Hydrolysis Of Nutrients Research Articles

Construction of borate-ester-based COFs with high specific surface area for the detection of H2O content in the food field

Excessive H2O content in food will cause the hydrolysis of nutrients and provide a favorable environment for the growth of mycotoxins, thus, developing fast response, low detection limit, and high detection capacity sensors is urgently needed for food quality and safety. In this work, we developed two borate-ester-based covalent organic frameworks (COF-5 and COF-10) with high specific surface areas (1189.0 m2·g−1 and 1105.1 m2·g−1), which exhibited rapid response (COF-5 about 40 s and COF-10 about 35 s), good linearity (COF-5:R2=0.9981 and COF-10:R2=0.9993), and low detection limits (LODCOF-5=0.044 v/v% and LODCOF-10=0.016 v/v%). DFT theoretical calculation demonstrated that H2O participated in the partial hydrolysis of the B-O bond, resulting in the enhancement of fluorescence. Based on the good fluorescence properties, these two probes had been successfully used to quantificationally detect H2O content in honey, corn starch, and milk powder with satisfactory results, indicating an excellent application potential in the food field.

Digestion In The Duodum 12

The Duodenum Is Called The Central Link Of Digestion. The Acidic Gastric Chyme That Enters The Intestine Is Alkalized Under The Influence Of Digestive Juices, Which Creates An Optimal Environment For Further Hydrolysis Of Nutrients. Three Digestive Juices Are Secreted Into The Cavity Of The Duodenum: Pancreatic, Intestinal And Bile. Pancreatic Juice. The Exocrine Elements Of The Pancreas Secrete Pancreatic Juice, Which Is Secreted Through The Ducts Into The Duodenal Cavity. 1.5–2.5 Liters Of Juice Is Formed Per Day. Pancreatic Juice Is A Colorless Transparent Liquid. Composition Of Pancreatic Juice: 99% - Water, 1% - Dry Residue. The Dry Residue Consists Of Inorganic And Organic Substances. Inorganic Substances Are Represented By Sodium, Potassium, Calcium, Magnesium Chlorides, Sulfates And Phosphates

Cell wall of feeds and their impact on protein digestibility: An in vitro method applied for pig nutrition

Plant-derived by-products of the food, drink, and fuel industry are low-cost ingredients, that are routinely used to formulate feeds for livestock, especially for pigs. Often, those ingredients are rich in dietary fibres (DF), which is known to have a negative influence on the digestive use of nutrients in pigs. The effect of DF on nutrient bioaccessibility (i.e., the release of nutrients from the plant tissue) and digestion (i.e., transformation of the plant tissue during digestion and the hydrolysis of nutrients by digestive enzymes) depends on their amount, but more importantly, on their nature and organisation within the cell wall. The aim of this work was to determine how DF from different sources affected protein bioaccessibility and proteolysis. We hypothesised that protein released from the feed matrix and hydrolysis in pig feed depend mainly on the nature and amount of cell wall polysaccharides (i.e., dietary fibre). To test this, we conducted an in vitro study where nine feed ingredients commonly used in pig feeding (i.e., soybean meal, barley, wheat, two varieties of peas, fava bean, chickpea, maize and sugar beet pulp) were digested using a simulated gastrointestinal digestion model. Cell wall integrity and proteolysis were assessed using biochemical, biophysical, and microscopic techniques. Protein bioaccessibility differed among the ingredients (P < 0.01), with sugar beet pulp and maize having the lowest fraction of protein released from the plant tissue (about 34 %) and chickpea the greatest (93 %). Protein hydrolysis values also varied greatly among the ingredients (P < 0.01) but did not always follow the same trend as that of bioaccessibility. For instance, soybean meal had the highest protein hydrolysis with 96 % and sugar beet pulp the lowest with 50 %. The particle size distribution and microscopy images provide an explanation for these differences, related to the physical barrier, swelling, and rupture of the cell wall. This study illustrated that the cell wall structure is specific for each ingredient, with consequences on bioaccessibility and digestibility that cannot be characterised by the composition in DF alone. In feed formulation, this concept ought to be accounted for to achieve optimal use and uptake of nutrients by the animal.

In vitro digestion of whole chia seeds (Salvia hispanica L.): Nutrient bioaccessibility, structural and functional changes

AbstractDietary chia seed (Salvia hispanica L.) has significant health‐related benefits due to its high nutrient contents. However, few studies reported the fate of whole seeds in the gastrointestinal tract. Herein, we explored the digestive characteristics in terms of hydrolysis of nutrients, structural and functional properties with a static in vitro digestion method. After gastrointestinal digestion, the digestibility of lipid and protein was 0.46% and 11.38%, respectively. The release rates of tryptophan, tyrosine and lysine were greater than 20%, whereas the glutamic acid and aspartic acid were less than 5%. The microscopic results (optical microscopy (OM), laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM)) demonstrated that the seeds remained intact, and the mucilage adhered tightly to the seed coat during digestion. The water holding capacity and oil holding capacity of seeds accounted for 6.37 and 3.28 g/g after intestinal digestion, which were significantly lower than gastric digestion endpoints (P &lt; 0.05). And there were no significant differences in Fourier transform infrared spectroscopy of G‐Mucilage and I‐Mucilage. In general, preprocessing before being consumed is necessary for chia seeds to take full advantage of rich polyunsaturated fatty acids and proteins.

Small and Large Intestine (I): Malabsorption of Nutrients.

Numerous disorders can alter the physiological mechanisms that guarantee proper digestion and absorption of nutrients (macro- and micronutrients), leading to a wide variety of symptoms and nutritional consequences. Malabsorption can be caused by many diseases of the small intestine, as well as by diseases of the pancreas, liver, biliary tract, and stomach. This article provides an overview of pathophysiologic mechanisms that lead to symptoms or complications of maldigestion (defined as the defective intraluminal hydrolysis of nutrients) or malabsorption (defined as defective mucosal absorption), as well as its clinical consequences, including both gastrointestinal symptoms and extraintestinal manifestations and/or laboratory abnormalities. The normal uptake of nutrients, vitamins, and minerals by the gastrointestinal tract (GI) requires several steps, each of which can be compromised in disease. This article will first describe the mechanisms that lead to poor assimilation of nutrients, and secondly discuss the symptoms and nutritional consequences of each specific disorder. The clinician must be aware that many malabsorptive disorders are manifested by subtle disorders, even without gastrointestinal symptoms (for example, anemia, osteoporosis, or infertility in celiac disease), so the index of suspicion must be high to recognize the underlying diseases in time.

ASAS-NANP symposium: digestion kinetics in pigs: the next step in feed evaluation and a ready-to-use modeling exercise

Growing importance of upcycling agricultural by-products, food waste, and food processing by-products through livestock production strongly increased the variation in the nutritional quality of feed ingredients. Traditionally, feed ingredients are evaluated based on their measured extent of digestion. Awareness increases that in addition to the extent, the kinetics of digestion affects the metabolic fate of nutrients after absorption. Together with a growing body of evidence of complex interactions occurring within the lumen of the digestive tract, this urges the need of developing new approaches for feed evaluation. In a recently developed approach, we propose combining in vitro and in silico methods for feed ingredient evaluation. First steps in the development of such a systems were made by (1) evaluating in vitro the digestion potential of feed ingredients, regarding this as true ingredient properties and (2) predicting in silico the digestive processes like digesta transit, nutrient hydrolysis and absorption using dynamic, mechanistic modeling. This approach allows to evaluate to what extent the digestion potential of each ingredient is exploited in the digestive tract. Future efforts should focus on modeling digesta physicochemical properties and transit, applying in vitro digestion kinetic data of feed ingredients in mechanistic models, and generating reliable in vivo data on nutrient absorption kinetics across feed ingredients. The dynamic modeling approach is illustrated by a description of a modeling exercise that can be used for teaching purposes in digestive physiology or animal nutrition courses. A complete set of equations is provided as an on-line supplement, and can be built in modeling software that is freely available. Alternatively, the model can be constructed using any modeling software that enables the use of numerical integration methods.

ОСОБЕННОСТИ СОСТОЯНИЯ МИКРОЦИРКУЛЯТОРНОГО РУСЛА И МЕМБРАННОГО ПИЩЕВАРЕНИЯ У НОВОРОЖДЕННЫХ ТЕЛЯТ ПРИ ДИСПЕПСИИ

The scientific article provides information about the study of the features of blood supply, the state of the microcirculatory bed in clinically healthy newborn calves, as well as in the case of their dyspepsia. It was found that in clinically healthy newborn calves, the microcirculatory bed of the conjunctiva of the eyeball is represented by all the links of microcirculation, namely: parallel arterioles and venules that end in the corresponding capillaries, they form a cellular structure on the conjunctiva. In calves with dyspepsia, there are marked changes in the microcirculation of certain areas of the conjunctiva of the eyeball. In this case, microcirculatory disorders are characterized by a change in the shape of the vessels, the unevenness of their caliber, the appearance of ampouleshaped extensions along the course of the vessels, the appearance of constrictions in them. The ratio of the diameter of the venules of the diameter of the arterioles is 1:4, and in healthy calves this ratio is 1:2. Intravascular changes are characterized by the appearance of aggregation of red blood cells (sludge phenomenon) in most vessels of the venular bed, as well as in capillaries and isolated cases in arterioles. Against the background of pronounced disorders in the microcirculatory bed, and as is known, they reflect a systemic circulatory disorder, we conducted parallel studies of membrane digestion, using the example of protein hydrolysis. It was found that in sick calves, there was a decrease in the enzymatic activity of glycyl-L-leucine dipeptidase along the proximal gradient. Thus, in calves with dyspepsia, there is a disorder of blood circulation in general and in the digestive system in particular, which is a determining factor in the occurrence of disorders of membrane digestion, which performs the intermediate and final stages of hydrolysis of nutrients.

309 ASAS-EAAP Talk: Modelling digestion kinetics: the next step in the evaluation of feed ingredients

Abstract There is increasing importance of upcycling of low-opportunity-cost feed, food waste, and food processing byproducts into animal products, strongly increasing the variation in the nutritional quality of feed ingredients. Traditionally, feed ingredients are evaluated based on their measured extent of digestion. Increasing awareness that not only the total yield of nutrients, but also their absorption kinetics, affect their metabolic fate after absorption, and a growing body of evidence of complex interactions taking place inside the gastro-intestinal tract urges development of new approaches. In a recently developed approach (Schop, 2020), we propose a combination of in vitro methodology and dynamic modelling of the digestion process as an alternative to conventional feed ingredient evaluation, and made the first steps in the development of such a system. The digestion potential, evaluated in vitro, is considered as the true property of feed ingredients. Then, prediction of digesta transit, nutrient hydrolysis and absorption, following the intake of a complete feed, determines the extent to which the digestion potential of each ingredient is exploited. The dynamic, mechanistic model developed by Schop for growing pigs comprises 48 state variables representing dietary nutrients, hydrolysis products, endogenous components, and microbial biomass. Driving variables are ingested nutrients from feed ingredients, characterized in vitro (solubility, undegradable fraction, maximum rate of digestion). Passage of digesta is modelled as a function of nutrient solubility, diet viscosity and feed intake. The extent of protein digestion and extent and rate of starch digestion, but not absorption of amino acids, were adequately predicted by the model. Future efforts should focus on modelling digesta properties and transit, translation of in vitro digestion kinetic data and generating reliable in vivo data on nutrient absorption kinetics across feed ingredients. Schop, T.A. 2020 Modelling digestion kinetics in pigs. Predicting nutrient absorption based on diet and ingredient properties. PhD thesis, Wageningen University, Wageningen, NL.

In vitro digestion models to assess lipolysis: The impact of the simulated conditions of gastric and intestinal pH, bile salts and digestive fluids

In vitro digestion models are a valid methodology to study nutrient hydrolysis by simulating standard physiological gastrointestinal conditions. However, there are pathologies in which some conditions are affected, which should be considered in the design of an in vitro digestion study. Our work aims at elucidating the role of different gastrointestinal conditions on lipolysis. In the context of exocrine pancreatic insufficiency, gastric pH, intestinal pH, bile salts composition, bile salts concentration, fat concentration in the digestion medium and volumetric ratio digestion fluid/food were the selected study parameters. The pH-stat method was applied to assess lipolysis extent and kinetics. Descriptive results were summarised in digestibility curves and beta regression models were used to explain the effect (odds ratio, OR) of the studied conditions on lipolysis. Additionally, distribution of emulsion droplets was measured and optical microscopy images of fat globules were taken in a selection of experimental conditions. Results showed that intestinal pH was the variable with the highest effect on lipolysis (OR 22.86, p < 0.001), followed by fat concentration in the digestion medium (OR 6.76, p < 0.001) and bile salts concentration (OR 1.56, p < 0.001). Overall, lipolysis was significantly associated with particle size (OR - 6.98, p < 0.001). We conclude that the assessment of lipolysis by means of in vitro digestion models is sensitive to the simulated gastrointestinal conditions, which should be adapted to the real physiological conditions occurring in altered health conditions.

Fat digestibility in meat products: influence of food structure and gastrointestinal conditions

Digestibility of macronutrients depends on the food matrix structure as well as on gastrointestinal conditions, especially in patients with exocrine pancreatic insufficiency. In this situation, an oral enzyme supplementation that promotes nutrient hydrolysis is needed. In this context, in the present study, a static in vitro digestion model was used to assess the lipid digestibility of different meat products (processed and fresh), different intestinal conditions of pH (6 or 7), bile concentration (1 or 10 mM) and doses of the enzyme supplement (1000–4000 lipase units/g fat). Results showed that processed (unstructured) meats had better matrix degradation during digestion and reached higher values of lipolysis extents (total free fatty acids/g fat) than the natural meat matrices with a statistically significant association (p < .001). Regarding the intestinal medium, pH of 7 and bile concentration of 10 mM contribute to higher matrix degradation and thus, to a higher lipolysis (p < .001).

Activity of hydrolytic enzyme in the poultry of different species

In the processes of digestion and assimilation of nutrients of feed in the body a special place belongs to the digestive system. Hydrolysis of nutrients in the gastrointestinal tract of farm poultry is closely linked to its physiological state, the intensity of metabolic processes in the body and its productivity. However, there are no significant differences in the course and regulation of digestive functions between individual poultry species. At the same time, for different types of poultry, certain distinctive patterns of the course of digestive processes and, in particular, the activity of hydrolytic enzymes, due to the peculiarities of the structure and functioning of the digestive system, are characteristic. In the article is given a fragment of complex systemic researches, which is concerning the proteolytic, amylolytic and lipolytic activity of enzymes in tissues of the organs of the digestive canal (mucous membrane of the glandular and duodenum, pancreas, liver) of the quail breed “Pharaoh”, as well as chicken egg productivity direction cross “Hayseks Brown” and the Beijing Broiler Duck Cross STAR 53 (heavy) selection of the French firm “GRIMAUD FRERES SELECTION” during the critical periods of their growth and development. Namely, in the period of adaptation of the organism after hatching (day-old chicks of all species), complete resorption of residual yolk (7-day quail and 6-day chickens and ducks) and puberty (120-day chickens, 42-day quails, 180-daily ducks) All poultry was kept in poultry farms and received balanced full-fodder feeds, taking into account its species, age and physiological condition. The technology of keeping quails and chickens in cellular batteries, and ducks – on the mesh floor, with free access to the feed and water. It was established, that the nature of changes in the activity of hydrolytic enzymes had organ-tissue and species specificity. This is due not only to the particularities of digestion in quails, chickens and ducks, but also the energy value of rations used in feeding each type of farm poultry, which significantly affects metabolic processes in the body.

Modelling digestive hydrolysis of nutrients in fish using factorial designs and desirability function.

Models simulating the in vitro digestive hydrolysis of nutrients by different animal species are frequently used to obtain a better understanding of factors affecting this process. Optimization algorithm of a model may be used to prospect the more favourable combination of selected factors resulting in the higher performance. This study was conducted to determine the combination of factors (pH, enzyme:substrate ratio, and reaction time) leading to highest bioavailability of proteins and carbohydrates in the gilthead seabream gastrointestinal tract. Besides, a novel multi-objective algorithm, desirability function, was introduced for optimization of the digestive hydrolysis of nutrients within the simulated gut of the species, using models based on the Response Surface Methodology. Design of experiment was defined based on the physiology and culture conditions of the species, and in vitro assays were performed in a two-phase (stomach ad intestine) digestion process, using the species-specific enzyme extract. According to results, intestinal phase of digestion makes the major contribution to the total protein hydrolysis, being the efficiency of the process directly correlated to all the three studied factors. In contrast, the efficiency of carbohydrate hydrolysis was directly correlated to the amount of substrate and inversely to the pH, while reaction time did not exert a significant effect. The physiological range of the factors studied in the assays favoured the hydrolysis of proteins over carbohydrates, a similar scenario to that observed in the live fish. Results from the mathematical models and their simultaneous optimization obtained from this work may have practical applications in design of feeds for this species.

Effect of cooking methods and intestinal conditions on lipolysis, proteolysis and xanthophylls bioaccessibility of eggs

Digestibility of macro and micronutrients depends on the ingested food as well as on gastrointestinal conditions, being those suboptimal in exocrine pancreatic insufficiency (EPI) patients. Under this scenario, oral enzyme supplementation improves enzymatic hydrolysis of nutrients. In this study, a static in vitro model was used to assess lipids and protein digestibility as well as lutein and zeaxanthin bioaccessibility of eggs cooked differently and submitted to different intestinal conditions. Boiled, poached and omelette eggs were digested under different intestinal conditions of pH (6 or 7), bile concentration (1 or 10 mM) and doses of the enzyme supplement (1000–4000 LU/g fat). Results showed that poaching resulted in higher digestibility of lipids and proteins, compared to boiling or omelette preparations, under gastrointestinal conditions of EPI (pH 6, bile 1 mM). Concerning xanthophylls bioaccessibility, boiling and poaching led to higher bioaccessibility of lutein and zeaxanthin than omelette under EPI conditions.

ВОЗРАСТНАЯ ДИНАМИКА СТРУКТУРНЫХ И ЦИТОХИМИЧЕСКИХ ПОКАЗАТЕЛЕЙ ТОЩЕЙ КИШКИ КРЫС

Background. The functions of the jejunum are diverse, but all of them to some extent ensure the implementation of the two leading processes in the body: hydrolysis of nutrients that have been taken and their absorption. Objective: to study, in normal conditions, the features of the age-related formation of structural and cytochemical indices of the jejunum of rats in postnatal ontogenesis. Material and methods. The experiment was performed on 35 rats of 15-, 45- and 90-day old age. A complex of histological, histochemical, electron microscopic methods was used with subsequent morphometric and statistical analysis. Results. It was established that the structural organization of the jejunum develops intensively from the 15th to the 45th day, which is probably due to the transition from dairy to definitive type of nutrition. Conclusions. The microvillous epithelium is already completely formed by the 15th day and has a high structural and cytochemical organization providing an intensive level of parietal digestion right after birth and absorption of the monomers that form.

The Secretion and Action of Brush Border Enzymes in the Mammalian Small Intestine.

Microvilli are conventionally regarded as an extension of the small intestinal absorptive surface, but they are also, as latterly discovered, a launching pad for brush border digestive enzymes. Recent work has demonstrated that motor elements of the microvillus cytoskeleton operate to displace the apical membrane toward the apex of the microvillus, where it vesiculates and is shed into the periapical space. Catalytically active brush border digestive enzymes remain incorporated within the membranes of these vesicles, which shifts the site of BB digestion from the surface of the enterocyte to the periapical space. This process enables nutrient hydrolysis to occur adjacent to the membrane in a pre-absorptive step. The characterization of BB digestive enzymes is influenced by the way in which these enzymes are anchored to the apical membranes of microvilli, their subsequent shedding in membrane vesicles, and their differing susceptibilities to cleavage from the component membranes. In addition, the presence of active intracellular components of these enzymes complicates their quantitative assay and the elucidation of their dynamics. This review summarizes the ontogeny and regulation of BB digestive enzymes and what is known of their kinetics and their action in the peripheral and axial regions of the small intestinal lumen.

BOARD-INVITED REVIEW: Opportunities and challenges in using exogenous enzymes to improve nonruminant animal production

Diets fed to nonruminant animals are composed mainly of feed ingredients of plant origin. A variety of antinutritional factors such as phytin, nonstarch polysaccharides, and protease inhibitors may be present in these feed ingredients, which could limit nutrients that may be utilized by animals fed such diets. The primary nutrient utilization-limiting effect of phytin arises from the binding of 6 phosphate groups, thus making the P unavailable to the animal. The negative charges allow for formation of insoluble phytin-metal complexes with many divalent cations. Furthermore, phytin and protein can form binary complexes through electrostatic links of its charged phosphate groups with either the free amino group on AA on proteins or via formation of ternary complexes of phytin, Ca(2+), and protein. The form and extent of de novo formation of binary and ternary complexes of phytin and protein are likely to be important variables that influence the effectiveness of nutrient hydrolysis in plant-based diets. Nonstarch polysacharides reduce effective energy and nutrient utilization by nonruminant animals because of a lack of the enzymes needed for breaking down the complex cell wall structure that encapsulate other nutrients. Enzymes are used in nonruminant animal production to promote growth and efficiency of nutrient utilization and reduce nutrient excretion. The enzymes used include those that target phytin and nonstarch polysaccharides. Phytase improves growth and enhances P utilization, but positive effects on other nutrients are not always observed. Nonstarch polysaccharide-hydrolyzing enzymes are less consistent in their effects on growth and nutrient utilization, although they show promise and it is imperative to closely match both types and amounts of nonstarch polysaccharides with appropriate enzyme for beneficial effects. When used together with phytase, nonstarch polysaccharide-hydrolyzing enzymes may increase the accessibility of phytase to phytin encapsulated in cell walls. The future of enzymes in nonruminant animal production is promising and will likely include an understanding of the role of enzyme supplementation in promoting health as well as how enzymes may modulate gene functions. This review is an attempt to summarize current thinking in this area, provide some clarity in nomenclature and mechanisms, and suggest opportunities for expanded exploitation of this unique biotechnology.

Are levels of digestive enzyme activity related to the natural diet in passerine birds?

Digestive capabilities, such as the rates nutrient hydrolysis and absorption, may affect energy intake and ultimately feeding behavior. In birds, a high diversity in gut biochemical capabilities seems to support the existence of a correlation between the morphology and physiology of the intestinal tract and chemical features of the natural diet. However, studies correlating the activity of digestive enzymes and the feeding habits at an evolutionary scale are scarce. We investigated the effect of dietary habits on the digestive physiological characteristics of eight species of passerine birds from Central Chile. The Order Passeriformes is a speciose group with a broad dietary spectrum that includes omnivorous, granivorous and insectivorous species. We measured the activity of three enzymes: maltase, sucrase and aminopeptidase-N. Using an autocorrelation analysis to remove the phylogenetic effect, we found that dietary habits had no effect on enzymatic activity. However, we found that granivorous and omnivorous species had higher levels of disaccharidase activities and insectivores had the lowest. The major difference in enzymatic activity found at the inter-specific level, compared to the reported lower magnitude of enzyme modulation owing to dietary acclimation, suggests that these differences to some extent have a genetic basis. However, the lack of a clear association between diet categories and gut physiology suggested us that dietary categorizations do not always reflect the chemical composition of the ingested food.

Persistent decreased plasma cholecystokinin levels in celiac patients under gluten-free diet: respective roles of histological changes and nutrient hydrolysis

Celiac disease is associated with impaired cholecystokinin (CCK) release. The mechanism by which CCK release is impaired is poorly understood and seems to be related to the mucosal atrophy or to decreased stimulation due to reduced intraduodenal nutrient hydrolysis. The aims of our study were to evaluate basal and postprandial CCK in celiac patients presenting with distinctive types of mucosal lesions (normal, infiltrative and atrophic), and to study the role of protein hydrolysis on CCK release. Plasma CCK was measured in 20 celiac patients (normal mucosa: n=6; infiltrative type: n=6; atrophic type=8) and 9 controls, before and after ingestion of a polymeric or a semi-elemental meal. Significant decreases in basal CCK plasma (B 0.6 [95% CI, 0.3–1.3] pmol/l; p<0.003) and postprandial CCK area under curve (AUC 34 [19–61] pmol/l×120 min, p<0.0001) were observed in patients with an atrophic mucosa compared with treated patients (B 1.6 [1.0–2.4] pmol/l, AUC 267 [172–414] pmol/l×120 min) or healthy volunteers (B 1.0 [0.7–1.4] pmol/l, AUC 186 [131–264] pmol/l×120 min). A significant defective CCK release was also observed in patients with an infiltrative type: B 0.4 [0.2–0.7] pmol/l and AUC 56 [31–101] pmol/l×120 min; p<0.0001. Administration of a semi-elemental diet did not correct the defective CCK release. In conclusion, the decreased CCK levels observed in celiac patients are not strictly related to the mucosal atrophy but rather to the lymphocytic infiltrate. Administration of a predigested meal did not correct the impaired CCK release. Some inhibitory mechanism could be involved in the CCK cell dysfunction observed in celiac patients presenting with lesser degrees of disease activity.

Digestive Constraints and Nutrient Hydrolysis in Nestlings of Two Flamingo Species

Abstract In vertebrates, enzymatic activity levels in the small intestine are correlated with dietary composition. We examined enzymatic activity levels in juvenile specimens of two flamingo species, Phoenicoparrus andinus and Phoenicoparrus jamesi. Both species feed their chicks with esophageal secretions. Based on the chemical composition of these secretions in flamingoes, we predicted low activity levels of disaccharidases and higher activities of aminopeptidase-N and esterase. As predicted, sucrase was absent in P. andinus, and its activity was low in P. jamesi. Esterase and aminopeptidase-N activities were relatively high. Low maltase activity suggested the presence of carbohydrates in esophageal secretions. Digestive features can have consequences on the growth and survival of chicks. Hence the data presented here may be relevant to the maintenance and reproduction of wild and captive endangered flamingoes.

Recent advances in the study of the nutritional toxicity of kidney bean ( [formula omitted]) lections in rats

The main toxic component isolated from several varieties of kidney bean ( Phaseolus vulgaris ) is a haemagglutinating lectin. The inclusion in rat diets of raw kidney beans or purified bean lectins results in abnormal development of microvilli in the small intestine. Immunocytochemical investigations have provided evidence that this lesion is associated with the binding of lectins to the luminal surfaces of enterocytes. The lectin-induced disruption of intestinal microvilli may result in interference with the intermediate and final stages of nutrient hydrolysis in the gut. In nitrogen balance studies it was found that rats ingesting pure bean lectins were in negative nitrogen balance. These nitrogen losses may have been partly the result of systemic effects, possibly caused by a selective uptake of lectins by the gut.