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At least 523 records · Page 29Linked to original sources
PubMed1996

Performance of broiler chicks fed on alkali-treated neem (Azadirachta indica) kernel cake as a protein supplement.

1. An experiment was conducted to evaluate growth and nutrient efficiency of broiler chicks from 3 to 42 d fed on diets containing alkali-treated neem (Azadirachta indica A. juss) kernel cake (NKC) as a protein supplement in place of peanut meal (PNM). 2. NKC was treated with sodium hydroxide at 10 (ANKC 1) or 20 g (ANKC 2)/kg and incorporated into the test diets at 135 or 300 g/kg to replace 50 (low-L) or 100 (High-H)% of the PNM protein of the reference diet. 3. Despite comparable retentions of dry matter and total carbohydrate on L-ANKC 1 and 2, fibre on L-and H-ANKC 2 and nitrogen, calcium and acid detergent fibre on all experimental diets compared to the retentions of chicks on the reference diet, only the chicks fed L-ANKC 2 were found to grow and utilise food as well as those on the reference diet. 4. The activities of serum alkaline phosphatase on H-ANKC 1 and alanine amino transferase on all test diets were depressed (P < 0.05), but the activity of serum aspartate amino transferase, total erythrocyte count and concentration of blood haemoglobin and urea were similar in all chicks. 5. No significant differences were noticed in the qualitative and quantitative characteristics of the meat of chicks fed on the reference diet and on diets incorporating ANKC at the lower concentrations. Feeding ANKC protein did not impart any untoward taste as evaluated in pressure cooked meat by a semitrained panel on a 7 point Hedonic scale. 6. Except for duodenal and jejunal inflammation in chicks on both reference and test diets, all the vital organs were normal, ruling out any adverse affects caused by residual neem bitters. 7. Comparable performance and cost of chicks fed on the reference and L-ANKC 2 diets, warrants the utilisation of hitherto wasted protein-rich NKC after alkali treatment in broiler chick diets to spare peanut meal for human consumption in developing countries.

Alanine Transaminase↗
PubMed2006

Effect of alkali metal cation on the anaerobic hydrolysis and acidogenesis of vegetable waste.

Five batch testing scenarios were designed to evaluate the effects of alkali metal cations on anaerobic hydrolysis and acidogenesis. These scenarios were A (c=0 g l(-1)), B (cNa+=25 g l(-1)), C (cNa+=50 g l(-1)), D (cK+=25 g l(-1)), and E (cK+=50 g l(-1), pH 7.0). A solution pH of 7.0 or above favored protein hydrolysis, higher proteinase activity and higher ammonia production. However, such a pH suppressed carbohydrate hydrolysis, as indicated by low alpha-amylase activity. Cation interference at pH 5.0-6.0 seemed not to affect carbohydrate hydrolysis, as showed by the unimpaired alpha-amylase activity at 50 g l(-1) K+. Acidogenesis was more sensitive to alkali metal cations, so acid production and the drop in pH were lowest in a 25-50 g l(-1) Na+, acidic environment (pH 4.0-6.0). It was insensitive to cations when the pH was maintained at 7.0-8.0. When the pH was uncontrolled and decreased freely to acidic values, 25 g l(-1) of cation inhibited the action of the microbes, which rapidly acclimated, as presented by the slow transformation of soluble polymers to soluble metabolites. However, acidogenetic microbes could not easily recover from inhibition by 50 g l(-1) of cation. When the pH was maintained at over 7.0, the microbes were not inhibited by cation (50 g l(-1)) as indicated by the more active acidogenesis. The metabolic pathways to lactate, acetate and alcohols were not fully coupled.

Bacteria, Anaerobic↗
PubMed1998

Corrosion injury of the upper gastrointestinal tract after swallowing strong alkali.

OBJECTIVE: To review our experience of 9 patients who had attempted suicide by swallowing alkaline substances. DESIGN: Retrospective study. SETTING: Two university hospitals, Finland. PATIENTS: During the years 1987-1996. 9 patients who had swallowed more than 100 ml of strong alkali. RESULTS: 2 patients with oesophagorespiratory fistulas of the four with third degree injuries died in hospital, the first died of overwhelming sepsis and the second of multiple organ failure. The other two survived emergency staged resection and subsequent reconstruction. Delay between swallowing the alkali and the initial operation, and development of oesophagorespiratory fistulas were the most important predictors of death. Four patients with second degree injuries underwent oesophageal resection and reconstruction after they had developed oesophageal strictures. Two of these six survivors developed anastomotic strictures after reconstruction, both of which necessitated repeated oesophageal dilatations. One patient with a first degree injury was treated conservatively. CONCLUSIONS: An early and aggressive approach to severe third degree corrosive injuries of the upper gastrointestinal tract is needed to resect all necrotic tissue and to make it possible to do a successful reconstruction later. The development of oesophagorespiratory fistulas requires immediate attention, whereas first and second degree injuries can be treated after the patient has been stabilized.

Adolescent↗
PubMed1997

Effect of alkali metal cations on slow inactivation of cardiac Na+ channels.

Human heart Na+ channels were expressed transiently in both mammalian cells and Xenopus oocytes, and Na+ currents measured using 150 mM intracellular Na+. The kinetics of decaying outward Na+ current in response to 1-s depolarizations in the F1485Q mutant depends on the predominant cation in the extracellular solution, suggesting an effect on slow inactivation. The decay rate is lower for the alkali metal cations Li+, Na+, K+, Rb+, and Cs+ than for the organic cations Tris, tetramethylammonium, N-methylglucamine, and choline. In whole cell recordings, raising [Na+]zero from 10 to 150 mM increases the rate of recovery from slow inactivation at -140 mV, decreases the rate of slow inactivation at relatively depolarized voltages, and shifts steady-state slow inactivation in a depolarized direction. Single channel recordings of F1485Q show a decrease in the number of blank (i.e., null) records when [Na+]0 is increased. Significant clustering of blank records when depolarizing at a frequency of 0.5 Hz suggests that periods of inactivity represent the sojourn of a channel in a slow-inactivated state. Examination of the single channel kinetics at +60 mV during 90-ms depolarizations shows that neither open time, closed time, nor first latency is significantly affected by [Na+]0. However raising [Na+]0 decreases the duration of the last closed interval terminated by the end of the depolarization, leading to an increased number of openings at the depolarized voltage. Analysis of single channel data indicates that at a depolarized voltage a single rate constant for entry into a slow-inactivated state is reduced in high [Na+]0, suggesting that the binding of an alkali metal cation, perhaps in the ion-conducting pore, inhibits the closing of the slow inactivation gate.

Alkalies↗
PubMed1961

Graded and all-or-none electrogenesis in arthropod muscle. II. The effects of alkali-earth and onium ions on lobster muscle fibers.

Conversion of graded responsiveness of lobster muscle fibers to all-or-none activity by alkali-earth and tetraethylammonium (TEA) ions appears to be due to a combination of effects. The membrane is hyperpolarized, its resistance is increased, and its sensitivity to external K(+) is diminished, all effects which indicate diminished K(+) conductance. While the spikes are prolonged, the conductance is higher throughout the response than it is in the resting membrane. Repetitive activity becomes prominent. These effects indicate maintained high conductance for an ion which causes depolarization. This is normally Na(+), since its presence in low concentrations potentiates the effects of Ba(++), but the alkali-earth ions and TEA can also carry inward charge. Ba(++), Sr(++), and TEA appear to be more effective than is Ca(++) in its normal role, which is probably to depress K(+) conductance and Na inactivation. Thus, conversion of graded to all-or-none responsiveness appears to occur because of the relative increase of depolarizing inward ion flux and decrease of repolarizing outward flux.

Alkalies↗
PubMed1964

DISCRIMINATION BETWEEN ALKALI METAL CATIONS BY YEAST. I. EFFECT OF PH ON UPTAKE.

Extracellular pH markedly influences the ability of yeast cells to discriminate between K(+) and Na(+), with K(+) favored to a greater degree at low pH. Studies of the kinetics of uptake of individual alkali metal cations by fermenting yeast indicate three zones relative to pH. Between pH 6 and 8, H(+) has no effect. Below pH 4, H(+) competitively inhibits the transport of each cation. Between pH 4 and 6, H(+) acts kinetically as a predominantly non-competitive inhibitor. Both effects can be reversed by increasing the concentrations of cations. However, the concentrations required to reverse the competitive effect are considerably lower than those required to reverse the apparently non-competitive effect. It is suggested that H(+) and the alkali metal cations can combine with two sites, a transport or carrier site, and a second, non-transporting site that influences the maximal rate of transport. Because the non-competitive inhibitory effect of H(+) is considerably greater on the other cations than on K(+), the discrimination in favor of K(+) is increased severalfold at low pH, beyond that predicted on the basis of the relative affinities for the transport site.

Biological Transport↗
PubMed1987

Intracellular acidification-induced alkali metal cation/H+ exchange in human neutrophils.

Pretreatment of isolated human neutrophils (resting pHi congruent to 7.25 at pHo 7.40) with 30 mM NH4Cl for 30 min leads to an intracellular acidification (pHi congruen to 6.60) when the NH4Cl prepulse is removed. Thereafter, in 140 mM Na+ medium, pHi recovers exponentially with time (initial rate, approximately 0.12 pH/min) to reach the normal resting pHi by approximately 20 min, a process that is accomplished mainly, if not exclusively, though an exchange of internal H+ for external Na+. This Na+/H+ countertransport is stimulated by external Na+ (Km congruent to 21 mM) and by external Li+ (Km congruent to 14 mM), though the maximal transport rate for Na+ is about twice that for Li+. Both Na+ and Li+ compete as substrates for the same translocation sites on the exchange carrier. Other alkali metal cations, such as K+, Rb+, or Cs+, do not promote pHi recovery, owing to an apparent lack of affinity for the carrier. The exchange system is unaffected by ouabain or furosemide, but can be competitively inhibited by the diuretic amiloride (Ki congruent to 8 microM). The influx of Na+ or Li+ is accompanied by an equivalent counter-reflux of H+, indicating a 1:1 stoichiometry for the exchange reaction, a finding consistent with the lack of voltage sensitivity (i.e., electroneutrality) of pHi recovery. These studies indicate that the predominant mechanism in human neutrophils for pHi regulation after intracellular acidification is an amiloride-sensitive alkali metal cation/H+ exchange that shares a number of important features with similar recovery processes in a variety of other mammalian cell types.

Cesium↗
PubMed2001

Detection of alkali metal ions in DNA crystals using state-of-the-art X-ray diffraction experiments.

The observation of light metal ions in nucleic acids crystals is generally a fortuitous event. Sodium ions in particular are notoriously difficult to detect because their X-ray scattering contributions are virtually identical to those of water and Na(+.)O distances are only slightly shorter than strong hydrogen bonds between well-ordered water molecules. We demonstrate here that replacement of Na(+) by K(+), Rb(+) or Cs(+) and precise measurements of anomalous differences in intensities provide a particularly sensitive method for detecting alkali metal ion-binding sites in nucleic acid crystals. Not only can alkali metal ions be readily located in such structures, but the presence of Rb(+) or Cs(+) also allows structure determination by the single wavelength anomalous diffraction technique. Besides allowing identification of high occupancy binding sites, the combination of high resolution and anomalous diffraction data established here can also pinpoint binding sites that feature only partial occupancy. Conversely, high resolution of the data alone does not necessarily allow differentiation between water and partially ordered metal ions, as demonstrated with the crystal structure of a DNA duplex determined to a resolution of 0.6 A.

Barium↗
PubMed1983

On the denaturation of porcine erythrocyte catalase with alkali, urea, and guanidine hydrochloride in relation to its subunit structure.

The dissociation of porcine erythrocyte catalase [EC 1.11.1.6] into subunits on denaturation with alkali, GuHCl and urea was investigated by following the changes in hydrodynamic properties, absorption and CD spectra in the Soret region and inactivation of the enzyme. It was found that dissociation proceeded in an "all or none" manner from the native tetramer (molecular weight, ca. 250,000) into identical 1/4-sized monomers (molecular weight, ca. 54,000 with alkali, 65,000 with urea and 71,000 with GuHCl) as estimated by ultracentrifugal analyses. On this dissociation, the sedimentation coefficient decreased from about 11S to 5.1 - 3.7S, and absorption spectra in the Soret region decreased to about 40% of the native level and showed a broad band around 365-375 nm and a shoulder around 415-420 nm; these changes were accompanied by complete loss of enzyme activity. The change in enzyme activity correlated well with that of absorption and CD spectra in the Soret region, depending on denaturation time, alkaline pH used and concentration of both denaturants. The reassociated catalase obtained by removing urea by dialysis was characterized by recovery of distinct CD bands in the Soret and near ultraviolet regions, although the partial refolding of alpha-helical conformation occurred without recovery of enzyme activity. These results indicate that the conformational changes and dissociation process of catalase into subunits can be monitored spectrophotometrically in relation to enzyme activity, and that subtle conformations near the heme groups and polypeptide backbone play an important role in maintaining full enzyme activity of the catalase molecule.

Alkalies↗
PubMed1987

Therapeutic use of contact lenses in alkali burns of the cornea.

Rabbit eyes submitted to alkali burns (in 1 N NaOH, 7 mm, for 2 min) were evaluated as to the effect of contact lenses on the corneal reepithelialization. Forty eyes were used, divided into two groups: 3 weeks and those observed for 5 weeks. In each group, 10 eyes received a contact lens while 10 served as controls. From the daily evaluation of the corneal surface as well as the microscopic examinations at the end of the two periods of observation, we concluded that hydrophilic contact lenses provide a beneficial effect on alkali burns of the cornea, reducing the incidence of epithelial defects to statistically significant levels.

Alkalies↗
PubMed1991

The combined effect of citrate/ascorbate treatment in alkali-injured rabbit eyes.

The incidence of ulceration and perforation in the cornea of alkali-injured eyes is significantly reduced by treatment with trisodium citrate or sodium ascorbate. Topical citrate reduces the inflammatory response in the cornea by inhibiting polymorphonuclear leukocytes. Topical ascorbate elevates the depressed level of this vitamin in the alkali-injured cornea, reversing a scorbutic condition. The purpose of the current study was to determine whether combined treatment with topical citrate and ascorbate has an additional therapeutic value when compared with citrate alone. Adsorbotear without EDTA was used as the vehicle for both medications. Rabbit eyes were injured with 1N NaOH for 35 s using a 12-mm well and were rinsed. Group I (47 eyes) received two drops of 10% citrate every hour on the hour and Adsorbotear on the half-hour for 14 h/day. Group II (48 eyes) received two drops of 10% citrate every hour on the hour and 10% ascorbate every hour on the half-hour for 14 h/day. The citrate/ascorbate group had significantly fewer ulcerations during the experiment than did the group receiving citrate alone (2 of 48 versus 10 of 47, 0.01 less than p less than 0.02). Both anterior ulcers in the citrate/ascorbate group and five ulcers in the citrate group healed to no ulcer by the end of the experiment (0 of 48 versus 5 of 47, 0.02 less than p less than 0.05). The average depth of ulceration was significantly less for the citrate/ascorbate group (p less than 0.001). No descemetoceles or perforations were observed in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalies↗
PubMed2003

Visual rehabilitation after severe alkali injury with piggyback hyper O2 contact lenses.

PURPOSE: To report successful visual rehabilitation following severe bilateral alkali injury using piggyback hyperoxygen-transmissible (hyper O2) contact lenses. METHODS: Case report and literature review. RESULTS: More than 15 years after a severe bilateral alkali injury, multiple surgical procedures including repeat bilateral penetrating keratoplasty, severe tear deficiency, and chronic ocular surface disruption, the patient achieved 20/30 best-corrected vision through the simultaneous use of a hyper O2 rigid gas permeable contact lens over a hyper O2 soft contact lens in his right eye. The patient has tolerated this piggyback combination without any adverse reactions or complications, and his corneal graft remains clear and healthy. CONCLUSION: Visual rehabilitation for conditions that compromise the ocular surface can be accomplished by utilizing newer soft and rigid contact lens materials that facilitate oxygen transmission, thereby promoting epithelial healing and improving safety in extended wear situations. These newer materials may potentially reduce complications previously associated with extended wear therapeutic lenses.

Adult↗
PubMed1982

Elevation of the blood lactate concentration by alkali therapy without requiring additional lactic acid accumulation: theoretical considerations.

A patient presented with lactic acidosis and severe acidemia; sodium bicarbonate was administered to titrate the very large hydrogen ion load. Coincident with this therapy, the blood lactate concentration rose from 21 to 27 mmole/L. In order to evaluate whether this rise in lactate could have occurred without requiring additional net lactic acid production, the effect of the hydrogen ion concentration on lactate distribution was evaluated. Data obtained from animal studies support the established hypothesis that lactate is distributed like other weak organic acids at steady-state; hence, alkalemia should favor a shift of lactate from the intracellular fluid (ICF) to the extracellular fluid (ECF). The authors calculated that the blood lactate concentration could rise by 50% without requiring net lactic acid accumulation when the severe acidemia was corrected by alkali therapy. Thus, an increase in lactate concentration of the magnitude observed during alkali therapy need not indicate a worsening of the metabolic picture in lactic acidosis.

Alkalies↗
PubMed1979

Recommendations for fetal haemoglobin reference preparations and fetal haemogloblin determination by the alkali denaturation method.

Lyophilized haemoglobin mixtures containing HbF and HbA were investigated as reference preparations in an interlaboratory collaborative study. Haemiglobincyanide mixtures in Drabkin's solution with 450-550 mg Hb/dl and 0.2-60% HbF were divided into samples of 10 ml, lyophilized in plastic containers and stored without vacuum at -20 degrees C. After dissolution in 10 ml distilled water no change in spectral and electrophoretic properties or turbidity was observed; stable values for the total Hb concentration and HbF content were obtained over a period of over 2 years. These HbF standards can be prepared in reference laboratories and are recommended for quality control in HbF determination by alkali denaturation. For fetal haemoglobin determination the alkali denaturation technique of Berke, Marti and Schlicht is recommended for quantitation of HbF concentrations, at least between 2 and 40%. For values below 2% radioimmunoassay and for concentrations above 40% chromatographic procedures are more accurate. However, these methods will not be applicable in smaller haematological laboratories and in developing countries.

Alkalies↗
PubMed1989

Singlet oxygen induces frank strand breaks as well as alkali- and piperidine-labile sites in supercoiled plasmid DNA.

A covalently closed, circular, supercoiled plasmid was exposed to singlet oxygen by a separated-surface sensitizer. For each exposure, the quantity of single oxygen entering the DNA target solution was estimated by its oxidation of histidine. After singlet oxygen exposure, some DNA samples were treated to disclose occult lesions. Agarose gel electrophoresis was then used to resolve the unrelaxed supercoils from the relaxed circular and linear species, and all bands were quantitated fluorometrically. Exposure of supercoiled plasmid DNA to singlet oxygen induced frank DNA strand breaks, alkali-labile sites (pH 12.5, 90 degrees C, 30 min), and piperidine-labile sites (0.4 M, 60 degrees C, 30 min), all in a dose-dependent manner. Yields of alkali-labile and piperidine-labile sites ranged from one to four times the frank strand break yield. Replacement of buffered H2O by buffered D2O as the DNA solvent for singlet oxygen exposures increased DNA lesion yields by a factor of 2.6 (averaged over lesion classes). Our data for the detection of frank strand breaks is at variance with published results from studies in which singlet oxygen was derived from a thermolabile endoperoxide dissolved in the DNA solution.

Alkalies↗
PubMed1982

The use of contact lenses in environments with organic solvents, acids or alkalies.

The advantages and disadvantages of using soft contact lenses in environments with fumes from solvents or splashes of strong acids and alkalies were studied experimentally. Uptake of trichloroethylene and xylene by lens materials was up to 90 times that by physiologic saline, used to simulate tear fluid. However, when exposed lenses were soaked for 10 and 60 min in a very small volume of saline the concentration of solvents in that saline was only up to 23% and 11%, respectively, of that in directly exposed saline. Solvents were released mainly to the air. Thus, contact lenses would lead to a prolonged exposure but to a rather low concentration as compared to direct exposure. Other solvents may behave differently. Contact lenses did not protect the cornea against strong alkalies but did not seem to worsen the condition either. However, in the thicknesses used they provided a significant although incomplete protection against strong acids.

Acids↗
PubMed1993

Dialkylglycine decarboxylase structure: bifunctional active site and alkali metal sites.

The structure of the bifunctional, pyridoxal phosphate-dependent enzyme dialkylglycine decarboxylase was determined to 2.1-angstrom resolution. Model building suggests that a single cleavage site catalyzes both decarboxylation and transamination by maximizing stereoelectronic advantages and providing electrostatic and general base catalysis. The enzyme contains two binding sites for alkali metal ions. One is located near the active site and accounts for the dependence of activity on potassium ions. The other is located at the carboxyl terminus of an alpha helix. These sites help show how proteins can specifically bind alkali metals and how these ions can exert functional effects.

Amination↗
PubMed1969

Alteration of physical, chemical, and biological properties of endotoxin by treatment with mild alkali.

Treatment with alkali is one of several methods for removing fatty acids from bacterial endotoxins and, in the process, detoxifying the material. Saponification of fatty acid esters is the major detectable chemical change produced by alkali; however, kinetic studies of mild alkaline hydrolysis of endotoxin failed to correlate rates of detoxification with rates of loss of ketodeoxyoctonates, heptose, O-acetyl groups, or fatty acid esters. The alterations occurring during the critical stages of hydrolysis apparently changed the essential chemical conformation of endotoxic particles before cleavage of a significant amount of material took place. The rates of both saponification and detoxification were markedly increased by carrying out the reaction in media of ethyl alcohol or dimethylsulfoxide instead of water.

Alkalies↗