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At least 793 records · Page 44Linked to original sources
PubMed1982

Influence of systemic ascorbic acid treatment on metabolite levels after regeneration of the corneal epithelium following mild alkali burns.

Between 6 and 16 days after mild alkali burns of rabbit eyes, the aqueous humor and corneal stroma ascorbic acid levels were decreased in the untreated animals. Systemic treatment with ascorbate 0.5 g/kg body weight injected daily subcutaneously) raised the reduced ascorbic acid levels to twice the normal values in the aqueous humor, but those of the corneal stroma increased only slightly and remained far below the normal levels. The systemic ascorbate treatment did not improve the healing rate of the corneal epithelium, but increased adenosine triphosphate and diphosphate levels as well as the ATP/ADP ratio of the glutathione was shifted to a more reduced state.

Alkalies↗
PubMed2026

Development of molecular markers associated with saline-alkali tolerance in rapeseed (Brassica napus L.).

A total of 947 saline-alkaline tolerance-related molecular markers and a 5K cGPS genotyping chipwere developed, providing practical tools for marker-assisted selection and molecular design breeding of saline-alkaline-tolerant rapeseed. Rapeseed (Brassica napus L.) has relatively strong tolerance to saline-alkaline stress and shows great potential for the sustainable utilization and improvement of saline-alkaline soils. However, the breeding of highly tolerant cultivars still mainly depends on conventional hybridization combined with phenotype-based selection, which constrains breeding efficiency. In this study, previously reported saline-alkaline tolerance-related genes from rapeseed, rice, maize, wheat, sorghum, and Arabidopsis were collected. Candidate gene-based association analysis enabled the development of molecular markers and a genotyping chip. A total of 483 significantly associated genes were identified, among which 355 genes contained favorable haplotypes. Molecular markers were successfully developed for 275 genes, including 746 KASP and 201 InDel marker pairs, and four marker pairs were randomly selected for validation. In addition, a 5K cGPS liquid-phase chip (HZSW-cGPS-BRNAP-04), was developed and showed a high call rate and excellent reproducibility in genotyping. These markers and the chip are expected to improve the breeding efficiency of saline-alkaline-tolerant rapeseed cultivars. Overall, this study provides useful tools for early-generation evaluation and marker-assisted selection (MAS), and provides a foundation for molecular design breeding of saline-alkali-tolerant rapeseed.

Brassica napus↗
PubMed2001

Renal cortical calcification in syngeneic intact rats and those receiving an infrarenal thoracic aortic graft: possible etiological roles of endothelin, nitrate and minerals, and different preventive effects of long-term oral treatment with magnesium, citrate and alkali-containing preparations.

Renal cortical nephrocalcinosis (C-NC) is a rare disorder of uncertain etiology. Using highly inbred (syngeneic) male Lewis rats, we describe the spontaneous occurrence of histologically detectable C-NC in sham operated control rats (Sham; n=12), its aggravation following grafting of the ascending thoracic aorta from a donor rat to the infrarenal aorta of a recipient (ATx; n=12), and differences in C-NC inhibition after 12 weeks of oral administration of magnesium (Mg), citrate and alkali. C-NC is characterized by Kossa-positive areas located in cells of the proximal tubule close to blood vessels and also, to a lesser extent, within glomeruli. After ATx there was vascular overproduction of endothelin (ET-1) but decreased production of nitrate; in renal cortical tissue there was an excess of calcium over Mg and phosphorus and oxalate over citrate. In plasma there was an increase in calcium and creatinine within the normal range. Calcification of tubular cells was eliminated by a preparation containing potassium, sodium and bases (from citrate degradation and bicarbonate) in addition to Mg. Less effective than the latter was Mg-potassium citrate and least effective, Mg citrate. The former treatment also normalized calcemia and urinary nitrate, but only incompletely suppressed ET-1 and had no significant effect on glomerular calcification or tissue and urinary oxalate. Urinary ET-1 excess appeared directly related to the cortical tissue calcium/Mg ratio, and urinary excretion of Mg, citrate and total protein appeared to be inversely related to the severity of C-NC. It was concluded that (1) the highly inbred rat is prone to precipitation of calcium phosphate in the renal cortex; (2) this type of C-NC occurs in close proximity to and within renal vascular tissue and is associated with an imbalance of vasoconstrictors and vasodilators of endothelial origin; (3) effective inhibition of C-NC can be achieved by an alkalinizing combination of Mg, potassium, sodium and citrate, underscoring its utility in the prophylaxis of pathological calcium phosphate deposition. The significance of these findings for the etiology and treatment of clinical disorders with renal and vascular calcification is uncertain and requires further investigation.

Alkalies↗
PubMed1997

Conductometric properties of human erythrocyte membranes: dependence on haematocrit and alkali metal ions of the suspending medium.

The electrical properties of the cytoplasmatic membrane of human erythrocyte cells have been evaluated by means of dielectric spectroscopy measurements in the radiowave frequency range, using the so-called "suspension method". Measurements have been carried out at different volume fractions of the corpuscular phase (the cell haematocrit) in order to investigate the influence of the cell-cell interactions on the electrical parameters (the membrane permittivity epsilon and the membrane conductivity sigma) of the cell membrane and a set of new values are proposed. Moreover, the influence of different alkali metal ions (Na+, K+, Cs+, Li+) on the ion permeation properties of the membrane are investigated and the structural alterations in the membrane organized briefly discussed.

Adult↗
PubMed2006

Pediatric dyspnea caused by supraglottic stenosis: a rare complication of alkali corrosive injury.

Acquired supraglottic stenosis is a rare, but potential late sequela of corrosive injury, usually occurring 1 to 2 months after the initial trauma. The presentation may be delayed in children and is potentially lethal. We describe two pediatric patients, aged 31 and 16 months, who developed progressive inspiratory stridor and hoarseness about 2 months after accidental alkali ingestion. Fiberoptic laryngoscopy showed supraglottic stenosis. Intubation was achieved with a very small endotracheal tube under fiberoptic laryngobronchoscopic guidance prior to general anesthesia. Both patients successfully underwent CO(2) laser treatment under direct laryngoscopic guidance. There has been no case of recurrence reported after 1 year of follow-up other than a thin membranous scar in one case at the 3rd month of follow-up, which was easily dealt with by bronchoscopy dilatation. For such patients, monthly laryngoscopic examinations are advisable after alkaline corrosive injury for a minimum of 6 months. Prompt diagnosis and early airway intervention can reduce the need for tracheostomy and decrease the mortality rate.

Alkalies↗
PubMed1996

Block of BK (maxi K) channels of rat pituitary melanotrophs by Na+ and other alkali metal ions.

The block of large-conductance calcium-activated potassium (BK) channels by internal and external alkali metal ions was studied in adult rat melanotrophs. Internal but not external 20 mM Na+ produced a strongly voltage-dependent, flickery block that was well-fitted to the Woodhull model by using a value of 140 mM for the dissociation rate constant at 0 mV [Kd(0)] and an equivalent valence (zdelta) of 0.9. At a concentration of 20 mM external K+, Cs+ and Rb+, but not Li+, caused a rightward shift of the voltage dependence of the intracellular Na+ (Na+i ) block. This effect of K+, Cs+ and Rb+ was modelled by an equilibrium knock-out mechanism in which the block-relieving ion binds to a site located within the voltage field and consequently increases the off-rate of Na+. Internal Li+ caused little or no block whereas internal Cs+ caused a voltage-dependent block [Kd(0) approximately 150 mM]. Flickery channel block observed in cell-attached patches was consistent with a cytoplasmic Na+ activity between 1 and 10 mM.

Animals↗
PubMed2005

Role of the alkali labile sites, reactive oxygen species and antioxidants in DNA damage induced by methylated trivalent metabolites of inorganic arsenic.

In the last decade arsenic metabolism has become an important matter of discussion. Methylation of inorganic arsenic (iAs) to monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) is considered to decrease arsenic toxicity. However, in addition to these pentavalent metabolites, the trivalent metabolites monomethylarsonous (MMA(III)) and dimethylarsinous acid (DMA(III)) have been identified recently as intermediates in the metabolic pathway of arsenic in cultured human cells. To examine the role of oxidative damage in the generation of DNA strand breaks by methylated trivalent arsenic metabolites, we treated human lymphocytes with both metabolites at non-cytotoxic concentrations. We further tested whether these effects are sensitive to modulation by the antioxidants ascorbate (Vitamin C) and selenomethionine (Se-Met). Both trivalent metabolites produced oxidative stress related DNA damage, consisting of single strand breaks and alkali-labile sites, with MMA(III) being more potent at low concentrations than DMA(III). Neither MMA(III) nor DMA(III) induced DNA-double strand breaks. The oxidative stress response profiles of the metabolites were parallel as determined by lipid peroxidation induction. MMA(III) induced peroxidation from the lowest concentration tested, while effects of DMA(III) were apparent only at concentrations above 10 muM. The antioxidant Se-Met exhibited a more pronounced inhibition of trivalent arsenic metabolite-induced oxidative-DNA damage than did vitamin C. The present findings suggest that DNA damage by methylated trivalent metabolites at non-cytotoxic concentrations may be mediated by a mix of reactive oxygen and nitrogen oxidized species.

Adult↗
PubMed2005

An alkali-inducible flotillin-like protein from Bacillus halodurans C-125.

Flotillins are markers of lipid microdomains, and have emerged as a key concept in cellular biology. However, it remains unclear whether flotillin proteins exist in prokaryotic cells. The amino acid sequence of the BH3500 protein from Bacillus halodurans was 30% identical to that of flotillin-1. Motif analysis revealed that several specific residues (SPFH and flotillin domains, an AEA-repeat structure) and five potential phosphorylation sites are conserved in the BH3500 protein. In addition, the BH3500 protein was found to possess two transmembrane-spanning domains at the N-terminus, which is consistent with the common properties of flotillin-1. The BH3500 protein was detected in the Triton-insoluble, buoyant membrane fraction of B. halodurans by mass spectrometry and Western blotting. Interestingly, BH3500 was expressed strongly in alkaline conditions at both transcriptional and translational levels, which implies that it is one of the alkali-inducible proteins.

Alkalies↗
PubMed1975

Aqueous humor pH changes after experimental alkali burns.

Following application of 2N sodium hydroxide, or 8.1N ammonium hydroxide to rabbit cornea, the aqueous humor pH reached a maximum of 10.2, 11.9, and 12 within six minutes following 20-, 50-, and 100-mu1 sodium hydroxide burns, respectively; after two hours the pH had fallen to 8.5, 10, and 10.5. The maximum rise following application of 100-mu1 of ammonium hydroxide was 10.8, declining to about 9 at two hours. The fall in pH following a 100-mu1 sodium hydroxide burn was not greatly influence by external lavage. However, the pH was significantly lowered (12 to 10) by paracentesis alone and further reduced by immediate or delayed intracameral administration of phosphate buffer. On the basis of these results moderately severe and severe alkali burns of the eye should be treated by paracentesis and if possible with anterior chamber reformation with a sterile solution.

Alkalies↗
PubMed1983

Determination of protein-bound phosphate by continuous flow analysis: automated procedure for the determination of alkali-labile phosphate.

A method is described for the specific, quantitative determination of protein-bound phosphorus by a continuous flow procedure using a Technicon AutoAnalyzer. It is based on the exceptional alkali lability of serine phosphate linkages to beta-elimination when the serine residues are present in a polypeptide chain. The results are reproducible within about 3, 5, or 10%, respectively, when the analytical sample contains about 100, 10, or 3 nmol of protein-bound P. The presence of less than 1 nmol protein-bound P can be detected. The method tolerates wide variations of the pH and ionic composition of the sample, making it suitable for the automatic, serial analysis of chromatographic effluent fractions. Low-molecular-weight phosphomonoesters, ribonucleic acid (phosphodiester), and nucleotide phosphates (pyrophosphate) do not react measurably. Carboxyphenyl phosphate is partially hydrolyzed (10-15%). In contrast, the release of P from various phosphoproteins is quantitative.

Alkalies↗
PubMed1990

Alkali-soluble and insoluble fluoride in erupted and unerupted sound enamel of human third molars in vivo.

The amounts of firmly and loosely bound fluoride were determined in sound enamel of unerupted and erupted teeth which had been exposed in vivo for 1-16 yr to brushing at least once a day, and occasionally to mouth rinsing and the application of sealers. Enamel was sampled by an acid-etch procedure, and the fluoride levels were measured with an adapted fluoride ion-selective electrode. Unerupted enamel was etched significantly (p less than 0.05) deeper than erupted enamel up to a depth of at least 8 microns. Significant differences (p less than 0.05) were found between the mean enamel fluoride concentrations of unwashed and alkali-washed, erupted teeth up to a depth of at least 3 microns and also between unwashed or washed, erupted versus unwashed or washed, unerupted teeth. At a depth of 3 microns, the fluoride treatments of enamel had increased the total amount of fluoride by approx. 78% of which approx. 53% was loosely bound fluoride (like CaF2) and 47% firmly bound (like fluorapatite). No increase in sound enamel fluoride as a result of topical treatments over a period of up to 16 yr could be found at a level deeper than 20 microns.

Acid Etching, Dental↗
PubMed1983

Alkali lability of deoxyribonucleic acid that contains adenine arabinoside.

We have demonstrated previously that 9-beta-D-arabinofuranosyl adenosine (ara-A), like 1-beta-D-arabinofuranosyl cytosine (ara-C), incorporates exclusively into DNA, not RNA [Kufe et al., Cancer Res. 43, 2000 (1983)]. We have also demonstrated that (ara-C)DNA is degraded by alkali [Major et al., Biochem. Pharmac. 31, 861 (1982)], suggesting a structural instability of this abnormal nucleic acid. These findings have been extended by investigating the effects of various alkaline conditions on ara-A and (ara-A)DNA. The results indicate that the nucleoside was degraded under stringent conditions (0.4 M NaOH, 0.5 hr, 100 degrees) and that a similar effect occurred following exposure of (ara-A)DNA. The results also indicate that milder alkaline conditions (0.4 M NaOH, 6 hr, 37 degrees) resulted in strand scission of (ara-A)DNA at the 3'-carbon of the incorporated arabinosyl sugar without degradation of the ara-A moiety itself. These findings may be useful when attempting to purify (ara-A)DNA and confirm the structural instability of arabinosyl-containing DNA.

Alkalies↗
PubMed1990

A comparison of the results of sequential hydrazinolysis-nitrosation and alkali-mediated cleavage-nitrosation of the O-linked oligosaccharides of gastric mucus glycoproteins.

Analysis of the oligosaccharides released from pig gastric mucus glycopolypeptides by hydrazinolysis showed that degradation had occurred. Nitrosation of the products followed by reduction gave a mixture that had a low content of 2,5-anhydro-D-talitol, which implied destruction of much of the terminal reducing 2-amino-2-deoxy-D-galactose. Under the conditions of hydrazinolysis, cellobiose was largely unchanged but laminaribiose gave a complex mixture that probably contained glucose hydrazone (13C-n.m.r. data). In order to avoid degradation, the hydrazinolysis-nitrosation sequence should be applied to the reduced oligosaccharides released on cleavage with alkali.

Alkalies↗
PubMed1993

Mode of action of (1-->4)-beta-D-arabinoxylan arabinofuranohydrolase (AXH) and alpha-L-arabinofuranosidases on alkali-extractable wheat-flour arabinoxylan.

Arabinoxylan-derived oligosaccharides were treated with (1-->4)-beta-D-arabinoxylan arabinofuranohydrolase (AXH) and two types of alpha-L-arabinofuranosidase, A and B. Analysis of reaction products by high performance anion-exchange chromatography indicated the removal of arabinofuranosyl groups from singly substituted xylopyranosyl residues. In addition, differences in the specificity of these enzymes towards the various differently substituted oligosaccharides were observed. 1H NMR spectroscopy and methylation analysis of alkali-extractable wheat-flour arabinoxylan treated with AXH confirmed the specificity of AXH towards (1-->3)-linked arabinofuranosyl groups on singly substituted xylopyranosyl residues. With these techniques, alpha-L-arabinofuranosidase B was found to cause minor changes in (1-->2)- and (1-->3)-linked arabinofuranosyl groups on doubly substituted xylopyranosyl residues.

Alkalies↗
PubMed1993

Mode of action of the xylan-degrading enzymes from Aspergillus awamori on alkali-extractable cereal arabinoxylans.

Alkali-extractable cereal arabinoxylan and oligosaccharides of known structure derived from it by enzymic hydrolysis were treated with endo-(1-->4)-beta-D-xylanases I and III from Aspergillus awamori CMI 142717 and the digests subjected to analysis by high performance anion-exchange chromatography. Clear differences in the mode of action of the two endo-(1-->4)-beta-D-xylanases were observed. When counting from the reducing end, at least one unsubstituted xylopyranosyl residue adjacent to singly substituted xylopyranosyl residues or two unsubstituted xylopyranosyl residues adjacent to doubly substituted xylopyranosyl residues cannot be removed by endo-(1-->4)-beta-D-xylanase I. At least two unsubstituted xylopyranosyl residues adjacent to singly or doubly substituted xylopyranosyl residues cannot be removed by endo-(1-->4)-beta-D-xylanase III. beta-D-Xylosidase from the same xylanolytic system was able to remove terminal xylopyranosyl residues from the nonreducing end of branched oligosaccharides only when two contiguous unsubstituted xylopyranosyl residues were present adjacent to singly or doubly substituted xylopyranosyl residues.

Alkalies↗
PubMed1993

Characterisation by 1H NMR spectroscopy of oligosaccharides derived from alkali-extractable wheat-flour arabinoxylan by digestion with endo-(1-->4)-beta-D-xylanase III from Aspergillus awamori.

Alkali-extractable wheat-flour arabinoxylan, treated with endo-(1-->4)-beta-D-xylanase III from Aspergillus awamori CMI 142717, was fractionated by Bio-Gel P-2 size exclusion chromatography at 60 degrees C. Column fractions, corresponding to oligosaccharides with degrees of polymerisation from 5 to 10, were collected, and subfractionated by high performance anion-exchange chromatography on CarboPac PA-1. The structures of the oligosaccharides thus obtained were elucidated by 1H NMR spectroscopy, showing chains of (1-->4)-linked beta-D-xylopyranosyl residues differently substituted at O-3 and/or O-2,3 with alpha-L-arabinofuranosyl groups. The structures were different from those obtained with endo-(1-->4)-beta-D-xylanase I of the same xylanolytic enzyme system.

Alkalies↗
PubMed1989

Hyaluronate in healing of corneal alkali wound in the rabbit.

The effect of topically applied 1% and 2% sodium hyaluronate was studied on the healing of a standardized rabbit corneal alkali wound. The healing of the epithelium, the stroma, and the endothelium was evaluated separately by applying quantitative methods. The healing was followed for 8 weeks. Both 1% and 2% sodium hyaluronate have a statistically significant positive influence on the epithelial re-surfacing, especially during the late healing phase. Furthermore, sodium hyaluronate has a positive healing influence on the stromal healing at a certain time interval during the observation period. This was reflected as a better maintained stromal dry mass level compared to control. The stromal healing was parallel to a faster re-surfacing of the endothelium.

Administration, Topical↗