An AFM study of solid-phase bilayers of unsaturated PC lipids and the lateral distribution of the transmembrane model peptide WALP23 in these bilayers

An altered lipid packing can have a large influence on the properties of the membrane and the lateral distribution of proteins and/or peptides that are associated with the bilayer. Here, it is shown by contact-mode atomic force microscopy that the surface topography of solid-phase bilayers of PC lipids with an unsaturated cis bond in their acyl chains shows surfaces with a large number of line-type packing defects, in contrast to the much smoother surfaces observed for saturated PC lipids. Di-n:1-PC (n = 20, 22, 24) and (16:0,18:1)-PC (POPC) were used. Next, the influence of an altered lipid environment on the lateral distribution of the single α-helical model peptide WALP23 was studied by incorporating the peptide in the bilayers of di-n:1-PC (n = 20, 22, 24) and (16:0,18:1)-PC unsaturated lipids. The presence of WALP23 leads to an increase in the number of packing defects but does not lead to the formation of the striated domains that were previously observed in bilayers of saturated PC lipids and WALP. This is ascribed to the less efficient lateral lipid packing of the unsaturated lipids, while the increase in packing defects is probably an indirect effect of the peptide. Finally, the fact that an altered lipid packing affects the distribution of WALP23 is also confirmed in an additional experiment where the solvent TFE (2,2,2-trifluorethanol) is added to bilayers of di-16:0-PC/WALP23. At 3.5 vol% TFE, the previous striated ordering of the peptide is abolished and replaced by loose lines

Cervical artery dissection goes frequently undiagnosed.

Cervical artery dissection (CeAD) is a frequent cause of stroke among young patients. It is unclear how many CeADs occur asymptomatically or cause subtle and unspecific clinical symptoms. We hypothesize that CeAD remains often unrecognized. Accordingly, the incidence of CeAD might be higher and the stroke risk lower than generally assumed. Lack of CeAD-indicating clinical symptoms is regarded as the main cause of missed diagnoses. We further hypothesize that underrepresentation of asymptomatic and oligosymptomatic patients in CeAD studies may have biased the association between ischemia and local symptoms in CeAD patients as well as the associations of CeAD with risk factors or co-morbidities. We finally hypothesize that symptomatic CeAD may be preceded by an initial asymptomatic phase. According to this final hypothesis, the time of onset of CeAD should be considered uncertain. The issue of unrecognized CeAD is relevant, as it may affect the associations between CeAD and putative risk factors. Furthermore, the existence of clinically silent CeADs may explain why recurrent and familial CeAD have been rarely observed

Hyperglycaemia in critical illness is a risk factor for later development of type II diabetes mellitus

Hyperglycaemia caused by stress and inflammation is common during critical illness. We hypothesised that a latent glucose metabolism disturbance contributes to development of hyperglycaemia and that those patients have increased risk for diabetes. We included patients with sepsis, acute coronary syndrome and acute heart failure with no history of impaired glucose metabolism and divided them in the hyperglycaemia group (glucose ≥ 7.8 mmol/l) and normoglycaemia group. Patients were followed for 5 years. Follow-up was completed for 115 patients in the normoglycaemia group, of which 4 (3.5%) developed type 2 diabetes. In the hyperglycaemia group 51 patients finished follow-up and 8 (15.7%) developed type 2 diabetes. Relative risk in 5-year period for patients with hyperglycaemia was 4.51 for development of type 2 diabetes. Patients with hyperglycaemia during critical illness who are not diagnosed with diabetes before or during the hospitalisation should be considered a population at increased risk for developing diabetes

Gender and cervical artery dissection.

Background and purpose: To analyze previously established gender differences in cervical artery dissection (CeAD). Methods: This case-control study is based on the CADISP (Cervical Artery Dissection and Ischemic Stroke Patients) population comprising 983 consecutive CeAD patients (mean age: 44.1±9.9years) and 658 control patients with a non-CeAD ischemic stroke (IS) (44.5±10.5years). Results: Cervical artery dissection was more common in men (56.7% vs. 43.3%, P<0.001) and men were older (46.4 vs. 41.0years, P<0.001). We assessed putative risk factors for CeAD including vascular risk factors, recent cervical trauma, pregnancies, and infections. All gender differences in the putative risk factors and outcome were similar in the CeAD and the non-CeAD IS groups. Conclusion: Our analysis of the largest collection of CeAD patients to date confirms male predominance and differences in age at dissection between men and women. Gender differences in putative risk factors may explain the higher frequency of CeAD in men and their older age, but the putative risk factors are probably not specific for CeAD. © 2011 The Author(s). European Journal of Neurology © 2011 EFNS.SCOPUS: ar.jFLWINinfo:eu-repo/semantics/publishe