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PubMed1981

Efficiency of conventional versus marker technique for shortening the time in digestion trials.

Investigation was carried out to determine the digestibility of the main nutrients (DM, CP and energy) in digestion trials using some roughages in order to reduce the collection period and to study the suitable time of the marker technique and its application. This study revealed the following results: (1) The average recovery of chromic oxide in feces were 99.71 +/- 3.75% in the 3rd day (after administrating the marker), 95.17 +/- 1.03% in the 5th day and 96.53 +/- 2.35% in the 7th day. It could be concluded that this marker is indigestible and could be used as an ideal one. (2) There were no significant differences between the digestibility values with the conventional method and those of the two short-period techniques (the first three days and the first five days collection periods). The percentage differences were not exceeding 6% except some deviations with CP digestibility in one trial (hay : rice straw mixture). These two methods seemed to be reliable in practice. (3) The same differences were found between the digestion coefficients, which conducted from the conventional method, and those of the marker technique using three times for collection except high deviations were found with one trial in the last two procedures. Using marker technique appeared promising from the 3rd day up to the 7th day after its administration.

Animal Feed↗
PubMed1983

Intake and digestibility of berseem (Medicago sativa) and Sorghum Abu 70 (Sorghum vulgare) forages by Sudan zebu cattle and desert sheep.

Two experiments were carried out with Sudan zebu cattle and desert sheep to study the voluntary intake and digestibility of berseem (Medicago sativa) and Abu 70 (Sorghum vulgare) forages when offered ad lib. alone and with supplements of molasses to the cattle and dura grain to the sheep. In both experiments the intake of berseem was significantly higher than Abu 70. Supplementation increased Abu 70 intake and while molasses significantly increased berseem intake by cattle, dura decreased its intake by sheep. On the basis of metabolic body size sheep showed a higher intake of these forages than cattle. There was no significant difference in DM digestibility between berseem and Abu 70 by cattle. Sheep digested berseem significantly better than Abu 70. Molasses and dura significantly increased the digestibility of Abu 70 by cattle and sheep but had no significant effect on the DM digestibility of berseem.

Animals↗
PubMed1992

Cholestane as a digestibility marker in the absorption of polyunsaturated fatty acid ethyl esters in Atlantic salmon.

Salmonid fish require long-chain n-3 fatty acids in their diet. The digestibility of different chemical forms of fish oil fatty acids, fed as triacylglycerols, free fatty acids or ethyl esters, was examined in 300 g farmed Atlantic salmon (Salmo salar) using cholestane as an indicator of fat absorption in lieu of the chromium oxide (Cr2O3) which is commonly used as a marker in digestibility studies. It was established that the two digestibility markers gave similar results. Conveniently, cholestane does not require a separate analysis if fatty acids are to be determined by appropriate gas-liquid chromatography. The long-chain polyunsaturated fatty acids were particularly well absorbed, the apparent digestibility being 90-98% when feeding triacylglycerols or free fatty acids. However, the digestibility of monounsaturated fatty acids (75-94%) was lower, and lower still for saturated fatty acids (50-80%). Ethyl esters of fatty acids were significantly less well absorbed (P less than 0.05) than were the corresponding fatty acids in free acid or triacylglycerol form. Irrespective of dietary fat type, only free fatty acids were identified in feces, indicating total hydrolysis of triacylglycerols and ethyl esters.

Animals↗
PubMed2004

Genetic diversity associated with variation in silage corn digestibility for three O-methyltransferase genes involved in lignin biosynthesis.

Polymorphisms within three candidate genes for lignin biosynthesis were investigated to identify alleles useful for the improvement of maize digestibility. The allelic diversity of two caffeoyl-CoA 3-O-methyltransferase genes, CCoAOMT2 and CCoAOMT1, as well as that of the aldehyde O-methyltransferase gene, AldOMT, was evaluated for 34 maize lines chosen for their varying degrees of cell wall digestibility. Frequency of nucleotide changes averaged one SNP every 35 bp. Ninety-one indels were identified in non-coding regions and only four in coding regions. Numerous distinct and highly diverse haplotypes were identified at each locus. Numerous sites were in linkage disequilibrium that declined rapidly within a few hundred bases. For F4, an early flint French line with high cell wall digestibility, the CCoAOMT2 first exon presented many non-synonymous polymorphisms. Notably we found an 18-bp indel, which resembled a microsatellite and was associated with cell wall digestibility variation. Additionally, the CCoAOMT2 gene co-localized with a QTL for cell wall digestibility and lignin content. Together, these results suggest that genetic diversity investigated on a broader genetic basis could contribute to the identification of favourable alleles to be used in the molecular breeding of elite maize germplasm.

Alleles↗
PubMed2005

A dynamic continuous-flow dialysis system with on-line electrothermal atomic-absorption spectrometric and pH measurements for in-vitro determination of iron bioavailability by simulated gastrointestinal digestion.

A dynamic continuous-flow dialysis (CFD) method with on-line electrothermal atomic absorption spectrometric (ETAAS) and pH measurements for study of simulated gastrointestinal digestion has been developed for prediction of iron bioavailability. The method used to estimate mineral bioavailability was based on gastric digestion in a batch system then dynamic continuous-flow intestinal digestion. The intestinal digestion was performed in a dialysis bag placed inside a chamber containing a flowing stream of dialyzing solution. Mineral concentration and dialysate pH were monitored by ETAAS and use of a pH meter, respectively. The amount of dialyzed minerals in the intestinal digestion stage was used to evaluate the dialyzability. The dialysis profile and pH change can be used to understand or examine differences between the dialyzability of different food samples. To test the proposed system it was used to estimate the iron dialyzability of different kinds of milk. Iron dialyzability for powdered cow milk, cereal milk, and two brands of soymilk was found to be 1.7, 20.4, 24.9, and 37.7%, respectively. The developed CFD-ETAAS-pH system is a simple, rapid, and inexpensive tool for bioavailability studies, especially for minerals at ultratrace levels.

Animals↗
PubMed2003

Development of an in vitro digestion model for estimating the bioaccessibility of soil contaminants.

Soil ingestion can be a major route of human exposure to many immobile soil contaminants. The present risk assessment is based on toxicity studies in which contaminants are typically ingested in liquid or food matrices. The difference in bioavailability of contaminants ingested in a soil matrix is not taken into account. To become bioavailable, contaminants first need to become bioaccessible, i.e., they must be mobilized from the soil during digestion. Soil contaminants may be less bioaccessible than contaminants from liquid or food, so that the risks can be overestimated. This article describes the development of an in vitro human digestion model that is physiologically based. It can be used as a tool to assess bioaccessibility. We explain the rationale behind the experimental design of the model. We address the aspects of the simulated compartments of the gastrointestinal tract, temperature, soil-to-fluid ratio, ratio of digestive juices, transit times, centrifugation, pH values, mixing, constituents and their concentrations, and bile. The optimized in vitro digestion model was applied in a case study. The bioaccessibility of lead in pottery flakes with glazing was determined and compared to the bioaccessibility of lead in the soil from which the pottery flakes were removed. The data indicate that pottery flake lead is considerably less bioaccessible (0.3 +/- 0.2%) than lead in soil without pottery flakes (42-66% at the same site, and 28-73% at other sites in the same town). Furthermore, bioaccessibility values of lead in soil appear to be less than calculated bioaccessibility values for dietary lead (which are based on the criterion used by the Dutch risk assessment and on literature absorption data). This indicates that accounting for the matrix of ingestion can affect the exposure assessment for lead. The in vitro digestion model is a promising tool for studying the effect of the ingestion matrix on bioaccessibility.

Biological Availability↗
PubMed2004

Effect of bile type on the bioaccessibility of soil contaminants in an in vitro digestion model.

Soil ingestion is an important pathway of exposure for many nonvolatile contaminants for man and in particular for children. A fraction of the ingested contaminant may not dissociate from the soil particles during digestion in the gastrointestinal tract, and is thus not available for transport across the intestinal epithelium. In order to estimate the contaminant fraction that is mobilized from soil, i.e., the bioaccessible fraction, several in vitro digestion models have been developed. The currently existing digestion models display many differences. One aspect that may affect bioaccessibility and may induce differences between digestion models is the bile that is used. Often freeze-dried bile of animal origin is preferred to purified bile salts. However, also the animal origin of bile may give rise to differences in bioaccessibility because bile composition appears to be species dependent. In the present study, we compared the bioaccessibility of benzo[a]pyrene, arsenic, cadmium, and lead of four different soils after digestion with ox bile from two different suppliers, pig bile, and chicken bile. Bioaccessibility appeared to vary amongst the different soils and contaminants. Only chicken bile increased the bioaccessibility of lead and cadmium significantly and relevantly for one of four soils. For chicken bile, the bioaccessibility of lead was 3-5.5 times greater than for the other bile types and the bioaccessibility of cadmium was 1.5 times greater. In all other cases, the bioaccessibility differences were less than 10%, which is considered irrelevant for risk assessment purposes.

Animals↗
PubMed2006

Digestive performance in five Mediterranean lizard species: effects of temperature and insularity.

Temperature sensitivity of digestive processes has important ramifications for digestive performance in ectothermic vertebrates. We conducted a comparative analysis of temperature effects on digestive processes [gut passage times (GPTs) and apparent digestive efficiencies (ADEs)] in five lacertid lizards occurring in insular (Podarcis erhardii, P. gaigeae), and mainland (P. muralis, P. peloponnesiaca, Lacerta graeca) Mediterranean environments. GPTs were negatively correlated to temperature with mainland taxa having 10-20% longer GPTs than island taxa. In contrast to previous studies that estimate ADEs using bomb calorimetry, we compare ADEs by analyzing discrete efficiencies for lipids, sugars and proteins at three temperature regimes (20, 25, and 30 degrees C); each of these categories produces different results. ADEs for lipids and sugars showed a monotonic increase with temperature whereas ADEs for proteins decreased with temperature. Island taxa had consistently higher ADEs than their mainland counterparts for lipids and for proteins but not for sugars. They are characterized by superior energy acquisition abilities despite significantly shorter GPTs. Their increased digestive performance relative to the mainland species appears to allow them to maximize energy acquisition in unproductive island environments where food availability is spatially and seasonally clustered.

Animals↗
PubMed2000

Digestive plasticity and the cost of acclimation to dietary chemistry in the omnivorous leaf-eared mouse Phyllotis darwini.

We examined the costs associated with acclimation in an omnivorous mouse (Phyllotis darwini) fed two contrasting diets (carbohydrate-rich and protein-rich). We studied the response of gut morphology and digestive performance in animals shifted to a novel diet at different developmental stages. When acclimated adult animals were shifted to the alternative diet, energy digestibility decreased. We also found long-term consequences to diet acclimation. Animals reacclimated for 15 days to an alternative diet did not increase digestive performance. Although no effects of diet on gut morphology were noted, a significant positive correlation between energy digestibility and small intestinal length was found, explaining most of the variability observed in energy digestibility. These results suggest that caution should be used when defining adaptive changes if the possible cost of acclimation is neglected.

Acclimatization↗
PubMed1997

Analysis of the distribution of glycoconjugates in the digestive gland of the bivalve mollusc Mytilus galloprovincialis by conventional and lectin histochemistry.

We examined the distribution and pattern of reactivity of a panel of 16 lectins in the digestive gland of the bivalve mollusc Mytilus galloprovincialis at the light-microscopic level. Various chemical treatments were applied in combination with lectins to differentiate between N- and O-linked oligosaccharides. Several control reactions were carried out, including replacement of lectins by buffer and incubation with their specific competitive inhibitors. Some lectins reacted selectively with particular cell types, thus revealing a cell-specific glycoconjugate distribution pattern which is possibly related to the metabolic role of each cell type in the digestive gland. Glycoconjugates containing glucosamine, mannose, and sulfated galactose were associated with the endolysosomal system of digestive cells. These glycoconjugates were also found in small vesicles randomly distributed in the cytoplasm of adipogranular cells in the connective tissue. However galactosamine residues appeared to be associated mainly with basophilic cells. Fucose residues did not exhibit a cell-specific distribution and appeared in small amounts homogeneously distributed throughout the digestive gland tissue. Conventional histochemical reactions for carbohydrate detection revealed moderate amounts of periodic-acid-Schiff-positive, neutral carbohydrates widely distributed in digestive and connective tissues. Among the acid carbohydrates, most cell types contained complex sulfated carbohydrates, but not carboxylated ones; this agreed well with the complete lack of sialic acid residues in all cell types studied, as observed by lectin histochemistry.

Animals↗
PubMed1999

Column and high-performance size exclusion chromatography applications to the in vivo digestibility study of a thermoxidized and polymerized olive oil.

This study aimed (i) to design an in vivo model to study fat digestibility, and (ii) to apply this design to test the in vivo digestibility of a highly thermoxidized olive oil. True digestibility of unheated olive oil was tested 2, 4, 6, and 7 h after administering 1 g of olive oil/100 g body weight to young adult Wistar rats by means of esophageal probes. Remaining gastrointestinal lumen fat showed an inversely linear relationship (r= -0.9932; P < 0.001) with the length of the experiment. A 4-h test was considered adequate because after this period, half of the oil administer still remains in the lumen, making it possible to accurately measure the different nondigested, nonabsorbed thermoxidized compounds. In a second experiment, fresh olive oil (3.6 mg polar content/100 mg oil) was heated at 180 degrees C for 50 h in the presence of air; the polar content in this oil rose to 46.0 mg/100 mg oil. After 4 h, the true digestibility coefficient of 50-h heated olive oil did not significantly change, although it tended to decrease (24%) with respect to the unheated oil. Silica gel column chromatography and high-performance size exclusion chromatography were used to quantify nonthermoxidized and thermoxidized products present in the oils and in the gastrointestinal lumen after these test periods. True digestibility of the different thermoxidized compounds from the heated oil was 30-40%, whereas that of thermoxidized compounds from the fresh oil was much higher (approximately 80%). Nonoxidized triacylglycerol hydrolysis was negatively affected by the presence of large amounts of thermoxidized compounds. The present proposed model seems to be a useful tool for the study of thermoxidized oils. Data also show that thermoxidized compounds from abused olive oil are poorly but actively hydrolyzed and absorbed in vivo.

Animals↗
PubMed1991

Milk lipid digestion in the neonatal dog: the combined actions of gastric and bile salt stimulated lipases.

Intragastric lipolysis may be particularly important for the digestion of milk lipid since milk fat globules are resistant to pancreatic lipase without prior disruption; milk bile salt stimulated lipase (BSSL) may supplement further intestinal hydrolysis. Previous information on gastric lipolysis has been based primarily on in vitro studies using artificial lipid emulsions containing a single component fatty acid and have focused on the preferential release of medium-chain fatty acids. The actual contribution of these enzymes to overall fat digestion in vivo on natural substrates has rarely been studied, however. The neonatal dog is an excellent model in the study of lipid digestion because, like the human, milk lipids are high in long-chain unsaturated fatty acids, milk contains BSSL and gastric lipase is the predominant lipolytic enzyme acting in the stomach. We used a combination of in vivo studies with in vitro incubations to investigate digestion of milk lipid by gastric and milk (BSSL) lipases in the suckling dog. In the first 4 weeks postpartum, 14-41% and 42-60% of milk triacylglycerol was hydrolyzed to primarily diacylglycerol and free fatty acid (FFA) in the first 30 and 60 min in the stomach, respectively. Milk lipid contained high levels (63%) of long-chain unsaturated fatty acids, which were preferentially released as FFA during in vivo gastric lipolysis, consistent with the actions and stereospecificity of gastric lipase. While levels of hydrolysis in gastric aspirates were significantly different (by age and time in stomach) at the start of in vitro studies, total hydrolysis in all incubation systems plateaued at about 65%, suggesting product inhibition by the long-chain FFA, but to a much lesser degree than previously expected from in vitro studies. The magnitude of in vivo intragastric lipolysis was 3- to 6-times greater than that predicted by in vitro assays using either milk lipid or labeled emulsion as substrate, respectively. Prior exposure to intragastric lipolysis resulted in 30% hydrolysis by BSSL compared to 5% hydrolysis without prior exposure. We suggest that previous in vitro studies have largely underestimated the actual degree of intragastric lipolysis that can occur and its activity on long-chain fatty acids; this study indicates the importance of the combined mechanisms of gastric lipase and BSSL to fat digestion in the suckling neonate.

Aging↗
PubMed1989

Growth of digestive diseases research funds and investigators supported by the National Institutes of Health.

The object of this paper is to analyze the growth of the digestive diseases research community supported by the National Institutes of Health, based primarily on data from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), during the 10-yr period of fiscal year 1977 through 1986. During that period, research dollars have increased threefold (1.5-fold when corrected for inflation), whereas the number of grants supported by those dollars has increased only 1.5-fold. This increase is similar to that of the entire National Institutes of Health. A greater percentage of grantees now have multiple grants and the cost of multiple grants is greater on a per grant basis. One-half of the funds support the research of only one-fourth of the grantees. The number of competing applications sent to the National Institute of Diabetes and Digestive and Kidney Diseases compared with those sent to the National Institutes of Health shows a smaller increase (26% vs. 40%), whereas more funds are being provided per grant. Ten of the 12 institutes within the National Institutes of Health are now reporting digestive disease research support, so that total support exceeded $200 million in fiscal year 1986. We conclude that the digestive diseases research community is growing very slowly.

Digestive System Diseases↗
PubMed1988

Enzyme-digestible swelling hydrogels as platforms for long-term oral drug delivery: synthesis and characterization.

A method was developed for synthesizing enzyme-digestible swelling hydrogels. Albumin molecules were modified using glycidyl acrylate to introduce vinyl groups. The functionalized albumin molecules participated as cross-linkers in the polymerization of vinyl monomers, such as acrylic acid or acrylamide. The extent of chemical modification of albumin was an important variable in controlling the cross-linking ability. The albumin in the synthesized hydrogels retained its property of enzymatic digestion by proteolytic enzymes. The kinetics of swelling and enzymatic digestion of the hydrogels were examined using various enzyme concentrations. It was observed that the digestion kinetics were largely determined by the relative concentrations of albumin and enzyme. The potential application of the enzyme-digestible swelling hydrogels as platforms for long-term oral drug delivery is discussed.

Acetaminophen↗
PubMed1996

Endocytosis by digest cells of the cattle tick Boophilus microplus: regulation by protein kinase C.

Endocytosis of fluorescently-labeled bovine serum albumin by digest cells of the gut of the cattle tick Boophilus microplus is inhibited by approx 60% in the presence of the tumour promoter 12-O-tetradecanoylphorbol 13-acetate. The results are consistent with a role for protein kinase C in regulating the uptake of blood meal by digest cells. Protein kinase C activity has been measured in the digest cell and the amount of enzyme has also been determined using a phorbol ester binding assay. The presence of a small number of specific protein kinase C substrates in the plasma membrane of the digest cell has been demonstrated. Preliminary experiments indicate that one of these substrates, a protein of approximately 30 kDa, is an integral membrane protein, part of which is exposed on the extracellular surface of the digest cell.

Amino Acid Sequence↗
PubMed2004

[Benefits of a thickened infant formula with lactase activity in the management of benign digestive disorders in newborns].

This study aimed at evaluating the interest of a thickened infant formula with lactase activity by comparison with a standard infant formula in the management of benign digestive disorders in infants. Infants of both sex (N =109), ranging in age from 0 to 3 months, were included in a randomised double blind trial. Infants went to the paediatrician because of benign digestive disorders such as regurgitation, eructation or hiccup, colic, persistent crying and/or meteorism. Nine hundred and three infants were included and randomised in two parallel groups: they consumed daily either the thickened infant formula with lactase activity or a standard infant formula. There were no significant difference in the infants included in both groups. Both formula were well accepted and tolerated. Growth of the infants and compliance during the study were identical and good in the two groups. The efficiency of the formula tested was showed on digestive symptoms through: a decrease of the intensity of the digestive discomforts more important in the test than in the standard formula group; a decrease of the intensity of the gaz significantly more important in the test than in the standard formula group; significant decreases in frequency and intensity of the gaz in the test group while there were no significant diminution in the standard group; This study showed the good tolerance, acceptability and efficiency of a thickened infant formula with lactase activity on benign digestive disorders of young infants.

Dietary Supplements↗
PubMed2006

Phenotypic flexibility of digestive system in Atlantic cod (Gadus morhua).

This study examined the restoration of the digestive capacity of Atlantic cod (Gadus morhua Linnaeus) following a long period of food deprivation. Fifty cod (48 cm, 1 kg) were food-deprived for 68 days and then fed in excess with capelin (Mallotus villosus Müller) on alternate days. Ten fish were sampled after 0, 2, 6, 14 and 28 days and the mass of the pyloric caeca, intestine and carcass determined. Two metabolic enzymes (cytochrome c oxidase and citrate synthase) were assayed in white muscle, pyloric caeca and intestine, and trypsin activity was measured in the pyloric caeca. A delay of 14 days was required before body mass started to increase markedly, whereas most of the increase in mass of both the pyloric caeca and intestine relative to fish length occurred earlier in the experiment. By day 14, the activities of trypsin and citrate synthase in the pyloric caeca as well as citrate synthase in the intestine had reached maxima. The growth of the digestive tissues and restoration of their metabolic capacities thus occur early upon refeeding and are likely required for recovery growth to take place. The phenotypic flexibility of the cod digestive system is therefore remarkable: increases in trypsin activity and size of pyloric caeca resulted in a combined 29-fold increase in digestive capacity of the fish during the refeeding period. Our study suggests that Atlantic cod are able to cope with marked fluctuations in food availability in their environment by making a rapid adjustment of their digestive capacity as soon as food availability increases.

Animals↗
PubMed2006

Why substrate depletion has apparent first-order kinetics in enzymatic digestion.

A number of enzyme digestion assays show apparent first-order kinetics of reactant depletion. There are four possible explanations of this phenomenon: (i) the reaction is dominated by a first-order limiting step, (ii) the digestion follows a pseudo-first-order kinetics under the excess of a reactant species, (iii) the first-order kinetics is only applicable to the slow transient of the reaction, or (iv) the aggregate behavior of the reaction pathway produces behavior indistinguishable from the first-order kinetics. In this paper, we investigate the kinetics for protein digestion by formulating rate equations for two proposed mechanisms, namely the one-by-one mechanism and the zipper mechanism. Our analysis shows that the kinetics of protein digestion follows apparent first-order kinetics irrespective of the mechanism for low initial substrate concentration compared to the initial enzyme concentration. Also, our results provide an explanation for experimental observations and suggest a new experimental protocol that could reveal information on the mechanism of digestion.

Digestion↗