On-Surface Synthesis of Organolanthanide Sandwich Complexes.

The synthesis of lanthanide-based organometallic sandwich compounds is very appealing regarding their potential for single-molecule magnetism. Here, it is exploited by on-surface synthesis to design unprecedented lanthanide-directed organometallic sandwich complexes on Au(111). The reported compounds consist of Dy or Er atoms sandwiched between partially deprotonated hexahydroxybenzene molecules, thus introducing a distinct family of homoleptic organometallic sandwiches based on six-membered ring ligands. Their structural, electronic, and magnetic properties are investigated by scanning tunneling microscopy and spectroscopy, X-ray absorption spectroscopy, X-ray linear and circular magnetic dichroism, and X-ray photoelectron spectroscopy, complemented by density functional theory-based calculations. Both lanthanide complexes self-assemble in close-packed islands featuring a hexagonal lattice. It is unveiled that, despite exhibiting analogous self-assembly, the erbium-based species is magnetically isotropic, whereas the dysprosium-based compound features an in-plane magnetization.

Lanthanide metal-organic network featuring strong perpendicular magnetic anisotropy.

The coordination of lanthanides atoms in two-dimensional surface-confined metal-organic networks is a promising path to achieve an ordered array of single atom magnets. These networks are highly versatile with plenty of combinations of molecular linkers and metallic atoms. Notably, with an appropriate choice of molecules and lanthanide atoms it should be feasible to tailor the orientation and intensity of the magnetic anisotropy. However, up to now only tilted and almost in-plane easy axis of magnetizations were reported in lanthanide-based architectures. Here we introduce an Er-directed two-dimensional metallosupramolecular network on Cu(111) featuring strong out-of-plane magnetic anisotropy. Our results will contribute to pave avenues for the use of lanthanides in potential applications in nanomagnetism and spintronics.

Remarkably stable metal-organic frameworks on an inert substrate: M-TCNQ on graphene (M = Ni, Fe, Mn).

Potential applications of 2D metal-organic frameworks (MOF) require the frameworks to be monophase and well-defined at the atomic scale, to be decoupled from the supporting substrate, and to remain stable at the application conditions. Here, we present three systems meeting this elusive set of requirements: M-TCNQ (M = Ni, Fe, Mn) on epitaxial graphene/Ir(111). We study the systems experimentally by scanning tunneling microscopy, low energy electron microscopy and X-ray photoelectron spectroscopy. When synthesized on graphene, the 2D M-TCNQ MOFs are monophase with M1(TCNQ)1 stoichiometry, no alternative structure was observed with slight variation of the preparation protocol. We further demonstrate a remarkable chemical and thermal stability of TCNQ-based 2D MOFs: all the studied systems survive exposure to ambient conditions, with Ni-TCNQ doing so without any significant changes to its atomic-scale structure or chemical state. Thermally, the most stable system is Fe-TCNQ which remains stable above 500 °C, while all the tested MOFs survive heating to 250 °C. Overall, the modular M-TCNQ/graphene system combines the atomic-scale definition required for fundamental studies with the robustness and stability needed for applications, thus we consider it an ideal model for research in single atom catalysis, spintronics or high-density storage media.

The predictive potential of asymptomatic mild elevation of cardiac troponin I on mortality risk of stable patients with vascular disease.

OBJECTIVES: Due to improved analytical performance of the newest generation of troponin assays, several patients have mild elevations of this parameter. Nevertheless, they do not show any signs of acute coronary syndrome. We speculated whether non-acute cardiac troponin I (cTnI) concentrations may improve prediction of residual mortality risk in clinically stable outpatients with chronic vascular disease. DESIGN AND METHODS: We followed 830 patients (mean age 65.2years) after myocardial infarction, coronary revascularization or first ischemic stroke (pooled Czech samples of EUROASPIRE III and EUROASPIRE-stroke surveys, interviewed in 2006/2007) in a prospective cohort study. In addition to standard protocol, troponin I and brain natriuretic peptide (BNP) was estimated from frozen samples. Vital status and declared cause of death from death certificates was registered to ascertain a 5-year all-cause and cardiovascular mortality. RESULTS: During a median follow up of 2050days (5.6years) 168 patients died. In the multivariate Cox proportional hazard model, cTnI≥0.03ng/mL independently predicted an all-cause 5-year mortality with HRR 1.76 (95% CI: 1.09-2.83). In the Cox model, the better predictor of mortality was BNP >150ng/L [HRR 3.47 (95% CI: 2.23-5.41)]. However, the combination of BNP with cTnI did not substantially improve its sensitivity or predictive power. CONCLUSION: We cannot confirm the utility of asymptomatic mild cTnI elevation as a tool to detect residual risk of stable patients with vascular disease. On the other hand, BNP seems to be more appropriate for this purpose.

Length of occlusion predicts recanalization and outcome after intravenous thrombolysis in middle cerebral artery stroke.

BACKGROUND AND PURPOSE: The length of large vessel occlusion is considered a major factor for therapy in patients with ischemic stroke. We used 4D-CT angiography evaluation of middle cerebral artery occlusion in prediction of recanalization and favorable clinical outcome and after intravenous thrombolysis (IV-tPA). METHODS: In 80 patients treated with IV-tPA for acute complete middle cerebral artery/M1 occlusion determined using CT angiography and temporal maximum intensity projection, calculated from 4D-CT angiography, the length of middle cerebral artery proximal stump, occlusion in M1 or M1 and M2 segment were measured. Univariate and multivariate analyses were performed to define independent predictors of successful recanalization after 24 hours and favorable outcome after 3 months. RESULTS: The length of occlusion was measureable in all patients using temporal maximum intensity projection. Recanalization thrombolysis in myocardial infarction 2 to 3 was achieved in 37 individuals (46%). The extension to M2 segment as a category (odds ratio, 4.58; 95% confidence interval, 1.39-15.05; P=0.012) and the length of M1 segment occlusion (odds ratio, 0.82; 95% confidence interval, 0.73-0.92; P=0.0007) with an optimal cutoff value of 12 mm (sensitivity 0.67; specificity 0.71) were significant independent predictors of recanalization. Favorable outcome (modified Rankin scale 0-2) was achieved in 25 patients (31%), baseline National Institutes of Health Stroke Scale (odds ratio, 0.82; 95% confidence interval, 0.72-0.93; P=0.003) and the length of occlusion M1 in segment (odds ratio, 0.79; 95% confidence interval, 0.69-0.91; P=0.0008) with an optimal cutoff value of 11 mm (sensitivity 0.74; specificity 0.76) were significant independent predictors of favorable outcome. CONCLUSIONS: The length of middle cerebral artery occlusion is an independent predictor of successful IV-tPA treatment.

Unexpected inverse relationship between impaired glucose metabolism and lipoprotein-associated phospholipase A2 activity in patients with stable vascular disease.

BACKGROUND: Elevated lipoprotein-associated phospholipase A2 activity (aLp-PLA2) is associated with increased risk of cardiovascular events. In patients with stable atherovascular disease, we aimed to investigate whether impaired glucose metabolism might be associated with higher risk of elevated aLp-PLA2. METHODS: We conducted a cross-sectional study in 825 stable patients after acute coronary syndrome, coronary revascularization or after first ischemic stroke (Czech part of EUROASPIRE III surveys). We measured aLp-PLA2 using diaDexus commercial kit. RESULTS: In multiple step-wise regression analysis, the aLp-PLA2 was significantly positively associated with male gender, current smoking, LDL cholesterol and metabolic syndrome and negatively with statin treatment, body mass index and LDL/apoB ratio. After adjustment for these confounders, we observed an inverse relationship between aLp-PLA2 and fasting glycemia [ß coefficient -2.18 (p<0.0001)] or glycated hemoglobin A1c (HbA1c) [ß coefficient -5.89 (p<0.0001)]. Moreover, we found a positive association between aLp-PLA2 and pancreatic ß cell function [ß coefficient +0.10 (p<0.0001)], but not with an insulin sensitivity. CONCLUSION: In present study, we cannot confirm any additive risk of impaired glucose metabolism in terms of increased activity of Lp-PLA2. On the contrary, presence of inadequately controlled diabetes mellitus was independently associated with lower risk of elevated aLp-PLA2 .

Desphospho-uncarboxylated matrix Gla-protein is associated with mortality risk in patients with chronic stable vascular disease.

BACKGROUND: Vitamin K is the essential co-factor for activation of matrix Gla-protein (MGP), the natural inhibitor of tissue calcification. Biologically inactive, desphospho-uncarboxylated MGP (dp-ucMGP) is a marker of vascular vitamin K status and is described to predict mortality in patients with heart failure and aortic stenosis. We hypothesized that increased dp-ucMGP might be associated with mortality risk in clinically stable patients with chronic vascular disease. MATERIALS AND METHODS: We examined 799 patients (mean age 65.1 ± 9.3 years) who suffered from myocardial infarction, coronary revascularization or first ischemic stroke (pooled Czech samples of EUROASPIRE III and EUROASPIRE-stroke surveys), and followed them in a prospective cohort study. To estimate the 5-year all-cause and cardiovascular mortality we ascertained vital status and declared cause of death. Circulating dp-ucMGP and desphospho-carboxylated MGP (dp-cMGP) were measured by ELISA methods (IDS and VitaK). RESULTS: During a median follow-up of 2050 days (5.6 years) 159 patients died. In the fully adjusted multivariate Cox proportional hazard model, the patients in the highest quartile of dp-ucMGP (≥ 977 pmol/L) had higher risk of all-cause and cardiovascular 5-year mortality [HRR 1.89 (95% CI, 1.32-2.72) and 1.88 (95% CI, 1.22-2.90)], respectively. Corresponding HRR for dp-cMGP were 1.76 (95% CI, 1.18-2.61) and 1.79 (95% CI, 1.12-2.57). CONCLUSIONS: In patients with overt vascular disease, circulating dp-ucMGP and dp-cMGP were independently associated with the risk of all-cause and cardiovascular mortality. Since published results are conflicting regarding the dp-cMGP, we propose only circulating dp-ucMGP as a potential biomarker for assessment of additive cardiovascular risk.

Some immunological properties of female saliva and its effect on sperm motility.

BACKGROUND: In this study, we investigated pH, levels of IgA, IgG, IgM, lysozyme and spermagglutinating antibodies in human saliva of healthy women, with or without hormonal contraception (HC) and their effect on sperm motility. METHODS AND RESULTS: Saliva was collected immediately after waking up from 59 healthy randomly selected women. We measured pH in sera and in saliva as well as immunoglobulin G, A and M levels in saliva by radial immunodiffusion. Sperm - saliva capillary penetration test in native saliva served for examination of sperm motility, indirect-MAR test for detection of sperm antibodies in sera, and in saliva, both observed by inverted microscope. The average pH values in native saliva according to the menstrual cycles were: from 2-5 days 6.896, from 6-17 days 7.027, and from 18 and more days 7.17. Rapid decrease of sperm motility was registered in acidic saliva in comparison with alkaline. The average concentration of IgA, IgG, IgM and lysozyme slightly differed in women with or without hormonal contraception. Moderate decreasing of sperm motility was found in saliva with higher levels of IgA. No sperm agglutinating antibodies in saliva and in serum were detected in all subjects. CONCLUSIONS: The pH of saliva is influenced by several causes (hormonal, immunological, microbiological factors, by meal and drinks, smoking, etc.). We demonstrated that sperm motility is lower in acidic saliva. pH is markedly changed during various days of menstrual cycles. We proved individual high levels of saliva IgA. Human saliva used as coital lubricant decreases sperm motility, but does not replace a local form of contraception.