Association between serum homocysteine and in-hospital death in patients with acute pulmonary embolism / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the association between serum homocysteine (Hcy) level and in-hospital death in patients with acute pulmonary embolism.</p><p><b>METHODS</b>A total of 186 acute pulmonary embolism patients [ (66.8 ± 12.7) years, 89 male] hospitalized in our department between June 2008 and June 2011 were included in this prospective study. Patients were divided into high Hcy group (Hcy ≥ 15.2 µmol/L, n = 95) and low Hcy group (Hcy < 15.2 µmol/L, n = 91). Patients were followed-up for 1 year for the incidence rate of early death associated with acute pulmonary embolism. The Cox proportional hazard model was used to analyze the relationship between serum Hcy level and early death in acute pulmonary embolism patients.</p><p><b>RESULTS</b>Patients were hospitalized for 1-37 days [(10 ± 6) days]. In-hospital death rate was 14.5% (27/186) and was significantly higher in high Hcy group than in low Hcy group [25.3% (24/95) vs. 3.3% (3/91) , P = 0.001]. Univariate Cox regression analysis indicated that admission heart rate, oxygen saturation, enlargement of right ventricle, Hcy ≥ 15.2 µmol/L, serum creatinine level, peak TnT level and deep venous thrombosis (P < 0.05) were independent risk factors for in-hospital death. Multivariate Cox regression analysis showed that Hcy ≥ 15.2 µmol/L (HR = 4.10, 95%CI:3.00-4.98, P = 0.017), admission heart rate (HR = 1.10, 95%CI:1.01-1.20, P = 0.031) , deep venous thrombosis (HR = 1.65, 95%CI:1.45-1.76, P = 0.034) and age (HR = 1.10, 95%CI:1.02-1.19, P = 0.010) were independent predictors of in-hospital death for acute pulmonary embolism patients. One-year follow up was finished in 142 patients (89.3%). There were 19 deaths ( 5 due to repeat pulmonary embolism, 4 due to decompensated respiratory and /or cardiac diseases, 6 due to malignant tumors, 2 due to fatal bleeding and 2 due to pneumonia) . Death rate was similar between the two groups during follow up.</p><p><b>CONCLUSION</b>Higher serum homocysteine is an independent for in-hospital death for patients with acute pulmonary embolism.</p>

Direct AFM observation of saposin C-induced membrane domains in lipid bilayers: from simple to complex lipid mixtures.

Saposin C (Sap C) is a small glycoprotein required by glucosylceramidase (GCase) for hydrolysis of glucosylceramide to ceramide and glucose in lysosomes. The molecular mechanism underlying Sap C stimulation of the enzyme activation is not fully understood. Here, atomic force microscopy (AFM) has been used to study Sap C-membrane interactions under physiological conditions. First, to establish how Sap C-membrane interactions affect membrane structure, lipid bilayers containing zwitterionic and anionic phospholipids were used. It was observed that Sap C induced two types of membrane restructuring effects, i.e., the formation of patch-like domains and membrane destabilization. Bilayers underwent extensive structural reorganization. To validate the biological importance of the membrane restructuring effects, interaction of Sap C with lipid bilayers composed of cholesterol, sphingomyelin, and zwitterionic and anionic phospholipids were studied. Although similar membrane restructuring effects were observed, Sap C-membrane interactions, in this case, were remarkably modulated and their effects were restricted to a limited area. As a result, nanometer-sized domains were formed. The establishment of a model membrane system will allow us to further study the dynamics, structure and mechanism of the Sap C-associated membrane domains and to examine the important role that these domains may play in enzyme activation.

Phospholipid membrane interactions of saposin C: in situ atomic force microscopic study.

Saposin C (Sap C) is a small glycoprotein required for hydrolysis of glucosylceramidase in lysosomes. The full activity of glucosylceramidase requires the presence of both Sap C and acidic phospholipids. Interaction between Sap C and acidic phospholipid-containing membranes, a crucial step for enzyme activation, is not fully understood. In this study, the dynamic process of Sap C interaction with acidic phospholipid-containing membranes was investigated in aqueous buffer using atomic force microscopy. Sap C induced two types of membrane restructuring: formation of patch-like structural domains and the occurrence of membrane destabilization. The former caused thickness increase whereas the latter caused thickness reduction in the gel-phase membrane bilayer, possibly as a result of lipid loss or an interdigitating process. Patch-like domain formation was independent of acidic phospholipids, whereas membrane destabilization is dependent on the presence and concentration of acidic phospholipids. Sap C effects on membrane restructuring were further studied using synthetic peptides. Synthetic peptides corresponding to the amphipathic alpha-helical domains 1 (designated "H1 peptide") and 2 (H2 peptide) of Sap C were used. Our results indicated that H2 contributed to domain formation but not to membrane destabilization, whereas H1 induced neither type of membrane restructuring. However, H1 was able to mimic Sap C's destabilization effect in conjunction with H2, but only when H1 was present first and H2 was added afterwards. This study provides an approach to investigate the structure-function aspects of Sap C interaction with phospholipid membranes, with insights into the mechanism(s) of Sap C-membrane interaction.

Lattice-like array particles on Xenopus oocyte plasma membrane.

Plasma membrane from Xenopus laevis oocytes has been used as a model system to study membrane structure and particle components, including native and exogenously expressed proteins. Previous studies by electron microscopy (EM) and atomic force microscopy (AFM) compared intramembrane particles (IMPs) on uninjected oocyte membranes to oocytes expressing proteins of interest. These studies observed randomly distributed IMPs on the surface of the oocyte plasma membrane. In this paper, we introduce a novel technique to isolate oocyte membranes by bursting the oocyte and depositing its membrane on a flat mica substrate. The flat surface membrane preparation allows high-resolution AFM images to beobtained, revealing a novel structure of densely packed particles. These particles exhibit a regular, repeating pattern of a lattice-like array with orderly packing and are thus termed "lattice-like array particles" (LAPs). The LAPs are orderly yet imperfectly packed, are located in depressed pools, occur with a low frequency on the oocyte membrane surface, and have not previously been seen using other isolation and imaging methods. Histogram analysis of the center-to-center distance between LAPs suggest their size to be about 44 nm in diameter, considerably larger than other reported size estimates of IMPs. These results indicate that LAPs represent a novel membrane particle organization, which merits further study.