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PubMed1998

[Availability, use and cost of antidotes in Catalonia].

BACKGROUND: To know the availability of antidotes in hospital and extra-hospital emergency services in Catalonia (Spain), their real use, and the cost. PATIENTS AND METHODS: Availability was studied by means of a transversal questionnaire carried out in 24 hospitals and 3 extra-hospital emergency services in Catalonia; the real use of antidotes was investigated using a prospective study carried out for one year in the same 24 hospitals, and the cost was determined using the data obtained over 12 months in one large hospital. RESULTS: Average availability was 35 antidotes in hospital and 13 in extra-hospital emergency services. In no service did the availability coincide exactly with that of another service, nor with the recommendations made by international institutions (World Health Organization and International Programme for Chemical Safety) or the Government of Catalonia. The low incidence of availability of antidotes to cyanide was notable. Antidotes were used in 12.9% of acute intoxications. In 167 cases treated with these drugs, only 9 different antidotes were used. The consumption of these antidotes represents 0.1% of the budget of a pharmacy service in one large hospital. CONCLUSIONS: The availability of antidotes in Catalonia is heterogeneous and some services lack antidotes whose use is considered essential. Antidotes are scarcely used in acute intoxications and their economic cost is low.

Antidotes↗

PubMed2000

Systemic availability and lymphatic transport of human growth hormone administered by subcutaneous injection.

Degradation of human growth hormone (hGH) at the injection site has previously been implicated as the basis for its reduced systemic availability following subcutaneous (SC) administration. The goal of these studies was to develop an animal model which would allow mass balance calculations to (i) quantify the loss at the injection site and (ii) determine the role of the lymphatics in the transport of subcutaneously-administered hGH. The animal model utilized a sheep and enabled simultaneous sampling of blood and collection of either peripheral lymph (via the efferent duct of the popliteal lymph node draining the injection site) or central lymph (via the thoracic lymph duct). In non-lymph cannulated sheep, the systemic availability of hGH following SC dosing was 58.4 +/- 9.1% (mean +/- SEM) relative to an intravenous (IV) control. The availability of hGH decreased to approximately 30-40% when either peripheral or central lymph was collected indicating that a proportion of the dose was transported via the lymph. The fraction of the administered dose collected in peripheral lymph was 61.7 +/- 8.5% (mean +/- SEM), whereas only 8.6 +/- 1.3% was collected in central lymph. These results suggested that loss of hGH within the lymphatics contributed significantly to its reduced systemic availability following SC administration. The total recovery (sum of the systemic availability and the cumulative amount recovered in lymph) of hGH was approximately 93% of the dose in the peripherally-cannulated group indicating that loss at the injection site was minimal.

Animals↗

PubMed1989

Effect of addition of bovine milk and vegetable milks on the in vitro availability of iron from cereal meals.

Studies were carried out on the in vitro availability of iron from a standard cereal meal with and without the addition of bovine milk (BM), groundnut milk (GM) and soybean milk (SM). Further, availability of iron from these milks per se was also investigated. Estimation of the total iron content from BM, GM, and SM revealed that it was highest in case of SM followed by GM and BM. This trend was reversed for percent available iron which was highest for BM followed by GM and SM. The in vitro availability of iron from the cereal meal was low (3.7%). Addition of BM and GM enhanced the availability of iron from the standard meal whereas SM had no particular enhancing quality. The practical implications of the findings for iron nutrition in humans are discussed.

Animals↗

PubMed2001

Estimation of available energy of dietary fibres by indirect calorimetry in rats.

BACKGROUND: Knowledge of energetic availability of dietary fibres is important for human nutrition. But up to now results are often different and depend on the methods used. Estimation of metabolisable energy of dietary fibres (mainly by balance technique) is a time-consuming procedure and needs special technical effort. AIM OF THE STUDY: Validation of the experimental design for short-term studies by using indirect calorimetry with feeding below maintenance requirement to evaluate the energetic availability of dietary fibres and their influence on absorption velocity of carbohydrates (CHO). METHODS: Energy expenditure and CHO oxidation (including short-chain fatty acids as fermentation products) were estimated in Wistar rats over 23 h after being fed a basal diet for the first day (300 KJ/kg0.75, 20% protein, 3% fat, 77% CHO) followed by supplementation with either microcrystalline cellulose, the soluble rye fibre arabinoxylan, apple pectin, amylomaize starch (with 48% of resistant starch) or gelatinised wheat starch (200 KJ/kg0.75 each) as control for the following days. Energetic availability was determined by comparing the increase of CHO oxidation after addition of gelatinised wheat starch with that of the dietary fibres tested. RESULTS: In comparison to wheat starch (100%), the following energetic availability of the dietary fibres was found: microcrystalline cellulose 14%, arabinoxylan 33%, pectin 39%, amylomaize starch 62%. The time-course of CHO oxidation indicated that microcrystalline cellulose enhances, whereas the soluble rye fibre slows down the velocity of CHO absorption due to the different consistency of the intestinal contents modified by the kind and properties of the used dietary fibres. After intake of arabinoxylan or pectin, CHO oxidation remained at a higher level during the experimental period elucidating an increased activity of fermentation to short-chain fatty acids. CONCLUSIONS: Short-term experiments in rats using indirect calorimetry are a suitable method for comparative estimation of the energetic availability of dietary fibres. Results are partly in agreement with values estimated by long-term in vivo methods.

Animals↗

PubMed2000

Application of a dynamic in vitro gastrointestinal tract model to study the availability of food mutagens, using heterocyclic aromatic amines as model compounds.

The TNO gastro-Intestinal tract Model (TIM) is a dynamic computer-controlled in vitro system that mimics the human physiological conditions in the stomach and small intestine. In the current TIM physiological parameters such as pH, temperature, peristaltic movements, secretion of digestion enzymes, bile and pancreatic juices, and absorption of digested products-by removal through dialysis-was simulated. Heterocyclic aromatic amines (HAA; viz. IQ, MeIQ, MeIQx and PhIP) were used as model compounds for food mutagens, and the passage through TIM was investigated for each of these compounds separately. Subsequently, the influence of a matrix and different rates of passage on the availability for absorption and distribution were studied in experiments with prepared meat, supplemented with MeIQx. Samples taken at various time points from the jejunal and ileal dialysates and from the lumen at the end of the small intestine (ileal delivery) were tested for the presence of mutagenic activity in the Ames test with Salmonella typhimurium strain TA98 as indicator, in the presence of mammalian metabolic activation (rat S9 mix). The results show that, comparable with the human in vivo situation, all four HAA are quickly removed (approx. 50% in 2 hr; approx. 95% in 6 hr) and mainly recovered from the lumen into the jejunal and ileal dialysates (94% of recovery). Only 5+/-1.5% is recovered in the chyme at the end of the small intestine. When MeIQx was added to meat, its availability for absorption was slower, although the influence of the gastrointestinal passage time on the availability of MeIQx was more pronounced than this matrix effect. More MeIQx was found in the jejunal dialysate (23%; P<0.01) and less in the ileal delivery (8%; P<0.01) when simulating the gastrointestinal passage of solid meals was compared to simulating that of liquid meals. The present experiments demonstrate that TIM can be applied to study in vitro the availability of heterocyclic aromatic amines in the gastrointestinal tract. More generally, these studies indicate that TIM shows promise as a useful tool for various research purposes dealing with the availability for absorption of mutagenic as well as antimutagenic components in food.

Biological Availability↗

PubMed2005

Iron and zinc in vitro availability in pearl millet flours (Pennisetum glaucum) with varying phytate, tannin, and fiber contents.

Simulations of gastro-intestinal digestion, used to estimate in vitro iron and zinc availability, were performed on two kinds of samples: (i) samples with decreased phytate contents from whole pearl millet flour and (ii) nondephytinized or dephytinized samples from two pearl millet grain fractions, a decorticated fraction with low fiber and tannin contents and a bran fraction with high fiber and tannin contents. Iron and zinc in vitro availabilities of whole pearl millet flour were significantly improved by phytate degradation, even if the IP6 were not all degraded. Total dephytinization of decorticated fraction led to a marked increase in iron and zinc in vitro availabilities, but that of bran fraction had no effect on either iron or zinc in vitro availability. Even if phytates are involved in reducing in vitro iron and zinc availability in pearl millet flour, fibers and tannins play an important role by chelating a high proportion of iron and zinc in grain hulls.

6-Phytase↗

PubMed1987

An equation for the systemic availability of drugs undergoing simultaneous enterohepatic cycling, first-pass metabolism, and intestinal elimination.

A relationship between systemic availability and its determinants has been derived for a physiologically realistic model of drug disposition that includes enterohepatic cycling (EHC), gallbladder emptying (with an arbitrary time course), first-pass metabolism to noncycling metabolites, and fecal excretion. Systemic availability (F) has been shown to be determined by the fraction of the dose initially absorbed (f*a), the fraction of the drug excreted into the GI tract that is reabsorbed with each cycle (fa), the hepatic extraction ratio (E), and the fraction of extracted drug that is transported to the gallbladder for EHC (fg) according to the relationship F = f*a(1 - E)/(1 - fafgE) The implications of the above relationship are that (1) systemic availability is dependent on EHC, (2) values of F calculated to be greater than unity cannot be explained simply by the presence of EHC, (3) calculations of E based on the usual expression F = f*a(1 - E) are erroneous for drugs subject to EHC, and (4) a compound that has a high systemic availability and is subject to EHC is not necessarily inefficiently metabolized. The quantitative interrelationship of systemic availability and its determinants is illustrated using a contour plot. Slices through the surface are used to demonstrate that the presence of EHC changes the sensitivity of F to changes in E.

Animals↗

PubMed1986

Availability of lysine in meat meal, meat and bone meal and blood meal as determined by the slope-ratio assay with growing pigs, rats and chicks and by chemical techniques.

1. The availability of lysine in four meat meals (MMs), four meat and bone meals (MBMs) and two blood meals was determined using the slope-ratio assay with growing pigs, rats and chicks and with two chemical techniques. 2. The availability of lysine (proportion of total) in the eight MMs or MBMs ranged from 0.48 to 0.88 for pigs, from 0.49 to 0.88 for rats and from 0.68 to 0.88 for chicks. There was no apparent relation between the availability estimates for pigs, rats and chicks for the individual meals. 3. For the two blood meals, availability estimates were 1.03 and 1.13 for pigs, 0.81 and 0.80 for rats and 1.07 and 1.02 for chicks. 4. Values for the indirect and direct 1-fluoro-2,4-dinitrobenzene-'available'-lysine assays ranged from 0.77 to 0.88 and 0.78 to 0.93 respectively for the eight MMs and MBMs. There appeared to be no relation between these values and the pig estimates.

Animal Feed↗

PubMed1986

Determination of digestible and available amino acids in meat meal using conventional and caecectomized cockerels or chick growth assays.

1. The present study was designed to compare true digestible amino acid values for meat meal with available amino acid values. True digestible values were determined with a 48 h excreta collection assay using conventional (CONV) and caecectomized (CEC) cockerels. Available values for lysine, methionine and cystine were estimated by chick growth assays. 2. True digestibilities of all sixteen measured amino acids (expressed as a proportion of the total) were lower for CEC than for CONV cockerels, with the average difference being approximately 0.10. 3. Chick growth assays based on total weight gain indicated that the availabilities of amino acids expressed as a proportion of the total amino acids in meat meal were: 0.70 for lysine, 0.75 for methionine and 0.48 for cystine. Partitioning weight gains to reflect only growth attributable to supplemental crystalline amino acid or meat meal intake consistently yielded higher availability values than when total weight gains were used. 4. True digestibility values determined with CEC cockerels were in better agreement with chick available values than were true digestibility values determined with CONV cockerels. 5. The amounts of amino acids present in the caeca of meat meal-fed CONV cockerels at 48 h after feeding were small when compared with those levels voided in the excreta and those levels consumed in the feed. 6. Multiple regression analyses of excreta and caecal amino acid profiles at 12 and 48 h after feeding suggested that significant amounts of non-digested dietary amino acids flowed into the caeca and were subsequently metabolized by the caecal microflora.

Amino Acids↗

PubMed1975

[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↗

PubMed1981

Availability of vitamin B6 and pantothenate in an average American diet in man.

The availability of vitamin B6 and pantothenate in an average American diet was assessed healthy male volunteers. The subjects received two types of diets, both nutritionally equivalent to the average American diet: period 1 (35 days), semipurified formula diet (low in both vitamins) with daily supplements of 1.1 mg pyridoxine and 8.2 mg pantothenate; period 2 (35 days), natural food sources, providing 2.3 mg vitamin B6 and 11.5 mg pantothenate/day; period 3 (21 days), formula diet, providing 2.7 mg pyridoxine and 8.2 mg pantothenate/day. Daily protein intake was 96 g throughout the study. Vitamins in food and urine samples were determined microbiologically and plasma pyridoxal phosphate by a tyrosine apodecarboxylase radioassay method. Compared to the availability of the pure vitamins as 100%, the availability of vitamin B6 ranged from 61 to 81% with a mean of 71% using plasma pyridoxal phosphate data, and ranged from 73 to 92% with a mean of 79% according to urinary vitamin B6 data. Availability of pantothenate ranged from 40 to 61% with a mean of 50%, according to urinary pantothenate data. The average American diet used in our study contained 1.7 and 5.8 mg/day of available vitamin B6 and pantothenate, respectively.

Adult↗

PubMed1979

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↗

PubMed1981

Apparent and true availability of amino acids from common feed ingredients for channel catfish.

The apparent and true amino acid availability values for corn, wheat middlings, rice bran, rice mill feed, soybean meal, peanut meal, cottonseed meal, meat and bone meal, and two different samples of menhaden fish meal were determined in adult channel catfish. Although there was reasonable agreement between protein digestibility values and average amino acid availability values, individual amino acid availabilities were variable within and among the various feed ingredients tested. Therefore, we recommended that amino acid availability values should be used for more accurate catfish feed formulation. In addition, it appears that the use of true amino acid availability values should be used for feed ingredients of relatively low protein content.

Amino Acids↗

PubMed2004

Investigations on the availability of inorganic phosphate from different sources with growing White Pekin ducks.

Methodological aspects of determination of P availability in ducks were addressed in this study. Three balance experiments with quantitative excreta collection were performed with growing male White Pekin ducks that were 3 wk of age. When P from monobasic calcium phosphate (MCP) was added in graded levels below the requirement to a low-P basal diet, ducks responded nonlinearly in P accretion. With increases in dietary Ca:P ratio from 1.2:1 to 1.6:1 to 2.0:1, ymax in P accretion increased from 0.91 to 0.97 to 1.03 g/duck during the 5-d period of measurement, and marginal efficiency of utilization (deltay/deltax) of P from MCP increased from 75 to 85 to 91%. The overall utilization of plant P from the low-P basal diet was adversely affected by increasing dietary Ca:P ratio and decreased from 49 to 45 to 40%. Seven inorganic P sources were supplemented to a low-P basal diet to increase P content by 0.9 or 1.9 g/kg. Utilization of P from the sources was lower at 1.9 g/kg compared with at 0.9 g/kg, although supply was still below requirement, indicating that ducks fed 1.9 g/ kg were in the diminishing part of the response curve. Thus, only the values determined at the low level of supplementation were considered as a measure of availability. P availabilities were 100% for monosodium phosphate, 96% for anhydrous dibasic calcium phosphate, 92% for calcium sodium magnesium phosphate, 91% for monodibasic calcium phosphate, 86% for 2 batches of dihydrated dibasic calcium phosphate, and 77% for calcium sodium phosphate. It was concluded that availability studies aiming to characterize the capacity of an ingredient require standardization with regard to the level of P supply and the dietary Ca:P ratio. Similar to results from other species, the availability of inorganic feed phosphates for ducks is on an overall high level, but differences between P sources should be considered in diet formulation.

Animals↗

PubMed1999

The importance of pyruvate availability to PDC activation and anaplerosis in human skeletal muscle.

No studies have singularly investigated the relationship between pyruvate availability, pyruvate dehydrogenase complex (PDC) activation, and anaplerosis in skeletal muscle. This is surprising given the functional importance attributed to these processes in normal and disease states. We investigated the effects of changing pyruvate availability with dichloroacetate (DCA), epinephrine, and pyruvate infusions on PDC activation and accumulation of acetyl groups and tricarboxylic acid (TCA) cycle intermediates (TCAI) in human muscle. DCA increased resting PDC activity sixfold (P < 0.05) but decreased the muscle TCAI pool (mmol/kg dry muscle) from 1.174 +/- 0.042 to 0.747 +/- 0.055 (P < 0.05). This was probably a result of pyruvate being diverted to acetyl-CoA and acetylcarnitine after near-maximal activation of PDC by DCA. Conversely, neither epinephrine nor pyruvate activated PDC. However, both increased the TCAI pool (1.128 +/- 0.076 to 1.614 +/- 0.188, P < 0.05 and 1.098 +/- 0.059 to 1.385 +/- 0.114, P < 0.05, respectively) by providing a readily available pool of pyruvate for anaplerosis. These data support the hypothesis that TCAI pool expansion is principally a reflection of increased muscle pyruvate availability and, together with our previous work (J. A. Timmons, S. M. Poucher, D. Constantin-Teodosiu, V. Worrall, I. A. Macdonald, and P. L. Greenhaff. J. Clin. Invest. 97: 879-883, 1996), indicate that TCA cycle expansion may be of little functional significance to TCA cycle flux. It would appear therefore that the primary effect of DCA on oxidative ATP provision is to provide a readily available pool of acetyl groups to the TCA cycle at the onset of exercise rather than increasing TCA cycle flux by expanding the TCAI pool.

Adult↗

PubMed1992

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↗

PubMedDate not supplied

Phosphorus sorption and availability in soils amended with animal manures and sewage sludge.

Soils that receive large applications of animal wastes and sewage sludge are vulnerable to releasing environmentally significant concentrations of dissolved P available to subsurface flow owing to the gradual saturation of the soil's P sorption capacity. This study evaluated P sorption (calculated from Langmuir isotherms) and availability of P (as CaCl2-P and resin P) in soils incubated for 20 d with poultry litter, poultry manure, cattle slurry, municipal sewage sludge, or KH2PO4, added on a P-equivalent basis (100 mg P kg(-1)). All the P sources had a marked negative effect on P sorption and a positive effect on P availability in all soils. In the cattle slurry- and KH2PO4-treated soils, the decreases in P sorption maximum (19-66%) and binding energy (25-89%) were consistently larger than the corresponding decreases (7-41% and 11-30%) in poultry litter-, poultry manure-, and sewage sludge-treated soils. The effects of cattle slurry and KH2PO4 on P availability were, in most cases, larger than those of the other P sources. In the poultry litter, poultry manure, and sewage sludge treatments, the increase in soil solution P was inversely related (R2 = 0.75) to the input of Ca from these relatively high Ca (13.5-42 g kg(-1)) sources. Correlation analyses implied that the magnitude of the changes in P sorption and availability was not related to the water-extractable P content of the P sources. Future research on the sustainable application of organic wastes to agricultural soils needs to consider the non-P- as well as P-containing components of the waste.

Adsorption↗

PubMed1985

Biologically available iodine in goitrogenic diets.

Eight different sources of low-iodine diet (LID) were tested in mice over 14 years. The available iodine in each diet was measured by isotopic equilibration. Commercially prepared Remington diets contained 6.8 to 69.3 ng available iodine/g, and the results were usually different from shipment to shipment. Some samples produced greatly enlarged thyroids. The Remington diets from two sources were occasionally low in iodine but produced little thyroid enlargement. Between 1977 and 1980 only one shipment of Remington diet was found to contain less than 10 ng available I/g, and it resulted in large goiters. Since 1980 other compositions of LID have been used, but they caused additional abnormalities during breeding or chronic feeding. A low-iodine wheat diet produced goiter in mice more readily than in rats. In the course of testing for unavailable forms of dietary iodine, it was found that only 34.2% of thyroxine iodine was available to the thyroid iodine pool of mice. It is concluded that unidentified nutritional deficiency or dietary contaminants can alter the goitrogenic response to restricted iodine intake. Furthermore, at least one natural form of potential dietary iodine is incompletely available to mice.

Animals↗