Endothelial Dysfunction and Brachial Intima-Media Thickness: Long Term Cardiovascular Risk with Claudication Related to Peripheral Arterial Disease: A Prospective Analysis

Objective

Endothelial dysfunction plays a key role in the development, progression, and clinical manifestation of atherosclerosis, and in symptomatic peripheral arterial disease, endothelial dysfunction and enlarged intima-media thickness might be associated with increased cardiovascular risk. Flow-mediated dilatation and serologic parameters are used to evaluate individual endothelial function. Brachial intima-media thickness, a less recognized parameter of cardiovascular risk, is independently associated with coronary artery disease. The aim of this study was to evaluate the prognostic value of ultrasound and serologic parameters of endothelial function in relation to cardiovascular mortality in peripheral arterial disease.

Design

monocentric, prospective cohort study.

Methods

Flow mediated dilatation and brachial intima-media thickness were assessed in 184 (124 male) patients with peripheral arterial disease (Rutherford stages 2–3). Serologic parameters of endothelial function included asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and L-homoarginine. Cardiovascular events were recorded during a follow-up of 99.1±11.1 months. Subjects who died of noncardiovascular causes were excluded from further analysis.

Results

Eighty-two patients (44.6%) died during follow-up after a mean duration of 49.7±28.3 months. There were 49 cardiovascular deaths (59.8%) and 33 other deaths (40.2%). Flow mediated dilatation was associated with cardiovascular death [1.17% (0.0, 4.3) vs. 4.1% (1.2, 6.4), p<0.001]. Intima-media thickness was greater in patients who succumbed to cardiovascular disease [0.37 mm (0.30, 0.41)] than in survivors [0.21 mm (0.15, 0.38), p<0.001]. Brachial intima-media thickness above 0.345 mm was most predictive of cardiovascular death, with sensitivity and specificity values of 0.714 and 0.657, respectively (p<0.001). Furthermore, ADMA levels above 0.745 µmol/l and SDMA levels above 0.825 µmol/l were significantly associated with cardiovascular death (p<0.001 and 0.030).

Conclusion

In symptomatic peripheral arterial disease, decreased flow mediated dilatation, enlarged intima-media thickness, and elevated levels of ADMA and SDMA were associated with increased cardiovascular risk.     

Non-covalent interactions result in aggregation of surface antigens of the parasitic nematode Trichinella spiralis.

Surface antigens of three stages of the nematode worm Trichinella spiralis has been labelled with iodine and examined by sodium dodecyl sulphate (SDS)/polyacrylamide-gel electrophoresis under reducing and non-reducing conditions. A variety of interactions were defined: the infective larva surface antigens formed a spectrum of aggregates from 50kDa to greater than 1000kDa from subunits of 47kDa and 90kDa; in the adult worms of 60kDa complex arose fron interaction between two dissimilar molecules of 40kDa and 20kDa; the new-born larvae components formed homologous dimers from a 58kDa molecule. Aggregating molecules were adherent to lentil lectin-Sepharose and are therefore glycoproteins. The interactions observed were completely abolished by boiling in SDS/mercaptoethanol, but only partially destroyed by boiling in SDS/iodoacetamide. Based upon this, the associations can be characterized as non-covalent, but disulphide-bond-dependent. It is suggested, but not proved, that the aggregates arise from strong non-covalent hydrophobic interaction sites which are stabilized by intrachain disulphide bonds in the molecules concerned.     

Biotic and abiotic factors affecting survival of early life history intervals of a stream-dwelling sunfish

Synopsis Biotic interactions, such as competition and predation, and abiotic events, such as floods, both have important consequences for organisms inhabiting warmwater streams. Empirical studies can lead to better understanding of how these factors interact to affect distinct life history intervals of stream fishes. Survival of eggs, embryos and larvae in nests of longear sunfishLepomis megalotis was monitored in a section of Jordan Creek for four years. During two years characterized by low, relatively stable flow, nest failures could be attributed to biotic interactions. During two years with more variable flow, most brood losses occurred during floods. Flooding led to nest desertion and loss of offspring regardless of nest location. The number of nests constructed tended to be lower during years with more variable flow. The proportion of nests with successful broods did not differ between colonial and solitary nests. Variation in flow regime modifies the importance of biotic effects on survival of early life history intervals of longear sunfish.     

p21 Inhibits Cdk1 in the absence of Cdk2 to maintain the G1/S phase DNA damage checkpoint

Cdk1 was proposed to compensate for the loss of Cdk2. Here we present evidence that this is possible due to premature translocation of Cdk1 from the cytoplasm to the nucleus in the absence of Cdk2. We also investigated the consequence of loss of Cdk2 on the maintenance of the G1/S DNA damage checkpoint. Cdk2(-/-) mouse embryonic fibroblasts in vitro as well as regenerating liver cells after partial hepatectomy (PH) in Cdk2(-/-) mice, arrest promptly at the G1/S checkpoint in response to gamma-irradiation due to activation of p53 and p21 inhibiting Cdk1. Furthermore re-entry into S phase after irradiation was delayed in Cdk2(-/-) cells due to prolonged and impaired DNA repair activity. In addition, Cdk2(-/-) mice were more sensitive to lethal irradiation compared to wild-type and displayed delayed resumption of DNA replication in regenerating liver cells. Our results suggest that the G1/S DNA damage checkpoint is intact in the absence of Cdk2, but Cdk2 is important for proper repair of the damaged DNA.     

Computational analysis of small RNA cloning data

Cloning and sequencing is the method of choice for small regulatory RNA identification. Using deep sequencing technologies one can now obtain up to a billion nucleotides--and tens of millions of small RNAs--from a single library. Careful computational analyses of such libraries enabled the discovery of miRNAs, rasiRNAs, piRNAs, and 21U RNAs. Given the large number of sequences that can be obtained from each individual sample, deep sequencing may soon become an alternative to oligonucleotide microarray technology for mRNA expression profiling. In this report we present the methods that we developed for the annotation and expression profiling of small RNAs obtained through large-scale sequencing. These include a fast algorithm for finding nearly perfect matches of small RNAs in sequence databases, a web-accessible software system for the annotation of small RNA libraries, and a Bayesian method for comparing small RNA expression across samples.     

Neutropenia with impaired immune response to Streptococcus pneumoniae in ceramide kinase-deficient mice

In mammals, ceramide kinase (CerK)-mediated phosphorylation of ceramide is the only known pathway to ceramide-1-phosphate (C1P), a recently identified signaling sphingolipid metabolite. To help delineate the roles of CerK and C1P, we knocked out the gene of CerK in BALB/c mice by homologous recombination. All in vitro as well as cell-based assays indicated that CerK activity is completely abolished in Cerk-/- mice. Labeling with radioactive orthophosphate showed a profound reduction in the levels of de novo C1P formed in Cerk-/- macrophages. Consistently, mass spectrometry analysis revealed a major contribution of CerK to the formation of C16-C1P. However, the significant residual C1P levels in Cerk-/- animals indicate that alternative routes to C1P exist. Furthermore, serum levels of proapoptotic ceramide in these animals were significantly increased while levels of dihydroceramide as the biosynthetic precursor were reduced. Previous literature pointed to a role of CerK or C1P in innate immune cell function. Using a variety of mechanistic and disease models, as well as primary cells, we found that macrophage- and mast cell-dependent readouts are barely affected in the absence of CerK. However, the number of neutrophils was strikingly reduced in blood and spleen of Cerk-/- animals. When tested in a model of fulminant pneumonia, Cerk-/- animals developed a more severe disease, lending support to a defect in neutrophil homeostasis following CerK ablation. These results identify ceramide kinase as a key regulator of C1P, dihydroceramide and ceramide levels, with important implications for neutrophil homeostasis and innate immunity regulation.