Structure and Chemical Composition of Soil C-Rich Al-Si-Fe Coprecipitates at Nanometer Scale

Soil carbon stabilization is mainly driven by organo-mineral interactions. Coprecipitates, of organic matter with short-range order minerals, detected through indirect chemical extraction methods, are increasingly recognized as key carbon sequestration phases. Yet the atomic structure of these coprecipitates is still rather conceptual. We used transmission electron microscopy imaging combined with energy-dispersive X-ray and electron energy loss spectroscopy chemical mappings, which enabled direct nanoscale characterization of coprecipitates from Andosols. A comparison with reference synthetic coprecipitates showed that the natural coprecipitates were structured by an amorphous Al, Si, and Fe inorganic skeleton associated with C and were therefore even less organized than short-range order minerals usually described. These amorphous types of coprecipitates resembled previously conceptualized nanosized coprecipitates of inorganic oligomers with organics (nanoCLICs) with heterogeneous elemental proportions (of C, Al, Si, and Fe) at nanoscale. These results mark a new step in the high-resolution imaging of organo-mineral associations, while shedding further light on the mechanisms that control carbon stabilization in soil and more broadly in aquatic colloid, sediment, and extraterrestrial samples.

Controlling differentiation of stem cells via bioactive disordered cues

Ideal bone tissue engineering is to induce bone regeneration through the synergistic integration of biomaterial scaffolds, bone progenitor cells, and bone-forming factors. Biomimetic scaffolds imitate the native extracellular matrix (ECM) and are often utilized in vitro as analogues of the natural ECM to facilitate investigations of cell-ECM interactions and processes. In vivo, the cellular microenvironment has a crucial impact on regulating cell behavior and functions. A PET surface was activated and then functionalized with mimetic peptides to promote human mesenchymal stem cell (hMSC) adhesion and differentiation into an osteogenic lineage. Spray technology was used to randomly micropattern peptides (RGD and BMP-2 mimetic peptides) on the PET surface. The distribution of the peptides grafted on the surface, the roughness of the surfaces and the chemistry of the surfaces in each step of the treatment were ascertained by atomic force microscopy, fluorescence microscopy, time-of-flight secondary ion mass spectrometry, Toluidine Blue O assay, and X-ray photoelectron spectroscopy. Subsequently, cell lineage differentiation was evaluated by quantifying the expression of immunofluorescence markers: osteoblast markers (Runx-2, OPN) and osteocyte markers (E11, DMP1, and SOST). In this article, we hypothesized that a unique combination of bioactive micro/nanopatterns on a polymer surface improves the rate of morphology change and enhances hMSC differentiation. In DMEM, after 14 days, disordered micropatterned surfaces with RGD and BMP-2 led to a higher osteoblast marker expression than surfaces with a homogeneous dual peptide conjugation. Finally, hMSCs cultured in osteogenic differentiation medium (ODM) showed accelerated cell differentiation. In ODM, our results highlighted the expression of osteocyte markers when hMSCs were seeded on PET surfaces with random micropatterns.

Does It Matter the Fixation Method of The Posterior Malleolar Fragment in Trimalleolar Fractures?

PURPOSE OF THE STUDY The purpose of this study was to evaluate if the fixation method of a posterior fragment in trimalleolar ankle fractures affects the surgical outcomes. MATERIAL AND METHODS A retrospective evaluation was made of all the cases of trimalleolar fractures over a 9-year period in a trauma center. Patients aged 18 - 70 years were enrolled in the study. Patients were separated into 2 groups according to the fixation method (A - P percutaneous screw, and posterior open reduction - internal fixation). The fractures were classified according to the AO classification system and the Haraguchi posterior malleolar fracture classification system. The FAOS and SF-36 scores, postoperative reduction quality, arthritis scores and minor - major complications were evaluated. RESULTS 86 patients were found to eligible for the study. The PMF was fixed using anteroposterior percutaneous screw in 50 (58.1 %) patients and with posterior open reduction-internal fixation in 36 (41.9 %) patients. AO 44 B type fracture was determined in 89.5 % of the patients, AO 44 C type was seen in 10.5 %. There were 27 patients (31.4 %) with Haraguchi type 1 fracture and 59 patients (68.6 %) with type 2 fracture. The mean step-off of the articular surface was statistically greater in Group 1 than in Group 2. No statistically significant difference was determined between the two groups in respect of syndesmosis malreduction. The mean arthritis score was higher in Group 1 than in Group 2. Mean scores of the SF-36 and FAOS questionnaire was statistically significantly improved in the patients with open reduction and internal fixation. DISCUSSION Although there is no consensus on the treatment of posterior malleolar fractures, the indication for surgery is mainly based on posterior fragment size in the literature. The anatomic articular reduction has been emphasized recently. In this study, it was determined that the anatomic articular reduction was correlated with better surgical outcomes. CONCLUSIONS The study results demonstrated that better functional and radiological outcomes was observed with direct open reduction and fixation of the posterior fragment than indirect reduction and percutaneous fixation in the patients with trimalleolar fracture. The arthritis risk and patient satisfaction were seen to be correlated with the anatomic reduction of the articular surface. Key words: trimalleolar fracture, posterior malleolar fracture, percutaneous screw, open reduction and fixation, ankle fracture.

559 An analysis of myocardial efficiency in patients with severe asymptomatic mitral regurgitation

Funding Acknowledgements

None declared.

Background and Aims

It is difficult to determine left ventricular systolic performance in patients with severe mitral regurgitation (MR) since left ventricular ejection fraction (EF) could be preserved until the end stages of the disease. Myocardial efficiency describes the amount of external work (EW) done by the left ventricle per unit of oxygen consumed (mVO2). In the present study, we aimed to investigate MEf in patients with asymptomatic severe MR using a novel echocardiographic method. Methods: A total of 27 patients with severe asymptomatic MR and 26 healthy volunteers were included in this cross-sectional study. EW was measured using stroke volume and blood pressure, while mVO2 was estimated using double product and LV mass. Results: There were no differences between the groups with regards to EF (66%±5% vs. 69%±7%), while MEf was significantly reduced in patients with severe MR (25%±11% vs. 44%±12%, p < 0.001) (Table 1). This difference was maintained even after adjustment for age, gender and body surface area (adjusted :0.44, 95%CI: 0.39–0.49 for controls and adjusted :0.24, 95%CI: 0.19–0.29 for patients with severe MR). Further analysis showed that this reduction was due to an increase in total mVO2 in the severe MR group (Figure 1). Conclusions: Myocardial efficiency was significantly lower in patients with asymptomatic severe MR and preserved EF.

Table 1 Parameter Control Group (n = 26) Severe Mitral Regurgitation (n = 27) P Value Age (y) 36.5 ± 8.9 41.3 ± 14.2 0.23 Gender (%Male) 9 (35%) 10 (37%) 1.0 BSA (m2) 1.82 ± 0.20 1.76 ± 0.18 0.64 LV End-Diastolic Volume (ml) 83.13 ± 18.88 121.91 ± 37.63 <0.001 LV End-Systolic Volume (ml) 28.07 ± 9.57 45.30 ± 17.42 <0.001 Left Ventricular Ejection Fraction (%) 0.69 ± 0.07 0.66 ± 0.05 0.29 Systolic Mitral Velocity (cm/s) 7.88 ± 1.14 8.07 ± 1.81 0.66 Stroke Work (j) 1.14 ± 0.21 1.15 ± 0.36 0.91 Minute External Work (j) 65.96 ± 14.71 70.17 ± 23.15 0.85 mVO2 (ml.min-1.100g-1) 6.79 ± 1.93 9.48 ± 4.71 0.02 Total mVO2 (j) 166.58 ± 77.14 346.46 ± 202.71 <0.001 Myocardial Efficiency (%) 44 ± 12 25 ± 11 <0.001 Table 1. Demographic, anthropometric, echocardiographic and mechanoenergetic data for study groups. BSA, body surface area; LV, left ventricle; mVO2, myocardial oxygen consumption.

Abstract 559 Figure 1

Cyanobacterial formation of intracellular Ca-carbonates in undersaturated solutions

Cyanobacteria have long been thought to induce the formation of Ca-carbonates as secondary by-products of their metabolic activity, by shifting the chemical composition of their extracellular environment to conditions favoring mineral precipitation. Some cyanobacterial species forming Ca-carbonates intracellularly were recently discovered. However, the environmental conditions under which this intracellular biomineralization process can occur and the impact of cyanobacterial species forming Ca-carbonates intracellularly on extracellular carbonatogenesis are not known. Here, we show that these cyanobacteria can form Ca-carbonates intracellularly while growing in extracellular solutions undersaturated with respect to all Ca-carbonate phases, that is, conditions thermodynamically unfavorable to mineral precipitation. This shows that intracellular Ca-carbonate biomineralization is an active process; that is, it costs energy provided by the cells. The cost of energy may be due to the active accumulation of Ca intracellularly. Moreover, unlike cyanobacterial strains that have been usually considered before by studies on Ca-carbonate biomineralization, cyanobacteria forming intracellular carbonates may slow down or hamper extracellular carbonatogenesis, by decreasing the saturation index of their extracellular solution following the buffering of the concentration of extracellular calcium to low levels.

Selective Uptake of Alkaline Earth Metals by Cyanobacteria Forming Intracellular Carbonates

The uptakes of calcium (Ca), strontium (Sr), and barium (Ba) by two cyanobacterial strains, Cyanothece sp. PCC7425 and Gloeomargarita lithophora, both forming intracellular carbonates, were investigated in laboratory cultures. In the culture medium BG-11 amended with 250 μM Ca and 50 or 250 μM Sr and Ba, G. lithophora accumulated first Ba, then Sr, and finally Ca. Sr and Ba were completely accumulated by G. lithophora cells at rates between 0.02 and 0.10 fmol h^-1 cell^-1 and down to extracellular concentrations below the detection limits of inductively coupled plasma atomic emission spectroscopy. Accumulation of Sr and Ba did not affect the growth rate of the strain. This sequential accumulation occurred mostly intracellularly within polyphosphate and carbonate granules and resulted in the formation of core-shell structures in carbonates. In contrast, Cyanothece sp. PCC7425 showed neither a preferential accumulation of heavier alkaline earth metals nor core-shell structures in the carbonates. This indicated that fractionation between alkaline earth metals was not inherent to intracellularly calcifying cyanobacteria but was likely a genetically based trait of G. lithophora. Overall, the capability of G. lithophora to sequester preferentially Sr and Ba at high rates may be of considerable interest for designing new remediation strategies and better understanding the geochemical cycles of these elements.

Effects of Levosimendan on Left Ventricular Functional Remodelling and Exercise Intolerance: A Tissue Doppler Study

Levosimendan is a calcium sensitizer that demonstrates enhanced myocardial contractility. There is little information concerning the effect of levosimendan on left ventricular tissue parameters and exercise capacity. We evaluated the effects of a 24-h course of levosimendan therapy on cardiac tissue parameters in 30 patients, aged 48-70 years, admitted to our hospital for the management of decompensated heart failure. All patients underwent echocardiographic examination using tissue Doppler imaging (TDI) and a 6-min walk test. Systolic myocardial velocity of the mitral annulus (Sm) was significantly increased in levosimendantreated patients compared with placebotreated patients. There was a positive correlation between Sm and exercise capacity. Levosimendan might be expected to increase cardiac contractile force, especially Sm velocity, in parallel with exercise tolerance. The study has also shown that the progress of ventricular function after levosimendan treatment in patients with exercise intolerance could be monitored effectively by Sm velocity measurements using TDI.

Echo-guided pericardiocentesis in patients with clinically significant pericardial effusion. Outcomes over a 10-year period

BACKGROUND

The purpose of the present study is to evaluate current echocardiographically (echo)-guided pericardiocentesis practice with regard to procedural success, complication rate, etiological causes, and outcomes of patients with clinically significant pericardial effusion.

PATIENTS AND METHODS

Patients who underwent echo-guided pericardiocentesis between January 2004 and February 2014 were identified using an institutional code for the procedure. Other complementary data were obtained by interviewing patients or their relatives (directly or by telephone) and by searching the social security death index.

RESULTS

A total of 301 patients were identified. The pericardium was approached via the subcostal (85 %) or apical (15 %) route under echo guidance in all procedures. The success rate was 97 %, with an intervention-requiring complication rate of 1.3 %. No patient died from complications. The most common etiology was malignancy (n = 84, 28 %). Patients were followed-up for a median of 35 months. Median survival for patients with malignant effusion was 5.9 months compared with 54 months for those with nonmalignant effusion.

CONCLUSIONS

Echo-guided pericardiocentesis has a high success and low complication rate in current practice. Among etiologies, malignancy remains the most common cause of clinically significant pericardial effusion and is associated with a poor prognosis.

Human erythrocytes covered with magnetic core-shell nanoparticles for multimodal imaging

Surface functionalization of human red blood cells (hRBCs) with fluorescent and magnetic silica core-shell nanoparticles is used to design a carrier suitable for multimodal imaging with a long circulating time. The coated magnetic hRBCs show no hemolytic activity, while the advantage of the affinity of proteins for silica allows a further coating.

Laser angioplasty in a right coronary artery stent restenosis with the guidance of left internal mammary artery contrast injection: case report

A 43-years-old male who underwent right coronary artery stent implantation 6 months ago presented with total occlusion of right coronary artery at proximal part of the stent without antegrade flow. We successfully used the left internal mammary artery contrast injections for guidance in all stages of the right coronary laser angioplasty intervention.