Biomedical subjects

Marko I Turina

Publications and source records attributed to Marko I Turina.

25 records · Page 2Linked to original sources

PubMed2003

The clinical anatomy of the sinus node artery.

BACKGROUND: Our basic aim was to describe the topographic relation between the sinus node artery and the superior posterior border of the interatrial septum with regard to the sinus node dysfunction that follows the superior transseptal approach to the mitral valve. METHODS: During our study 50 human hearts without previous pathologic alterations were analyzed. The position of the sinus node and the course of the sinus node artery were investigated. For identification of the origin of the artery, selective coronary angiograms were performed. The course of sinus node artery and its topographic relation to the interatrial septum was identified by the dry dissections of the hearts. Based on histologic and dry dissected specimens the exact position of the sinus node was determined. RESULTS: We found that the sinus node artery originates from the right coronary artery in 66% of examined cases and from the left coronary artery in 34% of cases. The sinus node artery crosses the superior posterior border of the interatrial septum in 54% of cases. CONCLUSIONS: Our results were compared with clinical studies focusing the incidence of the sinus rhythm disturbance after the superior transseptal approach. The incidence of rhythm disturbance varies from 52% to 60% of cases. Comparing our morphologic and clinical results we can state that the risk for intraoperative damage to the sinus node artery during the superior transseptal approach to the mitral valve is high.

Adult↗

PubMed2003

Hypoxia and reoxygenation do not upregulate adhesion molecules and natural killer cell adhesion on human endothelial cells in vitro.

OBJECTIVES: Ischemia/reperfusion injury is characterized by endothelial cell activation leading to increased expression of adhesion molecules such as inter-cellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, endothelial- and platelet-selectin (E- and P-selectin), and to the subsequent recruitment of leukocytes. The aim of the present study was to investigate the respective effects of a proinflammatory cytokine (tumor necrosis factor alpha, TNF-alpha), hypoxia and/or reoxygenation on adhesion molecule expression and natural killer (NK) cell adhesion in an in vitro model of I/R. METHODS: Human aortic endothelial cells (HAEC) were stimulated in vitro for 8h with TNF-alpha (1000 U/ml) and exposed to hypoxia (1% O(2)), reoxygenation (21% O(2)) or different combinations thereof. Cell surface expression of ICAM-1, VCAM-1 and E-/P-selectin on HAEC was analyzed by flow cytometry, and culture supernatants were tested for soluble adhesion molecules by ELISA. Rolling adhesion of NK cells on HAEC was determined using a rotating assay. RESULTS: Untreated HAEC constitutively expressed ICAM-1 on their surface but neither expressed E-/P-selectin, VCAM-1, nor shedded soluble adhesion molecules. Exposure of HAEC to hypoxia or hypoxia and reoxygenation did not upregulate cell surface expression or shedding of adhesion molecules. In contrast, TNF-alpha significantly upregulated cell surface expression of ICAM-1, VCAM-1, and E-/P-selectin and led to the shedding of ICAM-1 and E-selectin. Combined treatment of HAEC with TNF-alpha, hypoxia and reoxygenation reduced E-/P-selectin surface expression and enhanced E-selectin shedding, but did not further influence ICAM-1 and VCAM-1. Soluble VCAM-1 was not detected. NK cell adhesion on HAEC increased 4-fold after TNF-alpha stimulation, but was not affected by hypoxia or hypoxia and reoxygenation. CONCLUSIONS: Both the expression of endothelial adhesion molecules and rolling NK cell adhesion was upregulated by TNF-alpha but not by hypoxia alone or hypoxia followed by reoxygenation supporting the view that anti-inflammatory treatment may reduce ischemia/reperfusion injury.

Aorta↗

PubMed2003

Preconditioning by sevoflurane decreases biochemical markers for myocardial and renal dysfunction in coronary artery bypass graft surgery: a double-blinded, placebo-controlled, multicenter study.

BACKGROUND: Preconditioning by volatile anesthetics is a promising therapeutic strategy to render myocardial tissue resistant to perioperative ischemia. It was hypothesized that sevoflurane preconditioning would decrease postoperative release of brain natriuretic peptide, a biochemical marker for myocardial dysfunction. In addition, several variables associated with the protective effects of preconditioning were evaluated. METHODS: Seventy-two patients scheduled for coronary artery bypass graft surgery under cardioplegic arrest were randomly assigned to preconditioning during the first 10 min of complete cardiopulmonary bypass with either placebo (oxygen-air mixture only) or sevoflurane 4 vol% (2 minimum alveolar concentration). No other volatile anesthetics were administered at any time during the study. Treatment was strictly blinded to anesthesiologists, perfusionists, and surgeons. Biochemical markers of myocardial dysfunction and injury (brain natriuretic peptide, creatine kinase-MB activity, and cardiac troponin T), and renal dysfunction (cystatin C) were determined. Results of Holter electrocardiography were recorded perioperatively. Translocation of protein kinase C was assessed by immunohistochemical analysis of atrial samples. RESULTS: Sevoflurane preconditioning significantly decreased postoperative release of brain natriuretic peptide, a sensitive biochemical marker of myocardial contractile dysfunction. Pronounced protein kinase C delta and epsilon translocation was observed in sevoflurane-preconditioned myocardium. In addition, postoperative plasma cystatin C concentrations increased significantly less in sevoflurane-preconditioned patients. No differences between groups were found for perioperative ST-segment changes, arrhythmias, or creatine kinase-MB and cardiac troponin T release. CONCLUSIONS: Sevoflurane preconditioning preserves myocardial and renal function as assessed by biochemical markers in patients undergoing coronary artery bypass graft surgery under cardioplegic arrest. This study demonstrated for the first time translocation of protein kinase C isoforms delta and epsilon in human myocardium in response to sevoflurane.

Adult↗

PubMed2002

Tissue engineering of functional trileaflet heart valves from human marrow stromal cells.

BACKGROUND: We previously demonstrated the successful tissue engineering and implantation of functioning autologous heart valves based on vascular-derived cells. Human marrow stromal cells (MSC) exhibit the potential to differentiate into multiple cell-lineages and can be easily obtained clinically. The feasibility of creating tissue engineered heart valves (TEHV) from MSC as an alternative cell source, and the impact of a biomimetic in vitro environment on tissue differentiation was investigated. METHODS AND RESULTS: Human MSC were isolated, expanded in culture, and characterized by flow-cytometry and immunohistochemistry. Trileaflet heart valves fabricated from rapidly bioabsorbable polymers were seeded with MSC and grown in vitro in a pulsatile-flow-bioreactor. Morphological characterization included histology and electron microscopy (EM). Extracellular matrix (ECM)-formation was analyzed by immunohistochemistry, ECM protein content (collagen, glycosaminoglycan) and cell proliferation (DNA) were biochemically quantified. Biomechanical evaluation was performed using Instron(TM). In all valves synchronous opening and closing was observed in the bioreactor. Flow-cytometry of MSC pre-seeding was positive for ASMA, vimentin, negative for CD 31, LDL, CD 14. Histology of the TEHV-leaflets demonstrated viable tissue and ECM formation. EM demonstrated cell elements typical of viable, secretionally active myofibroblasts (actin/myosin filaments, collagen fibrils, elastin) and confluent, homogenous tissue surfaces. Collagen types I, III, ASMA, and vimentin were detected in the TEHV-leaflets. Mechanical properties of the TEHV-leaflets were comparable to native tissue. CONCLUSION: Generation of functional TEHV from human MSC was feasible utilizing a biomimetic in vitro environment. The neo-tissue showed morphological features and mechanical properties of human native-heart-valve tissue. The human MSC demonstrated characteristics of myofibroblast differentiation.

Absorbable Implants↗

PubMed2002

Living, autologous pulmonary artery conduits tissue engineered from human umbilical cord cells.

BACKGROUND: Tissue engineering represents a promising approach to in vitro creation of living, autologous replacements with the potential to grow, repair, and remodel. Particularly in a congenital operation, there is a substantial need for such implantation materials. We previously demonstrated fabrication of completely autologous, functional heart valves on the basis of peripheral vascular cells. Presently the feasibility of creating pulmonary artery conduits from human umbilical cord cells was investigated. METHODS: Human umbilical cord cells were harvested and expanded in culture. Pulmonary conduits fabricated from rapidly bioabsorbable polymers were seeded with human umbilical cord cells and grown in vitro in a pulse duplicator bioreactor. Morphologic characterization of the generated neo-tissues included histology, transmission, and scanning electron microscopy. Characterization of extracellular matrix was comprised of immunohistochemistry. Extracellular matrix protein content and cell proliferation were quantified by biochemical assays. Biomechanical testing was performed using stress-strain and burst-stress tests. RESULTS: Histology of the conduits revealed viable, layered tissue and extracellular matrix formation with glycosaminoglycans and collagens I and III. Cells stained positive for vimentin and alpha-smooth muscle actin. Scanning electron microscopy showed confluent, homogenous tissue surfaces. Transmission electron microscopy demonstrated elements typical of viable myofibroblasts, such as collagen, fibrils, and elastin. Extracellular matrix proteins were significantly lower compared with native tissue; the cell content was increased. The mechanical strength of the pulsed constructs was comparable with native tissue; the static controls were significantly weaker. CONCLUSIONS: In vitro fabrication of tissue-engineered human pulmonary conduits was feasible utilizing human umbilical cord cells and a biomimetic culture environment. Morphologic and mechanical features approximated human pulmonary artery. Human umbilical cord cells demonstrated excellent growth properties representing a new, readily available cell source for tissue engineering without necessitating the sacrifice of intact vascular donor structures.

Absorbable Implants↗

PubMed2002

A new source for cardiovascular tissue engineering: human bone marrow stromal cells.

OBJECTIVE: Vascular-derived cells represent an established cell source for tissue engineering of cardiovascular constructs. Previously, cell isolation was performed by harvesting of vascular structures prior to scaffold seeding. Marrow stromal cells (MSC) demonstrate the ability to differentiate into multiple mesenchymal cell lineages and would offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. We studied the feasibility of using MSC as an alternative cell source for cardiovascular tissue engineering. METHODS: Human MSC were isolated from bone marrow and expanded in culture. Subsequently MSC were seeded on bioabsorbable polymers and grown in vitro. Cultivated cells and seeded polymers were studied for cell characterization and tissue formation including extracellular matrix production. Applied methods comprised flow cytometry, histology, immunohistochemistry, transmission (TEM) and scanning electron microscopy (SEM), and biochemical assays. RESULTS: Isolated MSC demonstrated fibroblast-like morphology. Phenotype analysis revealed positive signals for alpha-smooth muscle actin and vimentin. Histology and SEM of seeded polymers showed layered tissue formation. TEM demonstrated formation of extracellular matrix with deposition of collagen fibrils. Matrix protein analysis showed production of collagen I and III. In comparison to vascular-derived cell constructs quantitative analysis demonstrated comparable amounts of extracellular matrix proteins in the tissue engineered constructs. CONCLUSIONS: Isolated MSC demonstrated myofibroblast-like characteristics. Tissue formation on bioabsorbable scaffolds was feasible with extracellular matrix production comparable to vascular-cell derived tissue engineered constructs. It appears that MSC represent a promising cell source for cardiovascular tissue engineering.

Actins↗

PubMed2002

Technical details with the use of cryopreserved arterial allografts for aortic infection: influence on early and midterm mortality.

PURPOSE: In situ repair with cryopreserved vascular allografts improves the results in the surgical treatment of aortic infection. This study evaluated the technical pitfalls with the use of allografts that influence early and midterm mortality. METHODS: Between 1990 and 1999, 49 patients, 21 (43%) with a mycotic aneurysm and 28 (57%) with a prosthetic graft infection of the thoracic and abdominal aorta including pelvic and groin vessels, underwent in situ repair with cryopreserved arterial allografts. Seventeen patients (35%) had aortobronchial, aortoesophageal, or aortoenteric fistulas. RESULTS: Allograft-related technical problems occurred in eight patients (16%) in this series, and they included: intraoperative rupture caused by allograft friability; allograftenteric fistula from ligated allograft side branches rupturing 8, 18, and 48 months after implantation; anastomotic failure caused by inappropriate mechanical stress; anastomotic stricture after partial replacement of infected prosthetic grafts; allograft failure caused by inappropriate wound drainage; and recurrence of infection after inappropriate duration of antifungal treatment. Seven of the eight technical problems (87%) occurred in the first 10 patients (80%) in this series. There was one technical failure in the remaining 39 patients (2.6%; P =.0002) because of various technical adaptations, such as critical selection of allografts, use of allograft strips supporting large anastomoses, sealing with antibiotic-impregnated fibrin glue, and change in technique of allograft side-branch ligature. The 30-day mortality rate was 6% for the whole series; however, it was 2.6% for last 39 patients, with no recurrence of infection or allograft-related late death. CONCLUSIONS: In situ repair with cryopreserved arterial allografts achieves excellent early and late results in the treatment of aortic infection. However, distinct allograft-related technical problems had to be overcome to improve the outcome of patients with major vascular infections.

Adult↗