Search

Bioelectric signals possess the ability to robustly control and manipulate patterning during embryogenesis and tissue-level regeneration. Endogenous local and global electric fields function as a spatial 'pre-pattern', controlling cell fates and tissue-scale anatomical boundaries; however, the mechanisms facilitating these robust multiscale outcomes are poorly characterized. Computational modeling addresses the need to predict in vitro patterning behavior and further elucidate the roles of cellular bioelectric signaling components in patterning outcomes. Here, we modified a previously designed image pattern recognition algorithm to distinguish unique spatial features of simulated non-excitable bioelectric patterns under distinct cell culture conditions. This algorithm was applied to comparisons between simulated patterns and experimental microscopy images of membrane potential (V mem ) across cultured human iPSC colonies. Furthermore, we extended the prediction to a novel co-culture condition in which cell sub-populations possessing different ionic fluxes were simulated; the defining spatial features were recapitulated in vitro with genetically modified colonies. These results collectively inform strategies for modeling multiscale spatial characteristics that emerge in multicellular systems, characterizing the molecular contributions to heterogeneity of membrane potential in non-excitable cells, and enabling downstream engineered bioelectrical tissue design.

Diffusion is one of the key nature processes which plays an important role in respiration, digestion, and nutrient transport in cells. In this regard, the present article aims to review various diffusion approaches used to fabricate different functional materials based on hydrogels, unique examples of materials that control diffusion. They have found applications in fields such as drug encapsulation and delivery, nutrient delivery in agriculture, developing materials for regenerative medicine, and creating stimuli-responsive materials in soft robotics and microrobotics. In addition, mechanisms of release and drug diffusion kinetics as key tools for material design are discussed.

Human induced pluripotent stem cells (iPSCs) hold great promise for reducing the mortality of cardiovascular disease by cellular replacement of infarcted cardiomyocytes (CMs). CM differentiation via iPSCs is a lengthy multiweek process and is highly subject to batch-to-batch variability, presenting challenges in current cell manufacturing contexts. Real-time, label-free control quality attributes (CQAs) are required to ensure efficient iPSC-derived CM manufacturing. In this work, we report that live oxygen consumption rate measurements are highly predictive CQAs of CM differentiation outcome as early as the first 72 h of the differentiation protocol with an accuracy of 93%. Oxygen probes are already incorporated in commercial bioreactors, thus methods presented in this work are easily translatable to the manufacturing setting. Detecting deviations in the CM differentiation trajectory early in the protocol will save time and money for both manufacturers and patients, bringing iPSC-derived CM one step closer to clinical use., (© 2023 Wiley Periodicals LLC.)

Induced pluripotent stem cells (iPSCs) hold great promise in regenerative medicine; however, few algorithms of quality control at the earliest stages of differentiation have been established. Despite lipids having known functions in cell signaling, their role in pluripotency maintenance and lineage specification is underexplored. We investigated the changes in iPSC lipid profiles during the initial loss of pluripotency over the course of spontaneous differentiation using the co-registration of confocal microscopy and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging. We identified phosphatidylethanolamine (PE) and phosphatidylinositol (PI) species that are highly informative of the temporal stage of differentiation and can reveal iPS cell lineage bifurcation occurring metabolically. Several PI species emerged from the machine learning analysis of MS data as the early metabolic markers of pluripotency loss, preceding changes in the pluripotency transcription factor Oct4. The manipulation of phospholipids via PI 3-kinase inhibition during differentiation manifested in the spatial reorganization of the iPS cell colony and elevated expression of NCAM-1. In addition, the continuous inhibition of phosphatidylethanolamine N -methyltransferase during differentiation resulted in the enhanced maintenance of pluripotency. Our machine learning analysis highlights the predictive power of lipidomic metrics for evaluating the early lineage specification in the initial stages of spontaneous iPSC differentiation.

Urate oxidase (UOx) surrounded by synthetic macromolecules, such as polyethyleneimine (PEI), poly(allylamine hydrochloride) (PAH), and poly(sodium 4-styrenesulfonate) (PSS) is a convenient model of redox-active biomacromolecules in a crowded environment and could display high enzymatic activity towards uric acid, an important marker of COVID-19 patients. In this work, the carbon fiber electrode was modified with Prussian blue (PB) redox mediator, UOx layer, and a layer-by-layer assembled polyelectrolyte film, which forms a complex coacervate consisting of a weakly charged polyelectrolyte (PEI or PAH) and a highly charged one (PSS). The film deposition process was controlled by cyclic voltammetry and scanning electron microscopy coupled with energy-dispersive X-ray analysis (at the stage of PB deposition) and through quartz crystal microbalance technique (at latter stages) revealed uniform distribution of the polyelectrolyte layers. Variation of the polyelectrolyte film composition derived the following statements. (1) There is a linear correlation between electrochemical signal and concentration of uric acid in the range of 10 -4 -10 -6 M. (2) An increase in the number of polyelectrolyte layers provides more reproducible values for uric acid concentration in real urine samples of SARS-CoV-2 patients measured by electrochemical enzyme assay, which are comparable to those of spectrophotometric assay. (3) The PAH/UOx/PSS/(PAH/PSS) 2 -coated carbon fiber electrode displays the highest sensitivity towards uric acid. (4) There is a high enzyme activity of UOx immobilized into the hydrogel nanolayer (values of the Michaelis-Menten constant are up to 2 μM) and, consequently, high affinity to uric acid.

We suggest a new strategy for creating stimuli-responsive bio-integrated optical nanostructures based on Mie-resonant silicon nanoparticles covered by an ensemble of similarity negatively charged polyelectrolytes (heparin and sodium polystyrene sulfonate). The dynamic tuning of the nanostructures' optical response is due to light-induced heating of the nanoparticles and swelling of the polyelectrolyte shell. The resulting hydrophilic/hydrophobic transitions significantly change the shell thickness and reversible shift of the scattering spectra for individual nanoparticles up to 60 nm. Our findings bring novel opportunities for the application of smart nanomaterials in nanomedicine and bio-integrated nanophotonics., (© 2021 Wiley-VCH GmbH.)

New SERS detection platforms are required for the quick and easy preparation of sensing devices for food, agriculture, and environmental science. For quantitative sensing, it is important that a sensing material, in addition to efficient sensing, provides extraction and concentration of the target molecules such as toxic pesticides or healthy vitamins. We design such films adopting the Liesegang rings formation process that includes the reaction-diffusion of silver nitrate and melamine followed by the precipitation of different intermediates and their reduction by light in a pectin medium. Surprisingly, we find that the presence of melamine provides an excellent substrate for the extraction of pollutants at the solid-liquid interface giving rise to a powerful but easy and fast method for the quantification of fruits' quality. The complex silver and melamine containing films show high sensitivity even at relatively low silver concentrations.

In this paper, we describe an electrochemical sensing platform-ElectroSens-for the detection of Zn based on self-assembled polyelectrolyte multilayers on the carbon fiber (CF) electrode surface. The CF-extended surface facilitates the usage of a small volume electrochemical cell (1 mL) without stirring. This approach allows making a low-cost three-electrode platform. Working electrode modification with layer-by-layer assembly of polyethyleneimine (PEI), poly(sodium 4-styrenesulfonate) (PSS), and mercury nitrate layers eliminates solution toxicity and provides stable stripping voltammetry measurements. The stable, robust, sustainable, and even reusable Ag/AgCl reference electrode consists of adsorbed 32 PEI-KCl/PSS-KCl bilayers on the CF/silver paste separated from the outer solution by a polyvinyl chloride membrane. The polyelectrolyte-based sensor interface prevents adsorption of protein molecules from biological liquids on the CF surface that leads to a sensitivity increase of up to 2.2 μA/M for Zn 2+ detection and provides a low limit of detection of 4.6 × 10 -8 M. The linear range for Zn detection is 1 × 10 -7 to 1 × 10 -5 M. A portable potentiostat connected via wireless to a smartphone with an android-based software is also provided. The ElectroSens demonstrates reproducibility and repeatability of data for the detection of Zn in blood and urine without the digestion step., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Recommender systems (RSs), which underwent rapid development and had an enormous impact on e-commerce, have the potential to become useful tools for drug discovery. In this paper, we applied RS methods for the prediction of the antiviral activity class (active/inactive) for compounds extracted from ChEMBL. Two main RS approaches were applied: collaborative filtering (Surprise implementation) and content-based filtering (sparse-group inductive matrix completion (SGIMC) method). The effectiveness of RS approaches was investigated for prediction of antiviral activity classes ("interactions") for compounds and viruses, for which some of their interactions with other viruses or compounds are known, and for prediction of interaction profiles for new compounds. Both approaches achieved relatively good prediction quality for binary classification of individual interactions and compound profiles, as quantified by cross-validation and external validation receiver operating characteristic (ROC) score >0.9. Thus, even simple recommender systems may serve as an effective tool in antiviral drug discovery., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Recent outbreaks of dangerous viral infections, such as Ebola virus disease, Zika fever, etc., are forcing the search for new antiviral compounds. Preferably, such compounds should possess broad-spectrum antiviral activity, as the development of drugs for the treatment of dozens of viral infections lacking specific treatment would require significant resources. Antiviral activity data present in public resources are very sparse and further investigation of structure-activity relationships is necessary. One of the strategies could be the investigation of chemical space around known active compounds and assessment of activity against closely related viruses in order to fill in the antiviral activity matrix. Here we present an investigation of antiviral activity using universal maps built with generative topographic mapping (GTM) algorithm. The GTM-based maps were used to find commercially available compounds in close proximity to already known compounds with anti-flaviviral and anti-enteroviral activities. Selected compounds were then assessed in cell-based assays against tick-borne encephalitis virus (TBEV) and a panel of enteroviruses. This approach allowed us to identify 23 new compounds showing anti-TBEV activity with EC 50 values in micromolar and submicromolar range., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The discovery of antiviral drugs is a rapidly developing area of medicinal chemistry research. The emergence of resistant variants and outbreaks of poorly studied viral diseases make this area constantly developing. The amount of antiviral activity data available in ChEMBL consistently grows, but virus taxonomy annotation of these data is not sufficient for thorough studies of antiviral chemical space. We developed a procedure for semi-automatic extraction of antiviral activity data from ChEMBL and mapped them to the virus taxonomy developed by the International Committee for Taxonomy of Viruses (ICTV). The procedure is based on the lists of virus-related values of ChEMBL annotation fields and a dictionary of virus names and acronyms mapped to ICTV taxa. Application of this data extraction procedure allows retrieving from ChEMBL 1.6 times more assays linked to 2.5 times more compounds and data points than ChEMBL web interface allows. Mapping of these data to ICTV taxa allows analyzing all the compounds tested against each viral species. Activity values and structures of the compounds were standardized, and the antiviral activity profile was created for each standard structure. Data set compiled using this algorithm was called ViralChEMBL. As case studies, we compared descriptor and scaffold distributions for the full ChEMBL and its `viral' and `non-viral' subsets, identified the most studied compounds and created a self-organizing map for ViralChEMBL. Our approach to data annotation appeared to be a very efficient tool for the study of antiviral chemical space.

The development of stimuli-responsive nanocontainers is an issue of utmost importance for many applications such as targeted drug delivery, regulation of the cell and tissue behavior, making bacteria have useful functions and here converting light. The present work shows a new contribution to the design of polyelectrolyte (PE) containers based on surface modified mesoporous titania particles with deposited Ag nanoparticles to achieve chemical light upconversion via biofilms. The PE shell allows slowing down the kinetics of a release of loaded l-arabinose and switching the bacteria luminescence in a certain time. The hybrid TiO 2 /Ag/PE containers activated at 980 nm (IR) illumination demonstrate 10 times faster release of l-arabinose as opposed to non-activated containers. Fast IR-released l-arabinose switch bacteria fluorescence which we monitor at 510 nm. The approach described herein can be used in many applications where the target and delayed switching and light upconversion are required.

The development of sorbents for selective binding of cholesterol, which is a risk factor for cardiovascular disease, has a great importance for analytical science and medicine. In this work, two series of macroporous cholesterol-imprinted monolithic sorbents differing in the composition of functional monomers (methacrylic acid, butyl methacrylate, 2-hydroxyethyl methacrylate and ethylene dimethacrylate), amount of a template (4, 6 and 8 mol%) used for molecular imprinting, as well as mean pore size were synthesized by in situ free-radical process in stainless steel housing of 50 mm × 4.6 mm i.d. All prepared materials were characterized regarding to their hydrodynamic permeability and porous properties, as well as examined by BET and SEM methods. Imprinting factors, apparent dynamic dissociation constants, the maximum binding capacity, the number of theoretical plates and the height equivalent to a theoretical palate of MIP monoliths at different mobile phase flow rates were determined. The separation of a mixture of structural analogues, namely, cholesterol and prednisolone, was demonstrated. Additionally, the possibility of using the developed monoliths for cholesterol solid-phase extraction from simulated biological solution was shown., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Glucocorticoids (GCs) are used to treat numerous diseases, but their use in limited by adverse side effects. One such effect is occasional increased anxiety. Since the intensity of hepatic microsomal oxidation has been shown to alter responses to GC, we examined the possibility that rats with lower rates of hepatic GC metabolism would have increased anxiety. We hypothesized that the resulting, excessive GC would stimulate brain monoamine oxidase A (MAO-A), which would reduce brain serotonin, and thereby increase anxiety. Hepatic microsomal oxidative intensity was evaluated by the hexobarbital sleep time (HST) test. Results showed that rats with lower rates of hepatic GC metabolism had elevated brain MAO-A activity, reduced brain serotonin, and more anxiety than rats with higher rates of hepatic GC metabolism. We suggest that the HST test, as an integrative test of microsomal oxidation status, should be useful for predicting individual sensitivity to GC and to other drugs metabolized by the hepatic microsomal oxidation system.

The present study is focused on the relationship between monoamine oxidase (MAO) activity and hepatic content of cytochrome P450 (CYP), which reflects the status of microsomal oxidation. For vital integrative evaluation of hepatic microsomal oxidation in rats, the hexobarbital sleep test was used, and content of CYP was measured in hepatic microsomes. Rats with short hexobarbital sleep time (SHST) had higher content of microsomal CYP than rats with long hexobarbital sleep time (LHST). Whole brain MAO-A and MAO-B activities, serotonin and carbonylated protein levels were higher in SHST than in LHST rats. MAO-A and MAO-B activities were higher in brain cortex of SHST rats; MAO-A activity was higher only in hypothalamus and medulla of LHST. The same brain regions of LHST rats had higher concentrations of carbonylated proteins and lipid peroxidation products than in SHST rats. MAO activity was correlated with microsomal oxidation phenotype. Rats with higher hepatic content of CYP had higher activities of MAO-A and MAO-B in the brain and higher plasma serotonin levels than rats with lower microsomal oxidation. In conclusion, data obtained in this study showed a correlation between MAO activity and microsomal oxidation phenotype.

Methods of intensifying the anaerobic microbial decomposition of the organic fraction of municipal solid waste (MSW) on an MSW landfill and in anaerobic reactors were studied. It was discovered that it is preferable for the initiation and stabilization of the process of anaerobic digestion of organic waste in laboratory bioreactors at 20 and 50 degrees C to use a mixture of activated suspension of soil from the anaerobic zone of the landfill and digested sewage sludge. Stimulation of methanogenesis was shown in field conditions when digested sewage sludge was added directly into the upper layer of anaerobic zone of the landfill. The investigation of methane production during fermentation of concentrated food waste with a mixture of excessive activated sludge in the laboratory under thermophilic conditions (50 degrees C) has shown that the main problem at the first stage of the process was the acidification of the digested mixture due to the accumulation of volatile fatty acids. It was shown that for stable operation of the bioreactor under thermophilic conditions the amount of inoculum added during the start up should be no less than 30%-50%--based on volatile suspended solids. A sharp decrease in the digestion temperature from 50 to 20 degrees C did not cause methanogenesis termination, since the thermophilically fermented biomass contained both thermophilic and mesophilic methanogens.

We studied immediate and delayed effects of hypobaric hypoxic stress experienced by rat pups in the early postnatal period on the digestive system. It was shown that hypoxia leads to remarkable changes in the functioning of the small intestine, as well as liver and kidney, especially in adult animals.

Activities of digestive enzymes (maltase, alkaline phosphatase, amino peptidase M, and glycyl-L-leucine dipeptidase) in small and large intestine, liver, and kidney were studied in rats of different ages kept in normal (8) and low (3) amounts of pups per litter. The low-protein diet for 10 days at once after weaning was found to change the mass of the organs and their digestive enzyme activities in all studied rat groups. The revealed changes were more prominent in rats kept under conditions of breast-overfeeding. In adult animals of this group, distribution of the alkaline phosphatase activity along the small intestine differed from that in control rats. The obtained results seem to confirm the fact that any disturbance of the nutrition quality in early ontogenesis leads to disturbance of the "metabolic programming of enzyme systems" of digestive and non-digestive organs.

Restriction of protein in nutrition of rat pups weaned at different terms has been found to produce changes in activities of digestive enzymes (maltase, alkaline phosphatase, aminopeptidase M, and glycyl-L-leucine dipeptidase) in the small and large intestine both at once after cessation of nutrition with low-protein diet for 10 days and 4 months later. In adult animals after the earlier or later weaning there are observed not only a decrease or increase of the enzyme activities, but also a different type of distribution of the alkaline phosphatase activity along the small intestine, which is more pronounced in the lately weaned rats. Thus, disturbance of metabolic programming of enzyme systems of the small and large intestine due to a change of quality of nutrition in early ontogenesis depends on terms of weaning of animals.

Early and late separation of rat pups from lactating females and combined effects of the terms of separation and low-protein diet are essential for the formation of enzymes (maltase, alkaline phosphatase, aminopeptidase M, and glycyl-L-leucine dipeptidase) in the large and small intestine, liver and kidneys of adult animals. Similarities and differences in the enzyme reactions to early and late weaning and to a combination of untimely weaning and low-protein diet were detected.

It is stated that Livagen (Lys-Glu-Asp-Ala) is a weakly hydrolyzed peptide. Peptide hydrolases of small intestine do not hydrolyze Livagen even to a small extent. Under in vitro conditions Livagen reduces glycil-L-leucinedipeptidase activity in small intestine by 50%. After two weeks of Livagen administration per os in rats the digestive enzymes activity in young animals reduces, while in old animals it increases. It should be mentioned that the activity of enzymes in old rats after Livagen administration in the majority of cases approaches to the level of the activity in young animals of control group.

Virological examinations of blood, urine and saliva in 75 patients with chronic glomerulonephritis (CG) revealed, in 95% of them, herpes-virus infections caused by herpes simplex virus, type 1 (34.4%), herpes simplex virus, type 2 (2.6%) and cytomegalovirus (12%) or mixed infections (46%). The infection rate in the control group of children without renal pathology was reliably lower. A majority of CG patients (94%) had a diagnostically significant level of antiherpetic antibodies, class IgG, which also evidence to chronic herpes-virus infection.

Low protein content in the ration of rat pups during transfer from mixed to definitive nutrition (days 21-30 of life) has a negative impact on digestive function of the small intestine and trophic and barrier functions of the large intestine, liver, and kidneys and increases (sucrase, glycyl-L-leucin dipeptidase) or decreases (alkaline phosphatase, aminopeptidase M, glycyl-L-leucine dipeptidase) enzyme activities in these organs in 6-month-old rats. Protein deficiency during the early ontogeny modulates functioning of the enzyme systems in digestive and non-digestive organs in adult life, which can lead to the development of not only gastrointestinal, but other visceral diseases.

Activity of disaccharidases in various portions of the small intestine markedly increased in 6-month-old offspring of pregnant females feeding a protein-deficient diet. Activities of amino- and dipeptidases decreased in the kidneys, while alkaline phosphatase activity remained practically unchanged. Probably, information about protein restriction in nutrition of pregnant females is stored in the biochemical memory of adult offspring and promotes the development of metabolic disturbances.

Per os administration of Vilon (Lys-Glu) or Epithalon (Ala-Glu-Asp-Gly) to aged Wistar rats for 1 month significantly increased activity of membrane enzymes maltase and alkaline phosphatase in epithelial layer of the small intestine. In addition, Vilon significantly increased activity of cytosolic glycyl-L-leucine dipeptidase in the stromal and seromuscular layers of the small intestine in comparison with the control rats not treated with this agent. These findings suggest improvement of trophic and barrier functions of the small intestine and corroborate the hypothesis on the existence of not only epithelial, but also subepithelial enzymatic barrier supporting the enzyme system in the small intestine, especially in aged animals.

It is shown, that the value of Km for maltase, alkaline phosphatase, aminopeptidase M and glycyl-L-leucinedipeptidase, prepared from the jejunum and ileum of 10-day rat litter in membrane and soluble forms in most cases differed but a little in control animals and the rat litter whose mothers in the period of lactation had a diet with 2.5-fold reduced content of protein, and did not change under action of injected thyroxin and dexamethasone. It may be assumed that in the given experimental conditions each of the investigated digestive hydrolases in membrane and soluble forms represents the same enzyme. In conditions of the protein insufficiency in lactating females diet and under action of exogene hormones, apparently, no significant changes occur in structure of synthesised enzymes.

It has been found for the first time that protein deficit in female's nutrition during prenatal development of the offspring is accompanied by considerable changes in the activity of intestinal digestive enzymes and of the same hydrolases in the colon, liver and kidneys both in early and in late ontogenesis. It seems possible that changes of the small intestine enzyme functions and hydrolytic functions of other digestive and non-digestive organs in result of an unfavorable early "metabolic/nutritional programming" may be crucial in disorders of metabolic processes leading to development of diseases of risk in adult life.

Suboptimal protein nutrition during lactation has a negative impact on the digestive function of the small intestine and trophic barrier functions of the large intestine, liver, and kidneys due to significant enzyme deficiency (disaccharidase, peptidase, alkaline phosphatase) in 6-month-old offspring. Changes in enzyme activity in digestive and nondigestive organs play an important role in metabolic disorders promoting the development of "risk diseases" and reducing lifespan.

Peroral administration of Epithalon (Ala-Glu-Asp-Gly) to male and female Wistar rats aging 3 and 11 months changed activity of enzymes hydrolyzing carbohydrates, proteins, and phosphoric acid esters in various portions of the gastrointestinal tract. The most pronounced activation of enzymes was observed in 11-month-old animals. This effect diminished the differences in enzyme activities between young and old rats (compared to untreated animals). Our results indicate that Epithalon modulates activity of gastrointestinal enzymes during aging.

Peroral administration of Vilon (Lys-Glu) to male and female Wistar rats aging 3 and 11 months changed activity of digestive enzymes (invertase, maltase, alkaline phosphatase, and amino- and dipeptidases) in various portions of the gastrointestinal tract. The increase in enzyme activity was most pronounced in 11-month-old animals, which diminished differences between rats of various ages. Our results indicate that Vilon produces positive effects on digestive enzyme activity during aging.

In the colon mucous membrane, activity of a wide range of membrane and mainly intracellular enzymes was studied in the organism at different conditions. The data obtained suggest participation of digestive hydrolases in the colon not only on postdigestive processes but, in certain states of the organism, in digestive processes too.

Reviews modern data on laboratory diagnosis (virological, immunobiochemical, molecular biological methods) and differential diagnosis of herpesvirus infection induced by various Herpesviridae.

Protein deficiency in female rats diet during pregnancy and lactation resulted in deceleration of induction of sucrase both forms in the jejunum and ileum; in acceleration of induction of the maltase membrane from in the jejunum; and in suppression of the lactase membrane form in the ileum; in earlier forming of the adult-type distribution of activity of the membrane form of intestinal alkaline phosphatase and in a decrease in activity of the enzyme soluble form. The findings are corroborated by a suppression of activities of the membrane and soluble forms of the small intestine digestive enzymes in 30-day old rat pups fed with a control (adequate) ration starting 21 days after the birth.

With ageing the membrane/soluble form ratio of membrane-boundenzymes increases especially in the ileum and that of peptidases changes rather insignificantly in both portions of the rat small intestine. The soluble forms are supposed to take part in assimilation of food substrates penetrating enterocytes in an unsplit form due to an enhanced permeability of the membranes, particularly those of the ileum.

The effects of sodium nitrate on the activity of digestive enzymes in mucosal and submucosal layers of the small intestine as well as in liver and kidney were studied in the growing rats maintained on either standard or protein-free diets. The enzyme systems were more sensitive in the growing rats to protein deprivation than in adult animals. However, the digestive enzymes were more resistant against nitrate intoxication in the growing rats.

At different times after the transposition of the jejunum and ileum of rats bidirectional changes in the mass and activity of digestive enzymes were observed not only in the epithelial but also in the subepithelial layers of various parts of the small intestine and in the duodenal mucosa. The greatest increase in the mucosal mass was revealed in the duodenum. The activity of membrane enzymes changed insignificantly in the epithelial and subepithelial layers. The activity of cytosolic peptidases was increased to the greatest extent in the subepithelial layers of the small intestine, especially at the early terms after surgical interventions. It is concluded, that the enzyme systems (particularly, peptidase) of the subepithelial layers of the small intestine are an integral part of the enzymatic barrier and perform an important protective function.