveness of alkali cations in abolishing the two components are quite different from each other. The present results were examined within the framework of a simple model. Within this framework, the results suggest that there occur, in particulate fractions, sites whose affinity for Cs+ is sufficiently lower than that for Na+.

Animals↗

PubMed1978

Strand breaks and alkali-labile bonds induced by ultraviolet light in DNA with 5-bromouracil in vivo.

Supercircular gamma phage DNA with 10 bromouracils/100 thymine bases, irradiated with 313 nm light in Tris buffer and sedimented on alkaline and neutral gradients, showed 4.6 alkali-labile bonds per true single-strand break, in agreement with Hewitt and Marburger (1975 Photochem. Photobiol. 21:413). The same DNA irradiated in Escherichia coli host cells showed about the same number of breaks in alkaline gradients for equal fluence, but only 0.5 alkali-labile bond per true break. Similarly, E. coli DNA with bromouracil irradiated in the cells showed only 10--20% more breaks when denatured with 0.1 M NaOH than under neutral conditions with 9 M sodium perchlorate at 50 degrees C. These results show that true single-strand breaks occur more frequently than alkali-labile bonds after ultraviolet irradiation of DNA containing bromouracil in cells.

Alkalies↗

PubMed2001

Ion chromatography on chelating stationary phases: separation of alkali metals.

Analytical 250x4.6 mm I.D. columns packed with iminodiacetic acid (IDA) derivatised silica were used to separate alkali metal ions and the ammonium ion in combination with non-suppressed conductivity detection. The addition of 2.5-10 mmol/l of the macrocyclic crown ether 18-crown-6 to the nitric acid eluent resulted in a change in the elution order and a significant improvement in the resolution between potassium and ammonium because of selective complexation of potassium. However, the admixture of 15-crown-5 did not improve the resolution of lithium and sodium, although 15-crown-5 is a selective complexing agent for sodium. Retention and resolution of lithium, sodium, ammonium, cesium, rubidium and potassium ions increased at lower temperatures down to 1 degree C. The simultaneous separation of alkali and transition metals under isocratic conditions was achieved with an eluent comprising 10 mmol/l 18-crown-6, 1.5 mmol/l dipicolinic acid, and 1.9 mmol/l nitric acid. The chromatographic system enabled the quantitation of alkali metal ions with detection limits in the low ppb range and excellent linearity. Finally, the applicability of the method was approved by quantitation of sodium, ammonium and potassium in different water samples.

Alkalies↗

PubMed2002

Hydroxyapatite formation on alkali-treated titanium with different content of Na+ in the surface layer.

Titanium can form a bone-like apatite layer on its surface in SBF when it is treated in NaOH. When pre-treated titanium is exposed to SBF, the alkali ions are released from the surface into the surrounding fluid. The Na+ ions increase the degree of supersaturation of the soaking solution with respect to apatite by increasing pH. On the other hand, the released Na+ cause an increase in external alkalinity that triggers an inflammatory response and leads to cell death. Therefore, it would be beneficial to decrease the release of Na+ into the surrounding tissue. The purpose of this study was to evaluate the hydroxyapatite formation on alkali-treated titanium with different content of Na+ in the surface layer. Using SEM, gravimetric analysis and measurement of calcium and phosphate concentration, it was found that the rate of apatite formation was not significantly influenced by a lower amount of Na+ in the surface layer. Titanium with the lowest content of Na+ could be more suitable for implantation in the human body. The amount of alkali ions released in the surrounding tissue is lower and the rate of apatite formation is identical to titanium with the highest content of Na+ in the surface layer.

Alkalies↗

PubMed2003

XPS study of bioactive graded layer in Ti-In-Nb-Ta alloy prepared by alkali and heat treatments.

Ti and Ti-based alloys have been widely used for the biomedical applications due to their superiorities of biocompatibility, mechanical properties and corrosion resistance. However, there has been the limiting factor for these metals to show the low affinity to the living bone. Most of commercially used Ti alloys have harmful alloying elements such as Al, V, etc. The purposes of this study are design of new Ti alloy having the good mechanical properties and corrosion resistivity without harmful alloying elements and to improve the bone-bonding ability between Ti-based alloy and living bone through the chemically activated process (alkali treatment) and thermally activated one (heat treatment). Mechanical properties of the Ti-In-Nb-Ta alloy were observed by tensile test (Instron model 8511). Corrosion potential and corrosion rate were investigated using a Potentiostate machine (EG&G, Princeton Applied Model 273, Boston, USA) with saline solution (9% NaCl) without dissolved oxygen at 37 degrees C. After alkali and heat treatments, the effects of the pre-treatments on the bonding property were evaluated by in vitro test. In this study, the surface changing behavior, which is apatite formation, of newly designed Ti-In-Nb-Ta alloy without harmful alloying elements was investigated through analyzing its surface by using X-ray photoelectron spectroscopy after surface activation treatments (alkali and heat treatments) and after subsequent soaking in the simulated body fluid.

Alkalies↗

PubMedDate not supplied

Effect of separate and combined maternal ingestion of alkali metals on the developing mouse.

The effect of postnatal maternal ingestion of LiCl, CsCl or both during weaning period on the developing newborn was studied in the albino mouse. Maternal exposure to CsCl alone or in combination with LiCl reduced the weanling body weight from corresponding control which persisted for a subsequent 2 weeks after separation of the offspring from maternal breast feeding. This was compared to a moderate reduction in offspring growth by maternal Li-exposure during alkali metal-free period. Exposure of nursing dams to either alkali metals studied, but not their combination, decreased brain weight of the developing mouse. The maternal Li-exposure caused a marked increase in female but not male offspring spleen weight as compared to a reduction of kidney weight from corresponding controls. Coadministration of CsCl with LiCl negated this sex-dependent Li-mediated changes of the offspring's tissue weights. The maternal Li-treatment caused sex-dependent induction of offspring hepatic aldehyde dehydrogenase but not alcohol dehydrogenase. The results suggest that breast feeding by nursing dams ingesting these alkali metals could cause retarded growth during development. The Cs+ appears to negate some of the changes produced by Li on brain and kidney weights. The interaction between Cs+ and Li+ may prove useful in minimizing some of the neonatal toxicity studied.

Animals↗

PubMed2000

Large-diameter lamellar keratoplasty in severe ocular alkali burns: A technique of stem cell transplantation.

PURPOSE: To evaluate the efficacy of large-diameter lamellar keratoplasty in cases of severe ocular alkali burns. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Nine eyes of nine patients with severe ocular alkali burns (grade III/IV) exhibiting corneal vascularization, conjunctivalization, and chronic inflammation were recruited from the Cornea Clinic of Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, a tertiary eye care center. INTERVENTION: Large-diameter lamellar keratoplasty was performed using McCarey-Kaufman media-preserved donor corneas. The patients were followed up for a minimum of 6 months. MAIN OUTCOME MEASURES: Symptomatic relief, time to epithelialization, best-corrected visual acuity, Schirmer I, tear film break-up time, and central corneal clarity were the parameters evaluated. RESULTS: The mean duration between the injury and surgery was 29.5 +/- 19.4 months. No intraoperative complications were seen. Successful epithelialization of the ocular surface was achieved in all but one eye, and the mean time to epithelialization was 5.2 +/- 4.9 days. One eye had a persistent epithelial defect which was managed with a bandage soft contact lens. All patients achieved symptomatic relief. The preoperative best-corrected visual acuity was </=1/60 in all the patients. There was a significant improvement in vision in six eyes postoperatively (P = 0.013). The corneal clarity was grade 2+ or better in five eyes and 1+ in four eyes. No recurrence of corneal vascularization or signs of rejection were seen in any eye during the mean follow-up of 7.4 +/- 3.2 months. Causes of no improvement of vision included the presence of subepithelial nebulomacular haze in one eye caused by persistent epithelial defect and residual stromal haze. CONCLUSIONS: Large-diameter lamellar keratoplasty is a useful therapeutic modality in cases of severe alkali burns. It is a single-stage procedure that provides a stable ocular surface because of stem cell supplementation and may visually rehabilitate the patient.

Adolescent↗

PubMed1980

Ascorbic acid in the treatment of alkali burns of the eye.

Severe ocular alkali burns in rabbits result in a decrease in aqueous humor ascorbate levels to one-third normal levels. If this deficiency is reversed by immediate treatment with parenteral or topical ascorbate, there is a significantly decreased incidence of subsequent corneal ulceration and perforation. The morphologic changes in these ulcerating corneas are typical of those noted in scorbutus (scurvy). It is concluded that alkali injury to the ciliary epithelial transport processes or ciliary body vasculature results in localized deficiency of ascorbic acid in the aqueous humor and cornea. The development of corneal ulceration is thought to be based on this deficiency which results in the failure of fibroblasts to produce sufficient collagen for repair. A randomized clinical trial of ascorbic acid in the treatment of human alkali burned eyes is now underway.

Alkalies↗

PubMed2000

Potentiation of the lethal effect of peroxygen on Bacillus cereus spores by alkali and enzyme wash.

Bacillus cereus present in pipes and heat-exchangers represents a potential quality problem for dairy industry. The peroxygen-containing disinfectants investigated had only negligible sporicidal effect when applied at the recommended in-use temperature and concentration. However, cleaning agents used before disinfection potentiated their lethal activity. Pre-exposure of B. cereus spores to 1% sodium hydroxide at temperatures over 40 degrees C increased the sporicidal effect of the peroxygen-containing disinfectant. The effect was dependent on the alkali concentration and the temperature. Also, a significant potentiating activity of an enzyme-based cleaning agent was obtained, but the effect was smaller than for alkali treatment. The results indicated that disinfectants based on peroxygen can be used to eliminate B. cereus spores at non-corrosive temperatures and concentrations if the surfaces are cleaned with alkali or enzyme-based disinfectants prior to disinfection.

Alkalies↗

PubMed1997

Analysis of wool fiber by alkali-catalyzed pyrolysis gas chromatography.

Alkali-catalyzed pyrolysis gas chromatography (PyGC) has been used to identify minute samples of wool fiber. The wool sample to which aqueous sodium hydroxide was added was pyrolyzed in a Curie-point pyrolyzer attached to a gas chromatograph or a gas chromatograph-mass spectrometer. The addition of an aqueous solution of sodium hydroxide increased the production of specific volatile pyrolysis products from the constitutive amino acid residues of wool protein, i.e. acetaldehyde from alanine or proline, isobutyronitrile from valine, 2-methylbutyronitrile from isoleucine, isovaleronitrile from leucine and toluene from phenylalanine. Compared with conventional non-catalyzed PyGC, the alkali-catalyzed PyGC was found to greatly improve the detection limit of wool fiber and make it possible to analyze very minute samples. The alkali-catalyzed PyGC presented here has been shown to be applicable to minute thermally-denatured samples of wool fiber which cannot be identified successfully by morphological inspection using a microscope or by using Fourier-transform infrared microspectroscopy. Furthermore, the present PyGC method was successfully used for several protein samples and was shown to be useful for analysis of proteins other than wool fibers by using different special pyrograms reflecting different amino acid compositions.

Alkalies↗