P6482Stress echocardiography in the assessment of long-term outcomes results of aortic valve replacement with mechanical prostheses of small size

Relevance

Evaluation of the function of aortic mechanical prostheses of small size in the long-term period is an topical problem, due to the fact that a narrow fibrous ring occurs in 20–35% of cases of patients with aortic stenosis.

Objective

To study clinical and hemodynamic parameters of small size aortic prostheses using stress echocardiography in the long-term period after valve replacement

Materials and methods

The study included 89 patients (54 women, 35 men) who underwent aortic valve replacement with a landing diameter of 21 mm or less.

The average was 48,1±11,3 years. BSA of 1,8 m2 (1.3 to 2.2). The following models of prostheses were used: On-X, ATS-AP, Carbomedics, St. Jude Medical. All patients after surgical correction in the long-term period (an average of 5,9±3,3 years from 1 to 11 years) underwent a comprehensive clinical and instrumental examination, including an ECG and stress - echocardiography with bicycle exercise.

Results

In the long-term period after aortic valve replacement of mechanical prostheses of small size, the ECG showed regression of hypertrophy and overload of the left ventricle.

According to stress-echocardiography, there was a significant increase in load tolerance. At the peak of the load, the following were recorded: improvement of the pumping function and cardiac performance (stroke volume, cardiac output, cardiac index), improvement of myocardial work index (Tei - index), increase in speed parameters on the aortic valve prosthesis no more than 30% of the initial values.

In repose, the maximum and mean pressure gradients were 26.3±9 mm Hg and 14.3±5.4 mm Hg, effective orifice area (EOA) 1,7±0,3 cm2, index effective orifice area (EOAi) 0,93±0,2 cm2/m2. When the submaximal load levels were reached, the maximum and mean pressure gradients were 33,5±6,0 mm Hg and 17,1±4,0 mm Hg, EOA - 1,5±0,4 cm2, EOAi - 0,79±0,6 cm2/m2.

Conclusions

The findings suggest that modern models of aortic prostheses with an increased effective orifice area provide good clinical results in the long term. Stress echocardiography is a necessary and highly informative method for assessing the parameters of mechanical aortic prostheses and heart function.

[Evolution of mitral valve replacement]

Historical development of mitral valve surgery at Petrovsky Russian Research Center for Surgery is described in the article. Evolution of artificial heart valves design and development of surgical techniques are presented.

Role of the low-selective organic anion transport in regulation of osmotic balance of renal collecting duct principal cells under hypo-osmotic conditions

In the course of adaptation of the rat kidney collecting duct cells to hypo-osmotic medium, the organic anion transporter inhibitor probenecid reduced significantly the regulatory cell volume decrease in response to a hypotonic shock. Both probenecid and hypotonic shock delayed significantly the entry into a cell of the fluorescent dye calcein, which exists as anion at neutral pH. Thus, the organic osmolyte transport plays an important role in the regulatory decrease of the principal cell volume under the hypo-osmotic conditions.

Endothelial and smooth muscle cells derived from human cardiac explants demonstrate angiogenic potential and suitable for design of cell-containing vascular grafts

Background

Endothelial and smooth muscle cells are considered promising resources for regenerative medicine and cell replacement therapy. It has been shown that both types of cells are heterogeneous depending on the type of vessels and organs in which they are located. Therefore, isolation of endothelial and smooth muscle cells from tissues relevant to the area of research is necessary for the adequate study of specific pathologies. However, sources of specialized human endothelial and smooth muscle cells are limited, and the search for new sources is still relevant. The main goal of our study is to demonstrate that functional endothelial and smooth muscle cells can be obtained from an available source—post-surgically discarded cardiac tissue from the right atrial appendage and right ventricular myocardium.

Methods

Heterogeneous primary cell cultures were enzymatically isolated from cardiac explants and then grown in specific endothelial and smooth muscle growth media on collagen IV-coated surfaces. The population of endothelial cells was further enriched by immunomagnetic sorting for CD31, and the culture thus obtained was characterized by immunocytochemistry, ultrastructural analysis and in vitro functional tests. The angiogenic potency of the cells was examined by injecting them, along with Matrigel, into immunodeficient mice. Cells were also seeded on characterized polycaprolactone/chitosan membranes with subsequent analysis of cell proliferation and function.

Results

Endothelial cells isolated from cardiac explants expressed CD31, VE-cadherin and VEGFR2 and showed typical properties, namely, cytoplasmic Weibel-Palade bodies, metabolism of acetylated low-density lipoproteins, formation of capillary-like structures in Matrigel, and production of extracellular matrix and angiogenic cytokines. Isolated smooth muscle cells expressed extracellular matrix components as well as α-actin and myosin heavy chain. Vascular cells derived from cardiac explants demonstrated the ability to stimulate angiogenesis in vivo. Endothelial cells proliferated most effectively on membranes made of polycaprolactone and chitosan blended in a 25:75 ratio, neutralized by a mixture of alkaline and ethanol. Endothelial and smooth muscle cells retained their functional properties when seeded on the blended membranes.

Conclusions

We established endothelial and smooth muscle cell cultures from human right atrial appendage and right ventricle post-operative explants. The isolated cells revealed angiogenic potential and may be a promising source of patient-specific cells for regenerative medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1156-1) contains supplementary material, which is available to authorized users.

[THE ROLE OF THE PI3-KINASE IN THE FAST NONGENOMIC ALDOSTERONE EFFECTS IN THE PRINCIPAL CELLS OF THE CORTICAL COLLECTING DUCT OF THE RAT KIDNEY IN THE POSTNATAL ONTOGENESIS]

The involvement of wortmannin (10 -5 M), phosphatidyl inositol 3-kinase (PI3K) blocker, in the implementation of the rapid nongenomic aldosterone (10 nM) effects on the intracellular sodium (Na i +) and the principal cell volume of cortical collecting duct (CCD) of 10-day and adult rat kidney CCD was studied. Using fluorescence microscopy with intracellular dye Na Green and Calcein we found that wortmannin weakened the effect of aldosterone on the Na i + at low sodium in the extracellular medium (14 mM NaCl), and slowed the rate of reduction of the principal cell volume in the presence of aldosterone at the hypoosmotic shock (240/140 mOsm) since 10 days of age. The findings suggest the participation of phosphatidylinositol pathway in the fast nongenomic aldosterone effects (seconds and minutes) at the early stage of postnatal ontogenesis.

Regulation of V2 receptor by vasopressin is different in Brattleboro rats compared with Wistar

This paper presents the new priority data on the effect of genetically determined deficiency of endogenous vasopressin on the functioning of V2 receptor in the plasma membrane of the principal cells of the collection ducts of Brattleboro rats. It was found that 2-day desmopressin administration results in the activation of V2 receptor gene expression in Brattleboro rat, whereas in Wistar rats the content of mRNA did not change. In addition, short-term exposure of the collection ducts of the kidneys to the hormone led to V2 receptor internalization from the plasma membrane in Wistar rats, but had no effect on the protein content in Brattleboro rats.

[Features of the immune proteasome expression in ascite Zajdela hepatoma after implantation into Brattleboro rats with the hereditary defect of arginine-vasopressin synthesis]

The expression of the total proteasome pool, immune proteasome subunits LMP2 and LMP7, TAP1 and TAP2 transporters, as well as RT1A molecule of MHC class I was investigated in the ascite Zajdela hepatoma at the 10th day after implantation into Brattleboro rats with the hereditary defect of hypothalamic arginine-vasopressin synthesis (AVP) and into WAG rats with normal AVP expression. In Zajdela hepatoma cells implanted into Brattleboro rats the 3-fold increase of the total proteasome pool and LMP2 level and 8-fold increase of the LMP7 level was detected by Western blotting as compared to those in WAG rats. Differences in the LMP2 and LMP7 expression suggest variations in their functions, namely the important role of LMP7 in anti-tumor immunity. The growth of Zajdela hepatoma in WAG rats was accompanied by the decreased level of total proteasome pool as well as immune proteasome expression as compared to those in Brattleboro rats during the regression of tumor. The analysis of TAP1 and TAP2 revealed the pronounced expression of these peptide transporters in Zajdela hepatoma cells implanted into Brattleboro and WAG rats. The expression level of RT1A molecule of MHC class I was increased 3 times in Zajdela hepatoma cells implanted into Brattleboro rats as compared to WAG rats. Moreover, flow cytometric analysis of CD4- and CD8-lymphocytes number in the spleen of Brattleboro and WAG rats was performed at the 10th day after implantation of Zajdela hepatoma. The increased number of CD4- and CD8-lymphocytes was observed in the spleen of Brattleboro as compared to WAG. The increased subpopulations of cytotoxic T-lymphocytes and T-helpers might promote the tumor regression in Brattleboro rats. The reduced populations of CD4- and CD8-lymphocytes in the spleen of WAG rats were accompanied by the splenomegaly and tumor progression. The data obtained suggest that AVP deficiency in Brattleboro rats leads to the increase of the immune proteasome and MHC class I expression in Zajdela hepatoma cells, resulting in tumor immunogenicity and its elimination by the adaptive immunity.

Role of epithelial sodium channel in the realization of homeostatic effects of aldosterone on the volume of principal cells of cortical collecting ducts in rats after hypoosmotic stress

The mechanism of aldosterone effects (10 nM) on the volume of the principal cells of cortical collecting ducts after hypoosmotic stress (280/140 mOsm/kg) was studied using fluorescence microscopy. The experiments with intracellular fluorescent dye calcein showed that aldosterone significantly decreases the amplitude and rate of increase in principal cell volume during hypoosmotic stress. Epithelial sodium channel blocker amiloride (10(-5)M) significantly attenuated the effects of aldosterone on the amplitude and rate of changes in cell volume. The obtained data attest to the contribution of epithelial sodium channel to the realization of rapid non-genomic effects of aldosterone on the amplitude and rate of changes in volume of the principal cells of cortical collecting ducts in rat kidney after hypoosmotic stress.

[Expression of the RT1A molecule of the class I major histocompatibility complex in a Walker 256 tumor after transplantation into Brattleboro rats with a genetic defect of arginine-vasopressin synthesis]

The dynamics of expression of the RT1A antigen of the class I major histocompatibility complex (MHC) in a Walker 256 tumor after its transplantation into Brattleboro rats with a genetic defect of Arginine-Vasopressin synthesis in the hypothalamus was studied. Expression of the RT1A antigen was detected by means of Western-blotting and flow cytometry in the tumor cells on the 14th-17th days after transplantation. In addition, a simultaneous increase in the portion of cells that express the RT1A antigen and in the level of its expression per cell was observed. It is presupposed that at a deficiency of Arginine-Vasopressin, a renewal of expression of the class I MHC antigens, which results in an increase of immunogenicity of this tumor and regression, occurs in the Walker 256 tumor in the Brattleboro rats.

Effects of sodium diclofenac on the concentration function in animals with different neurohypophyseal status

The characteristics of the osmotic concentration system under conditions of sodium diclofenac treatment were studied in Wistar rats with normally functioning vasopressin gene and homozygotic Brattleboro rats completely lacking endogenous vasopressin. Blockade of prostaglandin synthesis in rats with different neurohypophyseal status stimulated urinary osmolality to a different degree. Different contribution of sodium cations and urea to osmotic concentration was revealed.

[Hyaluronidase activity of Wistar rat blood plasma: effect of dehydration and vasopressin]

Effect of dehydration and arginine vasopressin treatment (Arg-VP Sigma, USA, 50 ng/100 g b.wt. ip.) on the blood plasma hyaluronidase activity in Wistar rats was studied. It was found that the pH optimum of the enzyme activity was in the range of 3.5-3.7 that is characteristic for the hyaluronidase type 1. Water deprivation for 1 day was followed by significant increase in the blood plasma hyaluronidase activity. The same response was observed under vasopressin treatment. The possible role of increased plasma hyaluronidase activity in the regulation of water balance is discussed.

[Expression of the genes Egf and Egfr in renal tissue of the hypertensive rats of the ISIAH strain]

Activation of the epidermal growth factor receptors (EGFR) plays an important role in the regulation of the kidney blood circulation and ion transport. The mRNA content of the epidermal growth factor (Egf) and its receptor (Egfr) genes were studied in the cortical and medullar parts of the kidney of rats with stress sensitive arterial hypertension (ISIAH strain) and normotensive WAG rats. There were no differences in the Egf expression between the rat strains at rest and under emotional stress in both the cortical and medullary kidney zones. As for Egfr transcription, it was significantly higher in the cortical and medullary parts of the ISIAH kidneys at rest as compared to the control WAG. Emotional stress induced no significant changes in the Egfr transcription in the cortical kidney parts of both rat strains. But prominent enhancement of Egfr transcription after emotional stress was observed in the kidney medulla of the WAG rats: it became the same as in the ISIAH rats at rest. It was suggested that the stress hormones might be involved in the regulation of Egfr transcription, and this connection between stress and Egfr gene activity might play a significant role in the kidney involvement in pathogenesis of stress sensitive arterial hypertension.

[Vasopressin: molecular mechanisms of antidiuretic effect]

Body water balance is regulated by vasopressin, and multiple studies now have revealed essential role of aquaporins in this process. This review summarizes recent advances related to molecular events underlying the short-term control of water permeability which occurs via vesicular trafficking of AQP2 to the cell apical membrane, and long-term control through changes in the gene expression and the abundance of AQP-2, -3 and -4. The action of vasopressin on water permeability is counterbalanced by several factors such as prostaglandin E2, bradykinin, dopamin, endotelin-1 and others. Changes in AQP-2 expression / trafficking are of particular importance in pathological conditions characterized by both diluting and concentration defect of renal function.

[The role of protein kinase C in the establishment of the mechanism of vasopressin antidiuretic action in the rat kidney during mammalian postnatal development]

The kidney of immaturely born mammals in early postnatal development is insensitive to the effect of the antidiuretic hormone, vasopressin. It has been demonstrated that water permeability of the epithelial cells in the collecting ducts of a rat kidney increases during development; in this process, the response to desmopressin, an agonist of vasopressin V2 receptors, appears at the age of 20 days. The observed increase in water permeability is connected with an increased content of the water channel's proteins aquaporins AQP2 and AQP3 in the plasma membrane. The calcium-dependent protein kinase C isoforms are the likely components of the vasopressin signal's transduction and are possibly involved in the mechanisms underlying the maturation of sensitivity to this hormone. The contents of three protein kinase C isoforms (alpha, delta, and zeta) in rats at different periods of their postnatal development were estimated using Western blot hybridization. It has been shown that the contents of protein kinase C isoforms alpha and delta increase with development, whereas the content of isoform zeta remains constant. The most likely participant of the mechanism providing for maturation of the cell's hormonal competence for vasopressin is the calcium-dependent protein kinase Ca, because it's content in the plasma membrane is maximal on days 20-24, which coincides with the time when the vasopressin action appears.

Involvement of interstitial structures of the kidney into hydrosmotic effect of vasopressin (morphofunctional study)

Administration of desmopressin for 4 days to homozygous Brattleboro rats lacking endogenous vasopressin induced an increase in osmotic concentration and was accompanied by typical changes in the morphofunctional state of interstitial cells of the renal papilla. These changes increase the permeability of extracellular matrix, which attested to the involvement of interstitial cells into hydrosmotic reaction to vasopressin.

[Fast nongenomic aldosterone effect on the kinetics of intracellular sodium and cell volume in the cortical part of collecting ducts of the rat kidney]

The fast nongenomic aldosterone effect on intracellular sodium ([Na+]i) and cell volume was studied by the fluorescent microscopy in isolated cortical part of collecting duct of the rat kidney (CCD). It was shown that aldosterone (10 nM) raised [Na+]i in hyposodium outer medium (14 mM). The rate of [Na+]i changes in response to external sodium shift (137-14 mM) twice as low in the presence of aldosterone (p < 0.05). Corticosterone (100 nM) was unable to simulate aldosterone effect. Similarly to sodium channel blocker amiloride (10(-5) M), protein kinase C (PKC) inhibitor RO-31-8220 (10(-7) M) abolished aldosterone effect. Aldosterone (10 nM) significantly decreased the amplitude and increased the characteristic time of the cell volume restoration in hypotonic medium of the rat principle cells (p < 0.001). Corticosterone (50 nM) was also unable to reproduce aldosterone effect. Amiloride (10(-5) M) did not significantly influence either the amplitude or the characteristic time of cell volume restoration during hypoosmotic challenge (p > 0.05). For the first time the specificity and important role of Ca(2+)-dependent kinase in the nongenomic aldosterone effects on ENaC activity and cell volume regulation in rat CCD were demonstrated.

[The effect of vasopressin and its analogs on hyaluronan-synthase type 2 gene expression in Wistar and vasopressin-deficient Brattleboro rat kidney]

Effect of vasopressin and its analogs on the expression of HAS2 gene in different functional zones of Wistar and homozygous vasopressin-defficient Brattlboro rat kidneys was analyzed using RT-PCR method. It has been found that in the inner medulla of Wistar rat kidney the content of HAS2 mRNA depends on the level ofvasopressin in the blood: treatment by dDAVP (agonist of V2 receptor) suppressed the expression of HAS2, whereas lowered vasopressin secretion under hydration caused increase of HAS2 mRNA content. In the inner medulla of vasopressin-deficient Brattleboro rat kidney, exogenous arginin-vasopressin and its analog AVP-A (agonist of V2 and antagonist of V1a receptor) suppressed HAS2 expressin. It seems that U2 receptor takes part in hormonal regulation HA metabolism system. The age-related dynamics of HAS2 expression in the medulla were studied in 5, 10 and 30-days old rats of both strains. HAS2 gene expressed during the early period of postnatal life in the medulla and reached maximum on the 30th day. The comparison of the data obtained in Wistar and Brattleboro rats suggest that vasopressin suppresses HAS2 expression in the inner medulla of adult rat kidney and has no influence on the maturing of the HA synthesis enzyme system during postnatal development.

[Results of treatment in patients with destructive pulmonary tuberculosis without consideration of drug sensitivity in Mycobacterium tuberculosis]

Treatment of 63 patients having infiltrative and disseminated pulmonary tuberculosis attended by decay and bacterial excretion with 4 essential drugs (isoniazid, rifadine, pyrazinamide, ethambutol) and, in disseminated processes, additionally with streptomycin without determining their drug sensitivity contributed to the cessation of sputum acid-resistant mycobacteria in 96.8% and to cavity cicatrisation in 77.8%. Irregular use of izoniazid and rifadine during continued treatment is one of the reasons for the low rates of cavity resolution.

Structural and functional changes in epitheliocytes of collecting tubes in renal papilla of Brattleboro rats treated with vasopressin

The functional response of the kidney to desmopressin and morphological changes in epitheliocytes of collecting tubes were studied on homozygotic Brattleboro rats. Redistribution of beta-glucuronidase fractions and increase in the number of osmiophilic granules reflecting increased production of vasopressin-dependent proteins and hyaluronate hydrolase exocytosis were typical structural correlates of the effect of vasopressin.

[Effect of dDAVP, agonist of V2 vasopressin receptor on the hyaluronidase-1 and hyaluronidase-2 gene expression in the kidneys of Wistar and Brattleboro rats]

Effect of vasopressin on the expression of Hyal-1 and Hyal-2 genes in different functional zones of Wistar and homozygous vasopressin-defficient Brattlboro rat kidneys was analysed using RT-PCR mehod. It was found that, in Wistar rats the content of Hyal-1 mRNA was higher in the medulla than in other kidney zones at the normal water and food regimen. The level of Hyal-1 mRNA in the cortex and the medulla of Brattlboro rat kidney exceeded that of papilla. There were no significant differences in the Hyal-2 mRNA content detected between functional zones of Wistar and Brattlboro rat kidneys. The treatment by dDAVP, the agonist of V2 vasopressin receptor (Desmopressin, 10 microg/100 g b.w.i.p. twice a day for two days) induced an increase in urine osmolality and significant increase in the Hyal-1 and Hyal-2 mRNA content in the medulla without changes in the cortex and papilla. The effect was more pronounced in Brattlboro rat kidney. These results demonstrate that, in control conditions, genes encoding Hyal-1 and Hyal-2 were expressed independently in all functional kidney zones in the both in normal Wistar and in vasopressin-defficient Brattlboro rats. Desmopressin (dDAVP) exerts a stimulating effect on Hyal-1 and Hyal-2 gene expression in the medulla.

[Developmental pecularuties of aldosterone regulation of rat epithelial Na channel expression and functional activity]

Developmental changes of mRNA alfa-subunit ENaC abundance in renal cortex of 10-day old and in adult rats and aldosterone (10 nM) influence on it were studied. The mRNA level was lower in young rat renal cortex and there was no aldosterone effect on it within 5 hours and 30 minutes, in contrast to adult rats. Intracellular sodium concentration [Na+ i] measured by fluorescent dye Na+ Green in CCD fragments micro-dissected from the kidneys was lower in fragments from immature kidneys, whereas fast nongenomic of aldosterone (10 nM) was the same at both ages. Aldosterone significantly raised [Na+ i] by 40 and 50% in conditions of low sodium concentration (14 mM) in outer medium in epithelial cells of both type of CCD fragments from 10-day old and adult animals, respectively (p < 0.05). We assume that heterochrony of fast and long time genomic effect takes place in aldosterone molecular mechanism maturation. Fast nongenomic effect on the [Na+ i] appeared earlier compared to delayed genomic effect of aldosterone mediated through the changes of the mRNA alpha-subunit ENaC abundance.

[G(i) proteins in regulation of water permeability of the rat kidney collecting tube epithelium cell membrane]

Principal mechanism of the transepithelial water permeability increase in the kidney collecting ducts in response to vasopressin involves insertion of aquaporin 2 (AQP2) into the apical membrane. Previously we have shown that water permeability of the basolateral membrane also may be increased with stimulation of V2-receptors. It is known that inhibition of G(i)-proteins with pertussis toxin blocks redistribution of AQP2 into the apical membrane following the application of vasopressin or forskolin. The aim of the present study was to investigate potential involvement of G(i)-proteins in regulation of basolateral membrane water permeability. Effect of pertussis toxin on the ability of desmopressin to increase the basolateral membrane osmotic water permeability was investigated, and the expression of Galpha(i)2 and Galpha(i)3 genes under normal conditions and after 2 days of water deprivation were evaluated. We demonstrated that dehydration leds to a 30% increase of Galpha(i)3 mRNA content while the Galpha(i)2 mRNA level remains unchanged. In control experiments, basolateral membrane water permeability increased in response to desmopressin from 59.2 +/- 6.61 to 70.6 +/- 9.2 microm/s (p < 0.05, paired t-test). Pertussis toxin completely blocked this reaction (53.5 +/- 5.18 vs 50.1 +/- 6.50 microm/s, respectively). We conclude that G(i)-proteins participate in the mechanism of the basolateral membrane water permeability increase in response to stimulation of V2-receptors. Clarification of the G(i)-proteins role in this process requires further investigation, but most likely they are involved in regulation of aquaporin transport and insertion into the cell membrane.