Synthesis and characterization of UV curable biocompatible hydrophilic copolymers containing siloxane units.

Tissues are highly three-dimensional structure complexes composed of different cell types and their interactions. One of the main challenges in tissue engineering is the inability to produce large, highly perfused scaffolds in which cells can grow at a high cell density and viability. Poly(dimethyl siloxane) (PDMS) is used as a flexible, biocompatible cell culture substrate with tunable mechanical properties. However, its fragility and hydrophobicity still pose a challenge. Here, we present a new strategy for the three-step one-pot synthesis of novel biocompatible hydrophilic copolymers containing siloxane units. In the first step, free radical copolymerization of acrylic acid (AA), butyl methacrylate (BMA), and 2-hydroxyethyl methacrylate (HEMA) was carried out in dioxane (DO) solution in the presence of 2,2'-azodiisobutyronitrile (AIBN). In the second step, the copolymers were modified with diepoxypropoxypropyl-terminated polydimethylsiloxane (DE-PDMS), and in the third step, the copolymers were additionally modified with glycidyl methacrylate (GMA). The modified copolymers were characterized by FTIR, NMR spectroscopy and elemental analysis. Films of modified copolymers were prepared by UV curing. SEM studies revealed microphase separated morphology with distribution of PDMS domains. The mechanical properties of the films depended on the amount of incorporated silicone modifier. The films were more hydrophilic than PDMS films. All novel copolymers showed high biocompatibility.

FBN1 polymorphisms in patients with the dilatative pathology of the ascending thoracic aorta.

OBJECTIVES: To investigate polymorphisms of the fibrillin-1 (FBN1) gene (namely, rs2118181, rs1036477, rs10519177, rs755251 and rs4774517) in a case-control study for dilatative pathology of the ascending thoracic aorta (DPATA) from Lithuanians. METHODS: We studied 312 patients who had undergone aortic reconstructive surgery for DPATA. These patients were sub-divided according to the phenotypes of their DPATA into (i) ascending aortic aneurysm (n = 160), (ii) post-stenotic dilatation of the ascending aorta due to aortic valve stenosis (n = 79) and (iii) Stanford A dissection (n = 73). The reference group (n = 472) was recruited from a random sample screened within epidemiological studies of the Lithuanian population. FBN1 polymorphisms were studied by real-time polymerase-chain-reaction amplification. RESULTS: Patients within the aortic dissection sub-group had significantly higher minor allele frequencies in all five FBN1 single nucleotide polymorphism (SNPs) studied versus reference group subjects (P < 0.0001). Minor allele frequencies in SNPs rs2118181, rs1036477 were significantly higher in those with aortic aneurysm when compared with the reference group (P = 0.007). Thus, minor alleles of FBN1 SNPs studied were significantly associated with aortic dissection with odds ratios (ORs) 2.59-2.13, P < 0.001, while SNPs rs2118181 and rs1036477 with an increased risk of ascending aortic aneurysm [OR 1.67, confidence interval (CI) 95% 1.61-2.40]. The association of FBN1 genotypes with each phenotype of DPATA was assessed using logistic regression models adjusted for gender, age and hypertension. The additive model best fitted SNPs rs2118181 and rs1036477 in association with the ascending aortic aneurysm sub-group (OR 1.70, CI 95% 1.17-2.46) or the Stanford A dissection sub-group (OR 2.64, CI 95% 1.66-4.19). A recessive model fitted best the association between SNPs rs10519177, rs755251, rs4774517 and Stanford A dissection (OR 4.31, CI 95% 2.06-9.01). There were no significant associations between all studied FBN1 SNPs and post-stenotic or bicuspid aortic dilatation. CONCLUSIONS: Our study provides evidence for the following: (i) FBN1 SNPs rs2118181, rs1036477, rs10519177, rs4774517, rs755251 may increase susceptibility to aortic dissections and (ii) FBN1 SNPs rs2118181, rs1036477 to the formation of aortic aneurysms. Thus, these SNPs might be considered as biomarkers for identifying patients at risk for ascending aortic aneurysm and aortic dissection.

Surgical correction of atrial septal defect in the elderly.

INTRODUCTION: Atrial septal defects (ASDs) are one of the most common congenital malformations in adults. Correction of ASDs in advanced age remains controversial, even though beneficial effects in this patient group were found in recent studies. In older patients, less invasive transcatheter closure of ASDs has been recommended. AIM: The aim of this study was to analyze our advanced age ASD surgical cohort: early and late results. MATERIAL AND METHODS: Retrospective analysis of 32 patients operated on at an age of ≥ 60 years (i.e. age 66.13 ± 4.8, range from 60 to 78) in our center between 2001 and 2011 was carried out. We reviewed our experience of surgical ASD closure in elderly patients over a 10-year period to assess the effects of this type of treatment on early postoperative and long-term survival, early and late complications, preoperative and postoperative clinical status (New York Heart Association [NYHA] functional class), pulmonary hypertension (PH) and atrial arrhythmias. The patients were divided into two groups according to age. RESULTS: The frequency of comorbidities was lower in younger age group patients (11 [61%] vs. 13 [93%], p < 0.05). Atrial fibrillation/flutter was found in 21 (66%) of all patients. Late postoperative mortality was higher in the older patient group (3 [21%] vs. 1 [5.6%]). Despite this, we observed significant improvement of symptoms and functional ability in the older population after surgical ASD closure (group I, n = 10 [56%] vs. group II, n = 12 [86%]). CONCLUSIONS: Surgical correction of clinically significant ASD is effective even in older patients with comorbidities.

Micro-structured polymer scaffolds fabricated by direct laser writing for tissue engineering.

This work presents the latest results on direct laser writing of polymeric materials for tissue engineering applications. A femtosecond Yb:KGW laser (300 fs, 200 kHz, 515 nm) was used as a light source for non-linear lithography. Fabrication was implemented in various photosensitive polymeric materials, such as: hybrid organic-inorganic sol-gel based on silicon-zirconium oxides, commercial ORMOCER® class photoresins. These materials were structured via multi-photon polymerization technique with submicron resolution. Porous three-dimensional scaffolds for artificial tissue engineering were fabricated with constructed system and were up to several millimeters in overall size with 10 to 100 µm internal pores. Biocompatibility of the used materials was tested in primary rabbit muscle-derived stem cell culture in vitro and using laboratory rats in vivo. This interdisciplinary study suggests that proposed technique and materials are suitable for tissue engineering applications.

Recovery of infarcted myocardium in an in vivo experiment.

UNLABELLED: Acute myocardial infarction leads to the loss of functional cardiomyocytes and structural integrity. The adult heart cannot repair the damaged tissue due to inability of mature cardiomyocytes to divide and lack of stem cells. The aim of this study was to evaluate the efficiency of introduced autologous skeletal musclederived stem cells to recover the function of acutely infarcted rabbit heart in the early postoperative period. MATERIAL AND METHODS: As a model for myocardium restoration in vivo, experimental rabbit heart infarct was used. Autologic adult myogenic stem cells were isolated from skeletal muscle and propagated in culture. Before transplantation, the cells were labeled with 4',6-diamidino-2-phenylindole and then, during heart surgery, introduced into the rabbit acutely infarcted myocardium. Postoperative cardiac function was monitored by recording electrocardiograms and echocardiograms. At the end of the experiment, the efficiency of cell integration was evaluated histologically. RESULTS: Rabbit cardiac function recovered after 1 month after the induction of experimental infarction both in the control and experimental groups. Therefore, the first month after the infarction was the most significant for the assessment of cell transplantation efficacy. Transplanted cell integration into infarcted myocardium was time- and individual-dependent. Evaluation of changes in left ventricular ejection fraction after the induction of myocardial infarction revealed better recovery in the experimental group; however, the difference among animals in the experimental and control groups varied and was not significant. CONCLUSIONS. Autologous myogenic stem cells repopulated infarcted myocardium with different efficiency in each individual. This variability may account for the observed difference in postoperative cardiac recovery in a rabbit model.

[Closure of atrial septal defect via small lateral thoracotomies, partial and full length sternotomies]. / Priesirdziu pertvaros defekto pasalinimas per nedideles sonines torakotomijas, daline bei pilnutine sternotomijas.

Surgical closure of atrial septal defect is considered a low risk procedure. Various minimally invasive surgical techniques spread over the conventional full-length sternotomy. But the risk profile and complication rates of the minimally invasive closure of atrial septal defect are not revealed sufficiently. We present the results of atrial septal defect surgery via small thoracotomies: right anterolateral, right posterolateral, partial sternotomies and full-length median sternotomies. Ninety four patients underwent surgical closure of atrial septal defect via minimal approaches through the period from February 1999 to December 2001. Via median sternotomies were operated 85 patients. Right anterolateral group consisted of 17 patients, right posterolateral - 68, partial sternotomies - 9. The intracardiac period of operation was performed on electrical fibrillation under mild hypothermia. Median bypass time was 33 min. in right anterolateral, 31 min. - right posterolateral, 32 min. - partial sternotomies, 37 min. - median sternotomies. Median fibrillation time was 21 min. in right anterolateral, 18 min. - right posterolateral, 15 min. - partial sternotomies, 21 min. - median sternotomies. There were no technical procedure related complications in minimally invasive group. Intrahospital morbidity consisted of 6 pneumonias, 4 pleural effusions. There were 3 pneumonias, 2 pleural and 2 pericardial effusions in median sternotomies group.