Reactivity of isocyanates with urethanes: Conditions for allophanate formation

International audienceThe reactions between two polyisocyanates, 4,4#-methylenebis(phenyl isocyanate) (MDI) and trimer of isophorone diisocyanate (tIPDI) and a model arylealkyl diurethane were carried out at high temperature (>=170 °C) and several NCO/urethane ratios.A combination of 1H and 13C NMR and MALDI-TOF spectroscopies was used and allows the identification of reaction products.When MDI or tIPDI is reacted with a diurethane at high temperature and after cooled, allophanates are formed but notisocyanurates. 13C NMR was used to quantify the different reaction products obtained under different experimental conditions.Only a few allophanates (%10%) are obtained after 1 h of reaction

The interaction between wetland nutrient content and plant quality controls aquatic plant decomposition

International audienceWe conducted an in situ decomposition experiment to better understand how habitat nutrient content controls aquatic plant decomposition and, more precisely, to determine the relative importance of the wetland conditions in decomposition, and the intrinsic degradability of plant tissues. We collected the green leaves of three aquatic plant species with contrasting plant strategies from three wetlands of differing nutrient contents, and allowed them todecompose in seven wetlands along a nutrient gradient. The plant mass loss was higher for competitive and ruderal species collected in nutrient richer wetlands as well as when they were led to decompose in nutrient richer wetlands. Plant water content correlated with mass loss for the competitive and ruderal species, which may explain the increase in mass loss with increasing nutrient content in the collection wetlands. Litter decomposition rate may be enhanced by wetland eutrophication, because of both the modification of wetland decomposition conditions and by changes in plant tissue quality

Production and crystallization of the C-propeptide trimer from human procollagen III

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Effects of the self-myocardial retroperfusion with aortic-coronary sinus shunt on cardiac output and ischemic events in high-risk patients undergoing OPCAB surgery

Aim. Despite controversies, off-pump coronary artery bypass (OPCAB) surgery has become a routine procedure. Obvious advantages have been demonstrated in high-risk patients. However, OPCAB surgery has limitations in specific high-risk situations with hazards of operative deleterious events. We describe an innovative procedure of self-myocardial retroperfusion (SMR) with an aortic-coronary sinus shunt (ACSS). We prospectively evaluated the protective effects and benefits of SMR in high-risk coronary patients with impaired LVEF. Methods. Eighteen consecutive high-risk (ES>10) coronary patients (mean age: 65.94 years; range: 34-85; mean ES: 26.97%) with LVEF≤35% who were not eligible for IABP were assigned for OPCAB surgery. Following sternotomy, the cardiac indexes (CI) were measured before, during SMR and after completion of coronary artery bypasses. Operative events with and without SMR were accurately collected, and postoperative cardiac Troponin T release was measured. Results. OPCAB procedures were performed in all patients. Intraoperative use of SMR significantly increased CI (P=3.1041810.10-8) and reversed deleterious operative events (ECG changes/low cardiac output). Hospital mortality was 0%. Incidence of transient atrial ibrillation was 33.33%. Neither stroke nor renal insufficiency was observed. The mean graft number/ patient was 2.05. Mean postoperative cardiac Troponin T value was 0.79 μg/L. Beating heart preservation optimized by SMR contributed to reduce ischemiareperfusion injury, as validated by an immediate increase of CI after completion of coronary bypasses (P=3.35009.10-9). Conclusion. The concept of SMR with an ACSS during OPCAB procedures definitely improved CI and reversed ischemic features in high-risk patients and should be considered as an operative temporary myocardial assistance

Off-pump axillo-coronary artery bypass: A simple approach for high-risk myocardial revascularization

We report the case of a 66-year-old male with increasing angina occurring after two previous coronary artery surgery procedures. The second operation had been complicated by severe mediastinitis necessitating surgical drainage, and sternal stabilization. Angiography revealed an occlusion of the LAD bypass with a patent LAD associated with a stenotic circumflex coronary artery. The ascending aorta was severely calcified. An off-pump axillo-LAD coronary artery bypass was safely performed in conjunction with stenting of the circumflex artery. This approach dramatically simplified the procedure and reduced the operative risk. At the 52-month follow-up, the patient is free of any angina symptoms. doi: 10.1111/jocs.12113 (J Card Surg 2013;28:388-390) © 2013 Wiley Periodicals, Inc

Structural basis of homo- and heterotrimerization of collagen I

Fibrillar collagen molecules are synthesized as precursors, procollagens, with large propeptide extensions. While a homotrimeric form (three α1 chains) has been reported in embryonic tissues as well as in diseases (cancer, fibrosis, genetic disorders), collagen type I usually occurs as a heterotrimer (two α1 chains and one α2 chain). Inside the cell, the role of the C-terminal propeptides is to gather together the correct combination of three α chains during molecular assembly, but how this occurs for different forms of the same collagen type is so far unknown. Here, by structural and mutagenic analysis, we identify key amino acid residues in the α1 and α2 C-propeptides that determine homo- and heterotrimerization. A naturally occurring mutation in one of these alters the homo/heterotrimer balance. These results show how the C-propeptide of the α2 chain has specifically evolved to permit the appearance of heterotrimeric collagen I, the major extracellular building block among the metazoa

Planering och prioritering av inköp i tidiga skeden : En studie om kommande projekt på en central inköpsenhet i ett svenskt byggbolag

Fibrillar collagen molecules are synthesized as precursors, procollagens, with large propeptide extensions. While a homotrimeric form (three α1 chains) has been reported in embryonic tissues as well as in diseases (cancer, fibrosis, genetic disorders), collagen type I usually occurs as a heterotrimer (two α1 chains and one α2 chain). Inside the cell, the role of the C-terminal propeptides is to gather together the correct combination of three α chains during molecular assembly, but how this occurs for different forms of the same collagen type is so far unknown. Here, by structural and mutagenic analysis, we identify key amino acid residues in the α1 and α2 C-propeptides that determine homo- and heterotrimerization. A naturally occurring mutation in one of these alters the homo/heterotrimer balance. These results show how the C-propeptide of the α2 chain has specifically evolved to permit the appearance of heterotrimeric collagen I, the major extracellular building block among the metazoa