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Biomedical subjects

R I Kushak

Publications and source records attributed to R I Kushak.

14 recordsLinked to original sources
PubMed1989

[The effect of sodium ions on amino acid and peptide assimilation in the small intestine of developing chicks].

The absorption of free glycine and L-tryptophan as well as amino acids released in the hydrolysis of glycil-L-leucine and glycil-L-tryptophan was studied in vitro with accumulating preparations of intestinal mucosa of 1-65-day old chicken. Two ways of absorption of free and peptide amino acids were found: sodium-dependent and sodium-independent. Intensity of each of them depended on the age of chicken and was dissimilar for the compounds. The sodium-independent way is more important for glycine than for free amino acid. Absorption of glycil-L-tryptophan as well as its amino acids is mainly performed by the sodium-dependent way.

Aging↗
PubMed1986

[Various routes of L-tryptophan transport in the small intestine of the chick].

Presence of two mechanisms in the accumulation of L-tryptophan by the mucosal cells of chicken small intestine was determined in vitro: sodium-independent and sodium-dependent those, the latter being of a major importance. Analysis of the accumulation kinetics in the linear stage showed that at the replacement of sodium with potassium ions in the incubation medium, a decrease of Kt (from 4.44 mM to 1.05 mM) as well as V (from 0.78 mM/min/cm to 0.12 mM/min/cm) occurs. High level of L-threonine, L-alpha-alanine, L-valine (100 mM) considerably inhibit the accumulation of L-tryptophan from 0.24 or 2.40 mM solution, the highest inhibition (78-96%) being related to the sodium-dependent transport mechanism. No considerable changes in Kt (4.0 mM) were observed in the saturated stage of transport whereas V showed a rapid decrease (0.22 mM/min/cm). Adding of modifier 0.64 mM L-alpha-alanine was followed by the increase both in Kt (5.71 mM) and V (0.37 mM/min/cm).

Alanine↗
PubMed1986

[Membrane digestion and absorption in the bird].

Characteristics of membrane digestion in birds as well as its role in splitting up carbohydrates and proteins revealed the regulatory character of membrane digestion enzymes, their linkage to the enterocyte membrane, dependence on the age and the topography of the small intestine. The systems of active and exchange transport as well as its energetics are described. A close connection between membrane hydrolysis and absorption is shown as actualized by specialized digestive-transport complexes functioning in the enterocyte membrane. Fast and slow adaptation of membrane digestion and absorption are described as well as the ability of parasubstrate regulation of these systems.

Adaptation, Physiological↗
PubMed1986

[Assimilation of free and peptide glycine in the chick small intestine].

Absorption of free and peptide glycine released at the hydrolysis of glycyl-L-leucine, L-leucyl-glycine, glycyl-L-valine was investigated in experiments in vitro with accumulating mucosal preparations of the chick small intestine. An active accumulation of free amino acid occurred in the mucosa depending on sodium and oxygen presence in the incubation medium. The participation of sodium-dependent and sodium-independent components in the transport was revealed. Absorption of peptide glycine released at the hydrolysis of glycyl-L-leucine and glycyl-L-valine appeared to be a sodium-independent process and demanded the energy of aerobic metabolism. The data indicate the effect of various amino acids on the transport of free and peptide glycine. Activating effect of some of them on the absorption of glycine is supposed to be determined for this amino acid by a mechanism of exchange transport in the chick small intestine.

Amino Acids↗
PubMed1983

[Peptide interactions in the intestines of birds].

Interaction among various dipeptides was studied during their uptake in the mucosa of the small intestine of chicks. The effects observed were either inhibiting (L-valyl-L-valine inhibited the uptake of glycyl-L-alpha-alanine, glycyl-L-proline, L-leucyl-glycine, glycylglycine, and L-alpha-alanyl-L-alpha-alanine inhibited the uptake of glycyl-L-proline and L-leucylglycine) or stimulating (L-valyl-L-valine activated the uptake of glycyl-L-leucine), or neutral (L-alpha-alanyl-L-alpha-alanine exerted no significant effect on the absorption of glycyl-L-leucine and glycyl-L-valine). The amount and direction of the modifying effect depended on the agent concentration. Effects observed during the interaction of dipeptides and mixtures of free amino acids equimolar to them were identical. It is only possible if hydrolytic processes precede the transport and are closely related to them.

Amino Acids↗
PubMed1978

[Peptide transport and peptidase localization in the small intestine of chickens].

The mechanism of peptide transport was studied in vitro in the small intestine of chicks and accumulating preparations of mucosa using glycyl-1-tryptophan. A special criterion was proposed to differentiate the processes of intracellular and membrane hydrolysis of dipeptide basing on the analysis of transport intensity of amino acids released into the serosal solution after hydrolysis of dipeptide. 1-tryptophan released at hydrolysis was transported considerably more slowly than free amino acid. 1-tryptophan from the mixture with glycyne demonstrated the highest transport intensity in serosal solution as well as the highest accumulation in the mucosa cells from all forms of 1-tryptophan. At the same time the peptide form of glycyne was transported with the same intensity as that from the mixture with 1-tryptophan. According to the criterion applied it is supposed that unequal levels of 1-tryptophan and glycyne in the serosal solution prove the membrane hydrolysis of glycyne-1-tryptophan during ist transport in enterocytes.

Animals↗
PubMedDate not supplied

[Hydrolysis and absorption of lysozyme in the small intestine].

Preparations of chicken small intestine were used in the experiment in vitro simulating processes of membranous digestion (inverted intestinal segments) and absorption (inverted intestinal myasis). It was established that lysozyme was hydrolyzed on the internal mucosa surface regardless of its concentration in the gastro-intestinal tract, and only insignificant quantity of lysozyme (0.027%) penetrates the intestinal wall. The method of lysozyme determination through its action on the cellular wall of Micrococcus lisodeicticus, and highly efficient liquid chromatography were used to study the transport process. The data presented have evidenced that lysozyme is well hydrolyzed under the action of intestinal peptide hydrolyses, and only insignificant amounts of non-splitted lysozyme can penetrate the blood.

Animals↗
PubMedDate not supplied

[Intestinal dipeptidases and their regulation in chicks of different ages].

Studies have been made of changes in catalytic activity and regulatory properties of membrane and intracellular glycyl-valine dipeptidase from the small intestine of chicks ageing from 1 to 40 days. Gradual decrease in the activity of membrane glycyl-valine dipeptidase was found during postnatal life together with formation of proximodistal gradient in the distribution along the intestine with maximal activity in the distal part. The magnitude and direction of regulatory effects of modificators (tributyrine, sucrose, L-methionine) depend on the age of chicks. Intracellular enzyme does not undergo any significant changes in its regulatory properties and in the level of its activity along the intestine during postnatal development of chicks.

Aging↗