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 469 records · Page 26Linked to original sources

PubMed1984

Mechanisms of recovery from sublethal damage and potentially lethal damage induced by BrdUrd/313 nm light treatment: alkali-labile lesions.

BrdUrd pulse labelling of synchronous Chinese hamster cell cultures was used to correlate repair of sublethal damage with removal of alkali-labile lesions. Both processes were modified in a quantitatively similar manner by cysteamine. In addition, the age responses for repair of sublethal damage and for cysteamine reduction of repair agreed. Through the use of thymidine as an S-phase-blocking agent it was further demonstrated that progression past the S-phase of the cell cycle was required for the loss of resistance to UVB light in BrdUrd-substituted cells. Similarly, a thymidine block administered before synthesis upon the BrdUrd-substituted template prevented the cell from acquiring the sensitivity to UVB light normally associated with synthesis on a lesioned template. The UVB-light-sensitive mutant V79-UC was shown to have reduced capacities both for the accumulation of sublethal injury and for the removal of alkali-labile lesions. These data support the notion that alkali-labile lesions are responsible for sublethal damage in BrdUrd pulse-labelled Chinese hamster cells.

Animals↗

PubMed1980

Chemical characterization of an alkali-labile bond in the polypeptide of proline reductase from Clostridium sticklandii.

In previous studies, it was shown that a 4600-dalton pyruvate-containing peptide is released from proline reductase by mild alkali treatment. The alkali-sensitive bond proved to be between Ser-Glu, and it was suggested that an ester, rather than a peptide linkage, might be involved. In the present study, the effects of additional esterolytic reagents, (I) LiBH4 and (II) NH2OH, on proline reductase have been investigated and compared with 0.1 N NaOH-induced cleavage. Treatment with reagents I and II released a peptide identical with the peptide released by alkali as judged by electrophoretic mobility on thin layer sheets, COOH-terminal analyses, and amino acid compositional studies. The glutamic acid residue is converted to alpha-amino-delta-hydroxyvaleric acid after reductive cleavage with LiBH4. The liberation of the peptide fragment by the relatively specific esterolytic reagent, LiBH4, provides additional support of the presence of an ester linkage in native proline reductase.

Amino Acid Oxidoreductases↗

PubMed1995

Identification and synthesis of chemotactic tripeptides from alkali-degraded whole cornea. A study of N-acetyl-proline-glycine-proline and N-methyl-proline-glycine-proline.

PURPOSE: To identify and synthesize the polymorphonuclear leukocyte chemoattractant(s) released from alkali-degraded corneas. METHODS: Corneas were degraded in 1.0 N NaOH, neutralized, ultrafiltered, and dialyzed. The final active ultrafiltrate was subjected to high-performance liquid chromatography on a Protein PAK I-60 column. The most active fractions were further separated on a mu-Bondapak-C18 and I-60 column in sequence. RESULTS: Fraction 38 from the final I-60 column associated with a 210-nm absorption peak and elicited a polarization and chemotactic response from polymorphonuclear leukocytes. The loss of polarization activity in fraction 38 after exposure to prolidase suggests that this peptide contains a Pro-X (X = amino acid) peptide bond. The amino acid composition of fraction 38 was 35% glycine and 53% proline. Peptide sequence analysis was unable to establish a primary sequence even though Picotag analysis showed the presence of large amounts of the two amino acids. Mass spectrometry revealed only two molecular species of 312 MWt and 284 MWt. Tripeptides were synthesized using all possible amino acid permutations of 2 Pro and 1 Gly and tested in the polarization and chemotactic assays. These techniques demonstrated that n-acetyl-Pro-Gly-Pro, and to a lesser degree n-methyl-Pro-Gly-Pro, were the only synthetic tripeptides with activity similar to the purified chemoattractant. CONCLUSIONS: The data show that the chemotactic peptides, purified from alkali-degraded whole cornea and confirmed with identical synthetic tripeptides, are N-acetyl-Pro-Gly-Pro and N-methyl-Pro-Gly-Pro. Although a number of proteins contain the Pro-Gly-Pro sequence, large amounts of collagen in the cornea suggest this as a major source. The small size and hydrophilic nature of these chemoattractants are predictive of a high degree of diffusibility. These chemoattractants are likely to play a major role in the early neutrophil response after an alkali injury.

Amino Acid Sequence↗

PubMedDate not supplied

Adaptation of inner medullary collecting duct vacuolar H-adenosine triphosphatase to chronic acid or alkali loads in the rat.

Acidosis increases and alkalosis decreases proton secretion in the inner medullary collecting duct (IMCD). We examined the mechanism of this adaptation by studying the immunocytochemical distribution of the vacuolar H-adenosine triphosphatase (ATPase) in the IMCD from rats subjected to acid or alkali loads for a mean duration of 4 and 9 days. For immunocytochemical staining, a monoclonal antibody to the 31-kD subunit of the bovine kidney vacuolar H-ATPase was used. Intercalated cells were present only in the initial IMCD, and the principal cells and IMCD cells showed no appreciable H-ATPase staining under any experimental conditions. We found significant adaptive changes in the distribution of H-ATPase in the intercalated cells of the IMCD. H-ATPase staining in acid-loaded rats shifted from cytoplasmic vesicles to apical plasma membrane, whereas in alkali-loaded rats cytoplasmic vesicular staining was enhanced and staining of plasma membrane disappeared. These adaptive changes were most prominent on day 4 of acid-loaded and days 4 and 9 of alkali-loaded rats. Our results indicate that translocation of the H-ATPase pump between cytoplasmic vesicles and apical plasma membrane of the intercalated cells is an important mechanism is adaptation of the IMCD to chronic acid base perturbations.

Acidosis↗

PubMed1993

Studies on the reduction of aortic calcification by alkali citrates in an ex vivo tissue preparation in the rat.

The effect of orally administered alkali citrates on the calcification of arterial vessel was studied in the rat. Freshly dissected aortic segments were placed in Millipore diffusion chambers and grafted intraperitoneally. Within 21 days calcification of the media had developed. Under treatment with 2.1 mmol citrate per animal and day a significant decrease in histologically detectable calcification areas occurred, as assessed by greatest thickness and longitudinal expansion. This effect was more pronounced with potassium citrate and potassium sodium citrate, and less marked with sodium citrate. The calcium and phosphorus content of aortic tissue remained unchanged, but magnesium increased significantly. The spheroid particles deposited in the media were characterized in more detail by electron microscopy and elemental microanalysis, X-ray diffraction, and determination of the molar calcium-phosphorus ratio. The combined data suggest that in the model selected for studying biocalcification not mature hydroxyapatite but some precursor of this substance is deposited, and that in animals receiving alkali citrate treatment deposition of amorphous calcium phosphate is likely. It is concluded that in the ex vivo aortic wall preparation oral alkali citrates a) bring about a reduction in calcification areas in the media layer, b) impair the maturation of hydroxyapatite and its deposition in the arterial tissue; c) promote the accumulation of magnesium. Whether these results are of significance for the calcification of arteries in situ and treatment regimens is unknown.

Animals↗

PubMed1997

Acute poisoning due to alkalis used during industrial cleaning of soft drinks' glass containers: a case report.

Corrosive alkalis are used in the soft drink and beer industries for the cleaning of the non-disposable glass containers using several different methods. It is well understood that complete cleaning of these vessels by multiple and well-organized rinsing is an absolute necessity. In cases of disturbance of this process, some residuals of alkaline agents may be retained in the glass containers, causing severe health risks to consumers. This case of acute poisoning due to caustic alkalis concerns a young woman who consumed carbonated lemonade from a non-disposable glass container. Clinical signs and symptoms and the treatment of the affected woman are described. Toxicological analysis of the soft drink consumed led to the detection, identification and quantitative determination of the presence of the alkalis.

Adult↗

PubMedDate not supplied

Hypercalcemia and alkalosis due to the milk-alkali syndrome: a case report and review.

At one time, when antacids were the primary medical means of treating peptic ulcer disease, the milk-alkali syndrome was not an uncommon cause of hypercalcemia. The simultaneous occurrence of hypercalcemia, alkalosis, and renal failure, in conjunction with the appropriate history of ingestion fof antacids, was suggestive of the syndrome. With the advent of antisecretory therapy, however, the milk-alkali syndrome has become an uncommon diagnosis. I report a case of milk-alkali syndrome and review the history of this syndrome as reported in the medical literature. Contemporary reports have focused on understanding the pathophysiology of the syndrome. Recent series have identified a shifting demographic profile, as increasing numbers of elderly women consume calcium carbonate as an anti-osteoporosis measure.

Aged↗

PubMed1996

[An experimental study on immune mechanism after alkali burn in the anterior segment of rabbit eye].

OBJECTIVE: To study the immunologic mechanism of corneal ulceration after alkali burn. METHODS: 55 rabbits with alkali burn in right eye were randomly divided into two groups. In group I (31 animals), the level of circulating immune complex (CIC), the rate of red blood cell C3b receptor complex rosette (RBC-C3bRR) and immune complex rosette (RBC-ICR) were measured respectively at 7, 14, 21, 35, 49 days after alkali burn. In Group 2 (24 animals), the immune complex was detected by means of immunofluorescence (IF) and immunogold-silver staining (IGSS) in burned tissues at 21 days after burn. Histopathologic changes were also observed under light microscope. RESULTS: CIC, the rate of RBC-C3bRR and RBC-ICR were markedly increased 14 to 21 days after burn. In the mean time, the deposition of immune complex was found in burned tissues and the accumulation of polymorphonuclear leukocyte (PMN) was observed at the base of corneal ulcer. CONCLUSIONS: The immune mechanism indeed participates in the pathogenesis of corneal ulceration and also aggravates the progress of ulceration on the base of chemical injury.

Animals↗

PubMed1998

Injection of chemoattractants into normal cornea: a model of inflammation after alkali injury.

PURPOSE: The objective of this study was to establish and characterize the invasion of polymorphonuclear leukocytes (PMNs) into a normal cornea after intrastromal injection of the tripeptide chemoattractants generated from alkali-degraded corneas. METHODS: The following samples were injected into the midstroma of normal rabbit corneas: ultrafiltered tripeptide chemoattractants (N-acetyl-proline-glycine-proline and N-methyl-proline-glycine-proline) generated from alkali-degraded corneas, synthetic N-acetyl-PGP, positive control (leukotriene B4 [LTB4]), or negative control (Hanks' balanced salt solution [HBSS]). Timed responses of PMN infiltration were established for effective concentrations of LTB4 or the ultrafiltered chemoattractants. RESULTS: All intrastromal injections resulted in the immediate development of an edematous disc that was 10 mm in diameter. The lesion essentially had cleared in the HBSS-injected eyes by 8 hours, and histologic sections revealed minimal numbers of PMNs in the cornea or limbal tissue. The injection of LTB4 or the ultrafiltered tripeptide chemoattractants induced peak numbers of PMNs within the stroma at 8 hours, subsiding by 16 hours. Seventy units of ultrafiltered chemoattractants yielded a strong PMN response, similar to 1 X 10(-5) M LTB4. The highest concentration of ultrafiltered chemoattractants (350 U) produced a severe PMN response that was characterized by a solid sheet of neutrophils surrounding the injection site. The injection of synthetic N-acetyl-PGP (2 X 10(-4) M) produced a marked PMN response. CONCLUSIONS: PMN invasion of the normal cornea after the injection of the ultrafiltered tripeptide chemoattractants or the synthetic N-acetyl-PGP mimicked early PMN infiltration in the alkali-injured eye, confirming the importance of this chemoattractant as an inflammatory mediator.

Animals↗

PubMed1978

Effect of topical corticosteroids on ulceration in alkali-burned corneas.

Dexamethasone sodium phosphate was administered topically to one eye of rabbits with bilateral alkali corneal burns, and saline solution was administered to the contralateral eye. Topical steroids were also administered in animals with moderate corneal ulcers and were found to enhance the severity of ulceration when given during the second and third weeks following the burn. If the corticosteroids were given daily in the first six days or in the fourth and fifth weeks following the burn, they did not have an adverse effect on the cornea. Corticosteroids can be used intensively during the first week following an alkali burn, without increasing the risk of corneal melting. The mechanism for the enhancement of corneal ulceration is not a direct augmentation of collagenase activity, but probably involves the inhibition of repair processes.

Alkalies↗

PubMed1985

Ocular blood flow after experimental alkali burns and prostaglandin administration.

Ocular blood flow was determined using radioactive strontium 85 microspheres after an alkali (sodium hydroxide [NaOH]) burn to the eye. With 20 microL of NaOH, blood flow was significantly increased in the iris, ciliary processes, and choroid from two through four hours. This correlated well with the sustained increase in intraocular pressure (IOP) seen after a 20-microL burn. A 50-microL burn increased blood flow at one hour, but it returned toward normal levels beyond two hours. In general terms, there appeared to be a meaningful correlation between IOP changes and altered blood flow following ocular alkali burns. The blood flow changes paralleled those occurring after the topical application of prostaglandins and supported the concept that ocular blood flow dynamics are mediated by prostaglandins.

Alkalies↗

PubMed1999

Control of pH in large-scale, free suspension animal cell bioreactors: alkali addition and pH excursions.

It is likely that, in the future, animal cell cultures of a higher cell density and/or cell lines with higher specific oxygen demands will be available. Such developments will lead to the need for improved homogeneity in the bioreactor and a greater supply of nutrients. The accompanying significant increase in CO(2) production and accumulation and the resulting reduction in pH are also important implications for process engineering. Such pH reduction is typically controlled by the addition of sodium carbonate. Previous studies using flow visualization mimicking the operating conditions in a typical plant-scale reactor showed potentially cell-damaging regions within it due to pH excursions. This paper confirms the existence of these excursions by pH measurements in the alkali addition zone. It also identifies the accumulation of alkali in a region of poor local liquid homogenization as a serious scale-up problem and shows how a change in the addition point significantly reduces it.

Alkalies↗

PubMed1997

The influence of alkali and alkaline earths on the working range for bioactive glasses.

Viscosity-temperature dependence has been investigated for glasses in a system where bioactive compositions are found. A glass is called bioactive when living bone can bond to it. In this work, high-temperature microscopy was used to determine viscosity-temperature behaviour for 40 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2. The silica content in the glasses was 39-70 wt% % All glasses containing < 54 mol % SiO2 devitrified during the viscosity measurements. Generally, glasses that devitrified contained more alkali but less alkaline earths than glasses with a large working range. A working range is the temperature interval at which forming of a glass can take place. This temperature interval can, for bioactive glasses, be enlarged by decreasing the amount of alkali, especially Na2O, in the glass and by increasing the amount of alkaline earths, especially MgO. Optionally, B2O3 and P2O5 can be added to the glass. An enlarged working range is a prerequisite for an expanded medical use of bioactive glasses as e.g., sintered and blown products, and fibers.

Alkalies↗

PubMed2004

Yeast plasma membrane Ena1p ATPase alters alkali-cation homeostasis and confers increased salt tolerance in tobacco cultured cells.

In plants, the plasma membrane Na(+)/H(+) antiporter is the only key enzyme that extrudes cytosolic Na(+) and contributes to salt tolerance. But in fungi, the plasma membrane Na(+)/H(+) antiporter and Na(+)-ATPase are known to be key enzymes for salt tolerance. Saccharomyces cerevisiae Ena1p ATPase encoded by the ENA1/PMR2A gene is primarily responsible for Na(+) and Li(+) efflux across the plasma membrane during salt stress and for K(+) efflux at high pH and high K(+). To test if the yeast ATPase would improve salt tolerance in plants, we expressed a triple hemagglutinin (HA)-tagged Ena1p (Ena1p-3HA) in cultured tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY2) cells. The Ena1p-3HA proteins were correctly localized to the plasma membrane of transgenic BY2 cells and conferred increased NaCl and LiCl tolerance to the cells. Under moderate salt stress conditions, the Ena1p-3HA-expressing BY2 clones accumulated lower levels of Na(+) and Li(+) than nonexpressing BY2 clones. Moreover, the Ena1p-3HA expressing BY2 clones accumulated lower levels of K(+) than nonexpressing cells under no-stress conditions. These results suggest that the yeast Ena1p can also function as an alkali-cation (Na(+), Li(+), and K(+)) ATPase and alter alkali-cation homeostasis in plant cells. We conclude that, even with K(+)-ATPase activity, Na(+)-ATPase activity of the yeast Ena1p confers increased salt tolerance to plant cells during salt stress.

Adenosine Triphosphatases↗

PubMed2006

The importance of alkali cations in the [{RuCl2(p-cymene)}2]-pseudo-dipeptide-catalyzed enantioselective transfer hydrogenation of ketones.

We studied the role of alkali cations in the [{RuCl2(p-cymene)}2]-pseudo-dipeptide-catalyzed enantioselective transfer hydrogenation of ketones with isopropanol. Lithium salts were shown to increase the enantioselectivity of the reaction when iPrONa or iPrOK was used as the base. Similar transfer-hydrogenation systems that employ chiral amino alcohol or monotosylated diamine ligands are not affected by the addition of lithium salts. These observations have led us to propose that an alternative reaction mechanism operates in pseudo-dipeptide-based systems, in which the alkali cation is an important player in the ligand-assisted hydrogen-transfer step. DFT calculations of the proposed transition-state (TS) models involving different cations (Li+, Na+, and K+) confirm a considerable loosening of the TS with larger cations. This loosening may be responsible for the fewer interactions between the substrate and the catalytic complex, leading to lower enantiodifferentiation. This mechanistic hypothesis has found additional experimental support; the low ee obtained with [BnNMe3]OH (a large cation) as base can be dramatically improved by introducing lithium cations into the system. Also, the complexation of Na+, K+, and Li+ cations by the addition of [15]crown-5 and [18]crown-6 ethers and cryptand 2.1.1 (which selectively bind to these cations and, thus, increase their bulkiness), respectively, to the reaction mixture led to a significant drop in the enantioselectivity of the reaction. The lithium effect has proved useful for enhancing the reduction of different aromatic and heteroaromatic ketones.

Alkalies↗

PubMed2002

Surface modification by alkali and heat treatments in titanium alloys.

Pure titanium and titanium alloys are normally used for orthopedic and dental prostheses. Nevertheless, their chemical, biological, and mechanical properties still can be improved by the development of new preparation technologies. This has been the limiting factor for these metals to show low affinity to living bone. The purpose of this study is to improve the bone-bonding ability between titanium alloys and living bone through a chemically activated process and a thermally activated one. Two kinds of titanium alloys, a newly designed Ti-In-Nb-Ta alloy and a commercially available Ti-6Al-4V ELI alloy, were used in this study. In this study, surface modification of the titanium alloys by alkali and heat treatments (AHT), alkali treated in 5.0M NaOH solution, and heat treated in vacuum furnace at 600 degrees C, is reported. After AHT, the effects of the AHT on the bone integration property were evaluated in vitro. Surface morphologies of AHT were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Chemical compositional surface changes were investigated by X-ray diffractometry (XRD), energy dispersive spectroscopy (EDS), and auger electron spectroscopy (AES). Titanium alloys with surface modification by AHT showed improved bioactive behavior, and the Ti-In-Nb-Ta alloy had better bioactivity than the Ti-6Al-4V ELI alloy in vitro.

Alkalies↗

PubMed2001

Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post-source decay matrix-assisted laser desorption/ionization mass spectrometry.

A post-source decay matrix-assisted laser desorption/ionization mass spectrometric (PSD-MALDI-MS) study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, is reported. The fragmentations of rutin were performed by selecting the [R + Cat]+ peaks for PSD, where R represents a rutin molecule and Cat an alkali metal ion (Li+, Na+, K+). The PSD-MALDI mass spectra showed, depending on Cat, different fragmentation patterns with respect to both the quality and quantity of the fragment ions formed. The intensity of fragmentation decreased in the order Li+ > Na+ > K+. The fragmentation mechanism and an explanation for the observed differences are suggested.

Cations↗

PubMed2006

Electrospray tandem mass spectrometry of alkali-cationized BocN-carbo-alpha,beta- and -beta,alpha-peptides: Differentiation of positional isomers.

Dissociation pathways of a series of alkali-cationized hybrid peptides, viz., Boc-alpha,beta- and -beta,alpha-carbopeptides, synthesized from C-linked carbo-beta3-amino acids [Caa (S)] and alpha-alanine (L-Ala), have been investigated by electrospray ionization tandem mass spectrometry. The positional isomers (six pairs) of the cationized alpha,beta- and beta,alpha-peptides can be differentiated by the collision-induced dissociation (CID) spectra of their [M + Cat-Boc + H]+ ions which give characteristic series of alkali-cationized C- (x(n)+, y(n)+, z(n)+) and N-terminal (a(n)+, b(n)+, c(n)+) ions. Another noteworthy difference is cationized beta,alpha-peptides eliminate a molecule of ammonia whereas this pathway is absent for alpha,beta-peptides. This is useful for identifying the presence of a beta-amino acid at the N-terminus. The CID spectra of [M + Cat-Boc + H]+ ions of these peptide acids show abundant rearrangement [b(n) + 17 + Cat]+ (n = 1 to n-1) ions which is diagnostic for distinguishing between alpha- and beta-amino acid at the C-terminus. MS(n) experiments of [b(n) + Li-H]+ ions from these hybrid peptides showed the loss of CO and 72 u giving rise to [a(n) + Li-H]+ and cationized nitrile product ions which render support to earlier proposals that b(n)+ or [b(n) + Cat-H]+ ions have protonated or cationized oxazolinone structures, respectively.

Alkalies↗