Phosphorus availability. 1. The effect of chick age and vitamin D metabolites on the availability of phosphorus in defluorinated phosphate.
Explore the source record for details and available documents.
Age Factors↗
SEARCH · PubMed Health
Results for “availability”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Editorial: Definition of the concepts availments and availability].
Explore the source record for details and available documents.
Absorption↗
Effects of the intracoronary and intraventricular injections of a commonly available vs. a newly available contrast medium.
Two contrast media (Renografin 76 and Isopaque 370) were used in a double-blind study for coronary angiography and left ventriculography. Fifty-eight patients with presumed coronary artery disease were studied. The effects of the contrast media upon the myocardium and upon ventricular function of patients with and without coronary artery disease were assessed. Pre and post angiography myocardial enzymes were obtained. Cardiac output was determined before and after the angiograms. Hemodynamic and electrocardiographic changes were continuously monitored during the procedure. The study showed that both contrast media produced similar changes; however, the "maximum" decrease in T wave amplitude was more marked in the normal group when Renografin 76 (as compared with Isopaque 370) was injected (p = 0.05) on the right. Renografin 76 injection into the left coronary artery produced a higher median T wave amplitude in lead II relative to Isopaque 370 only in the abnormal group (p = 0.01). The heart rate dropped more severely in the normal patients when the left coronary artery was injected with Renografin 76 than with Isopaque 370 (p = 0.05).
Angiocardiography↗
Light-induced de-epoxidation of violaxanthin in lettuce chloroplasts. IV. The effects of electron-transport conditions on violaxanthin availability.
1. In isolated chloroplasts of Lactuca sativa var. Manoa, the size of the violaxanthin fraction which is available for de-epoxidation is not directly dependent on electron transport but rather related to the reduced level of some electron carrier between the photosystems. This is concluded from the effects of various electron-transport conditions on violaxanthin availability: Under conditions of electron transport through both photosystems, availability was saturated at a lower electron-transport rate with actinic light at 670 than at 700 nm. Under conditions of electron transport through Photosystem I, availability was smaller for linear electron flow from reduced N-methylphenazonium methosulfate via methylviologen to oxygen than from cyclic electron flow mediated by either N-methylphenazonium methosulfate or 2,6-dichlorophenolindophenol; in addition for linear flow from reduced N-methyphenazonium methosulfate via methylviologen to oxygen, availability increased with decreasing light intensity. 2. The postulated carrier whose reduced level is related to availability seems to be some carrier between plastoquinone and the primary acceptor of Photosystem II or plastoquinone itself. This conclusion follows from the fact that availability increased with increasing light intensity under conditions of electron flow through both photosystems and that 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (greater than or equal to 1 mu M) had no effect on availability, whereas low levels of 3, 3-(3',4'-dichlorophenyl)-1,1-dimethylurea resulted in decreased availability (50 percent decrease at 1 mu M). Furthermore, availability in 3,3-(3',4'-dichlorophenyl)-1,1-dimethylurea-poisoned chloroplasts was fully restored by 2-methyl-1,4-naphtoquinone (menadione) which mediates cyclic electron flow through plastoquinone. 3. Violaxanthin availability was zero in the dark and increased in the light to maximum of 67 percent of the total violazanthin in chloroplasts. It is proposed that this variable violaxanthin availability reflects conformational changes on the internal surface of the thylakoid membrane which result in variable exposure of violaxanthin to the de-epoxidase. The fact that not all of the violaxanthin was available for de-epoxidation may indicate a heterogenous distribution of violaxanthin in the membrane.
Aerobiosis↗
Determining optimal heat treatment of soybeans by measuring available lysine chemically and biologically with rats to maximize protein utilization by ruminants.
Soybeans were heated in a forced air oven at 120 and 130 degrees C for 60 and 180 min, and at 140, 150 and 160 degrees C for 10, 30, 60, 90 and 120 min. Two types of measurements were used to determine optimal heat treatment of soybeans to maximize protein utilization by ruminants. One was to estimate the rate and extent of protein degradation in the rumen using an in vitro ruminal system. The second was to determine the nutritional availability of lysine. Methods used to determine available lysine were an indirect fluorodinitro-benzene chemical method and a rat growth assay. The product of undegraded intake protein and available lysine content was used to estimate the amount of lysine that would escape ruminal degradation and be available for intestinal absorption. As heat input increased, ruminal undegraded intake protein increased, and protein degradation rates and total and available lysine decreased. As temperature increased, the time required to maximize post-ruminal available lysine decreased. The optimal heat treatment for soybeans heated in a forced air oven was: 140 degrees C for 120 min or greater, 150 degrees C for 60 min or 160 degrees C for 30 min. A loss of 15-22% of chemically determined available lysine was necessary to achieve the heat treatment that resulted in maximal post-ruminal available lysine.
Animals↗
Assessment of the nutritional quality of proteins: the use of "ileal" digestibilities of amino acids as measures of their availabilities.
1. A comparative study was made of two biological techniques for assessing protein quality in wheat and barley, and in a soya-bean-protein isolate both as received, and after being heat damaged by autoclaving. Amino acid digestibility was determined by the "ileal" analysis technique while amino acid availability was measured in growth assays. Some chemical and microbiological tests were also done. 2. Heat treatment of the soya-bean-protein isolate caused little change in amino acid composition but the digestibility of all amino acids and the availability of lysine and methionine were severely reduced, lysine being most affected. The reduced availability of lsyine was not entirely attributable to impaired digestibility. 3. The amino acids in wheat and barley were highly digestible. The availability of methionine and lysine in barley and of methionine in wheat was high, whereas the availability of lysine in wheat was apparently much lower. 4. The results showed that for methionine, digestibility values are a fair measure of the availability. In heat-damaged soya-bean-protein isolate however, digestibility of lysine over-estimated the availability, indicating that amino acid digestibility may sometimes provide a misleading indication of nutritional value.
Amino Acids↗
A method for estimating the available energy of incompletely digested carbohydrates in rats.
We developed a method to estimate the available energy from carbohydrates that are unavailable or partially unavailable through direct digestion and absorption. Radiolabeled bacterial and plant cellulose and polydextrose were administered orally to germfree and conventional rats. Label in breath, feces, intestinal contents and carcass were determined with excellent total recovery of the administered label. Comparison of these measurements in germfree and conventional rats was used to calculate the energy directly available by digestion and that available only after fermentation. Although the method overestimates available energy because of the more efficient digestive metabolism of the germfree rat, it provides a reliable, maximum energy value based upon fewer assumptions than previous methods. In conventional rats, 65% of the administered cellulose and 54% of the administered polydextrose were recovered in feces. In conventional rats, appreciable amounts of cellulose were fermented and an available energy value of 3.5 kJ/g was calculated. Calculation of the total availability of polydextrose, taking into account the direct absorption of small amounts of monomers present and the efficiency of fermentation, indicates an available energy value of 4.7 kJ/g.
Administration, Oral↗
Context availability and the recall of abstract and concrete words.
Predictions of an automatic-imagery, strategic-imagery, and context-availability hypothesis of concreteness effects in free recall were examined. In each experiment, recall of abstract and concrete words controlled for rated context availability was compared with the typical situation in which context availability is confounded with imageability. In Experiment 1, a directed intentional-recall task produced concreteness effects in recall. Experiment 2 compared concreteness effects in recall following three orienting tasks: imagery rating, context-availability rating, and a directed intentional-memory task. Concreteness effects in the context-availability-controlled condition were found following the imagery-rating and the directed intentional-memory tasks, but not after the context-availability-rating task. In Experiment 3, subjects reported the strategies that they used to encode the list. Subjects reporting an imagery strategy showed concreteness effects for words controlled for rated context availability, but those not reporting it did not. These results support a strategic-imagery view of concreteness effects in free recall.
Humans↗
Synergic impact mechanisms of cover crop residue on Cd and As availability and native organic carbon mineralization in Cd and As co-contaminated paddy soil.
The synergic impacts of cover crop residue on heavy metal and metalloid availability and soil organic carbon (SOC) mineralization in contaminated paddy soil and the underlying microbial mechanism remain unclear. This study investigated the availability of cadmium (Cd) and arsenic (As) and mineralization of native SOC in paddy soil treated with 0, 0.4 %, 0.8 % and 1.2 % of δ13C-labeled cover crop residue (Astragalus sinicus L.) via 90-day incubation experiments, the related functional genes and functional microbial communities were analyzed using metagenomic binning assembly. Cover crop residue with addition rate from 0.4 % to 1.2 % significantly decreased available Cd by 56 %-85 % but increased available As by 39 %-66 % compared to the control treatment. Cover crop residue resulted in a positive priming effect on native SOC mineralization but benefited SOC sequestration. Cover crop residue increased the abundance of genes encoding iron reductase (mtrABC, pilA, omcB), sulfate reductase (sir, fpr), As(V) reductase (ArsC), organic carbon hydrolases, methanogenesis, and methylotrophy. Genomes associated with Chloroflexota and Bacteroidota encoded all these key pathways, and their abundance increased with cover crop residue application. Cover crop residue decreased soil Eh, dissolved crystalline iron oxides, enriched specific microorganisms, including Chloroflexota and Bacteroidota, and then synergistically promoted the decrease in Cd availability and the increase in As availability and native SOC mineralization in the examined paddy soil. These findings provided practical and feasible guidance for achieving both safe production and carbon sequestration in contaminated paddy fields, highlighting the requirement to cautious utilization of cover crop residue in As-contaminated paddy fileds.
Soil Pollutants↗
Availability of lysine in protein concentrates as determined by the slope-ratio assay with growing pigs and rats and by chemical techniques.
1. A slope-ratio assay was developed with growing pigs to determine the availability of lysine in five protein concentrates. The basal diet contained 5.2 g lysine/kg and six levels of lysine, in 500 mg/kg increments, were used to determine the pig's response to standard lysine. The protein concentrates were incorporated into the basal diet to provide five levels of total lysine, again in 500 mg/kg increments, at the expense of wheat starch. A daily feeding scale based on live weight was used to ensure similar nutrient intakes. Pigs were fed at three-hourly intervals to ensure the utilization of free amino acids in the diets. Four pigs were allotted to each dose level and response was assessed over the 20--45 kg growth phase. 2. Potency estimates for available lysine in the five protein concentrates varied, depending on whether live-weight gain or carcass gain was used as the criterion of response. Carcass gain was considered more appropriate as it was not influenced by variation in gut fill. Availability of lysine in the five proteins, using carcass gain/d were (proportion of total) cottonseed meal 0.39,fish meal 0.89, meat-and-bone meal 0.50, skim-milk powder 0.88 and soya-bean meal 0.87. 3. Rat slope-ratio assay results for available lysine in the five protein concentrates were in general agreement with those from the pigs. In contrast, the differences in available lysine were not detected by the chemical Silcock available-lysine test (Roach et al. 1967) nor by the direct fluorodinitrobenzene procedure (Carpenter, 1960).
Animals↗
Myocardial oxygen availability and cardiac failure in hemorrhagic shock.
The relationships between left ventricular function and myocardial O2 availability and metabolism were studied in cats with hemorrhagic shock (AP=30 mm. Hg) with the use of a right heart bypass preparation. Aortic flow and heart rate were held constant. Oxygen-carrying capacity was reduced by diluting donor blood with an equal volume of 5 per cent glucose in saline. Oxygen availability was estimated as the product of arterial O2 content and coronary blood flow. All shock animals showed a progressive metabolic acidemia with time, and a fall in coronary flow concomitantly. Four control animals (AP=75 mm. Hg) as well as two shock animals with high arterial oxygen content and hematocrit showed no significant changes in myocardial O2 metabolism or performance over a period of 90 minutes. Nine shock animals with reduced hematocrit demonstrated a progressive reduction in ventricular function, myocardial O2 metabolism, and O2 availability. As O2 availability fell below 10 ml. per minute per 100 Gm. of heart weight, cardiac failure uniformly appeared and was accompanied by a reduction in O2 extraction and consumption. The correlation between left ventricular dP/dt max and O2 availability was highly significant (r = 0.75, p less than 0.01) in shock animals but not in controls. Thus a close relationship between myocardial O2 metabolism and function during the course of hemorrhagic shock has been demonstrated. Reduced myocardial O2 availability is directly linked with the appearance of cardiac failure.
Animals↗
Estimation of available dietary iron.
Dietary iron requirements are dependent on the amount and availability of food iron ingested. On the basis of recent studies of food iron absorption employing extrinsic tag techniques, the availability of heme iron has been defined and estimates of the availability of nonheme iron based on the amounts of enhancing substances appear possible. A model has been developed whereby the availability of iron in a given meal may be estimated. Calculations are made on a meal basis of 1) the amount of heme iron and its availability, and 2) the amount of nonheme iron and its availability as influenced by the meal's content of enhancing factors. Examples of these calculations are provided.
Absorption↗
Alterations in hepatic chromatin template availability during infection.
Hepatic chromatin was isolated from rats at various times after inoculation with either live or heat-killed bacteria. The chromatin was assayed under conditions that allow determination of the DNA template available to support in vitro transcription. Both a fulminant Diplococcus pneumoniae and a milder Salmonella typhimurium infection produced time-related increases in hepatic chromatin template availability when compared to chromatin isolated from rats inoculated with heat-killed bacteria. Both timing and magnitude of increased template availability correlated with the severity of the infection. The earliest change observed was a 50 percent rise in availability noted 4 h after inoculation with D. pneumoniae. This preceded the onset of fever, as well as other known heaptic consequences of systemic infection. After 24 h of infection the maximum rise of 90 percent occurred. Similar changes developed during S. typhimurium infection, but were slower in onset and smaller in magnitude. Adrenalectomy prior to infection enhanced the severity of the disease but markedly blunted the increase in template availability. The data are consistent with the hypothesis that systemic infection regulates the hepatic metabolic response to infection through transcriptional control and that a permissive or stimulatory action of glucocorticoids is involved in the increases in template availability effected.
Adrenalectomy↗
Effect of processing on availability of essential amino acids in rice flour and cooked rice.
The availability of nitrogen, lysine and nine essential amino acids was determined in rice flour and cooked rice. Lysine availability was determined by the growth response method using regression analysis of body weight gain or moisture gain against lysine consumed from rice flour and cooked rice. The results show a good correlation between lysine consumed and weight gain or moisture gain (r = 0.86 + 0.8) for rats fed cooked rice and fair correlation for those fed rice flour. The results of lysine availability show that cooking increases availability by both ways of calculation. The availability of nitrogen and of essential amino acids was also determined by the balance trial method with rats. Results of balance trial show that cooking has no significant effect on essential amino acids availability. Data for weight gain, food efficiency and PER were significantly decreased by cooking.
Amino Acids, Essential↗
[Measure of available and blocked lysine in industrial milks].
The classical methods to measure lysine availability give rise to some difficulties in milks due to the presence of deoxyketose-lysine (DOKL). Six methods, one of which measuring the blocked lysine, are studied. Amino acid chromatography gives a too high value of lysine when it is blocked as DOKL, the latter regenerating lysine during acid hydrolysis. The determined lysine does not correspond to the available one. Fluro-dinitro-benzene is not fully specific for free epsilon-NH2 of lysine and the reducing sugars present interfere during the reaction in converting "nitro" into "amino" groups. Guanidization is a specific reaction between the epsilon-NH2 of lysine and O-methyl-isourea with formation of homoarginine. The homarginine, calculated as lysine corresponds to the available lysine. Reduction with sodium borhydride converts the DOKL to a stable compound which, during acid hydrolysis, does not regenerate lysine and does not form furosine. The recovered lysine corresponds to the available one. Our "in vitro" digestion method with simultaneous dialysis enables the determination of available lysine, as the proteolytic enzymes used do not split up the DOKL binding. The liberated lysine corresponds to the available one. The blocked lysine is measured from furosine after acid hydrolysis. A formula, which makes up the level of furosine formation and for lysine regeneration from DOKL, is established.
Amino Acids↗
[Determination of metabolic availability of zinc and estimation of zinc requirements through changes in the activity of metallo-zinc enzymes].
Data on the zinc requirements of animals vary widely with the type of diet or kind of zinc compound considered, as they are dependent on the kind of definition and estimation of mineral requirements used which, in turn, are based on the analytical content of the mineral in the diet. Actually, requirements for a particular trace element are the same for any diet provided differences in the rate of absorption and metabolic availability of the element are taken into consideration. A suggestion is made in the present paper to utilize changes in the activity of different metallo-zinc enzymes as a method for determining the degree of metabolic availability of zinc. Within the framework of a repletion trial young male rats were fed a semisynthetic casein diet containing 1.2 ppm of zinc for a 14-day period of zinc depletion followed by a 15-day repletion period during which the rats received a diet containing 4.5 ppm or 12 ppm of zinc. In this trial the pattern of activity of the alkaline phosphatase in serum and in the femoral bones was studied and the level of pancreatic carboxypeptidase A and B was estimated. The data thus obtained were compared with those of pair-fed control animals and control animals fed a libitum. (96 ppm of dietary zinc). The results of the present trial show the metabolic availability of zinc can be determined by measuring the level of activity of these metallo-zinc enzymes. A suitable model was established. Moreover, attempts have been made to show in which way the zinc demands of growing, full-grown, pregnant and lactating animals may be estimated by measuring changes in the degree of activity of these metallo-zinc enzymes. A definition is, in this case, given by that amount of zinc which allows for an optimum activity of the different metallo-zinc enzymes. Such data are applicable only to a particular diet or are valid only for a particular zinc compound. Principally, it is much better to relate the Zn requirements of the animal to the level of absorbable and metabolically available zinc. The present model has been suggested to provide a possibility for measuring the metabolic availability of zinc in the body.
Alkaline Phosphatase↗
A rat bioassay for measuring the comparative availability of carbohydrates and its application to legume foods, pure carbohydrates and polyols.
An assay was developed to evaluate the bioavailability of dietary carbohydrate by slope-ratio analysis of weight gain and plasma ketones of rats fed a carbohydrate-free diet supplemented with glucose as a standard and selected food items, pure carbohydrates and polyols. The diet was based on 35% food grade oleic acid, 12% casein protein supplemented with methionine (0.3%) and arginine (0.2%), 7.5% soybean oil, 37% cellulose, minerals and vitamins. Glucose, as the reference standard, or test materials were incorporated in the diet by replacing equi-energetic amounts of oleic acid and adjusting cellulose to equalize total weight. Optimal levels of protein (casein) and triglyceride (soybean oil) in the basal diet were defined as those levels above which additional protein or fat would serve only to provide endogenous glucose from their glucogenic amino acids and glycerol constituents. A standard dose-response curve was obtained by feeding diets containing 0%, 1% and 2% glucose. Similar dose response curves were obtained by feeding test materials. Under these experimental conditions, additional glucose or additional protein were growth stimulating and casein had approximately 50% of the value of an equal weight of glucose, which was consistent with its content of glucogenic amino acids. The specific carbohydrate value of a food was estimated in the assay by subtracting the calculated glucogenic value of its digestible protein from the total response. The apparent availability of the carbohydrates (i.e., nitrogen-free extract) in soybean meal, lima bean (Phaseolus lumatus), and chick pea (Cicer arietinum) were 35, 70, and 80%, respectively, as available as glucose. Galactose, a 1:1 mixture of galactose + glucose, fractose and starch were as available as glucose. Lactose, ribose, sorbitol, and xylitol were 50 to 65% as available as glucose while mannitol and inulin were not available to a significant extent. Possible metabolic bases for these differences are discussed.
Amino Acids↗
Fluoride availability in human saliva after dentifrice use: correlation with anticaries effects in rats.
Studies were conducted to determine fluoride availability in saliva after dentifrice use and to relate this parameter to cariostatic efficacy in rat caries experiments. Three dentifrices--two commercial formulations (Colgate Winterfresh Gel and Crest Dentifrice with Na-Sr-polyacrylate) and an Experimental dentifrice--were compared with respect to salivary fluoride availability. All of the dentifrices tested contained 1100 ppm F as sodium fluoride. It was observed that the Experimental dentifrice and Crest dentifrice with Sr-polyacrylate exhibited low salivary fluoride availability relative to the Colgate Winterfresh Gel. Salivary fluoride availability was assessed by means of two parameters: (a) the fluoride concentration in the dentifrice saliva slurry expectorated after brushing, and (b) the area under the curve of salivary F concentration vs. time for up to two hours after dentifrice use. In two rat caries experiments, it was observed that both the Experimental dentifrice and the Sr-polyacrylate dentifrice provided less cariostatic efficacy than the clinically validated Positive Control (Colgate Winterfesh Gel). Analysis of these data provides further evidence in support of the concept that fluoride availability in saliva following dentifrice use is an important parameter related to anticaries efficacy.
Acrylic Resins↗