Mechanisms of the changes in the rate and nature of reparative regeneration of the aortic endothelium after repeated injuries

An experimental model of repeated cryogenic lesions in the rat abdominal aorta endothelium with a concentrically decreasing area of the defect has been worked out. In reendothelization of every successive defect participate the cells of the endothelial layer that is formed anew after the preceding lesions. As a result of repeated lesions the regeneration rate increases by 1.2 times. By means of scanning radioautography after 3H-thymidine++ administration the index of the labelled nuclei of the endothelial cells (EC) has been demonstrated to increase by 2.2 times. In the experiments with gamma-irradiation of the vessel before the last cryodestruction (this results in blockade of proliferation) an increased rate of EC migration has been revealed. Repeated lesions also produce an increase in the heteromorphism degree of the endothelial layer. This is mainly manifested as appearance of multinuclear EC clusters. These changes in rate and in character of the endothelium regeneration can be determined by the mechanisms similar to clonal proliferative senescence of EC in vitro.     

State of the endothelium of the aorta during chronic stress

In 50 white male rats (18-control and 32-experimental) using morphometrical and stereological methods for film preparations of endothelium, the state of the internal aortal lining at various stages of chronic stress developing during muscular activity has been studied. The data obtained are statistically treated by the sliding averages method, reliability of the differences is estimated according to the value of nonparametrical criterion of Wilcoxon-Mann-Whitney. For objective periodization of the endothelial reaction to stress, centered moving averages curves are performed with subsequent calculation of the coefficient of variation for the aligned ordinates of the approximated values in every temporal point. The aortal endothelium reaction to the stress is of phasic character. During the alarm reaction, destructive changes predominate; they are accompanied with an increased mitotic activity of endotheliocytes up to 2.2%. The resistance stage increases compensatory-adaptive rearrangements, which are manifested not only as cellular hyperplasia, but as hyperthrophy of nuclei, increasing number of strangulated nuclei, nucleoli, as well as binuclear and trinucler cells. To the exhaustion period the increase of alternative and restorative transformations of the tissue corresponds.     

The relation of the typological classification of dogs to their behavioral characteristics in variations between the probability and the value of reinforcement]

In studying of dogs behaviour in coordinates system "Requirements and probability of their satisfaction" it has been established that selection of behaviour strategy is closely connected with individual typological properties of animals. In experiments with equally-probable alimentary reinforcement a direct correlation was found between the strength parameter of the nervous system and the strategy of dogs behaviour. Animals of strong types manifested the character of reaction which consisted in determination and goal-directedness, while the animals of the weak type manifested other character, having features of uncertainty, indefinition, hesitations. In conditions of conflict between probability and value of reinforcement the dogs manifested two opposite strategies of behaviour: orientation to highly probable events (choleric and phlegmatic) and to low-probable events (sanguinic and melancholic) what is connected with individual properties of functioning and the character of interaction of four brain structures (frontal cortex, hippocampus, hypothalamus, amygdala).     

Trends in the evolution of dicotyledonous seeds based on character associations, with special reference to pachychalazy and recalcitrance

VON TEICHMAN, I. & VAN WYK, A. E., 1991. Trends in the evolution of dicotyledonous seeds based on character associations, with special reference to pachychalazy and recalcitrance. The possible evolutionary status of the endothelium, hypostase, pachychalaza and the recalcitrant viability behaviour of seeds is considered in relation to bitegmy/unitegmy, crassinucellate/tenuinucellate ovules, nuclear/cellular endosperm development, large/small seed size, woody/herbaceous habit and tropical/temperate habitat. The presence of the endothelium, hypostase, pachychalaza and recalcitrance in dicotyledonous families is plotted against Dahlgren's system of classification. Results are compared with Sporne's advancement index for the various families. An endothelium is considered derived since it occurs more often in highly evolved superorders and is significantly associated with derived ovule and endosperm character states as well as with smaller seed size. A hypostase appears to be relatively ancestral and is significantly associated with pachychalazy and recalcitrance. The endothelium and hypostase have developed independently in many taxa and could be interpreted as being structurally and functionally analogous. Pachychalazy and recalcitrance are significantly associated with ancestral ovule character states and, at the species level, with large seed size (overgrown seed), woody habit and tropical habitat. The presence of pachychalazy, recalcitrance and associated large seed size are therefore regarded as ancestral character states of the dicotyledons. Consideration of currently accepted dicta on seed character state polarity, suggests a reversal in the evolutionary status of pachychalazy and large seed size.     

Analysis of the spatial organization of the endothelium of several major vessels

The aim of the investigation was to appreciate quantitatively the degree of endothelial heteromorphy and its spatial organization according to some indices allowing morphofunctional interpretation of their importance. Endothelium of the rabbit protal and jugular veins was studied in the flat film preparations along the length of 16--20 mm continuously. To elucidate changeability in tissue state, autocorrelative function was calculated with the following determination of spectral density. The latter makes it possible to reveal the presence of a monotonous trend and rhythmicity in vessel structure. Spectral analysis demonstrated that in different parts of endothelium the indices involved varied in their character. The parameters reflecting cell histophysiology are characterized by a marked monotonous trend. The parameters influenced by hemodynamic conditions change rhythmically. Nearly all the indices in the portal vein, evidently because of its peculiar physiological conditions, distinguish themselves by their more complex spectral composition than those of the jugular vein. The quantitative data obtained support heteromorphic character of endothelium and demonstrate that physiology and hemodynamics of the vessel are responsible for its degree of significance as there is a constant interrelation between the vessel and blood.     

Ultrastructure of sensorimotor cortex neurons in the progeny of rats receiving alcohol during pregnancy

Dynamics of ultrastructural changes in the sensomotor cortex neurons has been studied on the 21st, 30th and 60th days of life in offspring born by the rats given 20% alcohol (2 g/kg) during pregnancy. Moderate antenatal alcoholization produces certain disturbances in the ultrastructure of the cortical neurons and their dendrites. This is manifested as presence of retardation signs in maturation of nervous cell populations, as dystrophic changes in the neurons and their dendrites and display of reparative character with their own dynamics in the postnatal period of ontogenesis. The first two categories of the ultrastructural changes in the cortical neurons are more manifested at early stages of the postnatal development of the offspring, and the reparative processes--at the age of two months. Despite the presence of the reparative shifts, the dystrophic changes of the neurons of hypoxic character are present up to the period of sexual maturation. This demonstrates that the antenatal alcoholic intoxication in the offspring is manifested in the postnatal ontogenesis for a long time.     

The histologists of the S. M. Kirov Military Medical Academy--their contribution to practical medicine]

This is a short review of investigations of an applied character, performed at the Department of Histology and Embryology of the Academy. Most of the investigations have been carried out as joint works with clinicians and are aimed to solve some actual tasks of practical medicine. Their main contents have been investigations on reactivity and degeneration of tissues under various experimental and clinical conditions. Some new data have been obtained concerning cellular and ultrastructural mechanisms of the wound process, scientifically grounded influences have been undertaken in order to regulate this process. The material presented has served as a base for elaboration of a number of fundamental principles of histology and first of all some new ideas on histogenesis, cellular-differon organization and reparative regeneration of tissues. Regularities of histo- and organogenesis and intertissue interrelation are the base for understanding regeneration mechanisms of organs and tissues. In what form the reparative regeneration is manifested depends on histogenesis and is specific for each tissue. To know regularities of histogenesis and peculiarities of its manifestation is necessary to understand problems of pathology, since regularities of the normal histogenesis serve as a foundation for understanding the essence of pathological processes.     

Effect of acetylcholine on the structuro-functional characteristics of bush-like interoceptors of the urinary bladder of the frog

In the preparation of the frog (Rana temporaria) isolated urinary bladder, it has been stated by morphological and physiological experiments that under an exogenic acetilcholine influence certain structural-functional changes take place in the bushy interoceptor. They are manifested as a sharp deterioration in coloration the receptor with methylene blue, the receptory plates decrease in their size, character of granuloformation changes in them. Simultaneously, an increased electrical activity is observed and, on the contrary, under the influence of atropine the impulse activity drops. It should be suggested that acetilcholine acts as an activator of metabolic and as a modulator of physiological processes in the receptor.     

The use of DNA fingerprint analysis for the differentiation of populations of toxigenic Corynebacterium diphtheriae

13 C. diphtheriae strains were used as a model to establish the conditions of making the fingerprint analysis of chromosomal DNA. These strains, subdivided into 7 groups in accordance with the character of their restriction splitting, were mostly isolated from territorially close sources and belonged to the same phagotype. Probably, C. diphtheriae DNA has strain variations manifested by an unequal number and location of the sites of the recognition of specific endonucleases, which may be used for the intraspecific differentiation of C. diphtheriae.     

The structure and function of the blood-brain barrier

It is now clear that the phenomenon of a blood-brain barrier results from the high-resistance endothelium of cerebral vessels. The glial sheath appears to have no transport function but determines the specific characteristics of the cerebral endothelium. Among the transport mechanisms present in the endothelium is a potent sodium-potassium pump in the abluminal membrane. The endothelium probably secretes a small volume of fluid into the cerebral interstitium. Ouabain-insensitive potassium transport has been investigated in isolated cerebral capillaries. This component is very dependent on the osmolality of the medium, being markedly increased in a hypertonic medium and decreased in hypotonic conditions. This behavior may well be important in determining the net exchanges of potassium across the blood-brain barrier, which contribute to volume control of the brain in osmotic disturbances.     

The formation of a test system for assessing the safety of different types of pertussis preparations: their cytotoxic action on mouse thymocytes in vitro

The test for the evaluation of the toxicity of different types of pertussis preparations as manifested by their in vitro influence on mouse thymic cells (T test) has been finally worked out. The use of the T test has made it possible to reveal the nonstandard character of the production lots of adsorbed diphtheria-pertussis-tetanus vaccines, both whole-cell vaccine and Japanese acellular vaccine. The degree of the in vitro damaging action of pertussis preparations on mouse thymic cells greatly depends on the residual content of Bordetella pertussis nontoxoidized toxin which, in contrast to B. pertussis lipopolysaccharide and filamentous hemagglutinin, produces pronounced cytotoxic action on mouse thymic cells.     

Novel strategy for selection of monoclonal antibodies against highly conserved antigens: phage library panning against ephrin-B2 displayed on yeast

Ephrin-B2 is predominately expressed in endothelium of arterial origin, involved in developmental angiogenesis and neovasculature formation through its interaction with EphB4. Despite its importance in physiology and pathological conditions, it has been challenging to produce monoclonal antibodies against ephrin-B2 due to its high conservation in sequence throughout human and rodents. Using a novel approach for antibody selection by panning a phage library of human antibody against antigens displayed in yeast, we have isolated high affinity antibodies against ephrin-B2. The function of one high affinity binder (named as 'EC8') was manifested in its ability to inhibit ephrin-B2 interaction with EphB4, to cross-react with murine ephrin-B2, and to induce internalization into ephrin-B2 expressing cells. EC8 was also compatible with immunoprecipitation and detection of ephrin-B2 expression in the tissue after standard chemical fixation procedure. Consistent with previous reports on ephrin-B2 induction in some epithelial tumors and tumor-associated vasculatures, EC8 specifically detected ephrin-B2 in tumors as well as the vasculature within and outside of the tumors. We envision that monoclonal antibody developed in this study may be used as a reagent to probe ephrin-B2 distribution in normal as well as in pathological conditions and to antagonize ephrin-B2 interaction with EphB4 for basic science and therapeutic applications.     

A triphasic analysis of corneal swelling and hydration control.

Physiological studies strongly support the view that hydration control in the cornea is dependent on active ion transport at the corneal endothelium. However, the mechanism by which endothelial ion transport regulates corneal thickness has not been elaborated in detail. In this study, the corneal stroma is modeled as a triphasic material under steady-state conditions. An ion flux boundary condition is developed to represent active transport at the endothelium. The equations are solved in cylindrical coordinates for confined compression and in spherical coordinates to represent an intact cornea. The model provides a mechanism by which active ion transport at the endothelium regulates corneal hydration and provides a basis for explaining the origin of the "imbibition pressure" and stromal "swelling pressure." The model encapsulates the Donnan view of corneal swelling as well as the "pump-leak hypothesis."     

The effect of the cationic proteins of human blood cells on the growth of Escherichia coli

The antibacterial effect of cationic proteins (CP) on donor leukocytes and thrombocytes with respect to the growth of E. coli has been demonstrated in vitro, the maximum recorded inhibition being caused by the action of leukocytic CP. Differences in the inhibitory action may be linked with the presence of anomalies in the amino acid composition of leukocytic CP and thrombocytic CP, manifested by the deterioration of the basic properties of the latter, as well as by the fractional composition whose characteristic features for thrombocytic CP are the appearance of high-molecular components and a decrease in the proportion of low-molecular fractions. In patients with different forms of leukosis (chronic myeloleukemia, chronic lympholeukemia, acute myelomonoblastic leukosis) leukocytic CP retain their antibacterial activity. Under the action of blood cell CP changes in the outer and cytoplasmic membranes have been noted.     

Regulation of smooth muscles of the vascular wall in the rabbit pulmonary artery

The cholinergic, histaminergic and adrenergic features of regulation of the small muscles contractile activity in a vascular wall of a pulmonary artery in rabbits and involvement of an endothelium in these processes, were investigated. The cholinergic release phenomenon of small muscles of the rabbit pulmonary artery has a two-component character of dose dependence. The low-threshold components of Pilocarpinum relaxing effect has an endothelium-dependent nature. The important feature of histaminergic regulation of contractile activity of segments involves a direct contractile effect of histamine that is not inherent. The endothelium renders a suppressing effect on histaminergic contraction of small muscles of the rabbit pulmonary artery. A basic feature of adrenergic regulation of the pulmonary artery involves registered-beta-adrenergic contractile effects in small muscles of a vascular wall. The activation of the cAMP-dependent signal system in small muscles of a pulmonary artery is capable of rendering a contractile effect. The detected features of a regulation in the small circle can have an essential clinical-physiological value.     

Changes in the femur of fur-bearing animals during hypodynamia

Under conditions of hypodynamia the form and internal architectonics of the femoral bone undergo certain changes. In young animals these changes are of quantitative character without any signs of a manifested destruction. Later on, certain indications of focal resorption appear in the spongy substance, as does partial destruction of the beams. Gradually, definite signs of osteoporosis and osteosclerosis as a result of dystrophic alterations in the osseous tissue develop. These phenomena, though progress with age, nevertheless, develop against the background of noticeable compensatory shifts in the osseous structures: increment in the mass of some osseous beams, appearance of new strengthening osseous plates in the spongiosa. The symptom complex at adaptational rearrangement of the bone under hypodynamia should be taken into account at differential diagnosis of these conditions both in the clinic and at experimental modelling.     

Nature of the restructuring of the T- and B-immunity systems in patients with cutaneous and visceral candidiasis

The examination of 90 patients with superficial and visceral candidiasis, as well as Candida carriers, has revealed that the heavy contamination of the body with fungi of the genus Candida is accompanied by the specific transformation of the immune system, manifested by differences in the character of sensitization to Candida antigens: in the patients with superficial and visceral candidiasis the B-system of immunity is sensitized to a greater degree, while in the Candida carriers the sensitization of the T-system is more pronounced. Despite the fact that the immune system of patients with the disseminated form of visceral candidiasis is capable of developing the delayed hypersensitivity (DH) reaction to bacterial allergens, such patients have been shown to develop DH to Candida antigens only in rare cases. This is probably due to disturbances in their immunocompetent systems, caused, seemingly, by the secondary immune insufficiency.     

Yersinia pseudotuberculosis plasmids and their significance in the realization of the epidemic process in pseudotuberculosis

The results obtained in the electrophoretic study of the plasmid spectra of 190 Y. pseudotuberculosis strains, isolated from different sources, in 0.6% agarose gel are presented. 11 types of plasmids differing in their molecular weight have been detected. Plasmids with a molecular weight of 45 MD determine Ca2+ dependence, bacterial virulence for white mice and autoagglutination. The presence of differences in Y. pseudotuberculosis strains of serovars I, III and IV has been established, which is manifested by their differing plasmid spectra. The relationship between the presence of plasmids with a molecular weight of 75 and 45 DM in the strains and the character of pseudotuberculosis morbidity in the population has been demonstrated. The epidemic course of infection correlates with the presence of both these plasmids and the sporadic course of infection, with the presence of the plasmid with a molecular weight of 45 MD only.     

Endothelial reparative regeneration--a self-regulating process?

When investigating dynamics of reparative regeneration of the rat aorta endothelium after injuring a considerable area by means of cryogenic lesion, a certain tendency to cluster arrangement of proliferating endothelial cells (EC) has been revealed at the edge of the defect both at the beginning and at the end of the reparative process. This fact together with the data on mechanisms of migration and proliferation of EC makes it possible to suppose certain scheme of the mitotic reaction development in endothelium. It consists of centropetal movement of waves of interdependent acts of contraction and flattening of endotheliocytes. Some characteristics of the regenerative proliferation of endothelium make it possible to formulate a hypothesis on autowave character of its regulation.     

Microfluidic Endothelium for Studying the Intravascular Adhesion of Metastatic Breast Cancer Cells

Background

The ability to properly model intravascular steps in metastasis is essential in identifying key physical, cellular, and molecular determinants that can be targeted therapeutically to prevent metastatic disease. Research on the vascular microenvironment has been hindered by challenges in studying this compartment in metastasis under conditions that reproduce in vivo physiology while allowing facile experimental manipulation.

Methodology/Principal Findings

We present a microfluidic vasculature system to model interactions between circulating breast cancer cells with microvascular endothelium at potential sites of metastasis. The microfluidic vasculature produces spatially-restricted stimulation from the basal side of the endothelium that models both organ-specific localization and polarization of chemokines and many other signaling molecules under variable flow conditions. We used this microfluidic system to produce site-specific stimulation of microvascular endothelium with CXCL12, a chemokine strongly implicated in metastasis.

Conclusions/Significance

When added from the basal side, CXCL12 acts through receptor CXCR4 on endothelium to promote adhesion of circulating breast cancer cells, independent of CXCL12 receptors CXCR4 or CXCR7 on tumor cells. These studies suggest that targeting CXCL12-CXCR4 signaling in endothelium may limit metastases in breast and other cancers and highlight the unique capabilities of our microfluidic device to advance studies of the intravascular microenvironment in metastasis.