Origination of stromal precursor cells replenishing the population of these cells in heterotopic mouse bone marrow transplants after curettage in recipients.

Curettage of bone marrow cavities of two bones (femoral and crural) in recipient mice causes a drastic (more than 7-fold) increase in the count of stromal precursor cells in heterotopic bone marrow transplants. Stromal colonies in cell cultures from these transplants consist of fibroblasts with an appreciable admixture of macrophages. All y chromosome-typed colonies from cultures of female donor bone marrow transplants in recipient males (intact and subjected to curettage) contained cells carrying and not carrying y chromosome. Quantitative results of Y chromosome typing of cells from colonies corresponded to the fibroblast/macrophage ratio in colonies and the predominant localization of the label corresponded to predominant localization of macrophages (at the periphery of colonies). The results indicate that the pool of bone marrow stromal precursor cells under conditions of increased demands originates from local sources, which confirms ample data on inability of these cells to migration.

[Effect of peptide Livagen on activity of digestive enzymes in gastrointestinal tract and non-digestive organs in rats of different ages].

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.

Effect of Vilon and Epithalon on glucose and glycine absorption in various regions of small intestine in aged rats.

Vilon (Lys-Glu) and Epithalon (Ala-Glu-Asp-Gly) administered orally for 1 month improved transport characteristics of the small intestine in aged rats. Vilon enhanced passive glucose accumulation in the serous fluid in inverted sac made from the distal region of the small intestine, while Epithalon enhanced this process in the medial region. Vilon stimulated active glucose accumulation in the serous sac of the medial small intestine, Epithalon - in the proximal and distal small intestinal segments. Glycine absorption increased only in the proximal intestinal segment under the effect of Epithalon.

[Comparison of cytogenetic response of human lymphocytes to in vivo and in vitro exposure to low-dose gamma rays. Translocations and dicentrics detected by the FISH technique]. / Sravnenie tsitogeneticheskoi reaktsii limfotsitov cheloveka na obluchenie v malykh dozakh gamma-izlucheniia in vivo i in vitro. Translokatsii i ditsentriki, opredeliaemye FISH-metodom.

On peripheral lymphocytes of 5 cancer patients undergone wholebody therapeutic irradiation (at daily dose of 10 cGy up to total dose 50 cGy of 60Co gamma-rays) the dose response of unstable and stable chromosomal exchanges detected by FISH was compared with the dose response of the some aberrations in lymphocytes irradiated in vitro. The dose response fitted well to linear function. For dicentrics the lower slope of dose-response curve was found for in vivo irradiated lymphocytes as compared to the dose-response curve obtained for in vitro irradiated lymphocytes of the same patients. No difference between in vivo and in vitro irradiation of lymphocytes was found for translocations. The frequency of translocations increased faster with the dose than the frequency of dicentrics only in lymphocytes irradiated in vivo.

[The current concepts on the absorption of monosaccharides, amino acids and peptides in the mammalian small intestine]. / Sovremennye predstavleniia o vsasyvanii monosakharidov, aminokislot i peptidov v tonkoi kishke mlekopitaiushchikh.

The review is mainly devoted to the development of ideas about absorption, or transport, of basic nutrients in the small intestine in humans and higher animal. The absorption processes have been characterized on the example of such substances, vital for organism, as carbohydrates and proteins. The review considers a molecular structure of transporters--protein molecules, which take part in a transfer of the products of lumenal and membrane digestion of carbohydrates (glucose, galactose, fructose) and proteins (amino acids, oligopeptides) across the enterocyte membranes. An information is presented about genetic disturbances of transport of certain amino acids during such diseases as Hartnup disease, cystinuria, and iminoglycineuria.

[Effect of age and radiation exposure on the frequency of translocations and dicentrics detected by FISH method in human lymphocytes]. / Vliianie vozrasta i oblucheniia na chastotu translokatsii i ditsentrikov, opredeliaemykh metodom FISH, v limfotsitakh cheloveka.

The frequencies of translocations and dicentrics detected by "chromosome painting" in lymphocytes were estimated in 115 healthy donors and in 273 people exposed to uncontrolled irradiation at low doses 1-4 years ago. Age responses of both types of exchanges at the age range from 3 to 85 years fit to quadratic model. The frequency of translocations grew faster with age than the frequency of dicentrics. The yields of stable exchanges in exposed people was significantly higher than those in control donors of corresponding ages.

[Comparison of cytogenic response of human lymphocytes to in vivo and in vitro exposure to low doses of gamma-rays. Unstable chromosomal exchanges detected by FPG techniques]. / Sravnenie tsitogeneticheskoi reaktsii limfotsitov cheloveka na obluchenie v malykh dozakh gamma-izlucheniia in vivo i in vitro. Nestabil'nye khromosomnye obmeny, opredeliaemye FPG-metodom.

On peripheral lymphocytes of eight cancer patients undergone whole-body therapeutic irradiation (at daily dose of 10 cGy up to total dose of 50 cGy of 60Co gamma-rays) the dose-response of unstable chromosome exchanges (dicentrics and centric rings) was studied. This dose response fitted well linear function. The lower slope of dose-response curve was found for in vivo irradiated lymphocytes as compared to the dose response curve obtained for in vitro irradiated lymphocytes of the same patients. This finding seems to provide evidence that in case of protracted irradiation of individuals an absorbed dose could be underestimated if for biological dosimetry an in vitro dose response curve for unstable chromosome aberrations is used as referent one.

[Digestive enzyme activity in growing rats consuming nitrates against a background og protein insufficiency]. / Aktivnost' pishchevaritel'nykh fermentov u rastushchikh krys pri potreblenii imi nitratov na fone belkovoi nedostatochnosti.

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.

[The effect of sodium nitrate on the digestive enzyme activity of the small intestine, liver and kidneys of rats]. / Vliianie nitrata natriia na aktivnost' pishchevaritel' fermentov tonkoi kishki, pecheni i pochek krys.

The activity of digestive enzymes was reduced both in the small intestine mucosal layer and in the postepithelial ones. The reduction was due to sodium nitrate administration and was more obvious in the rats fed with proteins. The response of the enzyme systems of the liver and kidney was heterogeneous.

Localization of peptide hydrolysis in the enterocyte and the transport mechanisms of apical membrane.

1. The absence of the effect of anoxia on the hydrolysis rate of a number of dipeptides and one tripeptide by the intact and homogenized mucosa of the small intestine in different mammals (rat, mouse and guinea pig) has been demonstrated. 2. It has been shown that in rats anoxia inhibits intestinal transport both of free glycine and glycine formed during the hydrolysis of Gly-Leu, Leu-Gly, Gly-Pro but not Pro-Gly. 3. Data obtained using the anoxic criterion suggest that the systems of membrane hydrolysis of peptides with the subsequent absorption of released amino acids presents a dominant mechanism of protein assimilation under normal physiological conditions. 4. However, they do not exclude the possibility of the transport of peptides across the apical membrane of enterocytes.

Membrane and intracellular hydrolysis of peptides: differentiation, role and interrelations with transport.

The possible relative importance of the membrane and intracellular peptidases of the enterocytes in splitting dietary peptides to amino acids has been analysed. On the anoxic criterion, membrane hydrolysis was found to be predominant. Model experiments revealed cooperative interactions between the membrane enzyme and the coupled transport system. This cooperativity allows the main characteristics of oligomer transport to be described in terms of membrane digestion. Comparison of the behaviour of membrane and intracellular peptidase under different conditions has shown that the former are largely involved in digestion and the latter in intracellular metabolism. It is suggested that the efficiency of the membrane system is high enough to account for the hydrolysis of protein, especially taking into account the stimulation of enzyme processes in the brush border that occurs after ingestion of protein and carbohydrate. A sequential model based on the concept of three interacting enzyme layers (glycocalyx, lipoprotein membrane and cytosol) is presented.